On Thu, Apr 25, 2013 at 09:32:37PM -0400, Josef Bacik wrote: > On Thu, Apr 25, 2013 at 07:08:29PM -0600, Dave Chinner wrote: > > On Thu, Apr 25, 2013 at 08:24:04PM -0400, Josef Bacik wrote: > > > On Thu, Apr 25, 2013 at 04:45:56PM -0600, Dave Chinner wrote: > > > > On Thu, Apr 25, 2013 at 10:12:56AM -0400, Josef Bacik wrote: > > ..... > > > > > + $here/src/fsync-tester -s $SEED -r -t $test_num $extra $testfile > > > > > + if [ $? -ne 0 ]; then > > > > > + _unmount_flakey > > > > > + _cleanup > > > > > + exit > > > > > + fi > > > > > + > > > > > + _md5_checksum $testfile > > > > > + _drop_writes > > > > > + _unmount_flakey > > > > > > > > So, _drop_writes suspends the dm-flakey device, freezes the > > > > filesystem, turns off writes then thaws the filesystem, right? > > > > > > > > If so, doesn't that mean you're not actually testing fsync() as the > > > > freeze will effectively sync the entire filesystem before you start > > > > dropping writes? > > > > > > > > I can see why you want to stop unmount from writing back metadata to > > > > simulate a crash, but if you've already frozen the filesystem then > > > > writeback has already occurred before you stop the writes. So I > > > > can't see how this is actually testing fsync - what it appears to be > > > > testing is the fileystem freeze code... > > > > > > > > [ This is precisely the issue that XFS shutdown ioctls deal with to > > > > trigger an immediate forced shutdown of the filesystem that prevents > > > > *any* further writes from being issued by the filesystem - no sync > > > > operations get in the way and change the state of the filesystem > > > > after then fsync call, so we know that what is on disk is what was > > > > written by the sync/fsync calls being tested. > > > > > > > > This is how we test sync/fsync in other XFS tests (e.g. > > > > xfs/137-140), and this is the reason why us XFS people have > > > > suggested that other filesystems should implement the ioctls for > > > > this functionality rather than try to invent new ways of trying > > > > to stop filesystems from writing back dirty metadata for fsync/sync > > > > testing.... > > > > > > > > Besides, if a corruption is detected, you need a method of stopping > > > > all dirty metadata from being written back in the filesystem to > > > > prevent propagation of the corruption. These ioctls should just be > > > > an interface into that mechanism. ] > > > > > > > > > > So I need to look at what this does. I don't think it freezes the file system, > > > > `dmsetup suspend` ends up in dm_suspend(). This calls lock_fs(), which > > calls freeze_bdev().... > > > > If you do `dmsetup suspend --nolockfs` then it won't freeze the > > filesystem during the suspend... > > > > Ok so I think I'll just make this test do all the iterations of the fsync tester > with and without --nolockfs, since without --nolockfs I'm still seeing problems, > does that sound reasonable? Sounds like a fine plan to me ;) Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
