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Commit c6d600c6 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq: refactor request insertion/merging 



Refactor the logic around adding a new bio to a software queue,
so we nest the ctx->lock where we really need it (merge and
insertion) and don't hold it when we don't (init and IO start
accounting).

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 98bc1f27

block/blk-mq.c

+15 −7
Original line number Diff line number Diff line
@@ -1037,17 +1037,25 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio) 
		}

	}



	spin_lock(&ctx->lock);

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

		init_request_from_bio(rq, bio);



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

	    blk_mq_attempt_merge(q, ctx, bio))

		__blk_mq_free_request(hctx, ctx, rq);

	else {

		blk_mq_bio_to_request(rq, bio);

		spin_lock(&ctx->lock);

insert_rq:

		__blk_mq_insert_request(hctx, rq, false);

		spin_unlock(&ctx->lock);

		blk_account_io_start(rq, 1);

	} else {

		spin_lock(&ctx->lock);

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

			init_request_from_bio(rq, bio);

			goto insert_rq;

		}



		spin_unlock(&ctx->lock);

		__blk_mq_free_request(hctx, ctx, rq);

	}





	/*

	 * For a SYNC request, send it to the hardware immediately. For an