virstoragefile: Introduce virStoragePRDef

This is a definition that holds information on SCSI persistent
reservation settings. The XML part looks like this:

  <reservations enabled='yes' managed='no'>
    <source type='unix' path='/path/to/qemu-pr-helper.sock' mode='client'/>
  </reservations>

If @managed is set to 'yes' then the <source/> is not parsed.
This design was agreed on here:

https://www.redhat.com/archives/libvir-list/2017-November/msg01005.html

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>

docs/formatdomain.html.in

@@ -2566,7 +2566,10 @@
   </disk>
   <disk type='block' device='lun'>
     <driver name='qemu' type='raw'/>
-    <source dev='/dev/sda'/>
+    <source dev='/dev/sda'>
+      <reservations enabled='yes' managed='no'>
+        <source type='unix' path='/path/to/qemu-pr-helper' mode='client'/>
+      </reservations>
     <target dev='sda' bus='scsi'/>
     <address type='drive' controller='0' bus='0' target='3' unit='0'/>
   </disk>
@@ -2929,6 +2932,26 @@
             <a href="formatstorageencryption.html">Storage Encryption</a>
             page for more information.
           </dd>
+          <dt><code>reservations</code></dt>
+          <dd><span class="since">Since libvirt 4.4.0</span>, the
+            <code>reservations</code> can be a sub-element of the
+            <code>source</code> element for storage sources (QEMU driver only).
+            If present (and enabled) it enables persistent reservations for SCSI
+            based disks. The element has one mandatory attribute
+            <code>enabled</code> with accepted values <code>yes</code> and
+            <code>no</code>. If the feature is enabled, then there's another
+            mandatory attribute <code>managed</code> (accepted values are the
+            same as for <code>enabled</code>) that enables or disables libvirt
+            spawning a helper process. When the PR is unmanaged, then hypervisor
+            acts as a client and path to server socket must be provided in child
+            element <code>source</code>, which currently accepts only the
+            following attributes: <code>type</code> with one value
+            <code>unix</code>, <code>path</code> with path the socket, and
+            finally <code>mode</code> which accepts one value
+            <code>client</code> and specifies the role of hypervisor.
+            It's recommended to allow libvirt manage the persistent
+            reservations.
+          </dd>
         </dl>
 
         <p>

docs/schemas/domaincommon.rng

@@ -1530,6 +1530,9 @@
         <optional>
           <ref name="encryption"/>
         </optional>
+        <optional>
+          <ref name="reservations"/>
+        </optional>
         <zeroOrMore>
           <ref name='devSeclabel'/>
         </zeroOrMore>
@@ -2434,18 +2437,6 @@
       </attribute>
     </optional>
   </define>
-  <define name="reconnect">
-    <element name="reconnect">
-      <attribute name="enabled">
-        <ref name="virYesNo"/>
-      </attribute>
-      <optional>
-        <attribute name="timeout">
-          <ref name="unsignedInt"/>
-        </attribute>
-      </optional>
-    </element>
-  </define>
 
   <!--
       An interface description can either be of type bridge in which case
@@ -2494,24 +2485,7 @@
             <value>vhostuser</value>
           </attribute>
           <interleave>
-            <element name="source">
+            <ref name="unixSocketSource"/>
-              <attribute name="type">
-                <value>unix</value>
-              </attribute>
-              <attribute name="path">
-                <ref name="absFilePath"/>
-              </attribute>
-              <attribute name="mode">
-                <choice>
-                  <value>server</value>
-                  <value>client</value>
-                </choice>
-              </attribute>
-              <optional>
-                 <ref name="reconnect"/>
-              </optional>
-              <empty/>
-            </element>
             <ref name="interface-options"/>
           </interleave>
         </group>

