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Commit 6f880285 authored by Ming Lei's avatar Ming Lei Committed by Shaohua Li
Browse files

block: introduce bio_copy_data_partial 



Turns out we can use bio_copy_data in raid1's write behind,
and we can make alloc_behind_pages() more clean/efficient,
but we need to partial version of bio_copy_data().

Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Reviewed-by: default avatarJens Axboe <axboe@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 60928a91

block/bio.c

+47 −13
Original line number Diff line number Diff line
@@ -1025,19 +1025,8 @@ int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask) 
}

EXPORT_SYMBOL(bio_alloc_pages);



/**

 * bio_copy_data - copy contents of data buffers from one chain of bios to

 * another

 * @src: source bio list

 * @dst: destination bio list

 *

 * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats

 * @src and @dst as linked lists of bios.

 *

 * Stops when it reaches the end of either @src or @dst - that is, copies

 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).

 */

void bio_copy_data(struct bio *dst, struct bio *src)

static void __bio_copy_data(struct bio *dst, struct bio *src,

			    int offset, int size)

{

	struct bvec_iter src_iter, dst_iter;

	struct bio_vec src_bv, dst_bv;
@@ -1047,6 +1036,12 @@ void bio_copy_data(struct bio *dst, struct bio *src) 
	src_iter = src->bi_iter;

	dst_iter = dst->bi_iter;



	/* for supporting partial copy */

	if (offset || size != src->bi_iter.bi_size) {

		bio_advance_iter(src, &src_iter, offset);

		src_iter.bi_size = size;

	}



	while (1) {

		if (!src_iter.bi_size) {

			src = src->bi_next;
@@ -1083,8 +1078,47 @@ void bio_copy_data(struct bio *dst, struct bio *src) 
		bio_advance_iter(dst, &dst_iter, bytes);

	}

}



/**

 * bio_copy_data - copy contents of data buffers from one chain of bios to

 * another

 * @src: source bio list

 * @dst: destination bio list

 *

 * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats

 * @src and @dst as linked lists of bios.

 *

 * Stops when it reaches the end of either @src or @dst - that is, copies

 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).

 */

void bio_copy_data(struct bio *dst, struct bio *src)

{

	__bio_copy_data(dst, src, 0, src->bi_iter.bi_size);

}

EXPORT_SYMBOL(bio_copy_data);



/**

 * bio_copy_data_partial - copy partial contents of data buffers from one

 * chain of bios to another

 * @dst: destination bio list

 * @src: source bio list

 * @offset: starting copy from the offset

 * @size: how many bytes to copy

 *

 * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats

 * @src and @dst as linked lists of bios.

 *

 * Stops when it reaches the end of either @src or @dst - that is, copies

 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).

 */

void bio_copy_data_partial(struct bio *dst, struct bio *src,

			   int offset, int size)

{

	__bio_copy_data(dst, src, offset, size);



}

EXPORT_SYMBOL(bio_copy_data_partial);



struct bio_map_data {

	int is_our_pages;

	struct iov_iter iter;

include/linux/bio.h

+2 −0
Original line number Diff line number Diff line
@@ -468,6 +468,8 @@ static inline void bio_flush_dcache_pages(struct bio *bi) 
#endif



extern void bio_copy_data(struct bio *dst, struct bio *src);

extern void bio_copy_data_partial(struct bio *dst, struct bio *src,

				  int offset, int size);

extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);

extern void bio_free_pages(struct bio *bio);