[libvirt] [PATCHv5 27/28] qemu: snapshot: Refactor image labelling of new snapshot files

[Peter Krempa]

Now that cgroups/security driver/locking driver support labelling of
individual images and tolerate network storage we don't have to refrain
from passing all image files to it. This allows to remove checking code
as we already make sure that the snapshot function won't be called with
unsupported options.
---
 src/qemu/qemu_driver.c | 62 +++++++++++++++-----------------------------------
 1 file changed, 18 insertions(+), 44 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 6721fc9..6623638 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12819,16 +12819,16 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
     if (virAsprintf(&device, "drive-%s", disk->info.alias) < 0)
         goto cleanup;

-    if (virStorageFileInit(snap->src) < 0)
+    if (!(newDiskSrc = virStorageSourceCopy(snap->src, false)))
         goto cleanup;

-    if (qemuGetDriveSourceString(snap->src, NULL, &source) < 0)
+    if (virStorageSourceInitChainElement(newDiskSrc, disk->src, false) < 0)
         goto cleanup;

-    if (!(newDiskSrc = virStorageSourceCopy(snap->src, false)))
+    if (virStorageFileInit(newDiskSrc) < 0)
         goto cleanup;

-    if (virStorageSourceInitChainElement(newDiskSrc, disk->src, false) < 0)
+    if (qemuGetDriveSourceString(newDiskSrc, NULL, &source) < 0)
         goto cleanup;

     if (persistDisk) {
@@ -12840,55 +12840,29 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
             goto cleanup;
     }

-    switch ((virStorageType)snap->src->type) {
-    case VIR_STORAGE_TYPE_BLOCK:
-    case VIR_STORAGE_TYPE_FILE:
-
-        /* create the stub file and set selinux labels; manipulate disk in
-         * place, in a way that can be reverted on failure. */
-        if (!reuse && snap->src->type != VIR_STORAGE_TYPE_BLOCK) {
+    /* pre-create the image file so that we can label it before handing it to qemu */
+    /* XXX we should switch to storage driver based pre-creation of the image */
+    if (virStorageSourceIsLocalStorage(newDiskSrc)) {
+        if (!reuse && newDiskSrc->type != VIR_STORAGE_TYPE_BLOCK) {
             fd = qemuOpenFile(driver, vm, source, O_WRONLY | O_TRUNC | O_CREAT,
                               &need_unlink, NULL);
             if (fd < 0)
                 goto cleanup;
             VIR_FORCE_CLOSE(fd);
         }
+    }

-        if (qemuDomainPrepareDiskChainElement(driver, vm, snap->src,
-                                              VIR_DISK_CHAIN_READ_WRITE) < 0) {
-            qemuDomainPrepareDiskChainElement(driver, vm, snap->src,
-                                              VIR_DISK_CHAIN_NO_ACCESS);
-            goto cleanup;
-        }
-        break;
-
-    case VIR_STORAGE_TYPE_NETWORK:
-        switch (snap->src->protocol) {
-        case VIR_STORAGE_NET_PROTOCOL_GLUSTER:
-            break;
-
-        default:
-            virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
-                           _("snapshots on volumes using '%s' protocol "
-                             "are not supported"),
-                           virStorageNetProtocolTypeToString(snap->src->protocol));
-            goto cleanup;
-        }
-        break;
-
-    case VIR_STORAGE_TYPE_DIR:
-    case VIR_STORAGE_TYPE_VOLUME:
-    case VIR_STORAGE_TYPE_NONE:
-    case VIR_STORAGE_TYPE_LAST:
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
-                       _("snapshots are not supported on '%s' volumes"),
-                       virStorageTypeToString(snap->src->type));
+    /* set correct security, cgroup and locking options on the new image */
+    if (qemuDomainPrepareDiskChainElement(driver, vm, newDiskSrc,
+                                          VIR_DISK_CHAIN_READ_WRITE) < 0) {
+        qemuDomainPrepareDiskChainElement(driver, vm, newDiskSrc,
+                                          VIR_DISK_CHAIN_NO_ACCESS);
         goto cleanup;
     }

     /* create the actual snapshot */
-    if (snap->src->format)
-        formatStr = virStorageFileFormatTypeToString(snap->src->format);
+    if (newDiskSrc->format)
+        formatStr = virStorageFileFormatTypeToString(newDiskSrc->format);

     /* The monitor is only accessed if qemu doesn't support transactions.
      * Otherwise the following monitor command only constructs the command.
@@ -12926,9 +12900,9 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
     }

  cleanup:
-    if (need_unlink && virStorageFileUnlink(snap->src))
+    if (need_unlink && virStorageFileUnlink(newDiskSrc))
         VIR_WARN("unable to unlink just-created %s", source);
-    virStorageFileDeinit(snap->src);
+    virStorageFileDeinit(newDiskSrc);
     virStorageSourceFree(newDiskSrc);
     virStorageSourceFree(persistDiskSrc);
     VIR_FREE(device);
-- 
1.9.3