docs/schemas/storagecommon.rng

@@ -39,6 +39,56 @@
     </element>
   </define>
 
+  <define name="reconnect">
+    <element name="reconnect">
+      <attribute name="enabled">
+        <ref name="virYesNo"/>
+      </attribute>
+      <optional>
+        <attribute name="timeout">
+          <ref name="unsignedInt"/>
+        </attribute>
+      </optional>
+    </element>
+  </define>
+
+  <define name='unixSocketSource'>
+    <element name="source">
+      <attribute name="type">
+        <value>unix</value>
+      </attribute>
+      <attribute name="path">
+        <ref name="absFilePath"/>
+      </attribute>
+      <attribute name="mode">
+        <choice>
+          <value>server</value>
+          <value>client</value>
+        </choice>
+      </attribute>
+      <optional>
+         <ref name="reconnect"/>
+      </optional>
+      <empty/>
+    </element>
+  </define>
+
+  <define name='reservations'>
+    <element name='reservations'>
+      <attribute name='enabled'>
+        <ref name='virYesNo'/>
+      </attribute>
+      <optional>
+        <attribute name='managed'>
+          <ref name='virYesNo'/>
+        </attribute>
+      </optional>
+      <optional>
+        <ref name='unixSocketSource'/>
+      </optional>
+    </element>
+  </define>
+
   <define name='secret'>
     <element name='secret'>
       <attribute name='type'>

src/conf/domain_conf.c

@@ -5206,6 +5206,13 @@ virDomainDiskDefValidate(const virDomainDiskDef *disk)
         }
     }
 
+    if (disk->src->pr &&
+        disk->device != VIR_DOMAIN_DISK_DEVICE_LUN) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("<reservations/> allowed only for lun devices"));
+        return -1;
+    }
+
     /* Reject disks with a bus type that is not compatible with the
      * given address type. The function considers only buses that are
      * handled in common code. For other bus types it's not possible
@@ -8632,6 +8639,31 @@ virDomainDiskSourcePrivateDataParse(xmlNodePtr node,
 }
 
 
+static int
+virDomainDiskSourcePRParse(xmlNodePtr node,
+                           xmlXPathContextPtr ctxt,
+                           virStoragePRDefPtr *pr)
+{
+    xmlNodePtr saveNode = ctxt->node;
+    int ret = -1;
+
+    ctxt->node = node;
+
+    if (!(ctxt->node = virXPathNode("./reservations", ctxt))) {
+        ret = 0;
+        goto cleanup;
+    }
+
+    if (!(*pr = virStoragePRDefParseXML(ctxt)))
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    ctxt->node = saveNode;
+    return ret;
+}
+
+
 static int
 virDomainStorageSourceParse(xmlNodePtr node,
                             xmlXPathContextPtr ctxt,
@@ -8678,6 +8710,9 @@ virDomainStorageSourceParse(xmlNodePtr node,
         !(src->encryption = virStorageEncryptionParseNode(tmp, ctxt)))
         goto cleanup;
 
+    if (virDomainDiskSourcePRParse(node, ctxt, &src->pr) < 0)
+        goto cleanup;
+
     if (virSecurityDeviceLabelDefParseXML(&src->seclabels, &src->nseclabels,
                                           ctxt, flags) < 0)
         goto cleanup;
@@ -22953,6 +22988,9 @@ virDomainStorageSourceFormat(virBufferPtr attrBuf,
         virStorageEncryptionFormat(childBuf, src->encryption) < 0)
         return -1;
 
+    if (src->pr)
+        virStoragePRDefFormat(childBuf, src->pr);
+
     return 0;
 }
 

src/libvirt_private.syms

@@ -2801,6 +2801,9 @@ virStorageNetHostDefFree;
 virStorageNetHostTransportTypeFromString;
 virStorageNetHostTransportTypeToString;
 virStorageNetProtocolTypeToString;
+virStoragePRDefFormat;
+virStoragePRDefFree;
+virStoragePRDefParseXML;
 virStorageSourceBackingStoreClear;
 virStorageSourceClear;
 virStorageSourceCopy;

