Can not use hmp block_resize command with -blockdev option

Can not use hmp block_resize command with -blockdev option

[zhao xiaojun]

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Hi,
I use -blockdev option to specify a drive when qemu boot and i want to
resize it with hmp block_resize command. The hmp block_resize comand's
arguments: block_resize device new_size.
So I query the device by qmp query_block command, but the device filed of
the result output is NULL string.

result output:
{
  "return": [
    {
      "io-status": "ok",
      "device": "",
        ...
}

I noticed that the qmp block_resize command supports device or node-name as
argument.

If i can continue use the the hmp block_resize command with the device
argument?

Regards.

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Re: Can not use hmp block_resize command with -blockdev option

[John Snow]

On 3/16/21 11:43 PM, zhao xiaojun wrote:
> Hi,
> I use -blockdev option to specify a drive when qemu boot and i want to 
> resize it with hmp block_resize command. The hmp block_resize comand's 
> arguments: block_resize device new_size.
> So I query the device by qmp query_block command, but the device filed 
> of the result output is NULL string.
> 
> result output:
> {
>    "return": [
>      {
>        "io-status": "ok",
>        "device": "",
>          ...
> }
> 
> I noticed that the qmp block_resize command supports device or node-name 
> as argument.
> 
> If i can continue use the the hmp block_resize command with the device 
> argument?
> 
> Regards.

I'm not sure what you're asking: hmp's block_resize doesn't accept 
node-name arguments as you've found. Are you not able to use QMP's 
block_resize?

--js

Re: Can not use hmp block_resize command with -blockdev option

[Kevin Wolf]

Am 17.03.2021 um 23:49 hat John Snow geschrieben:
> On 3/16/21 11:43 PM, zhao xiaojun wrote:
> > Hi,
> > I use -blockdev option to specify a drive when qemu boot and i want to
> > resize it with hmp block_resize command. The hmp block_resize comand's
> > arguments: block_resize device new_size.
> > So I query the device by qmp query_block command, but the device filed
> > of the result output is NULL string.
> > 
> > result output:
> > {
> >    "return": [
> >      {
> >        "io-status": "ok",
> >        "device": "",
> >          ...
> > }
> > 
> > I noticed that the qmp block_resize command supports device or node-name
> > as argument.
> > 
> > If i can continue use the the hmp block_resize command with the device
> > argument?
> > 
> > Regards.
> 
> I'm not sure what you're asking: hmp's block_resize doesn't accept node-name
> arguments as you've found. Are you not able to use QMP's block_resize?

We should probably fix HMP block_resize to accept node names.

Kevin

Re: Can not use hmp block_resize command with -blockdev option

[zhao xiaojun]

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Thanks you, that's really good idea. And I also have the following question:

There are some hmp and qmp commands in my scripts, they need the device as
an argument. Recently. i used the -blockdev replace the -drive to
specify the disk drive, then use  qmp's query_block to query the device,
but the device is NULL string. For the hmp's block_resize, I can use qmp's
block_resize do. But the other commands(qpm's block-job-cancel etc.), they
only support the device argument. So I can only continue to use -drive to
specify disk drive.

I was trying to see the source(qemu v5.1.0):
qmp_query_device()
  -> bdrv_query_info()
      info->device = g_strdup(blk_name(blk))
the device is set to blk_name(blk), and the blk->name is set in
the monitor_add_blk()

the -blockdev:
qmp_blockdev_add()
   -> bds_tree_init()
     -> bdrv_open()
   ...
the qmp_blockdev_add() doesn't call the monitor_add_blk().

Questions:
Why can not qmp_blockdev_add() call the monitor_add_blk()?
Will the hmp and qmp commands that only support device as an argument be
compat with the -blockdev option?

