f2fs: align f2fs maximum name length to linux based filesystem

The maximum filename length supported in linux is 255 characters.
So let's follow that.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index a1f3844..2851ae6 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -189,6 +189,9 @@
 	unsigned int max_depth;
 	unsigned int level;
 
+	if (namelen > F2FS_NAME_LEN)
+		return NULL;
+
 	if (npages == 0)
 		return NULL;