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Commit 30e9656c authored by Tejun Heo's avatar Tejun Heo Committed by Linus Torvalds
Browse files

[PATCH] block: implement elv_insert and use it (fix ordcolor flipping bug) 



q->ordcolor must only be flipped on initial queueing of a hardbarrier
request.

Constructing ordered sequence and requeueing used to pass through
__elv_add_request() which flips q->ordcolor when it sees a barrier
request.

This patch separates out elv_insert() from __elv_add_request() and uses
elv_insert() when constructing ordered sequence and requeueing.
elv_insert() inserts the given request at the specified position and
does nothing else.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Acked-by: default avatarJens Axboe <axboe@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e5ea0a9f

block/elevator.c

+38 −32
Original line number Diff line number Diff line
@@ -293,7 +293,7 @@ void elv_requeue_request(request_queue_t *q, struct request *rq) 


	rq->flags &= ~REQ_STARTED;



	__elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE, 0);

	elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);

}



static void elv_drain_elevator(request_queue_t *q)
@@ -310,41 +310,11 @@ static void elv_drain_elevator(request_queue_t *q) 
	}

}



void __elv_add_request(request_queue_t *q, struct request *rq, int where,

		       int plug)

void elv_insert(request_queue_t *q, struct request *rq, int where)

{

	struct list_head *pos;

	unsigned ordseq;



	if (q->ordcolor)

		rq->flags |= REQ_ORDERED_COLOR;



	if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {

		/*

		 * toggle ordered color

		 */

		if (blk_barrier_rq(rq))

			q->ordcolor ^= 1;



		/*

		 * barriers implicitly indicate back insertion

		 */

		if (where == ELEVATOR_INSERT_SORT)

			where = ELEVATOR_INSERT_BACK;



		/*

		 * this request is scheduling boundary, update end_sector

		 */

		if (blk_fs_request(rq)) {

			q->end_sector = rq_end_sector(rq);

			q->boundary_rq = rq;

		}

	} else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)

		where = ELEVATOR_INSERT_BACK;



	if (plug)

		blk_plug_device(q);



	rq->q = q;



	switch (where) {
@@ -425,6 +395,42 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, 
	}

}



void __elv_add_request(request_queue_t *q, struct request *rq, int where,

		       int plug)

{

	if (q->ordcolor)

		rq->flags |= REQ_ORDERED_COLOR;



	if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {

		/*

		 * toggle ordered color

		 */

		if (blk_barrier_rq(rq))

			q->ordcolor ^= 1;



		/*

		 * barriers implicitly indicate back insertion

		 */

		if (where == ELEVATOR_INSERT_SORT)

			where = ELEVATOR_INSERT_BACK;



		/*

		 * this request is scheduling boundary, update

		 * end_sector

		 */

		if (blk_fs_request(rq)) {

			q->end_sector = rq_end_sector(rq);

			q->boundary_rq = rq;

		}

	} else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)

		where = ELEVATOR_INSERT_BACK;



	if (plug)

		blk_plug_device(q);



	elv_insert(q, rq, where);

}



void elv_add_request(request_queue_t *q, struct request *rq, int where,

		     int plug)

{

block/ll_rw_blk.c

+2 −2
Original line number Diff line number Diff line
@@ -454,7 +454,7 @@ static void queue_flush(request_queue_t *q, unsigned which) 
	rq->end_io = end_io;

	q->prepare_flush_fn(q, rq);



	__elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);

	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);

}



static inline struct request *start_ordered(request_queue_t *q,
@@ -490,7 +490,7 @@ static inline struct request *start_ordered(request_queue_t *q, 
	else

		q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;



	__elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);

	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);



	if (q->ordered & QUEUE_ORDERED_PREFLUSH) {

		queue_flush(q, QUEUE_ORDERED_PREFLUSH);

include/linux/elevator.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ struct elevator_queue 
extern void elv_dispatch_sort(request_queue_t *, struct request *);

extern void elv_add_request(request_queue_t *, struct request *, int, int);

extern void __elv_add_request(request_queue_t *, struct request *, int, int);

extern void elv_insert(request_queue_t *, struct request *, int);

extern int elv_merge(request_queue_t *, struct request **, struct bio *);

extern void elv_merge_requests(request_queue_t *, struct request *,

			       struct request *);