linux-kernel - [PATCH 4.7 051/186] dm: set DMF_SUSPENDED* _before_ clearing DMF_NOFLUSH

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Date:	Thu, 18 Aug 2016 15:57:48 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Bart Van Assche <bart.vanassche@...disk.com>,
	Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 4.7 051/186] dm: set DMF_SUSPENDED* _before_ clearing DMF_NOFLUSH_SUSPENDING

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <snitzer@...hat.com>

commit eaf9a7361f47727b166688a9f2096854eef60fbe upstream.

Otherwise, there is potential for both DMF_SUSPENDED* and
DMF_NOFLUSH_SUSPENDING to not be set during dm_suspend() -- which is
definitely _not_ a valid state.

This fix, in conjuction with "dm rq: fix the starting and stopping of
blk-mq queues", addresses the potential for request-based DM multipath's
__multipath_map() to see !dm_noflush_suspending() during suspend.

Reported-by: Bart Van Assche <bart.vanassche@...disk.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/dm.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -3128,7 +3128,8 @@ static void unlock_fs(struct mapped_devi
  * Caller must hold md->suspend_lock
  */
 static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
-			unsigned suspend_flags, int interruptible)
+			unsigned suspend_flags, int interruptible,
+			int dmf_suspended_flag)
 {
 	bool do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG;
 	bool noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG;
@@ -3195,6 +3196,8 @@ static int __dm_suspend(struct mapped_de
 	 * to finish.
 	 */
 	r = dm_wait_for_completion(md, interruptible);
+	if (!r)
+		set_bit(dmf_suspended_flag, &md->flags);
 
 	if (noflush)
 		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
@@ -3256,12 +3259,10 @@ retry:
 
 	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
 
-	r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE);
+	r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE, DMF_SUSPENDED);
 	if (r)
 		goto out_unlock;
 
-	set_bit(DMF_SUSPENDED, &md->flags);
-
 	dm_table_postsuspend_targets(map);
 
 out_unlock:
@@ -3355,9 +3356,8 @@ static void __dm_internal_suspend(struct
 	 * would require changing .presuspend to return an error -- avoid this
 	 * until there is a need for more elaborate variants of internal suspend.
 	 */
-	(void) __dm_suspend(md, map, suspend_flags, TASK_UNINTERRUPTIBLE);
-
-	set_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
+	(void) __dm_suspend(md, map, suspend_flags, TASK_UNINTERRUPTIBLE,
+			    DMF_SUSPENDED_INTERNALLY);
 
 	dm_table_postsuspend_targets(map);
 }