f2fs: add F2FS_INLINE_DOTS to recover missing dot dentries

If f2fs was corrupted with missing dot dentries, it needs to recover them after
fsck.f2fs detection.

The underlying precedure is:

1. The fsck.f2fs remains F2FS_INLINE_DOTS flag in directory inode, if it detects
missing dot dentries.

2. When f2fs looks up the corrupted directory, it triggers f2fs_add_link with
proper inode numbers and their dot and dotdot names.

3. Once f2fs recovers the directory without errors, it removes F2FS_INLINE_DOTS
finally.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index 502f28c..591f8c3 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -178,6 +178,7 @@
 #define F2FS_INLINE_DATA	0x02	/* file inline data flag */
 #define F2FS_INLINE_DENTRY	0x04	/* file inline dentry flag */
 #define F2FS_DATA_EXIST		0x08	/* file inline data exist flag */
+#define F2FS_INLINE_DOTS	0x10	/* file having implicit dot dentries */
 
 #define MAX_INLINE_DATA		(sizeof(__le32) * (DEF_ADDRS_PER_INODE - \
 						F2FS_INLINE_XATTR_ADDRS - 1))