On Fri, Oct 12, 2018 at 11:16:16AM +1100, Dave Chinner wrote: > On Wed, Oct 10, 2018 at 09:12:54PM -0700, Darrick J. Wong wrote: > > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > > > A deduplication data corruption is exposed by fstests generic/505 on > > XFS. It is caused by extending the block match range to include the > > partial EOF block, but then allowing unknown data beyond EOF to be > > considered a "match" to data in the destination file because the > > comparison is only made to the end of the source file. This corrupts the > > destination file when the source extent is shared with it. > > > > The VFS remapping prep functions only support whole block dedupe, but > > we still need to appear to support whole file dedupe correctly. Hence > > if the dedupe request includes the last block of the souce file, don't > > include it in the actual dedupe operation. If the rest of the range > > dedupes successfully, then reject the entire request. A subsequent > > patch will enable us to shorten dedupe requests correctly. > > Ok, so this patch rejects whole file dedupe requests, and then a > later patch adds support back in for it? > > Doesn't that leave a bisect landmine behind? Why separate the > functionality like this? Heh, it's a leftover from when I was trying to undo the behavior that bytes_deduped == len even if we rounded down. I gave up on that, so this can match the xfs patch. --D > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx
