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)
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index 1383afd..3df0185 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h
@@ -467,6 +467,8 @@ btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs, gfp_t gfp_flags); struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs); struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask); +struct bio *btrfs_bio_clone_partial(struct bio *orig, gfp_t gfp_mask, + int offset, int size); struct btrfs_fs_info; struct btrfs_inode;