trying to enable the lazy-count feature fails on all my older xfs filesystems: doom ~# xfs_admin -c1 /dev/loop6 Conversion failed, is the filesystem unmounted? cerebro ~# xfs_admin -c1 /dev/sda1 Conversion failed, is the filesystem unmounted? I verified via /proc/mounts that the filesystems are indeed not mounted, and nothing did access the filesystems while the opertation runs. This is a bit unfortunate as it takes many hours to run this command, and then you have no clue what to do about it. It seems this is simply a bug in xfs_repair though.