On Thu, May 7, 2015 at 7:20 PM, Zach Brown <zab@xxxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
