block: simplify empty barrier implementation (58eea927) · Commits · 戴 / test

block/blk-barrier.c

+10 −6

Original line number	Original line	Diff line number	Diff line
	@@ -162,6 +162,14 @@ static inline bool start_ordered(struct request_queue q, struct request *rqp)
	q->ordered = q->next_ordered;		q->ordered = q->next_ordered;
	q->ordseq \|= QUEUE_ORDSEQ_STARTED;		q->ordseq \|= QUEUE_ORDSEQ_STARTED;

			/*
			* For an empty barrier, there's no actual BAR request, which
			* in turn makes POSTFLUSH unnecessary. Mask them off.
			*/
			if (!rq->hard_nr_sectors)
			q->ordered &= ~(QUEUE_ORDERED_DO_BAR \|
			QUEUE_ORDERED_DO_POSTFLUSH);

	/* stash away the original request */		/* stash away the original request */
	elv_dequeue_request(q, rq);		elv_dequeue_request(q, rq);
	q->orig_bar_rq = rq;		q->orig_bar_rq = rq;
	@@ -171,13 +179,9 @@ static inline bool start_ordered(struct request_queue q, struct request *rqp)
	* Queue ordered sequence. As we stack them at the head, we		* Queue ordered sequence. As we stack them at the head, we
	* need to queue in reverse order. Note that we rely on that		* need to queue in reverse order. Note that we rely on that
	* no fs request uses ELEVATOR_INSERT_FRONT and thus no fs		* no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
	* request gets inbetween ordered sequence. If this request is		* request gets inbetween ordered sequence.
	* an empty barrier, we don't need to do a postflush ever since
	* there will be no data written between the pre and post flush.
	* Hence a single flush will suffice.
	*/		*/
	if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) &&		if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) {
	!blk_empty_barrier(q->orig_bar_rq)) {
	queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);		queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
	rq = &q->post_flush_rq;		rq = &q->post_flush_rq;
	} else		} else

block/elevator.c

+0 −8

Original line number	Original line	Diff line number	Diff line
	@@ -755,14 +755,6 @@ struct request elv_next_request(struct request_queue q)
	int ret;		int ret;

	while ((rq = __elv_next_request(q)) != NULL) {		while ((rq = __elv_next_request(q)) != NULL) {
	/*
	* Kill the empty barrier place holder, the driver must
	* not ever see it.
	*/
	if (blk_empty_barrier(rq)) {
	__blk_end_request(rq, 0, blk_rq_bytes(rq));
	continue;
	}
	if (!(rq->cmd_flags & REQ_STARTED)) {		if (!(rq->cmd_flags & REQ_STARTED)) {
	/*		/*
	* This is the first time the device driver		* This is the first time the device driver

include/linux/blkdev.h

+0 −1

Original line number	Original line	Diff line number	Diff line
	@@ -596,7 +596,6 @@ enum {
	#define blk_fua_rq(rq) ((rq)->cmd_flags & REQ_FUA)		#define blk_fua_rq(rq) ((rq)->cmd_flags & REQ_FUA)
	#define blk_discard_rq(rq) ((rq)->cmd_flags & REQ_DISCARD)		#define blk_discard_rq(rq) ((rq)->cmd_flags & REQ_DISCARD)
	#define blk_bidi_rq(rq) ((rq)->next_rq != NULL)		#define blk_bidi_rq(rq) ((rq)->next_rq != NULL)
	#define blk_empty_barrier(rq) (blk_barrier_rq(rq) && blk_fs_request(rq) && !(rq)->hard_nr_sectors)
	/* rq->queuelist of dequeued request must be list_empty() */		/* rq->queuelist of dequeued request must be list_empty() */
	#define blk_queued_rq(rq) (!list_empty(&(rq)->queuelist))		#define blk_queued_rq(rq) (!list_empty(&(rq)->queuelist))

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