Jan Engelhardt [off-list ref] wrote:

quoted

quoted

(8) Allow the filesystem to indicate what it can/cannot provide: A
    filesystem can now say it doesn't support a standard stat feature if
    that isn't available.

What for?

Given xstat.otime=0, how would you determine whether the file is really 
tagged with a date of 1970, or whether it's just the fs which didnot 
store this kind of information.

I was thinking more of stuff that's already in the Linux stat struct, some of
which is fabricated because the underlying fs doesn't support it.

Take RomFS for example: it fabricates all of st_mtime, st_atime, st_ctime,
st_nlinks, st_blocks, st_uid and st_gid because none of them are stored in the
medium

Similarly, UbiFS fabricates st_blocks and complains in a comment that it makes
no sense for that type of filesystem.

There are other examples.

David