On Fri, 2022-09-09 at 09:48 -0400, Theodore Ts'o wrote: > On Fri, Sep 09, 2022 at 08:47:17AM -0400, Jeff Layton wrote: > > > > i_version only changes now if someone has queried it since it was last > > changed. That makes a huge difference in performance. We can try to > > optimize it further, but it probably wouldn't move the needle much under > > real workloads. > > Good point. And to be clear, from NFS's perspective, you only need to > have i_version bumped if there is a user-visible change to the > file. --- with an explicit exception here of the FIEMAP system call, > since in the case of a delayed allocation, FIEMAP might change from > reporting: > > ext: logical_offset: physical_offset: length: expected: flags: > 0: 0.. 0: 0.. 0: 0: last,unknown_loc,delalloc,eof > > to this: > > ext: logical_offset: physical_offset: length: expected: flags: > 0: 0.. 0: 190087172.. 190087172: 1: last,eof > > after a sync(2) or fsync(2) call, or after time passes. > In general, we want to bump i_version if the ctime changes. I'm guessing that we don't change ctime on a delalloc? If it's not visible to NFS, then NFS won't care about it. We can't project FIEMAP info across the wire at this time, so we'd probably like to avoid seeing an i_version bump in due to delalloc. > > Great! That's what I was hoping for with ext4. Would you be willing to > > pick up these two patches for v6.1? > > > > https://lore.kernel.org/linux-ext4/20220908172448.208585-3-jlayton@xxxxxxxxxx/T/#u > > https://lore.kernel.org/linux-ext4/20220908172448.208585-4-jlayton@xxxxxxxxxx/T/#u > > I think you mean: > > https://lore.kernel.org/linux-ext4/20220908172448.208585-2-jlayton@xxxxxxxxxx/T/#u > https://lore.kernel.org/linux-ext4/20220908172448.208585-3-jlayton@xxxxxxxxxx/T/#u > > Right? > > BTW, sorry for not responding to these patches earlier; between > preparing for the various Linux conferences in Dublin next week, and > being in Zurich and meeting with colleagues at $WORK all of this week, > I'm a bit behind on my patch reviews. > No worries. As long as they're on your radar, that's fine. Thanks! -- Jeff Layton <jlayton@xxxxxxxxxx>
