QEMU requires us to pass the topmost node(-name) in the backing chain as the 'device' argument for the blockdev-mirror/block-commit commands. Otherwise QEMU complains: "Need a root block node" Since libvirt always puts the copy-on-read driver on top of the backing chain, blockjobs on disks which use "copy_on_read" fail. The series below fixes that by passing the proper node. This fixes it just fine for the mirror, but for block-commit we still get another error due to a bug in qemu: "'libvirt-4-format' is not in this backing file chain" Additionally one weird thing happens with block-stream (blockpull). If I pass the layer below the copy-on-read as 'device', everything works. This is kind of weird as the documentation for that is the same. If I pass the nodename of copy-on-read. Max, Kevin, could you please comment on the block-stream part and possibly also on the plans to fix the issue with block-commit? Cc: Max Reitz <mreitz@xxxxxxxxxx> CC: Kevin Wolf <kwolf@xxxxxxxxxx> https://bugzilla.redhat.com/show_bug.cgi?id=1792195 Peter Krempa (4): qemu: blockcopy: Actually unplug unused images when mirror job fails to start qemu: domain: Extract code to determine topmost nodename to qemuDomainDiskGetTopNodename qemu: Fix value of 'device' argument for blockdev-mirror qemu: Fix value of 'device' argument for block-commit src/qemu/qemu_domain.c | 38 ++++++++++++++++++++++++++------------ src/qemu/qemu_domain.h | 4 ++++ src/qemu/qemu_driver.c | 6 +++--- src/qemu/qemu_migration.c | 2 +- 4 files changed, 34 insertions(+), 16 deletions(-) -- 2.24.1
