storage: Introduce 'managed' for the fchost parent

https://bugzilla.redhat.com/show_bug.cgi?id=1160926

Introduce a 'managed' attribute to allow libvirt to decide whether to
delete a vHBA vport created via external means such as nodedev-create.
The code currently decides whether to delete the vHBA based solely on
whether the parent was provided at creation time. However, that may not
be the desired action, so rather than delete and force someone to create
another vHBA via an additional nodedev-create allow the configuration of
the storage pool to decide the desired action.

During createVport when libvirt does the VPORT_CREATE, set the managed
value to YES if not already set to indicate to the deleteVport code that
it should delete the vHBA when the pool is destroyed.

If libvirtd is restarted all the memory only state was lost, so for a
persistent storage pool, use the virStoragePoolSaveConfig in order to
write out the managed value.

Because we're now saving the current configuration, we need to be sure
to not save the parent in the output XML if it was undefined at start.
Saving the name would cause future starts to always use the same parent
which is not the expected result when not providing a parent. By not
providing a parent, libvirt is expected to find the best available
vHBA port for each subsequent (re)start.

At deleteVport, use the new managed value to decide whether to execute
the VPORT_DELETE.  Since we no longer save the parent in memory or in
XML when provided, if it was not provided, then we have to look it up.

docs/formatstorage.html.in

@@ -190,6 +190,19 @@
             defined for an existing scsi_host or by creating a vHBA.
             <span class="since">Since 1.0.4</span>
           </dd>
+          <dt><code>managed</code></dt>
+          <dd>An optional attribute to instruct the SCSI storage backend to
+            manage destroying the vHBA when the pool is destroyed. For
+            configurations that do not provide an already created vHBA
+            from a 'virsh nodedev-create', libvirt will set this property
+            to "yes". For configurations that have already created a vHBA
+            via 'virsh nodedev-create' and are using the wwnn/wwpn from
+            that vHBA and optionally the scsi_host parent, setting this
+            attribute to "yes" will allow libvirt to destroy the node device
+            when the pool is destroyed. If this attribute is set to "no" or
+            not defined in the XML, then libvirt will not destroy the vHBA.
+            <span class="since">Since 1.2.11</span>
+          </dd>
         </dl>
         <dl>
           <dt><code>parentaddr</code></dt>

docs/schemas/basictypes.rng

@@ -389,6 +389,11 @@
               <text/>
             </attribute>
           </optional>
+          <optional>
+            <attribute name='managed'>
+              <ref name="virYesNo"/>
+            </attribute>
+          </optional>
           <attribute name='wwnn'>
             <ref name='wwn'/>
           </attribute>

src/conf/storage_conf.c

@@ -475,6 +475,7 @@ virStoragePoolDefParseSource(xmlXPathContextPtr ctxt,
     char *name = NULL;
     char *port = NULL;
     char *adapter_type = NULL;
+    char *managed = NULL;
     int n;
 
     relnode = ctxt->node;
@@ -578,6 +579,18 @@ virStoragePoolDefParseSource(xmlXPathContextPtr ctxt,
             VIR_STORAGE_POOL_SOURCE_ADAPTER_TYPE_FC_HOST) {
             source->adapter.data.fchost.parent =
                 virXPathString("string(./adapter/@parent)", ctxt);
+            managed = virXPathString("string(./adapter/@managed)", ctxt);
+            if (managed) {
+                source->adapter.data.fchost.managed =
+                    virTristateBoolTypeFromString(managed);
+                if (source->adapter.data.fchost.managed < 0) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                                   _("unknown fc_host managed setting '%s'"),
+                                   managed);
+                    goto cleanup;
+                }
+            }
+
             source->adapter.data.fchost.wwnn =
                 virXPathString("string(./adapter/@wwnn)", ctxt);
             source->adapter.data.fchost.wwpn =
@@ -675,6 +688,7 @@ virStoragePoolDefParseSource(xmlXPathContextPtr ctxt,
     VIR_FREE(port);
     VIR_FREE(nodeset);
     VIR_FREE(adapter_type);
+    VIR_FREE(managed);
     virStorageAuthDefFree(authdef);
     return ret;
 }
@@ -1076,6 +1090,9 @@ virStoragePoolSourceFormat(virBufferPtr buf,
         if (src->adapter.type == VIR_STORAGE_POOL_SOURCE_ADAPTER_TYPE_FC_HOST) {
             virBufferEscapeString(buf, " parent='%s'",
                                   src->adapter.data.fchost.parent);
+            if (src->adapter.data.fchost.managed)
+                virBufferAsprintf(buf, " managed='%s'",
+                                  virTristateBoolTypeToString(src->adapter.data.fchost.managed));
             virBufferAsprintf(buf, " wwnn='%s' wwpn='%s'/>\n",
                               src->adapter.data.fchost.wwnn,
                               src->adapter.data.fchost.wwpn);

src/conf/storage_conf.h

@@ -192,6 +192,7 @@ struct _virStoragePoolSourceAdapter {
             char *parent;
             char *wwnn;
             char *wwpn;
+            int managed;        /* enum virTristateSwitch */
         } fchost;
     } data;
 };

src/storage/storage_backend_scsi.c

@@ -590,6 +590,9 @@ getVhbaSCSIHostParent(virConnectPtr conn,
     if (!(def = virNodeDeviceDefParseString(xml, EXISTING_DEVICE, NULL)))
         goto cleanup;
 
