f2fs: enable in-place-update for fdatasync

This patch enforces in-place-updates only when fdatasync is requested.
If we adopt this in-place-updates for the fdatasync, we can skip to write the
recovery information.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ab36025..8f8685e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -998,6 +998,7 @@
 	FI_INLINE_DATA,		/* used for inline data*/
 	FI_APPEND_WRITE,	/* inode has appended data */
 	FI_UPDATE_WRITE,	/* inode has in-place-update data */
+	FI_NEED_IPU,		/* used fo ipu for fdatasync */
 };
 
 static inline void set_inode_flag(struct f2fs_inode_info *fi, int flag)