On Tue, Sep 18, 2018 at 06:28:37PM +0000, Gervais, Francois wrote: > > No. It is already possible (by setting received UUID); it should not be > made too open to easy abuse. > > > Do you mean edit the UUID in the byte stream before btrfs receive?
No, there's an ioctl to change the received UUID of a subvolume. It's used by receive, at the very end of the receive operation. Messing around in this area is basically a recipe for ending up with a half-completed send/receive full of broken data because the receiving subvolume isn't quite as identical as you thought. It enforces the rules for a reason. Now, it's possible to modify the send stream and the logic around it a bit to support a number of additional modes of operation (bidirectional send, for example), but that's queued up waiting for (a) a definitive list of send stream format changes, and (b) David's bandwidth to put them together in one patch set. If you want to see more on the underlying UUID model, and how it could be (ab)used and modified, there's a write-up here, in a thread on pretty much exactly the same proposal that you've just made: https://www.spinics.net/lists/linux-btrfs/msg44089.html Hugo. -- Hugo Mills | Great films about cricket: Monster's No-Ball hugo@... carfax.org.uk | http://carfax.org.uk/ | PGP: E2AB1DE4 |
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