[libvirt PATCHv2 04/10] conf: qemu: add virtiofs fsdriver type

Ján Tomko jtomko at redhat.com
Fri Jan 24 14:19:42 UTC 2020


On Fri, Jan 24, 2020 at 09:00:04AM +0100, Peter Krempa wrote:
>> @@ -3949,6 +3954,8 @@
>>          while the value <code>immediate</code> means that a host writeback
>>          is immediately triggered for all pages touched during a guest file
>>          write operation <span class="since">(since 0.9.10)</span>.
>> +        <span class="since">Since 6.1.0</span>, <code>type='virtiofs'</code>
>> +        is also supported.
>
>I'd expect some more description on the topic of virtiofs. Not even the
>knowledge-base article is crosslinked from here.
>
>Specifically what does 'mount_tag' mean and perhaps how to use it in the
>guest.
>

The meaning of the target element does not differ from 9pfs which is
already documented below:

        <dt><code>target</code></dt>
        <dd>
          Where the <code>source</code> can be accessed in the guest. For
          most drivers this is an automatic mount point, but for QEMU/KVM
          this is merely an arbitrary string tag that is exported to the
          guest as a hint for where to mount.
        </dd>

But I will add the kbase link here, which shows the usage.

>The validator then forces accessmode to passthrough and that is not
>mentioned here either.
>
>>          </dd>
>>          <dt><code>template</code></dt>
>>          <dd>
>> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
>> index 04854bf816..66757d3b63 100644
>> --- a/docs/schemas/domaincommon.rng
>> +++ b/docs/schemas/domaincommon.rng
>> @@ -2625,6 +2625,22 @@
>>            </optional>
>>            <ref name='virtioOptions'/>
>>          </group>
>> +        <group>
>> +          <attribute name="type">
>> +            <value>virtiofs</value>
>> +          </attribute>
>> +          <optional>
>> +            <attribute name="format">
>> +              <ref name="storageFormat"/>
>> +            </attribute>
>
>The format attribute isn't documented and is rejected by the validator.
>Why bother adding it to the schema?
>

Leftovers from my fight with xmllint. O:-)

>> +          </optional>
>> +          <optional>
>> +            <attribute name="wrpolicy">
>> +              <value>immediate</value>
>> +            </attribute>
>
>This doesn't seem to be documented either.
>
>> +          </optional>
>> +          <ref name='virtioOptions'/>
>> +        </group>
>>          <empty/>
>>        </choice>
>>      </element>
>
>[...]
>
>> diff --git a/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml b/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml
>> new file mode 100644
>> index 0000000000..b02eb5cb2b
>> --- /dev/null
>> +++ b/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml
>> @@ -0,0 +1,38 @@
>> +<domain type='kvm'>
>> +  <name>guest</name>
>> +  <uuid>126f2720-6f8e-45ab-a886-ec9277079a67</uuid>
>> +  <memory unit='KiB'>14680064</memory>
>> +  <currentMemory unit='KiB'>14680064</currentMemory>
>> +  <memoryBacking>
>> +    <source type='file'/>
>> +    <access mode='shared'/>
>> +  </memoryBacking>
>> +  <vcpu placement='static'>2</vcpu>
>> +  <os>
>> +    <type arch='x86_64' machine='pc'>hvm</type>
>> +    <boot dev='hd'/>
>> +  </os>
>> +  <cpu>
>> +    <numa>
>> +      <cell id='0' cpus='0-1' memory='14680064' unit='KiB' memAccess='shared'/>
>> +    </numa>
>
>This is possibly worth mentioning too. Especially if you don't
>cross-link to the knowledge-base in patch 10.
>
>
>The rest looks good. I'm willing to review just the improved
>documentation if you reply with the changes.

Given your exhaustive review of other patches, I'll send v3 separately.

Jano
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