On Mon, 2024-07-01 at 09:53 -0400, Josef Bacik wrote: > On Mon, Jul 01, 2024 at 06:26:36AM -0400, Jeff Layton wrote: > > This set is essentially unchanged from the last one, aside from the > > new file in Documentation/. I had a review comment from Andi Kleen > > suggesting that the ctime_floor should be per time_namespace, but I > > think that's incorrect as the realtime clock is not namespaced. > > > > At LSF/MM this year, we had a discussion about the inode change > > attribute. At the time I mentioned that I thought I could salvage the > > multigrain timestamp work that had to be reverted last year [1]. That > > version had to be reverted because it was possible for a file to get a > > coarse grained timestamp that appeared to be earlier than another file > > that had recently gotten a fine-grained stamp. > > > > This version corrects the problem by establishing a per-time_namespace > > ctime_floor value that should prevent this from occurring. In the above > > situation that was problematic before, the two files might end up with > > the same timestamp value, but they won't appear to have been modified in > > the wrong order. > > > > That problem was discovered by the test-stat-time gnulib test. Note that > > that test still fails on multigrain timestamps, but that's because its > > method of determining the minimum delay that will show a timestamp > > change will no longer work with multigrain timestamps. I have a patch to > > change the testcase to use a different method that I've posted to the > > bug-gnulib mailing list. > > > > The big question with this set is whether the performance will be > > suitable. The testing I've done seems to show performance parity with > > multigrain timestamps enabled, but it's hard to rule this out regressing > > some workload. > > > > This set is based on top of Christian's vfs.misc branch (which has the > > earlier change to track inode timestamps as discrete integers). If there > > are no major objections, I'd like to let this soak in linux-next for a > > bit to see if any problems shake out. > > > > [1]: https://lore.kernel.org/linux-fsdevel/20230807-mgctime-v7-0-d1dec143a704@xxxxxxxxxx/ > > > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > I have a few nits that need to be addressed, but you can add > > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > > to the series once they're addressed. Thanks, > Thanks! Fixed them up in my tree. I left the IS_I_VERSION check out as well, and added a note to the changelog on the btrfs patch. -- Jeff Layton <jlayton@xxxxxxxxxx>
