storage: optional 'refresh' elemement on pool

The new 'refresh' element can override the default refresh operations
for a storage pool. The only currently supported override is to set
the volume allocation size to the volume capacity. This can be specified
by adding the following snippet:

<pool>
...
  <refresh>
    <volume allocation='capacity'/>
  </refresh>
...
</pool>

This is useful for certain backends where computing the actual allocation
of a volume might be an expensive operation.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatstorage.html.in

@@ -508,6 +508,32 @@
       device, measured in bytes.  <span class="since">Since 0.4.1</span>
     </p>
 
+    <h3><a id="StoragePoolRefresh">Refresh overrides</a></h3>
+
+    <p>
+      The optional <code>refresh</code> element can control how the pool and
+      associated volumes are refreshed (pool type <code>rbd</code>). The
+      <code>allocation</code> attribute of the <code>volume</code> child element
+      controls the method used for computing the allocation of a volume. The
+      valid attribute values are <code>default</code> to compute the actual
+      usage or <code>capacity</code> to use the logical capacity for cases where
+      computing the allocation is too expensive. The following XML snippet
+      shows the syntax:
+      <pre>
+&lt;pool type="rbd"&gt;
+  &lt;name&gt;myrbdpool&lt;/name&gt;
+...
+  &lt;source/&gt;
+...
+  &lt;refresh&gt;
+    &lt;volume allocation='capacity'/&gt;
+  &lt;/refresh&gt;
+...
+&lt;/pool&gt;
+</pre>
+      <span class="since">Since 5.2.0</span>
+    </p>
+
     <h3><a id="StoragePoolNamespaces">Storage Pool Namespaces</a></h3>
 
     <p>

docs/schemas/storagecommon.rng

@@ -236,4 +236,11 @@
     </optional>
   </define>
 
+  <define name='refreshVolumeAllocation'>
+    <choice>
+      <value>default</value>
+      <value>capacity</value>
+    </choice>
+  </define>
+
 </grammar>

docs/schemas/storagepool.rng

@@ -155,6 +155,7 @@
       <ref name='commonMetadataNameOptional'/>
       <ref name='sizing'/>
       <ref name='sourcerbd'/>
+      <ref name='refresh'/>
     </interleave>
     <optional>
       <ref name='rbd_config_opts'/>
@@ -691,6 +692,28 @@
     </data>
   </define>
 
+  <define name='refresh'>
+    <optional>
+      <element name='refresh'>
+        <interleave>
+          <ref name='refreshVolume'/>
+        </interleave>
+      </element>
+    </optional>
+  </define>
+
+  <define name='refreshVolume'>
+    <optional>
+      <element name='volume'>
+        <optional>
+          <attribute name='allocation'>
+            <ref name="refreshVolumeAllocation"/>
+          </attribute>
+        </optional>
+      </element>
+    </optional>
+  </define>
+
   <!--
        Optional storage pool extensions in their own namespace:
          "fs" or "netfs"

src/conf/storage_conf.c

@@ -94,6 +94,11 @@ VIR_ENUM_IMPL(virStorageVolFormatDisk,
               "extended",
 );
 
+VIR_ENUM_IMPL(virStorageVolDefRefreshAllocation,
+              VIR_STORAGE_VOL_DEF_REFRESH_ALLOCATION_LAST,
+              "default", "capacity",
+);
+
 VIR_ENUM_IMPL(virStoragePartedFs,
               VIR_STORAGE_PARTED_FS_TYPE_LAST,
               "ext2", "ext2", "fat16",
@@ -789,6 +794,51 @@ virStorageDefParsePerms(xmlXPathContextPtr ctxt,
 }
 
 
+static int
+virStoragePoolDefRefreshParse(xmlXPathContextPtr ctxt,
+                              virStoragePoolDefPtr def)
+{
+    VIR_AUTOFREE(virStoragePoolDefRefreshPtr) refresh = NULL;
+    VIR_AUTOFREE(char *) allocation = NULL;
+    int tmp;
+
+    allocation = virXPathString("string(./refresh/volume/@allocation)", ctxt);
+
+    if (!allocation)
+        return 0;
+
+    if ((tmp = virStorageVolDefRefreshAllocationTypeFromString(allocation)) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unknown storage pool volume refresh allocation type %s"),
+                       allocation);
+        return -1;
+    }
+
+    if (VIR_ALLOC(refresh) < 0)
+        return -1;
+
+    refresh->volume.allocation = tmp;
+    VIR_STEAL_PTR(def->refresh, refresh);
+    return 0;
+}
+
+
+static void
+virStoragePoolDefRefreshFormat(virBufferPtr buf,
+                               virStoragePoolDefRefreshPtr refresh)
+{
+    if (!refresh)
+        return;
+
+    virBufferAddLit(buf, "<refresh>\n");
+    virBufferAdjustIndent(buf, 2);
+    virBufferAsprintf(buf, "<volume allocation='%s'/>\n",
+                      virStorageVolDefRefreshAllocationTypeToString(refresh->volume.allocation));
+    virBufferAdjustIndent(buf, -2);
+    virBufferAddLit(buf, "</refresh>\n");
+}
+
+
 virStoragePoolDefPtr
 virStoragePoolDefParseXML(xmlXPathContextPtr ctxt)
 {
@@ -799,6 +849,7 @@ virStoragePoolDefParseXML(xmlXPathContextPtr ctxt)
     VIR_AUTOFREE(char *) type = NULL;
     VIR_AUTOFREE(char *) uuid = NULL;
     VIR_AUTOFREE(char *) target_path = NULL;
+    VIR_AUTOFREE(char *) refresh_volume_allocation = NULL;
 
     if (VIR_ALLOC(def) < 0)
         return NULL;
@@ -931,6 +982,9 @@ virStoragePoolDefParseXML(xmlXPathContextPtr ctxt)
         return NULL;
     }
 