+    /* The caller checks whether the returned value is NULL or not
+     * before continuing
+     */
     ignore_value(VIR_STRDUP(vhba_parent, def->parent));
 
  cleanup:
@@ -644,15 +647,21 @@ checkVhbaSCSIHostParent(virConnectPtr conn,
 
 static int
 createVport(virConnectPtr conn,
+            const char *configFile,
             virStoragePoolDefPtr def)
 {
     virStoragePoolSourceAdapterPtr adapter = &def->source.adapter;
     unsigned int parent_host;
     char *name = NULL;
+    char *parent_hoststr = NULL;
 
     if (adapter->type != VIR_STORAGE_POOL_SOURCE_ADAPTER_TYPE_FC_HOST)
         return 0;
 
+    VIR_DEBUG("conn=%p, configFile='%s' parent='%s', wwnn='%s' wwpn='%s'",
+              conn, NULLSTR(configFile), NULLSTR(adapter->data.fchost.parent),
+              adapter->data.fchost.wwnn, adapter->data.fchost.wwpn);
+
     /* If a parent was provided, then let's make sure it's vhost capable */
     if (adapter->data.fchost.parent) {
         if (virGetSCSIHostNumber(adapter->data.fchost.parent, &parent_host) < 0)
@@ -687,17 +696,42 @@ createVport(virConnectPtr conn,
     }
 
     if (!adapter->data.fchost.parent) {
-        if (!(adapter->data.fchost.parent = virFindFCHostCapableVport(NULL))) {
+        if (!(parent_hoststr = virFindFCHostCapableVport(NULL))) {
             virReportError(VIR_ERR_XML_ERROR, "%s",
                            _("'parent' for vHBA not specified, and "
                              "cannot find one on this host"));
             return -1;
         }
 
-        if (virGetSCSIHostNumber(adapter->data.fchost.parent, &parent_host) < 0)
+        if (virGetSCSIHostNumber(parent_hoststr, &parent_host) < 0) {
+            VIR_FREE(parent_hoststr);
             return -1;
         }
 
+        /* NOTE:
+         * We do not save the parent_hoststr in adapter->data.fchost.parent
+         * since we could be writing out the 'def' to the saved XML config.
+         * If we wrote out the name in the XML, then future starts would
+         * always use the same parent rather than finding the "best available"
+         * parent. Besides we have a way to determine the parent based on
+         * the 'name' field.
+         */
+        VIR_FREE(parent_hoststr);
+    }
+
+    /* Since we're creating the vHBA, then we need to manage removing it
+     * as well. Since we need this setting to "live" through a libvirtd
+     * restart, we need to save the persistent configuration. So if not
+     * already defined as YES, then force the issue.
+     */
+    if (adapter->data.fchost.managed != VIR_TRISTATE_BOOL_YES) {
+        adapter->data.fchost.managed = VIR_TRISTATE_BOOL_YES;
+        if (configFile) {
+            if (virStoragePoolSaveConfig(configFile, def) < 0)
+                return -1;
+        }
+    }
+
     if (virManageVport(parent_host, adapter->data.fchost.wwpn,
                        adapter->data.fchost.wwnn, VPORT_CREATE) < 0)
         return -1;
@@ -707,29 +741,50 @@ createVport(virConnectPtr conn,
 }
 
 static int
-deleteVport(virStoragePoolSourceAdapter adapter)
+deleteVport(virConnectPtr conn,
+            virStoragePoolSourceAdapter adapter)
 {
     unsigned int parent_host;
     char *name = NULL;
+    char *vhba_parent = NULL;
     int ret = -1;
 
     if (adapter.type != VIR_STORAGE_POOL_SOURCE_ADAPTER_TYPE_FC_HOST)
         return 0;
 
