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Re: [libvirt] [PATCH v3 2/2] snapshot: Store both config and live XML in the snapshot domain





On 8/14/19 11:47 AM, Maxiwell S. Garcia wrote:
The snapshot-create operation of running guests saves the live
XML and uses it to replace the active and inactive domain in
case of revert. So, the config XML is ignored by the snapshot
process. This commit changes it and adds the config XML in the
snapshot XML as the <inactiveDomain> entry.

In case of offline guest, the behavior remains the same and the
config XML is saved in the snapshot XML as <domain> entry. The
behavior of older snapshots of running guests, that don't have
the new <inactiveDomain>, remains the same too. The revert, in
this case, overrides both active and inactive domain with the
<domain> entry. So, the <inactiveDomain> in the snapshot XML is
not required to snapshot work, but it's useful to preserve the
config XML of running guests.

Signed-off-by: Maxiwell S. Garcia <maxiwell linux ibm com>
---

Reviewed-by: Daniel Henrique Barboza <danielhb413 gmail com>
Tested-by: Daniel Henrique Barboza <danielhb413 gmail com>

 src/conf/moment_conf.c   |  1 +
 src/conf/moment_conf.h   | 11 +++++++++++
 src/conf/snapshot_conf.c | 23 +++++++++++++++++++++--
 src/qemu/qemu_driver.c   | 37 ++++++++++++++++++++++++++++---------
 4 files changed, 61 insertions(+), 11 deletions(-)

diff --git a/src/conf/moment_conf.c b/src/conf/moment_conf.c
index fea13f0f97..f54a44b33e 100644
--- a/src/conf/moment_conf.c
+++ b/src/conf/moment_conf.c
@@ -66,6 +66,7 @@ virDomainMomentDefDispose(void *obj)
     VIR_FREE(def->description);
     VIR_FREE(def->parent_name);
     virDomainDefFree(def->dom);
+    virDomainDefFree(def->inactiveDom);
 }
 
 /* Provide defaults for creation time and moment name after parsing XML */
diff --git a/src/conf/moment_conf.h b/src/conf/moment_conf.h
index 9fdbef2172..70cc47bd70 100644
--- a/src/conf/moment_conf.h
+++ b/src/conf/moment_conf.h
@@ -36,7 +36,18 @@ struct _virDomainMomentDef {
     char *parent_name;
     long long creationTime; /* in seconds */
 
+    /*
+     * Store the active domain definition in case of online
+     * guest and the inactive domain definition in case of
+     * offline guest
+     */
     virDomainDefPtr dom;
+
+    /*
+     * Store the inactive domain definition in case of online
+     * guest and leave NULL in case of offline guest
+     */
+    virDomainDefPtr inactiveDom;
 };
 
 virClassPtr virClassForDomainMomentDef(void);
diff --git a/src/conf/snapshot_conf.c b/src/conf/snapshot_conf.c
index 7996589ad2..36435043ca 100644
--- a/src/conf/snapshot_conf.c
+++ b/src/conf/snapshot_conf.c
@@ -235,6 +235,7 @@ virDomainSnapshotDefParse(xmlXPathContextPtr ctxt,
     virDomainSnapshotDefPtr def = NULL;
     virDomainSnapshotDefPtr ret = NULL;
     xmlNodePtr *nodes = NULL;
+    xmlNodePtr inactiveDomNode = NULL;
     size_t i;
     int n;
     char *creation = NULL, *state = NULL;
@@ -244,6 +245,8 @@ virDomainSnapshotDefParse(xmlXPathContextPtr ctxt,
     char *memoryFile = NULL;
     bool offline = !!(flags & VIR_DOMAIN_SNAPSHOT_PARSE_OFFLINE);
     virSaveCookieCallbacksPtr saveCookie = virDomainXMLOptionGetSaveCookie(xmlopt);
+    int domainflags = VIR_DOMAIN_DEF_PARSE_INACTIVE |
+                      VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE;
 
     if (!(def = virDomainSnapshotDefNew()))
         return NULL;
@@ -293,8 +296,6 @@ virDomainSnapshotDefParse(xmlXPathContextPtr ctxt,
          * clients will have to decide between best effort
          * initialization or outright failure.  */
         if ((tmp = virXPathString("string(./domain/@type)", ctxt))) {
-            int domainflags = VIR_DOMAIN_DEF_PARSE_INACTIVE |
-                              VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE;
             xmlNodePtr domainNode = virXPathNode("./domain", ctxt);
 
             VIR_FREE(tmp);
@@ -311,6 +312,16 @@ virDomainSnapshotDefParse(xmlXPathContextPtr ctxt,
         } else {
             VIR_WARN("parsing older snapshot that lacks domain");
         }
+
+        /* /inactiveDomain entry saves the config XML present in a running
+         * VM. In case of absent, leave parent.inactiveDom NULL and use
+         * parent.dom for config and live XML. */
+        if ((inactiveDomNode = virXPathNode("./inactiveDomain", ctxt))) {
+            def->parent.inactiveDom = virDomainDefParseNode(ctxt->node->doc, inactiveDomNode,
+                                                            caps, xmlopt, NULL, domainflags);
+            if (!def->parent.inactiveDom)
+                goto cleanup;
+        }
     } else if (virDomainXMLOptionRunMomentPostParse(xmlopt, &def->parent) < 0) {
         goto cleanup;
     }
@@ -405,6 +416,7 @@ virDomainSnapshotDefParse(xmlXPathContextPtr ctxt,
     VIR_FREE(nodes);
     VIR_FREE(memorySnapshot);
     VIR_FREE(memoryFile);
+    VIR_FREE(inactiveDomNode);
     virObjectUnref(def);
 
     return ret;
@@ -908,6 +920,13 @@ virDomainSnapshotDefFormatInternal(virBufferPtr buf,
         virBufferAddLit(buf, "</domain>\n");
     }
 
+    if (def->parent.inactiveDom) {
+        int inactivedomainflags = domainflags | VIR_DOMAIN_DEF_FORMAT_INACTIVE_NODE;
+        if (virDomainDefFormatInternal(def->parent.inactiveDom, caps,
+                                       inactivedomainflags, buf, xmlopt) < 0)
+            goto error;
+    }
+
     if (virSaveCookieFormatBuf(buf, def->cookie,
                                virDomainXMLOptionGetSaveCookie(xmlopt)) < 0)
         goto error;
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 48c7b5628b..b3edb40a80 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15911,6 +15911,13 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
                                                         VIR_DOMAIN_DEF_PARSE_SKIP_VALIDATE)))
             goto endjob;
 
+        if (vm->newDef) {
+            def->parent.inactiveDom = virDomainDefCopy(vm->newDef, caps,
+                                                       driver->xmlopt, priv->qemuCaps, true);
+            if (!def->parent.inactiveDom)
+                goto endjob;
+        }
+
         if (flags & VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY) {
             align_location = VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL;
             align_match = false;
@@ -16443,6 +16450,7 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
     qemuDomainObjPrivatePtr priv;
     int rc;
     virDomainDefPtr config = NULL;
+    virDomainDefPtr inactiveConfig = NULL;
     virQEMUDriverConfigPtr cfg = NULL;
     virCapsPtr caps = NULL;
     bool was_stopped = false;
@@ -16544,11 +16552,10 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
          * in the failure cases where we know there was no change?  */
     }
 
-    /* Prepare to copy the snapshot inactive xml as the config of this
-     * domain.
-     *
-     * XXX Should domain snapshots track live xml rather
-     * than inactive xml?  */
+    /* Prepare to copy the snapshot inactive domain as the config XML
+     * and the snapshot domain as the live XML. In case of inactive domain
+     * NULL, both config and live XML will be copied from snapshot domain.
+     */
     if (snap->def->dom) {
         config = virDomainDefCopy(snap->def->dom, caps,
                                   driver->xmlopt, priv->qemuCaps, true);
@@ -16556,6 +16563,15 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
             goto endjob;
     }
 
+    if (snap->def->inactiveDom) {
+        inactiveConfig = virDomainDefCopy(snap->def->inactiveDom, caps,
+                                          driver->xmlopt, priv->qemuCaps, true);
+        if (!inactiveConfig)
+            goto endjob;
+    } else {
+        inactiveConfig = config;
+    }
+
     cookie = (qemuDomainSaveCookiePtr) snapdef->cookie;
 
     switch ((virDomainSnapshotState) snapdef->state) {
@@ -16658,16 +16674,19 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
                 goto endjob;
             }
             if (config) {
-                virDomainObjAssignDef(vm, config, false, NULL);
                 virCPUDefFree(priv->origCPU);
                 VIR_STEAL_PTR(priv->origCPU, origCPU);
             }
+            if (inactiveConfig)
+                virDomainObjAssignDef(vm, inactiveConfig, false, NULL);
         } else {
             /* Transitions 2, 3 */
         load:
             was_stopped = true;
+            if (inactiveConfig)
+                virDomainObjAssignDef(vm, inactiveConfig, false, NULL);
             if (config)
-                virDomainObjAssignDef(vm, config, false, NULL);
+                virDomainObjAssignDef(vm, config, true, NULL);
 
             /* No cookie means libvirt which saved the domain was too old to
              * mess up the CPU definitions.
@@ -16753,8 +16772,8 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
             qemuProcessEndJob(driver, vm);
             goto cleanup;
         }
-        if (config)
-            virDomainObjAssignDef(vm, config, false, NULL);
+        if (inactiveConfig)
+            virDomainObjAssignDef(vm, inactiveConfig, false, NULL);
 
         if (flags & (VIR_DOMAIN_SNAPSHOT_REVERT_RUNNING |
                      VIR_DOMAIN_SNAPSHOT_REVERT_PAUSED)) {


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