xfs: replace xfs_mode_to_ftype table with switch statement

commit 1fc4d33fed124fb182e8e6c214e973a29389ae83.

The size of the xfs_mode_to_ftype[] conversion table
was too small to handle an invalid value of mode=S_IFMT.

Instead of fixing the table size, replace the conversion table
with a conversion helper that uses a switch statement.

Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index 6a3fe31..0051a34 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -35,10 +35,9 @@
 extern struct xfs_name	xfs_name_dotdot;
 
 /*
- * directory filetype conversion tables.
+ * Convert inode mode to directory entry filetype
  */
-#define S_SHIFT 12
-extern const unsigned char xfs_mode_to_ftype[];
+extern const unsigned char xfs_mode_to_ftype(int mode);
 
 /*
  * directory operations vector for encode/decode routines