[libvirt] [PATCH 12/13] backup: Wire up qemu checkpoint commands over QMP

Eric Blake eblake at redhat.com
Wed Jun 19 03:47:53 UTC 2019


Time to actually issue the QMP transactions that create and
delete persistent checkpoints.  For create, we only need one
transaction: inside, we visit all disks affected by the
checkpoint, and create a new enabled bitmap, as well as
disabling the bitmap of the parent checkpoint (if any).  For
deletion, we need multiple calls: if the checkpoint to be
deleted is active, we must enable the parent; then we must
merge the existing checkpoint into the parent, and finally
we can delete the checkpoint.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/qemu/qemu_domain.c | 105 ++++++++++++++++++++++++++++++-----------
 src/qemu/qemu_driver.c |  92 ++++++++++++++++++++++++++++++++++--
 2 files changed, 165 insertions(+), 32 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index e128dc169b..1364227e42 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -8809,45 +8809,93 @@ qemuDomainCheckpointDiscard(virQEMUDriverPtr driver,
     char *chkFile = NULL;
     int ret = -1;
     virDomainMomentObjPtr parentchk = NULL;
+    virDomainCheckpointDefPtr parentdef = NULL;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    size_t i, j;
+    virJSONValuePtr arr = NULL;

-    if (!metadata_only) {
-        if (!virDomainObjIsActive(vm)) {
-            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                           _("cannot remove checkpoint from inactive domain"));
-            goto cleanup;
-        } else {
-            /* TODO: Implement QMP sequence to merge bitmaps */
-            // qemuDomainObjPrivatePtr priv;
-            // priv = vm->privateData;
-            // qemuDomainObjEnterMonitor(driver, vm);
-            // /* we continue on even in the face of error */
-            // qemuMonitorDeleteCheckpoint(priv->mon, chk->def->name);
-            // ignore_value(qemuDomainObjExitMonitor(driver, vm));
-        }
+    if (!metadata_only && !virDomainObjIsActive(vm)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("cannot remove checkpoint from inactive domain"));
+        goto cleanup;
     }

     if (virAsprintf(&chkFile, "%s/%s/%s.xml", cfg->checkpointDir,
                     vm->def->name, chk->def->name) < 0)
         goto cleanup;

+    if (chk->def->parent_name) {
+        parentchk = virDomainCheckpointFindByName(vm->checkpoints,
+                                                  chk->def->parent_name);
+        if (!parentchk) {
+            VIR_WARN("missing parent checkpoint matching name '%s'",
+                     chk->def->parent_name);
+        }
+        parentdef = virDomainCheckpointObjGetDef(parentchk);
+    }
+
+    if (!metadata_only) {
+        qemuDomainObjPrivatePtr priv = vm->privateData;
+        bool success = true;
+        virDomainCheckpointDefPtr chkdef = virDomainCheckpointObjGetDef(chk);
+
+        if (qemuBlockNodeNamesDetect(driver, vm, QEMU_ASYNC_JOB_NONE) < 0)
+            goto cleanup;
+        qemuDomainObjEnterMonitor(driver, vm);
+        for (i = 0; i < chkdef->ndisks; i++) {
+            virDomainCheckpointDiskDef *disk = &chkdef->disks[i];
+            const char *node;
+
+            if (disk->type != VIR_DOMAIN_CHECKPOINT_TYPE_BITMAP)
+                continue;
+
+            node = qemuBlockNodeLookup(vm, disk->name);
+            if (parentchk) {
+                arr = virJSONValueNewArray();
+                if (!arr ||
+                    virJSONValueArrayAppendString(arr, disk->bitmap) < 0) {
+                    success = false;
+                    break;
+                }
+
+                for (j = 0; j < parentdef->ndisks; j++) {
+                    virDomainCheckpointDiskDef *disk2;
+
+                    disk2 = &parentdef->disks[j];
+                    if (STRNEQ(disk->name, disk2->name))
+                        continue;
+                    if (chk == virDomainCheckpointGetCurrent(vm->checkpoints) &&
+                        qemuMonitorEnableBitmap(priv->mon, node,
+                                                disk2->bitmap) < 0) {
+                        success = false;
+                        break;
+                    }
+                    if (qemuMonitorMergeBitmaps(priv->mon, node,
+                                                disk2->bitmap, &arr) < 0) {
+                        success = false;
+                        break;
+                    }
+                }
+            }
+            if (qemuMonitorDeleteBitmap(priv->mon, node, disk->bitmap) < 0) {
+                success = false;
+                break;
+            }
+        }
+        if (qemuDomainObjExitMonitor(driver, vm) < 0 || !success)
+            goto cleanup;
+    }
+
     if (chk == virDomainCheckpointGetCurrent(vm->checkpoints)) {
         virDomainCheckpointSetCurrent(vm->checkpoints, NULL);
-        if (update_parent && chk->def->parent_name) {
-            parentchk = virDomainCheckpointFindByName(vm->checkpoints,
-                                                      chk->def->parent_name);
-            if (!parentchk) {
-                VIR_WARN("missing parent checkpoint matching name '%s'",
+        if (update_parent && parentchk) {
+            virDomainCheckpointSetCurrent(vm->checkpoints, parentchk);
+            if (qemuDomainCheckpointWriteMetadata(vm, parentchk, driver->caps,
+                                                  driver->xmlopt,
+                                                  cfg->checkpointDir) < 0) {
+                VIR_WARN("failed to set parent checkpoint '%s' as current",
                          chk->def->parent_name);
-            } else {
-                virDomainCheckpointSetCurrent(vm->checkpoints, parentchk);
-                if (qemuDomainCheckpointWriteMetadata(vm, parentchk, driver->caps,
-                                                      driver->xmlopt,
-                                                      cfg->checkpointDir) < 0) {
-                    VIR_WARN("failed to set parent checkpoint '%s' as current",
-                             chk->def->parent_name);
-                    virDomainCheckpointSetCurrent(vm->checkpoints, NULL);
-                }
+                virDomainCheckpointSetCurrent(vm->checkpoints, NULL);
             }
         }
     }
@@ -8863,6 +8911,7 @@ qemuDomainCheckpointDiscard(virQEMUDriverPtr driver,
  cleanup:
     VIR_FREE(chkFile);
     virObjectUnref(cfg);
+    virJSONValueFree(arr);
     return ret;
 }

