storage: Split out volume wiping as separate backend function

For non-local storage drivers we can't expect to use the "scrub" tool to
wipe the volume. Split the code into a separate backend function so that
we can add protocol specific code later.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1118710

src/storage/storage_backend.h

@@ -87,6 +87,11 @@ typedef int (*virStorageBackendVolumeUpload)(virConnectPtr conn,
                                              unsigned long long offset,
                                              unsigned long long len,
                                              unsigned int flags);
+typedef int (*virStorageBackendVolumeWipe)(virConnectPtr conn,
+                                           virStoragePoolObjPtr pool,
+                                           virStorageVolDefPtr vol,
+                                           unsigned int algorithm,
+                                           unsigned int flags);
 
 /* File creation/cloning functions used for cloning between backends */
 int virStorageBackendCreateRaw(virConnectPtr conn,
@@ -150,6 +155,7 @@ struct _virStorageBackend {
     virStorageBackendVolumeResize resizeVol;
     virStorageBackendVolumeUpload uploadVol;
     virStorageBackendVolumeDownload downloadVol;
+    virStorageBackendVolumeWipe wipeVol;
 };
 
 virStorageBackendPtr virStorageBackendForType(int type);

src/storage/storage_backend_disk.c

@@ -794,4 +794,5 @@ virStorageBackend virStorageBackendDisk = {
     .buildVolFrom = virStorageBackendDiskBuildVolFrom,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };

src/storage/storage_backend_fs.c

@@ -1301,6 +1301,7 @@ virStorageBackend virStorageBackendDirectory = {
     .resizeVol = virStorageBackendFileSystemVolResize,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };
 
 #if WITH_STORAGE_FS
@@ -1321,6 +1322,7 @@ virStorageBackend virStorageBackendFileSystem = {
     .resizeVol = virStorageBackendFileSystemVolResize,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };
 virStorageBackend virStorageBackendNetFileSystem = {
     .type = VIR_STORAGE_POOL_NETFS,
@@ -1340,6 +1342,7 @@ virStorageBackend virStorageBackendNetFileSystem = {
     .resizeVol = virStorageBackendFileSystemVolResize,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };
 
 

src/storage/storage_backend_iscsi.c

@@ -476,4 +476,5 @@ virStorageBackend virStorageBackendISCSI = {
     .findPoolSources = virStorageBackendISCSIFindPoolSources,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };

src/storage/storage_backend_logical.c

@@ -846,4 +846,5 @@ virStorageBackend virStorageBackendLogical = {
     .deleteVol = virStorageBackendLogicalDeleteVol,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };

src/storage/storage_backend_mpath.c

@@ -289,4 +289,5 @@ virStorageBackend virStorageBackendMpath = {
     .refreshPool = virStorageBackendMpathRefreshPool,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };

src/storage/storage_backend_scsi.c

@@ -730,4 +730,5 @@ virStorageBackend virStorageBackendSCSI = {
     .stopPool = virStorageBackendSCSIStopPool,
     .uploadVol = virStorageBackendVolUploadLocal,
     .downloadVol = virStorageBackendVolDownloadLocal,
+    .wipeVol = virStorageBackendVolWipeLocal,
 };

src/storage/storage_driver.c

@@ -2100,6 +2100,7 @@ storageVolWipePattern(virStorageVolPtr obj,
                       unsigned int algorithm,
                       unsigned int flags)
 {
+    virStorageBackendPtr backend;
     virStoragePoolObjPtr pool = NULL;
     virStorageVolDefPtr vol = NULL;
     int ret = -1;
@@ -2113,7 +2114,7 @@ storageVolWipePattern(virStorageVolPtr obj,
         return -1;
     }
 
-    if (!(vol = virStorageVolDefFromVol(obj, &pool, NULL)))
+    if (!(vol = virStorageVolDefFromVol(obj, &pool, &backend)))
         return -1;
 
 
@@ -2134,10 +2135,13 @@ storageVolWipePattern(virStorageVolPtr obj,
         goto cleanup;
     }
 
-    if (virStorageBackendVolWipeLocal(obj->conn, pool, vol, algorithm, flags) < 0)
+    if (!backend->wipeVol) {
+        virReportError(VIR_ERR_NO_SUPPORT, "%s",
+                       _("storage pool doesn't support volume wiping"));
         goto cleanup;
+    }
 
-    ret = 0;
+    ret = backend->wipeVol(obj->conn, pool, vol, algorithm, flags);
 
  cleanup:
     virStoragePoolObjUnlock(pool);