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block: don't dereference request after flush insertion 

We could have a race here, where the request gets freed before we call
into blk_mq_run_hw_queue(). If this happens, we cannot rely on the state
of the request.

Grab the hardware context before inserting the flush.

Fixes: 0f38d76646 ("blk-mq: cleanup blk_mq_submit_bio")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-10-16 07:34:49 -06:00
parent 0f38d76646
commit 4a60f360a5
1 changed files with 2 additions and 1 deletions
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3
block/blk-mq.c
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@ -2284,9 +2284,10 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
}
if (unlikely(is_flush_fua)) {
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
/* Bypass scheduler for flush requests */
blk_insert_flush(rq);
blk_mq_run_hw_queue(rq->mq_hctx, true);
blk_mq_run_hw_queue(hctx, true);
} else if (plug && (q->nr_hw_queues == 1 ||
blk_mq_is_shared_tags(rq->mq_hctx->flags) ||
q->mq_ops->commit_rqs || !blk_queue_nonrot(q))) {