Messages in this thread | | | From | Nikanth Karthikesan <> | Subject | Re: [PATCH] loop: Update mtime when writing using aops | Date | Fri, 9 Apr 2010 10:52:32 +0530 |
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On Friday 09 April 2010 01:08:38 Jens Axboe wrote: > On Thu, Apr 08 2010, Tvrtko Ursulin wrote: > > On Thursday 08 April 2010 13:45:39 Jens Axboe wrote: > > > On Thu, Apr 08 2010, Nikanth Karthikesan wrote: > > > > Update mtime when writing to backing filesystem using the address > > > > space operations write_begin and write_end. > > > > > > You forgot to include a 'why' :-) > > > > > > Not that I disagree with the patch, just curious what made you make the > > > change. > >
Sorry, for the bad terse changelog.
> > You mean how the bug was found? I originally reported this problem > > against openSUSE 11.2 kernel, where when you have a dm-crypt loop > > filesystem the container file modification time does not get updated with > > use. Consequence of that is that backup runs would miss the fact > > container has changed. > > > > Maybe one could argue it is a security feature in this scenario :), but > > as the problem turns out to be unrelated to the crypto case, rather > > contained in the loop driver itself, it looks like that would not hold. > > > :-) > > I suppose you could update the mtime on tear down, since then it would > also be safe to actually backup. But same difference in the end I > suppose, I'll add the patch. >
If we update mtime only during tear down, we might miss to backup after a system crash or scenarios where the loop device is not deleted after use during backup. Also when relatime is used, it is better to change mtime on time. :-)
Thanks for taking the patch.
Thanks Nikanth
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