Introduce new XMLs to specify disk source using libvirt storage

With this patch, one can specify the disk source using libvirt
storage like:

  <disk type='volume' device='disk'>
    <driver name='qemu' type='raw' cache='none'/>
    <source pool='default' volume='fc18.img'/>
    <target dev='vdb' bus='virtio'/>
  </disk>

"seclabels" and "startupPolicy" are not supported for this new
disk type ("volume"). They will be supported in later patches.

docs/formatdomain.html.in:
  * Add documents for new XMLs
docs/schemas/domaincommon.rng:
  * Add rng for new XMLs;
src/conf/domain_conf.h:
  * New struct for 'volume' type disk source (virDomainDiskSourcePoolDef)
  * Add VIR_DOMAIN_DISK_TYPE_VOLUME for enum virDomainDiskType
src/conf/domain_conf.c:
  * New helper virDomainDiskSourcePoolDefParse to parse the 'volume'
    type disk source.
  * New helper virDomainDiskSourcePoolDefFree to free the source def
    if 'volume' type disk.
tests/qemuxml2argvdata/qemuxml2argv-disk-source-pool.xml:
tests/qemuxml2xmltest.c:
  * New test

docs/formatdomain.html.in

@@ -1372,6 +1372,11 @@
       <blockio logical_block_size='512' physical_block_size='4096'/>
       <target dev='hda' bus='ide'/>
     </disk>
+    <disk type='volume' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source pool='blk-pool0' volume='blk-pool0-vol0'/>
+      <target dev='hda' bus='ide'/>
+    </disk>
   </devices>
   ...</pre>
 
@@ -1452,10 +1457,16 @@
         <code>iqn.1992-01.com.example/1</code>); the default LUN is zero.
         When the disk <code>type</code> is "network", the <code>source</code>
         may have zero or more <code>host</code> sub-elements used to
-        specify the hosts to connect.
+        specify the hosts to connect.  If the disk <code>type</code> is
+        "volume", the underlying disk source is represented by attributes
+        <code>pool</code> and <code>volume</code>. Attribute <code>pool</code>
+        specifies the name of storage pool (managed by libvirt) where the disk
+        source resides, and attribute <code>volume</code> specifies the name of
+        storage volume (managed by libvirt) used as the disk source.
         <span class="since">Since 0.0.3; <code>type='dir'</code> since
         0.7.5; <code>type='network'</code> since
-        0.8.7; <code>protocol='iscsi'</code> since 1.0.4</span><br/>
+        0.8.7; <code>protocol='iscsi'</code> since 1.0.4;
+        <code>type='volume'</code> since 1.0.5;</span><br/>
         For a "file" disk type which represents a cdrom or floppy
         (the <code>device</code> attribute), it is possible to define
         policy what to do with the disk if the source file is not accessible.

docs/schemas/domaincommon.rng

@@ -1107,6 +1107,24 @@
             <ref name="diskspec"/>
           </interleave>
         </group>
+        <group>
+          <attribute name="type">
+            <value>volume</value>
+          </attribute>
+          <interleave>
+            <optional>
+              <element name="source">
+                <attribute name="pool">
+                  <ref name="genericName"/>
+                </attribute>
+                <attribute name="volume">
+                  <ref name="volName"/>
+                </attribute>
+              </element>
+            </optional>
+            <ref name="diskspec"/>
+          </interleave>
+        </group>
         <ref name="diskspec"/>
       </choice>
     </element>

src/conf/domain_conf.c

@@ -210,7 +210,8 @@ VIR_ENUM_IMPL(virDomainDisk, VIR_DOMAIN_DISK_TYPE_LAST,
               "block",
               "file",
               "dir",
-              "network")
+              "network",
+              "volume")
 
 VIR_ENUM_IMPL(virDomainDiskDevice, VIR_DOMAIN_DISK_DEVICE_LAST,
               "disk",
@@ -1116,6 +1117,18 @@ void virDomainLeaseDefFree(virDomainLeaseDefPtr def)
     VIR_FREE(def);
 }
 
+static void
+virDomainDiskSourcePoolDefFree(virDomainDiskSourcePoolDefPtr def)
+{
+    if (!def)
+        return;
+
+    VIR_FREE(def->pool);
+    VIR_FREE(def->volume);
+
+    VIR_FREE(def);
+}
+
 void virDomainDiskDefFree(virDomainDiskDefPtr def)
 {
     unsigned int i;
@@ -1125,6 +1138,7 @@ void virDomainDiskDefFree(virDomainDiskDefPtr def)
 
     VIR_FREE(def->serial);
     VIR_FREE(def->src);
+    virDomainDiskSourcePoolDefFree(def->srcpool);
     VIR_FREE(def->dst);
     VIR_FREE(def->driverName);
     virStorageFileFreeMetadata(def->backingChain);
@@ -4157,6 +4171,46 @@ cleanup:
     goto cleanup;
 }
 
+static int
+virDomainDiskSourcePoolDefParse(xmlNodePtr node,
+                                virDomainDiskDefPtr def)
+{
+    char *pool = NULL;
+    char *volume = NULL;
+    int ret = -1;
+
+    pool = virXMLPropString(node, "pool");
+    volume = virXMLPropString(node, "volume");
+
+    /* CD-ROM and Floppy allows no source */
+    if (!pool && !volume)
+        return 0;
+
+    if (!pool || !volume) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("'pool' and 'volume' must be specified together "
+                         "for 'pool' type source"));
+        goto cleanup;
+    }
+
+    if (VIR_ALLOC(def->srcpool) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
+
+    def->srcpool->pool = pool;
+    pool = NULL;
+    def->srcpool->volume = volume;
+    volume = NULL;
+
+    ret = 0;
+
+cleanup:
+    VIR_FREE(pool);
+    VIR_FREE(volume);
+    return ret;
+}
+
 #define VENDOR_LEN  8
 #define PRODUCT_LEN 16
 
