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Commit 2fb98e84 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: implement request_queue->dma_drain_needed 



Draining shouldn't be done for commands where overflow may indicate
data integrity issues.  Add dma_drain_needed callback to
request_queue.  Drain buffer is appened iff this function returns
non-zero.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 6b00769f

block/blk-merge.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -220,7 +220,7 @@ new_segment: 
		bvprv = bvec;

		bvprv = bvec;

	} /* segments in rq */

	} /* segments in rq */





	if (q->dma_drain_size) {

	if (q->dma_drain_size && q->dma_drain_needed(rq)) {

		sg->page_link &= ~0x02;

		sg->page_link &= ~0x02;

		sg = sg_next(sg);

		sg = sg_next(sg);

		sg_set_page(sg, virt_to_page(q->dma_drain_buffer),

		sg_set_page(sg, virt_to_page(q->dma_drain_buffer),

block/blk-settings.c

+5 −2
Original line number Original line Diff line number Diff line
@@ -296,6 +296,7 @@ EXPORT_SYMBOL(blk_queue_stack_limits); 
 * blk_queue_dma_drain - Set up a drain buffer for excess dma.

 * blk_queue_dma_drain - Set up a drain buffer for excess dma.

 *

 *

 * @q:  the request queue for the device

 * @q:  the request queue for the device

 * @dma_drain_needed: fn which returns non-zero if drain is necessary

 * @buf:	physically contiguous buffer

 * @buf:	physically contiguous buffer

 * @size:	size of the buffer in bytes

 * @size:	size of the buffer in bytes

 *

 *
@@ -315,14 +316,16 @@ EXPORT_SYMBOL(blk_queue_stack_limits); 
 * device can support otherwise there won't be room for the drain

 * device can support otherwise there won't be room for the drain

 * buffer.

 * buffer.

 */

 */

int blk_queue_dma_drain(struct request_queue *q, void *buf,

extern int blk_queue_dma_drain(struct request_queue *q,

				unsigned int size)

			       dma_drain_needed_fn *dma_drain_needed,

			       void *buf, unsigned int size)

{

{

	if (q->max_hw_segments < 2 || q->max_phys_segments < 2)

	if (q->max_hw_segments < 2 || q->max_phys_segments < 2)

		return -EINVAL;

		return -EINVAL;

	/* make room for appending the drain */

	/* make room for appending the drain */

	--q->max_hw_segments;

	--q->max_hw_segments;

	--q->max_phys_segments;

	--q->max_phys_segments;

	q->dma_drain_needed = dma_drain_needed;

	q->dma_drain_buffer = buf;

	q->dma_drain_buffer = buf;

	q->dma_drain_size = size;

	q->dma_drain_size = size;

include/linux/blkdev.h

+5 −2
Original line number Original line Diff line number Diff line
@@ -259,6 +259,7 @@ struct bio_vec; 
typedef int (merge_bvec_fn) (struct request_queue *, struct bio *, struct bio_vec *);

typedef int (merge_bvec_fn) (struct request_queue *, struct bio *, struct bio_vec *);

typedef void (prepare_flush_fn) (struct request_queue *, struct request *);

typedef void (prepare_flush_fn) (struct request_queue *, struct request *);

typedef void (softirq_done_fn)(struct request *);

typedef void (softirq_done_fn)(struct request *);

typedef int (dma_drain_needed_fn)(struct request *);





enum blk_queue_state {

enum blk_queue_state {

	Queue_down,

	Queue_down,
@@ -295,6 +296,7 @@ struct request_queue 
	merge_bvec_fn		*merge_bvec_fn;

	merge_bvec_fn		*merge_bvec_fn;

	prepare_flush_fn	*prepare_flush_fn;

	prepare_flush_fn	*prepare_flush_fn;

	softirq_done_fn		*softirq_done_fn;

	softirq_done_fn		*softirq_done_fn;

	dma_drain_needed_fn	*dma_drain_needed;





	/*

	/*

	 * Dispatch queue sorting

	 * Dispatch queue sorting
@@ -699,8 +701,9 @@ extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short); 
extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);

extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);

extern void blk_queue_hardsect_size(struct request_queue *, unsigned short);

extern void blk_queue_hardsect_size(struct request_queue *, unsigned short);

extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);

extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);

extern int blk_queue_dma_drain(struct request_queue *q, void *buf,

extern int blk_queue_dma_drain(struct request_queue *q,

			       unsigned int size);

			       dma_drain_needed_fn *dma_drain_needed,

			       void *buf, unsigned int size);

extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);

extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);

extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);

extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);

extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);

extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);