From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- .../blockdev/drbd/DRBD-8.3-data-packets.svg | 588 +++++++++++++++++++++ .../blockdev/drbd/DRBD-data-packets.svg | 459 ++++++++++++++++ .../admin-guide/blockdev/drbd/conn-states-8.dot | 18 + .../blockdev/drbd/data-structure-v9.rst | 42 ++ .../admin-guide/blockdev/drbd/disk-states-8.dot | 16 + .../drbd/drbd-connection-state-overview.dot | 85 +++ .../admin-guide/blockdev/drbd/figures.rst | 30 ++ Documentation/admin-guide/blockdev/drbd/index.rst | 19 + .../admin-guide/blockdev/drbd/peer-states-8.dot | 8 + 9 files changed, 1265 insertions(+) create mode 100644 Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg create mode 100644 Documentation/admin-guide/blockdev/drbd/DRBD-data-packets.svg create mode 100644 Documentation/admin-guide/blockdev/drbd/conn-states-8.dot create mode 100644 Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst create mode 100644 Documentation/admin-guide/blockdev/drbd/disk-states-8.dot create mode 100644 Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot create mode 100644 Documentation/admin-guide/blockdev/drbd/figures.rst create mode 100644 Documentation/admin-guide/blockdev/drbd/index.rst create mode 100644 Documentation/admin-guide/blockdev/drbd/peer-states-8.dot (limited to 'Documentation/admin-guide/blockdev/drbd') diff --git a/Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg b/Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg new file mode 100644 index 000000000..f87cfa0dc --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg @@ -0,0 +1,588 @@ + + + + + + Master slide + + + + + + + + + + RSDataReply + + + + + + + CsumRSRequest + + + + w_make_resync_request() + + + receive_DataRequest() + + + drbd_endio_read_sec() + + + w_e_end_csum_rs_req() + + + receive_RSDataReply() + + + drbd_endio_write_sec() + + + e_end_resync_block() + + + + + + WriteAck + + + + got_BlockAck() + + + Checksum based Resync, case not in sync + + + DRBD-8.3 data flow + + + w_e_send_csum() + + + + + + + + RSIsInSync + + + + + + + CsumRSRequest + + + + receive_DataRequest() + + + drbd_endio_read_sec() + + + w_e_end_csum_rs_req() + + + got_IsInSync() + + + Checksum based Resync, case in sync + + + + + + + + + + OVReply + + + + + + + OVRequest + + + + receive_OVRequest() + + + drbd_endio_read_sec() + + + w_e_end_ov_req() + + + receive_OVReply() + + + drbd_endio_read_sec() + + + w_e_end_ov_reply() + + + + + + OVResult + + + + got_OVResult() + + + Online verify + + + w_make_ov_request() + + + + + + + + drbd_endio_read_sec() + + + w_make_resync_request() + + + w_e_send_csum() + + + + + drbd_endio_read_sec() + + + + + + rs_begin_io() + + + rs_begin_io() + + + rs_begin_io() + + + rs_complete_io() + + + rs_complete_io() + + + rs_complete_io() + + + rs_begin_io() + + + rs_begin_io() + + + rs_begin_io() + + + rs_complete_io() + + + rs_complete_io() + + + rs_complete_io() + + diff --git a/Documentation/admin-guide/blockdev/drbd/DRBD-data-packets.svg b/Documentation/admin-guide/blockdev/drbd/DRBD-data-packets.svg new file mode 100644 index 000000000..48a1e2165 --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/DRBD-data-packets.svg @@ -0,0 +1,459 @@ + + + + + + Master slide + + + + + + + + + RSDataReply + + + + + RSDataRequest + + + w_make_resync_request() + + + receive_DataRequest() + + + drbd_endio_read_sec() + + + w_e_end_rsdata_req() + + + receive_RSDataReply() + + + drbd_endio_write_sec() + + + e_end_resync_block() + + + + + WriteAck + + + got_BlockAck() + + + Resync blocks, 4-32K + + + + + + + WriteAck + + + + + Data + + + drbd_make_request() + + + receive_Data() + + + drbd_endio_write_sec() + + + e_end_block() + + + got_BlockAck() + + + Regular mirrored write, 512-32K + + + w_send_dblock() + + + + + drbd_endio_write_pri() + + + + + + + DataReply + + + + + DataRequest + + + drbd_make_request() + + + receive_DataRequest() + + + drbd_endio_read_sec() + + + w_e_end_data_req() + + + Drawing + + receive_DataReply() + + + + Diskless read, 512-32K + + + w_send_read_req() + + + DRBD 8 data flow + + + + + + al_begin_io() + + + al_complete_io() + + + rs_begin_io() + + + rs_complete_io() + + + rs_begin_io() + + + rs_complete_io() + + diff --git a/Documentation/admin-guide/blockdev/drbd/conn-states-8.dot b/Documentation/admin-guide/blockdev/drbd/conn-states-8.dot new file mode 100644 index 000000000..025e8cf5e --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/conn-states-8.dot @@ -0,0 +1,18 @@ +digraph conn_states { + StandAllone -> WFConnection [ label = "ioctl_set_net()" ] + WFConnection -> Unconnected [ label = "unable to bind()" ] + WFConnection -> WFReportParams [ label = "in connect() after accept" ] + WFReportParams -> StandAllone [ label = "checks in receive_param()" ] + WFReportParams -> Connected [ label = "in receive_param()" ] + WFReportParams -> WFBitMapS [ label = "sync_handshake()" ] + WFReportParams -> WFBitMapT [ label = "sync_handshake()" ] + WFBitMapS -> SyncSource [ label = "receive_bitmap()" ] + WFBitMapT -> SyncTarget [ label = "receive_bitmap()" ] + SyncSource -> Connected + SyncTarget -> Connected + SyncSource -> PausedSyncS + SyncTarget -> PausedSyncT + PausedSyncS -> SyncSource + PausedSyncT -> SyncTarget + Connected -> WFConnection [ label = "* on network error" ] +} diff --git a/Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst b/Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst new file mode 100644 index 000000000..66036b901 --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst @@ -0,0 +1,42 @@ +================================ +kernel data structure for DRBD-9 +================================ + +This describes the in kernel data structure for DRBD-9. Starting with +Linux v3.14 we are reorganizing DRBD to use this data structure. + +Basic Data Structure +==================== + +A node has a number of DRBD resources. Each such resource has a number of +devices (aka volumes) and connections to other nodes ("peer nodes"). Each DRBD +device is represented by a block device locally. + +The DRBD objects are interconnected to form a matrix as depicted below; a +drbd_peer_device object sits at each intersection between a drbd_device and a +drbd_connection:: + + /--------------+---------------+.....+---------------\ + | resource | device | | device | + +--------------+---------------+.....+---------------+ + | connection | peer_device | | peer_device | + +--------------+---------------+.....+---------------+ + : : : : : + : : : : : + +--------------+---------------+.....+---------------+ + | connection | peer_device | | peer_device | + \--------------+---------------+.....+---------------/ + +In this table, horizontally, devices can be accessed from resources by their +volume number. Likewise, peer_devices can be accessed from connections by +their volume number. Objects in the vertical direction are connected by double +linked lists. There are back pointers from peer_devices to their connections a +devices, and from connections and devices to their resource. + +All resources are in the drbd_resources double-linked list. In addition, all +devices can be accessed by their minor device number via the drbd_devices idr. + +The drbd_resource, drbd_connection, and drbd_device objects are reference +counted. The peer_device objects only serve to establish the links between +devices and connections; their lifetime is determined by the lifetime of the +device and connection which they reference. diff --git a/Documentation/admin-guide/blockdev/drbd/disk-states-8.dot b/Documentation/admin-guide/blockdev/drbd/disk-states-8.dot new file mode 100644 index 000000000..d06cfb46f --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/disk-states-8.dot @@ -0,0 +1,16 @@ +digraph disk_states { + Diskless -> Inconsistent [ label = "ioctl_set_disk()" ] + Diskless -> Consistent [ label = "ioctl_set_disk()" ] + Diskless -> Outdated [ label = "ioctl_set_disk()" ] + Consistent -> Outdated [ label = "receive_param()" ] + Consistent -> UpToDate [ label = "receive_param()" ] + Consistent -> Inconsistent [ label = "start resync" ] + Outdated -> Inconsistent [ label = "start resync" ] + UpToDate -> Inconsistent [ label = "ioctl_replicate" ] + Inconsistent -> UpToDate [ label = "resync completed" ] + Consistent -> Failed [ label = "io completion error" ] + Outdated -> Failed [ label = "io completion error" ] + UpToDate -> Failed [ label = "io completion error" ] + Inconsistent -> Failed [ label = "io completion error" ] + Failed -> Diskless [ label = "sending notify to peer" ] +} diff --git a/Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot b/Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot new file mode 100644 index 000000000..6d9cf0a7b --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot @@ -0,0 +1,85 @@ +// vim: set sw=2 sts=2 : +digraph { + rankdir=BT + bgcolor=white + + node [shape=plaintext] + node [fontcolor=black] + + StandAlone [ style=filled,fillcolor=gray,label=StandAlone ] + + node [fontcolor=lightgray] + + Unconnected [ label=Unconnected ] + + CommTrouble [ shape=record, + label="{communication loss|{Timeout|BrokenPipe|NetworkFailure}}" ] + + node [fontcolor=gray] + + subgraph cluster_try_connect { + label="try to connect, handshake" + rank=max + WFConnection [ label=WFConnection ] + WFReportParams [ label=WFReportParams ] + } + + TearDown [ label=TearDown ] + + Connected [ label=Connected,style=filled,fillcolor=green,fontcolor=black ] + + node [fontcolor=lightblue] + + StartingSyncS [ label=StartingSyncS ] + StartingSyncT [ label=StartingSyncT ] + + subgraph cluster_bitmap_exchange { + node [fontcolor=red] + fontcolor=red + label="new application (WRITE?) requests blocked\lwhile bitmap is exchanged" + + WFBitMapT [ label=WFBitMapT ] + WFSyncUUID [ label=WFSyncUUID ] + WFBitMapS [ label=WFBitMapS ] + } + + node [fontcolor=blue] + + cluster_resync [ shape=record,label="{resynchronisation process running\l'concurrent' application requests allowed|{{PausedSyncT\nSyncTarget}|{PausedSyncS\nSyncSource}}}" ] + + node [shape=box,fontcolor=black] + + // drbdadm [label="drbdadm connect"] + // handshake [label="drbd_connect()\ndrbd_do_handshake\ndrbd_sync_handshake() etc."] + // comm_error [label="communication trouble"] + + // + // edges + // -------------------------------------- + + StandAlone -> Unconnected [ label="drbdadm connect" ] + Unconnected -> StandAlone [ label="drbdadm disconnect\lor serious communication trouble" ] + Unconnected -> WFConnection [ label="receiver thread is started" ] + WFConnection -> WFReportParams [ headlabel="accept()\land/or \lconnect()\l" ] + + WFReportParams -> StandAlone [ label="during handshake\lpeers do not agree\labout something essential" ] + WFReportParams -> Connected [ label="data identical\lno sync needed",color=green,fontcolor=green ] + + WFReportParams -> WFBitMapS + WFReportParams -> WFBitMapT + WFBitMapT -> WFSyncUUID [minlen=0.1,constraint=false] + + WFBitMapS -> cluster_resync:S + WFSyncUUID -> cluster_resync:T + + edge [color=green] + cluster_resync:any -> Connected [ label="resnyc done",fontcolor=green ] + + edge [color=red] + WFReportParams -> CommTrouble + Connected -> CommTrouble + cluster_resync:any -> CommTrouble + edge [color=black] + CommTrouble -> Unconnected [label="receiver thread is stopped" ] + +} diff --git a/Documentation/admin-guide/blockdev/drbd/figures.rst b/Documentation/admin-guide/blockdev/drbd/figures.rst new file mode 100644 index 000000000..9f73253ea --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/figures.rst @@ -0,0 +1,30 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. The here included files are intended to help understand the implementation + +Data flows that Relate some functions, and write packets +======================================================== + +.. kernel-figure:: DRBD-8.3-data-packets.svg + :alt: DRBD-8.3-data-packets.svg + :align: center + +.. kernel-figure:: DRBD-data-packets.svg + :alt: DRBD-data-packets.svg + :align: center + + +Sub graphs of DRBD's state transitions +====================================== + +.. kernel-figure:: conn-states-8.dot + :alt: conn-states-8.dot + :align: center + +.. kernel-figure:: disk-states-8.dot + :alt: disk-states-8.dot + :align: center + +.. kernel-figure:: peer-states-8.dot + :alt: peer-states-8.dot + :align: center diff --git a/Documentation/admin-guide/blockdev/drbd/index.rst b/Documentation/admin-guide/blockdev/drbd/index.rst new file mode 100644 index 000000000..561fd1e35 --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/index.rst @@ -0,0 +1,19 @@ +========================================== +Distributed Replicated Block Device - DRBD +========================================== + +Description +=========== + + DRBD is a shared-nothing, synchronously replicated block device. It + is designed to serve as a building block for high availability + clusters and in this context, is a "drop-in" replacement for shared + storage. Simplistically, you could see it as a network RAID 1. + + Please visit https://www.drbd.org to find out more. + +.. toctree:: + :maxdepth: 1 + + data-structure-v9 + figures diff --git a/Documentation/admin-guide/blockdev/drbd/peer-states-8.dot b/Documentation/admin-guide/blockdev/drbd/peer-states-8.dot new file mode 100644 index 000000000..6dc395495 --- /dev/null +++ b/Documentation/admin-guide/blockdev/drbd/peer-states-8.dot @@ -0,0 +1,8 @@ +digraph peer_states { + Secondary -> Primary [ label = "recv state packet" ] + Primary -> Secondary [ label = "recv state packet" ] + Primary -> Unknown [ label = "connection lost" ] + Secondary -> Unknown [ label = "connection lost" ] + Unknown -> Primary [ label = "connected" ] + Unknown -> Secondary [ label = "connected" ] +} -- cgit v1.3.1