On Fri, Sep 11, 2015 at 09:25:25AM +0800, Qu Wenruo wrote: > Josef Bacik wrote on 2015/09/10 16:27 -0400: > >When dropping a snapshot we need to account for the qgroup changes. If we drop > >the snapshot in all one go then the backref code will fail to find blocks from > >the snapshot we dropped since it won't be able to find the root in the fs root > >cache. This can lead to us failing to find refs from other roots that pointed > >at blocks in the now deleted root. To handle this we need to not remove the fs > >roots from the cache until after we process the qgroup operations. Do this by > >adding dropped roots to a list on the transaction, and letting the transaction > >remove the roots at the same time it drops the commit roots. This will keep all > >of the backref searching code in sync properly, and fixes a problem Mark was > >seeing with snapshot delete and qgroups. Thanks,Btrfs: keep dropped roots in > >cache until transaciton commit > > Mark will definitely be happy with this patch, as quite a good basis > for snapshot deletion. Indeed. My tests against a kernel with Josefs patches and my snapshot deletion code seem to be passing. I'll have something on the list shortly. Thanks, --Mark -- Mark Fasheh -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
