linux.git/drivers/md/md-bitmap.c, branch v7.3-rc2

md/md-llbitmap: add reshape range mapping helpers

2026-08-07T06:43:35+00:00

Teach llbitmap to choose old versus new geometry during reshape and to
encode exact bitmap ranges for the active geometry. This is the mapping
groundwork for checkpoint remapping.

Range preparation now distinguishes writes from discards. Normal writes
must cover every touched bitmap chunk, while discards may only mark fully
covered chunks unwritten. Without this distinction, a discard that starts
or ends inside a chunk can make live data look unwritten after the range
has been mapped and floored.

Reproduce that with a RAID1 llbitmap using 128-sector chunks. A discard
starting halfway into chunk 8 with a 128-sector length changed clean bits
from 16352 to 16350 and unwritten bits from 0 to 2, even though no chunk
was fully discarded. With discard-specific range encoding, both counts
stay unchanged for the same test.

Range preparation also clamps the pre-map range in the same coordinate
space as the incoming IO. RAID5 receives array-sector offsets but tracks
llbitmap sync size in component sectors, so steady-state RAID5 must use
bitmap_array_sectors() before mapping and keep the existing sync-size
clamp after mapping.

Reproduce that with a 4-disk RAID5 llbitmap created --assume-clean. A
write below dev_sectors changed dirty bits from 0 to 512, but a write at
seek=2094080 left the count at 512. With the array-sector pre-map limit,
writing at seek=component_size + 65536 increased dirty bits from 512 to
1024.

Link: https://lore.kernel.org/all/20260726185916.2223460-1-mykola@meshstor.io/
Tested-by: Mykola Marzhan 
Link: https://patch.msgid.link/20260802195038.164272-20-yukuai@kernel.org
Signed-off-by: Yu Kuai

md: add exact bitmap mapping and reshape hooks

2026-08-07T06:43:34+00:00

Add bitmap mapping and reshape hooks needed by llbitmap reshape
support without teaching md core to account a single bio against
multiple bitmap ranges.

This also adds the old/new bitmap geometry helpers used by
personalities to describe reshape mapping to llbitmap.

Tested-by: Mykola Marzhan 
Link: https://patch.msgid.link/20260802195038.164272-13-yukuai@kernel.org
Signed-off-by: Yu Kuai

md: scope memalloc_noio to allocation critical sections

2026-07-31T05:22:37+00:00

Storing a memalloc_noio_save() token in mddev->noio_flags lets one task
save the token and another task restore it. With concurrent suspend sysfs
writes, task A can enter PF_MEMALLOC_NOIO, return to userspace still in
that scope, and later task B can restore A's saved token.

Avoid tying the token lifetime to mddev. Keep mddev_suspend() and
mddev_resume() only responsible for array suspension, and enter
PF_MEMALLOC_NOIO only in the MD paths that allocate memory after the array
has been suspended. Restore the token before resuming the array.

A reproducer repeatedly writes suspend_lo and suspend_hi from concurrent
workers and checks each worker's /proc/self/stat flags before and after the
sysfs write.

Link: https://github.com/chencheng-fnnas/reproducer/blob/main/repro-md-noio-token-leak.sh
Fixes: 78f57ef9d50a ("md: use memalloc scope APIs in mddev_suspend()/mddev_resume()")
Signed-off-by: Chen Cheng 
Reviewed-by: Yu Kuai 
Link: https://patch.msgid.link/20260718084218.417895-1-chencheng@fnnas.com
Signed-off-by: Yu Kuai

md/bitmap: resume array on backlog_store() error path

2026-07-31T05:04:41+00:00

backlog_store() suspends the array before checking whether a write-mostly
device exists. If no such device exists, the error path only unlocks
reconfig_mutex and leaves the array suspended, blocking subsequent I/O.

Use mddev_unlock_and_resume() to release both states.

Fixes: 58226942ad3d ("md: use new apis to suspend array before mddev_create/destroy_serial_pool")

Signed-off-by: Chen Cheng 
Reviewed-by: Yu Kuai 
Link: https://patch.msgid.link/20260718034236.4119093-1-chencheng@fnnas.com
Signed-off-by: Yu Kuai

md: remove REQ_NOWAIT support from raid1/10/456

2026-07-30T10:46:32+00:00

REQ_NOWAIT support in md personalities that can block internally is
fundamentally incomplete. While reads can avoid some blocking paths,
write requests can still encounter cases where one mirror succeeds while
another returns -EAGAIN. At that point md cannot distinguish queue
pressure from a real device failure, so it can neither record a bad
block nor safely retry the write without REQ_NOWAIT, leaving mirrors
with divergent data.

Rather than continue advertising REQ_NOWAIT support for personalities
that cannot implement it correctly, remove it from raid1, raid10 and
raid456. Keep REQ_NOWAIT for linear and raid0, which only remap bios to
their underlying devices; stacked limits will still clear the feature if
any component device lacks REQ_NOWAIT support.

Fixes: bf2c411bb1cf ("md: raid456 add nowait support")
Fixes: c9aa889b035f ("md: raid10 add nowait support")
Fixes: 5aa705039c4f ("md: raid1 add nowait support")
Fixes: f51d46d0e7cb ("md: add support for REQ_NOWAIT")
Suggested-by: Yu Kuai 
Signed-off-by: Abd-Alrhman Masalkhi 
Reviewed-by: Yu Kuai 
Link: https://patch.msgid.link/20260628142737.1051059-1-abd.masalkhi@gmail.com
Signed-off-by: Yu Kuai

md/raid1: honor REQ_NOWAIT when waiting for behind writes

2026-06-20T20:19:27+00:00

raid1 supports REQ_NOWAIT reads by avoiding waits in the barrier path
through wait_read_barrier(). However, a read can still block on a
WriteMostly device when the array uses a bitmap and there are
outstanding behind writes.

