[RFC] [patch 3/3] i_version update for ext4: user interface

[Peter Staubach]

J. Bruce Fields wrote:
> On Tue, Jan 23, 2007 at 11:52:08AM -0700, Andreas Dilger wrote:
>   
>> On Jan 23, 2007  18:24 +0100, Cordenner jean noel wrote:
>>     
>>> This patch adds a  ``st_i_version'' field in the stat
>>> structure, and modifies the stat(2) syscall accordingly. Currently the
>>> change is only visible on i386 and x86_64 archs.
>>>       
>> What is the need for exporting i_version to userspace?
>>     
>
> Maybe none, but it seems potentially really useful to me; in practice
> aren't most uses of mtime/ctime exactly in order to find out if the file
> has changed recently?
>
> Who else is asking for finer time resolutions?  Is it because they need
> the precision (or the inter-file comparison) or because they need to
> know whether a file has changed?
>
> Isn't anybody that currently maintains some cached information about a
> filesystem currently living with the same races as NFS?

Doesn't the BSD stat struct have a field like this?  If so, perhaps
they can remember why it was deemed to be interesting?

    Thanx...

       ps