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md raid: fix hang when stopping arrays with metadata through dm-raid

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When using device-mapper's dm-raid target, stopping a RAID array can cause
the system to hang under specific conditions.

This occurs when:

- A dm-raid managed device tree is suspended from top to bottom
   (the top-level RAID device is suspended first, followed by its
    underlying metadata and data devices)

- The top-level RAID device is then removed

Removing the top-level device triggers a hang in the following sequence:
the dm-raid destructor calls md_stop(), which tries to flush the
write-intent bitmap by writing to the metadata sub-devices. However, these
devices are already suspended, making them unable to complete the write-intent
operations and causing an indefinite block.

Fix:

- Prevent bitmap flushing when md_stop() is called from dm-raid
destructor context
  and avoid a quiescing/unquescing cycle which could also cause I/O

- Still allow write-intent bitmap flushing when called from dm-raid
suspend context

This ensures that RAID array teardown can complete successfully even when the
underlying devices are in a suspended state.

This second patch uses md_is_rdwr() to distinguish between suspend and
destructor paths as elaborated on above.

Link: https://lore.kernel.org/linux-raid/CAM23VxqYrwkhKEBeQrZeZwQudbiNey2_8B_SEOLqug=pXxaFrA@mail.gmail.com
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Yu Kuai <yukuai@fnnas.com>
This commit is contained in:
Heinz Mauelshagen
2026-01-14 18:52:21 +01:00
committed by Yu Kuai
parent f150e753cb
commit cefcb9297f
1 changed files with 8 additions and 6 deletions
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14
drivers/md/md.c
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@@ -6851,13 +6851,15 @@ static void __md_stop_writes(struct mddev *mddev)
{
timer_delete_sync(&mddev->safemode_timer);
if (mddev->pers && mddev->pers->quiesce) {
mddev->pers->quiesce(mddev, 1);
mddev->pers->quiesce(mddev, 0);
}
if (md_is_rdwr(mddev) || !mddev_is_dm(mddev)) {
if (mddev->pers && mddev->pers->quiesce) {
mddev->pers->quiesce(mddev, 1);
mddev->pers->quiesce(mddev, 0);
}
if (md_bitmap_enabled(mddev, true))
mddev->bitmap_ops->flush(mddev);
if (md_bitmap_enabled(mddev, true))
mddev->bitmap_ops->flush(mddev);
}
if (md_is_rdwr(mddev) &&
((!mddev->in_sync && !mddev_is_clustered(mddev)) ||