Messages in this thread | | | Date | Thu, 7 May 2015 21:09:58 +0200 | Subject | Re: [PATCH RFC] vfs: add a O_NOMTIME flag | From | Richard Weinberger <> |
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On Thu, May 7, 2015 at 7:20 PM, Zach Brown <zab@redhat.com> wrote: > On Thu, May 07, 2015 at 10:26:17AM +1000, Dave Chinner wrote: >> On Wed, May 06, 2015 at 03:00:12PM -0700, Zach Brown wrote: >> > Add the O_NOMTIME flag which prevents mtime from being updated which can >> > greatly reduce the IO overhead of writes to allocated and initialized >> > regions of files. >> >> Hmmm. How do backup programs now work out if the file has changed >> and hence needs copying again? ie. applications using this will >> break other critical infrastructure in subtle ways. > > By using backup infrastructure that doesn't use cmtime. Like btrfs > send/recv. Or application level backups that know how to do > incrementals from metadata in giant database files, say, without > walking, comparing, and copying the entire thing.
But how can Joey random user know that some of his applications are using O_NOMTIME and his KISS backup program does no longer function as expected?
-- Thanks, //richard
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