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Commit 274a5843 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq: don't allow merges if turned off for the queue 



blk-mq uses BLK_MQ_F_SHOULD_MERGE, as set by the driver at init time,
to determine whether it should merge IO or not. However, this could
also be disabled by the admin, if merging is switched off through
sysfs. So check the general queue state as well before attempting
to merge IO.

Reported-by: default avatarRob Elliott <Elliott@hp.com>
Tested-by: default avatarRob Elliott <Elliott@hp.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 8a58d1f1

block/blk-mq.c

+9 −3
Original line number Diff line number Diff line
@@ -1068,13 +1068,17 @@ static void blk_mq_bio_to_request(struct request *rq, struct bio *bio) 
		blk_account_io_start(rq, 1);

}



static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)

{

	return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&

		!blk_queue_nomerges(hctx->queue);

}



static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,

					 struct blk_mq_ctx *ctx,

					 struct request *rq, struct bio *bio)

{

	struct request_queue *q = hctx->queue;



	if (!(hctx->flags & BLK_MQ_F_SHOULD_MERGE)) {

	if (!hctx_allow_merges(hctx)) {

		blk_mq_bio_to_request(rq, bio);

		spin_lock(&ctx->lock);

insert_rq:
@@ -1082,6 +1086,8 @@ static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx, 
		spin_unlock(&ctx->lock);

		return false;

	} else {

		struct request_queue *q = hctx->queue;



		spin_lock(&ctx->lock);

		if (!blk_mq_attempt_merge(q, ctx, bio)) {

			blk_mq_bio_to_request(rq, bio);