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Commit c18a1e09 authored by Ming Lei's avatar Ming Lei Committed by Shaohua Li
Browse files

block: introduce bio_clone_bioset_partial() 



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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJens Axboe <axboe@fb.com>
Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 26483819

block/bio.c

+48 −13
Original line number Diff line number Diff line
@@ -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

include/linux/bio.h

+9 −2
Original line number Diff line number Diff line
@@ -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;