storage: export virStoragePoolLookupByTargetPath as a public API

The storagePoolLookupByTargetPath() method in the storage driver is used
by the QEMU driver during block migration. If there's a valid use case
for this in the QEMU driver, then external apps likely have similar
needs. Exposing it in the public API removes the direct dependancy from
the QEMU driver to the storage driver.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

include/libvirt/libvirt-storage.h

@@ -264,6 +264,8 @@ virStoragePoolPtr       virStoragePoolLookupByUUID      (virConnectPtr conn,
 virStoragePoolPtr       virStoragePoolLookupByUUIDString(virConnectPtr conn,
                                                          const char *uuid);
 virStoragePoolPtr       virStoragePoolLookupByVolume    (virStorageVolPtr vol);
+virStoragePoolPtr       virStoragePoolLookupByTargetPath(virConnectPtr conn,
+                                                         const char *path);
 
 /*
  * Creating/destroying pools

src/driver-storage.h

@@ -63,6 +63,10 @@ typedef virStoragePoolPtr
 typedef virStoragePoolPtr
 (*virDrvStoragePoolLookupByVolume)(virStorageVolPtr vol);
 
+typedef virStoragePoolPtr
+(*virDrvStoragePoolLookupByTargetPath)(virConnectPtr conn,
+                                       const char *path);
+
 typedef virStoragePoolPtr
 (*virDrvStoragePoolCreateXML)(virConnectPtr conn,
                               const char *xmlDesc,
@@ -236,6 +240,7 @@ struct _virStorageDriver {
     virDrvStoragePoolLookupByName storagePoolLookupByName;
     virDrvStoragePoolLookupByUUID storagePoolLookupByUUID;
     virDrvStoragePoolLookupByVolume storagePoolLookupByVolume;
+    virDrvStoragePoolLookupByTargetPath storagePoolLookupByTargetPath;
     virDrvStoragePoolCreateXML storagePoolCreateXML;
     virDrvStoragePoolDefineXML storagePoolDefineXML;
     virDrvStoragePoolBuild storagePoolBuild;

src/libvirt-storage.c

@@ -497,6 +497,46 @@ virStoragePoolLookupByVolume(virStorageVolPtr vol)
 }
 
 
+/**
+ * virStoragePoolLookupByTargetPath:
+ * @conn: pointer to hypervisor connection
+ * @path: path at which the pool is exposed
+ *
+ * Fetch a storage pool which maps to a particular target directory.
+ * If more than one pool maps to the path, it is undefined which
+ * will be returned first.
+ *
+ * virStoragePoolFree should be used to free the resources after the
+ * storage pool object is no longer needed.
+ *
+ * Returns a virStoragePoolPtr object, or NULL if no matching pool is found
+ */
+virStoragePoolPtr
+virStoragePoolLookupByTargetPath(virConnectPtr conn,
+                                 const char *path)
+{
+    VIR_DEBUG("conn=%p, path=%s", conn, NULLSTR(path));
+
+    virResetLastError();
+
+    virCheckConnectReturn(conn, NULL);
+    virCheckNonNullArgGoto(path, error);
+
+    if (conn->storageDriver && conn->storageDriver->storagePoolLookupByTargetPath) {
+        virStoragePoolPtr ret;
+        ret = conn->storageDriver->storagePoolLookupByTargetPath(conn, path);
+        if (!ret)
+            goto error;
+        return ret;
+    }
+
+    virReportUnsupportedError();
+
+ error:
+    virDispatchError(conn);
+    return NULL;
+}
+
 /**
  * virStoragePoolCreateXML:
  * @conn: pointer to hypervisor connection

src/libvirt_public.syms

@@ -779,4 +779,10 @@ LIBVIRT_3.9.0 {
     global:
         virDomainSetLifecycleAction;
 } LIBVIRT_3.7.0;
+
+LIBVIRT_4.1.0 {
+    global:
+        virStoragePoolLookupByTargetPath;
+} LIBVIRT_3.9.0;
+
 # .... define new API here using predicted next version number ....

src/qemu/qemu_migration.c

@@ -329,7 +329,7 @@ qemuMigrationPrecreateDisk(virConnectPtr conn,
         *volName = '\0';
         volName++;
 