src/util/virstoragefile.c

@@ -1892,6 +1892,136 @@ virStorageAuthDefFormat(virBufferPtr buf,
 }
 
 
+void
+virStoragePRDefFree(virStoragePRDefPtr prd)
+{
+    if (!prd)
+        return;
+
+    VIR_FREE(prd->path);
+    VIR_FREE(prd);
+}
+
+
+virStoragePRDefPtr
+virStoragePRDefParseXML(xmlXPathContextPtr ctxt)
+{
+    virStoragePRDefPtr prd, ret = NULL;
+    char *enabled = NULL;
+    char *managed = NULL;
+    char *type = NULL;
+    char *path = NULL;
+    char *mode = NULL;
+
+    if (VIR_ALLOC(prd) < 0)
+        return NULL;
+
+    if (!(enabled = virXPathString("string(./@enabled)", ctxt))) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("missing @enabled attribute for <reservations/>"));
+        goto cleanup;
+    }
+
+    if ((prd->enabled = virTristateBoolTypeFromString(enabled)) <= 0) {
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("invalid value for 'enabled': %s"), enabled);
+        goto cleanup;
+    }
+
+    if (prd->enabled == VIR_TRISTATE_BOOL_YES) {
+        if (!(managed = virXPathString("string(./@managed)", ctxt))) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("missing @managed attribute for <reservations/>"));
+            goto cleanup;
+        }
+
+        if ((prd->managed = virTristateBoolTypeFromString(managed)) <= 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("invalid value for 'managed': %s"), managed);
+            goto cleanup;
+        }
+
+        if (prd->managed == VIR_TRISTATE_BOOL_NO) {
+            type = virXPathString("string(./source[1]/@type)", ctxt);
+            path = virXPathString("string(./source[1]/@path)", ctxt);
+            mode = virXPathString("string(./source[1]/@mode)", ctxt);
+
+            if (!type) {
+                virReportError(VIR_ERR_XML_ERROR, "%s",
+                               _("missing connection type for <reservations/>"));
+                goto cleanup;
+            }
+
+            if (!path) {
+                virReportError(VIR_ERR_XML_ERROR, "%s",
+                               _("missing path for <reservations/>"));
+                goto cleanup;
+            }
+
+            if (!mode) {
+                virReportError(VIR_ERR_XML_ERROR, "%s",
+                               _("missing connection mode for <reservations/>"));
+                goto cleanup;
+            }
+
+            if (STRNEQ(type, "unix")) {
+                virReportError(VIR_ERR_XML_ERROR,
+                               _("unsupported connection type for <reservations/>: %s"),
+                               type);
+                goto cleanup;
+            }
+
+            if (STRNEQ(mode, "client")) {
+                virReportError(VIR_ERR_XML_ERROR,
+                               _("unsupported connection mode for <reservations/>: %s"),
+                               mode);
+                goto cleanup;
+            }
+
+            VIR_STEAL_PTR(prd->path, path);
+        }
+    }
+
+    ret = prd;
+    prd = NULL;
+
+ cleanup:
+    VIR_FREE(mode);
+    VIR_FREE(path);
+    VIR_FREE(type);
+    VIR_FREE(managed);
+    VIR_FREE(enabled);
+    virStoragePRDefFree(prd);
+    return ret;
+}
+
+
+void
+virStoragePRDefFormat(virBufferPtr buf,
+                      virStoragePRDefPtr prd)
+{
+    virBufferAsprintf(buf, "<reservations enabled='%s'",
+                      virTristateBoolTypeToString(prd->enabled));
+    if (prd->enabled == VIR_TRISTATE_BOOL_YES) {
+        virBufferAsprintf(buf, " managed='%s'",
+                          virTristateBoolTypeToString(prd->managed));
+        if (prd->managed == VIR_TRISTATE_BOOL_NO) {
+            virBufferAddLit(buf, ">\n");
+            virBufferAdjustIndent(buf, 2);
+            virBufferAddLit(buf, "<source type='unix'");
+            virBufferEscapeString(buf, " path='%s'", prd->path);
+            virBufferAddLit(buf, " mode='client'/>\n");
+            virBufferAdjustIndent(buf, -2);
+            virBufferAddLit(buf, "</reservations>\n");
+        } else {
+            virBufferAddLit(buf, "/>\n");
+        }
+    } else {
+        virBufferAddLit(buf, "/>\n");
+    }
+}
+
+
 virSecurityDeviceLabelDefPtr
 virStorageSourceGetSecurityLabelDef(virStorageSourcePtr src,
                                     const char *model)
@@ -2268,6 +2398,7 @@ virStorageSourceClear(virStorageSourcePtr def)
     virBitmapFree(def->features);
     VIR_FREE(def->compat);
     virStorageEncryptionFree(def->encryption);
+    virStoragePRDefFree(def->pr);
     virStorageSourceSeclabelsClear(def);
     virStoragePermsFree(def->perms);
     VIR_FREE(def->timestamps);

