Re: blockdev operations [was: [Qemu-devel] KVM call agenda for Tuesday 28th]

[Paolo Bonzini <pbonzini@redhat.com>]

Il 28/02/2012 17:07, Eric Blake ha scritto:
> { 'enum': 'BlockdevOp',
>   'data': [ 'snapshot', 'snapshot-mirror', 'reopen' ] }
> { 'type': 'BlockdevAction',
>   'data': {'device': 'str', 'op': 'BlockdevOp',
>            'file': 'str', '*format': 'str', '*reuse': 'bool',
>            '*mirror': 'str', '*mirror-format': 'str' } }
> { 'command': 'blkdev-group-action-sync',
>   'data': { 'actionlist': [ 'BlockdevAction' ] } }
> 
> 
> The overall command is atomic - either all operations will succeed, or
> the command returns an error pointing to the name of the device that
> failed leaving all devices in their pre-command state.  Then, for each
> requested operation:
> 
> If op is 'snapshot', then 'file' names the new snapshot file; 'reuse' is
> optional (defaults to false) to say whether qemu creates the file from
> scratch, or opens an existing file with the backing file already
> populated correctly.  'format' gives the format of 'file', defaulting to
> qcow2.  'mirror' and 'mirror-format' must not be given.
> 
> If op is 'snapshot-mirror', then 'mirror' is mandatory; and both 'file'
> and 'mirror' are opened as a new mirrored snapshot.  Again, 'reuse'
> affects whether qemu creates the new files from scratch or trusts oVirt
> to pre-create both files with backing file information; and 'format' and
> 'mirror-format' allow control over the image format being opened.

Could snapshot-mirror be done as two separate commands for snapshot (or
reopen) and mirror?  This removes the need for mirror and mirror-format.

> If op is 'reopen', then 'file' is the name of the file to be opened to
> replace the current file tied to the blockdev, with type given by
> 'format'.  'reuse', 'mirror', and 'mirror-format' must not be given.

Otherwise looks good.

Paolo