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block: introduce bio_clone_bioset_partial()

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md still need bio clone(not the fast version) for behind write,
and it is more efficient to use bio_clone_bioset_partial().

The idea is simple and just copy the bvecs range specified from
parameters.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
Ming Lei 2017-02-14 23:28:59 +08:00 committed by Shaohua Li
parent 26483819f8
commit c18a1e0900
2 changed files with 57 additions and 15 deletions
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61
block/bio.c
View file

@ -625,21 +625,20 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
}
EXPORT_SYMBOL(bio_clone_fast);
/**
* bio_clone_bioset - clone a bio
* @bio_src: bio to clone
* @gfp_mask: allocation priority
* @bs: bio_set to allocate from
*
* Clone bio. Caller will own the returned bio, but not the actual data it
* points to. Reference count of returned bio will be one.
*/
struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
struct bio_set *bs)
static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
struct bio_set *bs, int offset,
int size)
{
struct bvec_iter iter;
struct bio_vec bv;
struct bio *bio;
struct bvec_iter iter_src = bio_src->bi_iter;
/* for supporting partial clone */
if (offset || size != bio_src->bi_iter.bi_size) {
bio_advance_iter(bio_src, &iter_src, offset);
iter_src.bi_size = size;
}
/*
* Pre immutable biovecs, __bio_clone() used to just do a memcpy from
@ -663,7 +662,8 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
* __bio_clone_fast() anyways.
*/
bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
bio = bio_alloc_bioset(gfp_mask, __bio_segments(bio_src,
&iter_src), bs);
if (!bio)
return NULL;
bio->bi_bdev = bio_src->bi_bdev;
@ -680,7 +680,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
break;
default:
bio_for_each_segment(bv, bio_src, iter)
__bio_for_each_segment(bv, bio_src, iter, iter_src)
bio->bi_io_vec[bio->bi_vcnt++] = bv;
break;
}
@ -699,8 +699,43 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
return bio;
}
/**
* bio_clone_bioset - clone a bio
* @bio_src: bio to clone
* @gfp_mask: allocation priority
* @bs: bio_set to allocate from
*
* Clone bio. Caller will own the returned bio, but not the actual data it
* points to. Reference count of returned bio will be one.
*/
struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
struct bio_set *bs)
{
return __bio_clone_bioset(bio_src, gfp_mask, bs, 0,
bio_src->bi_iter.bi_size);
}
EXPORT_SYMBOL(bio_clone_bioset);
/**
* bio_clone_bioset_partial - clone a partial bio
* @bio_src: bio to clone
* @gfp_mask: allocation priority
* @bs: bio_set to allocate from
* @offset: cloned starting from the offset
* @size: size for the cloned bio
*
* Clone bio. Caller will own the returned bio, but not the actual data it
* points to. Reference count of returned bio will be one.
*/
struct bio *bio_clone_bioset_partial(struct bio *bio_src, gfp_t gfp_mask,
struct bio_set *bs, int offset,
int size)
{
return __bio_clone_bioset(bio_src, gfp_mask, bs, offset, size);
}
EXPORT_SYMBOL(bio_clone_bioset_partial);
/**
* bio_add_pc_page - attempt to add page to bio
* @q: the target queue

11
include/linux/bio.h
View file

@ -183,7 +183,7 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
static inline unsigned bio_segments(struct bio *bio)
static inline unsigned __bio_segments(struct bio *bio, struct bvec_iter *bvec)
{
unsigned segs = 0;
struct bio_vec bv;
@ -205,12 +205,17 @@ static inline unsigned bio_segments(struct bio *bio)
break;
}
bio_for_each_segment(bv, bio, iter)
__bio_for_each_segment(bv, bio, iter, *bvec)
segs++;
return segs;
}
static inline unsigned bio_segments(struct bio *bio)
{
return __bio_segments(bio, &bio->bi_iter);
}
/*
* get a reference to a bio, so it won't disappear. the intended use is
* something like:
@ -384,6 +389,8 @@ extern void bio_put(struct bio *);
extern void __bio_clone_fast(struct bio *, struct bio *);
extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
extern struct bio *bio_clone_bioset_partial(struct bio *, gfp_t,
struct bio_set *, int, int);
extern struct bio_set *fs_bio_set;