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: 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>
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 7cf8a6c..8e52119 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -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;