Re: [Qemu-devel] [PATCH] block: allow write-threshold on device name

[Eric Blake <eblake@redhat.com>]

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On 06/07/2015 02:53 AM, Amos Kong wrote:
> On Sun, Jun 7, 2015 at 9:38 AM, Eric Blake <eblake@redhat.com> wrote:
>>
>> Commit e2462113 allowed the ability to fire an event if a BDS
>> node exceeds a threshold during a write, but limited the option
>> to only work on node names.  For convenience, expand this to
>> allow a device name as a way to set the threshold on the BDS
>> at the active layer of the device.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>  block/write-threshold.c | 5 ++---
>>  1 file changed, 2 insertions(+), 3 deletions(-)
>>

>> -    bs = bdrv_find_node(node_name);
>> +    bs = bdrv_lookup_bs(node_name, node_name, errp);
> 
> It means we can pass device name by 'node_name' parameter？

Yes. The two namespaces cannot overlap, so it is unambiguous that a
device name means the active node attached to the device (we use it in a
number of other commands).

> do we need to update command doc in qapi/block-core.json?

Good call; existing docs state:

# @block-set-write-threshold
...
# @node-name: graph node name on which the threshold must be set.
...
{ 'command': 'block-set-write-threshold',
  'data': { 'node-name': 'str', 'write-threshold': 'uint64' } }

so I'll prepare a v2 that tweaks it.

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


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