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Re: [libvirt] [PATCHv9.5 1/2] blockjob: add qemu capabilities related to block jobs



On 10/27/12 01:00, Eric Blake wrote:
Upstream qemu 1.3 is adding two new monitor commands, 'drive-mirror'
and 'block-job-complete'[1], which can drive live block copy and
storage migration.  [Additionally, RHEL 6.3 had backported an earlier
version of most of the same functionality, but under the names
'__com.redhat_drive-mirror' and '__com.redhat_drive-reopen' and with
slightly different JSON arguments, and has been using patches similar
to these upstream patches for several months now.]

The libvirt API virDomainBlockRebase as already committed for 0.9.12
is flexible enough to expose the basics of block copy, but some
additional features in the 'drive-mirror' qemu command, such as
setting error policy, setting granularity, or using a persistent
bitmap, may later require a new libvirt API virDomainBlockCopy.  I
will wait to add that API until we know more about what qemu 1.3
will finally provide.

This patch caters only to the upstream qemu 1.3 interface, although
I have proven that the changes for RHEL 6.3 can be isolated to
just qemu_monitor_json.c, and the rest of this series will
gracefully handle either interface once the JSON differences are
papered over in a downstream patch.

For consistency with other block job commands, libvirt must handle
the bandwidth argument as MiB/sec from the user, even though qemu
exposes the speed argument as bytes/sec; then again, qemu rounds
up to cluster size internally, so using MiB hides the worst effects
of that rounding if you pass small numbers.

[1]https://lists.gnu.org/archive/html/qemu-devel/2012-10/msg04123.html

* src/qemu/qemu_capabilities.h (QEMU_CAPS_DRIVE_MIRROR)
(QEMU_CAPS_DRIVE_REOPEN): New bits.
* src/qemu/qemu_capabilities.c (qemuCaps): Name them.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONCheckCommands): Set
them.
(qemuMonitorJSONDriveMirror, qemuMonitorDrivePivot): New functions.
* src/qemu/qemu_monitor_json.h (qemuMonitorJSONDriveMirror)
(qemuMonitorDrivePivot): Declare them.
* src/qemu/qemu_monitor.c (qemuMonitorDriveMirror)
(qemuMonitorDrivePivot): New passthroughs.
* src/qemu/qemu_monitor.h (qemuMonitorDriveMirror)
(qemuMonitorDrivePivot): Declare them.
---

v9.5: Update the commit message to point to Kevin's PULL request
(we're one step closer to having drive-mirror in upstream qemu.git,
and a PULL request means the interface is now stable).  Drop
consideration for RHEL 6.3, by dropping the 'bool reopen' parameter;
later patches in the series will trivially rebase that part out.

  src/qemu/qemu_capabilities.c |  4 +++
  src/qemu/qemu_capabilities.h |  1 +
  src/qemu/qemu_monitor.c      | 56 +++++++++++++++++++++++++++++++++++++++--
  src/qemu/qemu_monitor.h      | 12 +++++++++
  src/qemu/qemu_monitor_json.c | 60 ++++++++++++++++++++++++++++++++++++++++++++
  src/qemu/qemu_monitor_json.h | 19 ++++++++++++--
  6 files changed, 148 insertions(+), 4 deletions(-)


ACK.

Peter


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