-        if (!(pool = storagePoolLookupByTargetPath(conn, basePath)))
+        if (!(pool = virStoragePoolLookupByTargetPath(conn, basePath)))
             goto cleanup;
         format = virStorageFileFormatTypeToString(disk->src->format);
         if (disk->src->format == VIR_STORAGE_FILE_QCOW2)

src/remote/remote_driver.c

@@ -8556,6 +8556,7 @@ static virStorageDriver storage_driver = {
     .storagePoolLookupByName = remoteStoragePoolLookupByName, /* 0.4.1 */
     .storagePoolLookupByUUID = remoteStoragePoolLookupByUUID, /* 0.4.1 */
     .storagePoolLookupByVolume = remoteStoragePoolLookupByVolume, /* 0.4.1 */
+    .storagePoolLookupByTargetPath = remoteStoragePoolLookupByTargetPath, /* 4.1.0 */
     .storagePoolCreateXML = remoteStoragePoolCreateXML, /* 0.4.1 */
     .storagePoolDefineXML = remoteStoragePoolDefineXML, /* 0.4.1 */
     .storagePoolBuild = remoteStoragePoolBuild, /* 0.4.1 */

src/remote/remote_protocol.x

@@ -1761,6 +1761,14 @@ struct remote_storage_pool_lookup_by_volume_ret {
     remote_nonnull_storage_pool pool;
 };
 
+struct remote_storage_pool_lookup_by_target_path_args {
+    remote_nonnull_string path;
+};
+
+struct remote_storage_pool_lookup_by_target_path_ret {
+    remote_nonnull_storage_pool pool;
+};
+
 struct remote_storage_pool_create_xml_args {
     remote_nonnull_string xml;
     unsigned int flags;
@@ -6120,5 +6128,12 @@ enum remote_procedure {
      * @generate: both
      * @acl: domain:write
      */
-    REMOTE_PROC_DOMAIN_SET_LIFECYCLE_ACTION = 390
+    REMOTE_PROC_DOMAIN_SET_LIFECYCLE_ACTION = 390,
+
+    /**
+     * @generate: both
+     * @priority: high
+     * @acl: storage_pool:getattr
+     */
+    REMOTE_PROC_STORAGE_POOL_LOOKUP_BY_TARGET_PATH = 391
 };

src/remote_protocol-structs

@@ -1330,6 +1330,12 @@ struct remote_storage_pool_lookup_by_volume_args {
 struct remote_storage_pool_lookup_by_volume_ret {
         remote_nonnull_storage_pool pool;
 };
+struct remote_storage_pool_lookup_by_target_path_args {
+        remote_nonnull_string      path;
+};
+struct remote_storage_pool_lookup_by_target_path_ret {
+        remote_nonnull_storage_pool pool;
+};
 struct remote_storage_pool_create_xml_args {
         remote_nonnull_string      xml;
         u_int                      flags;
@@ -3262,4 +3268,5 @@ enum remote_procedure {
         REMOTE_PROC_DOMAIN_MANAGED_SAVE_GET_XML_DESC = 388,
         REMOTE_PROC_DOMAIN_MANAGED_SAVE_DEFINE_XML = 389,
         REMOTE_PROC_DOMAIN_SET_LIFECYCLE_ACTION = 390,
+        REMOTE_PROC_STORAGE_POOL_LOOKUP_BY_TARGET_PATH = 391,
 };

src/storage/storage_driver.c

@@ -1694,6 +1694,9 @@ storagePoolLookupByTargetPath(virConnectPtr conn,
                                            storagePoolLookupByTargetPathCallback,
                                            cleanpath))) {
         def = virStoragePoolObjGetDef(obj);
+        if (virStoragePoolLookupByTargetPathEnsureACL(conn, def) < 0)
+            goto cleanup;
+
         pool = virGetStoragePool(conn, def->name, def->uuid, NULL, NULL);
         virStoragePoolObjEndAPI(&obj);
     }
@@ -1710,6 +1713,7 @@ storagePoolLookupByTargetPath(virConnectPtr conn,
         }
     }
 
+ cleanup:
     VIR_FREE(cleanpath);
     return pool;
 }
@@ -2808,6 +2812,7 @@ static virStorageDriver storageDriver = {
     .storagePoolLookupByName = storagePoolLookupByName, /* 0.4.0 */
     .storagePoolLookupByUUID = storagePoolLookupByUUID, /* 0.4.0 */
     .storagePoolLookupByVolume = storagePoolLookupByVolume, /* 0.4.0 */
+    .storagePoolLookupByTargetPath = storagePoolLookupByTargetPath, /* 4.1.0 */
     .storagePoolCreateXML = storagePoolCreateXML, /* 0.4.0 */
     .storagePoolDefineXML = storagePoolDefineXML, /* 0.4.0 */
     .storagePoolBuild = storagePoolBuild, /* 0.4.0 */