Merge tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linuxgrafted

Pull io_uring fixes from Jens Axboe:

 - Fix a task_work add use-after-free with SQPOLL.

   The sqpoll thread could pop and complete the last request while
   io_req_normal_work_add() was still looking at them after the mpscq
   push.

   Use the same approach as DEFER_TASKRUN to protect from that, holding
   an RCU read lock across the add, and have exit wait for an RCU grace
   period for SQPOLL rings as well.

 - CQE32 ring fixes: correct the free entry check for 32b CQEs, zero the
   big_cqe for aux CQEs, and only post the dummy skip CQE on CQE_MIXED
   rings

 - Mark the source filter table as COW when cloning bpf filters, so
   registering another filter on the source doesn't modify the shared
   table in place

 - Initialize the task context before running the BPF loop

 - Requeue zcrx multishot receives stopped by a local resource

 - End a TX_TIMESTAMP multishot cmd when the CQ is full (lollipopkit)

* tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  io_uring: fix task_work add use-after-free with SQPOLL
  io_uring/cmd_net: end TX_TIMESTAMP multishot when the CQ is full
  io_uring/zcrx: requeue multishot receives stopped by a local resource
  io_uring: initialize task context before running the BPF loop
  io_uring: zero big_cqe for aux CQEs on CQE32 rings
  io_uring: fix free entry check for 32b CQEs on CQE32 rings
  io_uring: only post the dummy skip CQE on CQE_MIXED rings
  io_uring/bpf_filter: mark source as COW when cloning filters

37 files changed, 7321 insertions, 0 deletions

diff --git a/Documentation/admin-guide/device-mapper/cache-policies.rst b/Documentation/admin-guide/device-mapper/cache-policies.rst
new file mode 100644
index 000000000..13da4d831
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/cache-policies.rst
@@ -0,0 +1,131 @@
+=============================
+Guidance for writing policies
+=============================
+
+Try to keep transactionality out of it.  The core is careful to
+avoid asking about anything that is migrating.  This is a pain, but
+makes it easier to write the policies.
+
+Mappings are loaded into the policy at construction time.
+
+Every bio that is mapped by the target is referred to the policy.
+The policy can return a simple HIT or MISS or issue a migration.
+
+Currently there's no way for the policy to issue background work,
+e.g. to start writing back dirty blocks that are going to be evicted
+soon.
+
+Because we map bios, rather than requests it's easy for the policy
+to get fooled by many small bios.  For this reason the core target
+issues periodic ticks to the policy.  It's suggested that the policy
+doesn't update states (eg, hit counts) for a block more than once
+for each tick.  The core ticks by watching bios complete, and so
+trying to see when the io scheduler has let the ios run.
+
+
+Overview of supplied cache replacement policies
+===============================================
+
+multiqueue (mq)
+---------------
+
+This policy is now an alias for smq (see below).
+
+The following tunables are accepted, but have no effect::
+
+	'sequential_threshold <#nr_sequential_ios>'
+	'random_threshold <#nr_random_ios>'
+	'read_promote_adjustment <value>'
+	'write_promote_adjustment <value>'
+	'discard_promote_adjustment <value>'
+
+Stochastic multiqueue (smq)
+---------------------------
+
+This policy is the default.
+
+The stochastic multi-queue (smq) policy addresses some of the problems
+with the multiqueue (mq) policy.
+
+The smq policy (vs mq) offers the promise of less memory utilization,
+improved performance and increased adaptability in the face of changing
+workloads.  smq also does not have any cumbersome tuning knobs.
+
+Users may switch from "mq" to "smq" simply by appropriately reloading a
+DM table that is using the cache target.  Doing so will cause all of the
+mq policy's hints to be dropped.  Also, performance of the cache may
+degrade slightly until smq recalculates the origin device's hotspots
+that should be cached.
+
+Memory usage
+^^^^^^^^^^^^
+
+The mq policy used a lot of memory; 88 bytes per cache block on a 64
+bit machine.
+
+smq uses 28bit indexes to implement its data structures rather than
+pointers.  It avoids storing an explicit hit count for each block.  It
+has a 'hotspot' queue, rather than a pre-cache, which uses a quarter of
+the entries (each hotspot block covers a larger area than a single
+cache block).
+
+All this means smq uses ~25bytes per cache block.  Still a lot of
+memory, but a substantial improvement nonetheless.
+
+Level balancing
+^^^^^^^^^^^^^^^
+
+mq placed entries in different levels of the multiqueue structures
+based on their hit count (~ln(hit count)).  This meant the bottom
+levels generally had the most entries, and the top ones had very
+few.  Having unbalanced levels like this reduced the efficacy of the
+multiqueue.
+
+smq does not maintain a hit count, instead it swaps hit entries with
+the least recently used entry from the level above.  The overall
+ordering being a side effect of this stochastic process.  With this
+scheme we can decide how many entries occupy each multiqueue level,
+resulting in better promotion/demotion decisions.
+
+Adaptability:
+The mq policy maintained a hit count for each cache block.  For a
+different block to get promoted to the cache its hit count has to
+exceed the lowest currently in the cache.  This meant it could take a
+long time for the cache to adapt between varying IO patterns.
+
+smq doesn't maintain hit counts, so a lot of this problem just goes
+away.  In addition it tracks performance of the hotspot queue, which
+is used to decide which blocks to promote.  If the hotspot queue is
+performing badly then it starts moving entries more quickly between
+levels.  This lets it adapt to new IO patterns very quickly.
+
+Performance
+^^^^^^^^^^^
+
+Testing smq shows substantially better performance than mq.
+
+cleaner
+-------
+
+The cleaner writes back all dirty blocks in a cache to decommission it.
+
+Examples
+========
+
+The syntax for a table is::
+
+	cache <metadata dev> <cache dev> <origin dev> <block size>
+	<#feature_args> [<feature arg>]*
+	<policy> <#policy_args> [<policy arg>]*
+
+The syntax to send a message using the dmsetup command is::
+
+	dmsetup message <mapped device> 0 sequential_threshold 1024
+	dmsetup message <mapped device> 0 random_threshold 8
+
+Using dmsetup::
+
+	dmsetup create blah --table "0 268435456 cache /dev/sdb /dev/sdc \
+	    /dev/sdd 512 0 mq 4 sequential_threshold 1024 random_threshold 8"
+	creates a 128GB large mapped device named 'blah' with the
+	sequential threshold set to 1024 and the random_threshold set to 8.
diff --git a/Documentation/admin-guide/device-mapper/cache.rst b/Documentation/admin-guide/device-mapper/cache.rst
new file mode 100644
index 000000000..f15e5254d
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/cache.rst
@@ -0,0 +1,337 @@
+=====
+Cache
+=====
+
+Introduction
+============
+
+dm-cache is a device mapper target written by Joe Thornber, Heinz
+Mauelshagen, and Mike Snitzer.
+
+It aims to improve performance of a block device (eg, a spindle) by
+dynamically migrating some of its data to a faster, smaller device
+(eg, an SSD).
+
+This device-mapper solution allows us to insert this caching at
+different levels of the dm stack, for instance above the data device for
+a thin-provisioning pool.  Caching solutions that are integrated more
+closely with the virtual memory system should give better performance.
+
+The target reuses the metadata library used in the thin-provisioning
+library.
+
+The decision as to what data to migrate and when is left to a plug-in
+policy module.  Several of these have been written as we experiment,
+and we hope other people will contribute others for specific io
+scenarios (eg. a vm image server).
+
+Glossary
+========
+
+  Migration
+	       Movement of the primary copy of a logical block from one
+	       device to the other.
+  Promotion
+	       Migration from slow device to fast device.
+  Demotion
+	       Migration from fast device to slow device.
+
+The origin device always contains a copy of the logical block, which
+may be out of date or kept in sync with the copy on the cache device
+(depending on policy).
+
+Design
+======
+
+Sub-devices
+-----------
+
+The target is constructed by passing three devices to it (along with
+other parameters detailed later):
+
+1. An origin device - the big, slow one.
+
+2. A cache device - the small, fast one.
+
+3. A small metadata device - records which blocks are in the cache,
+   which are dirty, and extra hints for use by the policy object.
+   This information could be put on the cache device, but having it
+   separate allows the volume manager to configure it differently,
+   e.g. as a mirror for extra robustness.  This metadata device may only
+   be used by a single cache device.
+
+Fixed block size
+----------------
+
+The origin is divided up into blocks of a fixed size.  This block size
+is configurable when you first create the cache.  Typically we've been
+using block sizes of 256KB - 1024KB.  The block size must be between 64
+sectors (32KB) and 2097152 sectors (1GB) and a multiple of 64 sectors (32KB).
+
+Having a fixed block size simplifies the target a lot.  But it is
+something of a compromise.  For instance, a small part of a block may be
+getting hit a lot, yet the whole block will be promoted to the cache.
+So large block sizes are bad because they waste cache space.  And small
+block sizes are bad because they increase the amount of metadata (both
+in core and on disk).
+
+Cache operating modes
+---------------------
+
+The cache has three operating modes: writeback, writethrough and
+passthrough.
+
+If writeback, the default, is selected then a write to a block that is
+cached will go only to the cache and the block will be marked dirty in
+the metadata.
+
+If writethrough is selected then a write to a cached block will not
+complete until it has hit both the origin and cache devices.  Clean
+blocks should remain clean.
+
+If passthrough is selected, useful when the cache contents are not known
+to be coherent with the origin device, then all reads are served from
+the origin device (all reads miss the cache) and all writes are
+forwarded to the origin device; additionally, write hits cause cache
+block invalidates.  To enable passthrough mode the cache must be clean.
+Passthrough mode allows a cache device to be activated without having to
+worry about coherency.  Coherency that exists is maintained, although
+the cache will gradually cool as writes take place.  If the coherency of
+the cache can later be verified, or established through use of the
+"invalidate_cblocks" message, the cache device can be transitioned to
+writethrough or writeback mode while still warm.  Otherwise, the cache
+contents can be discarded prior to transitioning to the desired
+operating mode.
+
+A simple cleaner policy is provided, which will clean (write back) all
+dirty blocks in a cache.  Useful for decommissioning a cache or when
+shrinking a cache.  Shrinking the cache's fast device requires all cache
+blocks, in the area of the cache being removed, to be clean.  If the
+area being removed from the cache still contains dirty blocks the resize
+will fail.  Care must be taken to never reduce the volume used for the
+cache's fast device until the cache is clean.  This is of particular
+importance if writeback mode is used.  Writethrough and passthrough
+modes already maintain a clean cache.  Future support to partially clean
+the cache, above a specified threshold, will allow for keeping the cache
+warm and in writeback mode during resize.
+
+Migration throttling
+--------------------
+
+Migrating data between the origin and cache device uses bandwidth.
+The user can set a throttle to prevent more than a certain amount of
+migration occurring at any one time.  Currently we're not taking any
+account of normal io traffic going to the devices.  More work needs
+doing here to avoid migrating during those peak io moments.
+
+For the time being, a message "migration_threshold <#sectors>"
+can be used to set the maximum number of sectors being migrated,
+the default being 2048 sectors (1MB).
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written.
+If no such requests are made then commits will occur every second.  This
+means the cache behaves like a physical disk that has a volatile write
+cache.  If power is lost you may lose some recent writes.  The metadata
+should always be consistent in spite of any crash.
+
+The 'dirty' state for a cache block changes far too frequently for us
+to keep updating it on the fly.  So we treat it as a hint.  In normal
+operation it will be written when the dm device is suspended.  If the
+system crashes all cache blocks will be assumed dirty when restarted.
+
+Per-block policy hints
+----------------------
+
+Policy plug-ins can store a chunk of data per cache block.  It's up to
+the policy how big this chunk is, but it should be kept small.  Like the
+dirty flags this data is lost if there's a crash so a safe fallback
+value should always be possible.
+
+Policy hints affect performance, not correctness.
+
+Policy messaging
+----------------
+
+Policies will have different tunables, specific to each one, so we
+need a generic way of getting and setting these.  Device-mapper
+messages are used.  Refer to cache-policies.txt.
+
+Discard bitset resolution
+-------------------------
+
+We can avoid copying data during migration if we know the block has
+been discarded.  A prime example of this is when mkfs discards the
+whole block device.  We store a bitset tracking the discard state of
+blocks.  However, we allow this bitset to have a different block size
+from the cache blocks.  This is because we need to track the discard
+state for all of the origin device (compare with the dirty bitset
+which is just for the smaller cache device).
+
+Target interface
+================
+
+Constructor
+-----------
+
+  ::
+
+   cache <metadata dev> <cache dev> <origin dev> <block size>
+         <#feature args> [<feature arg>]*
+         <policy> <#policy args> [policy args]*
+
+ ================ =======================================================
+ metadata dev     fast device holding the persistent metadata
+ cache dev	  fast device holding cached data blocks
+ origin dev	  slow device holding original data blocks
+ block size       cache unit size in sectors
+
+ #feature args    number of feature arguments passed
+ feature args     writethrough or passthrough (The default is writeback.)
+
+ policy           the replacement policy to use
+ #policy args     an even number of arguments corresponding to
+                  key/value pairs passed to the policy
+ policy args      key/value pairs passed to the policy
+		  E.g. 'sequential_threshold 1024'
+		  See cache-policies.txt for details.
+ ================ =======================================================
+
+Optional feature arguments are:
+
+
+   ==================== ========================================================
+   writethrough		write through caching that prohibits cache block
+			content from being different from origin block content.
+			Without this argument, the default behaviour is to write
+			back cache block contents later for performance reasons,
+			so they may differ from the corresponding origin blocks.
+
+   passthrough		a degraded mode useful for various cache coherency
+			situations (e.g., rolling back snapshots of
+			underlying storage).	 Reads and writes always go to
+			the origin.	If a write goes to a cached origin
+			block, then the cache block is invalidated.
+			To enable passthrough mode the cache must be clean.
+
+   metadata2		use version 2 of the metadata.  This stores the dirty
+			bits in a separate btree, which improves speed of
+			shutting down the cache.
+
+   no_discard_passdown	disable passing down discards from the cache
+			to the origin's data device.
+   ==================== ========================================================
+
+A policy called 'default' is always registered.  This is an alias for
+the policy we currently think is giving best all round performance.
+
+As the default policy could vary between kernels, if you are relying on
+the characteristics of a specific policy, always request it by name.
+
+Status
+------
+
+::
+
+  <metadata block size> <#used metadata blocks>/<#total metadata blocks>
+  <cache block size> <#used cache blocks>/<#total cache blocks>
+  <#read hits> <#read misses> <#write hits> <#write misses>
+  <#demotions> <#promotions> <#dirty> <#features> <features>*
+  <#core args> <core args>* <policy name> <#policy args> <policy args>*
+  <cache metadata mode>
+
+
+========================= =====================================================
+metadata block size	  Fixed block size for each metadata block in
+			  sectors
+#used metadata blocks	  Number of metadata blocks used
+#total metadata blocks	  Total number of metadata blocks
+cache block size	  Configurable block size for the cache device
+			  in sectors
+#used cache blocks	  Number of blocks resident in the cache
+#total cache blocks	  Total number of cache blocks
+#read hits		  Number of times a READ bio has been mapped
+			  to the cache
+#read misses		  Number of times a READ bio has been mapped
+			  to the origin
+#write hits		  Number of times a WRITE bio has been mapped
+			  to the cache
+#write misses		  Number of times a WRITE bio has been
+			  mapped to the origin
+#demotions		  Number of times a block has been removed
+			  from the cache
+#promotions		  Number of times a block has been moved to
+			  the cache
+#dirty			  Number of blocks in the cache that differ
+			  from the origin
+#feature args		  Number of feature args to follow
+feature args		  'writethrough' (optional)
+#core args		  Number of core arguments (must be even)
+core args		  Key/value pairs for tuning the core
+			  e.g. migration_threshold
+policy name		  Name of the policy
+#policy args		  Number of policy arguments to follow (must be even)
+policy args		  Key/value pairs e.g. sequential_threshold
+cache metadata mode       ro if read-only, rw if read-write
+
+			  In serious cases where even a read-only mode is
+			  deemed unsafe no further I/O will be permitted and
+			  the status will just contain the string 'Fail'.
+			  The userspace recovery tools should then be used.
+needs_check		  'needs_check' if set, '-' if not set
+			  A metadata operation has failed, resulting in the
+			  needs_check flag being set in the metadata's
+			  superblock.  The metadata device must be
+			  deactivated and checked/repaired before the
+			  cache can be made fully operational again.
+			  '-' indicates	needs_check is not set.
+========================= =====================================================
+
+Messages
+--------
+
+Policies will have different tunables, specific to each one, so we
+need a generic way of getting and setting these.  Device-mapper
+messages are used.  (A sysfs interface would also be possible.)
+
+The message format is::
+
+   <key> <value>
+
+E.g.::
+
+   dmsetup message my_cache 0 sequential_threshold 1024
+
+
+Invalidation is removing an entry from the cache without writing it
+back.  Cache blocks can be invalidated via the invalidate_cblocks
+message, which takes an arbitrary number of cblock ranges.  Each cblock
+range's end value is "one past the end", meaning 5-10 expresses a range
+of values from 5 to 9.  Each cblock must be expressed as a decimal
+value, in the future a variant message that takes cblock ranges
+expressed in hexadecimal may be needed to better support efficient
+invalidation of larger caches.  The cache must be in passthrough mode
+when invalidate_cblocks is used::
+
+   invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]*
+
+E.g.::
+
+   dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789
+
+Examples
+========
+
+The test suite can be found here:
+
+https://github.com/jthornber/device-mapper-test-suite
+
+::
+
+  dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
+	  /dev/mapper/ssd /dev/mapper/origin 512 1 writeback default 0'
+  dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
+	  /dev/mapper/ssd /dev/mapper/origin 1024 1 writeback \
+	  mq 4 sequential_threshold 1024 random_threshold 8'
diff --git a/Documentation/admin-guide/device-mapper/delay.rst b/Documentation/admin-guide/device-mapper/delay.rst
new file mode 100644
index 000000000..a1e673c0e
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/delay.rst
@@ -0,0 +1,54 @@
+========
+dm-delay
+========
+
+Device-Mapper's "delay" target delays reads and/or writes
+and/or flushes and optionally maps them to different devices.
+
+Arguments::
+
+    <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
+			       [<flush_device> <flush_offset> <flush_delay>]]
+
+Table line has to either have 3, 6 or 9 arguments:
+
+3: apply offset and delay to read, write and flush operations on device
+
+6: apply offset and delay to device, also apply write_offset and write_delay
+   to write and flush operations on optionally different write_device with
+   optionally different sector offset
+
+9: same as 6 arguments plus define flush_offset and flush_delay explicitly
+   on/with optionally different flush_device/flush_offset.
+
+Offsets are specified in sectors.
+
+Delays are specified in milliseconds.
+
+
+Example scripts
+===============
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device named "delayed" delaying read, write and flush operations for 500ms.
+	#
+	dmsetup create delayed --table  "0 `blockdev --getsz $1` delay $1 0 500"
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device delaying write and flush operations for 400ms and
+	# splitting reads to device $1 but writes and flushes to different device $2
+	# to different offsets of 2048 and 4096 sectors respectively.
+	#
+	dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 2048 0 $2 4096 400"
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device delaying reads for 50ms, writes for 100ms and flushes for 333ms
+	# onto the same backing device at offset 0 sectors.
+	#
+	dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 50 $2 0 100 $1 0 333"
diff --git a/Documentation/admin-guide/device-mapper/dm-clone.rst b/Documentation/admin-guide/device-mapper/dm-clone.rst
new file mode 100644
index 000000000..b43a34c14
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-clone.rst
@@ -0,0 +1,333 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+========
+dm-clone
+========
+
+Introduction
+============
+
+dm-clone is a device mapper target which produces a one-to-one copy of an
+existing, read-only source device into a writable destination device: It
+presents a virtual block device which makes all data appear immediately, and
+redirects reads and writes accordingly.
+
+The main use case of dm-clone is to clone a potentially remote, high-latency,
+read-only, archival-type block device into a writable, fast, primary-type device
+for fast, low-latency I/O. The cloned device is visible/mountable immediately
+and the copy of the source device to the destination device happens in the
+background, in parallel with user I/O.
+
+For example, one could restore an application backup from a read-only copy,
+accessible through a network storage protocol (NBD, Fibre Channel, iSCSI, AoE,
+etc.), into a local SSD or NVMe device, and start using the device immediately,
+without waiting for the restore to complete.
+
+When the cloning completes, the dm-clone table can be removed altogether and be
+replaced, e.g., by a linear table, mapping directly to the destination device.
+
+The dm-clone target reuses the metadata library used by the thin-provisioning
+target.
+
+Glossary
+========
+
+   Hydration
+     The process of filling a region of the destination device with data from
+     the same region of the source device, i.e., copying the region from the
+     source to the destination device.
+
+Once a region gets hydrated we redirect all I/O regarding it to the destination
+device.
+
+Design
+======
+
+Sub-devices
+-----------
+
+The target is constructed by passing three devices to it (along with other
+parameters detailed later):
+
+1. A source device - the read-only device that gets cloned and source of the
+   hydration.
+
+2. A destination device - the destination of the hydration, which will become a
+   clone of the source device.
+
+3. A small metadata device - it records which regions are already valid in the
+   destination device, i.e., which regions have already been hydrated, or have
+   been written to directly, via user I/O.
+
+The size of the destination device must be at least equal to the size of the
+source device.
+
+Regions
+-------
+
+dm-clone divides the source and destination devices in fixed sized regions.
+Regions are the unit of hydration, i.e., the minimum amount of data copied from
+the source to the destination device.
+
+The region size is configurable when you first create the dm-clone device. The
+recommended region size is the same as the file system block size, which usually
+is 4KB. The region size must be between 8 sectors (4KB) and 2097152 sectors
+(1GB) and a power of two.
+
+Reads and writes from/to hydrated regions are serviced from the destination
+device.
+
+A read to a not yet hydrated region is serviced directly from the source device.
+
+A write to a not yet hydrated region will be delayed until the corresponding
+region has been hydrated and the hydration of the region starts immediately.
+
+Note that a write request with size equal to region size will skip copying of
+the corresponding region from the source device and overwrite the region of the
+destination device directly.
+
+Discards
+--------
+
+dm-clone interprets a discard request to a range that hasn't been hydrated yet
+as a hint to skip hydration of the regions covered by the request, i.e., it
+skips copying the region's data from the source to the destination device, and
+only updates its metadata.
+
+If the destination device supports discards, then by default dm-clone will pass
+down discard requests to it.
+
+Background Hydration
+--------------------
+
+dm-clone copies continuously from the source to the destination device, until
+all of the device has been copied.
+
+Copying data from the source to the destination device uses bandwidth. The user
+can set a throttle to prevent more than a certain amount of copying occurring at
+any one time. Moreover, dm-clone takes into account user I/O traffic going to
+the devices and pauses the background hydration when there is I/O in-flight.
+
+A message `hydration_threshold <#regions>` can be used to set the maximum number
+of regions being copied, the default being 1 region.
+
+dm-clone employs dm-kcopyd for copying portions of the source device to the
+destination device. By default, we issue copy requests of size equal to the
+region size. A message `hydration_batch_size <#regions>` can be used to tune the
+size of these copy requests. Increasing the hydration batch size results in
+dm-clone trying to batch together contiguous regions, so we copy the data in
+batches of this many regions.
+
+When the hydration of the destination device finishes, a dm event will be sent
+to user space.
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written. If no
+such requests are made then commits will occur every second. This means the
+dm-clone device behaves like a physical disk that has a volatile write cache. If
+power is lost you may lose some recent writes. The metadata should always be
+consistent in spite of any crash.
+
+Target Interface
+================
+
+Constructor
+-----------
+
+  ::
+
+   clone <metadata dev> <destination dev> <source dev> <region size>
+         [<#feature args> [<feature arg>]* [<#core args> [<core arg>]*]]
+
+ ================ ==============================================================
+ metadata dev     Fast device holding the persistent metadata
+ destination dev  The destination device, where the source will be cloned
+ source dev       Read only device containing the data that gets cloned
+ region size      The size of a region in sectors
+
+ #feature args    Number of feature arguments passed
+ feature args     no_hydration or no_discard_passdown
+
+ #core args       An even number of arguments corresponding to key/value pairs
+                  passed to dm-clone
+ core args        Key/value pairs passed to dm-clone, e.g. `hydration_threshold
+                  256`
+ ================ ==============================================================
+
+Optional feature arguments are:
+
+ ==================== =========================================================
+ no_hydration         Create a dm-clone instance with background hydration
+                      disabled
+ no_discard_passdown  Disable passing down discards to the destination device
+ ==================== =========================================================
+
+Optional core arguments are:
+
+ ================================ ==============================================
+ hydration_threshold <#regions>   Maximum number of regions being copied from
+                                  the source to the destination device at any
+                                  one time, during background hydration.
+ hydration_batch_size <#regions>  During background hydration, try to batch
+                                  together contiguous regions, so we copy data
+                                  from the source to the destination device in
+                                  batches of this many regions.
+ ================================ ==============================================
+
+Status
+------
+
+  ::
+
+   <metadata block size> <#used metadata blocks>/<#total metadata blocks>
+   <region size> <#hydrated regions>/<#total regions> <#hydrating regions>
+   <#feature args> <feature args>* <#core args> <core args>*
+   <clone metadata mode>
+
+ ======================= =======================================================
+ metadata block size     Fixed block size for each metadata block in sectors
+ #used metadata blocks   Number of metadata blocks used
+ #total metadata blocks  Total number of metadata blocks
+ region size             Configurable region size for the device in sectors
+ #hydrated regions       Number of regions that have finished hydrating
+ #total regions          Total number of regions to hydrate
+ #hydrating regions      Number of regions currently hydrating
+ #feature args           Number of feature arguments to follow
+ feature args            Feature arguments, e.g. `no_hydration`
+ #core args              Even number of core arguments to follow
+ core args               Key/value pairs for tuning the core, e.g.
+                         `hydration_threshold 256`
+ clone metadata mode     ro if read-only, rw if read-write
+
+                         In serious cases where even a read-only mode is deemed
+                         unsafe no further I/O will be permitted and the status
+                         will just contain the string 'Fail'. If the metadata
+                         mode changes, a dm event will be sent to user space.
+ ======================= =======================================================
+
+Messages
+--------
+
+  `disable_hydration`
+      Disable the background hydration of the destination device.
+
+  `enable_hydration`
+      Enable the background hydration of the destination device.
+
+  `hydration_threshold <#regions>`
+      Set background hydration threshold.
+
+  `hydration_batch_size <#regions>`
+      Set background hydration batch size.
+
+Examples
+========
+
+Clone a device containing a file system
+---------------------------------------
+
+1. Create the dm-clone device.
+
+   ::
+
+    dmsetup create clone --table "0 1048576000 clone $metadata_dev $dest_dev \
+      $source_dev 8 1 no_hydration"
+
+2. Mount the device and trim the file system. dm-clone interprets the discards
+   sent by the file system and it will not hydrate the unused space.
+
+   ::
+
+    mount /dev/mapper/clone /mnt/cloned-fs
+    fstrim /mnt/cloned-fs
+
+3. Enable background hydration of the destination device.
+
+   ::
+
+    dmsetup message clone 0 enable_hydration
+
+4. When the hydration finishes, we can replace the dm-clone table with a linear
+   table.
+
+   ::
+
+    dmsetup suspend clone
+    dmsetup load clone --table "0 1048576000 linear $dest_dev 0"
+    dmsetup resume clone
+
+   The metadata device is no longer needed and can be safely discarded or reused
+   for other purposes.
+
+Known issues
+============
+
+1. We redirect reads, to not-yet-hydrated regions, to the source device. If
+   reading the source device has high latency and the user repeatedly reads from
+   the same regions, this behaviour could degrade performance. We should use
+   these reads as hints to hydrate the relevant regions sooner. Currently, we
+   rely on the page cache to cache these regions, so we hopefully don't end up
+   reading them multiple times from the source device.
+
+2. Release in-core resources, i.e., the bitmaps tracking which regions are
+   hydrated, after the hydration has finished.
+
+3. During background hydration, if we fail to read the source or write to the
+   destination device, we print an error message, but the hydration process
+   continues indefinitely, until it succeeds. We should stop the background
+   hydration after a number of failures and emit a dm event for user space to
+   notice.
+
+Why not...?
+===========
+
+We explored the following alternatives before implementing dm-clone:
+
+1. Use dm-cache with cache size equal to the source device and implement a new
+   cloning policy:
+
+   * The resulting cache device is not a one-to-one mirror of the source device
+     and thus we cannot remove the cache device once cloning completes.
+
+   * dm-cache writes to the source device, which violates our requirement that
+     the source device must be treated as read-only.
+
+   * Caching is semantically different from cloning.
+
+2. Use dm-snapshot with a COW device equal to the source device:
+
+   * dm-snapshot stores its metadata in the COW device, so the resulting device
+     is not a one-to-one mirror of the source device.
+
+   * No background copying mechanism.
+
+   * dm-snapshot needs to commit its metadata whenever a pending exception
+     completes, to ensure snapshot consistency. In the case of cloning, we don't
+     need to be so strict and can rely on committing metadata every time a FLUSH
+     or FUA bio is written, or periodically, like dm-thin and dm-cache do. This
+     improves the performance significantly.
+
+3. Use dm-mirror: The mirror target has a background copying/mirroring
+   mechanism, but it writes to all mirrors, thus violating our requirement that
+   the source device must be treated as read-only.
+
+4. Use dm-thin's external snapshot functionality. This approach is the most
+   promising among all alternatives, as the thinly-provisioned volume is a
+   one-to-one mirror of the source device and handles reads and writes to
+   un-provisioned/not-yet-cloned areas the same way as dm-clone does.
+
+   Still:
+
+   * There is no background copying mechanism, though one could be implemented.
+
+   * Most importantly, we want to support arbitrary block devices as the
+     destination of the cloning process and not restrict ourselves to
+     thinly-provisioned volumes. Thin-provisioning has an inherent metadata
+     overhead, for maintaining the thin volume mappings, which significantly
+     degrades performance.
+
+   Moreover, cloning a device shouldn't force the use of thin-provisioning. On
+   the other hand, if we wish to use thin provisioning, we can just use a thin
+   LV as dm-clone's destination device.
diff --git a/Documentation/admin-guide/device-mapper/dm-crypt.rst b/Documentation/admin-guide/device-mapper/dm-crypt.rst
new file mode 100644
index 000000000..4467f6d4b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-crypt.rst
@@ -0,0 +1,212 @@
+========
+dm-crypt
+========
+
+Device-Mapper's "crypt" target provides transparent encryption of block devices
+using the kernel crypto API.
+
+For a more detailed description of supported parameters see:
+https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt
+
+Parameters::
+
+	      <cipher> <key> <iv_offset> <device path> \
+	      <offset> [<#opt_params> <opt_params>]
+
+<cipher>
+    Encryption cipher, encryption mode and Initial Vector (IV) generator.
+
+    The cipher specifications format is::
+
+       cipher[:keycount]-chainmode-ivmode[:ivopts]
+
+    Examples::
+
+       aes-cbc-essiv:sha256
+       aes-xts-plain64
+       serpent-xts-plain64
+
+    Cipher format also supports direct specification with kernel crypt API
+    format (selected by capi: prefix). The IV specification is the same
+    as for the first format type.
+    This format is mainly used for specification of authenticated modes.
+
+    The crypto API cipher specifications format is::
+
+        capi:cipher_api_spec-ivmode[:ivopts]
+
+    Examples::
+
+        capi:cbc(aes)-essiv:sha256
+        capi:xts(aes)-plain64
+
+    Examples of authenticated modes::
+
+        capi:gcm(aes)-random
+        capi:authenc(hmac(sha256),xts(aes))-random
+        capi:rfc7539(chacha20,poly1305)-random
+
+    The /proc/crypto contains a list of currently loaded crypto modes.
+
+<key>
+    Key used for encryption. It is encoded either as a hexadecimal number
+    or it can be passed as <key_string> prefixed with single colon
+    character (':') for keys residing in kernel keyring service.
+    You can only use key sizes that are valid for the selected cipher
+    in combination with the selected iv mode.
+    Note that for some iv modes the key string can contain additional
+    keys (for example IV seed) so the key contains more parts concatenated
+    into a single string.
+
+<key_string>
+    The kernel keyring key is identified by string in following format:
+    <key_size>:<key_type>:<key_description>.
+
+<key_size>
+    The encryption key size in bytes. The kernel key payload size must match
+    the value passed in <key_size>.
+
+<key_type>
+    Either 'logon', 'user', 'encrypted' or 'trusted' kernel key type.
+
+<key_description>
+    The kernel keyring key description crypt target should look for
+    when loading key of <key_type>.
+
+<keycount>
+    Multi-key compatibility mode. You can define <keycount> keys and
+    then sectors are encrypted according to their offsets (sector 0 uses key0;
+    sector 1 uses key1 etc.).  <keycount> must be a power of two.
+
+<iv_offset>
+    The IV offset is a sector count that is added to the sector number
+    before creating the IV.
+
+<device path>
+    This is the device that is going to be used as backend and contains the
+    encrypted data.  You can specify it as a path like /dev/xxx or a device
+    number <major>:<minor>.
+
+<offset>
+    Starting sector within the device where the encrypted data begins.
+
+<#opt_params>
+    Number of optional parameters. If there are no optional parameters,
+    the optional parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        3 allow_discards same_cpu_crypt submit_from_crypt_cpus
+
+allow_discards
+    Block discard requests (a.k.a. TRIM) are passed through the crypt device.
+    The default is to ignore discard requests.