@@ -4252,7 +4306,7 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
     cur = node->children;
     while (cur != NULL) {
         if (cur->type == XML_ELEMENT_NODE) {
-            if (!source && !hosts &&
+            if (!source && !hosts && !def->srcpool &&
                 xmlStrEqual(cur->name, BAD_CAST "source")) {
                 sourceNode = cur;
 
@@ -4345,6 +4399,10 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
                         child = child->next;
                     }
                     break;
+                case VIR_DOMAIN_DISK_TYPE_VOLUME:
+                    if (virDomainDiskSourcePoolDefParse(cur, def) < 0)
+                        goto error;
+                    break;
                 default:
                     virReportError(VIR_ERR_INTERNAL_ERROR,
                                    _("unexpected disk type %s"),
@@ -4643,7 +4701,7 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
 
     /* Only CDROM and Floppy devices are allowed missing source path
      * to indicate no media present */
-    if (source == NULL && hosts == NULL &&
+    if (source == NULL && hosts == NULL && !def->srcpool &&
         def->device != VIR_DOMAIN_DISK_DEVICE_CDROM &&
         def->device != VIR_DOMAIN_DISK_DEVICE_FLOPPY) {
         virReportError(VIR_ERR_NO_SOURCE,
@@ -4665,8 +4723,19 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
     }
 
     if (target == NULL) {
-        virReportError(VIR_ERR_NO_TARGET,
-                       source ? "%s" : NULL, source);
+        if (def->srcpool) {
+            char *tmp;
+            if (virAsprintf(&tmp, "pool = '%s', volume = '%s'",
+                def->srcpool->pool, def->srcpool->volume) < 0) {
+                virReportOOMError();
+                goto error;
+            }
+
+            virReportError(VIR_ERR_NO_TARGET, "%s", tmp);
+            VIR_FREE(tmp);
+        } else {
+            virReportError(VIR_ERR_NO_TARGET, source ? "%s" : NULL, source);
+        }
         goto error;
     }
 
@@ -12877,7 +12946,7 @@ virDomainDiskSourceDefFormat(virBufferPtr buf,
     int n;
     const char *startupPolicy = virDomainStartupPolicyTypeToString(def->startupPolicy);
 
-    if (def->src || def->nhosts > 0 ||
+    if (def->src || def->nhosts > 0 || def->srcpool ||
         def->startupPolicy) {
         switch (def->type) {
         case VIR_DOMAIN_DISK_TYPE_FILE:
@@ -12949,6 +13018,14 @@ virDomainDiskSourceDefFormat(virBufferPtr buf,
                 virBufferAddLit(buf, "      </source>\n");
             }
             break;
+        case VIR_DOMAIN_DISK_TYPE_VOLUME:
+            /* Parsing guarantees the def->srcpool->volume cannot be NULL
+             * if def->srcpool->pool is not NULL.
+             */
+            if (def->srcpool->pool)
+                virBufferAsprintf(buf, "      <source pool='%s' volume='%s'/>\n",
+                                  def->srcpool->pool, def->srcpool->volume);
+            break;
         default:
             virReportError(VIR_ERR_INTERNAL_ERROR,
                            _("unexpected disk type %s"),

src/conf/domain_conf.h

@@ -447,6 +447,7 @@ enum virDomainDiskType {
     VIR_DOMAIN_DISK_TYPE_FILE,
     VIR_DOMAIN_DISK_TYPE_DIR,
     VIR_DOMAIN_DISK_TYPE_NETWORK,
+    VIR_DOMAIN_DISK_TYPE_VOLUME,
 
     VIR_DOMAIN_DISK_TYPE_LAST
 };
@@ -606,6 +607,13 @@ struct _virDomainBlockIoTuneInfo {
 };
 typedef virDomainBlockIoTuneInfo *virDomainBlockIoTuneInfoPtr;
 
+typedef struct _virDomainDiskSourcePoolDef virDomainDiskSourcePoolDef;
+struct _virDomainDiskSourcePoolDef {
+    char *pool; /* pool name */
+    char *volume; /* volume name */
+};
+typedef virDomainDiskSourcePoolDef *virDomainDiskSourcePoolDefPtr;
+
 /* Stores the virtual disk configuration */
 struct _virDomainDiskDef {
     int type;
@@ -617,6 +625,7 @@ struct _virDomainDiskDef {
     int protocol;
     size_t nhosts;
     virDomainDiskHostDefPtr hosts;
+    virDomainDiskSourcePoolDefPtr srcpool;
     struct {
         char *username;
         int secretType; /* enum virDomainDiskSecretType */

tests/qemuxml2argvdata/qemuxml2argv-disk-source-pool.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='volume' device='cdrom'>
+      <source pool='blk-pool0' volume='blk-pool0-vol0'/>
+      <target dev='hda' bus='ide'/>
+      <readonly/>
+      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
+    </disk>
+    <disk type='file' device='disk'>
+      <source file='/tmp/idedisk.img'/>
+      <target dev='hdc' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='2'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='ide' index='1'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -253,6 +253,7 @@ mymain(void)
     DO_TEST("disk-scsi-lun-passthrough-sgio");
 
     DO_TEST("disk-scsi-disk-vpd");
+    DO_TEST("disk-source-pool");
 
     DO_TEST("virtio-rng-random");
     DO_TEST("virtio-rng-egd");