Kevin Wolf <kwolf@redhat.com> 于2021年3月18日周四 下午6:50写道：

> Am 17.03.2021 um 23:49 hat John Snow geschrieben:
> > On 3/16/21 11:43 PM, zhao xiaojun wrote:
> > > Hi,
> > > I use -blockdev option to specify a drive when qemu boot and i want to
> > > resize it with hmp block_resize command. The hmp block_resize comand's
> > > arguments: block_resize device new_size.
> > > So I query the device by qmp query_block command, but the device filed
> > > of the result output is NULL string.
> > >
> > > result output:
> > > {
> > >    "return": [
> > >      {
> > >        "io-status": "ok",
> > >        "device": "",
> > >          ...
> > > }
> > >
> > > I noticed that the qmp block_resize command supports device or
> node-name
> > > as argument.
> > >
> > > If i can continue use the the hmp block_resize command with the device
> > > argument?
> > >
> > > Regards.
> >
> > I'm not sure what you're asking: hmp's block_resize doesn't accept
> node-name
> > arguments as you've found. Are you not able to use QMP's block_resize?
>
> We should probably fix HMP block_resize to accept node names.
>
> Kevin
>
>

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Re: Can not use hmp block_resize command with -blockdev option

[Kevin Wolf]

Am 18.03.2021 um 16:15 hat zhao xiaojun geschrieben:
> Thanks you, that's really good idea. And I also have the following question:
> 
> There are some hmp and qmp commands in my scripts, they need the device as
> an argument. Recently. i used the -blockdev replace the -drive to
> specify the disk drive, then use  qmp's query_block to query the device,
> but the device is NULL string. For the hmp's block_resize, I can use qmp's
> block_resize do. But the other commands(qpm's block-job-cancel etc.), they
> only support the device argument. So I can only continue to use -drive to
> specify disk drive.
> 
> I was trying to see the source(qemu v5.1.0):
> qmp_query_device()
>   -> bdrv_query_info()
>       info->device = g_strdup(blk_name(blk))
> the device is set to blk_name(blk), and the blk->name is set in
> the monitor_add_blk()
> 
> the -blockdev:
> qmp_blockdev_add()
>    -> bds_tree_init()
>      -> bdrv_open()
>    ...
> the qmp_blockdev_add() doesn't call the monitor_add_blk().
> 
> Questions:
> Why can not qmp_blockdev_add() call the monitor_add_blk()?
> Will the hmp and qmp commands that only support device as an argument be
> compat with the -blockdev option?

QMP doesn't have such commands. For commands that operate on the
frontend (the guest device), they accept the id of the -device. For
commands that relate to the backend, you can specify node-name.

It's only HMP that may not support these alternatives in some places. We
can just extend it.

Kevin

Re: Can not use hmp block_resize command with -blockdev option

[LKML]

On Thu, 18 Mar 2021 17:17:50 +0100
Kevin Wolf <kwolf@redhat.com> wrote:

> Am 18.03.2021 um 16:15 hat zhao xiaojun geschrieben:
> > Thanks you, that's really good idea. And I also have the following
> > question:
> > 
> > There are some hmp and qmp commands in my scripts, they need the
> > device as an argument. Recently. i used the -blockdev replace the
> > -drive to specify the disk drive, then use  qmp's query_block to
> > query the device, but the device is NULL string. For the hmp's
> > block_resize, I can use qmp's block_resize do. But the other
> > commands(qpm's block-job-cancel etc.), they only support the device
> > argument. So I can only continue to use -drive to specify disk
> > drive.
> > 
> > I was trying to see the source(qemu v5.1.0):
> > qmp_query_device()  
> >   -> bdrv_query_info()  
> >       info->device = g_strdup(blk_name(blk))
> > the device is set to blk_name(blk), and the blk->name is set in
> > the monitor_add_blk()
> > 
> > the -blockdev:
> > qmp_blockdev_add()  
> >    -> bds_tree_init()
> >      -> bdrv_open()  
> >    ...
> > the qmp_blockdev_add() doesn't call the monitor_add_blk().
> > 
> > Questions:
> > Why can not qmp_blockdev_add() call the monitor_add_blk()?
> > Will the hmp and qmp commands that only support device as an
> > argument be compat with the -blockdev option?  
> 
> QMP doesn't have such commands. For commands that operate on the
> frontend (the guest device), they accept the id of the -device. For
> commands that relate to the backend, you can specify node-name.
> 
> It's only HMP that may not support these alternatives in some places.
> We can just extend it.
> 
> Kevin
> 

Ok, thank you very much.

Regards.