Re: [libvirt] [PATCH 2/2] rbd: Implement buildVolFrom using RBD cloning

On 21-01-16 21:55, John Ferlan wrote: > > > On 12/23/2015 04:29 AM, Wido den Hollander wrote: >> RBD supports cloning by creating a snapshot, protecting it and create >> a child image based on that snapshot afterwards. >> >> The RBD storage driver will try to find a snapshot with zero deltas between >> the current state of the original volume and the snapshot. >> >> If such a snapshot is found a clone/child image will be created using >> the rbd_clone2() function from librbd. >> >> It will use the same features, strip size and stripe count as the parent image. >> >> This implementation will only create a single snapshot on the parent image if >> this never changes. That should improve performance when removing the parent >> image at some point. >> >> During build the decision will be made to user rbd_diff_iterate() or rbd_diff_iterate2(). >> The latter is faster, but only available on Ceph versions after 0.94 (Hammer). >> >> Cloning is only supported if RBD format 2 is used. All images created by libvirt >> are already format 2. >> >> If a RBD format 1 image is used as the original volume libvirt will return VIR_ERR_OPERATION_UNSUPPORTED > > Long line... and the API should return 0 or -1 (based on other > backends)... Caller doesn't expect that VIR_ERR* on return... > > I assume you realize that 'virsh vol-create-from' and 'vol-clone' end up > using the same API... > > FWIW: I reviewed bottom up - I may also have been distracted more than > once looking for specific code. Hopefully this is coherent ;-) > Thanks for all the feedback, really appreciate it! Working on a revised version of all the patches right now. Rebasing a lot, editing commits, etc, etc. The coding style changes are new to me though. I run make syntax-check and that works. Never knew that this was needed: static int virStorageRBDXXXXXXX All the exisiting code does: static int virStorageRBDXXXXXX

Anyway, I'll get back with new patches. Ignore anything which is on the list right now. Btw, a Pull Request mechanism like Github would be so much easier than sending patches per e-mail ;)