dm mpath: fix ioctl deadlock when no paths

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When multipath needs to retry an ioctl the reference to the
current live table needs to be dropped. Otherwise a deadlock
occurs when all paths are down:
- dm_blk_ioctl takes a reference to the current table
  and spins in multipath_ioctl().
- A new table is being loaded, but upon resume the process
  hangs in dm_table_destroy() waiting for references to
  drop to zero.

With this patch the reference to the old table is dropped
prior to retry, thereby avoiding the deadlock.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

...

This commit is contained in:

Hannes Reinecke 2013-07-10 23:41:15 +01:00 • committed by Alasdair G Kergon

parent 8bb495e3f0

commit 6c182cd88d

2 changed files with 10 additions and 7 deletions

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8

drivers/md/dm-mpath.c

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9

drivers/md/dm.c

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