btrfs-progs: file: Introduce function to read out file content

Introduce a new function, btrfs_read_file(), to read out data of a file
inode.

This function will iterate through EXTENT_DATA items and handle
inline/prealloc/hole file extents.

Compression is not supported yet.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/ctree.h b/ctree.h
index 1d0622d9..f89ffeb7 100644
--- a/ctree.h
+++ b/ctree.h
@@ -2776,4 +2776,7 @@ int btrfs_get_extent(struct btrfs_trans_handle *trans,
 int btrfs_punch_hole(struct btrfs_trans_handle *trans,
 		     struct btrfs_root *root,
 		     u64 ino, u64 offset, u64 len);
+int btrfs_read_file(struct btrfs_root *root, u64 ino, u64 start, u64 len,
+		    char *dest);
+
 #endif