+
+    WARNING: Assess the specific security risks carefully before enabling this
+    option.  For example, allowing discards on encrypted devices may lead to
+    the leak of information about the ciphertext device (filesystem type,
+    used space etc.) if the discarded blocks can be located easily on the
+    device later.
+
+same_cpu_crypt
+    Perform encryption using the same cpu that IO was submitted on.
+    The default is to use an unbound workqueue so that encryption work
+    is automatically balanced between available CPUs.
+
+high_priority
+    Set dm-crypt workqueues and the writer thread to high priority. This
+    improves throughput and latency of dm-crypt while degrading general
+    responsiveness of the system.
+
+submit_from_crypt_cpus
+    Disable offloading writes to a separate thread after encryption.
+    There are some situations where offloading write bios from the
+    encryption threads to a single thread degrades performance
+    significantly.  The default is to offload write bios to the same
+    thread because it benefits CFQ to have writes submitted using the
+    same context.
+
+no_read_workqueue
+    Bypass dm-crypt internal workqueue and process read requests synchronously.
+
+no_write_workqueue
+    Bypass dm-crypt internal workqueue and process write requests synchronously.
+    This option is automatically enabled for host-managed zoned block devices
+    (e.g. host-managed SMR hard-disks).
+
+integrity:<bytes>:<type>
+    The device requires additional <bytes> metadata per-sector stored
+    in per-bio integrity structure. This metadata must by provided
+    by underlying dm-integrity target.
+
+    The <type> can be "none" if metadata is used only for persistent IV.
+
+    For Authenticated Encryption with Additional Data (AEAD)
+    the <type> is "aead". An AEAD mode additionally calculates and verifies
+    integrity for the encrypted device. The additional space is then
+    used for storing authentication tag (and persistent IV if needed).
+
+integrity_key_size:<bytes>
+    Optionally set the integrity key size if it differs from the digest size.
+    It allows the use of wrapped key algorithms where the key size is
+    independent of the cryptographic key size.
+
+sector_size:<bytes>
+    Use <bytes> as the encryption unit instead of 512 bytes sectors.
+    This option can be in range 512 - 4096 bytes and must be power of two.
+    Virtual device will announce this size as a minimal IO and logical sector.
+
+iv_large_sectors
+   IV generators will use sector number counted in <sector_size> units
+   instead of default 512 bytes sectors.
+
+   For example, if <sector_size> is 4096 bytes, plain64 IV for the second
+   sector will be 8 (without flag) and 1 if iv_large_sectors is present.
+   The <iv_offset> must be multiple of <sector_size> (in 512 bytes units)
+   if this flag is specified.
+
+integrity_key_size:<bytes>
+   Use an integrity key of <bytes> size instead of using an integrity key size
+   of the digest size of the used HMAC algorithm.
+
+
+Module parameters::
+   max_read_size
+      Maximum size of read requests. When a request larger than this size
+      is received, dm-crypt will split the request. The splitting improves
+      concurrency (the split requests could be encrypted in parallel by multiple
+      cores), but it also causes overhead. The user should tune this parameters to
+      fit the actual workload.
+
+   max_write_size
+      Maximum size of write requests. When a request larger than this size
+      is received, dm-crypt will split the request. The splitting improves
+      concurrency (the split requests could be encrypted in parallel by multiple
+      cores), but it also causes overhead. The user should tune this parameters to
+      fit the actual workload.
+
+
+Example scripts
+===============
+LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
+encryption with dm-crypt using the 'cryptsetup' utility, see
+https://gitlab.com/cryptsetup/cryptsetup
+
+::
+
+	#!/bin/sh
+	# Create a crypt device using dmsetup
+	dmsetup create crypt1 --table "0 `blockdev --getsz $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
+
+::
+
+	#!/bin/sh
+	# Create a crypt device using dmsetup when encryption key is stored in keyring service
+	dmsetup create crypt2 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 :32:logon:my_prefix:my_key 0 $1 0"
+
+::
+
+	#!/bin/sh
+	# Create a crypt device using cryptsetup and LUKS header with default cipher
+	cryptsetup luksFormat $1
+	cryptsetup luksOpen $1 crypt1
diff --git a/Documentation/admin-guide/device-mapper/dm-dust.rst b/Documentation/admin-guide/device-mapper/dm-dust.rst
new file mode 100644
index 000000000..e35ec8cd2
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-dust.rst
@@ -0,0 +1,305 @@
+dm-dust
+=======
+
+This target emulates the behavior of bad sectors at arbitrary
+locations, and the ability to enable the emulation of the failures
+at an arbitrary time.
+
+This target behaves similarly to a linear target.  At a given time,
+the user can send a message to the target to start failing read
+requests on specific blocks (to emulate the behavior of a hard disk
+drive with bad sectors).
+
+When the failure behavior is enabled (i.e.: when the output of
+"dmsetup status" displays "fail_read_on_bad_block"), reads of blocks
+in the "bad block list" will fail with EIO ("Input/output error").
+
+Writes of blocks in the "bad block list will result in the following:
+
+1. Remove the block from the "bad block list".
+2. Successfully complete the write.
+
+This emulates the "remapped sector" behavior of a drive with bad
+sectors.
+
+Normally, a drive that is encountering bad sectors will most likely
+encounter more bad sectors, at an unknown time or location.
+With dm-dust, the user can use the "addbadblock" and "removebadblock"
+messages to add arbitrary bad blocks at new locations, and the
+"enable" and "disable" messages to modulate the state of whether the
+configured "bad blocks" will be treated as bad, or bypassed.
+This allows the pre-writing of test data and metadata prior to
+simulating a "failure" event where bad sectors start to appear.
+
+Table parameters
+----------------
+<device_path> <offset> <blksz>
+
+Mandatory parameters:
+    <device_path>:
+        Path to the block device.
+
+    <offset>:
+        Offset to data area from start of device_path
+
+    <blksz>:
+        Block size in bytes
+
+	     (minimum 512, maximum 1073741824, must be a power of 2)
+
+Usage instructions
+------------------
+
+First, find the size (in 512-byte sectors) of the device to be used::
+
+        $ sudo blockdev --getsz /dev/vdb1
+        33552384
+
+Create the dm-dust device:
+(For a device with a block size of 512 bytes)
+
+::
+
+        $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 512'
+
+(For a device with a block size of 4096 bytes)
+
+::
+
+        $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 4096'
+
+Check the status of the read behavior ("bypass" indicates that all I/O
+will be passed through to the underlying device; "verbose" indicates that
+bad block additions, removals, and remaps will be verbosely logged)::
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 bypass verbose
+
+        $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=128 iflag=direct
+        128+0 records in
+        128+0 records out
+
+        $ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct
+        128+0 records in
+        128+0 records out
+
+Adding and removing bad blocks
+------------------------------
+
+At any time (i.e.: whether the device has the "bad block" emulation
+enabled or disabled), bad blocks may be added or removed from the
+device via the "addbadblock" and "removebadblock" messages::
+
+        $ sudo dmsetup message dust1 0 addbadblock 60
+        kernel: device-mapper: dust: badblock added at block 60
+
+        $ sudo dmsetup message dust1 0 addbadblock 67
+        kernel: device-mapper: dust: badblock added at block 67
+
+        $ sudo dmsetup message dust1 0 addbadblock 72
+        kernel: device-mapper: dust: badblock added at block 72
+
+These bad blocks will be stored in the "bad block list".
+While the device is in "bypass" mode, reads and writes will succeed::
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 bypass
+
+Enabling block read failures
+----------------------------
+
+To enable the "fail read on bad block" behavior, send the "enable" message::
+
+        $ sudo dmsetup message dust1 0 enable
+        kernel: device-mapper: dust: enabling read failures on bad sectors
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 fail_read_on_bad_block
+
+With the device in "fail read on bad block" mode, attempting to read a
+block will encounter an "Input/output error"::
+
+        $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=1 skip=67 iflag=direct
+        dd: error reading '/dev/mapper/dust1': Input/output error
+        0+0 records in
+        0+0 records out
+        0 bytes copied, 0.00040651 s, 0.0 kB/s
+
+...and writing to the bad blocks will remove the blocks from the list,
+therefore emulating the "remap" behavior of hard disk drives::
+
+        $ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct
+        128+0 records in
+        128+0 records out
+
+        kernel: device-mapper: dust: block 60 removed from badblocklist by write
+        kernel: device-mapper: dust: block 67 removed from badblocklist by write
+        kernel: device-mapper: dust: block 72 removed from badblocklist by write
+        kernel: device-mapper: dust: block 87 removed from badblocklist by write
+
+Bad block add/remove error handling
+-----------------------------------
+
+Attempting to add a bad block that already exists in the list will
+result in an "Invalid argument" error, as well as a helpful message::
+
+        $ sudo dmsetup message dust1 0 addbadblock 88
+        device-mapper: message ioctl on dust1  failed: Invalid argument
+        kernel: device-mapper: dust: block 88 already in badblocklist
+
+Attempting to remove a bad block that doesn't exist in the list will
+result in an "Invalid argument" error, as well as a helpful message::
+
+        $ sudo dmsetup message dust1 0 removebadblock 87
+        device-mapper: message ioctl on dust1  failed: Invalid argument
+        kernel: device-mapper: dust: block 87 not found in badblocklist
+
+Counting the number of bad blocks in the bad block list
+-------------------------------------------------------
+
+To count the number of bad blocks configured in the device, run the
+following message command::
+
+        $ sudo dmsetup message dust1 0 countbadblocks
+
+A message will print with the number of bad blocks currently
+configured on the device::
+
+        countbadblocks: 895 badblock(s) found
+
+Querying for specific bad blocks
+--------------------------------
+
+To find out if a specific block is in the bad block list, run the
+following message command::
+
+        $ sudo dmsetup message dust1 0 queryblock 72
+
+The following message will print if the block is in the list::
+
+        dust_query_block: block 72 found in badblocklist
+
+The following message will print if the block is not in the list::
+
+        dust_query_block: block 72 not found in badblocklist
+
+The "queryblock" message command will work in both the "enabled"
+and "disabled" modes, allowing the verification of whether a block
+will be treated as "bad" without having to issue I/O to the device,
+or having to "enable" the bad block emulation.
+
+Clearing the bad block list
+---------------------------
+
+To clear the bad block list (without needing to individually run
+a "removebadblock" message command for every block), run the
+following message command::
+
+        $ sudo dmsetup message dust1 0 clearbadblocks
+
+After clearing the bad block list, the following message will appear::
+
+        dust_clear_badblocks: badblocks cleared
+
+If there were no bad blocks to clear, the following message will
+appear::
+
+        dust_clear_badblocks: no badblocks found
+
+Listing the bad block list
+--------------------------
+
+To list all bad blocks in the bad block list (using an example device
+with blocks 1 and 2 in the bad block list), run the following message
+command::
+
+        $ sudo dmsetup message dust1 0 listbadblocks
+        1
+        2
+
+If there are no bad blocks in the bad block list, the command will
+execute with no output::
+
+        $ sudo dmsetup message dust1 0 listbadblocks
+
+Message commands list
+---------------------
+
+Below is a list of the messages that can be sent to a dust device:
+
+Operations on blocks (requires a <blknum> argument)::
+
+        addbadblock <blknum>
+        queryblock <blknum>
+        removebadblock <blknum>
+
+...where <blknum> is a block number within range of the device
+(corresponding to the block size of the device.)
+
+Single argument message commands::
+
+        countbadblocks
+        clearbadblocks
+        listbadblocks
+        disable
+        enable
+        quiet
+
+Device removal
+--------------
+
+When finished, remove the device via the "dmsetup remove" command::
+
+        $ sudo dmsetup remove dust1
+
+Quiet mode
+----------
+
+On test runs with many bad blocks, it may be desirable to avoid
+excessive logging (from bad blocks added, removed, or "remapped").
+This can be done by enabling "quiet mode" via the following message::
+
+        $ sudo dmsetup message dust1 0 quiet
+
+This will suppress log messages from add / remove / removed by write
+operations.  Log messages from "countbadblocks" or "queryblock"
+message commands will still print in quiet mode.
+
+The status of quiet mode can be seen by running "dmsetup status"::
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 fail_read_on_bad_block quiet
+
+To disable quiet mode, send the "quiet" message again::
+
+        $ sudo dmsetup message dust1 0 quiet
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 fail_read_on_bad_block verbose
+
+(The presence of "verbose" indicates normal logging.)
+
+"Why not...?"
+-------------
+
+scsi_debug has a "medium error" mode that can fail reads on one
+specified sector (sector 0x1234, hardcoded in the source code), but
+it uses RAM for the persistent storage, which drastically decreases
+the potential device size.
+
+dm-flakey fails all I/O from all block locations at a specified time
+frequency, and not a given point in time.
+
+When a bad sector occurs on a hard disk drive, reads to that sector
+are failed by the device, usually resulting in an error code of EIO
+("I/O error") or ENODATA ("No data available").  However, a write to
+the sector may succeed, and result in the sector becoming readable
+after the device controller no longer experiences errors reading the
+sector (or after a reallocation of the sector).  However, there may
+be bad sectors that occur on the device in the future, in a different,
+unpredictable location.
+
+This target seeks to provide a device that can exhibit the behavior
+of a bad sector at a known sector location, at a known time, based
+on a large storage device (at least tens of gigabytes, not occupying
+system memory).
diff --git a/Documentation/admin-guide/device-mapper/dm-ebs.rst b/Documentation/admin-guide/device-mapper/dm-ebs.rst
new file mode 100644
index 000000000..c09f66db5
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ebs.rst
@@ -0,0 +1,51 @@
+======
+dm-ebs
+======
+
+
+This target is similar to the linear target except that it emulates
+a smaller logical block size on a device with a larger logical block
+size.  Its main purpose is to provide emulation of 512 byte sectors on
+devices that do not provide this emulation (i.e. 4K native disks).
+
+Supported emulated logical block sizes 512, 1024, 2048 and 4096.
+
+Underlying block size can be set to > 4K to test buffering larger units.
+
+
+Table parameters
+----------------
+  <dev path> <offset> <emulated sectors> [<underlying sectors>]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device,
+        or a "major:minor" device-number.
+    <offset>:
+        Starting sector within the device;
+        has to be a multiple of <emulated sectors>.
+    <emulated sectors>:
+        Number of sectors defining the logical block size to be emulated;
+        1, 2, 4, 8 sectors of 512 bytes supported.
+
+Optional parameter:
+
+    <underlying sectors>:
+        Number of sectors defining the logical block size of <dev path>.
+        2^N supported, e.g. 8 = emulate 8 sectors of 512 bytes = 4KiB.
+        If not provided, the logical block size of <dev path> will be used.
+
+
+Examples:
+
+Emulate 1 sector = 512 bytes logical block size on /dev/sda starting at
+offset 1024 sectors with underlying devices block size automatically set:
+
+ebs /dev/sda 1024 1
+
+Emulate 2 sector = 1KiB logical block size on /dev/sda starting at
+offset 128 sectors, enforce 2KiB underlying device block size.
+This presumes 2KiB logical blocksize on /dev/sda or less to work:
+
+ebs /dev/sda 128 2 4
diff --git a/Documentation/admin-guide/device-mapper/dm-flakey.rst b/Documentation/admin-guide/device-mapper/dm-flakey.rst
new file mode 100644
index 000000000..f967c5fea
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-flakey.rst
@@ -0,0 +1,88 @@
+=========
+dm-flakey
+=========
+
+This target is the same as the linear target except that it exhibits
+unreliable behaviour periodically.  It's been found useful in simulating
+failing devices for testing purposes.
+
+Starting from the time the table is loaded, the device is available for
+<up interval> seconds, then exhibits unreliable behaviour for <down
+interval> seconds, and then this cycle repeats.
+
+Also, consider using this in combination with the dm-delay target too,
+which can delay reads and writes and/or send them to different
+underlying devices.
+
+Table parameters
+----------------
+
+::
+
+  <dev path> <offset> <up interval> <down interval> \
+    [<num_features> [<feature arguments>]]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device, or a
+        "major:minor" device-number.
+    <offset>:
+        Starting sector within the device.
+    <up interval>:
+        Number of seconds device is available.
+    <down interval>:
+        Number of seconds device returns errors.
+
+Optional feature parameters:
+
+  If no feature parameters are present, during the periods of
+  unreliability, all I/O returns errors.
+
+  error_reads:
+	All read I/O is failed with an error signalled.
+	Write I/O is handled correctly.
+
+  drop_writes:
+	All write I/O is silently ignored.
+	Read I/O is handled correctly.
+
+  error_writes:
+	All write I/O is failed with an error signalled.
+	Read I/O is handled correctly.
+
+  corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
+	During <down interval>, replace <Nth_byte> of the data of
+	each matching bio with <value>.
+
+    <Nth_byte>:
+	The offset of the byte to replace.
+	Counting starts at 1, to replace the first byte.
+    <direction>:
+	Either 'r' to corrupt reads or 'w' to corrupt writes.
+	'w' is incompatible with drop_writes.
+    <value>:
+	The value (from 0-255) to write.
+    <flags>:
+	Perform the replacement only if bio->bi_opf has all the
+	selected flags set.
+
+  random_read_corrupt <probability>
+	During <down interval>, replace random byte in a read bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+  random_write_corrupt <probability>
+	During <down interval>, replace random byte in a write bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+Examples:
+
+Replaces the 32nd byte of READ bios with the value 1::
+
+  corrupt_bio_byte 32 r 1 0
+
+Replaces the 224th byte of REQ_META (=32) bios with the value 0::
+
+  corrupt_bio_byte 224 w 0 32
diff --git a/Documentation/admin-guide/device-mapper/dm-ima.rst b/Documentation/admin-guide/device-mapper/dm-ima.rst
new file mode 100644
index 000000000..2a3b50ffb
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ima.rst
@@ -0,0 +1,718 @@
+======
+dm-ima
+======
+
+For a given system, various external services/infrastructure tools
+(including the attestation service) interact with it - both during the
+setup and during rest of the system run-time.  They share sensitive data
+and/or execute critical workload on that system.  The external services
+may want to verify the current run-time state of the relevant kernel
+subsystems before fully trusting the system with business-critical
+data/workload.
+
+Device mapper plays a critical role on a given system by providing
+various important functionalities to the block devices using various
+target types like crypt, verity, integrity etc.  Each of these target
+types’ functionalities can be configured with various attributes.
+The attributes chosen to configure these target types can significantly
+impact the security profile of the block device, and in-turn, of the
+system itself.  For instance, the type of encryption algorithm and the
+key size determines the strength of encryption for a given block device.
+
+Therefore, verifying the current state of various block devices as well
+as their various target attributes is crucial for external services before
+fully trusting the system with business-critical data/workload.
+
+IMA kernel subsystem provides the necessary functionality for
+device mapper to measure the state and configuration of
+various block devices -
+
+- by device mapper itself, from within the kernel,
+- in a tamper resistant way,
+- and re-measured - triggered on state/configuration change.
+
+Setting the IMA Policy:
+=======================
+For IMA to measure the data on a given system, the IMA policy on the
+system needs to be updated to have following line, and the system needs
+to be restarted for the measurements to take effect.
+
+::
+
+ /etc/ima/ima-policy
+    measure func=CRITICAL_DATA label=device-mapper template=ima-buf
+
+The measurements will be reflected in the IMA logs, which are located at:
+
+::
+
+ /sys/kernel/security/integrity/ima/ascii_runtime_measurements
+ /sys/kernel/security/integrity/ima/binary_runtime_measurements
+
+Then IMA ASCII measurement log has the following format:
+
+::
+
+ <PCR> <TEMPLATE_DATA_DIGEST> <TEMPLATE_NAME> <TEMPLATE_DATA>
+
+ PCR := Platform Configuration Register, in which the values are registered.
+       This is applicable if TPM chip is in use.
+
+ TEMPLATE_DATA_DIGEST := Template data digest of the IMA record.
+ TEMPLATE_NAME := Template name that registered the integrity value (e.g. ima-buf).
+
+ TEMPLATE_DATA := <ALG> ":" <EVENT_DIGEST> <EVENT_NAME> <EVENT_DATA>
+                  It contains data for the specific event to be measured,
+                  in a given template data format.
+
+ ALG := Algorithm to compute event digest
+ EVENT_DIGEST := Digest of the event data
+ EVENT_NAME := Description of the event (e.g. 'dm_table_load').
+ EVENT_DATA := The event data to be measured.
+
+|
+
+| *NOTE #1:*
+| The DM target data measured by IMA subsystem can alternatively
+ be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with
+ DM_TABLE_STATUS_CMD.
+
+|
+
+| *NOTE #2:*
+| The Kernel configuration CONFIG_IMA_DISABLE_HTABLE allows measurement of duplicate records.
+| To support recording duplicate IMA events in the IMA log, the Kernel needs to be configured with
+ CONFIG_IMA_DISABLE_HTABLE=y.
+
+Supported Device States:
+========================
+Following device state changes will trigger IMA measurements:
+
+ 1. Table load
+ #. Device resume
+ #. Device remove
+ #. Table clear
+ #. Device rename
+
+1. Table load:
+---------------
+When a new table is loaded in a device's inactive table slot,
+the device information and target specific details from the
+targets in the table are measured.
+
+The IMA measurement log has the following format for 'dm_table_load':
+
+::
+
+ EVENT_NAME := "dm_table_load"
+ EVENT_DATA := <dm_version_str> ";" <device_metadata> ";" <table_load_data>
+
+ dm_version_str := "dm_version=" <N> "." <N> "." <N>
+                  Same as Device Mapper driver version.
+ device_metadata := <device_name> "," <device_uuid> "," <device_major> "," <device_minor> ","
+                   <minor_count> "," <num_device_targets> ";"
+
+ device_name := "name=" <dm-device-name>
+ device_uuid := "uuid=" <dm-device-uuid>
+ device_major := "major=" <N>
+ device_minor := "minor=" <N>
+ minor_count := "minor_count=" <N>
+ num_device_targets := "num_targets=" <N>
+ dm-device-name := Name of the device. If it contains special characters like '\', ',', ';',
+                   they are prefixed with '\'.
+ dm-device-uuid := UUID of the device. If it contains special characters like '\', ',', ';',
+                   they are prefixed with '\'.
+
+ table_load_data := <target_data>
+                    Represents the data (as name=value pairs) from various targets in the table,
+                    which is being loaded into the DM device's inactive table slot.
+ target_data := <target_data_row> | <target_data><target_data_row>
+
+ target_data_row := <target_index> "," <target_begin> "," <target_len> "," <target_name> ","
+                    <target_version> "," <target_attributes> ";"
+ target_index := "target_index=" <N>
+                 Represents nth target in the table (from 0 to N-1 targets specified in <num_device_targets>)
+                 If all the data for N targets doesn't fit in the given buffer - then the data that fits
+                 in the buffer (say from target 0 to x) is measured in a given IMA event.
+                 The remaining data from targets x+1 to N-1 is measured in the subsequent IMA events,
+                 with the same format as that of 'dm_table_load'
+                 i.e. <dm_version_str> ";" <device_metadata> ";" <table_load_data>.
+
+ target_begin := "target_begin=" <N>
+ target_len := "target_len=" <N>
+ target_name := Name of the target. 'linear', 'crypt', 'integrity' etc.
+                The targets that are supported for IMA measurements are documented below in the
+                'Supported targets' section.
+ target_version := "target_version=" <N> "." <N> "." <N>
+ target_attributes := Data containing comma separated list of name=value pairs of target specific attributes.
+
+ For instance, if a linear device is created with the following table entries,
+  # dmsetup create linear1
+  0 2 linear /dev/loop0 512
+  2 2 linear /dev/loop0 512
+  4 2 linear /dev/loop0 512
+  6 2 linear /dev/loop0 512
+
+ Then IMA ASCII measurement log will have the following entry:
+ (converted from ASCII to text for readability)
+
+ 10 a8c5ff755561c7a28146389d1514c318592af49a ima-buf sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72
+ dm_table_load
+ dm_version=4.45.0;
+ name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+ target_index=0,target_begin=0,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+ target_index=1,target_begin=2,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+ target_index=2,target_begin=4,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+ target_index=3,target_begin=6,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+
+2. Device resume:
+------------------
+When a suspended device is resumed, the device information and the hash of the
+data from previous load of an active table are measured.
+
+The IMA measurement log has the following format for 'dm_device_resume':
+
+::
+
+ EVENT_NAME := "dm_device_resume"
+ EVENT_DATA := <dm_version_str> ";" <device_metadata> ";" <active_table_hash> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_metadata := As described in the 'Table load' section above.
+ active_table_hash := "active_table_hash=" <table_hash_alg> ":" <table_hash>
+                      Rerpresents the hash of the IMA data being measured for the
+                      active table for the device.
+ table_hash_alg := Algorithm used to compute the hash.
+ table_hash := Hash of the (<dm_version_str> ";" <device_metadata> ";" <table_load_data> ";")
+               as described in the 'dm_table_load' above.
+               Note: If the table_load data spans across multiple IMA 'dm_table_load'
+               events for a given device, the hash is computed combining all the event data
+               i.e. (<dm_version_str> ";" <device_metadata> ";" <table_load_data> ";")
+               across all those events.
+ current_device_capacity := "current_device_capacity=" <N>
+
+ For instance, if a linear device is resumed with the following command,
+ #dmsetup resume linear1
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 56c00cc062ffc24ccd9ac2d67d194af3282b934e ima-buf sha256:e7d12c03b958b4e0e53e7363a06376be88d98a1ac191fdbd3baf5e4b77f329b6
+ dm_device_resume
+ dm_version=4.45.0;
+ name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+ active_table_hash=sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72;current_device_capacity=8;
+
+3. Device remove:
+------------------
+When a device is removed, the device information and a sha256 hash of the
+data from an active and inactive table are measured.
+
+The IMA measurement log has the following format for 'dm_device_remove':
+
+::
+
+ EVENT_NAME := "dm_device_remove"
+ EVENT_DATA := <dm_version_str> ";" <device_active_metadata> ";" <device_inactive_metadata> ";"
+               <active_table_hash> "," <inactive_table_hash> "," <remove_all> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_active_metadata := Device metadata that reflects the currently loaded active table.
+                           The format is same as 'device_metadata' described in the 'Table load' section above.
+ device_inactive_metadata := Device metadata that reflects the inactive table.
+                             The format is same as 'device_metadata' described in the 'Table load' section above.
+ active_table_hash := Hash of the currently loaded active table.
+                      The format is same as 'active_table_hash' described in the 'Device resume' section above.
+ inactive_table_hash :=  Hash of the inactive table.
+                         The format is same as 'active_table_hash' described in the 'Device resume' section above.
+ remove_all := "remove_all=" <yes_no>
+ yes_no := "y" | "n"
+ current_device_capacity := "current_device_capacity=" <N>
+
+ For instance, if a linear device is removed with the following command,
+  #dmsetup remove l1
+
+ then IMA ASCII measurement log will have the following entry:
+ (converted from ASCII to text for readability)
+
+ 10 790e830a3a7a31590824ac0642b3b31c2d0e8b38 ima-buf sha256:ab9f3c959367a8f5d4403d6ce9c3627dadfa8f9f0e7ec7899299782388de3840
+ dm_device_remove
+ dm_version=4.45.0;
+ device_active_metadata=name=l1,uuid=,major=253,minor=2,minor_count=1,num_targets=2;
+ device_inactive_metadata=name=l1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+ active_table_hash=sha256:4a7e62efaebfc86af755831998b7db6f59b60d23c9534fb16a4455907957953a,
+ inactive_table_hash=sha256:9d79c175bc2302d55a183e8f50ad4bafd60f7692fd6249e5fd213e2464384b86,remove_all=n;
+ current_device_capacity=2048;
+
+4. Table clear:
+----------------
+When an inactive table is cleared from the device, the device information and a sha256 hash of the
+data from an inactive table are measured.
+
+The IMA measurement log has the following format for 'dm_table_clear':
+
+::
+
+ EVENT_NAME := "dm_table_clear"
+ EVENT_DATA := <dm_version_str> ";" <device_inactive_metadata> ";" <inactive_table_hash> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_inactive_metadata := Device metadata that was captured during the load time inactive table being cleared.
+                             The format is same as 'device_metadata' described in the 'Table load' section above.
+ inactive_table_hash := Hash of the inactive table being cleared from the device.
+                        The format is same as 'active_table_hash' described in the 'Device resume' section above.
+ current_device_capacity := "current_device_capacity=" <N>
+
+ For instance, if a linear device's inactive table is cleared,
+  #dmsetup clear l1
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 77d347408f557f68f0041acb0072946bb2367fe5 ima-buf sha256:42f9ca22163fdfa548e6229dece2959bc5ce295c681644240035827ada0e1db5
+ dm_table_clear
+ dm_version=4.45.0;
+ name=l1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+ inactive_table_hash=sha256:75c0dc347063bf474d28a9907037eba060bfe39d8847fc0646d75e149045d545;current_device_capacity=1024;
+
+5. Device rename:
+------------------
+When an device's NAME or UUID is changed, the device information and the new NAME and UUID
+are measured.
+
+The IMA measurement log has the following format for 'dm_device_rename':
+
+::
+
+ EVENT_NAME := "dm_device_rename"
+ EVENT_DATA := <dm_version_str> ";" <device_active_metadata> ";" <new_device_name> "," <new_device_uuid> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_active_metadata := Device metadata that reflects the currently loaded active table.
+                           The format is same as 'device_metadata' described in the 'Table load' section above.
+ new_device_name := "new_name=" <dm-device-name>
+ dm-device-name := Same as <dm-device-name> described in 'Table load' section above
+ new_device_uuid := "new_uuid=" <dm-device-uuid>
+ dm-device-uuid := Same as <dm-device-uuid> described in 'Table load' section above
+ current_device_capacity := "current_device_capacity=" <N>
+
+ E.g 1: if a linear device's name is changed with the following command,
+  #dmsetup rename linear1 --setuuid 1234-5678
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 8b0423209b4c66ac1523f4c9848c9b51ee332f48 ima-buf sha256:6847b7258134189531db593e9230b257c84f04038b5a18fd2e1473860e0569ac
+ dm_device_rename
+ dm_version=4.45.0;
+ name=linear1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;new_name=linear1,new_uuid=1234-5678;
+ current_device_capacity=1024;
+
+ E.g 2:  if a linear device's name is changed with the following command,
+  # dmsetup rename linear1 linear=2
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 bef70476b99c2bdf7136fae033aa8627da1bf76f ima-buf sha256:8c6f9f53b9ef9dc8f92a2f2cca8910e622543d0f0d37d484870cb16b95111402
+ dm_device_rename
+ dm_version=4.45.0;
+ name=linear1,uuid=1234-5678,major=253,minor=2,minor_count=1,num_targets=1;
+ new_name=linear\=2,new_uuid=1234-5678;
+ current_device_capacity=1024;
+
+Supported targets:
+==================
+
+Following targets are supported to measure their data using IMA:
+
+ 1. cache
+ #. crypt
+ #. integrity
+ #. linear
+ #. mirror
+ #. multipath
+ #. raid
+ #. snapshot
+ #. striped
+ #. verity
+
+1. cache
+---------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'cache' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <metadata_mode> "," <cache_metadata_device> ","
+                      <cache_device> "," <cache_origin_device> "," <writethrough> "," <writeback> ","
+                      <passthrough> "," <no_discard_passdown> ";"
+
+ target_name := "target_name=cache"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ metadata_mode := "metadata_mode=" <cache_metadata_mode>
+ cache_metadata_mode := "fail" | "ro" | "rw"
+ cache_device := "cache_device=" <cache_device_name_string>
+ cache_origin_device := "cache_origin_device=" <cache_origin_device_string>
+ writethrough := "writethrough=" <yes_no>
+ writeback := "writeback=" <yes_no>
+ passthrough := "passthrough=" <yes_no>
+ no_discard_passdown := "no_discard_passdown=" <yes_no>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'cache' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'cache' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;name=cache1,uuid=cache_uuid,major=253,minor=2,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=28672,target_name=cache,target_version=2.2.0,metadata_mode=rw,
+ cache_metadata_device=253:4,cache_device=253:3,cache_origin_device=253:5,writethrough=y,writeback=n,
+ passthrough=n,metadata2=y,no_discard_passdown=n;
+
+
+2. crypt
+---------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'crypt' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <allow_discards> "," <same_cpu_crypt> ","
+                      <submit_from_crypt_cpus> "," <no_read_workqueue> "," <no_write_workqueue> ","
+                      <iv_large_sectors> "," <iv_large_sectors> "," [<integrity_tag_size> ","] [<cipher_auth> ","]
+                      [<sector_size> ","] [<cipher_string> ","] <key_size> "," <key_parts> ","
+                      <key_extra_size> "," <key_mac_size> ";"
+
+ target_name := "target_name=crypt"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ allow_discards := "allow_discards=" <yes_no>
+ same_cpu_crypt := "same_cpu_crypt=" <yes_no>
+ submit_from_crypt_cpus := "submit_from_crypt_cpus=" <yes_no>
+ no_read_workqueue := "no_read_workqueue=" <yes_no>
+ no_write_workqueue := "no_write_workqueue=" <yes_no>
+ iv_large_sectors := "iv_large_sectors=" <yes_no>
+ integrity_tag_size := "integrity_tag_size=" <N>
+ cipher_auth := "cipher_auth=" <string>
+ sector_size := "sector_size="  <N>
+ cipher_string := "cipher_string="
+ key_size := "key_size="  <N>
+ key_parts := "key_parts="  <N>
+ key_extra_size := "key_extra_size="  <N>
+ key_mac_size := "key_mac_size="  <N>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'crypt' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'crypt' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=crypt1,uuid=crypt_uuid1,major=253,minor=0,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=1953125,target_name=crypt,target_version=1.23.0,
+ allow_discards=y,same_cpu=n,submit_from_crypt_cpus=n,no_read_workqueue=n,no_write_workqueue=n,
+ iv_large_sectors=n,cipher_string=aes-xts-plain64,key_size=32,key_parts=1,key_extra_size=0,key_mac_size=0;
+
+3. integrity
+-------------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'integrity' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <dev_name> "," <start>
+                      <tag_size> "," <mode> "," [<meta_device> ","] [<block_size> ","] <recalculate> ","
+                      <allow_discards> "," <allow_discards_keyed> "," <fix_padding> "," <fix_hmac> ","
+                      <legacy_recalculate> ","
+                      <journal_sectors> "," <interleave_sectors> "," <buffer_sectors> ";"
+
+ target_name := "target_name=integrity"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ dev_name := "dev_name=" <device_name_str>
+ start := "start=" <N>
+ tag_size := "tag_size=" <N>
+ mode := "mode=" <integrity_mode_str>
+ integrity_mode_str := "J" | "B" | "D" | "R"
+ meta_device := "meta_device=" <meta_device_str>
+ block_size := "block_size=" <N>
+ recalculate := "recalculate=" <yes_no>
+ allow_discards := "allow_discards=" <yes_no>
+ allow_discards_keyed := "allow_discards_keyed=" <yes_no>
+ fix_padding := "fix_padding=" <yes_no>
+ fix_hmac := "fix_hmac=" <yes_no>
+ legacy_recalculate := "legacy_recalculate=" <yes_no>
+ journal_sectors := "journal_sectors=" <N>
+ interleave_sectors := "interleave_sectors=" <N>
+ buffer_sectors := "buffer_sectors=" <N>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'integrity' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'integrity' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=integrity1,uuid=,major=253,minor=1,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=7856,target_name=integrity,target_version=1.10.0,
+ dev_name=253:0,start=0,tag_size=32,mode=J,recalculate=n,allow_discards=n,
+ allow_discards_keyed=n,fix_padding=n,
+ fix_hmac=n,legacy_recalculate=n,journal_sectors=88,interleave_sectors=32768,buffer_sectors=128;
+
+
+4. linear
+----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'linear' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <device_name> <,> <start> ";"
+
+ target_name := "target_name=linear"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ device_name := "device_name=" <linear_device_name_str>
+ start := "start=" <N>
+
+ E.g.
