dm mpath: fix lock order inconsistency in multipath_ioctl

Commit 3e9f1be1b40 ("dm mpath: remove process_queued_ios()") did not
consistently take the multipath device's spinlock (m->lock) before
calling dm_table_run_md_queue_async() -- which takes the q->queue_lock.

Found with code inspection using hint from reported lockdep warning.

Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index aa009e8..fa0f6cb 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1566,8 +1566,8 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
                }
                if (m->pg_init_required)
                        __pg_init_all_paths(m);
-               spin_unlock_irqrestore(&m->lock, flags);
                dm_table_run_md_queue_async(m->ti->table);
+               spin_unlock_irqrestore(&m->lock, flags);
        }
 
        return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);