Btrfs: new helper btrfs_bio_clone_partial
This adds a new helper btrfs_bio_clone_partial, it'll allocate a cloned
bio that only owns a part of the original bio's data.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 292e458..db2bbf9 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2720,6 +2720,24 @@ struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
return bio;
}
+struct bio *btrfs_bio_clone_partial(struct bio *orig, gfp_t gfp_mask,
+ int offset, int size)
+{
+ struct bio *bio;
+ struct btrfs_io_bio *btrfs_bio;
+
+ /* this will never fail when it's backed by a bioset */
+ bio = bio_clone_fast(orig, gfp_mask, btrfs_bioset);
+ ASSERT(bio);
+
+ btrfs_bio = btrfs_io_bio(bio);
+ btrfs_bio->csum = NULL;
+ btrfs_bio->csum_allocated = NULL;
+ btrfs_bio->end_io = NULL;
+
+ bio_trim(bio, offset >> 9, size >> 9);
+ return bio;
+}
static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
unsigned long bio_flags)