+ When a 'linear' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'linear' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=linear1,uuid=linear_uuid1,major=253,minor=2,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=28672,target_name=linear,target_version=1.4.0,
+ device_name=253:1,start=2048;
+
+5. mirror
+----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'mirror' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <nr_mirrors> ","
+                      <mirror_device_data> "," <handle_errors> "," <keep_log> "," <log_type_status> ";"
+
+ target_name := "target_name=mirror"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ nr_mirrors := "nr_mirrors=" <NR>
+ mirror_device_data := <mirror_device_row> | <mirror_device_data><mirror_device_row>
+                       mirror_device_row is repeated <NR> times - for <NR> described in <nr_mirrors>.
+ mirror_device_row := <mirror_device_name> "," <mirror_device_status>
+ mirror_device_name := "mirror_device_" <X> "=" <mirror_device_name_str>
+                       where <X> ranges from 0 to (<NR> -1) - for <NR> described in <nr_mirrors>.
+ mirror_device_status := "mirror_device_" <X> "_status=" <mirror_device_status_char>
+                         where <X> ranges from 0 to (<NR> -1) - for <NR> described in <nr_mirrors>.
+ mirror_device_status_char := "A" | "F" | "D" | "S" | "R" | "U"
+ handle_errors := "handle_errors=" <yes_no>
+ keep_log := "keep_log=" <yes_no>
+ log_type_status := "log_type_status=" <log_type_status_str>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'mirror' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'mirror' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=mirror1,uuid=mirror_uuid1,major=253,minor=6,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=2048,target_name=mirror,target_version=1.14.0,nr_mirrors=2,
+    mirror_device_0=253:4,mirror_device_0_status=A,
+    mirror_device_1=253:5,mirror_device_1_status=A,
+ handle_errors=y,keep_log=n,log_type_status=;
+
+6. multipath
+-------------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'multipath' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <nr_priority_groups>
+                      ["," <pg_state> "," <priority_groups> "," <priority_group_paths>] ";"
+
+ target_name := "target_name=multipath"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ nr_priority_groups := "nr_priority_groups=" <NPG>
+ priority_groups := <priority_groups_row>|<priority_groups_row><priority_groups>
+ priority_groups_row := "pg_state_" <X> "=" <pg_state_str> "," "nr_pgpaths_" <X>  "=" <NPGP> ","
+                        "path_selector_name_" <X> "=" <string> "," <priority_group_paths>
+                        where <X> ranges from 0 to (<NPG> -1) - for <NPG> described in <nr_priority_groups>.
+ pg_state_str := "E" | "A" | "D"
+ <priority_group_paths> := <priority_group_paths_row> | <priority_group_paths_row><priority_group_paths>
+ priority_group_paths_row := "path_name_" <X> "_" <Y> "=" <string> "," "is_active_" <X> "_" <Y> "=" <is_active_str>
+                             "fail_count_" <X> "_" <Y> "=" <N> "," "path_selector_status_" <X> "_" <Y> "=" <path_selector_status_str>
+                             where <X> ranges from 0 to (<NPG> -1) - for <NPG> described in <nr_priority_groups>,
+                             and <Y> ranges from 0 to (<NPGP> -1) - for <NPGP> described in <priority_groups_row>.
+ is_active_str := "A" | "F"
+
+ E.g.
+ When a 'multipath' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'multipath' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=mp,uuid=,major=253,minor=0,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=2097152,target_name=multipath,target_version=1.14.0,nr_priority_groups=2,
+    pg_state_0=E,nr_pgpaths_0=2,path_selector_name_0=queue-length,
+        path_name_0_0=8:16,is_active_0_0=A,fail_count_0_0=0,path_selector_status_0_0=,
+        path_name_0_1=8:32,is_active_0_1=A,fail_count_0_1=0,path_selector_status_0_1=,
+    pg_state_1=E,nr_pgpaths_1=2,path_selector_name_1=queue-length,
+        path_name_1_0=8:48,is_active_1_0=A,fail_count_1_0=0,path_selector_status_1_0=,
+        path_name_1_1=8:64,is_active_1_1=A,fail_count_1_1=0,path_selector_status_1_1=;
+
+7. raid
+--------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'raid' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <raid_type> "," <raid_disks> "," <raid_state>
+                      <raid_device_status> ["," journal_dev_mode] ";"
+
+ target_name := "target_name=raid"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ raid_type := "raid_type=" <raid_type_str>
+ raid_disks := "raid_disks=" <NRD>
+ raid_state := "raid_state=" <raid_state_str>
+ raid_state_str := "frozen" | "reshape" |"resync" | "check" | "repair" | "recover" | "idle" |"undef"
+ raid_device_status := <raid_device_status_row> | <raid_device_status_row><raid_device_status>
+                       <raid_device_status_row> is repeated <NRD> times - for <NRD> described in <raid_disks>.
+ raid_device_status_row := "raid_device_" <X> "_status=" <raid_device_status_str>
+                           where <X> ranges from 0 to (<NRD> -1) - for <NRD> described in <raid_disks>.
+ raid_device_status_str := "A" | "D" | "a" | "-"
+ journal_dev_mode := "journal_dev_mode=" <journal_dev_mode_str>
+ journal_dev_mode_str := "writethrough" | "writeback" | "invalid"
+
+ E.g.
+ When a 'raid' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'raid' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=raid_LV1,uuid=uuid_raid_LV1,major=253,minor=12,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=2048,target_name=raid,target_version=1.15.1,
+ raid_type=raid10,raid_disks=4,raid_state=idle,
+    raid_device_0_status=A,
+    raid_device_1_status=A,
+    raid_device_2_status=A,
+    raid_device_3_status=A;
+
+
+8. snapshot
+------------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'snapshot' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <snap_origin_name> ","
+                      <snap_cow_name> "," <snap_valid> "," <snap_merge_failed> "," <snapshot_overflowed> ";"
+
+ target_name := "target_name=snapshot"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ snap_origin_name := "snap_origin_name=" <string>
+ snap_cow_name := "snap_cow_name=" <string>
+ snap_valid := "snap_valid=" <yes_no>
+ snap_merge_failed := "snap_merge_failed=" <yes_no>
+ snapshot_overflowed := "snapshot_overflowed=" <yes_no>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'snapshot' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'snapshot' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=snap1,uuid=snap_uuid1,major=253,minor=13,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=4096,target_name=snapshot,target_version=1.16.0,
+ snap_origin_name=253:11,snap_cow_name=253:12,snap_valid=y,snap_merge_failed=n,snapshot_overflowed=n;
+
+9. striped
+-----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'striped' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <stripes> "," <chunk_size> ","
+                      <stripe_data> ";"
+
+ target_name := "target_name=striped"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ stripes := "stripes=" <NS>
+ chunk_size := "chunk_size=" <N>
+ stripe_data := <stripe_data_row>|<stripe_data><stripe_data_row>
+ stripe_data_row := <stripe_device_name> "," <stripe_physical_start> "," <stripe_status>
+ stripe_device_name := "stripe_" <X> "_device_name=" <stripe_device_name_str>
+                       where <X> ranges from 0 to (<NS> -1) - for <NS> described in <stripes>.
+ stripe_physical_start := "stripe_" <X> "_physical_start=" <N>
+                           where <X> ranges from 0 to (<NS> -1) - for <NS> described in <stripes>.
+ stripe_status := "stripe_" <X> "_status=" <stripe_status_str>
+                  where <X> ranges from 0 to (<NS> -1) - for <NS> described in <stripes>.
+ stripe_status_str := "D" | "A"
+
+ E.g.
+ When a 'striped' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'striped' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=striped1,uuid=striped_uuid1,major=253,minor=5,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=640,target_name=striped,target_version=1.6.0,stripes=2,chunk_size=64,
+    stripe_0_device_name=253:0,stripe_0_physical_start=2048,stripe_0_status=A,
+    stripe_1_device_name=253:3,stripe_1_physical_start=2048,stripe_1_status=A;
+
+10. verity
+----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'verity' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <hash_failed> "," <verity_version> ","
+                      <data_device_name> "," <hash_device_name> "," <verity_algorithm> "," <root_digest> ","
+                      <salt> "," <ignore_zero_blocks> "," <check_at_most_once> ["," <root_hash_sig_key_desc>]
+                      ["," <verity_mode>] ";"
+
+ target_name := "target_name=verity"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ hash_failed := "hash_failed=" <hash_failed_str>
+ hash_failed_str := "C" | "V"
+ verity_version := "verity_version=" <verity_version_str>
+ data_device_name := "data_device_name=" <data_device_name_str>
+ hash_device_name := "hash_device_name=" <hash_device_name_str>
+ verity_algorithm := "verity_algorithm=" <verity_algorithm_str>
+ root_digest := "root_digest=" <root_digest_str>
+ salt := "salt=" <salt_str>
+ salt_str := "-" <verity_salt_str>
+ ignore_zero_blocks := "ignore_zero_blocks=" <yes_no>
+ check_at_most_once := "check_at_most_once=" <yes_no>
+ root_hash_sig_key_desc := "root_hash_sig_key_desc="
+ verity_mode := "verity_mode=" <verity_mode_str>
+ verity_mode_str := "ignore_corruption" | "restart_on_corruption" | "panic_on_corruption" | "invalid"
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'verity' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'verity' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=test-verity,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=1953120,target_name=verity,target_version=1.8.0,hash_failed=V,
+ verity_version=1,data_device_name=253:1,hash_device_name=253:0,verity_algorithm=sha256,
+ root_digest=29cb87e60ce7b12b443ba6008266f3e41e93e403d7f298f8e3f316b29ff89c5e,
+ salt=e48da609055204e89ae53b655ca2216dd983cf3cb829f34f63a297d106d53e2d,
+ ignore_zero_blocks=n,check_at_most_once=n;
diff --git a/Documentation/admin-guide/device-mapper/dm-init.rst b/Documentation/admin-guide/device-mapper/dm-init.rst
new file mode 100644
index 000000000..981d6a907
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-init.rst
@@ -0,0 +1,133 @@
+================================
+Early creation of mapped devices
+================================
+
+It is possible to configure a device-mapper device to act as the root device for
+your system in two ways.
+
+The first is to build an initial ramdisk which boots to a minimal userspace
+which configures the device, then pivot_root(8) in to it.
+
+The second is to create one or more device-mappers using the module parameter
+"dm-mod.create=" through the kernel boot command line argument.
+
+The format is specified as a string of data separated by commas and optionally
+semi-colons, where:
+
+ - a comma is used to separate fields like name, uuid, flags and table
+   (specifies one device)
+ - a semi-colon is used to separate devices.
+
+So the format will look like this::
+
+ dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+]
+
+Where::
+
+	<name>		::= The device name.
+	<uuid>		::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | ""
+	<minor>		::= The device minor number | ""
+	<flags>		::= "ro" | "rw"
+	<table>		::= <start_sector> <num_sectors> <target_type> <target_args>
+	<target_type>	::= "verity" | "linear" | ... (see list below)
+
+The dm line should be equivalent to the one used by the dmsetup tool with the
+`--concise` argument.
+
+Target types
+============
+
+Not all target types are available as there are serious risks in allowing
+activation of certain DM targets without first using userspace tools to check
+the validity of associated metadata.
+
+======================= =======================================================
+`cache`			constrained, userspace should verify cache device
+`crypt`			allowed
+`delay`			allowed
+`era`			constrained, userspace should verify metadata device
+`flakey`		constrained, meant for test
+`linear`		allowed
+`log-writes`		constrained, userspace should verify metadata device
+`mirror`		constrained, userspace should verify main/mirror device
+`raid`			constrained, userspace should verify metadata device
+`snapshot`		constrained, userspace should verify src/dst device
+`snapshot-origin`	allowed
+`snapshot-merge`	constrained, userspace should verify src/dst device
+`striped`		allowed
+`switch`		constrained, userspace should verify dev path
+`thin`			constrained, requires dm target message from userspace
+`thin-pool`		constrained, requires dm target message from userspace
+`verity`		allowed
+`writecache`		constrained, userspace should verify cache device
+`zero`			constrained, not meant for rootfs
+======================= =======================================================
+
+If the target is not listed above, it is constrained by default (not tested).
+
+Examples
+========
+An example of booting to a linear array made up of user-mode linux block
+devices::
+
+  dm-mod.create="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0
+
+This will boot to a rw dm-linear target of 8192 sectors split across two block
+devices identified by their major:minor numbers.  After boot, udev will rename
+this target to /dev/mapper/lroot (depending on the rules). No uuid was assigned.
+
+An example of multiple device-mappers, with the dm-mod.create="..." contents
+is shown here split on multiple lines for readability::
+
+  dm-linear,,1,rw,
+    0 32768 linear 8:1 0,
+    32768 1024000 linear 8:2 0;
+  dm-verity,,3,ro,
+    0 1638400 verity 1 /dev/sdc1 /dev/sdc2 4096 4096 204800 1 sha256
+    ac87db56303c9c1da433d7209b5a6ef3e4779df141200cbd7c157dcb8dd89c42
+    5ebfe87f7df3235b80a117ebc4078e44f55045487ad4a96581d1adb564615b51
+
+Other examples (per target):
+
+"crypt"::
+
+  dm-crypt,,8,ro,
+    0 1048576 crypt aes-xts-plain64
+    babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0
+    /dev/sda 0 1 allow_discards
+
+"delay"::
+
+  dm-delay,,4,ro,0 409600 delay /dev/sda1 0 500
+
+"linear"::
+
+  dm-linear,,,rw,
+    0 32768 linear /dev/sda1 0,
+    32768 1024000 linear /dev/sda2 0,
+    1056768 204800 linear /dev/sda3 0,
+    1261568 512000 linear /dev/sda4 0
+
+"snapshot-origin"::
+
+  dm-snap-orig,,4,ro,0 409600 snapshot-origin 8:2
+
+"striped"::
+
+  dm-striped,,4,ro,0 1638400 striped 4 4096
+  /dev/sda1 0 /dev/sda2 0 /dev/sda3 0 /dev/sda4 0
+
+"verity"::
+
+  dm-verity,,4,ro,
+    0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256
+    fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd
+    51934789604d1b92399c52e7cb149d1b3a1b74bbbcb103b2a0aaacbed5c08584
+
+For setups using device-mapper on top of asynchronously probed block
+devices (MMC, USB, ..), it may be necessary to tell dm-init to
+explicitly wait for them to become available before setting up the
+device-mapper tables. This can be done with the "dm-mod.waitfor="
+module parameter, which takes a list of devices to wait for::
+
+  dm-mod.waitfor=<device1>[,..,<deviceN>]
diff --git a/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst b/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst
new file mode 100644
index 000000000..8258a72f0
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst
@@ -0,0 +1,129 @@
+==============
+dm-inlinecrypt
+==============
+
+Device-Mapper's "inlinecrypt" target provides transparent encryption of block devices
+using the inline encryption hardware.
+
+For a more detailed description of inline encryption, see:
+https://docs.kernel.org/block/inline-encryption.html
+
+Parameters::
+
+	      <cipher> <key> <iv_offset> <device path> \
+	      <offset> [<#opt_params> <opt_params>]
+
+<cipher>
+    Encryption cipher type.
+
+    The cipher specifications format is::
+
+       cipher
+
+    Examples::
+
+       aes-xts-plain64
+
+    The cipher type corresponds to the encryption modes supported by
+    inline crypto in the block layer. Currently, only
+    BLK_ENCRYPTION_MODE_AES_256_XTS (i.e. aes-xts-plain64) is supported.
+
+<key>
+    Key used for encryption. It is encoded either as a hexadecimal number
+    or it can be passed as <key_string> prefixed with single colon
+    character (':') for keys residing in kernel keyring service.
+    You can only use key sizes that are valid for the selected cipher.
+    Note that the size in bytes of a valid key must be in below range.
+
+        [BLK_CRYPTO_KEY_TYPE_RAW, BLK_CRYPTO_KEY_TYPE_HW_WRAPPED]
+
+<key_string>
+    The kernel keyring key is identified by string in following format:
+    <key_size>:<keyring_type>:<key_description>.
+
+<key_size>
+    The encryption key size in bytes. The kernel key payload size must match
+    the value passed in <key_size>.
+
+<keyring_type>
+    The type of the key inside the kernel keyring. It can be either 'logon',
+    or 'trusted' kernel key type.
+
+<key_description>
+    The kernel keyring key description inlinecrypt target should look for
+    when loading key of <keyring_type>.
+
+<iv_offset>
+    The IV offset is a sector count that is added to the sector number
+    before creating the IV.
+
+<device path>
+    This is the device that is going to be used as backend and contains the
+    encrypted data.  You can specify it as a path like /dev/xxx or a device
+    number <major>:<minor>.
+
+<offset>
+    Starting sector within the device where the encrypted data begins.
+
+<#opt_params>
+    Number of optional parameters. If there are no optional parameters,
+    the optional parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        keytype:raw allow_discards sector_size:4096 iv_large_sectors
+
+<key_type>
+    The type of the key as seen by the block layer, either standard or
+    hardware-wrapped. The string is supplied in the table as <keytype:raw>
+    or <keytype:hw-wrapped>.
+
+allow_discards
+    Block discard requests (a.k.a. TRIM) are passed through the inlinecrypt
+    device. The default is to ignore discard requests.
+
+    WARNING: Assess the specific security risks carefully before enabling this
+    option.  For example, allowing discards on encrypted devices may lead to
+    the leak of information about the ciphertext device (filesystem type,
+    used space etc.) if the discarded blocks can be located easily on the
+    device later.
+
+sector_size:<bytes>
+    Use <bytes> as the encryption unit instead of 512 bytes sectors.
+    This option can be in range 512 - 4096 bytes and must be power of two.
+    Virtual device will announce this size as a minimal IO and logical sector.
+
+iv_large_sectors
+    Use <sector_size>-based sector numbers for IV generation instead of
+    512-byte sectors.
+
+    For dm-inlinecrypt, this flag must be specified when <sector_size>
+    is larger than 512 bytes. The legacy 512-byte-based IV behavior is
+    not supported.
+
+    When specified, if <sector_size> is 4096 bytes, plain64 IV for the
+    second sector will be 1, and <iv_offset> must be a multiple of
+    <sector_size> (in 512-byte units).
+
+Example scripts
+===============
+Currently, dm-inlinecrypt devices must be set up directly using dmsetup.
+There is no userspace support yet to integrate dm-inlinecrypt with LUKS
+or cryptsetup. In particular, cryptsetup currently only supports
+dm-crypt, and cannot be used to create dm-inlinecrypt mappings.
+
+The following examples demonstrate how to create dm-inlinecrypt devices
+using dmsetup
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using dmsetup
+	dmsetup create inlinecrypt1 --table "0 `blockdev --getsz $1` inlinecrypt aes-xts-plain64 babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0 0 $1 0 1 keytype:raw"
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using dmsetup when encryption key is stored in keyring service
+	dmsetup create inlinecrypt2 --table "0 `blockdev --getsz $1` inlinecrypt aes-xts-plain64 :64:logon:fde:dminlinecrypt_test_key 0 0 $1 0 1 keytype:raw"
+
diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst
new file mode 100644
index 000000000..9c2130142
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst
@@ -0,0 +1,321 @@
+============
+dm-integrity
+============
+
+The dm-integrity target emulates a block device that has additional
+per-sector tags that can be used for storing integrity information.
+
+A general problem with storing integrity tags with every sector is that
+writing the sector and the integrity tag must be atomic - i.e. in case of
+crash, either both sector and integrity tag or none of them is written.
+
+To guarantee write atomicity, the dm-integrity target uses journal, it
+writes sector data and integrity tags into a journal, commits the journal
+and then copies the data and integrity tags to their respective location.
+
+The dm-integrity target can be used with the dm-crypt target - in this
+situation the dm-crypt target creates the integrity data and passes them
+to the dm-integrity target via bio_integrity_payload attached to the bio.
+In this mode, the dm-crypt and dm-integrity targets provide authenticated
+disk encryption - if the attacker modifies the encrypted device, an I/O
+error is returned instead of random data.
+
+The dm-integrity target can also be used as a standalone target, in this
+mode it calculates and verifies the integrity tag internally. In this
+mode, the dm-integrity target can be used to detect silent data
+corruption on the disk or in the I/O path.
+
+There's an alternate mode of operation where dm-integrity uses a bitmap
+instead of a journal. If a bit in the bitmap is 1, the corresponding
+region's data and integrity tags are not synchronized - if the machine
+crashes, the unsynchronized regions will be recalculated. The bitmap mode
+is faster than the journal mode, because we don't have to write the data
+twice, but it is also less reliable, because if data corruption happens
+when the machine crashes, it may not be detected.
+
+When loading the target for the first time, the kernel driver will format
+the device. But it will only format the device if the superblock contains
+zeroes. If the superblock is neither valid nor zeroed, the dm-integrity
+target can't be loaded.
+
+Accesses to the on-disk metadata area containing checksums (aka tags) are
+buffered using dm-bufio. When an access to any given metadata area
+occurs, each unique metadata area gets its own buffer(s). The buffer size
+is capped at the size of the metadata area, but may be smaller, thereby
+requiring multiple buffers to represent the full metadata area. A smaller
+buffer size will produce a smaller resulting read/write operation to the
+metadata area for small reads/writes. The metadata is still read even in
+a full write to the data covered by a single buffer.
+
+To use the target for the first time:
+
+1. overwrite the superblock with zeroes
+2. load the dm-integrity target with one-sector size, the kernel driver
+   will format the device
+3. unload the dm-integrity target
+4. read the "provided_data_sectors" value from the superblock
+5. load the dm-integrity target with the target size
+   "provided_data_sectors"
+6. if you want to use dm-integrity with dm-crypt, load the dm-crypt target
+   with the size "provided_data_sectors"
+
+
+Target arguments:
+
+1. the underlying block device
+
+2. the number of reserved sector at the beginning of the device - the
+   dm-integrity won't read of write these sectors
+
+3. the size of the integrity tag (if "-" is used, the size is taken from
+   the internal-hash algorithm)
+
+4. mode:
+
+	D - direct writes (without journal)
+		in this mode, journaling is
+		not used and data sectors and integrity tags are written
+		separately. In case of crash, it is possible that the data
+		and integrity tag doesn't match.
+	J - journaled writes
+		data and integrity tags are written to the
+		journal and atomicity is guaranteed. In case of crash,
+		either both data and tag or none of them are written. The
+		journaled mode degrades write throughput twice because the
+		data have to be written twice.
+	B - bitmap mode - data and metadata are written without any
+		synchronization, the driver maintains a bitmap of dirty
+		regions where data and metadata don't match. This mode can
+		only be used with internal hash.
+	R - recovery mode - in this mode, journal is not replayed,
+		checksums are not checked and writes to the device are not
+		allowed. This mode is useful for data recovery if the
+		device cannot be activated in any of the other standard
+		modes.
+	I - inline mode - in this mode, dm-integrity will store integrity
+		data directly in the underlying device sectors.
+		The underlying device must have an integrity profile that
+		allows storing user integrity data and provides enough
+		space for the selected integrity tag.
+
+5. the number of additional arguments
+
+Additional arguments:
+
+journal_sectors:number
+	The size of journal, this argument is used only if formatting the
+	device. If the device is already formatted, the value from the
+	superblock is used.
+
+interleave_sectors:number (default 32768)
+	The number of interleaved sectors. This values is rounded down to
+	a power of two. If the device is already formatted, the value from
+	the superblock is used.
+
+meta_device:device
+	Don't interleave the data and metadata on the device. Use a
+	separate device for metadata.
+
+buffer_sectors:number (default 128)
+	The number of sectors in one metadata buffer. The value is rounded
+	down to a power of two.
+
+journal_watermark:number (default 50)
+	The journal watermark in percents. When the size of the journal
+	exceeds this watermark, the thread that flushes the journal will
+	be started.
+
+commit_time:number (default 10000)
+	Commit time in milliseconds. When this time passes, the journal is
+	written. The journal is also written immediately if the FLUSH
+	request is received.
+
+internal_hash:algorithm(:key)	(the key is optional)
+	Use internal hash or crc.
+	When this argument is used, the dm-integrity target won't accept
+	integrity tags from the upper target, but it will automatically
+	generate and verify the integrity tags.
+
+	You can use a crc algorithm (such as crc32), then integrity target
+	will protect the data against accidental corruption.
+	You can also use a hmac algorithm (for example
+	"hmac(sha256):0123456789abcdef"), in this mode it will provide
+	cryptographic authentication of the data without encryption.
+
+	When this argument is not used, the integrity tags are accepted
+	from an upper layer target, such as dm-crypt. The upper layer
+	target should check the validity of the integrity tags.
+
+recalculate
+	Recalculate the integrity tags automatically. It is only valid
+	when using internal hash.
+
+journal_crypt:algorithm(:key)	(the key is optional)
+	Encrypt the journal using given algorithm to make sure that the
+	attacker can't read the journal. You can use a block cipher here
+	(such as "cbc(aes)") or a stream cipher (for example "chacha20"
+	or "ctr(aes)").
+
+	The journal contains history of last writes to the block device,
+	an attacker reading the journal could see the last sector numbers
+	that were written. From the sector numbers, the attacker can infer
+	the size of files that were written. To protect against this
+	situation, you can encrypt the journal.
+
+journal_mac:algorithm(:key)	(the key is optional)
+	Protect sector numbers in the journal from accidental or malicious
+	modification. To protect against accidental modification, use a
+	crc algorithm, to protect against malicious modification, use a
+	hmac algorithm with a key.
+
+	This option is not needed when using internal-hash because in this
+	mode, the integrity of journal entries is checked when replaying
+	the journal. Thus, modified sector number would be detected at
+	this stage.
+
+block_size:number (default 512)
+	The size of a data block in bytes. The larger the block size the
+	less overhead there is for per-block integrity metadata.
+	Supported values are 512, 1024, 2048 and 4096 bytes.
+
+sectors_per_bit:number
+	In the bitmap mode, this parameter specifies the number of
+	512-byte sectors that corresponds to one bitmap bit.
+
+bitmap_flush_interval:number
+	The bitmap flush interval in milliseconds. The metadata buffers
+	are synchronized when this interval expires.
+
+allow_discards
+	Allow block discard requests (a.k.a. TRIM) for the integrity device.
+	Discards are only allowed to devices using internal hash.
+
+	A discarded block is marked with a constant filler tag that anyone
+	with raw write access to the backing device can forge without the
+	key. Use allow_discards_keyed instead on new volumes.
+
+allow_discards_keyed
+	Like allow_discards, but marks a discarded block with a keyed
+	checksum of the sector number, HMAC_key(salt || sector), instead of
+	the constant filler tag, so it can't be forged without the
+	integrity key.
+
+	Not compatible with volumes that already have discarded blocks
+	marked the old way; only use on a freshly formatted volume.
+
+fix_padding
+	Use a smaller padding of the tag area that is more
+	space-efficient. If this option is not present, large padding is
+	used - that is for compatibility with older kernels.
+
+fix_hmac
+	Improve security of internal_hash and journal_mac:
+
+	- the section number is mixed to the mac, so that an attacker can't
+	  copy sectors from one journal section to another journal section
+	- the superblock is protected by journal_mac
+	- a 16-byte salt stored in the superblock is mixed to the mac, so
+	  that the attacker can't detect that two disks have the same hmac
+	  key and also to disallow the attacker to move sectors from one
+	  disk to another
+
+legacy_recalculate
+	Allow recalculating of volumes with HMAC keys. This is disabled by
+	default for security reasons - an attacker could modify the volume,
+	set recalc_sector to zero, and the kernel would not detect the
+	modification.
+
+The journal mode (D/J), buffer_sectors, journal_watermark, commit_time and
+allow_discards can be changed when reloading the target (load an inactive
+table and swap the tables with suspend and resume). The other arguments
+should not be changed when reloading the target because the layout of disk
+data depend on them and the reloaded target would be non-functional.
+
+For example, on a device using the default interleave_sectors of 32768, a
+block_size of 512, and an internal_hash of crc32c with a tag size of 4
+bytes, it will take 128 KiB of tags to track a full data area, requiring
+256 sectors of metadata per data area. With the default buffer_sectors of
+128, that means there will be 2 buffers per metadata area, or 2 buffers
+per 16 MiB of data.
+
+Status line:
+
+1. the number of integrity mismatches
+2. provided data sectors - that is the number of sectors that the user
+   could use
+3. the current recalculating position (or '-' if we didn't recalculate)
+
+
+The layout of the formatted block device:
+
+* reserved sectors
+    (they are not used by this target, they can be used for
+    storing LUKS metadata or for other purpose), the size of the reserved
+    area is specified in the target arguments
+
+* superblock (4kiB)
+	* magic string - identifies that the device was formatted
+	* version
+	* log2(interleave sectors)
+	* integrity tag size
+	* the number of journal sections
+	* provided data sectors - the number of sectors that this target
+	  provides (i.e. the size of the device minus the size of all
+	  metadata and padding). The user of this target should not send
+	  bios that access data beyond the "provided data sectors" limit.
+	* flags
+	    SB_FLAG_HAVE_JOURNAL_MAC
+		- a flag is set if journal_mac is used
+	    SB_FLAG_RECALCULATING
+		- recalculating is in progress
+	    SB_FLAG_DIRTY_BITMAP
+		- journal area contains the bitmap of dirty
+		  blocks
+	* log2(sectors per block)
+	* a position where recalculating finished
+* journal
+	The journal is divided into sections, each section contains:
+
+	* metadata area (4kiB), it contains journal entries
+
+	  - every journal entry contains:
+
+		* logical sector (specifies where the data and tag should
+		  be written)
+		* last 8 bytes of data
+		* integrity tag (the size is specified in the superblock)
+
+	  - every metadata sector ends with
+
+		* mac (8-bytes), all the macs in 8 metadata sectors form a
+		  64-byte value. It is used to store hmac of sector
+		  numbers in the journal section, to protect against a
+		  possibility that the attacker tampers with sector
+		  numbers in the journal.
+		* commit id
+
+	* data area (the size is variable; it depends on how many journal
+	  entries fit into the metadata area)
+
+	    - every sector in the data area contains:
+
+		* data (504 bytes of data, the last 8 bytes are stored in
+		  the journal entry)
+		* commit id
+
+	To test if the whole journal section was written correctly, every
+	512-byte sector of the journal ends with 8-byte commit id. If the
+	commit id matches on all sectors in a journal section, then it is
+	assumed that the section was written correctly. If the commit id
+	doesn't match, the section was written partially and it should not
+	be replayed.
+
+* one or more runs of interleaved tags and data.
+    Each run contains:
+
+	* tag area - it contains integrity tags. There is one tag for each
+	  sector in the data area. The size of this area is always 4KiB or
+	  greater.
+	* data area - it contains data sectors. The number of data sectors
+	  in one run must be a power of two. log2 of this value is stored
+	  in the superblock.
diff --git a/Documentation/admin-guide/device-mapper/dm-io.rst b/Documentation/admin-guide/device-mapper/dm-io.rst
new file mode 100644
index 000000000..d2492917a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-io.rst
@@ -0,0 +1,75 @@
+=====
+dm-io
+=====
+
+Dm-io provides synchronous and asynchronous I/O services. There are three
+types of I/O services available, and each type has a sync and an async
+version.
+
+The user must set up an io_region structure to describe the desired location
+of the I/O. Each io_region indicates a block-device along with the starting
+sector and size of the region::
+
+   struct io_region {
+      struct block_device *bdev;
+      sector_t sector;
+      sector_t count;
+   };
+
+Dm-io can read from one io_region or write to one or more io_regions. Writes
+to multiple regions are specified by an array of io_region structures.
