Re: [Qemu-devel] [PATCH v2 RESEND 1/4] qmp: Add command 'blockdev-backup'

[Eric Blake <eblake@redhat.com>]

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On 11/03/2014 02:47 AM, Fam Zheng wrote:
> Similar to drive-backup, but this command uses a device id as target
> instead of creating/opening an image file.
> 
> Also add blocker on target bs, since the target is also a named device
> now.
> 
> Add check and report error for bs == target which became possible but is
> an illegal case with introduction of blockdev-backup.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/backup.c       | 28 +++++++++++++++++++++++++++
>  blockdev.c           | 47 ++++++++++++++++++++++++++++++++++++++++++++++
>  qapi/block-core.json | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  qmp-commands.hx      | 44 +++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 172 insertions(+)
> 

> +++ b/qapi/block-core.json
> @@ -674,6 +674,40 @@
>              '*on-target-error': 'BlockdevOnError' } }
>  
>  ##
> +# @BlockdevBackup
> +#
> +# @device: the name of the device which should be copied.
> +#
> +# @target: the name of the backup target device.
> +#
> +# @sync: what parts of the disk image should be copied to the destination
> +#        (all the disk, only the sectors allocated in the topmost image, or
> +#        only new I/O).
> +#
> +# @speed: #optional the maximum speed, in bytes per second.

Maybe mention 'the default is 0, for unlimited'?

> +#
> +# @on-source-error: #optional the action to take on an error on the source,
> +#                   default 'report'.  'stop' and 'enospc' can only be used
> +#                   if the block device supports io-status (see BlockInfo).
> +#
> +# @on-target-error: #optional the action to take on an error on the target,
> +#                   default 'report' (no limitations, since this applies to
> +#                   a different block device than @device).
> +#
> +# Note that @on-source-error and @on-target-error only affect background I/O.
> +# If an error occurs during a guest write request, the device's rerror/werror
> +# actions will be used.
> +#
> +# Since: 2.2

Is 2.2 still the target since this missed soft freeze, or has it slipped
to 2.3?  Particularly since...

> +##
> +{ 'type': 'BlockdevBackup',
> +  'data': { 'device': 'str', 'target': 'str',
> +            'sync': 'MirrorSyncMode',
> +            '*speed': 'int',
> +            '*on-source-error': 'BlockdevOnError',
> +            '*on-target-error': 'BlockdevOnError' } }
> +
> +##
>  # @blockdev-snapshot-sync
>  #
>  # Generates a synchronous snapshot of a block device.
> @@ -793,6 +827,25 @@
>  { 'command': 'drive-backup', 'data': 'DriveBackup' }
>  
>  ##
> +# @blockdev-backup
> +#
> +# Start a point-in-time copy of a block device to a new destination.  The
> +# status of ongoing blockdev-backup operations can be checked with
> +# query-block-jobs where the BlockJobInfo.type field has the value 'backup'.

This reuses the same job type as 'drive-backup'; but that seems okay to me.

> +# The operation can be stopped before it has completed using the
> +# block-job-cancel command.
> +#
> +# For the arguments, see the documentation of BlockdevBackup.
> +#
> +# Returns: Nothing on success.
> +#          If @device or @target is not a valid block device, DeviceNotFound.
> +#
> +# Since 2.3

...you mixed in 2.3 here.


> +SQMP
> +blockdev-backup
> +------------
> +
> +The device version of drive-backup: this command takes a existing named device

s/a existing/an existing/

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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