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authorMing Lei <tom.leiming@gmail.com>2017-02-14 23:28:59 +0800
committerShaohua Li <shli@fb.com>2017-02-15 11:22:05 -0800
commitc18a1e09008de7d8bd82b046d38a88f4285d53f9 (patch)
treeb6db3c3286d3086c587a76da819c9272dc91b19d /block
parent26483819f89c5cf9d27620d70c95afeeeb9bece5 (diff)
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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>
Diffstat (limited to 'block')
-rw-r--r--block/bio.c61
1 files changed, 48 insertions, 13 deletions
diff --git a/block/bio.c b/block/bio.c
index 2b375020fc49..9e2b33ddca0a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -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;
}
@@ -699,9 +699,44 @@ 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
* @bio: destination bio