ping? On Thu, Jan 23, 2014 at 09:23:50PM +1100, Dave Chinner wrote: > Hi folks, > > In making xfs_repair handle discontiguous directory blocks properly, > it uncovered the fact that xfs_metadump has never handled > discontiguous directory blocks properly. It doesn't handle > discontiguous block format directories, and there are a couple of > other cases where it is just says "too hard" and gives up, leading > to un-obfuscated, corrupt or missing directory blocks in the > metadump image. xfs/291 on CRC enabled filesystems was causing all > three of these conditions to occur. > > This patchset fixes metadump to fully support all forms of > discontiguous directory blocks. It changes the obfuscation code from > reading and extent at a time and trying to slice and dice the > objects within it - which will never work for objects that need CRC > recalculation as a result of obfuscation - to dealing with > individual objects. This does affect IO patterns somewhat - single > large contiguous IOs turn into multiple smaller sequential IOs - but > it means that we can use the object verifiers to do CRC > recalculation correctly. > > It also means we can walk the extent tree to gather discontiguous > extents into a single buffer to build an object fom multiple IOs. > This is what all the other directory block IO does, and we need to > do it here too. > > The result is that the code is simpler and more obvious in what it > does - the "walk over a large extent" code is generic rather than > object specific, and the discontiguous block code is separated from > the single block object code. Hence both cases are clearer and > easier to understand. > > And it works, unlike the old code. > > FWIW, with this fixed and xfs/291 passing, the only remaining > outstanding work that is blocking a 3.2.0 release is to trap IO > verifier errors in repair so we repair/rebuild objects based on CRC > errors. > > Comments, flames, thoughts all welcome. > > Cheers, > > Dave. > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs > -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
