Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7083abbb authored by Bart Van Assche's avatar Bart Van Assche Committed by Mike Snitzer
Browse files

dm mpath: avoid that path removal can trigger an infinite loop 



If blk_get_request() fails, check whether the failure is due to a path
being removed.  If that is the case, fail the path by triggering a call
to fail_path().  This avoids that the following scenario can be
encountered while removing paths:
* CPU usage of a kworker thread jumps to 100%.
* Removing the DM device becomes impossible.

Delay requeueing if blk_get_request() returns -EBUSY or -EWOULDBLOCK,
and the queue is not dying, because in these cases immediate requeuing
is inappropriate.

Signed-off-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 89bfce76

drivers/md/dm-mpath.c

+11 −4
Original line number Diff line number Diff line
@@ -489,6 +489,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, 
	struct pgpath *pgpath;

	struct block_device *bdev;

	struct dm_mpath_io *mpio = get_mpio(map_context);

	struct request_queue *q;

	struct request *clone;



	/* Do we need to select a new pgpath? */
@@ -511,12 +512,18 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, 
	mpio->nr_bytes = nr_bytes;



	bdev = pgpath->path.dev->bdev;



	clone = blk_get_request(bdev_get_queue(bdev),

			rq->cmd_flags | REQ_NOMERGE,

			GFP_ATOMIC);

	q = bdev_get_queue(bdev);

	clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);

	if (IS_ERR(clone)) {

		/* EBUSY, ENODEV or EWOULDBLOCK: requeue */

		bool queue_dying = blk_queue_dying(q);

		DMERR_LIMIT("blk_get_request() returned %ld%s - requeuing",

			    PTR_ERR(clone), queue_dying ? " (path offline)" : "");

		if (queue_dying) {

			atomic_inc(&m->pg_init_in_progress);

			activate_or_offline_path(pgpath);

			return DM_MAPIO_REQUEUE;

		}

		return DM_MAPIO_DELAY_REQUEUE;

	}

	clone->bio = clone->biotail = NULL;