Btrfs: add helper for em merge logic

This is a prepare work for the following extent map selftest, which
runs tests against em merge logic.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1a462ab85c49..1e05fc7e0e35 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3143,6 +3143,8 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode,
 						    int delay_iput);
 void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work);
 
+int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
+			     struct extent_map **em_in, u64 start, u64 len);
 struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
 		struct page *page, size_t pg_offset, u64 start,
 		u64 len, int create);