[Qemu-devel] [PATCH v3 0/8] Mirrored block writes

[Paolo Bonzini <pbonzini@redhat.com>]

v3 comes with a new QMP command drive-mirror, an improved
blockdev-snapshot-sync that just reuses transaction functionality, and
a new image creation mode enum.  I also tested that the command can be
used to migrate without shared storage.

Tested with the following scenarios:

a) mirror only

1) create base.qcow2 and starat QEMU with it

2) Execute the following QMP command

{ "execute": "qmp_capabilities" }
{ "execute": "transaction", "arguments":
  {'actions': [
    { 'type': 'drive-mirror', 'data' :
      { 'device': 'ide0-hd0', 'target': '/home/pbonzini/mirror.qcow2' } } ] } }
{ "execute": "cont" }

3) hibernate the guest (this requires an IDE disk and -cpu kvm64,-kvmclock)

4) restart the guest with mirror.qcow2


b) Same as (a) with drive-mirror command.


c) streaming to new image

1) start QEMU with an existing image test.img

2) execute the following HMP commands

drive_mirror -s ide0-hd0 /home/pbonzini/mirror.qed qed
block_stream ide0-hd0

3) shut down the guest (sorry, this took a looong time and I forgot to
hibernate here)

4) move away the base image

5) restart the guest with mirror.qed


d) atomic snapshot+mirror (QMP only):

1) start QEMU with an existing image test.img

2) Execute the following QMP command

{ "execute": "qmp_capabilities" }
{ "execute": "transaction", "arguments":
  {'actions': [
    { 'type': 'blockdev-snapshot-sync', 'data' :
      { 'device': 'ide0-hd0', 'snapshot-file': '/home/pbonzini/base.qcow2' } },
    { 'type': 'drive-mirror', 'data' :
      { 'device': 'ide0-hd0', 'target': '/home/pbonzini/mirror.qcow2' } } ] } }
{ "execute": "cont" }

3) hibernate the guest (this requires an IDE disk and -cpu kvm64,-kvmclock)

4) check that mirror.qcow2 has test.img as the base

5) restart the guest with base.qcow2

6) restart the guest with mirror.qcow2


v2->v3:
        replace reuse argument with NewImageMode enum and mode argument;
        renamed all commands and actions; implemented blockdev-snapshot-sync
        in terms of group snasphots; added new drive-mirror command and
        HMP equivalent.

Marcelo Tosatti (1):
  Add blkmirror block driver

Paolo Bonzini (7):
  fix format name for backing file
  qapi: complete implementation of unions
  rename blockdev-group-snapshot-sync
  add mode field to blockdev-snapshot-sync transaction item
  qmp: convert blockdev-snapshot-sync to a wrapper around transactions
  add mirroring to transaction
  add drive-mirror command and HMP equivalent

 Makefile.objs             |    2 +-
 block/blkmirror.c         |  239 +++++++++++++++++++++++++++++++++++++++++++++
 blockdev.c                |  232 ++++++++++++++++++++++++-------------------
 hmp-commands.hx           |   31 +++++-
 hmp.c                     |   34 ++++++-
 hmp.h                     |    1 +
 qapi-schema-test.json     |   10 ++
 qapi-schema.json          |  119 ++++++++++++++++++----
 qmp-commands.hx           |  105 +++++++++++++++-----
 scripts/qapi-types.py     |    5 +
 scripts/qapi-visit.py     |   31 ++++++-
 test-qmp-input-visitor.c  |   18 ++++
 test-qmp-output-visitor.c |   34 +++++++
 13 files changed, 707 insertions(+), 154 deletions(-)
 create mode 100644 block/blkmirror.c

-- 
1.7.7.6