netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 115 insertions, 0 deletions

diff --git a/drivers/md/Makefile b/drivers/md/Makefile
new file mode 100644
index 000000000..517d1f7d8
--- /dev/null
+++ b/drivers/md/Makefile
@@ -0,0 +1,115 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the kernel software RAID and LVM drivers.
+#
+
+dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
+		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
+		   dm-rq.o dm-io-rewind.o
+dm-multipath-y	+= dm-path-selector.o dm-mpath.o
+dm-historical-service-time-y += dm-ps-historical-service-time.o
+dm-io-affinity-y += dm-ps-io-affinity.o
+dm-queue-length-y += dm-ps-queue-length.o
+dm-round-robin-y += dm-ps-round-robin.o
+dm-service-time-y += dm-ps-service-time.o
+dm-snapshot-y	+= dm-snap.o dm-exception-store.o dm-snap-transient.o \
+		    dm-snap-persistent.o
+dm-mirror-y	+= dm-raid1.o
+dm-log-userspace-y += dm-log-userspace-base.o dm-log-userspace-transfer.o
+dm-bio-prison-y += dm-bio-prison-v1.o dm-bio-prison-v2.o
+dm-thin-pool-y	+= dm-thin.o dm-thin-metadata.o
+dm-cache-y	+= dm-cache-target.o dm-cache-metadata.o dm-cache-policy.o \
+		    dm-cache-background-tracker.o
+dm-cache-smq-y	+= dm-cache-policy-smq.o
+dm-ebs-y	+= dm-ebs-target.o
+dm-era-y	+= dm-era-target.o
+dm-clone-y	+= dm-clone-target.o dm-clone-metadata.o
+dm-verity-y	+= dm-verity-target.o
+dm-zoned-y	+= dm-zoned-target.o dm-zoned-metadata.o dm-zoned-reclaim.o
+
+md-mod-y	+= md.o
+md-mod-$(CONFIG_MD_BITMAP)	+= md-bitmap.o
+md-mod-$(CONFIG_MD_LLBITMAP)	+= md-llbitmap.o
+raid456-y	+= raid5.o raid5-cache.o raid5-ppl.o
+linear-y       += md-linear.o
+
+# Note: link order is important.  All raid personalities
+# and must come before md.o, as they each initialise
+# themselves, and md.o may use the personalities when it
+# auto-initialised.
+
+obj-$(CONFIG_MD_LINEAR)		+= linear.o
+obj-$(CONFIG_MD_RAID0)		+= raid0.o
+obj-$(CONFIG_MD_RAID1)		+= raid1.o
+obj-$(CONFIG_MD_RAID10)		+= raid10.o
+obj-$(CONFIG_MD_RAID456)	+= raid456.o
+obj-$(CONFIG_MD_CLUSTER)	+= md-cluster.o
+obj-$(CONFIG_BCACHE)		+= bcache/
+obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
+ifeq ($(CONFIG_BLK_DEV_MD),y)
+obj-y				+= md-autodetect.o
+endif
+obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
+obj-$(CONFIG_BLK_DEV_DM_BUILTIN) += dm-builtin.o
+obj-$(CONFIG_DM_UNSTRIPED)	+= dm-unstripe.o
+obj-$(CONFIG_DM_BUFIO)		+= dm-bufio.o
+obj-$(CONFIG_DM_BIO_PRISON)	+= dm-bio-prison.o
+obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o
+obj-$(CONFIG_DM_INLINECRYPT)	+= dm-inlinecrypt.o
+obj-$(CONFIG_DM_DELAY)		+= dm-delay.o
+obj-$(CONFIG_DM_DUST)		+= dm-dust.o
+obj-$(CONFIG_DM_FLAKEY)		+= dm-flakey.o
+obj-$(CONFIG_DM_MULTIPATH)	+= dm-multipath.o dm-round-robin.o
+obj-$(CONFIG_DM_MULTIPATH_QL)	+= dm-queue-length.o
+obj-$(CONFIG_DM_MULTIPATH_ST)	+= dm-service-time.o
+obj-$(CONFIG_DM_MULTIPATH_HST)	+= dm-historical-service-time.o
+obj-$(CONFIG_DM_MULTIPATH_IOA)	+= dm-io-affinity.o
+obj-$(CONFIG_DM_SWITCH)		+= dm-switch.o
+obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
+obj-$(CONFIG_DM_PERSISTENT_DATA) += persistent-data/
+obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o dm-log.o dm-region-hash.o
+obj-$(CONFIG_DM_LOG_USERSPACE)	+= dm-log-userspace.o
+obj-$(CONFIG_DM_ZERO)		+= dm-zero.o
+obj-$(CONFIG_DM_RAID)		+= dm-raid.o
+obj-$(CONFIG_DM_THIN_PROVISIONING) += dm-thin-pool.o
+obj-$(CONFIG_DM_VERITY)		+= dm-verity.o
+obj-$(CONFIG_DM_VDO)            += dm-vdo/
+obj-$(CONFIG_DM_PCACHE)		+= dm-pcache/
+obj-$(CONFIG_DM_CACHE)		+= dm-cache.o
+obj-$(CONFIG_DM_CACHE_SMQ)	+= dm-cache-smq.o
+obj-$(CONFIG_DM_EBS)		+= dm-ebs.o
+obj-$(CONFIG_DM_ERA)		+= dm-era.o
+obj-$(CONFIG_DM_CLONE)		+= dm-clone.o
+obj-$(CONFIG_DM_LOG_WRITES)	+= dm-log-writes.o
+obj-$(CONFIG_DM_INTEGRITY)	+= dm-integrity.o
+obj-$(CONFIG_DM_ZONED)		+= dm-zoned.o
+obj-$(CONFIG_DM_WRITECACHE)	+= dm-writecache.o
+obj-$(CONFIG_SECURITY_LOADPIN_VERITY)	+= dm-verity-loadpin.o
+
+ifeq ($(CONFIG_DM_INIT),y)
+dm-mod-objs			+= dm-init.o
+endif
+
+ifeq ($(CONFIG_DM_UEVENT),y)
+dm-mod-objs			+= dm-uevent.o
+endif
+
+ifeq ($(CONFIG_BLK_DEV_ZONED),y)
+dm-mod-objs			+= dm-zone.o
+endif
+
+ifeq ($(CONFIG_IMA),y)
+dm-mod-objs			+= dm-ima.o
+endif
+
+ifeq ($(CONFIG_DM_VERITY_FEC),y)
+dm-verity-objs			+= dm-verity-fec.o
+endif
+
+ifeq ($(CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG),y)
+dm-verity-objs			+= dm-verity-verify-sig.o
+endif
+
+ifeq ($(CONFIG_DM_AUDIT),y)
+dm-mod-objs			+= dm-audit.o
+endif