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| author |   Bart Van Assche <bart.vanassche@sandisk.com> | 2017-04-27 10:11:15 -0700 |
|---|---|---|
| committer |   Mike Snitzer <snitzer@redhat.com> | 2017-04-27 17:04:27 -0400 |
| commit | 7083abbbfc4fa706ff72d27d33a5214881979336 (patch) | |
| tree | 2fa2f90642cc55502a2f827620d6fd60a6f3e589 /drivers/md | |
| parent | dm mpath: split and rename activate_path() to prepare for its expanded use (diff) | |
| download | linux-dev-7083abbbfc4fa706ff72d27d33a5214881979336.tar.xz linux-dev-7083abbbfc4fa706ff72d27d33a5214881979336.zip | |
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: Bart 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: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-mpath.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 4b891d9ff349..f3c79f188747 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -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; |