xfs: read and write metadata inode directory tree

Plumb in the bits we need to load metadata inodes from a named entry in
a metadir directory, create (or hardlink) inodes into a metadir
directory, create metadir directories, and flag inodes as being metadata
files.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_trace.c

@@ -46,6 +46,8 @@
 #include "xfs_parent.h"
 #include "xfs_rmap.h"
 #include "xfs_refcount.h"
+#include "xfs_metafile.h"
+#include "xfs_metadir.h"
 
 /*
  * We include this last to have the helpers above available for the trace