xfs: resolve fork names in trace output

Emit whichfork values as text strings in the ftrace output.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

fs/xfs/libxfs/xfs_types.h

@@ -87,6 +87,11 @@ typedef void *		xfs_failaddr_t;
 #define	XFS_ATTR_FORK	1
 #define	XFS_COW_FORK	2
 
+#define XFS_WHICHFORK_STRINGS \
+	{ XFS_DATA_FORK, 	"data" }, \
+	{ XFS_ATTR_FORK,	"attr" }, \
+	{ XFS_COW_FORK,		"cow" }
+
 /*
  * Min numbers of data/attr fork btree root pointers.
  */