src/util/virstoragefile.h

@@ -216,6 +216,14 @@ struct _virStorageAuthDef {
     virSecretLookupTypeDef seclookupdef;
 };
 
+typedef struct _virStoragePRDef virStoragePRDef;
+typedef virStoragePRDef *virStoragePRDefPtr;
+struct _virStoragePRDef {
+    int enabled; /* enum virTristateBool */
+    int managed; /* enum virTristateBool */
+    char *path;
+};
+
 typedef struct _virStorageDriverData virStorageDriverData;
 typedef virStorageDriverData *virStorageDriverDataPtr;
 
@@ -243,6 +251,7 @@ struct _virStorageSource {
     bool authInherited;
     virStorageEncryptionPtr encryption;
     bool encryptionInherited;
+    virStoragePRDefPtr pr;
 
     virObjectPtr privateData;
 
@@ -382,6 +391,11 @@ virStorageAuthDefPtr virStorageAuthDefParse(xmlNodePtr node,
                                             xmlXPathContextPtr ctxt);
 void virStorageAuthDefFormat(virBufferPtr buf, virStorageAuthDefPtr authdef);
 
+void virStoragePRDefFree(virStoragePRDefPtr prd);
+virStoragePRDefPtr virStoragePRDefParseXML(xmlXPathContextPtr ctxt);
+void virStoragePRDefFormat(virBufferPtr buf,
+                           virStoragePRDefPtr prd);
+
 virSecurityDeviceLabelDefPtr
 virStorageSourceGetSecurityLabelDef(virStorageSourcePtr src,
                                     const char *model);

tests/qemuxml2argvdata/disk-virtio-scsi-reservations.xml

@@ -0,0 +1,49 @@
+<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'>8</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-system-i686</emulator>
+    <disk type='block' device='lun'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'>
+        <reservations enabled='yes' managed='yes'/>
+      </source>
+      <target dev='sda' bus='scsi'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <disk type='block' device='lun'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest2'>
+        <reservations enabled='yes' managed='no'>
+          <source type='unix' path='/path/to/qemu-pr-helper.sock' mode='client'/>
+        </reservations>
+      </source>
+      <target dev='sdb' bus='scsi'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
+    </disk>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='scsi' index='0' model='virtio-scsi'>
+      <driver queues='8'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+    </memballoon>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/disk-virtio-scsi-reservations.xml

@@ -0,0 +1 @@
+../qemuxml2argvdata/disk-virtio-scsi-reservations.xml

tests/qemuxml2xmltest.c

@@ -387,6 +387,8 @@ mymain(void)
             QEMU_CAPS_VIRTIO_SCSI);
     DO_TEST("disk-virtio-scsi-num_queues",
             QEMU_CAPS_VIRTIO_SCSI);
+    DO_TEST("disk-virtio-scsi-reservations",
+            QEMU_CAPS_VIRTIO_SCSI);
     DO_TEST("disk-virtio-scsi-cmd_per_lun",
             QEMU_CAPS_VIRTIO_SCSI);
     DO_TEST("disk-virtio-scsi-max_sectors",