[libvirt] [PATCH 2/8] Support leases in guest XML and lock manager

[Eric Blake]

On 05/11/2011 03:33 AM, Daniel P. Berrange wrote:
> A lock manager may operate in various modes. The direct mode of
> operation is to obtain locks based on the resources associated
> with devices in the XML. The indirect mode is where the app
> creating the domain provides explicit leases for each resource
> that needs to be locked. This XML extension allows for listing
> resources in the XML
> 
>   <devices>
>      ...
>      <lease>
>        <lockspace>somearea</lockspace>
>        <key>thequickbrownfoxjumpsoverthelazydog</key>
>        <target path='/some/lease/path' offset='23432'/>
>      </lease>
>      ...
>   </devices>
> 
> The 'lockspace' is a unique identifier for the lockspace which
> the lease is associated
> 
> The 'key' is a unique identifier for the resource associated
> with the lease.
> 
> The 'target' is the file on disk where the leases are held.

Sounds reasonable on the XML front.  However,

> 
> * docs/schemas/domain.rng: Add lease schema
> * src/conf/domain_conf.c, src/conf/domain_conf.h: parsing and
>   formatting for leases
> * tests/qemuxml2argvdata/qemuxml2argv-lease.args,
>   tests/qemuxml2argvdata/qemuxml2argv-lease.xml,
>   tests/qemuxml2xmltest.c: Test XML handling for leases
> ---
>  docs/schemas/domain.rng                        |   22 ++++

Patch is incomplete - you need something in docs/formatdomain.html.in
before you can commit this.

> +++ b/docs/schemas/domain.rng
> @@ -586,6 +586,27 @@
>        <ref name="address"/>
>      </optional>
>    </define>
> +
> +  <define name="lease">
> +    <element name="lease">

<interleave>

> +      <element name="lockspace">
> +        <text/>
> +      </element>
> +      <element name="key">
> +        <text/>
> +      </element>
> +      <element name="target">
> +        <attribute name="path">
> +          <text/>
> +        </attribute>
> +        <optional>
> +          <attribute name="offset">
> +            <ref name="unsignedInt"/>
> +          </attribute>
> +        </optional>
> +      </element>

</interleave>

> +    </element>
> +  </define>

> +
> +    cur = node->children;
> +    while (cur != NULL) {
> +        if (cur->type == XML_ELEMENT_NODE) {
> +            if ((key == NULL) &&
> +                (xmlStrEqual(cur->name, BAD_CAST "key"))) {
> +                key = (char *)xmlNodeGetContent(cur);
> +            } else if ((lockspace == NULL) &&
> +                (xmlStrEqual(cur->name, BAD_CAST "lockspace"))) {
> +                lockspace = (char *)xmlNodeGetContent(cur);
> +            } else if ((path == NULL) &&
> +                       (xmlStrEqual(cur->name, BAD_CAST "target"))) {
> +                path = virXMLPropString(cur, "path");
> +                offset = virXMLPropString(cur, "offset");
> +            }

Do we want to reject unknown elements?  Here, you just silently ignore them.

> +++ b/tests/qemuxml2argvdata/qemuxml2argv-lease.args
> @@ -0,0 +1 @@
> +LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -hda /dev/HostVG/QEMUGuest1 -cdrom /root/boot.iso -net none -serial none -parallel none -usb

Please break this file up, using backslash-newline, so that it generally
fits in 80 columns.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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