Re: [PATCH 17/17] xfs: support for synchronous DAX faults

+#define XFS_MAP_SUPPORTED (LEGACY_MAP_MASK | MAP_SYNC)

I'd kill this define.  Also is there any good reason that we have
to add LEGACY_MAP_MASK instead of assuming it's supported in the
core?

 #endif
 	.mmap		= xfs_file_mmap,
+	.mmap_supported_flags	= XFS_MAP_SUPPORTED,
 	.open		= xfs_file_open,
 	.release	= xfs_file_release,
 	.fsync		= xfs_file_fsync,

I usually either reformat all members to be aligned again, or if that's
too much churn (in this case it probably is) just use a single space
before the = to minimize the alignment differences.

Otherwise your changes look good to me.