Commit dd831006 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: misc cleanups in barrier code 



Make the following cleanups in preparation of barrier/flush update.

* blk_do_ordered() declaration is moved from include/linux/blkdev.h to
  block/blk.h.

* blk_do_ordered() now returns pointer to struct request, with %NULL
  meaning "try the next request" and ERR_PTR(-EAGAIN) "try again
  later".  The third case will be dropped with further changes.

* In the initialization of proxy barrier request, data direction is
  already set by init_request_from_bio().  Drop unnecessary explicit
  REQ_WRITE setting and move init_request_from_bio() above REQ_FUA
  flag setting.

* add_request() is collapsed into __make_request().

These changes don't make any functional difference.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 9cbbdca4

block/blk-barrier.c

+14 −18
Original line number Diff line number Diff line
@@ -110,9 +110,9 @@ static void queue_flush(struct request_queue *q, unsigned which) 
	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);

}



static inline bool start_ordered(struct request_queue *q, struct request **rqp)

static inline struct request *start_ordered(struct request_queue *q,

					    struct request *rq)

{

	struct request *rq = *rqp;

	unsigned skip = 0;



	q->orderr = 0;
@@ -149,11 +149,9 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp) 


		/* initialize proxy request and queue it */

		blk_rq_init(q, rq);

		if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)

			rq->cmd_flags |= REQ_WRITE;

		init_request_from_bio(rq, q->orig_bar_rq->bio);

		if (q->ordered & QUEUE_ORDERED_DO_FUA)

			rq->cmd_flags |= REQ_FUA;

		init_request_from_bio(rq, q->orig_bar_rq->bio);

		rq->end_io = bar_end_io;



		elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
@@ -171,27 +169,26 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp) 
	else

		skip |= QUEUE_ORDSEQ_DRAIN;



	*rqp = rq;



	/*

	 * Complete skipped sequences.  If whole sequence is complete,

	 * return false to tell elevator that this request is gone.

	 * return %NULL to tell elevator that this request is gone.

	 */

	return !blk_ordered_complete_seq(q, skip, 0);

	if (blk_ordered_complete_seq(q, skip, 0))

		rq = NULL;

	return rq;

}



bool blk_do_ordered(struct request_queue *q, struct request **rqp)

struct request *blk_do_ordered(struct request_queue *q, struct request *rq)

{

	struct request *rq = *rqp;

	const int is_barrier = rq->cmd_type == REQ_TYPE_FS &&

				(rq->cmd_flags & REQ_HARDBARRIER);



	if (!q->ordseq) {

		if (!is_barrier)

			return true;

			return rq;



		if (q->next_ordered != QUEUE_ORDERED_NONE)

			return start_ordered(q, rqp);

			return start_ordered(q, rq);

		else {

			/*

			 * Queue ordering not supported.  Terminate
@@ -199,8 +196,7 @@ bool blk_do_ordered(struct request_queue *q, struct request **rqp) 
			 */

			blk_dequeue_request(rq);

			__blk_end_request_all(rq, -EOPNOTSUPP);

			*rqp = NULL;

			return false;

			return NULL;

		}

	}
@@ -211,14 +207,14 @@ bool blk_do_ordered(struct request_queue *q, struct request **rqp) 
	/* Special requests are not subject to ordering rules. */

	if (rq->cmd_type != REQ_TYPE_FS &&

	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)

		return true;

		return rq;



	/* Ordered by draining.  Wait for turn. */

	WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));

	if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))

		*rqp = NULL;

		rq = ERR_PTR(-EAGAIN);



	return true;

	return rq;

}



static void bio_end_empty_barrier(struct bio *bio, int err)

block/blk-core.c

+4 −17
Original line number Diff line number Diff line
@@ -1037,22 +1037,6 @@ void blk_insert_request(struct request_queue *q, struct request *rq, 
}

EXPORT_SYMBOL(blk_insert_request);



/*

 * add-request adds a request to the linked list.

 * queue lock is held and interrupts disabled, as we muck with the

 * request queue list.

 */

static inline void add_request(struct request_queue *q, struct request *req)

{

	drive_stat_acct(req, 1);



	/*

	 * elevator indicated where it wants this request to be

	 * inserted at elevator_merge time

	 */

	__elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);

}



static void part_round_stats_single(int cpu, struct hd_struct *part,

				    unsigned long now)

{
@@ -1316,7 +1300,10 @@ get_rq: 
		req->cpu = blk_cpu_to_group(smp_processor_id());

	if (queue_should_plug(q) && elv_queue_empty(q))

		blk_plug_device(q);

	add_request(q, req);



	/* insert the request into the elevator */

	drive_stat_acct(req, 1);

	__elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);

out:

	if (unplug || !queue_should_plug(q))

		__generic_unplug_device(q);

block/blk.h

+5 −2
Original line number Diff line number Diff line
@@ -51,6 +51,8 @@ static inline void blk_clear_rq_complete(struct request *rq) 
 */

#define ELV_ON_HASH(rq)		(!hlist_unhashed(&(rq)->hash))



struct request *blk_do_ordered(struct request_queue *q, struct request *rq);



static inline struct request *__elv_next_request(struct request_queue *q)

{

	struct request *rq;
@@ -58,8 +60,9 @@ static inline struct request *__elv_next_request(struct request_queue *q) 
	while (1) {

		while (!list_empty(&q->queue_head)) {

			rq = list_entry_rq(q->queue_head.next);

			if (blk_do_ordered(q, &rq))

				return rq;

			rq = blk_do_ordered(q, rq);

			if (rq)

				return !IS_ERR(rq) ? rq : NULL;

		}



		if (!q->elevator->ops->elevator_dispatch_fn(q, 0))

include/linux/blkdev.h

+0 −1
Original line number Diff line number Diff line
@@ -869,7 +869,6 @@ extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *); 
extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);

extern void blk_queue_flush(struct request_queue *q, unsigned int flush);

extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);

extern bool blk_do_ordered(struct request_queue *, struct request **);

extern unsigned blk_ordered_cur_seq(struct request_queue *);

extern unsigned blk_ordered_req_seq(struct request *);

extern bool blk_ordered_complete_seq(struct request_queue *, unsigned, int);

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