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Commit 87904074 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Jens Axboe
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block: add blk_rq_aligned helper function 



This adds blk_rq_aligned helper function to see if alignment and
padding requirement is satisfied for DMA transfer. This also converts
blk_rq_map_kern and __blk_rq_map_user to use the helper function.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 4d8ab62e

block/blk-map.c

+2 −10
Original line number Diff line number Diff line
@@ -45,7 +45,6 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, 
			     unsigned int len, gfp_t gfp_mask)

{

	unsigned long uaddr;

	unsigned int alignment;

	struct bio *bio, *orig_bio;

	int reading, ret;
@@ -56,8 +55,7 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, 
	 * direct dma. else, set up kernel bounce buffers

	 */

	uaddr = (unsigned long) ubuf;

	alignment = queue_dma_alignment(q) | q->dma_pad_mask;

	if (!(uaddr & alignment) && !(len & alignment) && !map_data)

	if (blk_rq_aligned(q, ubuf, len) && !map_data)

		bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);

	else

		bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);
@@ -274,8 +272,6 @@ EXPORT_SYMBOL(blk_rq_unmap_user); 
int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,

		    unsigned int len, gfp_t gfp_mask)

{

	unsigned long kaddr;

	unsigned int alignment;

	int reading = rq_data_dir(rq) == READ;

	int do_copy = 0;

	struct bio *bio;
@@ -285,11 +281,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 
	if (!len || !kbuf)

		return -EINVAL;



	kaddr = (unsigned long)kbuf;

	alignment = queue_dma_alignment(q) | q->dma_pad_mask;

	do_copy = ((kaddr & alignment) || (len & alignment) ||

		   object_is_on_stack(kbuf));



	do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf);

	if (do_copy)

		bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);

	else

include/linux/blkdev.h

+7 −0
Original line number Diff line number Diff line
@@ -899,6 +899,13 @@ static inline int queue_dma_alignment(struct request_queue *q) 
	return q ? q->dma_alignment : 511;

}



static inline int blk_rq_aligned(struct request_queue *q, void *addr,

				 unsigned int len)

{

	unsigned int alignment = queue_dma_alignment(q) | q->dma_pad_mask;

	return !((unsigned long)addr & alignment) && !(len & alignment);

}



/* assumes size > 256 */

static inline unsigned int blksize_bits(unsigned int size)

{