From: Hannes Reinecke <hare@suse.de>
Date: Wed, 10 Jul 2013 22:41:15 +0000 (+0100)
Subject: dm mpath: fix ioctl deadlock when no paths
X-Git-Tag: v3.11-rc1~20^2~12
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6c182cd88d179cbbd06f4f8a8a19b6977940753f;p=pandora-kernel.git

dm mpath: fix ioctl deadlock when no paths

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>
---

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