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block: introduce bio_copy_data_partial

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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: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
Ming Lei 2017-03-17 00:12:29 +08:00 committed by Shaohua Li
parent 60928a91b0
commit 6f8802852f
2 changed files with 49 additions and 13 deletions
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60
block/bio.c
View file

@ -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;

2
include/linux/bio.h
View file

@ -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);