On Thu, Nov 13, 2014 at 6:54 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Thu, Nov 13, 2014 at 08:02:43AM -0500, Trond Myklebust wrote: >> On Wed, Nov 12, 2014 at 7:28 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote: >> > On Wed, Nov 12, 2014 at 09:26:16AM -0500, Trond Myklebust wrote: >> >> On Wed, Nov 12, 2014 at 5:24 AM, Christoph Hellwig <hch@xxxxxx> wrote: >> >> > On Wed, Nov 12, 2014 at 09:27:10AM +1100, Dave Chinner wrote: >> >> >> To clarify what Christoph wrote, XFS updates i_version is updated >> >> >> once per transaction that modifies the inode. So if a VFS level >> >> >> operation results in multiple transactions then each transaction >> >> >> will but the version. >> >> >> >> >> >> It was implemented that way because nobody could tell me what the >> >> >> actual granularity requirement for change detection was. Hence what >> >> >> I implemented was "be able to detect any persistent change that is >> >> >> made" to cover all bases. > > FWIW, ext4 takes the same approach. See Ted's post today: > > http://www.spinics.net/lists/linux-ext4/msg46194.html > > "The inode_inc_iversion() in mark4_ext4_iloc_dirty() is probably not > necessary, since we already should be incrementing i_version whenever > ctime and mtime gets updated. The inode_inc_iversion() there is more > of a "belt and suspenders" safety thing, on the theory that the extra > bump in i_version won't hurt anything." > It will hurt if it causes all the NFS clients to blow their caches unnecessarily. Who asked for this? -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
