Hello, > > Alongside this, there's also a requirement for being able to do > round-trip send/receive while preserving the ability to do incremental > sends. This is likely to be related to the above bug-fix. I did a > complete write-up of what's happening, and what needs to happen, here: > > http://www.spinics.net/lists/linux-btrfs/msg44089.html
I missed that discussion, but I proposed a different solution in a similar thread about send/receive (https://www.spinics.net/lists/linux-btrfs/msg60694.html) I think it's not very useful that received_uuid encodes where the subvolume comes from. All that send / receive should care about, is that the contents of source(s) used for incremental send match the contents of subvolumes on the receive side. Let's call it, for example, "contents_uuid". The rules would be simple: operations that preserve contents preserve contents_uuid ; operations that change contents change contents_uuid. For simplicity and performance reasons, in order to not need tracking of changes, we could allow for some false positives, where contents_uuid changed when data did not. A simpler to implement set of rules could look like this: - rw subvolumes have no contents_uuid - changing rw subvolume to ro assigns a random contents_uuid - ro snapshot of rw subvolume gets a random contents_uuid - ro snapshot of ro subvolume preserves contents_uuid - send/receive preserves contents_uuid (after successful receive) And then the rule for send / receive would be: - send transmits contents_uuid of subvolumes used as clone sources, which are matched to subvolumes having identical contents_uuid on the receive side. Does it make sense? Did I miss something? I haven't received any feedback last time, which is why I bring it up again for discussion. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
