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Commit c186794d authored by Mike Snitzer's avatar Mike Snitzer Committed by Jens Axboe
Browse files

block: share request flush fields with elevator_private 



Flush requests are never put on the IO scheduler.  Convert request
structure's elevator_private* into an array and have the flush fields
share a union with it.

Reclaim the space lost in 'struct request' by moving 'completion_data'
back in the union with 'rb_node'.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 9d5a4e94

block/cfq-iosched.c

+9 −9
Original line number Diff line number Diff line
@@ -54,9 +54,9 @@ static const int cfq_hist_divisor = 4; 
#define CFQQ_SEEKY(cfqq)	(hweight32(cfqq->seek_history) > 32/8)



#define RQ_CIC(rq)		\

	((struct cfq_io_context *) (rq)->elevator_private)

#define RQ_CFQQ(rq)		(struct cfq_queue *) ((rq)->elevator_private2)

#define RQ_CFQG(rq)		(struct cfq_group *) ((rq)->elevator_private3)

	((struct cfq_io_context *) (rq)->elevator_private[0])

#define RQ_CFQQ(rq)		(struct cfq_queue *) ((rq)->elevator_private[1])

#define RQ_CFQG(rq)		(struct cfq_group *) ((rq)->elevator_private[2])



static struct kmem_cache *cfq_pool;

static struct kmem_cache *cfq_ioc_pool;
@@ -3589,12 +3589,12 @@ static void cfq_put_request(struct request *rq) 


		put_io_context(RQ_CIC(rq)->ioc);



		rq->elevator_private = NULL;

		rq->elevator_private2 = NULL;

		rq->elevator_private[0] = NULL;

		rq->elevator_private[1] = NULL;



		/* Put down rq reference on cfqg */

		cfq_put_cfqg(RQ_CFQG(rq));

		rq->elevator_private3 = NULL;

		rq->elevator_private[2] = NULL;



		cfq_put_queue(cfqq);

	}
@@ -3685,9 +3685,9 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 


	spin_unlock_irqrestore(q->queue_lock, flags);



	rq->elevator_private = cic;

	rq->elevator_private2 = cfqq;

	rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);

	rq->elevator_private[0] = cic;

	rq->elevator_private[1] = cfqq;

	rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);

	return 0;



queue_fail:

block/elevator.c

+1 −1
Original line number Diff line number Diff line
@@ -764,7 +764,7 @@ int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 
	if (e->ops->elevator_set_req_fn)

		return e->ops->elevator_set_req_fn(q, rq, gfp_mask);



	rq->elevator_private = NULL;

	rq->elevator_private[0] = NULL;

	return 0;

}

include/linux/blkdev.h

+12 −11
Original line number Diff line number Diff line
@@ -99,25 +99,26 @@ struct request { 
	/*

	 * The rb_node is only used inside the io scheduler, requests

	 * are pruned when moved to the dispatch queue. So let the

	 * flush fields share space with the rb_node.

	 * completion_data share space with the rb_node.

	 */

	union {

		struct rb_node rb_node;	/* sort/lookup */

		struct {

			unsigned int			seq;

			struct list_head		list;

		} flush;

	};



		void *completion_data;

	};



	/*

	 * Three pointers are available for the IO schedulers, if they need

	 * more they have to dynamically allocate it.

	 * more they have to dynamically allocate it.  Flush requests are

	 * never put on the IO scheduler. So let the flush fields share

	 * space with the three elevator_private pointers.

	 */

	void *elevator_private;

	void *elevator_private2;

	void *elevator_private3;

	union {

		void *elevator_private[3];

		struct {

			unsigned int		seq;

			struct list_head	list;

		} flush;

	};



	struct gendisk *rq_disk;

	unsigned long start_time;