+
+The first I/O service type takes a list of memory pages as the data buffer for
+the I/O, along with an offset into the first page::
+
+   struct page_list {
+      struct page_list *next;
+      struct page *page;
+   };
+
+   int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
+                  struct page_list *pl, unsigned int offset,
+                  unsigned long *error_bits);
+   int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
+                   struct page_list *pl, unsigned int offset,
+                   io_notify_fn fn, void *context);
+
+The second I/O service type takes an array of bio vectors as the data buffer
+for the I/O. This service can be handy if the caller has a pre-assembled bio,
+but wants to direct different portions of the bio to different devices::
+
+   int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where,
+                       int rw, struct bio_vec *bvec,
+                       unsigned long *error_bits);
+   int dm_io_async_bvec(unsigned int num_regions, struct io_region *where,
+                        int rw, struct bio_vec *bvec,
+                        io_notify_fn fn, void *context);
+
+The third I/O service type takes a pointer to a vmalloc'd memory buffer as the
+data buffer for the I/O. This service can be handy if the caller needs to do
+I/O to a large region but doesn't want to allocate a large number of individual
+memory pages::
+
+   int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
+                     void *data, unsigned long *error_bits);
+   int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
+                      void *data, io_notify_fn fn, void *context);
+
+Callers of the asynchronous I/O services must include the name of a completion
+callback routine and a pointer to some context data for the I/O::
+
+   typedef void (*io_notify_fn)(unsigned long error, void *context);
+
+The "error" parameter in this callback, as well as the `*error` parameter in
+all of the synchronous versions, is a bitset (instead of a simple error value).
+In the case of an write-I/O to multiple regions, this bitset allows dm-io to
+indicate success or failure on each individual region.
+
+Before using any of the dm-io services, the user should call dm_io_get()
+and specify the number of pages they expect to perform I/O on concurrently.
+Dm-io will attempt to resize its mempool to make sure enough pages are
+always available in order to avoid unnecessary waiting while performing I/O.
+
+When the user is finished using the dm-io services, they should call
+dm_io_put() and specify the same number of pages that were given on the
+dm_io_get() call.
diff --git a/Documentation/admin-guide/device-mapper/dm-log.rst b/Documentation/admin-guide/device-mapper/dm-log.rst
new file mode 100644
index 000000000..ba4fce39b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-log.rst
@@ -0,0 +1,57 @@
+=====================
+Device-Mapper Logging
+=====================
+The device-mapper logging code is used by some of the device-mapper
+RAID targets to track regions of the disk that are not consistent.
+A region (or portion of the address space) of the disk may be
+inconsistent because a RAID stripe is currently being operated on or
+a machine died while the region was being altered.  In the case of
+mirrors, a region would be considered dirty/inconsistent while you
+are writing to it because the writes need to be replicated for all
+the legs of the mirror and may not reach the legs at the same time.
+Once all writes are complete, the region is considered clean again.
+
+There is a generic logging interface that the device-mapper RAID
+implementations use to perform logging operations (see
+dm_dirty_log_type in include/linux/dm-dirty-log.h).  Various different
+logging implementations are available and provide different
+capabilities.  The list includes:
+
+==============	==============================================================
+Type		Files
+==============	==============================================================
+disk		drivers/md/dm-log.c
+core		drivers/md/dm-log.c
+userspace	drivers/md/dm-log-userspace* include/linux/dm-log-userspace.h
+==============	==============================================================
+
+The "disk" log type
+-------------------
+This log implementation commits the log state to disk.  This way, the
+logging state survives reboots/crashes.
+
+The "core" log type
+-------------------
+This log implementation keeps the log state in memory.  The log state
+will not survive a reboot or crash, but there may be a small boost in
+performance.  This method can also be used if no storage device is
+available for storing log state.
+
+The "userspace" log type
+------------------------
+This log type simply provides a way to export the log API to userspace,
+so log implementations can be done there.  This is done by forwarding most
+logging requests to userspace, where a daemon receives and processes the
+request.
+
+The structure used for communication between kernel and userspace are
+located in include/linux/dm-log-userspace.h.  Due to the frequency,
+diversity, and 2-way communication nature of the exchanges between
+kernel and userspace, 'connector' is used as the interface for
+communication.
+
+There are currently two userspace log implementations that leverage this
+framework - "clustered-disk" and "clustered-core".  These implementations
+provide a cluster-coherent log for shared-storage.  Device-mapper mirroring
+can be used in a shared-storage environment when the cluster log implementations
+are employed.
diff --git a/Documentation/admin-guide/device-mapper/dm-pcache.rst b/Documentation/admin-guide/device-mapper/dm-pcache.rst
new file mode 100644
index 000000000..09d327ef4
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-pcache.rst
@@ -0,0 +1,202 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================================
+dm-pcache — Persistent Cache
+=================================
+
+*Author: Dongsheng Yang <dongsheng.yang@linux.dev>*
+
+This document describes *dm-pcache*, a Device-Mapper target that lets a
+byte-addressable *DAX* (persistent-memory, “pmem”) region act as a
+high-performance, crash-persistent cache in front of a slower block
+device.  The code lives in `drivers/md/dm-pcache/`.
+
+Quick feature summary
+=====================
+
+* *Write-back* caching (only mode currently supported).
+* *16 MiB segments* allocated on the pmem device.
+* *Data CRC32* verification (optional, per cache).
+* Crash-safe: every metadata structure is duplicated (`PCACHE_META_INDEX_MAX
+  == 2`) and protected with CRC+sequence numbers.
+* *Multi-tree indexing* (indexing trees sharded by logical address) for high PMem parallelism
+* Pure *DAX path* I/O – no extra BIO round-trips
+* *Log-structured write-back* that preserves backend crash-consistency
+
+
+Constructor
+===========
+
+::
+
+    pcache <cache_dev> <backing_dev> [<number_of_optional_arguments> <cache_mode writeback> <data_crc true|false>]
+
+=========================  ====================================================
+``cache_dev``               Any DAX-capable block device (``/dev/pmem0``…).
+                            All metadata *and* cached blocks are stored here.
+
+``backing_dev``             The slow block device to be cached.
+
+``cache_mode``              Optional, Only ``writeback`` is accepted at the
+                            moment.
+
+``data_crc``                Optional, default to ``false``
+
+                            * ``true``  – store CRC32 for every cached entry
+			      and verify on reads
+                            * ``false`` – skip CRC (faster)
+=========================  ====================================================
+
+Example
+-------
+
+.. code-block:: shell
+
+   dmsetup create pcache_sdb --table \
+     "0 $(blockdev --getsz /dev/sdb) pcache /dev/pmem0 /dev/sdb 4 cache_mode writeback data_crc true"
+
+The first time a pmem device is used, dm-pcache formats it automatically
+(super-block, cache_info, etc.).
+
+
+Status line
+===========
+
+``dmsetup status <device>`` (``STATUSTYPE_INFO``) prints:
+
+::
+
+   <sb_flags> <seg_total> <cache_segs> <segs_used> \
+   <gc_percent> <cache_flags> \
+   <key_head_seg>:<key_head_off> \
+   <dirty_tail_seg>:<dirty_tail_off> \
+   <key_tail_seg>:<key_tail_off>
+
+Field meanings
+--------------
+
+===============================  =============================================
+``sb_flags``                     Super-block flags (e.g. endian marker).
+
+``seg_total``                    Number of physical *pmem* segments.
+
+``cache_segs``                   Number of segments used for cache.
+
+``segs_used``                    Segments currently allocated (bitmap weight).
+
+``gc_percent``                   Current GC high-water mark (0-90).
+
+``cache_flags``                  Bit 0 – DATA_CRC enabled
+                                 Bit 1 – INIT_DONE (cache initialised)
+                                 Bits 2-5 – cache mode (0 == WB).
+
+``key_head``                     Where new key-sets are being written.
+
+``dirty_tail``                   First dirty key-set that still needs
+                                 write-back to the backing device.
+
+``key_tail``                     First key-set that may be reclaimed by GC.
+===============================  =============================================
+
+
+Messages
+========
+
+*Change GC trigger*
+
+::
+
+   dmsetup message <dev> 0 gc_percent <0-90>
+
+
+Theory of operation
+===================
+
+Sub-devices
+-----------
+
+====================  =========================================================
+backing_dev             Any block device (SSD/HDD/loop/LVM, etc.).
+cache_dev               DAX device; must expose direct-access memory.
+====================  =========================================================
+
+Segments and key-sets
+---------------------
+
+* The pmem space is divided into *16 MiB segments*.
+* Each write allocates space from a per-CPU *data_head* inside a segment.
+* A *cache-key* records a logical range on the origin and where it lives
+  inside pmem (segment + offset + generation).
+* 128 keys form a *key-set* (kset); ksets are written sequentially in pmem
+  and are themselves crash-safe (CRC).
+* The pair *(key_tail, dirty_tail)* delimit clean/dirty and live/dead ksets.
+
+Write-back
+----------
+
+Dirty keys are queued into a tree; a background worker copies data
+back to the backing_dev and advances *dirty_tail*.  A FLUSH/FUA bio from the
+upper layers forces an immediate metadata commit.
+
+Garbage collection
+------------------
+
+GC starts when ``segs_used >= seg_total * gc_percent / 100``.  It walks
+from *key_tail*, frees segments whose every key has been invalidated, and
+advances *key_tail*.
+
+CRC verification
+----------------
+
+If ``data_crc is enabled`` dm-pcache computes a CRC32 over every cached data
+range when it is inserted and stores it in the on-media key.  Reads
+validate the CRC before copying to the caller.
+
+
+Failure handling
+================
+
+* *pmem media errors* – all metadata copies are read with
+  ``copy_mc_to_kernel``; an uncorrectable error logs and aborts initialisation.
+* *Cache full* – if no free segment can be found, writes return ``-EBUSY``;
+  dm-pcache retries internally (request deferral).
+* *System crash* – on attach, the driver replays ksets from *key_tail* to
+  rebuild the in-core trees; every segment’s generation guards against
+  use-after-free keys.
+
+
+Limitations & TODO
+==================
+
+* Only *write-back* mode; other modes planned.
+* Only FIFO cache invalidate; other (LRU, ARC...) planned.
+* Table reload is not supported currently.
+* Discard planned.
+
+
+Example workflow
+================
+
+.. code-block:: shell
+
+   # 1.  Create devices
+   dmsetup create pcache_sdb --table \
+     "0 $(blockdev --getsz /dev/sdb) pcache /dev/pmem0 /dev/sdb 4 cache_mode writeback data_crc true"
+
+   # 2.  Put a filesystem on top
+   mkfs.ext4 /dev/mapper/pcache_sdb
+   mount /dev/mapper/pcache_sdb /mnt
+
+   # 3.  Tune GC threshold to 80 %
+   dmsetup message pcache_sdb 0 gc_percent 80
+
+   # 4.  Observe status
+   watch -n1 'dmsetup status pcache_sdb'
+
+   # 5.  Shutdown
+   umount /mnt
+   dmsetup remove pcache_sdb
+
+
+``dm-pcache`` is under active development; feedback, bug reports and patches
+are very welcome!
diff --git a/Documentation/admin-guide/device-mapper/dm-queue-length.rst b/Documentation/admin-guide/device-mapper/dm-queue-length.rst
new file mode 100644
index 000000000..d8e381c1c
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-queue-length.rst
@@ -0,0 +1,48 @@
+===============
+dm-queue-length
+===============
+
+dm-queue-length is a path selector module for device-mapper targets,
+which selects a path with the least number of in-flight I/Os.
+The path selector name is 'queue-length'.
+
+Table parameters for each path: [<repeat_count>]
+
+::
+
+	<repeat_count>: The number of I/Os to dispatch using the selected
+			path before switching to the next path.
+			If not given, internal default is used. To check
+			the default value, see the activated table.
+
+Status for each path: <status> <fail-count> <in-flight>
+
+::
+
+	<status>: 'A' if the path is active, 'F' if the path is failed.
+	<fail-count>: The number of path failures.
+	<in-flight>: The number of in-flight I/Os on the path.
+
+
+Algorithm
+=========
+
+dm-queue-length increments/decrements 'in-flight' when an I/O is
+dispatched/completed respectively.
+dm-queue-length selects a path with the minimum 'in-flight'.
+
+
+Examples
+========
+In case that 2 paths (sda and sdb) are used with repeat_count == 128.
+
+::
+
+  # echo "0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128" \
+    dmsetup create test
+  #
+  # dmsetup table
+  test: 0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128
+  #
+  # dmsetup status
+  test: 0 10 multipath 2 0 0 0 1 1 E 0 2 1 8:0 A 0 0 8:16 A 0 0
diff --git a/Documentation/admin-guide/device-mapper/dm-raid.rst b/Documentation/admin-guide/device-mapper/dm-raid.rst
new file mode 100644
index 000000000..3780f6e6b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-raid.rst
@@ -0,0 +1,489 @@
+=======
+dm-raid
+=======
+
+The device-mapper RAID (dm-raid) target provides a bridge from DM to MD.
+It allows the MD RAID drivers to be accessed using a device-mapper
+interface.
+
+
+Mapping Table Interface
+-----------------------
+The target is named "raid" and it accepts the following parameters::
+
+  <raid_type> <#raid_params> <raid_params> \
+    <#raid_devs> <metadata_dev0> <dev0> [.. <metadata_devN> <devN>]
+
+<raid_type>:
+
+  ============= ===============================================================
+  raid0		RAID0 striping (no resilience)
+  raid1		RAID1 mirroring
+  raid4		RAID4 with dedicated last parity disk
+  raid5_n 	RAID5 with dedicated last parity disk supporting takeover from/to raid1
+		Same as raid4
+
+		- Transitory layout for takeover from/to raid1
+  raid5_la	RAID5 left asymmetric
+
+		- rotating parity 0 with data continuation
+  raid5_ra	RAID5 right asymmetric
+
+		- rotating parity N with data continuation
+  raid5_ls	RAID5 left symmetric
+
+		- rotating parity 0 with data restart
+  raid5_rs 	RAID5 right symmetric
+
+		- rotating parity N with data restart
+  raid6_zr	RAID6 zero restart
+
+		- rotating parity zero (left-to-right) with data restart
+  raid6_nr	RAID6 N restart
+
+		- rotating parity N (right-to-left) with data restart
+  raid6_nc	RAID6 N continue
+
+		- rotating parity N (right-to-left) with data continuation
+  raid6_n_6	RAID6 with dedicate parity disks
+
+		- parity and Q-syndrome on the last 2 disks;
+		  layout for takeover from/to raid0/raid4/raid5_n
+  raid6_la_6	Same as "raid_la" plus dedicated last Q-syndrome disk supporting takeover from/to raid5
+
+		- layout for takeover from raid5_la from/to raid6
+  raid6_ra_6	Same as "raid5_ra" dedicated last Q-syndrome disk
+
+		- layout for takeover from raid5_ra from/to raid6
+  raid6_ls_6	Same as "raid5_ls" dedicated last Q-syndrome disk
+
+		- layout for takeover from raid5_ls from/to raid6
+  raid6_rs_6	Same as "raid5_rs" dedicated last Q-syndrome disk
+
+		- layout for takeover from raid5_rs from/to raid6
+  raid10        Various RAID10 inspired algorithms chosen by additional params
+		(see raid10_format and raid10_copies below)
+
+		- RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
+		- RAID1E: Integrated Adjacent Stripe Mirroring
+		- RAID1E: Integrated Offset Stripe Mirroring
+		- and other similar RAID10 variants
+  ============= ===============================================================
+
+  Reference: Chapter 4 of
+  https://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
+
+<#raid_params>: The number of parameters that follow.
+
+<raid_params> consists of
+
+    Mandatory parameters:
+        <chunk_size>:
+		      Chunk size in sectors.  This parameter is often known as
+		      "stripe size".  It is the only mandatory parameter and
+		      is placed first.
+
+    followed by optional parameters (in any order):
+	[sync|nosync]
+		Force or prevent RAID initialization.
+
+	[rebuild <idx>]
+		Rebuild drive number 'idx' (first drive is 0).
+
+	[daemon_sleep <ms>]
+		Interval between runs of the bitmap daemon that
+		clear bits.  A longer interval means less bitmap I/O but
+		resyncing after a failure is likely to take longer.
+
+	[min_recovery_rate <kB/sec/disk>]
+		Throttle RAID initialization
+	[max_recovery_rate <kB/sec/disk>]
+		Throttle RAID initialization
+	[write_mostly <idx>]
+		Mark drive index 'idx' write-mostly.
+	[max_write_behind <sectors>]
+		See '--write-behind=' (man mdadm)
+	[stripe_cache <sectors>]
+		Stripe cache size (RAID 4/5/6 only)
+	[region_size <sectors>]
+		The region_size multiplied by the number of regions is the
+		logical size of the array.  The bitmap records the device
+		synchronisation state for each region.
+
+        [raid10_copies   <# copies>], [raid10_format   <near|far|offset>]
+		These two options are used to alter the default layout of
+		a RAID10 configuration.  The number of copies is can be
+		specified, but the default is 2.  There are also three
+		variations to how the copies are laid down - the default
+		is "near".  Near copies are what most people think of with
+		respect to mirroring.  If these options are left unspecified,
+		or 'raid10_copies 2' and/or 'raid10_format near' are given,
+		then the layouts for 2, 3 and 4 devices	are:
+
+		========	 ==========	   ==============
+		2 drives         3 drives          4 drives
+		========	 ==========	   ==============
+		A1  A1           A1  A1  A2        A1  A1  A2  A2
+		A2  A2           A2  A3  A3        A3  A3  A4  A4
+		A3  A3           A4  A4  A5        A5  A5  A6  A6
+		A4  A4           A5  A6  A6        A7  A7  A8  A8
+		..  ..           ..  ..  ..        ..  ..  ..  ..
+		========	 ==========	   ==============
+
+		The 2-device layout is equivalent 2-way RAID1.  The 4-device
+		layout is what a traditional RAID10 would look like.  The
+		3-device layout is what might be called a 'RAID1E - Integrated
+		Adjacent Stripe Mirroring'.
+
+		If 'raid10_copies 2' and 'raid10_format far', then the layouts
+		for 2, 3 and 4 devices are:
+
+		========	     ============	  ===================
+		2 drives             3 drives             4 drives
+		========	     ============	  ===================
+		A1  A2               A1   A2   A3         A1   A2   A3   A4
+		A3  A4               A4   A5   A6         A5   A6   A7   A8
+		A5  A6               A7   A8   A9         A9   A10  A11  A12
+		..  ..               ..   ..   ..         ..   ..   ..   ..
+		A2  A1               A3   A1   A2         A2   A1   A4   A3
+		A4  A3               A6   A4   A5         A6   A5   A8   A7
+		A6  A5               A9   A7   A8         A10  A9   A12  A11
+		..  ..               ..   ..   ..         ..   ..   ..   ..
+		========	     ============	  ===================
+
+		If 'raid10_copies 2' and 'raid10_format offset', then the
+		layouts for 2, 3 and 4 devices are:
+
+		========       ==========         ================
+		2 drives       3 drives           4 drives
+		========       ==========         ================
+		A1  A2         A1  A2  A3         A1  A2  A3  A4
+		A2  A1         A3  A1  A2         A2  A1  A4  A3
+		A3  A4         A4  A5  A6         A5  A6  A7  A8
+		A4  A3         A6  A4  A5         A6  A5  A8  A7
+		A5  A6         A7  A8  A9         A9  A10 A11 A12
+		A6  A5         A9  A7  A8         A10 A9  A12 A11
+		..  ..         ..  ..  ..         ..  ..  ..  ..
+		========       ==========         ================
+
+		Here we see layouts closely akin to 'RAID1E - Integrated
+		Offset Stripe Mirroring'.
+
+        [delta_disks <N>]
+		The delta_disks option value (-251 < N < +251) triggers
+		device removal (negative value) or device addition (positive
+		value) to any reshape supporting raid levels 4/5/6 and 10.
+		RAID levels 4/5/6 allow for addition and removal of devices
+                (metadata and data device tuple), raid10_near and raid10_offset
+                only allow for device addition. raid10_far does not support any
+		reshaping at all.
+		A minimum of devices have to be kept to enforce resilience,
+		which is 3 devices for raid4/5 and 4 devices for raid6.
+
+        [data_offset <sectors>]
+		This option value defines the offset into each data device
+		where the data starts. This is used to provide out-of-place
+		reshaping space to avoid writing over data while
+		changing the layout of stripes, hence an interruption/crash
+		may happen at any time without the risk of losing data.
+		E.g. when adding devices to an existing raid set during
+		forward reshaping, the out-of-place space will be allocated
+		at the beginning of each raid device. The kernel raid4/5/6/10
+		MD personalities supporting such device addition will read the data from
+		the existing first stripes (those with smaller number of stripes)
+		starting at data_offset to fill up a new stripe with the larger
+		number of stripes, calculate the redundancy blocks (CRC/Q-syndrome)
+		and write that new stripe to offset 0. Same will be applied to all
+		N-1 other new stripes. This out-of-place scheme is used to change
+		the RAID type (i.e. the allocation algorithm) as well, e.g.
+		changing from raid5_ls to raid5_n.
+
+	[journal_dev <dev>]
+		This option adds a journal device to raid4/5/6 raid sets and
+		uses it to close the 'write hole' caused by the non-atomic updates
+		to the component devices which can cause data loss during recovery.
+		The journal device is used as writethrough thus causing writes to
+		be throttled versus non-journaled raid4/5/6 sets.
+		Takeover/reshape is not possible with a raid4/5/6 journal device;
+		it has to be deconfigured before requesting these.
+
+	[journal_mode <mode>]
+		This option sets the caching mode on journaled raid4/5/6 raid sets
+		(see 'journal_dev <dev>' above) to 'writethrough' or 'writeback'.
+		If 'writeback' is selected the journal device has to be resilient
+		and must not suffer from the 'write hole' problem itself (e.g. use
+		raid1 or raid10) to avoid a single point of failure.
+
+<#raid_devs>: The number of devices composing the array.
+	Each device consists of two entries.  The first is the device
+	containing the metadata (if any); the second is the one containing the
+	data. A Maximum of 64 metadata/data device entries are supported
+	up to target version 1.8.0.
+	1.9.0 supports up to 253 which is enforced by the used MD kernel runtime.
+
+	If a drive has failed or is missing at creation time, a '-' can be
+	given for both the metadata and data drives for a given position.
+
+
+Example Tables
+--------------
+
+::
+
+  # RAID4 - 4 data drives, 1 parity (no metadata devices)
+  # No metadata devices specified to hold superblock/bitmap info
+  # Chunk size of 1MiB
+  # (Lines separated for easy reading)
+
+  0 1960893648 raid \
+          raid4 1 2048 \
+          5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
+
+  # RAID4 - 4 data drives, 1 parity (with metadata devices)
+  # Chunk size of 1MiB, force RAID initialization,
+  #       min recovery rate at 20 kiB/sec/disk
+
+  0 1960893648 raid \
+          raid4 4 2048 sync min_recovery_rate 20 \
+          5 8:17 8:18 8:33 8:34 8:49 8:50 8:65 8:66 8:81 8:82
+
+
+Status Output
+-------------
+'dmsetup table' displays the table used to construct the mapping.
+The optional parameters are always printed in the order listed
+above with "sync" or "nosync" always output ahead of the other
+arguments, regardless of the order used when originally loading the table.
+Arguments that can be repeated are ordered by value.
+
+
+'dmsetup status' yields information on the state and health of the array.
+The output is as follows (normally a single line, but expanded here for
+clarity)::
+
+  1: <s> <l> raid \
+  2:      <raid_type> <#devices> <health_chars> \
+  3:      <sync_ratio> <sync_action> <mismatch_cnt>
+
+Line 1 is the standard output produced by device-mapper.
+
+Line 2 & 3 are produced by the raid target and are best explained by example::
+
+        0 1960893648 raid raid4 5 AAAAA 2/490221568 init 0
+
+Here we can see the RAID type is raid4, there are 5 devices - all of
+which are 'A'live, and the array is 2/490221568 complete with its initial
+recovery.  Here is a fuller description of the individual fields:
+
+	=============== =========================================================
+	<raid_type>     Same as the <raid_type> used to create the array.
+	<health_chars>  One char for each device, indicating:
+
+			- 'A' = alive and in-sync
+			- 'a' = alive but not in-sync
+			- 'D' = dead/failed.
+	<sync_ratio>    The ratio indicating how much of the array has undergone
+			the process described by 'sync_action'.  If the
+			'sync_action' is "check" or "repair", then the process
+			of "resync" or "recover" can be considered complete.
+	<sync_action>   One of the following possible states:
+
+			idle
+				- No synchronization action is being performed.
+			frozen
+				- The current action has been halted.
+			resync
+				- Array is undergoing its initial synchronization
+				  or is resynchronizing after an unclean shutdown
+				  (possibly aided by a bitmap).
+			recover
+				- A device in the array is being rebuilt or
+				  replaced.
+			check
+				- A user-initiated full check of the array is
+				  being performed.  All blocks are read and
+				  checked for consistency.  The number of
+				  discrepancies found are recorded in
+				  <mismatch_cnt>.  No changes are made to the
+				  array by this action.
+			repair
+				- The same as "check", but discrepancies are
+				  corrected.
+			reshape
+				- The array is undergoing a reshape.
+	<mismatch_cnt>  The number of discrepancies found between mirror copies
+			in RAID1/10 or wrong parity values found in RAID4/5/6.
+			This value is valid only after a "check" of the array
+			is performed.  A healthy array has a 'mismatch_cnt' of 0.
+	<data_offset>   The current data offset to the start of the user data on
+			each component device of a raid set (see the respective
+			raid parameter to support out-of-place reshaping).
+	<journal_char>	- 'A' - active write-through journal device.
+			- 'a' - active write-back journal device.
+			- 'D' - dead journal device.
+			- '-' - no journal device.
+	=============== =========================================================
+
+
+Message Interface
+-----------------
+The dm-raid target will accept certain actions through the 'message' interface.
+('man dmsetup' for more information on the message interface.)  These actions
+include:
+
+	========= ================================================
+	"idle"    Halt the current sync action.
+	"frozen"  Freeze the current sync action.
+	"resync"  Initiate/continue a resync.
+	"recover" Initiate/continue a recover process.
+	"check"   Initiate a check (i.e. a "scrub") of the array.
+	"repair"  Initiate a repair of the array.
+	========= ================================================
+
+
+Discard Support
+---------------
+The implementation of discard support among hardware vendors varies.
+When a block is discarded, some storage devices will return zeroes when
+the block is read.  These devices set the 'discard_zeroes_data'
+attribute.  Other devices will return random data.  Confusingly, some
+devices that advertise 'discard_zeroes_data' will not reliably return
+zeroes when discarded blocks are read!  Since RAID 4/5/6 uses blocks
+from a number of devices to calculate parity blocks and (for performance
+reasons) relies on 'discard_zeroes_data' being reliable, it is important
+that the devices be consistent.  Blocks may be discarded in the middle
+of a RAID 4/5/6 stripe and if subsequent read results are not
+consistent, the parity blocks may be calculated differently at any time;
+making the parity blocks useless for redundancy.  It is important to
+understand how your hardware behaves with discards if you are going to
+enable discards with RAID 4/5/6.
+
+Since the behavior of storage devices is unreliable in this respect,
+even when reporting 'discard_zeroes_data', by default RAID 4/5/6
+discard support is disabled -- this ensures data integrity at the
+expense of losing some performance.
+
+Storage devices that properly support 'discard_zeroes_data' are
+increasingly whitelisted in the kernel and can thus be trusted.
+
+For trusted devices, the following dm-raid module parameter can be set
+to safely enable discard support for RAID 4/5/6:
+
+    'devices_handle_discards_safely'
+
+
+Takeover/Reshape Support
+------------------------
+The target natively supports these two types of MDRAID conversions:
+
+o Takeover: Converts an array from one RAID level to another
+
+o Reshape: Changes the internal layout while maintaining the current RAID level
+
+Each operation is only valid under specific constraints imposed by the existing array's layout and configuration.
+
+
+Takeover:
+linear -> raid1 with N >= 2 mirrors
+raid0 -> raid4 (add dedicated parity device)
+raid0 -> raid5 (add dedicated parity device)
+raid0 -> raid10 with near layout and N >= 2 mirror groups (raid0 stripes have to become first member within mirror groups)
+raid1 -> linear
+raid1 -> raid5 with 2 mirrors
+raid4 -> raid5 w/ rotating parity
+raid5 with dedicated parity device -> raid4
+raid5 -> raid6 (with dedicated Q-syndrome)
+raid6 (with dedicated Q-syndrome) -> raid5
+raid10 with near layout and even number of disks -> raid0 (select any in-sync device from each mirror group)
+
+Reshape:
+linear: not possible
+raid0:  not possible
+raid1:  change number of mirrors
+raid4:  add and remove stripes (minimum 3), change stripesize
+raid5:  add and remove stripes (minimum 3, special case 2 for raid1 takeover), change rotating parity algorithms, change stripesize
+raid6:  add and remove stripes (minimum 4), change rotating syndrome algorithms, change stripesize
+raid10 near:   add stripes (minimum 4), change stripesize, no stripe removal possible, change to offset layout
+raid10 offset: add stripes, change stripesize, no stripe removal possible, change to near layout
+raid10 far:    not possible
+
+Table line examples:
+
+### raid1 -> raid5
+#
+# 2 devices limitation in raid1.
+# raid5 personality is able to just map 2 like raid1.
+# Reshape after takeover to change to full raid5 layout
+
+  0 1960886272 raid raid1 3 0 region_size 2048 2 /dev/dm-0 /dev/dm-1 /dev/dm-2 /dev/dm-3
+
+# dm-0 and dm-2 are e.g. 4MiB large metadata devices, dm-1 and dm-3 have to be at least 1960886272 big.
+#
+# Table line to takeover to raid5
+
+  0 1960886272 raid raid5 3 0 region_size 2048 2 /dev/dm-0 /dev/dm-1 /dev/dm-2 /dev/dm-3
+
+# Add required out-of-place reshape space to the beginniong of the given 2 data devices,
+# allocate another metadata/data device tuple with the same sizes for the parity space
+# and zero the first 4K of the metadata device.
+#
+# Example table of the out-of-place reshape space addition for one data device, e.g. dm-1
+
+  0 8192 linear 8:0 0 1960903888 #  <- must be free space segment
+  8192 1960886272 linear 8:0 0 2048 # previous data segment
+
+# Mapping table for e.g. raid5_rs reshape causing the size of the raid device to double-fold once the reshape finishes.
+# Check the status output (e.g. "dmsetup status $RaidDev") for progress.
+
+  0 $((2 * 1960886272)) raid raid5 7 0 region_size 2048 data_offset 8192 delta_disk 1 2 /dev/dm-0 /dev/dm-1 /dev/dm-2 /dev/dm-3
+
+
+Version History
+---------------
+
+::
+
+ 1.0.0	Initial version.  Support for RAID 4/5/6
+ 1.1.0	Added support for RAID 1
+ 1.2.0	Handle creation of arrays that contain failed devices.
+ 1.3.0	Added support for RAID 10
+ 1.3.1	Allow device replacement/rebuild for RAID 10
+ 1.3.2	Fix/improve redundancy checking for RAID10
+ 1.4.0	Non-functional change.  Removes arg from mapping function.
+ 1.4.1	RAID10 fix redundancy validation checks (commit 55ebbb5).
+ 1.4.2	Add RAID10 "far" and "offset" algorithm support.
+ 1.5.0	Add message interface to allow manipulation of the sync_action.
+	New status (STATUSTYPE_INFO) fields: sync_action and mismatch_cnt.
+ 1.5.1	Add ability to restore transiently failed devices on resume.
+ 1.5.2	'mismatch_cnt' is zero unless [last_]sync_action is "check".
+ 1.6.0	Add discard support (and devices_handle_discard_safely module param).
+ 1.7.0	Add support for MD RAID0 mappings.
+ 1.8.0	Explicitly check for compatible flags in the superblock metadata
+	and reject to start the raid set if any are set by a newer
+	target version, thus avoiding data corruption on a raid set
+	with a reshape in progress.
+ 1.9.0	Add support for RAID level takeover/reshape/region size
+	and set size reduction.
+ 1.9.1	Fix activation of existing RAID 4/10 mapped devices
+ 1.9.2	Don't emit '- -' on the status table line in case the constructor
+	fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and
+	'D' on the status line.  If '- -' is passed into the constructor, emit
+	'- -' on the table line and '-' as the status line health character.
+ 1.10.0	Add support for raid4/5/6 journal device
+ 1.10.1	Fix data corruption on reshape request
+ 1.11.0	Fix table line argument order
+	(wrong raid10_copies/raid10_format sequence)
+ 1.11.1	Add raid4/5/6 journal write-back support via journal_mode option
+ 1.12.1	Fix for MD deadlock between mddev_suspend() and md_write_start() available
+ 1.13.0	Fix dev_health status at end of "recover" (was 'a', now 'A')
+ 1.13.1	Fix deadlock caused by early md_stop_writes().  Also fix size an
+	state races.
+ 1.13.2	Fix raid redundancy validation and avoid keeping raid set frozen
+ 1.14.0	Fix reshape race on small devices.  Fix stripe adding reshape
+	deadlock/potential data corruption.  Update superblock when
+	specific devices are requested via rebuild.  Fix RAID leg
+	rebuild errors.
