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[PATCH] device-mapper multipath: Avoid possible suspension deadlock

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To avoid deadlock when suspending a multipath device after all its paths have
failed, stop queueing any I/O that is about to fail *before* calling
freeze_bdev instead of after.

Instead of setting a multipath 'suspended' flag which would have to be reset
if an error occurs during the process, save the previous queueing state and
leave userspace to restore if it wishes.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Alasdair G Kergon
2005-07-12 15:53:03 -07:00
committed by Linus Torvalds
parent a044d01689
commit 436d41087d
2 changed files with 20 additions and 17 deletions
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12
drivers/md/dm.c
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@@ -1055,14 +1055,17 @@ int dm_suspend(struct mapped_device *md)
if (test_bit(DMF_BLOCK_IO, &md->flags))
goto out_read_unlock;
error = __lock_fs(md);
if (error)
goto out_read_unlock;
map = dm_get_table(md);
if (map)
/* This does not get reverted if there's an error later. */
dm_table_presuspend_targets(map);
error = __lock_fs(md);
if (error) {
dm_table_put(map);
goto out_read_unlock;
}
up_read(&md->lock);
/*
@@ -1121,7 +1124,6 @@ int dm_suspend(struct mapped_device *md)
return 0;
out_unfreeze:
/* FIXME Undo dm_table_presuspend_targets */
__unlock_fs(md);
clear_bit(DMF_BLOCK_IO, &md->flags);
out_write_unlock: