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dm: fix false warning in free_rq_clone() for unmapped requests 

When stacking request-based dm device on non blk-mq device and
device-mapper target could not map the request (error target is used,
multipath target with all paths down, etc), the WARN_ON_ONCE() in
free_rq_clone() will trigger when it shouldn't.

The warning was added by commit aa6df8d ("dm: fix free_rq_clone() NULL
pointer when requeueing unmapped request").  But free_rq_clone() with
clone->q == NULL is valid usage for the case where
dm_kill_unmapped_request() initiates request cleanup.

Fix this false warning by just removing the WARN_ON -- it only generated
false positives and was never useful in catching the intended case
(completing clone request not being mapped e.g. clone->q being NULL).

Fixes: aa6df8d ("dm: fix free_rq_clone() NULL pointer when requeueing unmapped request")
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2015-05-28 15:12:52 -04:00
parent 45714fbed4
commit e5d8de32cc
1 changed files with 3 additions and 5 deletions
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8
drivers/md/dm.c
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@ -1082,13 +1082,11 @@ static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
dm_put(md);
}
static void free_rq_clone(struct request *clone, bool must_be_mapped)
static void free_rq_clone(struct request *clone)
{
struct dm_rq_target_io *tio = clone->end_io_data;
struct mapped_device *md = tio->md;
WARN_ON_ONCE(must_be_mapped && !clone->q);
blk_rq_unprep_clone(clone);
if (md->type == DM_TYPE_MQ_REQUEST_BASED)
@ -1132,7 +1130,7 @@ static void dm_end_request(struct request *clone, int error)
rq->sense_len = clone->sense_len;
}
free_rq_clone(clone, true);
free_rq_clone(clone);
if (!rq->q->mq_ops)
blk_end_request_all(rq, error);
else
@ -1151,7 +1149,7 @@ static void dm_unprep_request(struct request *rq)
}
if (clone)
free_rq_clone(clone, false);
free_rq_clone(clone);
}
/*