Re: [PATCH 1/6] xstat: Add a pair of system calls to make extended file stats available

[Ben Hutchings <ben@decadent.org.uk>]

[Apologies for trimming the cc's; I've had to pick this out of an
archive and don't have all the addresses.]

David Howells <dhowells@redhat.com> wrote:
> J. Bruce Fields <bfields@fieldses.org> wrote:
> 
> > > (11) Include granularity fields in the time data to indicate the
> > >      granularity of each of the times (NFSv4 time_delta) [Steve French].
> > 
> > It looks like you're including this with *each* time?  But surely
> > there's no filesystem with different granularity (say) for ctime than
> > for mtime.

There is an extremely obscure filesystem with this property:

VFAT.

> I put it in each time struct to use up the hole there.  I could, I suppose,
> split tv_sec from tv_nsec to get rid of the holes and then put the granularity
> separately.  That means that someone who wanted both the tv_sec and tv_nsec
> would have to fish them out separately, but that's probably okay.
> 
> I could even make the granularity bigger then, to allow for the possibility of
> having a granularity >4s, but I don't know of anywhere that requires a gran >2.
[...]

Try 86,400 seconds - the actual granularity of atime on VFAT.
(For mtime it's 2 seconds, and for ctime 0.01 seconds.)

Ben.

-- 
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
                                                              - Albert Camus