Re: [Qemu-devel] [PATCH 1/4] qmp: add block_stream command

[Adam Litke <agl@US.IBM.COM>]

Under libvirt, I get the following error when trying to start a block
stream:

qerror: bad call in function 'do_block_stream':
qerror: -> error format '{ 'class': 'NotSupported', 'data': {} }' not found
qerror: call at blockdev.c:808
2011-08-23 11:30:09.974: shutting down

Is this patch missing a part of the qerror definition?

On Tue, 2011-08-23 at 13:58 +0100, Stefan Hajnoczi wrote:
> This patch introduces the block_stream HMP/QMP command.  It is currently
> unimplemented and returns the 'NotSupported' error.
> 
> block_stream
> ------------
> 
> Copy data from a backing file into a block device.
> 
> The block streaming operation is performed in the background until the
> entire backing file has been copied.  This command returns immediately
> once streaming has started.  The status of ongoing block streaming
> operations can be checked with query-block-jobs.  The operation can be
> stopped before it has completed using the block_job_cancel command.
> 
> If a base file is specified then sectors are not copied from that base
> file and its backing chain.  When streaming completes the image file
> will have the base file as its backing file.  This can be used to stream
> a subset of the backing file chain instead of flattening the entire
> image.
> 
> On successful completion the image file is updated to drop the backing
> file.
> 
> Arguments:
> 
> - device: device name (json-string)
> - base:   common backing file (json-string, optional)
> 
> Errors:
> 
> DeviceInUse:    streaming is already active on this device
> DeviceNotFound: device name is invalid
> NotSupported:   image streaming is not supported by this device
> 
> Events:
> 
> On completion the BLOCK_JOB_COMPLETED event is raised with the following
> fields:
> 
> - type:     job type ("stream" for image streaming, json-string)
> - device:   device name (json-string)
> - end:      maximum progress value (json-int)
> - position: current progress value (json-int)
> - speed:    rate limit, bytes per second (json-int)
> - error:    error message (json-string, only on error)
> 
> The completion event is raised both on success and on failure.  On
> success position is equal to end.  On failure position and end can be
> used to indicate at which point the operation failed.
> 
> On failure the error field contains a human-readable error message.
> There are no semantics other than that streaming has failed and clients
> should not try to interpret the error string.
> 
> Examples:
> 
> -> { "execute": "block_stream", "arguments": { "device": "virtio0" } }
> <- { "return":  {} }
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> ---
>  blockdev.c      |   18 +++++++++++++++
>  blockdev.h      |    1 +
>  hmp-commands.hx |   14 +++++++++++
>  monitor.c       |    3 ++
>  monitor.h       |    1 +
>  qerror.h        |    3 ++
>  qmp-commands.hx |   65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  7 files changed, 105 insertions(+), 0 deletions(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index d272659..208bfc9 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -790,3 +790,21 @@ int do_block_resize(Monitor *mon, const QDict *qdict, QObject **ret_data)
> 
>      return 0;
>  }
> +
> +int do_block_stream(Monitor *mon, const QDict *params, QObject **ret_data)
> +{
> +    const char *device = qdict_get_str(params, "device");
> +    BlockDriverState *bs;
> +
> +    bs = bdrv_find(device);
> +    if (!bs) {
> +        qerror_report(QERR_DEVICE_NOT_FOUND, device);
> +        return -1;
> +    }
> +
> +    /* This command is not yet implemented.  The device not found check above
> +     * is done so that error ordering will not change when fully implemented.
> +     */
> +    qerror_report(QERR_NOT_SUPPORTED);
> +    return -1;
> +}
> diff --git a/blockdev.h b/blockdev.h
> index 3587786..ad98d37 100644
> --- a/blockdev.h
> +++ b/blockdev.h
> @@ -65,5 +65,6 @@ int do_change_block(Monitor *mon, const char *device,
>  int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
>  int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data);
>  int do_block_resize(Monitor *mon, const QDict *qdict, QObject **ret_data);
> +int do_block_stream(Monitor *mon, const QDict *qdict, QObject **ret_data);
> 
>  #endif
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 0ccfb28..2a16fd9 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -70,6 +70,20 @@ but should be used with extreme caution.  Note that this command only