+ 1.15.0 Fix size extensions not being synchronized in case of new MD bitmap
+        pages allocated;  also fix those not occurring after previous reductions
+ 1.15.1 Fix argument count and arguments for rebuild/write_mostly/journal_(dev|mode)
+        on the status line.
diff --git a/Documentation/admin-guide/device-mapper/dm-service-time.rst b/Documentation/admin-guide/device-mapper/dm-service-time.rst
new file mode 100644
index 000000000..facf277fc
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-service-time.rst
@@ -0,0 +1,101 @@
+===============
+dm-service-time
+===============
+
+dm-service-time is a path selector module for device-mapper targets,
+which selects a path with the shortest estimated service time for
+the incoming I/O.
+
+The service time for each path is estimated by dividing the total size
+of in-flight I/Os on a path with the performance value of the path.
+The performance value is a relative throughput value among all paths
+in a path-group, and it can be specified as a table argument.
+
+The path selector name is 'service-time'.
+
+Table parameters for each path:
+
+    [<repeat_count> [<relative_throughput>]]
+	<repeat_count>:
+			The number of I/Os to dispatch using the selected
+			path before switching to the next path.
+			If not given, internal default is used.  To check
+			the default value, see the activated table.
+	<relative_throughput>:
+			The relative throughput value of the path
+			among all paths in the path-group.
+			The valid range is 0-100.
+			If not given, minimum value '1' is used.
+			If '0' is given, the path isn't selected while
+			other paths having a positive value are available.
+
+Status for each path:
+
+    <status> <fail-count> <in-flight-size> <relative_throughput>
+	<status>:
+		'A' if the path is active, 'F' if the path is failed.
+	<fail-count>:
+		The number of path failures.
+	<in-flight-size>:
+		The size of in-flight I/Os on the path.
+	<relative_throughput>:
+		The relative throughput value of the path
+		among all paths in the path-group.
+
+
+Algorithm
+=========
+
+dm-service-time adds the I/O size to 'in-flight-size' when the I/O is
+dispatched and subtracts when completed.
+Basically, dm-service-time selects a path having minimum service time
+which is calculated by::
+
+	('in-flight-size' + 'size-of-incoming-io') / 'relative_throughput'
+
+However, some optimizations below are used to reduce the calculation
+as much as possible.
+
+	1. If the paths have the same 'relative_throughput', skip
+	   the division and just compare the 'in-flight-size'.
+
+	2. If the paths have the same 'in-flight-size', skip the division
+	   and just compare the 'relative_throughput'.
+
+	3. If some paths have non-zero 'relative_throughput' and others
+	   have zero 'relative_throughput', ignore those paths with zero
+	   'relative_throughput'.
+
+If such optimizations can't be applied, calculate service time, and
+compare service time.
+If calculated service time is equal, the path having maximum
+'relative_throughput' may be better.  So compare 'relative_throughput'
+then.
+
+
+Examples
+========
+In case that 2 paths (sda and sdb) are used with repeat_count == 128
+and sda has an average throughput 1GB/s and sdb has 4GB/s,
+'relative_throughput' value may be '1' for sda and '4' for sdb::
+
+  # echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4" \
+    dmsetup create test
+  #
+  # dmsetup table
+  test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4
+  #
+  # dmsetup status
+  test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 1 8:16 A 0 0 4
+
+
+Or '2' for sda and '8' for sdb would be also true::
+
+  # echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8" \
+    dmsetup create test
+  #
+  # dmsetup table
+  test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8
+  #
+  # dmsetup status
+  test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 2 8:16 A 0 0 8
diff --git a/Documentation/admin-guide/device-mapper/dm-uevent.rst b/Documentation/admin-guide/device-mapper/dm-uevent.rst
new file mode 100644
index 000000000..4a8ee8d06
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-uevent.rst
@@ -0,0 +1,110 @@
+====================
+device-mapper uevent
+====================
+
+The device-mapper uevent code adds the capability to device-mapper to create
+and send kobject uevents (uevents).  Previously device-mapper events were only
+available through the ioctl interface.  The advantage of the uevents interface
+is the event contains environment attributes providing increased context for
+the event avoiding the need to query the state of the device-mapper device after
+the event is received.
+
+There are two functions currently for device-mapper events.  The first function
+listed creates the event and the second function sends the event(s)::
+
+  void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
+                      const char *path, unsigned nr_valid_paths)
+
+  void dm_send_uevents(struct list_head *events, struct kobject *kobj)
+
+
+The variables added to the uevent environment are:
+
+Variable Name: DM_TARGET
+------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description:
+:Value: Name of device-mapper target that generated the event.
+
+Variable Name: DM_ACTION
+------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description:
+:Value: Device-mapper specific action that caused the uevent action.
+	PATH_FAILED - A path has failed;
+	PATH_REINSTATED - A path has been reinstated.
+
+Variable Name: DM_SEQNUM
+------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: unsigned integer
+:Description: A sequence number for this specific device-mapper device.
+:Value: Valid unsigned integer range.
+
+Variable Name: DM_PATH
+----------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description: Major and minor number of the path device pertaining to this
+	      event.
+:Value: Path name in the form of "Major:Minor"
+
+Variable Name: DM_NR_VALID_PATHS
+--------------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: unsigned integer
+:Description:
+:Value: Valid unsigned integer range.
+
+Variable Name: DM_NAME
+----------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description: Name of the device-mapper device.
+:Value: Name
+
+Variable Name: DM_UUID
+----------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description: UUID of the device-mapper device.
+:Value: UUID. (Empty string if there isn't one.)
+
+An example of the uevents generated as captured by udevmonitor is shown
+below
+
+1.) Path failure::
+
+	UEVENT[1192521009.711215] change@/block/dm-3
+	ACTION=change
+	DEVPATH=/block/dm-3
+	SUBSYSTEM=block
+	DM_TARGET=multipath
+	DM_ACTION=PATH_FAILED
+	DM_SEQNUM=1
+	DM_PATH=8:32
+	DM_NR_VALID_PATHS=0
+	DM_NAME=mpath2
+	DM_UUID=mpath-35333333000002328
+	MINOR=3
+	MAJOR=253
+	SEQNUM=1130
+
+2.) Path reinstate::
+
+	UEVENT[1192521132.989927] change@/block/dm-3
+	ACTION=change
+	DEVPATH=/block/dm-3
+	SUBSYSTEM=block
+	DM_TARGET=multipath
+	DM_ACTION=PATH_REINSTATED
+	DM_SEQNUM=2
+	DM_PATH=8:32
+	DM_NR_VALID_PATHS=1
+	DM_NAME=mpath2
+	DM_UUID=mpath-35333333000002328
+	MINOR=3
+	MAJOR=253
+	SEQNUM=1131
diff --git a/Documentation/admin-guide/device-mapper/dm-zoned.rst b/Documentation/admin-guide/device-mapper/dm-zoned.rst
new file mode 100644
index 000000000..932383fe6
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-zoned.rst
@@ -0,0 +1,194 @@
+========
+dm-zoned
+========
+
+The dm-zoned device mapper target exposes a zoned block device (ZBC and
+ZAC compliant devices) as a regular block device without any write
+pattern constraints. In effect, it implements a drive-managed zoned
+block device which hides from the user (a file system or an application
+doing raw block device accesses) the sequential write constraints of
+host-managed zoned block devices and can mitigate the potential
+device-side performance degradation due to excessive random writes on
+host-aware zoned block devices.
+
+For a more detailed description of the zoned block device models and
+their constraints see (for SCSI devices):
+
+https://www.t10.org/drafts.htm#ZBC_Family
+
+and (for ATA devices):
+
+http://www.t13.org/Documents/UploadedDocuments/docs2015/di537r05-Zoned_Device_ATA_Command_Set_ZAC.pdf
+
+The dm-zoned implementation is simple and minimizes system overhead (CPU
+and memory usage as well as storage capacity loss). For a 10TB
+host-managed disk with 256 MB zones, dm-zoned memory usage per disk
+instance is at most 4.5 MB and as little as 5 zones will be used
+internally for storing metadata and performing reclaim operations.
+
+dm-zoned target devices are formatted and checked using the dmzadm
+utility available at:
+
+https://github.com/hgst/dm-zoned-tools
+
+Algorithm
+=========
+
+dm-zoned implements an on-disk buffering scheme to handle non-sequential
+write accesses to the sequential zones of a zoned block device.
+Conventional zones are used for caching as well as for storing internal
+metadata. It can also use a regular block device together with the zoned
+block device; in that case the regular block device will be split logically
+in zones with the same size as the zoned block device. These zones will be
+placed in front of the zones from the zoned block device and will be handled
+just like conventional zones.
+
+The zones of the device(s) are separated into 2 types:
+
+1) Metadata zones: these are conventional zones used to store metadata.
+Metadata zones are not reported as usable capacity to the user.
+
+2) Data zones: all remaining zones, the vast majority of which will be
+sequential zones used exclusively to store user data. The conventional
+zones of the device may be used also for buffering user random writes.
+Data in these zones may be directly mapped to the conventional zone, but
+later moved to a sequential zone so that the conventional zone can be
+reused for buffering incoming random writes.
+
+dm-zoned exposes a logical device with a sector size of 4096 bytes,
+irrespective of the physical sector size of the backend zoned block
+device being used. This allows reducing the amount of metadata needed to
+manage valid blocks (blocks written).
+
+The on-disk metadata format is as follows:
+
+1) The first block of the first conventional zone found contains the
+super block which describes the on disk amount and position of metadata
+blocks.
+
+2) Following the super block, a set of blocks is used to describe the
+mapping of the logical device blocks. The mapping is done per chunk of
+blocks, with the chunk size equal to the zoned block device size. The
+mapping table is indexed by chunk number and each mapping entry
+indicates the zone number of the device storing the chunk of data. Each
+mapping entry may also indicate if the zone number of a conventional
+zone used to buffer random modification to the data zone.
+
+3) A set of blocks used to store bitmaps indicating the validity of
+blocks in the data zones follows the mapping table. A valid block is
+defined as a block that was written and not discarded. For a buffered
+data chunk, a block is always valid only in the data zone mapping the
+chunk or in the buffer zone of the chunk.
+
+For a logical chunk mapped to a conventional zone, all write operations
+are processed by directly writing to the zone. If the mapping zone is a
+sequential zone, the write operation is processed directly only if the
+write offset within the logical chunk is equal to the write pointer
+offset within of the sequential data zone (i.e. the write operation is
+aligned on the zone write pointer). Otherwise, write operations are
+processed indirectly using a buffer zone. In that case, an unused
+conventional zone is allocated and assigned to the chunk being
+accessed. Writing a block to the buffer zone of a chunk will
+automatically invalidate the same block in the sequential zone mapping
+the chunk. If all blocks of the sequential zone become invalid, the zone
+is freed and the chunk buffer zone becomes the primary zone mapping the
+chunk, resulting in native random write performance similar to a regular
+block device.
+
+Read operations are processed according to the block validity
+information provided by the bitmaps. Valid blocks are read either from
+the sequential zone mapping a chunk, or if the chunk is buffered, from
+the buffer zone assigned. If the accessed chunk has no mapping, or the
+accessed blocks are invalid, the read buffer is zeroed and the read
+operation terminated.
+
+After some time, the limited number of conventional zones available may
+be exhausted (all used to map chunks or buffer sequential zones) and
+unaligned writes to unbuffered chunks become impossible. To avoid this
+situation, a reclaim process regularly scans used conventional zones and
+tries to reclaim the least recently used zones by copying the valid
+blocks of the buffer zone to a free sequential zone. Once the copy
+completes, the chunk mapping is updated to point to the sequential zone
+and the buffer zone freed for reuse.
+
+Metadata Protection
+===================
+
+To protect metadata against corruption in case of sudden power loss or
+system crash, 2 sets of metadata zones are used. One set, the primary
+set, is used as the main metadata region, while the secondary set is
+used as a staging area. Modified metadata is first written to the
+secondary set and validated by updating the super block in the secondary
+set, a generation counter is used to indicate that this set contains the
+newest metadata. Once this operation completes, in place of metadata
+block updates can be done in the primary metadata set. This ensures that
+one of the set is always consistent (all modifications committed or none
+at all). Flush operations are used as a commit point. Upon reception of
+a flush request, metadata modification activity is temporarily blocked
+(for both incoming BIO processing and reclaim process) and all dirty
+metadata blocks are staged and updated. Normal operation is then
+resumed. Flushing metadata thus only temporarily delays write and
+discard requests. Read requests can be processed concurrently while
+metadata flush is being executed.
+
+If a regular device is used in conjunction with the zoned block device,
+a third set of metadata (without the zone bitmaps) is written to the
+start of the zoned block device. This metadata has a generation counter of
+'0' and will never be updated during normal operation; it just serves for
+identification purposes. The first and second copy of the metadata
+are located at the start of the regular block device.
+
+Usage
+=====
+
+A zoned block device must first be formatted using the dmzadm tool. This
+will analyze the device zone configuration, determine where to place the
+metadata sets on the device and initialize the metadata sets.
+
+Ex::
+
+	dmzadm --format /dev/sdxx
+
+
+If two drives are to be used, both devices must be specified, with the
+regular block device as the first device.
+
+Ex::
+
+	dmzadm --format /dev/sdxx /dev/sdyy
+
+
+Formatted device(s) can be started with the dmzadm utility, too.:
+
+Ex::
+
+	dmzadm --start /dev/sdxx /dev/sdyy
+
+
+Information about the internal layout and current usage of the zones can
+be obtained with the 'status' callback from dmsetup:
+
+Ex::
+
+	dmsetup status /dev/dm-X
+
+will return a line
+
+	0 <size> zoned <nr_zones> zones <nr_unmap_rnd>/<nr_rnd> random <nr_unmap_seq>/<nr_seq> sequential
+
+where <nr_zones> is the total number of zones, <nr_unmap_rnd> is the number
+of unmapped (ie free) random zones, <nr_rnd> the total number of zones,
+<nr_unmap_seq> the number of unmapped sequential zones, and <nr_seq> the
+total number of sequential zones.
+
+Normally the reclaim process will be started once there are less than 50
+percent free random zones. In order to start the reclaim process manually
+even before reaching this threshold the 'dmsetup message' function can be
+used:
+
+Ex::
+
+	dmsetup message /dev/dm-X 0 reclaim
+
+will start the reclaim process and random zones will be moved to sequential
+zones.
diff --git a/Documentation/admin-guide/device-mapper/era.rst b/Documentation/admin-guide/device-mapper/era.rst
new file mode 100644
index 000000000..90dd5c670
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/era.rst
@@ -0,0 +1,116 @@
+======
+dm-era
+======
+
+Introduction
+============
+
+dm-era is a target that behaves similar to the linear target.  In
+addition it keeps track of which blocks were written within a user
+defined period of time called an 'era'.  Each era target instance
+maintains the current era as a monotonically increasing 32-bit
+counter.
+
+Use cases include tracking changed blocks for backup software, and
+partially invalidating the contents of a cache to restore cache
+coherency after rolling back a vendor snapshot.
+
+Constructor
+===========
+
+era <metadata dev> <origin dev> <block size>
+
+ ================ ======================================================
+ metadata dev     fast device holding the persistent metadata
+ origin dev	  device holding data blocks that may change
+ block size       block size of origin data device, granularity that is
+		  tracked by the target
+ ================ ======================================================
+
+Messages
+========
+
+None of the dm messages take any arguments.
+
+checkpoint
+----------
+
+Possibly move to a new era.  You shouldn't assume the era has
+incremented.  After sending this message, you should check the
+current era via the status line.
+
+take_metadata_snap
+------------------
+
+Create a clone of the metadata, to allow a userland process to read it.
+
+drop_metadata_snap
+------------------
+
+Drop the metadata snapshot.
+
+Status
+======
+
+<metadata block size> <#used metadata blocks>/<#total metadata blocks>
+<current era> <held metadata root | '-'>
+
+========================= ==============================================
+metadata block size	  Fixed block size for each metadata block in
+			  sectors
+#used metadata blocks	  Number of metadata blocks used
+#total metadata blocks	  Total number of metadata blocks
+current era		  The current era
+held metadata root	  The location, in blocks, of the metadata root
+			  that has been 'held' for userspace read
+			  access. '-' indicates there is no held root
+========================= ==============================================
+
+Detailed use case
+=================
+
+The scenario of invalidating a cache when rolling back a vendor
+snapshot was the primary use case when developing this target:
+
+Taking a vendor snapshot
+------------------------
+
+- Send a checkpoint message to the era target
+- Make a note of the current era in its status line
+- Take vendor snapshot (the era and snapshot should be forever
+  associated now).
+
+Rolling back to an vendor snapshot
+----------------------------------
+
+- Cache enters passthrough mode (see: dm-cache's docs in cache.txt)
+- Rollback vendor storage
+- Take metadata snapshot
+- Ascertain which blocks have been written since the snapshot was taken
+  by checking each block's era
+- Invalidate those blocks in the caching software
+- Cache returns to writeback/writethrough mode
+
+Memory usage
+============
+
+The target uses a bitset to record writes in the current era.  It also
+has a spare bitset ready for switching over to a new era.  Other than
+that it uses a few 4k blocks for updating metadata::
+
+   (4 * nr_blocks) bytes + buffers
+
+Resilience
+==========
+
+Metadata is updated on disk before a write to a previously unwritten
+block is performed.  As such dm-era should not be effected by a hard
+crash such as power failure.
+
+Userland tools
+==============
+
+Userland tools are found in the increasingly poorly named
+thin-provisioning-tools project:
+
+    https://github.com/jthornber/thin-provisioning-tools
diff --git a/Documentation/admin-guide/device-mapper/index.rst b/Documentation/admin-guide/device-mapper/index.rst
new file mode 100644
index 000000000..73c1f2002
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/index.rst
@@ -0,0 +1,43 @@
+=============
+Device Mapper
+=============
+
+.. toctree::
+    :maxdepth: 1
+
+    cache-policies
+    cache
+    delay
+    dm-clone
+    dm-crypt
+    dm-dust
+    dm-ebs
+    dm-flakey
+    dm-ima
+    dm-init
+    dm-inlinecrypt
+    dm-integrity
+    dm-io
+    dm-log
+    dm-pcache
+    dm-queue-length
+    dm-raid
+    dm-service-time
+    dm-uevent
+    dm-zoned
+    era
+    kcopyd
+    linear
+    log-writes
+    persistent-data
+    snapshot
+    statistics
+    striped
+    switch
+    thin-provisioning
+    unstriped
+    vdo-design
+    vdo
+    verity
+    writecache
+    zero
diff --git a/Documentation/admin-guide/device-mapper/kcopyd.rst b/Documentation/admin-guide/device-mapper/kcopyd.rst
new file mode 100644
index 000000000..7651d3951
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/kcopyd.rst
@@ -0,0 +1,47 @@
+======
+kcopyd
+======
+
+Kcopyd provides the ability to copy a range of sectors from one block-device
+to one or more other block-devices, with an asynchronous completion
+notification. It is used by dm-snapshot and dm-mirror.
+
+Users of kcopyd must first create a client and indicate how many memory pages
+to set aside for their copy jobs. This is done with a call to
+kcopyd_client_create()::
+
+   int kcopyd_client_create(unsigned int num_pages,
+                            struct kcopyd_client **result);
+
+To start a copy job, the user must set up io_region structures to describe
+the source and destinations of the copy. Each io_region indicates a
+block-device along with the starting sector and size of the region. The source
+of the copy is given as one io_region structure, and the destinations of the
+copy are given as an array of io_region structures::
+
+   struct io_region {
+      struct block_device *bdev;
+      sector_t sector;
+      sector_t count;
+   };
+
+To start the copy, the user calls kcopyd_copy(), passing in the client
+pointer, pointers to the source and destination io_regions, the name of a
+completion callback routine, and a pointer to some context data for the copy::
+
+   int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from,
+                   unsigned int num_dests, struct io_region *dests,
+                   unsigned int flags, kcopyd_notify_fn fn, void *context);
+
+   typedef void (*kcopyd_notify_fn)(int read_err, unsigned int write_err,
+				    void *context);
+
+When the copy completes, kcopyd will call the user's completion routine,
+passing back the user's context pointer. It will also indicate if a read or
+write error occurred during the copy.
+
+When a user is done with all their copy jobs, they should call
+kcopyd_client_destroy() to delete the kcopyd client, which will release the
+associated memory pages::
+
+   void kcopyd_client_destroy(struct kcopyd_client *kc);
diff --git a/Documentation/admin-guide/device-mapper/linear.rst b/Documentation/admin-guide/device-mapper/linear.rst
new file mode 100644
index 000000000..9d17fc6e6
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/linear.rst
@@ -0,0 +1,63 @@
+=========
+dm-linear
+=========
+
+Device-Mapper's "linear" target maps a linear range of the Device-Mapper
+device onto a linear range of another device.  This is the basic building
+block of logical volume managers.
+
+Parameters: <dev path> <offset>
+    <dev path>:
+	Full pathname to the underlying block-device, or a
+        "major:minor" device-number.
+    <offset>:
+	Starting sector within the device.
+
+
+Example scripts
+===============
+
+::
+
+  #!/bin/sh
+  # Create an identity mapping for a device
+  echo "0 `blockdev --getsz $1` linear $1 0" | dmsetup create identity
+
+::
+
+  #!/bin/sh
+  # Join 2 devices together
+  size1=`blockdev --getsz $1`
+  size2=`blockdev --getsz $2`
+  echo "0 $size1 linear $1 0
+  $size1 $size2 linear $2 0" | dmsetup create joined
+
+::
+
+  #!/usr/bin/perl -w
+  # Split a device into 4M chunks and then join them together in reverse order.
+
+  my $name = "reverse";
+  my $extent_size = 4 * 1024 * 2;
+  my $dev = $ARGV[0];
+  my $table = "";
+  my $count = 0;
+
+  if (!defined($dev)) {
+          die("Please specify a device.\n");
+  }
+
+  my $dev_size = `blockdev --getsz $dev`;
+  my $extents = int($dev_size / $extent_size) -
+                (($dev_size % $extent_size) ? 1 : 0);
+
+  while ($extents > 0) {
+          my $this_start = $count * $extent_size;
+          $extents--;
+          $count++;
+          my $this_offset = $extents * $extent_size;
+
+          $table .= "$this_start $extent_size linear $dev $this_offset\n";
+  }
+
+  `echo \"$table\" | dmsetup create $name`;
diff --git a/Documentation/admin-guide/device-mapper/log-writes.rst b/Documentation/admin-guide/device-mapper/log-writes.rst
new file mode 100644
index 000000000..23141f2ff
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/log-writes.rst
@@ -0,0 +1,145 @@
+=============
+dm-log-writes
+=============
+
+This target takes 2 devices, one to pass all IO to normally, and one to log all
+of the write operations to.  This is intended for file system developers wishing
+to verify the integrity of metadata or data as the file system is written to.
+There is a log_write_entry written for every WRITE request and the target is
+able to take arbitrary data from userspace to insert into the log.  The data
+that is in the WRITE requests is copied into the log to make the replay happen
+exactly as it happened originally.
+
+Log Ordering
+============
+
+We log things in order of completion once we are sure the write is no longer in
+cache.  This means that normal WRITE requests are not actually logged until the
+next REQ_PREFLUSH request.  This is to make it easier for userspace to replay
+the log in a way that correlates to what is on disk and not what is in cache,
+to make it easier to detect improper waiting/flushing.
+
+This works by attaching all WRITE requests to a list once the write completes.
+Once we see a REQ_PREFLUSH request we splice this list onto the request and once
+the FLUSH request completes we log all of the WRITEs and then the FLUSH.  Only
+completed WRITEs, at the time the REQ_PREFLUSH is issued, are added in order to
+simulate the worst case scenario with regard to power failures.  Consider the
+following example (W means write, C means complete):
+
+	W1,W2,W3,C3,C2,Wflush,C1,Cflush
+
+The log would show the following:
+
+	W3,W2,flush,W1....
+
+Again this is to simulate what is actually on disk, this allows us to detect
+cases where a power failure at a particular point in time would create an
+inconsistent file system.
+
+Any REQ_FUA requests bypass this flushing mechanism and are logged as soon as
+they complete as those requests will obviously bypass the device cache.
+
+Any REQ_OP_DISCARD requests are treated like WRITE requests.  Otherwise we would
+have all the DISCARD requests, and then the WRITE requests and then the FLUSH
+request.  Consider the following example:
+
+	WRITE block 1, DISCARD block 1, FLUSH
+
+If we logged DISCARD when it completed, the replay would look like this:
+
+	DISCARD 1, WRITE 1, FLUSH
+
+which isn't quite what happened and wouldn't be caught during the log replay.
+
+Target interface
+================
+
+i) Constructor
+
+   log-writes <dev_path> <log_dev_path>
+
+   ============= ==============================================
+   dev_path	 Device that all of the IO will go to normally.
+   log_dev_path  Device where the log entries are written to.
+   ============= ==============================================
+
+ii) Status
+
+    <#logged entries> <highest allocated sector>
+
+    =========================== ========================
+    #logged entries	        Number of logged entries
+    highest allocated sector    Highest allocated sector
+    =========================== ========================
+
+iii) Messages
+
+    mark <description>
+
+	You can use a dmsetup message to set an arbitrary mark in a log.
+	For example say you want to fsck a file system after every
+	write, but first you need to replay up to the mkfs to make sure
+	we're fsck'ing something reasonable, you would do something like
+	this::
+
+	  mkfs.btrfs -f /dev/mapper/log
+	  dmsetup message log 0 mark mkfs
+	  <run test>
+
+	This would allow you to replay the log up to the mkfs mark and
+	then replay from that point on doing the fsck check in the
+	interval that you want.
+
+	Every log has a mark at the end labeled "dm-log-writes-end".
+
+Userspace component
+===================
+
+There is a userspace tool that will replay the log for you in various ways.
+It can be found here: https://github.com/josefbacik/log-writes
+
+Example usage
+=============
+
+Say you want to test fsync on your file system.  You would do something like
+this::
+
+  TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
+  dmsetup create log --table "$TABLE"
+  mkfs.btrfs -f /dev/mapper/log
+  dmsetup message log 0 mark mkfs
+
+  mount /dev/mapper/log /mnt/btrfs-test
+  <some test that does fsync at the end>
+  dmsetup message log 0 mark fsync
+  md5sum /mnt/btrfs-test/foo
+  umount /mnt/btrfs-test
+
+  dmsetup remove log
+  replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync
+  mount /dev/sdb /mnt/btrfs-test
+  md5sum /mnt/btrfs-test/foo
+  <verify md5sum's are correct>
+
+  Another option is to do a complicated file system operation and verify the file
+  system is consistent during the entire operation.  You could do this with:
+
+  TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
+  dmsetup create log --table "$TABLE"
+  mkfs.btrfs -f /dev/mapper/log
+  dmsetup message log 0 mark mkfs
+
+  mount /dev/mapper/log /mnt/btrfs-test
+  <fsstress to dirty the fs>
+  btrfs filesystem balance /mnt/btrfs-test
+  umount /mnt/btrfs-test
+  dmsetup remove log
+
+  replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs
+  btrfsck /dev/sdb
+  replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \
+	--fsck "btrfsck /dev/sdb" --check fua
+
+And that will replay the log until it sees a FUA request, run the fsck command
+and if the fsck passes it will replay to the next FUA, until it is completed or
+the fsck command exists abnormally.
diff --git a/Documentation/admin-guide/device-mapper/persistent-data.rst b/Documentation/admin-guide/device-mapper/persistent-data.rst
new file mode 100644
index 000000000..2065c3c5a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/persistent-data.rst
@@ -0,0 +1,88 @@
+===============
+Persistent data
+===============
+
+Introduction
+============
+
+The more-sophisticated device-mapper targets require complex metadata
+that is managed in kernel.  In late 2010 we were seeing that various
+different targets were rolling their own data structures, for example:
+
+- Mikulas Patocka's multisnap implementation
+- Heinz Mauelshagen's thin provisioning target
+- Another btree-based caching target posted to dm-devel
+- Another multi-snapshot target based on a design of Daniel Phillips
+
+Maintaining these data structures takes a lot of work, so if possible
+we'd like to reduce the number.
+
+The persistent-data library is an attempt to provide a re-usable
+framework for people who want to store metadata in device-mapper
+targets.  It's currently used by the thin-provisioning target and an
+upcoming hierarchical storage target.
+
+Overview
+========
+
+The main documentation is in the header files which can all be found
+under drivers/md/persistent-data.
+
+The block manager
+-----------------
+
+dm-block-manager.[hc]
+
+This provides access to the data on disk in fixed sized-blocks.  There
+is a read/write locking interface to prevent concurrent accesses, and
+keep data that is being used in the cache.
+
+Clients of persistent-data are unlikely to use this directly.
+
+The transaction manager
+-----------------------
+
+dm-transaction-manager.[hc]
+
+This restricts access to blocks and enforces copy-on-write semantics.
+The only way you can get hold of a writable block through the
+transaction manager is by shadowing an existing block (ie. doing
+copy-on-write) or allocating a fresh one.  Shadowing is elided within
+the same transaction so performance is reasonable.  The commit method
+ensures that all data is flushed before it writes the superblock.
+On power failure your metadata will be as it was when last committed.
+
+The Space Maps
+--------------
+
+dm-space-map.h
+dm-space-map-metadata.[hc]
+dm-space-map-disk.[hc]
+
+On-disk data structures that keep track of reference counts of blocks.
+Also acts as the allocator of new blocks.  Currently two
+implementations: a simpler one for managing blocks on a different
+device (eg. thinly-provisioned data blocks); and one for managing
+the metadata space.  The latter is complicated by the need to store
+its own data within the space it's managing.
+
+The data structures
+-------------------
+
+dm-btree.[hc]
+dm-btree-remove.c
+dm-btree-spine.c
+dm-btree-internal.h
+
+Currently there is only one data structure, a hierarchical btree.
+There are plans to add more.  For example, something with an
+array-like interface would see a lot of use.
+
+The btree is 'hierarchical' in that you can define it to be composed
+of nested btrees, and take multiple keys.  For example, the
+thin-provisioning target uses a btree with two levels of nesting.
+The first maps a device id to a mapping tree, and that in turn maps a
+virtual block to a physical block.
+
+Values stored in the btrees can have arbitrary size.  Keys are always
+64bits, although nesting allows you to use multiple keys.
diff --git a/Documentation/admin-guide/device-mapper/snapshot.rst b/Documentation/admin-guide/device-mapper/snapshot.rst
new file mode 100644
index 000000000..ccdd8b587
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/snapshot.rst
@@ -0,0 +1,196 @@
+==============================
+Device-mapper snapshot support
+==============================
+
+Device-mapper allows you, without massive data copying:
+
+-  To create snapshots of any block device i.e. mountable, saved states of
+   the block device which are also writable without interfering with the
+   original content;
+-  To create device "forks", i.e. multiple different versions of the
+   same data stream.
+-  To merge a snapshot of a block device back into the snapshot's origin
+   device.
+
+In the first two cases, dm copies only the chunks of data that get
+changed and uses a separate copy-on-write (COW) block device for
+storage.
+
+For snapshot merge the contents of the COW storage are merged back into
+the origin device.
+
+
+There are three dm targets available:
+snapshot, snapshot-origin, and snapshot-merge.
+
+-  snapshot-origin <origin>
+
+which will normally have one or more snapshots based on it.
+Reads will be mapped directly to the backing device. For each write, the
+original data will be saved in the <COW device> of each snapshot to keep
+its visible content unchanged, at least until the <COW device> fills up.
+
+
+-  snapshot <origin> <COW device> <persistent?> <chunksize>
+   [<# feature args> [<arg>]*]
+
+A snapshot of the <origin> block device is created. Changed chunks of
+<chunksize> sectors will be stored on the <COW device>.  Writes will
+only go to the <COW device>.  Reads will come from the <COW device> or
+from <origin> for unchanged data.  <COW device> will often be
+smaller than the origin and if it fills up the snapshot will become
+useless and be disabled, returning errors.  So it is important to monitor
+the amount of free space and expand the <COW device> before it fills up.
+
+<persistent?> is P (Persistent) or N (Not persistent - will not survive
+after reboot).  O (Overflow) can be added as a persistent store option
+to allow userspace to advertise its support for seeing "Overflow" in the
+snapshot status.  So supported store types are "P", "PO" and "N".
+
+The difference between persistent and transient is with transient
+snapshots less metadata must be saved on disk - they can be kept in
+memory by the kernel.
+
+When loading or unloading the snapshot target, the corresponding
+snapshot-origin or snapshot-merge target must be suspended. A failure to
+suspend the origin target could result in data corruption.
+
+Optional features:
+
+   discard_zeroes_cow - a discard issued to the snapshot device that
+   maps to entire chunks to will zero the corresponding exception(s) in
+   the snapshot's exception store.
+
+   discard_passdown_origin - a discard to the snapshot device is passed
+   down to the snapshot-origin's underlying device.  This doesn't cause
+   copy-out to the snapshot exception store because the snapshot-origin
+   target is bypassed.
+
+   The discard_passdown_origin feature depends on the discard_zeroes_cow
+   feature being enabled.
+
+
+-  snapshot-merge <origin> <COW device> <persistent> <chunksize>
+   [<# feature args> [<arg>]*]
+
+takes the same table arguments as the snapshot target except it only
+works with persistent snapshots.  This target assumes the role of the
+"snapshot-origin" target and must not be loaded if the "snapshot-origin"
+is still present for <origin>.
+
+Creates a merging snapshot that takes control of the changed chunks
+stored in the <COW device> of an existing snapshot, through a handover
+procedure, and merges these chunks back into the <origin>.  Once merging
+has started (in the background) the <origin> may be opened and the merge
+will continue while I/O is flowing to it.  Changes to the <origin> are
+deferred until the merging snapshot's corresponding chunk(s) have been
+merged.  Once merging has started the snapshot device, associated with
+the "snapshot" target, will return -EIO when accessed.
