Re: [libvirt] [PATCH v3 10/18] blockcopy: allow block device destination

To date, anyone performing a block copy and pivot ends up with the destination being treated as <disk type='file'>. While this works for data access for a block device, it has at least one noticeable shortcoming: virDomainGetBlockInfo() reports allocation differently for block devices visited as files (the size of the device) than for block devices visited as <disk type='block'> (the maximum sector used, as reported by qemu); and this difference is significant when trying to manage qcow2 format on block devices that can be grown as needed. Of course, the more powerful virDomainBlockCopy() API can already express the ability to set the <disk> type. But a new API can't be backported, while a new flag to an existing API can; and it is also rather inconvenient to have to resort to the full power of generating XML when just adding a flag to the older call will do the trick. So this patch enhances blockcopy to let the user flag when the resulting XML after the copy must list the device as type='block'. * include/libvirt/libvirt.h.in (VIR_DOMAIN_BLOCK_REBASE_COPY_DEV): New flag. * src/libvirt.c (virDomainBlockRebase): Document it. * tools/virsh-domain.c (opts_block_copy, blockJobImpl): Add --blockdev option. * tools/virsh.pod (blockcopy): Document it. * src/qemu/qemu_driver.c (qemuDomainBlockRebase): Allow new flag. (qemuDomainBlockCopy): Remember the flag, and make sure it is only used on actual block devices. * tests/qemuxml2argvdata/qemuxml2argv-disk-mirror.xml: Test it. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- include/libvirt/libvirt.h.in | 2 ++ src/libvirt.c | 8 +++-- src/qemu/qemu_driver.c | 36 ++++++++++++++-------- .../qemuxml2argvdata/qemuxml2argv-disk-mirror.xml | 4 +-- tools/virsh-domain.c | 6 ++++ tools/virsh.pod | 7 +++-- 6 files changed, 45 insertions(+), 18 deletions(-)