Re: [Libguestfs] [PATCH 2/2] nbd: Add new qemu:joint-allocation metadata context

On Sat, Jun 12, 2021 at 02:39:44AM +0300, Nir Soffer wrote: > Since this change is not simple, and the chance that we also get the dirty > bitmap included in the result seems to be very low, I decided to check the > direction of merging multiple extents. > > I started with merging "base:allocation" and "qemu:dirty-bitmap:xxx" since > we already have both. It was not hard to do, although it is not completely > tested yet. > > Here is the merging code: > https://gerrit.ovirt.org/c/ovirt-imageio/+/115216/1/daemon/ovirt_imageio/... > > To make merging easy and safe, we map the NBD_STATE_DIRTY bit to a private bit > so it cannot clash with the NBD_STATE_HOLE bit: > https://gerrit.ovirt.org/c/ovirt-imageio/+/115215/1/daemon/ovirt_imageio/... > > Here is a functional test using qemu-nbd showing that it works: > https://gerrit.ovirt.org/c/ovirt-imageio/+/115216/1/daemon/test/client_te... > > I'll try to use "qemu:allocation-depth" in a similar way next week, probably > mapping depth > 0 to EXTENT_EXISTS, to use when reporting holes in > single qcow2 images. > > If this is successful, we can start using this in the next ovirt release, and we > don't need "qemu:joint-allocation". That's nice to know. So at this point, we'll drop the patch on qemu:joint-allocation, and instead focus on teh patch that improves qemu-img map output to make it easier to use in the same way that qemu:allocation-depth is.