On Sun, Jan 31, 2021 at 11:50:22PM +0100, Christoph Anton Mitterer wrote: > Hey Hugo. > > > Thanks for your explanation. > I assume such a swapped send/receive would fail at least gracefully?
It'll fail *obviously*. I'm not sure how graceful it is. :) > On Fri, 2021年01月29日 at 19:20 +0000, Hugo Mills wrote: > > In your scenario with MASTER and COPY-1 swapped, you'd have to > > match the received_uuid from the sending side (on old COPY-1) to the > > actual UUID on old MASTER. The code doesn't do this, so you'd have to > > patch send/receive to do this. > > Well from the mailing list thread you've referenced it seems that the > whole thing is rather quite non-trivial... so I guess it's nothing for > someone who has basically no insight into btrfs code ^^ > > It's a pity though, that this doesn't work. Especially the use case of > sending back (backup)snapshots would seem pretty useful. > > Given that this thread is nearly 6 years, I'd guess the whole idea has > been abandoned upstream?! It can be made to work, in a number of different ways -- the option above is one way; another would be to add extra history of subvolume identities -- but I guess it's not a priority for the devs, and at least the latter approach would require extending the on-disk FS format. Both approaches would need changes to the send stream format. Hugo. -- Hugo Mills | Great oxymorons of the world, no. 7: hugo@... carfax.org.uk | The Simple Truth http://carfax.org.uk/ | PGP: E2AB1DE4 |