-    /* It must be a HBA instead of a vHBA as long as "parent"
-     * is NULL. "createVport" guaranteed "parent" for a vHBA
-     * cannot be NULL, it's either specified in XML, or detected
-     * automatically.
-     */
-    if (!adapter.data.fchost.parent)
+    VIR_DEBUG("conn=%p parent='%s', managed='%d' wwnn='%s' wwpn='%s'",
+              conn, NULLSTR(adapter.data.fchost.parent),
+              adapter.data.fchost.managed,
+              adapter.data.fchost.wwnn,
+              adapter.data.fchost.wwpn);
+
+    /* If we're not managing the deletion of the vHBA, then just return */
+    if (adapter.data.fchost.managed != VIR_TRISTATE_BOOL_YES)
         return 0;
 
+    /* Find our vHBA by searching the fc_host sysfs tree for our wwnn/wwpn */
     if (!(name = virGetFCHostNameByWWN(NULL, adapter.data.fchost.wwnn,
-                                       adapter.data.fchost.wwpn)))
-        return -1;
+                                       adapter.data.fchost.wwpn))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Failed to find fc_host for wwnn='%s' and wwpn='%s'"),
+                       adapter.data.fchost.wwnn, adapter.data.fchost.wwpn);
+        goto cleanup;
+    }
 
+    /* If at startup time we provided a parent, then use that to
+     * get the parent_host value; otherwise, we have to determine
+     * the parent scsi_host which we did not save at startup time
+     */
+    if (adapter.data.fchost.parent) {
         if (virGetSCSIHostNumber(adapter.data.fchost.parent, &parent_host) < 0)
             goto cleanup;
+    } else {
+        if (!(vhba_parent = getVhbaSCSIHostParent(conn, name)))
+            goto cleanup;
+
+        if (virGetSCSIHostNumber(vhba_parent, &parent_host) < 0)
+            goto cleanup;
+    }
 
     if (virManageVport(parent_host, adapter.data.fchost.wwpn,
                        adapter.data.fchost.wwnn, VPORT_DELETE) < 0)
@@ -738,6 +793,7 @@ deleteVport(virStoragePoolSourceAdapter adapter)
     ret = 0;
  cleanup:
     VIR_FREE(name);
+    VIR_FREE(vhba_parent);
     return ret;
 }
 
@@ -817,15 +873,15 @@ static int
 virStorageBackendSCSIStartPool(virConnectPtr conn,
                                virStoragePoolObjPtr pool)
 {
-    return createVport(conn, pool->def);
+    return createVport(conn, pool->configFile, pool->def);
 }
 
 static int
-virStorageBackendSCSIStopPool(virConnectPtr conn ATTRIBUTE_UNUSED,
+virStorageBackendSCSIStopPool(virConnectPtr conn,
                               virStoragePoolObjPtr pool)
 {
     virStoragePoolSourceAdapter adapter = pool->def->source.adapter;
-    return deleteVport(adapter);
+    return deleteVport(conn, adapter);
 }
 
 virStorageBackend virStorageBackendSCSI = {

tests/storagepoolxml2xmlin/pool-scsi-type-fc-host-managed.xml

@@ -0,0 +1,15 @@
+<pool type='scsi'>
+  <name>hba0</name>
+  <uuid>e9392370-2917-565e-692b-d057f46512d6</uuid>
+  <source>
+    <adapter type='fc_host' parent='scsi_host5' managed='yes' wwnn='20000000c9831b4b' wwpn='10000000c9831b4b'/>
+  </source>
+  <target>
+    <path>/dev/disk/by-path</path>
+    <permissions>
+      <mode>0700</mode>
+      <owner>0</owner>
+      <group>0</group>
+    </permissions>
+  </target>
+</pool>

tests/storagepoolxml2xmlout/pool-scsi-type-fc-host-managed.xml

@@ -0,0 +1,18 @@
+<pool type='scsi'>
+  <name>hba0</name>
+  <uuid>e9392370-2917-565e-692b-d057f46512d6</uuid>
+  <capacity unit='bytes'>0</capacity>
+  <allocation unit='bytes'>0</allocation>
+  <available unit='bytes'>0</available>
+  <source>
+    <adapter type='fc_host' parent='scsi_host5' managed='yes' wwnn='20000000c9831b4b' wwpn='10000000c9831b4b'/>
+  </source>
+  <target>
+    <path>/dev/disk/by-path</path>
+    <permissions>
+      <mode>0700</mode>
+      <owner>0</owner>
+      <group>0</group>
+    </permissions>
+  </target>
+</pool>

tests/storagepoolxml2xmltest.c

@@ -98,6 +98,7 @@ mymain(void)
     DO_TEST("pool-scsi");
     DO_TEST("pool-scsi-type-scsi-host");
     DO_TEST("pool-scsi-type-fc-host");
+    DO_TEST("pool-scsi-type-fc-host-managed");
     DO_TEST("pool-mpath");
     DO_TEST("pool-iscsi-multiiqn");
     DO_TEST("pool-iscsi-vendor-product");