On Tue, Sep 29 2009 at 5:39pm -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > Hi > > I uploaded a new version there. It has selective re-read and it has > optimized locking --- it does no remote communication if the chunk already > exists, so it should be as efficient as Jon's approach. > > Jon, please look at it and review the patches, if you find out that this > approach can't work at all, we can drop it and go with your approach. If > it is OK, we can consider adopting it, it looks simpler than making > clustered-exception-store. > > Mikulas > > > On Mon, 28 Sep 2009, Mikulas Patocka wrote: > > > Hi > > > > I uploaded my test clustered snapshots to > > http://people.redhat.com/mpatocka/patches/kernel/clustered-snapshots-preview/ I have updated the following quilt tree and folded Mikulas' clustered snapshots patches into the end: http://people.redhat.com/msnitzer/patches/snapshot-merge/kernel/2.6.31/ Changes include: . check for {prepare,commit}_merge not {prepare,commit}_exception in snapshot_merge_process (dm-snapshot-merge-process.patch) . removed kernel/dm-exception-store-return-zero-when-empty.patch - adjusted dm-exception-store-merge-accounting.patch to preserve established kernel<->userspace interface - adjusted a few other patches . removed kernel/dm-snapshot-dont-insert-before-existing-chunk.patch . moved proper cleanup of memory exceptions in merge_callback() from dm-snapshot-merge-use-larger-io-when-merging.patch to dm-snapshot-merge-interlock-writes.patch - this merge_callback() code walks exceptions in reverse but has not been tested on a larger merge to know whether the 'back-merge' of exceptions is properly being accounted for when cleaning up the in-core snapshot exceptions. - I think the fact that the exception cleanup is 2 stage (first disk, then all in memory exceptions in reverse) may make back-merge "just work"... . added agk's pending patches to the front of the series - this works on 2.6.31 - I haven't rebased to 2.6.32-rc1 yet I have done some light snapshot-merge testing to verify that this updated snapshot-merge quilt tree builds and works as expected. I'll be testing more extensively shortly (particularly back-merge). I have also updated the LVM2 snapshot-merge patches to work on 2.02.54-cvs: http://people.redhat.com/msnitzer/patches/snapshot-merge/lvm2/LVM2-2.02.54/ One thing to note is dm-snapshot now depends on dm_cluster_locking; when I tried to insmod dm-snapshot.ko I got: dm_snapshot: Unknown symbol dm_cluster_lock_exit dm_snapshot: Unknown symbol dm_cluster_lock_by_str dm_snapshot: Unknown symbol dm_cluster_lock_init I'm also seeing: DLM (built Sep 11 2009 23:48:05) installed dlm: no local IP address has been set dlm: cannot start dlm lowcomms -107 device-mapper: dm-cluster-locking: Failed to create lockspace: dm-snap Am I just missing the relevant LVM2 bits to push down proper args to the snapshot_ctr()? Seems to me that we could do better about defaulting to _not_ triggering DLM/clustered calls... Also, I have no idea if I somehow messed up the clustered-locking patches when I refreshed them to work with my quilt tree. I had a quick review of the patch changes I made and the only one that needs a closer look was dm-snapshot-clustered-locking-optimize.patch. Mikulas please review/rebase your tree using my updated quilt tree and let me know if you see any issues. Maybe you have newer patches at this point? Thanks, Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
