qemu: snapshot: Deactivate block nodes on manually snapshotted disks

If the user wants to manually preserve state of the disk we need, apart
from pausing the machine to quiesce all writes, also deactivate the
block nodes of the device. This ensures that qemu writes out metadata
(e.g. block dirty bitmaps) which are normally stored only in memory,
thus allowing a consistent snapshot including the metadata.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c
index c988de37ca781c8f544adea19f2038be7d06a7d6..5c12dca8920836a00ee9f9ac4911e290c6e814bf 100644 (file)
--- a/src/qemu/qemu_snapshot.c
+++ b/src/qemu/qemu_snapshot.c
@@ -1552,6 +1552,83 @@ qemuSnapshotCreateActiveExternalDisks(virDomainObj *vm,
 }
 
 
+static int
+qemuSnapshotCreateActiveExternalDisksManual(virDomainObj *vm,
+                                            virDomainMomentObj *snap,
+                                            virDomainAsyncJob asyncJob)
+{
+    qemuDomainObjPrivate *priv = vm->privateData;
+    virDomainSnapshotDef *snapdef = virDomainSnapshotObjGetDef(snap);
+    g_autoptr(GPtrArray) nodenames = g_ptr_array_new();
+    int ret = 0;
+    size_t i;
+
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_SET_ACTIVE))
+        return 0;
+
+    for (i = 0; i < snapdef->ndisks; i++) {
+        virDomainDiskDef *domdisk = vm->def->disks[i];
+        qemuDomainDiskPrivate *domdiskPriv = QEMU_DOMAIN_DISK_PRIVATE(domdisk);
+        virStorageSource *n;
+
+        if (snapdef->disks[i].snapshot != VIR_DOMAIN_SNAPSHOT_LOCATION_MANUAL)
+            continue;
+
+        if (domdiskPriv->nodeCopyOnRead)
+            g_ptr_array_add(nodenames, domdiskPriv->nodeCopyOnRead);
+
+        if (domdisk->nthrottlefilters > 0) {
+            size_t j;
+
+            for (j = 0; j < domdisk->nthrottlefilters; j++) {
+                g_ptr_array_add(nodenames, (void *) qemuBlockThrottleFilterGetNodename(domdisk->throttlefilters[j]));
+            }
+        }
+
+        for (n = domdisk->src; virStorageSourceIsBacking(n); n = n->backingStore) {
+            const char *tmp;
+
+            if ((tmp = qemuBlockStorageSourceGetFormatNodename(n)))
+                g_ptr_array_add(nodenames, (void *) tmp);
+
+            if ((tmp = qemuBlockStorageSourceGetSliceNodename(n)))
+                g_ptr_array_add(nodenames, (void *) tmp);
+
+            g_ptr_array_add(nodenames, (void *) qemuBlockStorageSourceGetStorageNodename(n));
+
+            if (n->dataFileStore) {
+                if ((tmp = qemuBlockStorageSourceGetFormatNodename(n->dataFileStore)))
+                    g_ptr_array_add(nodenames, (void *) tmp);
+
+                if ((tmp = qemuBlockStorageSourceGetSliceNodename(n->dataFileStore)))
+                    g_ptr_array_add(nodenames, (void *) tmp);
+
+                g_ptr_array_add(nodenames, (void *) qemuBlockStorageSourceGetStorageNodename(n->dataFileStore));
+            }
+        }
+    }
+
+    if (nodenames->len == 0)
+        return 0;
+
+    if (qemuDomainObjEnterMonitorAsync(vm, asyncJob) < 0)
+        return -1;
+
+    for (i = 0; i < nodenames->len; i++) {
+        const char *nodename = g_ptr_array_index(nodenames, i);
+
+        if (qemuMonitorBlockdevSetActive(priv->mon, nodename, false) < 0) {
+            ret = -1;
+            break;
+        }
+    }
+
+    qemuDomainObjExitMonitor(vm);
+
+    return ret;
+}
+
+
 static int
 qemuSnapshotCreateActiveExternal(virQEMUDriver *driver,
                                  virDomainObj *vm,
@@ -1627,6 +1704,10 @@ qemuSnapshotCreateActiveExternal(virQEMUDriver *driver,
         }
     }
 
+    if (has_manual &&
+        qemuSnapshotCreateActiveExternalDisksManual(vm, snap, VIR_ASYNC_JOB_SNAPSHOT) < 0)
+        goto cleanup;
+
     /* We need to collect reply from 'query-named-block-nodes' prior to the
      * migration step as qemu deactivates bitmaps after migration so the result
      * would be wrong */