+
+
+How snapshot is used by LVM2
+============================
+When you create the first LVM2 snapshot of a volume, four dm devices are used:
+
+1) a device containing the original mapping table of the source volume;
+2) a device used as the <COW device>;
+3) a "snapshot" device, combining #1 and #2, which is the visible snapshot
+   volume;
+4) the "original" volume (which uses the device number used by the original
+   source volume), whose table is replaced by a "snapshot-origin" mapping
+   from device #1.
+
+A fixed naming scheme is used, so with the following commands::
+
+  lvcreate -L 1G -n base volumeGroup
+  lvcreate -L 100M --snapshot -n snap volumeGroup/base
+
+we'll have this situation (with volumes in above order)::
+
+  # dmsetup table|grep volumeGroup
+
+  volumeGroup-base-real: 0 2097152 linear 8:19 384
+  volumeGroup-snap-cow: 0 204800 linear 8:19 2097536
+  volumeGroup-snap: 0 2097152 snapshot 254:11 254:12 P 16
+  volumeGroup-base: 0 2097152 snapshot-origin 254:11
+
+  # ls -lL /dev/mapper/volumeGroup-*
+  brw-------  1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
+  brw-------  1 root root 254, 12 29 ago 18:15 /dev/mapper/volumeGroup-snap-cow
+  brw-------  1 root root 254, 13 29 ago 18:15 /dev/mapper/volumeGroup-snap
+  brw-------  1 root root 254, 10 29 ago 18:14 /dev/mapper/volumeGroup-base
+
+
+How snapshot-merge is used by LVM2
+==================================
+A merging snapshot assumes the role of the "snapshot-origin" while
+merging.  As such the "snapshot-origin" is replaced with
+"snapshot-merge".  The "-real" device is not changed and the "-cow"
+device is renamed to <origin name>-cow to aid LVM2's cleanup of the
+merging snapshot after it completes.  The "snapshot" that hands over its
+COW device to the "snapshot-merge" is deactivated (unless using lvchange
+--refresh); but if it is left active it will simply return I/O errors.
+
+A snapshot will merge into its origin with the following command::
+
+  lvconvert --merge volumeGroup/snap
+
+we'll now have this situation::
+
+  # dmsetup table|grep volumeGroup
+
+  volumeGroup-base-real: 0 2097152 linear 8:19 384
+  volumeGroup-base-cow: 0 204800 linear 8:19 2097536
+  volumeGroup-base: 0 2097152 snapshot-merge 254:11 254:12 P 16
+
+  # ls -lL /dev/mapper/volumeGroup-*
+  brw-------  1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
+  brw-------  1 root root 254, 12 29 ago 18:16 /dev/mapper/volumeGroup-base-cow
+  brw-------  1 root root 254, 10 29 ago 18:16 /dev/mapper/volumeGroup-base
+
+
+How to determine when a merging is complete
+===========================================
+The snapshot-merge and snapshot status lines end with:
+
+  <sectors_allocated>/<total_sectors> <metadata_sectors>
+
+Both <sectors_allocated> and <total_sectors> include both data and metadata.
+During merging, the number of sectors allocated gets smaller and
+smaller.  Merging has finished when the number of sectors holding data
+is zero, in other words <sectors_allocated> == <metadata_sectors>.
+
+Here is a practical example (using a hybrid of lvm and dmsetup commands)::
+
+  # lvs
+    LV      VG          Attr   LSize Origin  Snap%  Move Log Copy%  Convert
+    base    volumeGroup owi-a- 4.00g
+    snap    volumeGroup swi-a- 1.00g base  18.97
+
+  # dmsetup status volumeGroup-snap
+  0 8388608 snapshot 397896/2097152 1560
+                                    ^^^^ metadata sectors
+
+  # lvconvert --merge -b volumeGroup/snap
+    Merging of volume snap started.
+
+  # lvs volumeGroup/snap
+    LV      VG          Attr   LSize Origin  Snap%  Move Log Copy%  Convert
+    base    volumeGroup Owi-a- 4.00g          17.23
+
+  # dmsetup status volumeGroup-base
+  0 8388608 snapshot-merge 281688/2097152 1104
+
+  # dmsetup status volumeGroup-base
+  0 8388608 snapshot-merge 180480/2097152 712
+
+  # dmsetup status volumeGroup-base
+  0 8388608 snapshot-merge 16/2097152 16
+
+Merging has finished.
+
+::
+
+  # lvs
+    LV      VG          Attr   LSize Origin  Snap%  Move Log Copy%  Convert
+    base    volumeGroup owi-a- 4.00g
diff --git a/Documentation/admin-guide/device-mapper/statistics.rst b/Documentation/admin-guide/device-mapper/statistics.rst
new file mode 100644
index 000000000..41ded0bc5
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/statistics.rst
@@ -0,0 +1,225 @@
+=============
+DM statistics
+=============
+
+Device Mapper supports the collection of I/O statistics on user-defined
+regions of a DM device.	 If no regions are defined no statistics are
+collected so there isn't any performance impact.  Only bio-based DM
+devices are currently supported.
+
+Each user-defined region specifies a starting sector, length and step.
+Individual statistics will be collected for each step-sized area within
+the range specified.
+
+The I/O statistics counters for each step-sized area of a region are
+in the same format as `/sys/block/*/stat` or `/proc/diskstats` (see:
+Documentation/admin-guide/iostats.rst).  But two extra counters (12 and 13) are
+provided: total time spent reading and writing.  When the histogram
+argument is used, the 14th parameter is reported that represents the
+histogram of latencies.  All these counters may be accessed by sending
+the @stats_print message to the appropriate DM device via dmsetup.
+
+The reported times are in milliseconds and the granularity depends on
+the kernel ticks.  When the option precise_timestamps is used, the
+reported times are in nanoseconds.
+
+Each region has a corresponding unique identifier, which we call a
+region_id, that is assigned when the region is created.	 The region_id
+must be supplied when querying statistics about the region, deleting the
+region, etc.  Unique region_ids enable multiple userspace programs to
+request and process statistics for the same DM device without stepping
+on each other's data.
+
+The creation of DM statistics will allocate memory via kmalloc or
+fallback to using vmalloc space.  At most, 1/4 of the overall system
+memory may be allocated by DM statistics.  The admin can see how much
+memory is used by reading:
+
+	/sys/module/dm_mod/parameters/stats_current_allocated_bytes
+
+Messages
+========
+
+    @stats_create <range> <step> [<number_of_optional_arguments> <optional_arguments>...] [<program_id> [<aux_data>]]
+	Create a new region and return the region_id.
+
+	<range>
+	  "-"
+		whole device
+	  "<start_sector>+<length>"
+		a range of <length> 512-byte sectors
+		starting with <start_sector>.
+
+	<step>
+	  "<area_size>"
+		the range is subdivided into areas each containing
+		<area_size> sectors.
+	  "/<number_of_areas>"
+		the range is subdivided into the specified
+		number of areas.
+
+	<number_of_optional_arguments>
+	  The number of optional arguments
+
+	<optional_arguments>
+	  The following optional arguments are supported:
+
+	  precise_timestamps
+		use precise timer with nanosecond resolution
+		instead of the "jiffies" variable.  When this argument is
+		used, the resulting times are in nanoseconds instead of
+		milliseconds.  Precise timestamps are a little bit slower
+		to obtain than jiffies-based timestamps.
+	  histogram:n1,n2,n3,n4,...
+		collect histogram of latencies.  The
+		numbers n1, n2, etc are times that represent the boundaries
+		of the histogram.  If precise_timestamps is not used, the
+		times are in milliseconds, otherwise they are in
+		nanoseconds.  For each range, the kernel will report the
+		number of requests that completed within this range. For
+		example, if we use "histogram:10,20,30", the kernel will
+		report four numbers a:b:c:d. a is the number of requests
+		that took 0-10 ms to complete, b is the number of requests
+		that took 10-20 ms to complete, c is the number of requests
+		that took 20-30 ms to complete and d is the number of
+		requests that took more than 30 ms to complete.
+
+	<program_id>
+	  An optional parameter.  A name that uniquely identifies
+	  the userspace owner of the range.  This groups ranges together
+	  so that userspace programs can identify the ranges they
+	  created and ignore those created by others.
+	  The kernel returns this string back in the output of
+	  @stats_list message, but it doesn't use it for anything else.
+	  If we omit the number of optional arguments, program id must not
+	  be a number, otherwise it would be interpreted as the number of
+	  optional arguments.
+
+	<aux_data>
+	  An optional parameter.  A word that provides auxiliary data
+	  that is useful to the client program that created the range.
+	  The kernel returns this string back in the output of
+	  @stats_list message, but it doesn't use this value for anything.
+
+    @stats_delete <region_id>
+	Delete the region with the specified id.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+    @stats_clear <region_id>
+	Clear all the counters except the in-flight i/o counters.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+    @stats_list [<program_id>]
+	List all regions registered with @stats_create.
+
+	<program_id>
+	  An optional parameter.
+	  If this parameter is specified, only matching regions
+	  are returned.
+	  If it is not specified, all regions are returned.
+
+	Output format:
+	  <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
+	        precise_timestamps histogram:n1,n2,n3,...
+
+	The strings "precise_timestamps" and "histogram" are printed only
+	if they were specified when creating the region.
+
+    @stats_print <region_id> [<starting_line> <number_of_lines>]
+	Print counters for each step-sized area of a region.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+	<starting_line>
+	  The index of the starting line in the output.
+	  If omitted, all lines are returned.
+
+	<number_of_lines>
+	  The number of lines to include in the output.
+	  If omitted, all lines are returned.
+
+	Output format for each step-sized area of a region:
+
+	  <start_sector>+<length>
+		counters
+
+	  The first 11 counters have the same meaning as
+	  `/sys/block/*/stat or /proc/diskstats`.
+
+	  Please refer to Documentation/admin-guide/iostats.rst for details.
+
+	  1. the number of reads completed
+	  2. the number of reads merged
+	  3. the number of sectors read
+	  4. the number of milliseconds spent reading
+	  5. the number of writes completed
+	  6. the number of writes merged
+	  7. the number of sectors written
+	  8. the number of milliseconds spent writing
+	  9. the number of I/Os currently in progress
+	  10. the number of milliseconds spent doing I/Os
+	  11. the weighted number of milliseconds spent doing I/Os
+
+	  Additional counters:
+
+	  12. the total time spent reading in milliseconds
+	  13. the total time spent writing in milliseconds
+
+    @stats_print_clear <region_id> [<starting_line> <number_of_lines>]
+	Atomically print and then clear all the counters except the
+	in-flight i/o counters.	 Useful when the client consuming the
+	statistics does not want to lose any statistics (those updated
+	between printing and clearing).
+
+	<region_id>
+	  region_id returned from @stats_create
+
+	<starting_line>
+	  The index of the starting line in the output.
+	  If omitted, all lines are printed and then cleared.
+
+	<number_of_lines>
+	  The number of lines to process.
+	  If omitted, all lines are printed and then cleared.
+
+    @stats_set_aux <region_id> <aux_data>
+	Store auxiliary data aux_data for the specified region.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+	<aux_data>
+	  The string that identifies data which is useful to the client
+	  program that created the range.  The kernel returns this
+	  string back in the output of @stats_list message, but it
+	  doesn't use this value for anything.
+
+Examples
+========
+
+Subdivide the DM device 'vol' into 100 pieces and start collecting
+statistics on them::
+
+  dmsetup message vol 0 @stats_create - /100
+
+Set the auxiliary data string to "foo bar baz" (the escape for each
+space must also be escaped, otherwise the shell will consume them)::
+
+  dmsetup message vol 0 @stats_set_aux 0 foo\\ bar\\ baz
+
+List the statistics::
+
+  dmsetup message vol 0 @stats_list
+
+Print the statistics::
+
+  dmsetup message vol 0 @stats_print 0
+
+Delete the statistics::
+
+  dmsetup message vol 0 @stats_delete 0
diff --git a/Documentation/admin-guide/device-mapper/striped.rst b/Documentation/admin-guide/device-mapper/striped.rst
new file mode 100644
index 000000000..e9a8da192
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/striped.rst
@@ -0,0 +1,61 @@
+=========
+dm-stripe
+=========
+
+Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0)
+device across one or more underlying devices. Data is written in "chunks",
+with consecutive chunks rotating among the underlying devices. This can
+potentially provide improved I/O throughput by utilizing several physical
+devices in parallel.
+
+Parameters: <num devs> <chunk size> [<dev path> <offset>]+
+    <num devs>:
+	Number of underlying devices.
+    <chunk size>:
+	Size of each chunk of data. Must be at least as
+        large as the system's PAGE_SIZE.
+    <dev path>:
+	Full pathname to the underlying block-device, or a
+	"major:minor" device-number.
+    <offset>:
+	Starting sector within the device.
+
+One or more underlying devices can be specified. The striped device size must
+be a multiple of the chunk size multiplied by the number of underlying devices.
+
+
+Example scripts
+===============
+
+::
+
+  #!/usr/bin/perl -w
+  # Create a striped device across any number of underlying devices. The device
+  # will be called "stripe_dev" and have a chunk-size of 128k.
+
+  my $chunk_size = 128 * 2;
+  my $dev_name = "stripe_dev";
+  my $num_devs = @ARGV;
+  my @devs = @ARGV;
+  my ($min_dev_size, $stripe_dev_size, $i);
+
+  if (!$num_devs) {
+          die("Specify at least one device\n");
+  }
+
+  $min_dev_size = `blockdev --getsz $devs[0]`;
+  for ($i = 1; $i < $num_devs; $i++) {
+          my $this_size = `blockdev --getsz $devs[$i]`;
+          $min_dev_size = ($min_dev_size < $this_size) ?
+                          $min_dev_size : $this_size;
+  }
+
+  $stripe_dev_size = $min_dev_size * $num_devs;
+  $stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs);
+
+  $table = "0 $stripe_dev_size striped $num_devs $chunk_size";
+  for ($i = 0; $i < $num_devs; $i++) {
+          $table .= " $devs[$i] 0";
+  }
+
+  `echo $table | dmsetup create $dev_name`;
diff --git a/Documentation/admin-guide/device-mapper/switch.rst b/Documentation/admin-guide/device-mapper/switch.rst
new file mode 100644
index 000000000..7dde06be1
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/switch.rst
@@ -0,0 +1,141 @@
+=========
+dm-switch
+=========
+
+The device-mapper switch target creates a device that supports an
+arbitrary mapping of fixed-size regions of I/O across a fixed set of
+paths.  The path used for any specific region can be switched
+dynamically by sending the target a message.
+
+It maps I/O to underlying block devices efficiently when there is a large
+number of fixed-sized address regions but there is no simple pattern
+that would allow for a compact representation of the mapping such as
+dm-stripe.
+
+Background
+----------
+
+Dell EqualLogic and some other iSCSI storage arrays use a distributed
+frameless architecture.  In this architecture, the storage group
+consists of a number of distinct storage arrays ("members") each having
+independent controllers, disk storage and network adapters.  When a LUN
+is created it is spread across multiple members.  The details of the
+spreading are hidden from initiators connected to this storage system.
+The storage group exposes a single target discovery portal, no matter
+how many members are being used.  When iSCSI sessions are created, each
+session is connected to an eth port on a single member.  Data to a LUN
+can be sent on any iSCSI session, and if the blocks being accessed are
+stored on another member the I/O will be forwarded as required.  This
+forwarding is invisible to the initiator.  The storage layout is also
+dynamic, and the blocks stored on disk may be moved from member to
+member as needed to balance the load.
+
+This architecture simplifies the management and configuration of both
+the storage group and initiators.  In a multipathing configuration, it
+is possible to set up multiple iSCSI sessions to use multiple network
+interfaces on both the host and target to take advantage of the
+increased network bandwidth.  An initiator could use a simple round
+robin algorithm to send I/O across all paths and let the storage array
+members forward it as necessary, but there is a performance advantage to
+sending data directly to the correct member.
+
+A device-mapper table already lets you map different regions of a
+device onto different targets.  However in this architecture the LUN is
+spread with an address region size on the order of 10s of MBs, which
+means the resulting table could have more than a million entries and
+consume far too much memory.
+
+Using this device-mapper switch target we can now build a two-layer
+device hierarchy:
+
+    Upper Tier - Determine which array member the I/O should be sent to.
+    Lower Tier - Load balance amongst paths to a particular member.
+
+The lower tier consists of a single dm multipath device for each member.
+Each of these multipath devices contains the set of paths directly to
+the array member in one priority group, and leverages existing path
+selectors to load balance amongst these paths.  We also build a
+non-preferred priority group containing paths to other array members for
+failover reasons.
+
+The upper tier consists of a single dm-switch device.  This device uses
+a bitmap to look up the location of the I/O and choose the appropriate
+lower tier device to route the I/O.  By using a bitmap we are able to
+use 4 bits for each address range in a 16 member group (which is very
+large for us).  This is a much denser representation than the dm table
+b-tree can achieve.
+
+Construction Parameters
+=======================
+
+    <num_paths> <region_size> <num_optional_args> [<optional_args>...] [<dev_path> <offset>]+
+	<num_paths>
+	    The number of paths across which to distribute the I/O.
+
+	<region_size>
+	    The number of 512-byte sectors in a region. Each region can be redirected
+	    to any of the available paths.
+
+	<num_optional_args>
+	    The number of optional arguments. Currently, no optional arguments
+	    are supported and so this must be zero.
+
+	<dev_path>
+	    The block device that represents a specific path to the device.
+
+	<offset>
+	    The offset of the start of data on the specific <dev_path> (in units
+	    of 512-byte sectors). This number is added to the sector number when
+	    forwarding the request to the specific path. Typically it is zero.
+
+Messages
+========
+
+set_region_mappings <index>:<path_nr> [<index>]:<path_nr> [<index>]:<path_nr>...
+
+Modify the region table by specifying which regions are redirected to
+which paths.
+
+<index>
+    The region number (region size was specified in constructor parameters).
+    If index is omitted, the next region (previous index + 1) is used.
+    Expressed in hexadecimal (WITHOUT any prefix like 0x).
+
+<path_nr>
+    The path number in the range 0 ... (<num_paths> - 1).
+    Expressed in hexadecimal (WITHOUT any prefix like 0x).
+
+R<n>,<m>
+    This parameter allows repetitive patterns to be loaded quickly. <n> and <m>
+    are hexadecimal numbers. The last <n> mappings are repeated in the next <m>
+    slots.
+
+Status
+======
+
+No status line is reported.
+
+Example
+=======
+
+Assume that you have volumes vg1/switch0 vg1/switch1 vg1/switch2 with
+the same size.
+
+Create a switch device with 64kB region size::
+
+    dmsetup create switch --table "0 `blockdev --getsz /dev/vg1/switch0`
+	switch 3 128 0 /dev/vg1/switch0 0 /dev/vg1/switch1 0 /dev/vg1/switch2 0"
+
+Set mappings for the first 7 entries to point to devices switch0, switch1,
+switch2, switch0, switch1, switch2, switch1::
+
+    dmsetup message switch 0 set_region_mappings 0:0 :1 :2 :0 :1 :2 :1
+
+Set repetitive mapping. This command::
+
+    dmsetup message switch 0 set_region_mappings 1000:1 :2 R2,10
+
+is equivalent to::
+
+    dmsetup message switch 0 set_region_mappings 1000:1 :2 :1 :2 :1 :2 :1 :2 \
+	:1 :2 :1 :2 :1 :2 :1 :2 :1 :2
diff --git a/Documentation/admin-guide/device-mapper/thin-provisioning.rst b/Documentation/admin-guide/device-mapper/thin-provisioning.rst
new file mode 100644
index 000000000..b2fa49a56
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/thin-provisioning.rst
@@ -0,0 +1,427 @@
+=================
+Thin provisioning
+=================
+
+Introduction
+============
+
+This document describes a collection of device-mapper targets that
+between them implement thin-provisioning and snapshots.
+
+The main highlight of this implementation, compared to the previous
+implementation of snapshots, is that it allows many virtual devices to
+be stored on the same data volume.  This simplifies administration and
+allows the sharing of data between volumes, thus reducing disk usage.
+
+Another significant feature is support for an arbitrary depth of
+recursive snapshots (snapshots of snapshots of snapshots ...).  The
+previous implementation of snapshots did this by chaining together
+lookup tables, and so performance was O(depth).  This new
+implementation uses a single data structure to avoid this degradation
+with depth.  Fragmentation may still be an issue, however, in some
+scenarios.
+
+Metadata is stored on a separate device from data, giving the
+administrator some freedom, for example to:
+
+- Improve metadata resilience by storing metadata on a mirrored volume
+  but data on a non-mirrored one.
+
+- Improve performance by storing the metadata on SSD.
+
+Status
+======
+
+These targets are considered safe for production use.  But different use
+cases will have different performance characteristics, for example due
+to fragmentation of the data volume.
+
+If you find this software is not performing as expected please mail
+dm-devel@redhat.com with details and we'll try our best to improve
+things for you.
+
+Userspace tools for checking and repairing the metadata have been fully
+developed and are available as 'thin_check' and 'thin_repair'.  The name
+of the package that provides these utilities varies by distribution (on
+a Red Hat distribution it is named 'device-mapper-persistent-data').
+
+Cookbook
+========
+
+This section describes some quick recipes for using thin provisioning.
+They use the dmsetup program to control the device-mapper driver
+directly.  End users will be advised to use a higher-level volume
+manager such as LVM2 once support has been added.
+
+Pool device
+-----------
+
+The pool device ties together the metadata volume and the data volume.
+It maps I/O linearly to the data volume and updates the metadata via
+two mechanisms:
+
+- Function calls from the thin targets
+
+- Device-mapper 'messages' from userspace which control the creation of new
+  virtual devices amongst other things.
+
+Setting up a fresh pool device
+------------------------------
+
+Setting up a pool device requires a valid metadata device, and a
+data device.  If you do not have an existing metadata device you can
+make one by zeroing the first 4k to indicate empty metadata.
+
+    dd if=/dev/zero of=$metadata_dev bs=4096 count=1
+
+The amount of metadata you need will vary according to how many blocks
+are shared between thin devices (i.e. through snapshots).  If you have
+less sharing than average you'll need a larger-than-average metadata device.
+
+As a guide, we suggest you calculate the number of bytes to use in the
+metadata device as 48 * $data_dev_size / $data_block_size but round it up
+to 2MiB if the answer is smaller.  If you're creating large numbers of
+snapshots which are recording large amounts of change, you may find you
+need to increase this.
+
+The largest size supported is 16GiB: If the device is larger,
+a warning will be issued and the excess space will not be used.
+
+Reloading a pool table
+----------------------
+
+You may reload a pool's table, indeed this is how the pool is resized
+if it runs out of space.  (N.B. While specifying a different metadata
+device when reloading is not forbidden at the moment, things will go
+wrong if it does not route I/O to exactly the same on-disk location as
+previously.)
+
+Using an existing pool device
+-----------------------------
+
+::
+
+    dmsetup create pool \
+	--table "0 20971520 thin-pool $metadata_dev $data_dev \
+		 $data_block_size $low_water_mark"
+
+$data_block_size gives the smallest unit of disk space that can be
+allocated at a time expressed in units of 512-byte sectors.
+$data_block_size must be between 128 (64KiB) and 2097152 (1GiB) and a
+multiple of 128 (64KiB).  $data_block_size cannot be changed after the
+thin-pool is created.  People primarily interested in thin provisioning
+may want to use a value such as 1024 (512KiB).  People doing lots of
+snapshotting may want a smaller value such as 128 (64KiB).  If you are
+not zeroing newly-allocated data, a larger $data_block_size in the
+region of 262144 (128MiB) is suggested.
+
+$low_water_mark is expressed in blocks of size $data_block_size.  If
+free space on the data device drops below this level then a dm event
+will be triggered which a userspace daemon should catch allowing it to
+extend the pool device.  Only one such event will be sent.
+
+No special event is triggered if a just resumed device's free space is below
+the low water mark. However, resuming a device always triggers an
+event; a userspace daemon should verify that free space exceeds the low
+water mark when handling this event.
+
+A low water mark for the metadata device is maintained in the kernel and
+will trigger a dm event if free space on the metadata device drops below
+it.
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written.
+If no such requests are made then commits will occur every second.  This
+means the thin-provisioning target behaves like a physical disk that has
+a volatile write cache.  If power is lost you may lose some recent
+writes.  The metadata should always be consistent in spite of any crash.
+
+If data space is exhausted the pool will either error or queue IO
+according to the configuration (see: error_if_no_space).  If metadata
+space is exhausted or a metadata operation fails: the pool will error IO
+until the pool is taken offline and repair is performed to 1) fix any
+potential inconsistencies and 2) clear the flag that imposes repair.
+Once the pool's metadata device is repaired it may be resized, which
+will allow the pool to return to normal operation.  Note that if a pool
+is flagged as needing repair, the pool's data and metadata devices
+cannot be resized until repair is performed.  It should also be noted
+that when the pool's metadata space is exhausted the current metadata
+transaction is aborted.  Given that the pool will cache IO whose
+completion may have already been acknowledged to upper IO layers
+(e.g. filesystem) it is strongly suggested that consistency checks
+(e.g. fsck) be performed on those layers when repair of the pool is
+required.
+
+Thin provisioning
+-----------------
+
+i) Creating a new thinly-provisioned volume.
+
+  To create a new thinly- provisioned volume you must send a message to an
+  active pool device, /dev/mapper/pool in this example::
+
+    dmsetup message /dev/mapper/pool 0 "create_thin 0"
+
+  Here '0' is an identifier for the volume, a 24-bit number.  It's up
+  to the caller to allocate and manage these identifiers.  If the
+  identifier is already in use, the message will fail with -EEXIST.
+
+ii) Using a thinly-provisioned volume.
+
+  Thinly-provisioned volumes are activated using the 'thin' target::
+
+    dmsetup create thin --table "0 2097152 thin /dev/mapper/pool 0"
+
+  The last parameter is the identifier for the thinp device.
+
+Internal snapshots
+------------------
+
+i) Creating an internal snapshot.
+
+  Snapshots are created with another message to the pool.
+
+  N.B.  If the origin device that you wish to snapshot is active, you
+  must suspend it before creating the snapshot to avoid corruption.
+  This is NOT enforced at the moment, so please be careful!
+
+  ::
+
+    dmsetup suspend /dev/mapper/thin
+    dmsetup message /dev/mapper/pool 0 "create_snap 1 0"
+    dmsetup resume /dev/mapper/thin
+
+  Here '1' is the identifier for the volume, a 24-bit number.  '0' is the
+  identifier for the origin device.
+
+ii) Using an internal snapshot.
+
+  Once created, the user doesn't have to worry about any connection
+  between the origin and the snapshot.  Indeed the snapshot is no
+  different from any other thinly-provisioned device and can be
+  snapshotted itself via the same method.  It's perfectly legal to
+  have only one of them active, and there's no ordering requirement on
+  activating or removing them both.  (This differs from conventional
+  device-mapper snapshots.)
+
+  Activate it exactly the same way as any other thinly-provisioned volume::
+
+    dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 1"
+
+External snapshots
+------------------
+
+You can use an external **read only** device as an origin for a
+thinly-provisioned volume.  Any read to an unprovisioned area of the
+thin device will be passed through to the origin.  Writes trigger
+the allocation of new blocks as usual.
+
+One use case for this is VM hosts that want to run guests on
+thinly-provisioned volumes but have the base image on another device
+(possibly shared between many VMs).
+
+You must not write to the origin device if you use this technique!
+Of course, you may write to the thin device and take internal snapshots
+of the thin volume.
+
+i) Creating a snapshot of an external device
+
+  This is the same as creating a thin device.
+  You don't mention the origin at this stage.
+
+  ::
+
+    dmsetup message /dev/mapper/pool 0 "create_thin 0"
+
+ii) Using a snapshot of an external device.
+
+  Append an extra parameter to the thin target specifying the origin::
+
+    dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 0 /dev/image"
+
+  N.B. All descendants (internal snapshots) of this snapshot require the
+  same extra origin parameter.
+
+Deactivation
+------------
+
+All devices using a pool must be deactivated before the pool itself
+can be.
+
+::
+
+    dmsetup remove thin
+    dmsetup remove snap
+    dmsetup remove pool
+
+Reference
+=========
+
+'thin-pool' target
+------------------
+
+i) Constructor
+
+    ::
+
+      thin-pool <metadata dev> <data dev> <data block size (sectors)> \
+	        <low water mark (blocks)> [<number of feature args> [<arg>]*]
+
+    Optional feature arguments:
+
+      skip_block_zeroing:
+	Skip the zeroing of newly-provisioned blocks.
+
+      ignore_discard:
+	Disable discard support.
+
+      no_discard_passdown:
+	Don't pass discards down to the underlying
+	data device, but just remove the mapping.
+
+      read_only:
+		 Don't allow any changes to be made to the pool
+		 metadata.  This mode is only available after the
+		 thin-pool has been created and first used in full
+		 read/write mode.  It cannot be specified on initial
+		 thin-pool creation.
+
+      error_if_no_space:
+	Error IOs, instead of queueing, if no space.
+
+    Data block size must be between 64KiB (128 sectors) and 1GiB
+    (2097152 sectors) inclusive.
+
+
+ii) Status
+
+    ::
+
+      <transaction id> <used metadata blocks>/<total metadata blocks>
+      <used data blocks>/<total data blocks> <held metadata root>
+      ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space
+      needs_check|- metadata_low_watermark
+
+    transaction id:
+	A 64-bit number used by userspace to help synchronise with metadata
+	from volume managers.
+
+    used data blocks / total data blocks
+	If the number of free blocks drops below the pool's low water mark a
+	dm event will be sent to userspace.  This event is edge-triggered and
+	it will occur only once after each resume so volume manager writers
+	should register for the event and then check the target's status.
+
+    held metadata root:
+	The location, in blocks, of the metadata root that has been
+	'held' for userspace read access.  '-' indicates there is no
+	held root.
+
+    discard_passdown|no_discard_passdown
+	Whether or not discards are actually being passed down to the
+	underlying device.  When this is enabled when loading the table,
+	it can get disabled if the underlying device doesn't support it.
+
+    ro|rw|out_of_data_space
+	If the pool encounters certain types of device failures it will
+	drop into a read-only metadata mode in which no changes to
+	the pool metadata (like allocating new blocks) are permitted.
+
+	In serious cases where even a read-only mode is deemed unsafe
+	no further I/O will be permitted and the status will just
+	contain the string 'Fail'.  The userspace recovery tools
+	should then be used.
+
+    error_if_no_space|queue_if_no_space
+	If the pool runs out of data or metadata space, the pool will
+	either queue or error the IO destined to the data device.  The
+	default is to queue the IO until more space is added or the
+	'no_space_timeout' expires.  The 'no_space_timeout' dm-thin-pool
+	module parameter can be used to change this timeout -- it
+	defaults to 60 seconds but may be disabled using a value of 0.
+
+    needs_check
+	A metadata operation has failed, resulting in the needs_check
+	flag being set in the metadata's superblock.  The metadata
+	device must be deactivated and checked/repaired before the
+	thin-pool can be made fully operational again.  '-' indicates
+	needs_check is not set.
+
+    metadata_low_watermark:
+	Value of metadata low watermark in blocks.  The kernel sets this
+	value internally but userspace needs to know this value to
+	determine if an event was caused by crossing this threshold.
+
+iii) Messages
+
+    create_thin <dev id>
+	Create a new thinly-provisioned device.
+	<dev id> is an arbitrary unique 24-bit identifier chosen by
+	the caller.
+
+    create_snap <dev id> <origin id>
+	Create a new snapshot of another thinly-provisioned device.
+	<dev id> is an arbitrary unique 24-bit identifier chosen by
+	the caller.
+	<origin id> is the identifier of the thinly-provisioned device
+	of which the new device will be a snapshot.
+
+    delete <dev id>
+	Deletes a thin device.  Irreversible.
+
+    set_transaction_id <current id> <new id>
+	Userland volume managers, such as LVM, need a way to
+	synchronise their external metadata with the internal metadata of the
+	pool target.  The thin-pool target offers to store an
+	arbitrary 64-bit transaction id and return it on the target's
+	status line.  To avoid races you must provide what you think
+	the current transaction id is when you change it with this
+	compare-and-swap message.
+
+    reserve_metadata_snap
+        Reserve a copy of the data mapping btree for use by userland.
+        This allows userland to inspect the mappings as they were when
+        this message was executed.  Use the pool's status command to
+        get the root block associated with the metadata snapshot.
+
+    release_metadata_snap
+        Release a previously reserved copy of the data mapping btree.
+
+'thin' target
+-------------
+
+i) Constructor
+
+    ::
+
+        thin <pool dev> <dev id> [<external origin dev>]
+
+    pool dev:
+	the thin-pool device, e.g. /dev/mapper/my_pool or 253:0
+
+    dev id:
+	the internal device identifier of the device to be
+	activated.
+
+    external origin dev:
+	an optional block device outside the pool to be treated as a
+	read-only snapshot origin: reads to unprovisioned areas of the
+	thin target will be mapped to this device.
+
+The pool doesn't store any size against the thin devices.  If you
+load a thin target that is smaller than you've been using previously,
+then you'll have no access to blocks mapped beyond the end.  If you
+load a target that is bigger than before, then extra blocks will be
+provisioned as and when needed.
+
+ii) Status
+
+    <nr mapped sectors> <highest mapped sector>
+	If the pool has encountered device errors and failed, the status
+	will just contain the string 'Fail'.  The userspace recovery
+	tools should then be used.