+    if (virStoragePoolDefRefreshParse(ctxt, def) < 0)
+        return NULL;
+
     /* Make a copy of all the callback pointers here for easier use,
      * especially during the virStoragePoolSourceClear method */
     def->ns = options->ns;
@@ -1163,6 +1217,8 @@ virStoragePoolDefFormatBuf(virBufferPtr buf,
         virBufferAddLit(buf, "</target>\n");
     }
 
+    virStoragePoolDefRefreshFormat(buf, def->refresh);
+
     if (def->namespaceData && def->ns.format) {
         if ((def->ns.format)(buf, def->namespaceData) < 0)
             return -1;

src/conf/storage_conf.h

@@ -83,6 +83,13 @@ struct _virStorageVolSource {
                    * backend for partition type creation */
 };
 
+typedef enum {
+    VIR_STORAGE_VOL_DEF_REFRESH_ALLOCATION_DEFAULT,  /* compute actual allocation */
+    VIR_STORAGE_VOL_DEF_REFRESH_ALLOCATION_CAPACITY, /* use logical capacity */
+    VIR_STORAGE_VOL_DEF_REFRESH_ALLOCATION_LAST,
+} virStorageVolDefRefreshAllocation;
+
+VIR_ENUM_DECL(virStorageVolDefRefreshAllocation);
 
 typedef struct _virStorageVolDef virStorageVolDef;
 typedef virStorageVolDef *virStorageVolDefPtr;
@@ -236,6 +243,21 @@ struct _virStoragePoolTarget {
     virStoragePerms perms; /* Default permissions for volumes */
 };
 
+
+typedef struct _virStorageVolDefRefresh virStorageVolDefRefresh;
+typedef virStorageVolDefRefresh *virStorageVolDefRefreshPtr;
+struct _virStorageVolDefRefresh {
+  int allocation; /* virStorageVolDefRefreshAllocation */
+};
+
+
+typedef struct _virStoragePoolDefRefresh virStoragePoolDefRefresh;
+typedef virStoragePoolDefRefresh *virStoragePoolDefRefreshPtr;
+struct _virStoragePoolDefRefresh {
+  virStorageVolDefRefresh volume;
+};
+
+
 typedef struct _virStoragePoolDef virStoragePoolDef;
 typedef virStoragePoolDef *virStoragePoolDefPtr;
 struct _virStoragePoolDef {
@@ -243,6 +265,8 @@ struct _virStoragePoolDef {
     unsigned char uuid[VIR_UUID_BUFLEN];
     int type; /* virStoragePoolType */
 
+    virStoragePoolDefRefreshPtr refresh;
+
     unsigned long long allocation; /* bytes */
     unsigned long long capacity; /* bytes */
     unsigned long long available; /* bytes */

src/libvirt_private.syms

@@ -942,6 +942,8 @@ virStorageVolDefFree;
 virStorageVolDefParseFile;
 virStorageVolDefParseNode;
 virStorageVolDefParseString;
+virStorageVolDefRefreshAllocationTypeFromString;
+virStorageVolDefRefreshAllocationTypeToString;
 virStorageVolTypeFromString;
 virStorageVolTypeToString;
 

tests/storagepoolxml2xmlin/pool-rbd-refresh-volume-allocation.xml

@@ -0,0 +1,15 @@
+<pool type='rbd'>
+  <name>ceph</name>
+  <uuid>47c1faee-0207-e741-f5ae-d9b019b98fe2</uuid>
+  <source>
+    <name>rbd</name>
+    <host name='localhost' port='6789'/>
+    <host name='localhost' port='6790'/>
+    <auth username='admin' type='ceph'>
+      <secret uuid='2ec115d7-3a88-3ceb-bc12-0ac909a6fd87'/>
+    </auth>
+  </source>
+  <refresh>
+    <volume allocation='capacity'/>
+  </refresh>
+</pool>

tests/storagepoolxml2xmlout/pool-rbd-refresh-volume-allocation.xml

@@ -0,0 +1,18 @@
+<pool type='rbd'>
+  <name>ceph</name>
+  <uuid>47c1faee-0207-e741-f5ae-d9b019b98fe2</uuid>
+  <capacity unit='bytes'>0</capacity>
+  <allocation unit='bytes'>0</allocation>
+  <available unit='bytes'>0</available>
+  <source>
+    <host name='localhost' port='6789'/>
+    <host name='localhost' port='6790'/>
+    <name>rbd</name>
+    <auth type='ceph' username='admin'>
+      <secret uuid='2ec115d7-3a88-3ceb-bc12-0ac909a6fd87'/>
+    </auth>
+  </source>
+  <refresh>
+    <volume allocation='capacity'/>
+  </refresh>
+</pool>

tests/storagepoolxml2xmltest.c

@@ -95,6 +95,7 @@ mymain(void)
     DO_TEST("pool-zfs-sourcedev");
     DO_TEST("pool-rbd");
 #ifdef WITH_STORAGE_RBD
+    DO_TEST("pool-rbd-refresh-volume-allocation");
     DO_TEST("pool-rbd-ns-configopts");
 #endif
     DO_TEST("pool-vstorage");