btrfs-progs: Add inode item rebuild function.

Add a basic inode item rebuild function for I_ERR_NO_INODE_ITEM.
The main use case is to repair btrfs which fs root has corrupted leaf,
but it is already working for case if the corrupteed fs root leaf/node
contains no inode extent_data.

The repair needs 3 elements for inode rebuild:
1. inode number
   This is quite easy, existing inode_record codes will detect it quite
   well.

2. inode type
   This is the trick part. The only reliable method is to recovery it from
   parent's dir_index/item.
   The remaining method will search for regular file extent for FILE
   type or child's backref for DIR(todo).
   Fallback will be FILE.

Inode name(inode_ref) will be recoverd by nlink repair function.

This is just a fundamental implement, some advanced recovery can be
improved later with btrfs-progs infrastructure change.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/ctree.h b/ctree.h
index eadae76..7861940 100644
--- a/ctree.h
+++ b/ctree.h
@@ -2445,6 +2445,8 @@ static inline int is_fstree(u64 rootid)
 /* inode.c */
 int check_dir_conflict(struct btrfs_root *root, char *name, int namelen,
 		u64 dir, u64 index);
+int btrfs_new_inode(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		u64 ino, u32 mode);
 int btrfs_add_link(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		   u64 ino, u64 parent_ino, char *name, int namelen,
 		   u8 type, u64 *index, int add_backref);