+
+    In the case where <nr mapped sectors> is 0, there is no highest
+    mapped sector and the value of <highest mapped sector> is unspecified.
diff --git a/Documentation/admin-guide/device-mapper/unstriped.rst b/Documentation/admin-guide/device-mapper/unstriped.rst
new file mode 100644
index 000000000..5772ccdd1
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/unstriped.rst
@@ -0,0 +1,135 @@
+================================
+Device-mapper "unstriped" target
+================================
+
+Introduction
+============
+
+The device-mapper "unstriped" target provides a transparent mechanism to
+unstripe a device-mapper "striped" target to access the underlying disks
+without having to touch the true backing block-device.  It can also be
+used to unstripe a hardware RAID-0 to access backing disks.
+
+Parameters:
+<number of stripes> <chunk size> <stripe #> <dev_path> <offset>
+
+<number of stripes>
+        The number of stripes in the RAID 0.
+
+<chunk size>
+	The amount of 512B sectors in the chunk striping.
+
+<dev_path>
+	The block device you wish to unstripe.
+
+<stripe #>
+        The stripe number within the device that corresponds to physical
+        drive you wish to unstripe.  This must be 0 indexed.
+
+
+Why use this module?
+====================
+
+An example of undoing an existing dm-stripe
+-------------------------------------------
+
+This small bash script will setup 4 loop devices and use the existing
+striped target to combine the 4 devices into one.  It then will use
+the unstriped target on top of the striped device to access the
+individual backing loop devices.  We write data to the newly exposed
+unstriped devices and verify the data written matches the correct
+underlying device on the striped array::
+
+  #!/bin/bash
+
+  MEMBER_SIZE=$((128 * 1024 * 1024))
+  NUM=4
+  SEQ_END=$((${NUM}-1))
+  CHUNK=256
+  BS=4096
+
+  RAID_SIZE=$((${MEMBER_SIZE}*${NUM}/512))
+  DM_PARMS="0 ${RAID_SIZE} striped ${NUM} ${CHUNK}"
+  COUNT=$((${MEMBER_SIZE} / ${BS}))
+
+  for i in $(seq 0 ${SEQ_END}); do
+    dd if=/dev/zero of=member-${i} bs=${MEMBER_SIZE} count=1 oflag=direct
+    losetup /dev/loop${i} member-${i}
+    DM_PARMS+=" /dev/loop${i} 0"
+  done
+
+  echo $DM_PARMS | dmsetup create raid0
+  for i in $(seq 0 ${SEQ_END}); do
+    echo "0 1 unstriped ${NUM} ${CHUNK} ${i} /dev/mapper/raid0 0" | dmsetup create set-${i}
+  done;
+
+  for i in $(seq 0 ${SEQ_END}); do
+    dd if=/dev/urandom of=/dev/mapper/set-${i} bs=${BS} count=${COUNT} oflag=direct
+    diff /dev/mapper/set-${i} member-${i}
+  done;
+
+  for i in $(seq 0 ${SEQ_END}); do
+    dmsetup remove set-${i}
+  done
+
+  dmsetup remove raid0
+
+  for i in $(seq 0 ${SEQ_END}); do
+    losetup -d /dev/loop${i}
+    rm -f member-${i}
+  done
+
+Another example
+---------------
+
+Intel NVMe drives contain two cores on the physical device.
+Each core of the drive has segregated access to its LBA range.
+The current LBA model has a RAID 0 128k chunk on each core, resulting
+in a 256k stripe across the two cores::
+
+   Core 0:       Core 1:
+  __________    __________
+  | LBA 512|    | LBA 768|
+  | LBA 0  |    | LBA 256|
+  ----------    ----------
+
+The purpose of this unstriping is to provide better QoS in noisy
+neighbor environments. When two partitions are created on the
+aggregate drive without this unstriping, reads on one partition
+can affect writes on another partition.  This is because the partitions
+are striped across the two cores.  When we unstripe this hardware RAID 0
+and make partitions on each new exposed device the two partitions are now
+physically separated.
+
+With the dm-unstriped target we're able to segregate an fio script that
+has read and write jobs that are independent of each other.  Compared to
+when we run the test on a combined drive with partitions, we were able
+to get a 92% reduction in read latency using this device mapper target.
+
+
+Example dmsetup usage
+=====================
+
+unstriped on top of Intel NVMe device that has 2 cores
+------------------------------------------------------
+
+::
+
+  dmsetup create nvmset0 --table '0 512 unstriped 2 256 0 /dev/nvme0n1 0'
+  dmsetup create nvmset1 --table '0 512 unstriped 2 256 1 /dev/nvme0n1 0'
+
+There will now be two devices that expose Intel NVMe core 0 and 1
+respectively::
+
+  /dev/mapper/nvmset0
+  /dev/mapper/nvmset1
+
+unstriped on top of striped with 4 drives using 128K chunk size
+---------------------------------------------------------------
+
+::
+
+  dmsetup create raid_disk0 --table '0 512 unstriped 4 256 0 /dev/mapper/striped 0'
+  dmsetup create raid_disk1 --table '0 512 unstriped 4 256 1 /dev/mapper/striped 0'
+  dmsetup create raid_disk2 --table '0 512 unstriped 4 256 2 /dev/mapper/striped 0'
+  dmsetup create raid_disk3 --table '0 512 unstriped 4 256 3 /dev/mapper/striped 0'
diff --git a/Documentation/admin-guide/device-mapper/vdo-design.rst b/Documentation/admin-guide/device-mapper/vdo-design.rst
new file mode 100644
index 000000000..faa0ecd4a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/vdo-design.rst
@@ -0,0 +1,633 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+================
+Design of dm-vdo
+================
+
+The dm-vdo (virtual data optimizer) target provides inline deduplication,
+compression, zero-block elimination, and thin provisioning. A dm-vdo target
+can be backed by up to 256TB of storage, and can present a logical size of
+up to 4PB. This target was originally developed at Permabit Technology
+Corp. starting in 2009. It was first released in 2013 and has been used in
+production environments ever since. It was made open-source in 2017 after
+Permabit was acquired by Red Hat. This document describes the design of
+dm-vdo. For usage, see vdo.rst in the same directory as this file.
+
+Because deduplication rates fall drastically as the block size increases, a
+vdo target has a maximum block size of 4K. However, it can achieve
+deduplication rates of 254:1, i.e. up to 254 copies of a given 4K block can
+reference a single 4K of actual storage. It can achieve compression rates
+of 14:1. All zero blocks consume no storage at all.
+
+Theory of Operation
+===================
+
+The design of dm-vdo is based on the idea that deduplication is a two-part
+problem. The first is to recognize duplicate data. The second is to avoid
+storing multiple copies of those duplicates. Therefore, dm-vdo has two main
+parts: a deduplication index (called UDS) that is used to discover
+duplicate data, and a data store with a reference counted block map that
+maps from logical block addresses to the actual storage location of the
+data.
+
+Zones and Threading
+-------------------
+
+Due to the complexity of data optimization, the number of metadata
+structures involved in a single write operation to a vdo target is larger
+than most other targets. Furthermore, because vdo must operate on small
+block sizes in order to achieve good deduplication rates, acceptable
+performance can only be achieved through parallelism. Therefore, vdo's
+design attempts to be lock-free.
+
+Most of a vdo's main data structures are designed to be easily divided into
+"zones" such that any given bio must only access a single zone of any zoned
+structure. Safety with minimal locking is achieved by ensuring that during
+normal operation, each zone is assigned to a specific thread, and only that
+thread will access the portion of the data structure in that zone.
+Associated with each thread is a work queue. Each bio is associated with a
+request object (the "data_vio") which will be added to a work queue when
+the next phase of its operation requires access to the structures in the
+zone associated with that queue.
+
+Another way of thinking about this arrangement is that the work queue for
+each zone has an implicit lock on the structures it manages for all its
+operations, because vdo guarantees that no other thread will alter those
+structures.
+
+Although each structure is divided into zones, this division is not
+reflected in the on-disk representation of each data structure. Therefore,
+the number of zones for each structure, and hence the number of threads,
+can be reconfigured each time a vdo target is started.
+
+The Deduplication Index
+-----------------------
+
+In order to identify duplicate data efficiently, vdo was designed to
+leverage some common characteristics of duplicate data. From empirical
+observations, we gathered two key insights. The first is that in most data
+sets with significant amounts of duplicate data, the duplicates tend to
+have temporal locality. When a duplicate appears, it is more likely that
+other duplicates will be detected, and that those duplicates will have been
+written at about the same time. This is why the index keeps records in
+temporal order. The second insight is that new data is more likely to
+duplicate recent data than it is to duplicate older data and in general,
+there are diminishing returns to looking further back in time. Therefore,
+when the index is full, it should cull its oldest records to make space for
+new ones. Another important idea behind the design of the index is that the
+ultimate goal of deduplication is to reduce storage costs. Since there is a
+trade-off between the storage saved and the resources expended to achieve
+those savings, vdo does not attempt to find every last duplicate block. It
+is sufficient to find and eliminate most of the redundancy.
+
+Each block of data is hashed to produce a 16-byte block name. An index
+record consists of this block name paired with the presumed location of
+that data on the underlying storage. However, it is not possible to
+guarantee that the index is accurate. In the most common case, this occurs
+because it is too costly to update the index when a block is over-written
+or discarded. Doing so would require either storing the block name along
+with the blocks, which is difficult to do efficiently in block-based
+storage, or reading and rehashing each block before overwriting it.
+Inaccuracy can also result from a hash collision where two different blocks
+have the same name. In practice, this is extremely unlikely, but because
+vdo does not use a cryptographic hash, a malicious workload could be
+constructed. Because of these inaccuracies, vdo treats the locations in the
+index as hints, and reads each indicated block to verify that it is indeed
+a duplicate before sharing the existing block with a new one.
+
+Records are collected into groups called chapters. New records are added to
+the newest chapter, called the open chapter. This chapter is stored in a
+format optimized for adding and modifying records, and the content of the
+open chapter is not finalized until it runs out of space for new records.
+When the open chapter fills up, it is closed and a new open chapter is
+created to collect new records.
+
+Closing a chapter converts it to a different format which is optimized for
+reading. The records are written to a series of record pages based on the
+order in which they were received. This means that records with temporal
+locality should be on a small number of pages, reducing the I/O required to
+retrieve them. The chapter also compiles an index that indicates which
+record page contains any given name. This index means that a request for a
+name can determine exactly which record page may contain that record,
+without having to load the entire chapter from storage. This index uses
+only a subset of the block name as its key, so it cannot guarantee that an
+index entry refers to the desired block name. It can only guarantee that if
+there is a record for this name, it will be on the indicated page. Closed
+chapters are read-only structures and their contents are never altered in
+any way.
+
+Once enough records have been written to fill up all the available index
+space, the oldest chapter is removed to make space for new chapters. Any
+time a request finds a matching record in the index, that record is copied
+into the open chapter. This ensures that useful block names remain available
+in the index, while unreferenced block names are forgotten over time.
+
+In order to find records in older chapters, the index also maintains a
+higher level structure called the volume index, which contains entries
+mapping each block name to the chapter containing its newest record. This
+mapping is updated as records for the block name are copied or updated,
+ensuring that only the newest record for a given block name can be found.
+An older record for a block name will no longer be found even though it has
+not been deleted from its chapter. Like the chapter index, the volume index
+uses only a subset of the block name as its key and can not definitively
+say that a record exists for a name. It can only say which chapter would
+contain the record if a record exists. The volume index is stored entirely
+in memory and is saved to storage only when the vdo target is shut down.
+
+From the viewpoint of a request for a particular block name, it will first
+look up the name in the volume index. This search will either indicate that
+the name is new, or which chapter to search. If it returns a chapter, the
+request looks up its name in the chapter index. This will indicate either
+that the name is new, or which record page to search. Finally, if it is not
+new, the request will look for its name in the indicated record page.
+This process may require up to two page reads per request (one for the
+chapter index page and one for the request page). However, recently
+accessed pages are cached so that these page reads can be amortized across
+many block name requests.
+
+The volume index and the chapter indexes are implemented using a
+memory-efficient structure called a delta index. Instead of storing the
+entire block name (the key) for each entry, the entries are sorted by name
+and only the difference between adjacent keys (the delta) is stored.
+Because we expect the hashes to be randomly distributed, the size of the
+deltas follows an exponential distribution. Because of this distribution,
+the deltas are expressed using a Huffman code to take up even less space.
+The entire sorted list of keys is called a delta list. This structure
+allows the index to use many fewer bytes per entry than a traditional hash
+table, but it is slightly more expensive to look up entries, because a
+request must read every entry in a delta list to add up the deltas in order
+to find the record it needs. The delta index reduces this lookup cost by
+splitting its key space into many sub-lists, each starting at a fixed key
+value, so that each individual list is short.
+
+The default index size can hold 64 million records, corresponding to about
+256GB of data. This means that the index can identify duplicate data if the
+original data was written within the last 256GB of writes. This range is
+called the deduplication window. If new writes duplicate data that is older
+than that, the index will not be able to find it because the records of the
+older data have been removed. This means that if an application writes a
+200 GB file to a vdo target and then immediately writes it again, the two
+copies will deduplicate perfectly. Doing the same with a 500 GB file will
+result in no deduplication, because the beginning of the file will no
+longer be in the index by the time the second write begins (assuming there
+is no duplication within the file itself).
+
+If an application anticipates a data workload that will see useful
+deduplication beyond the 256GB threshold, vdo can be configured to use a
+larger index with a correspondingly larger deduplication window. (This
+configuration can only be set when the target is created, not altered
+later. It is important to consider the expected workload for a vdo target
+before configuring it.)  There are two ways to do this.
+
+One way is to increase the memory size of the index, which also increases
+the amount of backing storage required. Doubling the size of the index will
+double the length of the deduplication window at the expense of doubling
+the storage size and the memory requirements.
+
+The other option is to enable sparse indexing. Sparse indexing increases
+the deduplication window by a factor of 10, at the expense of also
+increasing the storage size by a factor of 10. However with sparse
+indexing, the memory requirements do not increase. The trade-off is
+slightly more computation per request and a slight decrease in the amount
+of deduplication detected. For most workloads with significant amounts of
+duplicate data, sparse indexing will detect 97-99% of the deduplication
+that a standard index will detect.
+
+The vio and data_vio Structures
+-------------------------------
+
+A vio (short for Vdo I/O) is conceptually similar to a bio, with additional
+fields and data to track vdo-specific information. A struct vio maintains a
+pointer to a bio but also tracks other fields specific to the operation of
+vdo. The vio is kept separate from its related bio because there are many
+circumstances where vdo completes the bio but must continue to do work
+related to deduplication or compression.
+
+Metadata reads and writes, and other writes that originate within vdo, use
+a struct vio directly. Application reads and writes use a larger structure
+called a data_vio to track information about their progress. A struct
+data_vio contain a struct vio and also includes several other fields
+related to deduplication and other vdo features. The data_vio is the
+primary unit of application work in vdo. Each data_vio proceeds through a
+set of steps to handle the application data, after which it is reset and
+returned to a pool of data_vios for reuse.
+
+There is a fixed pool of 2048 data_vios. This number was chosen to bound
+the amount of work that is required to recover from a crash. In addition,
+benchmarks have indicated that increasing the size of the pool does not
+significantly improve performance.
+
+The Data Store
+--------------
+
+The data store is implemented by three main data structures, all of which
+work in concert to reduce or amortize metadata updates across as many data
+writes as possible.
+
+*The Slab Depot*
+
+Most of the vdo volume belongs to the slab depot. The depot contains a
+collection of slabs. The slabs can be up to 32GB, and are divided into
+three sections. Most of a slab consists of a linear sequence of 4K blocks.
+These blocks are used either to store data, or to hold portions of the
+block map (see below). In addition to the data blocks, each slab has a set
+of reference counters, using 1 byte for each data block. Finally each slab
+has a journal.
+
+Reference updates are written to the slab journal. Slab journal blocks are
+written out either when they are full, or when the recovery journal
+requests they do so in order to allow the main recovery journal (see below)
+to free up space. The slab journal is used both to ensure that the main
+recovery journal can regularly free up space, and also to amortize the cost
+of updating individual reference blocks. The reference counters are kept in
+memory and are written out, a block at a time in oldest-dirtied-order, only
+when there is a need to reclaim slab journal space. The write operations
+are performed in the background as needed so they do not add latency to
+particular I/O operations.
+
+Each slab is independent of every other. They are assigned to "physical
+zones" in round-robin fashion. If there are P physical zones, then slab n
+is assigned to zone n mod P.
+
+The slab depot maintains an additional small data structure, the "slab
+summary," which is used to reduce the amount of work needed to come back
+online after a crash. The slab summary maintains an entry for each slab
+indicating whether or not the slab has ever been used, whether all of its
+reference count updates have been persisted to storage, and approximately
+how full it is. During recovery, each physical zone will attempt to recover
+at least one slab, stopping whenever it has recovered a slab which has some
+free blocks. Once each zone has some space, or has determined that none is
+available, the target can resume normal operation in a degraded mode. Read
+and write requests can be serviced, perhaps with degraded performance,
+while the remainder of the dirty slabs are recovered.
+
+*The Block Map*
+
+The block map contains the logical to physical mapping. It can be thought
+of as an array with one entry per logical address. Each entry is 5 bytes,
+36 bits of which contain the physical block number which holds the data for
+the given logical address. The other 4 bits are used to indicate the nature
+of the mapping. Of the 16 possible states, one represents a logical address
+which is unmapped (i.e. it has never been written, or has been discarded),
+one represents an uncompressed block, and the other 14 states are used to
+indicate that the mapped data is compressed, and which of the compression
+slots in the compressed block contains the data for this logical address.
+
+In practice, the array of mapping entries is divided into "block map
+pages," each of which fits in a single 4K block. Each block map page
+consists of a header and 812 mapping entries. Each mapping page is actually
+a leaf of a radix tree which consists of block map pages at each level.
+There are 60 radix trees which are assigned to "logical zones" in round
+robin fashion. (If there are L logical zones, tree n will belong to zone n
+mod L.) At each level, the trees are interleaved, so logical addresses
+0-811 belong to tree 0, logical addresses 812-1623 belong to tree 1, and so
+on. The interleaving is maintained all the way up to the 60 root nodes.
+Choosing 60 trees results in an evenly distributed number of trees per zone
+for a large number of possible logical zone counts. The storage for the 60
+tree roots is allocated at format time. All other block map pages are
+allocated out of the slabs as needed. This flexible allocation avoids the
+need to pre-allocate space for the entire set of logical mappings and also
+makes growing the logical size of a vdo relatively easy.
+
+In operation, the block map maintains two caches. It is prohibitive to keep
+the entire leaf level of the trees in memory, so each logical zone
+maintains its own cache of leaf pages. The size of this cache is
+configurable at target start time. The second cache is allocated at start
+time, and is large enough to hold all the non-leaf pages of the entire
+block map. This cache is populated as pages are needed.
+
+*The Recovery Journal*
+
+The recovery journal is used to amortize updates across the block map and
+slab depot. Each write request causes an entry to be made in the journal.
+Entries are either "data remappings" or "block map remappings." For a data
+remapping, the journal records the logical address affected and its old and
+new physical mappings. For a block map remapping, the journal records the
+block map page number and the physical block allocated for it. Block map
+pages are never reclaimed or repurposed, so the old mapping is always 0.
+
+Each journal entry is an intent record summarizing the metadata updates
+that are required for a data_vio. The recovery journal issues a flush
+before each journal block write to ensure that the physical data for the
+new block mappings in that block are stable on storage, and journal block
+writes are all issued with the FUA bit set to ensure the recovery journal
+entries themselves are stable. The journal entry and the data write it
+represents must be stable on disk before the other metadata structures may
+be updated to reflect the operation. These entries allow the vdo device to
+reconstruct the logical to physical mappings after an unexpected
+interruption such as a loss of power.
+
+*Write Path*
+
+All write I/O to vdo is asynchronous. Each bio will be acknowledged as soon
+as vdo has done enough work to guarantee that it can complete the write
+eventually. Generally, the data for acknowledged but unflushed write I/O
+can be treated as though it is cached in memory. If an application
+requires data to be stable on storage, it must issue a flush or write the
+data with the FUA bit set like any other asynchronous I/O. Shutting down
+the vdo target will also flush any remaining I/O.
+
+Application write bios follow the steps outlined below.
+
+1.  A data_vio is obtained from the data_vio pool and associated with the
+    application bio. If there are no data_vios available, the incoming bio
+    will block until a data_vio is available. This provides back pressure
+    to the application. The data_vio pool is protected by a spin lock.
+
+    The newly acquired data_vio is reset and the bio's data is copied into
+    the data_vio if it is a write and the data is not all zeroes. The data
+    must be copied because the application bio can be acknowledged before
+    the data_vio processing is complete, which means later processing steps
+    will no longer have access to the application bio. The application bio
+    may also be smaller than 4K, in which case the data_vio will have
+    already read the underlying block and the data is instead copied over
+    the relevant portion of the larger block.
+
+2.  The data_vio places a claim (the "logical lock") on the logical address
+    of the bio. It is vital to prevent simultaneous modifications of the
+    same logical address, because deduplication involves sharing blocks.
+    This claim is implemented as an entry in a hashtable where the key is
+    the logical address and the value is a pointer to the data_vio
+    currently handling that address.
+
+    If a data_vio looks in the hashtable and finds that another data_vio is
+    already operating on that logical address, it waits until the previous
+    operation finishes. It also sends a message to inform the current
+    lock holder that it is waiting. Most notably, a new data_vio waiting
+    for a logical lock will flush the previous lock holder out of the
+    compression packer (step 8d) rather than allowing it to continue
+    waiting to be packed.
+
+    This stage requires the data_vio to get an implicit lock on the
+    appropriate logical zone to prevent concurrent modifications of the
+    hashtable. This implicit locking is handled by the zone divisions
+    described above.
+
+3.  The data_vio traverses the block map tree to ensure that all the
+    necessary internal tree nodes have been allocated, by trying to find
+    the leaf page for its logical address. If any interior tree page is
+    missing, it is allocated at this time out of the same physical storage
+    pool used to store application data.
+
+    a. If any page-node in the tree has not yet been allocated, it must be
+       allocated before the write can continue. This step requires the
+       data_vio to lock the page-node that needs to be allocated. This
+       lock, like the logical block lock in step 2, is a hashtable entry
+       that causes other data_vios to wait for the allocation process to
+       complete.
+
+       The implicit logical zone lock is released while the allocation is
+       happening, in order to allow other operations in the same logical
+       zone to proceed. The details of allocation are the same as in
+       step 4. Once a new node has been allocated, that node is added to
+       the tree using a similar process to adding a new data block mapping.
+       The data_vio journals the intent to add the new node to the block
+       map tree (step 10), updates the reference count of the new block
+       (step 11), and reacquires the implicit logical zone lock to add the
+       new mapping to the parent tree node (step 12). Once the tree is
+       updated, the data_vio proceeds down the tree. Any other data_vios
+       waiting on this allocation also proceed.
+
+    b. In the steady-state case, the block map tree nodes will already be
+       allocated, so the data_vio just traverses the tree until it finds
+       the required leaf node. The location of the mapping (the "block map
+       slot") is recorded in the data_vio so that later steps do not need
+       to traverse the tree again. The data_vio then releases the implicit
+       logical zone lock.
+
+4.  If the block is a zero block, skip to step 9. Otherwise, an attempt is
+    made to allocate a free data block. This allocation ensures that the
+    data_vio can write its data somewhere even if deduplication and
+    compression are not possible. This stage gets an implicit lock on a
+    physical zone to search for free space within that zone.
+
+    The data_vio will search each slab in a zone until it finds a free
+    block or decides there are none. If the first zone has no free space,
+    it will proceed to search the next physical zone by taking the implicit
+    lock for that zone and releasing the previous one until it finds a
+    free block or runs out of zones to search. The data_vio will acquire a
+    struct pbn_lock (the "physical block lock") on the free block. The
+    struct pbn_lock also has several fields to record the various kinds of
+    claims that data_vios can have on physical blocks. The pbn_lock is
+    added to a hashtable like the logical block locks in step 2. This
+    hashtable is also covered by the implicit physical zone lock. The
+    reference count of the free block is updated to prevent any other
+    data_vio from considering it free. The reference counters are a
+    sub-component of the slab and are thus also covered by the implicit
+    physical zone lock.
+
+5.  If an allocation was obtained, the data_vio has all the resources it
+    needs to complete the write. The application bio can safely be
+    acknowledged at this point. The acknowledgment happens on a separate
+    thread to prevent the application callback from blocking other data_vio
+    operations.
+
+    If an allocation could not be obtained, the data_vio continues to
+    attempt to deduplicate or compress the data, but the bio is not
+    acknowledged because the vdo device may be out of space.
+
+6.  At this point vdo must determine where to store the application data.
+    The data_vio's data is hashed and the hash (the "record name") is
+    recorded in the data_vio.
+
+7.  The data_vio reserves or joins a struct hash_lock, which manages all of
+    the data_vios currently writing the same data. Active hash locks are
+    tracked in a hashtable similar to the way logical block locks are
+    tracked in step 2. This hashtable is covered by the implicit lock on
+    the hash zone.
+
+    If there is no existing hash lock for this data_vio's record_name, the
+    data_vio obtains a hash lock from the pool, adds it to the hashtable,
+    and sets itself as the new hash lock's "agent." The hash_lock pool is
+    also covered by the implicit hash zone lock. The hash lock agent will
+    do all the work to decide where the application data will be
+    written. If a hash lock for the data_vio's record_name already exists,
+    and the data_vio's data is the same as the agent's data, the new
+    data_vio will wait for the agent to complete its work and then share
+    its result.
+
+    In the rare case that a hash lock exists for the data_vio's hash but
+    the data does not match the hash lock's agent, the data_vio skips to
+    step 8h and attempts to write its data directly. This can happen if two
+    different data blocks produce the same hash, for example.
+
+8.  The hash lock agent attempts to deduplicate or compress its data with
+    the following steps.
+
+    a. The agent initializes and sends its embedded deduplication request
+       (struct uds_request) to the deduplication index. This does not
+       require the data_vio to get any locks because the index components
+       manage their own locking. The data_vio waits until it either gets a
+       response from the index or times out.
+
+    b. If the deduplication index returns advice, the data_vio attempts to
+       obtain a physical block lock on the indicated physical address, in
+       order to read the data and verify that it is the same as the
+       data_vio's data, and that it can accept more references. If the
+       physical address is already locked by another data_vio, the data at
+       that address may soon be overwritten so it is not safe to use the
+       address for deduplication.
+
+    c. If the data matches and the physical block can add references, the
+       agent and any other data_vios waiting on it will record this
+       physical block as their new physical address and proceed to step 9
+       to record their new mapping. If there are more data_vios in the hash
+       lock than there are references available, one of the remaining
+       data_vios becomes the new agent and continues to step 8d as if no
+       valid advice was returned.
+
+    d. If no usable duplicate block was found, the agent first checks that
+       it has an allocated physical block (from step 3) that it can write
+       to. If the agent does not have an allocation, some other data_vio in
+       the hash lock that does have an allocation takes over as agent. If
+       none of the data_vios have an allocated physical block, these writes
+       are out of space, so they proceed to step 13 for cleanup.
+
+    e. The agent attempts to compress its data. If the data does not
+       compress, the data_vio will continue to step 8h to write its data
+       directly.
+
+       If the compressed size is small enough, the agent will release the
+       implicit hash zone lock and go to the packer (struct packer) where
+       it will be placed in a bin (struct packer_bin) along with other
+       data_vios. All compression operations require the implicit lock on
+       the packer zone.
+
+       The packer can combine up to 14 compressed blocks in a single 4k
+       data block. Compression is only helpful if vdo can pack at least 2
+       data_vios into a single data block. This means that a data_vio may
+       wait in the packer for an arbitrarily long time for other data_vios
+       to fill out the compressed block. There is a mechanism for vdo to
+       evict waiting data_vios when continuing to wait would cause
+       problems. Circumstances causing an eviction include an application
+       flush, device shutdown, or a subsequent data_vio trying to overwrite
+       the same logical block address. A data_vio may also be evicted from
+       the packer if it cannot be paired with any other compressed block
+       before more compressible blocks need to use its bin. An evicted
+       data_vio will proceed to step 8h to write its data directly.
+
+    f. If the agent fills a packer bin, either because all 14 of its slots
+       are used or because it has no remaining space, it is written out
+       using the allocated physical block from one of its data_vios. Step
+       8d has already ensured that an allocation is available.
+
+    g. Each data_vio sets the compressed block as its new physical address.
+       The data_vio obtains an implicit lock on the physical zone and
+       acquires the struct pbn_lock for the compressed block, which is
+       modified to be a shared lock. Then it releases the implicit physical
+       zone lock and proceeds to step 8i.
+
+    h. Any data_vio evicted from the packer will have an allocation from
+       step 3. It will write its data to that allocated physical block.
+
+    i. After the data is written, if the data_vio is the agent of a hash
+       lock, it will reacquire the implicit hash zone lock and share its
+       physical address with as many other data_vios in the hash lock as
+       possible. Each data_vio will then proceed to step 9 to record its
+       new mapping.
+
+    j. If the agent actually wrote new data (whether compressed or not),
+       the deduplication index is updated to reflect the location of the
+       new data. The agent then releases the implicit hash zone lock.
+
+9.  The data_vio determines the previous mapping of the logical address.
+    There is a cache for block map leaf pages (the "block map cache"),
+    because there are usually too many block map leaf nodes to store
+    entirely in memory. If the desired leaf page is not in the cache, the
+    data_vio will reserve a slot in the cache and load the desired page
+    into it, possibly evicting an older cached page. The data_vio then
+    finds the current physical address for this logical address (the "old
+    physical mapping"), if any, and records it. This step requires a lock
+    on the block map cache structures, covered by the implicit logical zone
+    lock.
+
+10. The data_vio makes an entry in the recovery journal containing the
+    logical block address, the old physical mapping, and the new physical
+    mapping. Making this journal entry requires holding the implicit
+    recovery journal lock. The data_vio will wait in the journal until all
+    recovery blocks up to the one containing its entry have been written
+    and flushed to ensure the transaction is stable on storage.
+
+11. Once the recovery journal entry is stable, the data_vio makes two slab
+    journal entries: an increment entry for the new mapping, and a
+    decrement entry for the old mapping. These two operations each require
+    holding a lock on the affected physical slab, covered by its implicit
+    physical zone lock. For correctness during recovery, the slab journal
+    entries in any given slab journal must be in the same order as the
+    corresponding recovery journal entries. Therefore, if the two entries
+    are in different zones, they are made concurrently, and if they are in
+    the same zone, the increment is always made before the decrement in
+    order to avoid underflow. After each slab journal entry is made in
+    memory, the associated reference count is also updated in memory.
+
+12. Once both of the reference count updates are done, the data_vio
+    acquires the implicit logical zone lock and updates the
+    logical-to-physical mapping in the block map to point to the new
+    physical block. At this point the write operation is complete.
+
+13. If the data_vio has a hash lock, it acquires the implicit hash zone
+    lock and releases its hash lock to the pool.
+
+    The data_vio then acquires the implicit physical zone lock and releases
+    the struct pbn_lock it holds for its allocated block. If it had an
+    allocation that it did not use, it also sets the reference count for
+    that block back to zero to free it for use by subsequent data_vios.
+
+    The data_vio then acquires the implicit logical zone lock and releases
+    the logical block lock acquired in step 2.
+
+    The application bio is then acknowledged if it has not previously been
+    acknowledged, and the data_vio is returned to the pool.
+
+*Read Path*
+
+An application read bio follows a much simpler set of steps. It does steps
+1 and 2 in the write path to obtain a data_vio and lock its logical
+address. If there is already a write data_vio in progress for that logical
+address that is guaranteed to complete, the read data_vio will copy the
+data from the write data_vio and return it. Otherwise, it will look up the
+logical-to-physical mapping by traversing the block map tree as in step 3,
+and then read and possibly decompress the indicated data at the indicated
+physical block address. A read data_vio will not allocate block map tree
+nodes if they are missing. If the interior block map nodes do not exist
+yet, the logical block map address must still be unmapped and the read
+data_vio will return all zeroes. A read data_vio handles cleanup and
+acknowledgment as in step 13, although it only needs to release the logical
+lock and return itself to the pool.
+
+*Small Writes*
+
+All storage within vdo is managed as 4KB blocks, but it can accept writes
+as small as 512 bytes. Processing a write that is smaller than 4K requires
+a read-modify-write operation that reads the relevant 4K block, copies the
+new data over the appropriate sectors of the block, and then launches a
+write operation for the modified data block. The read and write stages of
+this operation are nearly identical to the normal read and write
+operations, and a single data_vio is used throughout this operation.
+
+*Recovery*
+
+When a vdo is restarted after a crash, it will attempt to recover from the
+recovery journal. During the pre-resume phase of the next start, the
+recovery journal is read. The increment portion of valid entries are played
+into the block map. Next, valid entries are played, in order as required,
+into the slab journals. Finally, each physical zone attempts to replay at
+least one slab journal to reconstruct the reference counts of one slab.
+Once each zone has some free space (or has determined that it has none),
+the vdo comes back online, while the remainder of the slab journals are
+used to reconstruct the rest of the reference counts in the background.
+
+*Read-only Rebuild*
+
+If a vdo encounters an unrecoverable error, it will enter read-only mode.
