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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 | |
parent | e540eb45a5254873245fd377f2fe3afc47bd33c1 (diff) | |
download | op-kernel-dev-bfa152fa5e4d328fe3ebf15908ee8ec20a0ce6dc.zip op-kernel-dev-bfa152fa5e4d328fe3ebf15908ee8ec20a0ce6dc.tar.gz |
[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>
-rw-r--r-- | drivers/md/dm.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index fe7c56e..3668b17 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1116,7 +1116,8 @@ static int __bind(struct mapped_device *md, struct dm_table *t) if (size != get_capacity(md->disk)) memset(&md->geometry, 0, sizeof(md->geometry)); - __set_size(md, size); + if (md->suspended_bdev) + __set_size(md, size); if (size == 0) return 0; @@ -1264,6 +1265,11 @@ int dm_swap_table(struct mapped_device *md, struct dm_table *table) if (!dm_suspended(md)) goto out; + /* without bdev, the device size cannot be changed */ + if (!md->suspended_bdev) + if (get_capacity(md->disk) != dm_table_get_size(table)) + goto out; + __unbind(md); r = __bind(md, table); @@ -1341,11 +1347,14 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags) /* This does not get reverted if there's an error later. */ dm_table_presuspend_targets(map); - md->suspended_bdev = bdget_disk(md->disk, 0); - if (!md->suspended_bdev) { - DMWARN("bdget failed in dm_suspend"); - r = -ENOMEM; - goto flush_and_out; + /* bdget() can stall if the pending I/Os are not flushed */ + if (!noflush) { + md->suspended_bdev = bdget_disk(md->disk, 0); + if (!md->suspended_bdev) { + DMWARN("bdget failed in dm_suspend"); + r = -ENOMEM; + goto flush_and_out; + } } /* @@ -1473,8 +1482,10 @@ int dm_resume(struct mapped_device *md) unlock_fs(md); - bdput(md->suspended_bdev); - md->suspended_bdev = NULL; + if (md->suspended_bdev) { + bdput(md->suspended_bdev); + md->suspended_bdev = NULL; + } clear_bit(DMF_SUSPENDED, &md->flags); |