[libvirt] [PATCH 0/9] qemu: Add quorum support to libvirt

[Matthias Gatto]

On Wed, Dec 17, 2014 at 10:53 AM, Matthias Gatto
<matthias.gatto at outscale.com> wrote:
> On Mon, Dec 8, 2014 at 7:31 PM, Matthias Gatto
> <matthias.gatto at outscale.com> wrote:
>> The purpose of these patches is to introduce quorum for libvirt
>> I've try to follow this proposal:
>> http://www.redhat.com/archives/libvir-list/2014-May/msg00533.html
>>
>> This feature ask for 6 task:
>>
>> 1) Allow a _virStorageSource
>> to contain more than one backing store.
>>
>> Therefore we have to treat the field virStorageSourcePtr backingStores
>> as an array instead of a pointer.
>> But doing that, most of the backingStore field would be an array contening
>> only one element.
>> So I've decide to allocate the array only if there is more than 1
>> backing store in a _virStorageSource.
>> Because all the actual libvirt code use the backingStore field
>> as a pointer and we needs want to change that, I've decide to encapsulate
>> the backingStore field to simplifie the array manipulation.
>>
>> 2) Add the missing field a quorum need in _virStorageSource and
>> the VIR_STORAGE_TYPE_QUORUM and VIR_STORAGE_FILE_QUORUM in
>> their respectives enums.
>>
>> 3) Parse and format the xml
>> Because a quorum allows to have more than one backing store at the same level
>> we need to change virDomainDiskDefFormat and virDomainDiskDefParseXML
>> to call virDomainDiskBackingStoreFormat and virDomainDiskBackingStoreParse
>> in a loop.
>> virDomainDiskBackingStoreFormat and virDomainDiskBackingStoreParse can
>> call themself recursively in a loop because a quorum can contain another
>> quorum
>>
>> 4) Add nodename
>> We need to add nodename support in _virStorageSource because qemu
>> use them for their child.
>>
>> 5) Build qemu string
>> As for the xml, we have to call the function which create quorum recursively.
>> But this task have the problem explained here:
>> http://www.redhat.com/archives/libvir-list/2014-October/msg00529.html
>> The _virStorageSource missing some informations that can be passed to
>> a child, and therefore this version of quorum is incomplet.
>>
>> 6) Allow to hotplug/change a disk in a quorum
>> This part is not present in these patches because for this task
>> we have to use blockdev-add, and currently libvirt use
>> device_add for hotpluging that doesn't allow to hotplug quorum childs.
>>
>> There is 3 way to handle this problem:
>>       1) create a virDomainBlockDevAdd function in libvirt witch call
>>       blockdev-add.
>>
>>       2) use blockdev-add instead of device_add in qemuMonitorJSONAddDevice
>>
>>       3) write a hack which uses blockdev-add when only attaching quorum
>>       (but i'm pretty sure this solution is not the good one)
>>
>> Matthias Gatto (9):
>>   virstoragefile: Add virStorageSourceGetBackingStore
>>   virstoragefile: Always use virStorageSourceGetBackingStore to get
>>     backing store
>>   virstoragefile: Add virStorageSourceSetBackingStore
>>   virstoragefile: Always use virStorageSourceSetBackingStore to set
>>     backing store
>>   virstoragefile: Treat backingStore as a pointer or an array
>>   virstoragefile: Add quorum in virstoragefile
>>   domain_conf: Read and Write quorum config
>>   qemu: Add quorum support in qemuBuildDriveDevStr
>>   virstoragefile: Add node-name
>>
>>  src/conf/domain_conf.c                | 193 ++++++++++++++++++++++++++--------
>>  src/conf/storage_conf.c               |   7 +-
>>  src/libvirt_private.syms              |   3 +
>>  src/qemu/qemu_cgroup.c                |   4 +-
>>  src/qemu/qemu_command.c               | 114 ++++++++++++++++++++
>>  src/qemu/qemu_domain.c                |   3 +-
>>  src/qemu/qemu_driver.c                |  20 ++--
>>  src/security/security_dac.c           |   2 +-
>>  src/security/security_selinux.c       |   4 +-
>>  src/security/virt-aa-helper.c         |   2 +-
>>  src/storage/storage_backend.c         |  12 +--
>>  src/storage/storage_backend_fs.c      |  12 +--
>>  src/storage/storage_backend_logical.c |   4 +-
>>  src/storage/storage_driver.c          |   2 +-
>>  src/util/virstoragefile.c             | 136 +++++++++++++++++++++---
>>  src/util/virstoragefile.h             |  12 +++
>>  tests/virstoragetest.c                |  18 ++--
>>  17 files changed, 445 insertions(+), 103 deletions(-)
>>
>> --
>> 1.8.3.1
>>
>
> ping
ping