+This mode indicates that some previously acknowledged data may have been
+lost. The vdo may be instructed to rebuild as best it can in order to
+return to a writable state. However, this is never done automatically due
+to the possibility that data has been lost. During a read-only rebuild, the
+block map is recovered from the recovery journal as before. However, the
+reference counts are not rebuilt from the slab journals. Instead, the
+reference counts are zeroed, the entire block map is traversed, and the
+reference counts are updated from the block mappings. While this may lose
+some data, it ensures that the block map and reference counts are
+consistent with each other. This allows vdo to resume normal operation and
+accept further writes.
diff --git a/Documentation/admin-guide/device-mapper/vdo.rst b/Documentation/admin-guide/device-mapper/vdo.rst
new file mode 100644
index 000000000..8a67b320a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/vdo.rst
@@ -0,0 +1,413 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+======
+dm-vdo
+======
+
+The dm-vdo (virtual data optimizer) device mapper target provides
+block-level deduplication, compression, and thin provisioning. As a device
+mapper target, it can add these features to the storage stack, compatible
+with any file system. The vdo target does not protect against data
+corruption, relying instead on integrity protection of the storage below
+it. It is strongly recommended that lvm be used to manage vdo volumes. See
+lvmvdo(7).
+
+Userspace component
+===================
+
+Formatting a vdo volume requires the use of the 'vdoformat' tool, available
+at:
+
+https://github.com/dm-vdo/vdo/
+
+In most cases, a vdo target will recover from a crash automatically the
+next time it is started. In cases where it encountered an unrecoverable
+error (either during normal operation or crash recovery) the target will
+enter or come up in read-only mode. Because read-only mode is indicative of
+data-loss, a positive action must be taken to bring vdo out of read-only
+mode. The 'vdoforcerebuild' tool, available from the same repo, is used to
+prepare a read-only vdo to exit read-only mode. After running this tool,
+the vdo target will rebuild its metadata the next time it is
+started. Although some data may be lost, the rebuilt vdo's metadata will be
+internally consistent and the target will be writable again.
+
+The repo also contains additional userspace tools which can be used to
+inspect a vdo target's on-disk metadata. Fortunately, these tools are
+rarely needed except by dm-vdo developers.
+
+Metadata requirements
+=====================
+
+Each vdo volume reserves 3GB of space for metadata, or more depending on
+its configuration. It is helpful to check that the space saved by
+deduplication and compression is not cancelled out by the metadata
+requirements. An estimation of the space saved for a specific dataset can
+be computed with the vdo estimator tool, which is available at:
+
+https://github.com/dm-vdo/vdoestimator/
+
+Target interface
+================
+
+Table line
+----------
+
+::
+
+	<offset> <logical device size> vdo V4 <storage device>
+	<storage device size> <minimum I/O size> <block map cache size>
+	<block map era length> [optional arguments]
+
+
+Required parameters:
+
+	offset:
+		The offset, in sectors, at which the vdo volume's logical
+		space begins.
+
+	logical device size:
+		The size of the device which the vdo volume will service,
+		in sectors. Must match the current logical size of the vdo
+		volume.
+
+	storage device:
+		The device holding the vdo volume's data and metadata.
+
+	storage device size:
+		The size of the device holding the vdo volume, as a number
+		of 4096-byte blocks. Must match the current size of the vdo
+		volume.
+
+	minimum I/O size:
+		The minimum I/O size for this vdo volume to accept, in
+		bytes. Valid values are 512 or 4096. The recommended value
+		is 4096.
+
+	block map cache size:
+		The size of the block map cache, as a number of 4096-byte
+		blocks. The minimum and recommended value is 32768 blocks.
+		If the logical thread count is non-zero, the cache size
+		must be at least 4096 blocks per logical thread.
+
+	block map era length:
+		The speed with which the block map cache writes out
+		modified block map pages. A smaller era length is likely to
+		reduce the amount of time spent rebuilding, at the cost of
+		increased block map writes during normal operation. The
+		maximum and recommended value is 16380; the minimum value
+		is 1.
+
+Optional parameters:
+--------------------
+Some or all of these parameters may be specified as <key> <value> pairs.
+
+Thread related parameters:
+
+Different categories of work are assigned to separate thread groups, and
+the number of threads in each group can be configured separately.
+
+If <hash>, <logical>, and <physical> are all set to 0, the work handled by
+all three thread types will be handled by a single thread. If any of these
+values are non-zero, all of them must be non-zero.
+
+	ack:
+		The number of threads used to complete bios. Since
+		completing a bio calls an arbitrary completion function
+		outside the vdo volume, threads of this type allow the vdo
+		volume to continue processing requests even when bio
+		completion is slow. The default is 1.
+
+	bio:
+		The number of threads used to issue bios to the underlying
+		storage. Threads of this type allow the vdo volume to
+		continue processing requests even when bio submission is
+		slow. The default is 4.
+
+	bioRotationInterval:
+		The number of bios to enqueue on each bio thread before
+		switching to the next thread. The value must be greater
+		than 0 and not more than 1024; the default is 64.
+
+	cpu:
+		The number of threads used to do CPU-intensive work, such
+		as hashing and compression. The default is 1.
+
+	hash:
+		The number of threads used to manage data comparisons for
+		deduplication based on the hash value of data blocks. The
+		default is 0.
+
+	logical:
+		The number of threads used to manage caching and locking
+		based on the logical address of incoming bios. The default
+		is 0; the maximum is 60.
+
+	physical:
+		The number of threads used to manage administration of the
+		underlying storage device. At format time, a slab size for
+		the vdo is chosen; the vdo storage device must be large
+		enough to have at least 1 slab per physical thread. The
+		default is 0; the maximum is 16.
+
+Miscellaneous parameters:
+
+	maxDiscard:
+		The maximum size of discard bio accepted, in 4096-byte
+		blocks. I/O requests to a vdo volume are normally split
+		into 4096-byte blocks, and processed up to 2048 at a time.
+		However, discard requests to a vdo volume can be
+		automatically split to a larger size, up to <maxDiscard>
+		4096-byte blocks in a single bio, and are limited to 1500
+		at a time. Increasing this value may provide better overall
+		performance, at the cost of increased latency for the
+		individual discard requests. The default and minimum is 1;
+		the maximum is UINT_MAX / 4096.
+
+	deduplication:
+		Whether deduplication is enabled. The default is 'on'; the
+		acceptable values are 'on' and 'off'.
+
+	compression:
+		Whether compression is enabled. The default is 'off'; the
+		acceptable values are 'on' and 'off'.
+
+Device modification
+-------------------
+
+A modified table may be loaded into a running, non-suspended vdo volume.
+The modifications will take effect when the device is next resumed. The
+modifiable parameters are <logical device size>, <physical device size>,
+<maxDiscard>, <compression>, and <deduplication>.
+
+If the logical device size or physical device size are changed, upon
+successful resume vdo will store the new values and require them on future
+startups. These two parameters may not be decreased. The logical device
+size may not exceed 4 PB. The physical device size must increase by at
+least 32832 4096-byte blocks if at all, and must not exceed the size of the
+underlying storage device. Additionally, when formatting the vdo device, a
+slab size is chosen: the physical device size may never increase above the
+size which provides 8192 slabs, and each increase must be large enough to
+add at least one new slab.
+
+Examples:
+
+Start a previously-formatted vdo volume with 1 GB logical space and 1 GB
+physical space, storing to /dev/dm-1 which has more than 1 GB of space.
+
+::
+
+	dmsetup create vdo0 --table \
+	"0 2097152 vdo V4 /dev/dm-1 262144 4096 32768 16380"
+
+Grow the logical size to 4 GB.
+
+::
+
+	dmsetup reload vdo0 --table \
+	"0 8388608 vdo V4 /dev/dm-1 262144 4096 32768 16380"
+	dmsetup resume vdo0
+
+Grow the physical size to 2 GB.
+
+::
+
+	dmsetup reload vdo0 --table \
+	"0 8388608 vdo V4 /dev/dm-1 524288 4096 32768 16380"
+	dmsetup resume vdo0
+
+Grow the physical size by 1 GB more and increase max discard sectors.
+
+::
+
+	dmsetup reload vdo0 --table \
+	"0 10485760 vdo V4 /dev/dm-1 786432 4096 32768 16380 maxDiscard 8"
+	dmsetup resume vdo0
+
+Stop the vdo volume.
+
+::
+
+	dmsetup remove vdo0
+
+Start the vdo volume again. Note that the logical and physical device sizes
+must still match, but other parameters can change.
+
+::
+
+	dmsetup create vdo1 --table \
+	"0 10485760 vdo V4 /dev/dm-1 786432 512 65550 5000 hash 1 logical 3 physical 2"
+
+Messages
+--------
+All vdo devices accept messages in the form:
+
+::
+
+        dmsetup message <target-name> 0 <message-name> <message-parameters>
+
+The messages are:
+
+        stats:
+		Outputs the current view of the vdo statistics. Mostly used
+		by the vdostats userspace program to interpret the output
+		buffer.
+
+	config:
+		Outputs useful vdo configuration information. Mostly used
+		by users who want to recreate a similar VDO volume and
+		want to know the creation configuration used.
+
+	dump:
+		Dumps many internal structures to the system log. This is
+		not always safe to run, so it should only be used to debug
+		a hung vdo. Optional parameters to specify structures to
+		dump are:
+
+			viopool: The pool of I/O requests incoming bios
+			pools: A synonym of 'viopool'
+			vdo: Most of the structures managing on-disk data
+			queues: Basic information about each vdo thread
+			threads: A synonym of 'queues'
+			default: Equivalent to 'queues vdo'
+			all: All of the above.
+
+        dump-on-shutdown:
+		Perform a default dump next time vdo shuts down.
+
+
+Status
+------
+
+::
+
+    <device> <operating mode> <in recovery> <index state>
+    <compression state> <physical blocks used> <total physical blocks>
+
+	device:
+		The name of the vdo volume.
+
+	operating mode:
+		The current operating mode of the vdo volume; values may be
+		'normal', 'recovering' (the volume has detected an issue
+		with its metadata and is attempting to repair itself), and
+		'read-only' (an error has occurred that forces the vdo
+		volume to only support read operations and not writes).
+
+	in recovery:
+		Whether the vdo volume is currently in recovery mode;
+		values may be 'recovering' or '-' which indicates not
+		recovering.
+
+	index state:
+		The current state of the deduplication index in the vdo
+		volume; values may be 'closed', 'closing', 'error',
+		'offline', 'online', 'opening', and 'unknown'.
+
+	compression state:
+		The current state of compression in the vdo volume; values
+		may be 'offline' and 'online'.
+
+	used physical blocks:
+		The number of physical blocks in use by the vdo volume.
+
+	total physical blocks:
+		The total number of physical blocks the vdo volume may use;
+		the difference between this value and the
+		<used physical blocks> is the number of blocks the vdo
+		volume has left before being full.
+
+Memory Requirements
+===================
+
+A vdo target requires a fixed 38 MB of RAM along with the following amounts
+that scale with the target:
+
+- 1.15 MB of RAM for each 1 MB of configured block map cache size. The
+  block map cache requires a minimum of 150 MB.
+- 1.6 MB of RAM for each 1 TB of logical space.
+- 268 MB of RAM for each 1 TB of physical storage managed by the volume.
+
+The deduplication index requires additional memory which scales with the
+size of the deduplication window. For dense indexes, the index requires 1
+GB of RAM per 1 TB of window. For sparse indexes, the index requires 1 GB
+of RAM per 10 TB of window. The index configuration is set when the target
+is formatted and may not be modified.
+
+Module Parameters
+=================
+
+The vdo driver has a numeric parameter 'log_level' which controls the
+verbosity of logging from the driver. The default setting is 6
+(LOGLEVEL_INFO and more severe messages).
+
+Run-time Usage
+==============
+
+When using dm-vdo, it is important to be aware of the ways in which its
+behavior differs from other storage targets.
+
+- There is no guarantee that over-writes of existing blocks will succeed.
+  Because the underlying storage may be multiply referenced, over-writing
+  an existing block generally requires a vdo to have a free block
+  available.
+
+- When blocks are no longer in use, sending a discard request for those
+  blocks lets the vdo release references for those blocks. If the vdo is
+  thinly provisioned, discarding unused blocks is essential to prevent the
+  target from running out of space. However, due to the sharing of
+  duplicate blocks, no discard request for any given logical block is
+  guaranteed to reclaim space.
+
+- Assuming the underlying storage properly implements flush requests, vdo
+  is resilient against crashes, however, unflushed writes may or may not
+  persist after a crash.
+
+- Each write to a vdo target entails a significant amount of processing.
+  However, much of the work is paralellizable. Therefore, vdo targets
+  achieve better throughput at higher I/O depths, and can support up 2048
+  requests in parallel.
+
+Tuning
+======
+
+The vdo device has many options, and it can be difficult to make optimal
+choices without perfect knowledge of the workload. Additionally, most
+configuration options must be set when a vdo target is started, and cannot
+be changed without shutting it down completely; the configuration cannot be
+changed while the target is active. Ideally, tuning with simulated
+workloads should be performed before deploying vdo in production
+environments.
+
+The most important value to adjust is the block map cache size. In order to
+service a request for any logical address, a vdo must load the portion of
+the block map which holds the relevant mapping. These mappings are cached.
+Performance will suffer when the working set does not fit in the cache. By
+default, a vdo allocates 128 MB of metadata cache in RAM to support
+efficient access to 100 GB of logical space at a time. It should be scaled
+up proportionally for larger working sets.
+
+The logical and physical thread counts should also be adjusted. A logical
+thread controls a disjoint section of the block map, so additional logical
+threads increase parallelism and can increase throughput. Physical threads
+control a disjoint section of the data blocks, so additional physical
+threads can also increase throughput. However, excess threads can waste
+resources and increase contention.
+
+Bio submission threads control the parallelism involved in sending I/O to
+the underlying storage; fewer threads mean there is more opportunity to
+reorder I/O requests for performance benefit, but also that each I/O
+request has to wait longer before being submitted.
+
+Bio acknowledgment threads are used for finishing I/O requests. This is
+done on dedicated threads since the amount of work required to execute a
+bio's callback can not be controlled by the vdo itself. Usually one thread
+is sufficient but additional threads may be beneficial, particularly when
+bios have CPU-heavy callbacks.
+
+CPU threads are used for hashing and for compression; in workloads with
+compression enabled, more threads may result in higher throughput.
+
+Hash threads are used to sort active requests by hash and determine whether
+they should deduplicate; the most CPU intensive actions done by these
+threads are comparison of 4096-byte data blocks. In most cases, a single
+hash thread is sufficient.
diff --git a/Documentation/admin-guide/device-mapper/verity.rst b/Documentation/admin-guide/device-mapper/verity.rst
new file mode 100644
index 000000000..eb9475d7e
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/verity.rst
@@ -0,0 +1,349 @@
+=========
+dm-verity
+=========
+
+Device-Mapper's "verity" target provides transparent integrity checking of
+block devices using a cryptographic digest provided by the kernel crypto API.
+This target is read-only.
+
+Construction Parameters
+=======================
+
+::
+
+    <version> <dev> <hash_dev>
+    <data_block_size> <hash_block_size>
+    <num_data_blocks> <hash_start_block>
+    <algorithm> <digest> <salt>
+    [<#opt_params> <opt_params>]
+
+<version>
+    This is the type of the on-disk hash format.
+
+    0 is the original format used in the Chromium OS.
+      The salt is appended when hashing, digests are stored continuously and
+      the rest of the block is padded with zeroes.
+
+    1 is the current format that should be used for new devices.
+      The salt is prepended when hashing and each digest is
+      padded with zeroes to the power of two.
+
+<dev>
+    This is the device containing data, the integrity of which needs to be
+    checked.  It may be specified as a path, like /dev/sdaX, or a device number,
+    <major>:<minor>.
+
+<hash_dev>
+    This is the device that supplies the hash tree data.  It may be
+    specified similarly to the device path and may be the same device.  If the
+    same device is used, the hash_start should be outside the configured
+    dm-verity device.
+
+<data_block_size>
+    The block size on a data device in bytes.
+    Each block corresponds to one digest on the hash device.
+
+<hash_block_size>
+    The size of a hash block in bytes.
+
+<num_data_blocks>
+    The number of data blocks on the data device.  Additional blocks are
+    inaccessible.  You can place hashes to the same partition as data, in this
+    case hashes are placed after <num_data_blocks>.
+
+<hash_start_block>
+    This is the offset, in <hash_block_size>-blocks, from the start of hash_dev
+    to the root block of the hash tree.
+
+<algorithm>
+    The cryptographic hash algorithm used for this device.  This should
+    be the name of the algorithm, like "sha1".
+
+<digest>
+    The hexadecimal encoding of the cryptographic hash of the root hash block
+    and the salt.  This hash should be trusted as there is no other authenticity
+    beyond this point.
+
+<salt>
+    The hexadecimal encoding of the salt value.
+
+<#opt_params>
+    Number of optional parameters. If there are no optional parameters,
+    the optional parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        1 ignore_corruption
+
+ignore_corruption
+    Log corrupted blocks, but allow read operations to proceed normally.
+
+restart_on_corruption
+    Restart the system when a corrupted block is discovered. This option is
+    not compatible with ignore_corruption and requires user space support to
+    avoid restart loops.
+
+panic_on_corruption
+    Panic the device when a corrupted block is discovered. This option is
+    not compatible with ignore_corruption and restart_on_corruption.
+
+restart_on_error
+    Restart the system when an I/O error is detected.
+    This option can be combined with the restart_on_corruption option.
+
+panic_on_error
+    Panic the device when an I/O error is detected. This option is
+    not compatible with the restart_on_error option but can be combined
+    with the panic_on_corruption option.
+
+ignore_zero_blocks
+    Do not verify blocks that are expected to contain zeroes and always return
+    zeroes instead. This may be useful if the partition contains unused blocks
+    that are not guaranteed to contain zeroes.
+
+use_fec_from_device <fec_dev>
+    Use forward error correction (FEC) parity data from the specified device to
+    try to automatically recover from corruption and I/O errors.
+
+    If this option is given, then <fec_roots> and <fec_blocks> must also be
+    given.  <hash_block_size> must also be equal to <data_block_size>.
+
+    <fec_dev> can be the same as <dev>, in which case <fec_start> must be
+    outside the data area.  It can also be the same as <hash_dev>, in which case
+    <fec_start> must be outside the hash and optional additional metadata areas.
+
+    If the data <dev> is encrypted, the <fec_dev> should be too.
+
+    For more information, see `Forward error correction`_.
+
+fec_roots <num>
+    The number of parity bytes in each 255-byte Reed-Solomon codeword.  The
+    Reed-Solomon code used will be an RS(255, k) code where k = 255 - fec_roots.
+
+    The supported values are 2 through 24 inclusive.  Higher values provide
+    stronger error correction.  However, the minimum value of 2 already provides
+    strong error correction due to the use of interleaving, so 2 is the
+    recommended value for most users.  fec_roots=2 corresponds to an
+    RS(255, 253) code, which has a space overhead of about 0.8%.
+
+fec_blocks <num>
+    The total number of <data_block_size> blocks that are error-checked using
+    FEC.  This must be at least the sum of <num_data_blocks> and the number of
+    blocks needed by the hash tree.  It can include additional metadata blocks,
+    which are assumed to be accessible on <hash_dev> following the hash blocks.
+
+    Note that this is *not* the number of parity blocks.  The number of parity
+    blocks is inferred from <fec_blocks>, <fec_roots>, and <data_block_size>.
+
+fec_start <offset>
+    This is the offset, in <data_block_size> blocks, from the start of <fec_dev>
+    to the beginning of the parity data.
+
+check_at_most_once
+    Verify data blocks only the first time they are read from the data device,
+    rather than every time.  This reduces the overhead of dm-verity so that it
+    can be used on systems that are memory and/or CPU constrained.  However, it
+    provides a reduced level of security because only offline tampering of the
+    data device's content will be detected, not online tampering.
+
+    Hash blocks are still verified each time they are read from the hash device,
+    since verification of hash blocks is less performance critical than data
+    blocks, and a hash block will not be verified any more after all the data
+    blocks it covers have been verified anyway.
+
+root_hash_sig_key_desc <key_description>
+    This is the description of the USER_KEY that the kernel will lookup to get
+    the pkcs7 signature of the roothash. The pkcs7 signature is used to validate
+    the root hash during the creation of the device mapper block device.
+    Verification of roothash depends on the config DM_VERITY_VERIFY_ROOTHASH_SIG
+    being set in the kernel.  The signatures are checked against the builtin
+    trusted keyring by default, or the secondary trusted keyring if
+    DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING is set.  The secondary
+    trusted keyring includes by default the builtin trusted keyring, and it can
+    also gain new certificates at run time if they are signed by a certificate
+    already in the secondary trusted keyring.
+
+try_verify_in_tasklet
+    If verity hashes are in cache and the IO size does not exceed the limit,
+    verify data blocks in bottom half instead of workqueue. This option can
+    reduce IO latency. The size limits can be configured via
+    /sys/module/dm_verity/parameters/use_bh_bytes. The four parameters
+    correspond to limits for IOPRIO_CLASS_NONE, IOPRIO_CLASS_RT,
+    IOPRIO_CLASS_BE and IOPRIO_CLASS_IDLE in turn.
+    For example:
+    <none>,<rt>,<be>,<idle>
+    4096,4096,4096,4096
+
+Theory of operation
+===================
+
+dm-verity is meant to be set up as part of a verified boot path.  This
+may be anything ranging from a boot using tboot or trustedgrub to just
+booting from a known-good device (like a USB drive or CD).
+
+When a dm-verity device is configured, it is expected that the caller
+has been authenticated in some way (cryptographic signatures, etc).
+After instantiation, all hashes will be verified on-demand during
+disk access.  If they cannot be verified up to the root node of the
+tree, the root hash, then the I/O will fail.  This should detect
+tampering with any data on the device and the hash data.
+
+Cryptographic hashes are used to assert the integrity of the device on a
+per-block basis. This allows for a lightweight hash computation on first read
+into the page cache. Block hashes are stored linearly, aligned to the nearest
+block size.
+
+Hash Tree
+---------
+
+Each node in the tree is a cryptographic hash.  If it is a leaf node, the hash
+of some data block on disk is calculated. If it is an intermediary node,
+the hash of a number of child nodes is calculated.
+
+Each entry in the tree is a collection of neighboring nodes that fit in one
+block.  The number is determined based on block_size and the size of the
+selected cryptographic digest algorithm.  The hashes are linearly-ordered in
+this entry and any unaligned trailing space is ignored but included when
+calculating the parent node.
+
+The tree looks something like:
+
+	alg = sha256, num_blocks = 32768, block_size = 4096
+
+::
+
+                                 [   root    ]
+                                /    . . .    \
+                     [entry_0]                 [entry_1]
+                    /  . . .  \                 . . .   \
+         [entry_0_0]   . . .  [entry_0_127]    . . . .  [entry_1_127]
+           / ... \             /   . . .  \             /           \
+     blk_0 ... blk_127  blk_16256   blk_16383      blk_32640 . . . blk_32767
+
+Forward error correction
+------------------------
+
+dm-verity's optional forward error correction (FEC) support adds strong error
+correction capabilities to dm-verity.  It allows systems that would be rendered
+inoperable by errors to continue operating, albeit with reduced performance.
+
+FEC uses Reed-Solomon (RS) codes that are interleaved across the entire
+device(s), allowing long bursts of corrupt or unreadable blocks to be recovered.
+
+dm-verity validates any FEC-corrected block against the wanted hash before using
+it.  Therefore, FEC doesn't affect the security properties of dm-verity.
+
+The integration of FEC with dm-verity provides significant benefits over a
+separate error correction layer:
+
+- dm-verity invokes FEC only when a block's hash doesn't match the wanted hash
+  or the block cannot be read at all.  As a result, FEC doesn't add overhead to
+  the common case where no error occurs.
+
+- dm-verity hashes are also used to identify erasure locations for RS decoding.
+  This allows correcting twice as many errors.
+
+FEC uses an RS(255, k) code where k = 255 - fec_roots.  fec_roots is usually 2.
+This means that each k (usually 253) message bytes have fec_roots (usually 2)
+bytes of parity data added to get a 255-byte codeword.  (Many external sources
+call RS codewords "blocks".  Since dm-verity already uses the term "block" to
+mean something else, we'll use the clearer term "RS codeword".)
+
+FEC checks fec_blocks blocks of message data in total, consisting of:
+
+1. The data blocks from the data device
+2. The hash blocks from the hash device
+3. Optional additional metadata that follows the hash blocks on the hash device
+
+dm-verity assumes that the FEC parity data was computed as if the following
+procedure were followed:
+
+1. Concatenate the message data from the above sources.
+2. Zero-pad to the next multiple of k blocks.  Let msg be the resulting byte
+   array, and msglen its length in bytes.
+3. For 0 <= i < msglen / k (for each RS codeword):
+     a. Select msg[i + j * msglen / k] for 0 <= j < k.
+        Consider these to be the 'k' message bytes of an RS codeword.
+     b. Compute the corresponding 'fec_roots' parity bytes of the RS codeword,
+        and concatenate them to the FEC parity data.
+
+Step 3a interleaves the RS codewords across the entire device using an
+interleaving degree of data_block_size * ceil(fec_blocks / k).  This is the
+maximal interleaving, such that the message data consists of a region containing
+byte 0 of all the RS codewords, then a region containing byte 1 of all the RS
+codewords, and so on up to the region for byte 'k - 1'.  Note that the number of
+codewords is set to a multiple of data_block_size; thus, the regions are
+block-aligned, and there is an implicit zero padding of up to 'k - 1' blocks.
+
+This interleaving allows long bursts of errors to be corrected.  It provides
+much stronger error correction than storage devices typically provide, while
+keeping the space overhead low.
+
+The cost is slow decoding: correcting a single block usually requires reading
+254 extra blocks spread evenly across the device(s).  However, that is
+acceptable because dm-verity uses FEC only when there is actually an error.
+
+The list below contains additional details about the RS codes used by
+dm-verity's FEC.  Userspace programs that generate the parity data need to use
+these parameters for the parity data to match exactly:
+
+- Field used is GF(256)
+- Bytes are mapped to/from GF(256) elements in the natural way, where bits 0
+  through 7 (low-order to high-order) map to the coefficients of x^0 through x^7
+- Field generator polynomial is x^8 + x^4 + x^3 + x^2 + 1
+- The codes used are systematic, BCH-view codes
+- Primitive element alpha is 'x'
+- First consecutive root of code generator polynomial is 'x^0'
+
+On-disk format
+==============
+
+The verity kernel code does not read the verity metadata on-disk header.
+It only reads the hash blocks which directly follow the header.
+It is expected that a user-space tool will verify the integrity of the
+verity header.
+
+Alternatively, the header can be omitted and the dmsetup parameters can
+be passed via the kernel command-line in a rooted chain of trust where
+the command-line is verified.
+
+Directly following the header (and with sector number padded to the next hash
+block boundary) are the hash blocks which are stored a depth at a time
+(starting from the root), sorted in order of increasing index.
+
+The full specification of kernel parameters and on-disk metadata format
+is available at the cryptsetup project's wiki page
+
+  https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
+
+Status
+======
+1. V (for Valid) is returned if every check performed so far was valid.
+   If any check failed, C (for Corruption) is returned.
+2. Number of corrected blocks by Forward Error Correction.
+   '-' if Forward Error Correction is not enabled.
+
+Example
+=======
+Set up a device::
+
+  # dmsetup create vroot --readonly --table \
+    "0 2097152 verity 1 /dev/sda1 /dev/sda2 4096 4096 262144 1 sha256 "\
+    "4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\
+    "1234000000000000000000000000000000000000000000000000000000000000"
+
+A command line tool veritysetup is available to compute or verify
+the hash tree or activate the kernel device. This is available from
+the cryptsetup upstream repository https://gitlab.com/cryptsetup/cryptsetup/
+(as a libcryptsetup extension).
+
+Create hash on the device::
+
+  # veritysetup format /dev/sda1 /dev/sda2
+  ...
+  Root hash: 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
+
+Activate the device::
+
+  # veritysetup create vroot /dev/sda1 /dev/sda2 \
+    4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
diff --git a/Documentation/admin-guide/device-mapper/writecache.rst b/Documentation/admin-guide/device-mapper/writecache.rst
new file mode 100644
index 000000000..60c16b7fd
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/writecache.rst
@@ -0,0 +1,114 @@
+=================
+Writecache target
+=================
+
+The writecache target caches writes on persistent memory or on SSD. It
+doesn't cache reads because reads are supposed to be cached in page cache
+in normal RAM.
+
+When the device is constructed, the first sector should be zeroed or the
+first sector should contain valid superblock from previous invocation.
+
+Constructor parameters:
+
+1. type of the cache device - "p" or "s"
+	- p - persistent memory
+	- s - SSD
+2. the underlying device that will be cached
+3. the cache device
+4. block size (4096 is recommended; the maximum block size is the page
+   size)
+5. the number of optional parameters (the parameters with an argument
+   count as two)
+
+	start_sector n		(default: 0)
+		offset from the start of cache device in 512-byte sectors
+	high_watermark n	(default: 50)
+		start writeback when the number of used blocks reach this
+		watermark
+	low_watermark x		(default: 45)
+		stop writeback when the number of used blocks drops below
+		this watermark
+	writeback_jobs n	(default: unlimited)
+		limit the number of blocks that are in flight during
+		writeback. Setting this value reduces writeback
+		throughput, but it may improve latency of read requests
+	autocommit_blocks n	(default: 64 for pmem, 65536 for ssd)
+		when the application writes this amount of blocks without
+		issuing the FLUSH request, the blocks are automatically
+		committed
+	autocommit_time ms	(default: 1000)
+		autocommit time in milliseconds. The data is automatically
+		committed if this time passes and no FLUSH request is
+		received
+	fua			(by default on)
+		applicable only to persistent memory - use the FUA flag
+		when writing data from persistent memory back to the
+		underlying device
+	nofua
+		applicable only to persistent memory - don't use the FUA
+		flag when writing back data and send the FLUSH request
+		afterwards
+
+		- some underlying devices perform better with fua, some
+		  with nofua. The user should test it
+	cleaner
+		when this option is activated (either in the constructor
+		arguments or by a message), the cache will not promote
+		new writes (however, writes to already cached blocks are
+		promoted, to avoid data corruption due to misordered
+		writes) and it will gradually writeback any cached
+		data. The userspace can then monitor the cleaning
+		process with "dmsetup status". When the number of cached
+		blocks drops to zero, userspace can unload the
+		dm-writecache target and replace it with dm-linear or
+		other targets.
+	max_age n
+		specifies the maximum age of a block in milliseconds. If
+		a block is stored in the cache for too long, it will be
+		written to the underlying device and cleaned up.
+	metadata_only
+		only metadata is promoted to the cache. This option
+		improves performance for heavier REQ_META workloads.
+	pause_writeback n	(default: 3000)
+		pause writeback if there was some write I/O redirected to
+		the origin volume in the last n milliseconds
+
+Status:
+
+1. error indicator - 0 if there was no error, otherwise error number
+2. the number of blocks
+3. the number of free blocks
+4. the number of blocks under writeback
+5. the number of read blocks
+6. the number of read blocks that hit the cache
+7. the number of write blocks
+8. the number of write blocks that hit uncommitted block
+9. the number of write blocks that hit committed block
+10. the number of write blocks that bypass the cache
+11. the number of write blocks that are allocated in the cache
+12. the number of write requests that are blocked on the freelist
+13. the number of flush requests
+14. the number of discarded blocks
+
+Messages:
+	flush
+		Flush the cache device. The message returns successfully
+		if the cache device was flushed without an error
+	flush_on_suspend
+		Flush the cache device on next suspend. Use this message
+		when you are going to remove the cache device. The proper
+		sequence for removing the cache device is:
+
+		1. send the "flush_on_suspend" message
+		2. load an inactive table with a linear target that maps
+		   to the underlying device
+		3. suspend the device
+		4. ask for status and verify that there are no errors
+		5. resume the device, so that it will use the linear
+		   target
+		6. the cache device is now inactive and it can be deleted
+	cleaner
+		See above "cleaner" constructor documentation.
+	clear_stats
+		Clear the statistics that are reported on the status line
diff --git a/Documentation/admin-guide/device-mapper/zero.rst b/Documentation/admin-guide/device-mapper/zero.rst
new file mode 100644
index 000000000..11fb5cf45
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/zero.rst
@@ -0,0 +1,37 @@
+=======
+dm-zero
+=======
+
+Device-Mapper's "zero" target provides a block-device that always returns
+zero'd data on reads and silently drops writes. This is similar behavior to
+/dev/zero, but as a block-device instead of a character-device.
+
+Dm-zero has no target-specific parameters.
+
+One very interesting use of dm-zero is for creating "sparse" devices in
+conjunction with dm-snapshot. A sparse device reports a device-size larger
+than the amount of actual storage space available for that device. A user can
+write data anywhere within the sparse device and read it back like a normal
+device. Reads to previously unwritten areas will return a zero'd buffer. When
+enough data has been written to fill up the actual storage space, the sparse
+device is deactivated. This can be very useful for testing device and
+filesystem limitations.
+
+To create a sparse device, start by creating a dm-zero device that's the
+desired size of the sparse device. For this example, we'll assume a 10TB
+sparse device::
+
+  TEN_TERABYTES=`expr 10 \* 1024 \* 1024 \* 1024 \* 2`   # 10 TB in sectors
+  echo "0 $TEN_TERABYTES zero" | dmsetup create zero1
+
+Then create a snapshot of the zero device, using any available block-device as
+the COW device. The size of the COW device will determine the amount of real
+space available to the sparse device. For this example, we'll assume /dev/sdb1
+is an available 10GB partition::
+
+  echo "0 $TEN_TERABYTES snapshot /dev/mapper/zero1 /dev/sdb1 p 128" | \
+     dmsetup create sparse1
+
+This will create a 10TB sparse device called /dev/mapper/sparse1 that has
+10GB of actual storage space available. If more than 10GB of data is written
+to this device, it will start returning I/O errors.