I've just learned about this mount option, nodiratime, and while I can find some documentation on atime and noatime, I can't find much about nodiratime.

The mount(8) man page lists noatime but not nodiratime, and yet I found it in the 2.6.17.13 source code for inode.c and namespace.c.

Is this a current/ supported option? Do filesystems (ext2/3, reiserfs, jfs, xfs) have explicit support for it, or is it a kernel function (updating the access times on files and directories). Does noatime imply nodiratime? (directories are files, etc.)

All I found with Google is people posting their fstab, showing they use nodiratime, and one usenet posting from 1998 thanking the developers for putting it in and I'd like a few more details, is it recommended? to be avoided? Avoided for / but recommended other partitions?

Thanks.