From: Yufen Yu yuyufen@huawei.com
[ Upstream commit 5de719e3d01b4abe0de0d7b857148a880ff2a90b ]
After commit 396eaf21ee17 ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback"), map_request() will requeue the tio when issued clone request return BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE.
Thus, if device driver status is error, a tio may be requeued multiple times until the return value is not DM_MAPIO_REQUEUE. That means type->start_io may be called multiple times, while type->end_io is only called when IO complete.
In fact, even without commit 396eaf21ee17, setup_clone() failure can also cause tio requeue and associated missed call to type->end_io.
The service-time path selector selects path based on in_flight_size, which is increased by st_start_io() and decreased by st_end_io(). Missed calls to st_end_io() can lead to in_flight_size count error and will cause the selector to make the wrong choice. In addition, queue-length path selector will also be affected.
To fix the problem, call type->end_io in ->release_clone_rq before tio requeue. map_info is passed to ->release_clone_rq() for map_request() error path that result in requeue.
Fixes: 396eaf21ee17 ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback") Cc: stable@vger.kernl.org Signed-off-by: Yufen Yu yuyufen@huawei.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-mpath.c | 17 ++++++++++++++++- drivers/md/dm-rq.c | 8 ++++---- drivers/md/dm-target.c | 3 ++- include/linux/device-mapper.h | 3 ++- 4 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index baa966e2778c0..481e54ded9dc7 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -554,8 +554,23 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, return DM_MAPIO_REMAPPED; }
-static void multipath_release_clone(struct request *clone) +static void multipath_release_clone(struct request *clone, + union map_info *map_context) { + if (unlikely(map_context)) { + /* + * non-NULL map_context means caller is still map + * method; must undo multipath_clone_and_map() + */ + struct dm_mpath_io *mpio = get_mpio(map_context); + struct pgpath *pgpath = mpio->pgpath; + + if (pgpath && pgpath->pg->ps.type->end_io) + pgpath->pg->ps.type->end_io(&pgpath->pg->ps, + &pgpath->path, + mpio->nr_bytes); + } + blk_put_request(clone); }
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 264b84e274aac..17c6a73c536c6 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -219,7 +219,7 @@ static void dm_end_request(struct request *clone, blk_status_t error) struct request *rq = tio->orig;
blk_rq_unprep_clone(clone); - tio->ti->type->release_clone_rq(clone); + tio->ti->type->release_clone_rq(clone, NULL);
rq_end_stats(md, rq); if (!rq->q->mq_ops) @@ -270,7 +270,7 @@ static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_ rq_end_stats(md, rq); if (tio->clone) { blk_rq_unprep_clone(tio->clone); - tio->ti->type->release_clone_rq(tio->clone); + tio->ti->type->release_clone_rq(tio->clone, NULL); }
if (!rq->q->mq_ops) @@ -495,7 +495,7 @@ static int map_request(struct dm_rq_target_io *tio) case DM_MAPIO_REMAPPED: if (setup_clone(clone, rq, tio, GFP_ATOMIC)) { /* -ENOMEM */ - ti->type->release_clone_rq(clone); + ti->type->release_clone_rq(clone, &tio->info); return DM_MAPIO_REQUEUE; }
@@ -505,7 +505,7 @@ static int map_request(struct dm_rq_target_io *tio) ret = dm_dispatch_clone_request(clone, rq); if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) { blk_rq_unprep_clone(clone); - tio->ti->type->release_clone_rq(clone); + tio->ti->type->release_clone_rq(clone, &tio->info); tio->clone = NULL; if (!rq->q->mq_ops) r = DM_MAPIO_DELAY_REQUEUE; diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c index 314d17ca64668..64dd0b34fcf49 100644 --- a/drivers/md/dm-target.c +++ b/drivers/md/dm-target.c @@ -136,7 +136,8 @@ static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq, return DM_MAPIO_KILL; }
-static void io_err_release_clone_rq(struct request *clone) +static void io_err_release_clone_rq(struct request *clone, + union map_info *map_context) { }
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index bef2e36c01b4b..91f9f95ad5066 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -62,7 +62,8 @@ typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti, struct request *rq, union map_info *map_context, struct request **clone); -typedef void (*dm_release_clone_request_fn) (struct request *clone); +typedef void (*dm_release_clone_request_fn) (struct request *clone, + union map_info *map_context);
/* * Returns: