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block: ensure we hold a queue reference when using queue limits 

q_usage_counter is the only thing preventing us from the limits changing
under us in __bio_split_to_limits, but blk_mq_submit_bio doesn't hold
it while calling into it.

Move the splitting inside the region where we know we've got a queue
reference. Ideally this could still remain a shared section of code, but
let's keep the fix simple and defer any refactoring here to later.

Reported-by: Christoph Hellwig <hch@lst.de>
Fixes: 900e080752 ("block: move queue enter logic into blk_mq_submit_bio()")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-01-12 09:12:20 -07:00
parent 309ce67414
commit 7b4f36cd22
1 changed files with 10 additions and 6 deletions
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16
block/blk-mq.c
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@ -2964,12 +2964,6 @@ void blk_mq_submit_bio(struct bio *bio)
blk_status_t ret;
bio = blk_queue_bounce(bio, q);
if (bio_may_exceed_limits(bio, &q->limits)) {
bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
if (!bio)
return;
}
bio_set_ioprio(bio);
if (plug) {
@ -2978,6 +2972,11 @@ void blk_mq_submit_bio(struct bio *bio)
rq = NULL;
}
if (rq) {
if (unlikely(bio_may_exceed_limits(bio, &q->limits))) {
bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
if (!bio)
return;
}
if (!bio_integrity_prep(bio))
return;
if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
@ -2988,6 +2987,11 @@ void blk_mq_submit_bio(struct bio *bio)
} else {
if (unlikely(bio_queue_enter(bio)))
return;
if (unlikely(bio_may_exceed_limits(bio, &q->limits))) {
bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
if (!bio)
goto fail;
}
if (!bio_integrity_prep(bio))
goto fail;
}