[PATCH V5 15/33] block: introduce bio_clone_seg_bioset()

Ming Lei
2018-05-24T09:01:20Z

There is one use case(DM) which requires to clone bio segment by
segement, so introduce this API.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/bio.c | 56 +++++++++++++++++++++++++++++++++++++++--------------
include/linux/bio.h | 1 +
2 files changed, 43 insertions(+), 14 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index d0debb22ee34..63d4fe85f42e 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -644,21 +644,13 @@ 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, bool page)
{
struct bvec_iter iter;
struct bio_vec bv;
struct bio *bio;
+ int nr_vecs = page ? bio_pages(bio_src) : bio_segments(bio_src);

/*
* Pre immutable biovecs, __bio_clone() used to just do a memcpy from
@@ -682,7 +674,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
* __bio_clone_fast() anyways.
*/

- bio = bio_alloc_bioset(gfp_mask, bio_pages(bio_src), bs);
+ bio = bio_alloc_bioset(gfp_mask, nr_vecs, bs);
if (!bio)
return NULL;
bio->bi_disk = bio_src->bi_disk;
@@ -700,8 +692,13 @@ 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_page(bv, bio_src, iter)
- bio->bi_io_vec[bio->bi_vcnt++] = bv;
+ if (page) {
+ bio_for_each_page(bv, bio_src, iter)
+ bio->bi_io_vec[bio->bi_vcnt++] = bv;
+ } else {
+ bio_for_each_segment(bv, bio_src, iter)
+ bio->bi_io_vec[bio->bi_vcnt++] = bv;
+ }
break;
}

@@ -719,9 +716,40 @@ 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, true);
+}
EXPORT_SYMBOL(bio_clone_bioset);

/**
+ * bio_clone_seg_bioset - clone a bio segment by segment
+ * @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_seg_bioset(struct bio *bio_src, gfp_t gfp_mask,
+ struct bio_set *bs)
+{
+ return __bio_clone_bioset(bio_src, gfp_mask, bs, false);
+}
+EXPORT_SYMBOL(bio_clone_seg_bioset);
+
+/**
* bio_add_pc_page - attempt to add page to bio
* @q: the target queue
* @bio: destination bio
diff --git a/include/linux/bio.h b/include/linux/bio.h
index b24c00f99c9c..61a04c131641 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -475,6 +475,7 @@ 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_seg_bioset(struct bio *, gfp_t, struct bio_set *bs);

extern struct bio_set fs_bio_set;

--
2.9.5