Kernel check

    # cd /boot
    # grep _ACL config-`uname -r` | grep XFS
    CONFIG_XFS_POSIX_ACL=y

So - kernel seems to have it.

Check for get/setfacl:

    # aptitude search acl | grep " acl "
    i   acl                             - Access control list utilities

Good - acl installed (as is libacl1).

Have a mount point I'm not using right now:

    # grep transfer /etc/fstab
    /dev/vg0/transfer  /transfer  xfs  defaults 0 0

So - it's an lvm logical volume in the vg0 volume group.

Check it's current mount

    # mount | grep transfer
    /dev/mapper/vg0-transfer on /transfer type xfs (rw)

Unmount it:

    # umount /transfer

then change fstab:

    /dev/vg0/transfer  /transfer  xfs  acl,defaults 0 0

Try to mount it

    # mount /transfer

Fails:

    mount: wrong fs type, bad option, bad superblock on /dev/mapper/vg0-transfer,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

dmesg:

    [15075807.670164] XFS: unknown mount option [acl].


Am suspecting that since the kernel is built with the config for XFS ACL that this could be LVM related.

But it's too late to go digging right now. Hints welcome.