>  resizes image files, it can not resize block devices like LVM volumes.
>  ETEXI
> 
> +    {
> +        .name       = "block_stream",
> +        .args_type  = "device:B,base:s?",
> +        .params     = "device [base]",
> +        .help       = "copy data from a backing file into a block device",
> +        .user_print = monitor_user_noop,
> +        .mhandler.cmd_new = do_block_stream,
> +    },
> +
> +STEXI
> +@item block_stream
> +@findex block_stream
> +Copy data from a backing file into a block device.
> +ETEXI
> 
>      {
>          .name       = "eject",
> diff --git a/monitor.c b/monitor.c
> index ada51d0..dc55fca 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -468,6 +468,9 @@ void monitor_protocol_event(MonitorEvent event, QObject *data)
>          case QEVENT_SPICE_DISCONNECTED:
>              event_name = "SPICE_DISCONNECTED";
>              break;
> +        case QEVENT_BLOCK_JOB_COMPLETED:
> +            event_name = "BLOCK_JOB_COMPLETED";
> +            break;
>          default:
>              abort();
>              break;
> diff --git a/monitor.h b/monitor.h
> index 4f2d328..135c927 100644
> --- a/monitor.h
> +++ b/monitor.h
> @@ -35,6 +35,7 @@ typedef enum MonitorEvent {
>      QEVENT_SPICE_CONNECTED,
>      QEVENT_SPICE_INITIALIZED,
>      QEVENT_SPICE_DISCONNECTED,
> +    QEVENT_BLOCK_JOB_COMPLETED,
>      QEVENT_MAX,
>  } MonitorEvent;
> 
> diff --git a/qerror.h b/qerror.h
> index 8058456..eba9238 100644
> --- a/qerror.h
> +++ b/qerror.h
> @@ -139,6 +139,9 @@ QError *qobject_to_qerror(const QObject *obj);
>  #define QERR_NO_BUS_FOR_DEVICE \
>      "{ 'class': 'NoBusForDevice', 'data': { 'device': %s, 'bus': %s } }"
> 
> +#define QERR_NOT_SUPPORTED \
> +    "{ 'class': 'NotSupported', 'data': {} }"
> +
>  #define QERR_OPEN_FILE_FAILED \
>      "{ 'class': 'OpenFileFailed', 'data': { 'filename': %s } }"
> 
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 03f67da..60c9bdf 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -694,6 +694,71 @@ Example:
>  EQMP
> 
>      {
> +        .name       = "block_stream",
> +        .args_type  = "device:B,base:s?",
> +        .params     = "device [base]",
> +        .user_print = monitor_user_noop,
> +        .mhandler.cmd_new = do_block_stream,
> +    },
> +
> +SQMP
> +block_stream
> +------------
> +
> +Copy data from a backing file into a block device.
> +
> +The block streaming operation is performed in the background until the entire
> +backing file has been copied.  This command returns immediately once streaming
> +has started.  The status of ongoing block streaming operations can be checked
> +with query-block-jobs.  The operation can be stopped before it has completed
> +using the block_job_cancel command.
> +
> +If a base file is specified then sectors are not copied from that base file and
> +its backing chain.  When streaming completes the image file will have the base
> +file as its backing file.  This can be used to stream a subset of the backing
> +file chain instead of flattening the entire image.
> +
> +On successful completion the image file is updated to drop the backing file.
> +
> +Arguments:
> +
> +- device: device name (json-string)
> +- base:   common backing file (json-string, optional)
> +
> +Errors:
> +
> +DeviceInUse:    streaming is already active on this device
> +DeviceNotFound: device name is invalid
> +NotSupported:   image streaming is not supported by this device
> +
> +Events:
> +
> +On completion the BLOCK_JOB_COMPLETED event is raised with the following
> +fields:
> +
> +- type:     job type ("stream" for image streaming, json-string)
> +- device:   device name (json-string)
> +- end:      maximum progress value (json-int)
> +- position: current progress value (json-int)
> +- speed:    rate limit, bytes per second (json-int)
> +- error:    error message (json-string, only on error)
> +
> +The completion event is raised both on success and on failure.  On
> +success position is equal to end.  On failure position and end can be
> +used to indicate at which point the operation failed.
> +
> +On failure the error field contains a human-readable error message.  There are
> +no semantics other than that streaming has failed and clients should not try
> +to interpret the error string.
> +
> +Examples:
> +
> +-> { "execute": "block_stream", "arguments": { "device": "virtio0" } }
> +<- { "return":  {} }
> +
> +EQMP
> +
> +    {
>          .name       = "blockdev-snapshot-sync",
>          .args_type  = "device:B,snapshot-file:s?,format:s?",
>          .params     = "device [new-image-file] [format]",

-- 
Thanks,
Adam