diff options
author | Jun'ichi Nomura <j-nomura@ce.jp.nec.com> | 2007-01-26 00:57:07 -0800 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-01-26 13:51:00 -0800 |
commit | bfa152fa5e4d328fe3ebf15908ee8ec20a0ce6dc (patch) | |
tree | 1695481328f884639d6237eebfa48f4c29f9ce7c /drivers/md/dm.h | |
parent | e540eb45a5254873245fd377f2fe3afc47bd33c1 (diff) |
[PATCH] dm-multipath: fix stall on noflush suspend/resume
Allow noflush suspend/resume of device-mapper device only for the case
where the device size is unchanged.
Otherwise, dm-multipath devices can stall when resumed if noflush was used
when suspending them, all paths have failed and queue_if_no_path is set.
Explanation:
1. Something is doing fsync() on the block dev,
holding inode->i_sem
2. The fsync write is blocked by all-paths-down and queue_if_no_path
3. Someone requests to suspend the dm device with noflush.
Pending writes are left in queue.
4. In the middle of dm_resume(), __bind() tries to get
inode->i_sem to do __set_size() and waits forever.
'noflush suspend' is a new device-mapper feature introduced in
early 2.6.20. So I hope the fix being included before 2.6.20 is
released.
Example of reproducer:
1. Create a multipath device by dmsetup
2. Fail all paths during mkfs
3. Do dmsetup suspend --noflush and load new map with healthy paths
4. Do dmsetup resume
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/md/dm.h')
0 files changed, 0 insertions, 0 deletions