In that case raid1 unconditionally calls wait_behind_writes(), which
may sleep until all behind writes complete. As a result, a REQ_NOWAIT
read can block despite the caller explicitly requesting non-blocking
behavior.

This ensures that raid1 consistently honors REQ_NOWAIT reads across all
paths that may otherwise wait for behind writes.

Fixes: 5aa705039c4f ("md: raid1 add nowait support")
Signed-off-by: Abd-Alrhman Masalkhi 
Link: https://patch.msgid.link/20260611083514.754922-1-abd.masalkhi@gmail.com
Signed-off-by: Yu Kuai

Merge tag 'vfs-7.2-rc1.bh' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-06-14T22:06:08+00:00

Pull buffer_head updates from Christian Brauner:
 "This removes b_end_io from struct buffer_head.

  Instead of setting bio->bi_end_io to end_bio_bh_io_sync() which then
  calls bh->b_end_io(), the new bh_submit() and __bh_submit() interfaces
  set bio->bi_end_io to the appropriate completion handler directly,
  replacing two indirect function calls in the completion path with one.
  It is also one fewer function pointer in the middle of a writable data
  structure that can be corrupted, it shrinks struct buffer_head from
  104 to 96 bytes allowing roughly 7% more buffer_heads to be cached in
  the same amount of memory, and it removes some atomic operations as
  the buffer refcount is no longer incremented before calling the end_io
  handler.

  All in-tree users (fs/buffer.c itself, ext4, jbd2, ocfs2, gfs2,
  nilfs2, and md-bitmap) are converted, and submit_bh(),
  mark_buffer_async_write(), and end_buffer_write_sync() are removed"

* tag 'vfs-7.2-rc1.bh' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (34 commits)
  buffer: Remove end_buffer_write_sync()
  buffer: Change calling convention for end_buffer_read_sync()
  buffer: Remove b_end_io
  buffer: Remove submit_bh()
  md-bitmap: Convert read_file_page and write_file_page to bh_submit()
  nilfs2: Convert nilfs_mdt_submit_block to bh_submit()
  nilfs2: Convert nilfs_gccache_submit_read_data to bh_submit()
  nilfs2: Convert nilfs_btnode_submit_block to bh_submit()
  buffer: Remove mark_buffer_async_write()
  gfs2: Convert gfs2_aspace_write_folio to bh_submit()
  gfs2: Remove use of b_end_io in gfs2_meta_read_endio()
  gfs2: Convert gfs2_dir_readahead to bh_submit()
  gfs2: Convert gfs2_metapath_ra to bh_submit()
  ocfs2: Convert ocfs2_write_super_or_backup to bh_submit()
  ocfs2: Convert ocfs2_read_blocks to bh_submit()
  ocfs2: Convert ocfs2_read_block to bh_submit()
  ocfs2: Convert ocfs2_write_block to bh_submit()
  jbd2: Convert jbd2_write_superblock() to bh_submit()
  jbd2: Convert journal commit to bh_submit()
  ext4: Convert ext4_commit_super() to bh_submit()
  ...

md-bitmap: Convert read_file_page and write_file_page to bh_submit()

2026-06-04T08:28:10+00:00

Avoid an extra indirect function call by using bh_submit() instead of
submit_bh().

Signed-off-by: Matthew Wilcox (Oracle) 
Link: https://patch.msgid.link/20260528173150.1093780-31-willy@infradead.org
Reviewed-by: Jan Kara 
Cc: linux-raid@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

md/md-bitmap: add a none backend for bitmap grow

2026-04-28T12:44:38+00:00

Add a real none bitmap backend that exposes the common bitmap sysfs
group and use it to keep bitmap/location available when an array has no
bitmap.

Then switch the bitmap location sysfs path to move only between none
and the classic bitmap backend, using the no-sysfs bitmap helpers while
merging or unmerging the internal bitmap sysfs group.

This restores mdadm --grow bitmap addition through bitmap/location.

Fixes: fb8cc3b0d9db ("md/md-bitmap: delay registration of bitmap_ops until creating bitmap")
Reviewed-by: Su Yue 
Link: https://lore.kernel.org/r/20260425024615.1696892-4-yukuai@fnnas.com
Signed-off-by: Yu Kuai

md/md-bitmap: split bitmap sysfs groups

2026-04-28T12:44:37+00:00

Split the classic bitmap sysfs files into a common bitmap group with
the location attribute and a separate internal bitmap group for the
remaining files.

At the same time, convert bitmap operations from a single sysfs group
to a sysfs group array so backends can share part of their sysfs
layout while adding backend-specific attributes separately.

Switch the bitmap sysfs helpers to use sysfs_update_groups() for the
add and update path, and remove groups in reverse order so shared named
groups are unmerged before the last group removes the directory.

Also make bitmap operation lookup depend only on the currently selected
bitmap id matching the installed backend. This prepares the lookup path
for a later registered none backend.

Reviewed-by: Su Yue 
Link: https://lore.kernel.org/r/20260425024615.1696892-3-yukuai@fnnas.com
Signed-off-by: Yu Kuai