On Tue, Jan 12, 2021 at 12:08 PM Graham Cobb <g.bt...@cobb.uk.net> wrote: > > On 12/01/2021 11:27, Filipe Manana wrote: > > ... > > In other words, what I think we should have is a check that forbids > > using two roots for an incremental send that are not snapshots of the > > same subvolume (have different parent uuids). > > Are you suggesting that rule should also apply for clone sources (-c > option)? Or are clone sources handled differently from the parent in the > code?
No, I'm not. The clone sources are different, and are used only to find extents for cloning and not for computing differences between snapshots. The exception is when -p is not passed to 'btrfs send' and one or more roots are passed to it with -c, in which case btrfs-progs determines the "best parent" - so it would check as well if the chosen parent is a snapshot of the same subvolume. My suggestion was making this on the kernel side, just in case there are other users of the ioctl other than btrfs-progs. -- Filipe David Manana, “Whether you think you can, or you think you can't — you're right.”
