Re: [Qemu-block] [Qemu-devel] [PATCH v4 2/6] replication: add shared-disk and shared-disk-id options

[Hailiang Zhang]

On 2017/4/12 22:28, Eric Blake wrote:
> On 04/12/2017 09:05 AM, zhanghailiang wrote:
> > We use these two options to identify which disk is
> > shared
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > Signed-off-by: Wen Congyang <address@hidden>
> > Signed-off-by: Zhang Chen <address@hidden>
> > ---
> > v4:
> > - Add proper comment for primary_disk (Stefan)
> > v2:
> > - Move g_free(s->shared_disk_id) to the common fail process place (Stefan)
> > - Fix comments for these two options
> > ---
> > +++ b/qapi/block-core.json
> > @@ -2661,12 +2661,20 @@
> >   #          node who owns the replication node chain. Must not be given in
> >   #          primary mode.
> >   #
> > +# @shared-disk-id: Id of shared disk while is replication mode, if @shared-disk
> > +#                  is true, this option is required (Since: 2.10)
> > +#
> > +# @shared-disk: To indicate whether or not a disk is shared by primary VM
> > +#               and secondary VM. (The default is false) (Since: 2.10)
> > +#
> >   # Since: 2.9
> >   ##
> >   { 'struct': 'BlockdevOptionsReplication',
> >     'base': 'BlockdevOptionsGenericFormat',
> >     'data': { 'mode': 'ReplicationMode',
> > -            '*top-id': 'str' } }
> > +            '*top-id': 'str',
> > +            '*shared-disk-id': 'str',
> > +            '*shared-disk': 'bool' } }
> Do we need a separate bool and string? Or is it sufficient to say that
> if shared-disk is omitted, we are not sharing, and that if a shared-disk
> string is present, then we are sharing and it names the id of the shared
> disk.

Er,  Yes, We need both of them, the command line of secondary sides is like:

 -drive if=virtio,id=active-disk0,driver=replication,mode=secondary,\
        file.driver=qcow2,top-id=active-disk0,\
        file.file.filename=/mnt/ramfs/active_disk.img,\
        file.backing=hidden_disk0,shared-disk=on
We only need the bool shared-disk to indicate whether disk is sharing or not, 
but
for primary side, we need to the blockdev-add command to tell primary which 
disk is shared.
  { 'execute': 'blockdev-add',
    'arguments': {
        'driver': 'replication',
        'node-name': 'rep',
        'mode': 'primary',
        'shared-disk-id': 'primary_disk0',
        'shared-disk': true,
        'file': {
            'driver': 'nbd',
            'export': 'hidden_disk0',
            'server': {
                'type': 'inet',
                'data': {
                    'host': 'xxx.xxx.xxx.xxx',
                    'port': 'yyy'
                }
            }
        }
     }
  }