Just a note, anaconda is now using "attr2" for installs from FC6 and beyond, so
space is more efficiently shared between extents & attributes in the inode.
With that, selinux & attrs should still be pretty efficient in 256 bytes,
without the extra space overhead of the larger inodes, and the 512-byte default
patch has been removed. Note that attr2 is still not the default in mkfs.xfs,
though - it can be set at mkfs or mount time.