block: Add bio_clone_fast()

bio_clone() just got more expensive - however, most users of bio_clone()
don't actually need to modify the biovec. If they aren't modifying the
biovec, and they can guarantee that the original bio isn't freed before
the clone (also true in most cases), we can just point the clone at the
original bio's biovec.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 1a31f9d9e057..1f83f4a3083e 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -328,6 +328,8 @@ extern mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries);
 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 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 void __bio_clone(struct bio *, struct bio *);
 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);