Remove blkdev warning triggered by using md

As setting and clearing queue flags now requires that we hold a spinlock
on the queue, and as blk_queue_stack_limits is called without that lock,
get the lock inside blk_queue_stack_limits.

For blk_queue_stack_limits to be able to find the right lock, each md
personality needs to set q->queue_lock to point to the appropriate lock.
Those personalities which didn't previously use a spin_lock, us
q->__queue_lock.  So always initialise that lock when allocated.

With this in place, setting/clearing of the QUEUE_FLAG_PLUGGED bit will no
longer cause warnings as it will be clear that the proper lock is held.

Thanks to Dan Williams for review and fixing the silly bugs.

Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Alistair John Strachan <alistair@devzero.co.uk>
Cc: Nick Piggin <npiggin@suse.de>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Jacek Luczak <difrost.kernel@gmail.com>
Cc: Prakash Punnoor <prakash@punnoor.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 42ee1a2dc144..4f4d1f383842 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -417,6 +417,7 @@ static int multipath_run (mddev_t *mddev)
          * bookkeeping area. [whatever we allocate in multipath_run(),
          * should be freed in multipath_stop()]
          */
+        mddev->queue->queue_lock = &mddev->queue->__queue_lock;
 
         conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
         mddev->private = conf;