dm mpath: fix missing call of path selector type->end_io
After commit396eaf21ee
("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 commit396eaf21ee
, 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:396eaf21ee
("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>
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parent
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@ -544,8 +544,23 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
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return DM_MAPIO_REMAPPED;
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}
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static void multipath_release_clone(struct request *clone)
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static void multipath_release_clone(struct request *clone,
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union map_info *map_context)
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{
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if (unlikely(map_context)) {
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/*
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* non-NULL map_context means caller is still map
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* method; must undo multipath_clone_and_map()
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*/
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struct dm_mpath_io *mpio = get_mpio(map_context);
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struct pgpath *pgpath = mpio->pgpath;
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if (pgpath && pgpath->pg->ps.type->end_io)
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pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
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&pgpath->path,
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mpio->nr_bytes);
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}
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blk_put_request(clone);
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}
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@ -168,7 +168,7 @@ static void dm_end_request(struct request *clone, blk_status_t error)
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struct request *rq = tio->orig;
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blk_rq_unprep_clone(clone);
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tio->ti->type->release_clone_rq(clone);
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tio->ti->type->release_clone_rq(clone, NULL);
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rq_end_stats(md, rq);
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blk_mq_end_request(rq, error);
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@ -201,7 +201,7 @@ static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_
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rq_end_stats(md, rq);
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if (tio->clone) {
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blk_rq_unprep_clone(tio->clone);
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tio->ti->type->release_clone_rq(tio->clone);
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tio->ti->type->release_clone_rq(tio->clone, NULL);
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}
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dm_mq_delay_requeue_request(rq, delay_ms);
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@ -398,7 +398,7 @@ static int map_request(struct dm_rq_target_io *tio)
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case DM_MAPIO_REMAPPED:
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if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
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/* -ENOMEM */
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ti->type->release_clone_rq(clone);
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ti->type->release_clone_rq(clone, &tio->info);
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return DM_MAPIO_REQUEUE;
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}
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@ -408,7 +408,7 @@ static int map_request(struct dm_rq_target_io *tio)
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ret = dm_dispatch_clone_request(clone, rq);
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if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
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blk_rq_unprep_clone(clone);
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tio->ti->type->release_clone_rq(clone);
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tio->ti->type->release_clone_rq(clone, &tio->info);
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tio->clone = NULL;
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return DM_MAPIO_REQUEUE;
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}
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@ -136,7 +136,8 @@ static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq,
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return DM_MAPIO_KILL;
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}
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static void io_err_release_clone_rq(struct request *clone)
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static void io_err_release_clone_rq(struct request *clone,
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union map_info *map_context)
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{
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}
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@ -62,7 +62,8 @@ typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
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struct request *rq,
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union map_info *map_context,
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struct request **clone);
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typedef void (*dm_release_clone_request_fn) (struct request *clone);
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typedef void (*dm_release_clone_request_fn) (struct request *clone,
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union map_info *map_context);
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/*
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* Returns:
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