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 5fa319b656..0cdb2dd1e2 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -48,6 +48,7 @@
 #include "qemu_hostdev.h"
 #include "qemu_hotplug.h"
 #include "qemu_monitor.h"
+#include "qemu_monitor_json.h"
 #include "qemu_process.h"
 #include "qemu_migration.h"
 #include "qemu_migration_params.h"
@@ -17016,6 +17017,53 @@ qemuDomainCheckpointPrepare(virQEMUDriverPtr driver, virCapsPtr caps,
     return ret;
 }

+static int
+qemuDomainCheckpointAddActions(virDomainObjPtr vm,
+                               virJSONValuePtr actions,
+                               virDomainMomentObjPtr old_current,
+                               virDomainCheckpointDefPtr def)
+{
+    size_t i, j;
+    int ret = -1;
+    virDomainCheckpointDefPtr olddef;
+
+    olddef = virDomainCheckpointObjGetDef(old_current);
+    for (i = 0; i < def->ndisks; i++) {
+        virDomainCheckpointDiskDef *disk = &def->disks[i];
+        const char *node;
+
+        if (disk->type != VIR_DOMAIN_CHECKPOINT_TYPE_BITMAP)
+            continue;
+        node = qemuBlockNodeLookup(vm, disk->name);
+        if (qemuMonitorJSONTransactionAdd(actions,
+                                          "block-dirty-bitmap-add",
+                                          "s:node", node,
+                                          "s:name", disk->bitmap,
+                                          "b:persistent", true,
+                                          NULL) < 0)
+            goto cleanup;
+        if (old_current) {
+            for (j = 0; j < olddef->ndisks; j++) {
+                virDomainCheckpointDiskDef *disk2;
+
+                disk2 = &olddef->disks[j];
+                if (STRNEQ(disk->name, disk2->name))
+                    continue;
+                if (disk2->type == VIR_DOMAIN_CHECKPOINT_TYPE_BITMAP &&
+                    qemuMonitorJSONTransactionAdd(actions,
+                                                  "block-dirty-bitmap-disable",
+                                                  "s:node", node,
+                                                  "s:name", disk2->bitmap,
+                                                  NULL) < 0)
+                    goto cleanup;
+            }
+        }
+    }
+    ret = 0;
+
+ cleanup:
+    return ret;
+}

 static virDomainCheckpointPtr
 qemuDomainCheckpointCreateXML(virDomainPtr domain,
@@ -17034,6 +17082,9 @@ qemuDomainCheckpointCreateXML(virDomainPtr domain,
     virDomainMomentObjPtr other = NULL;
     virQEMUDriverConfigPtr cfg = NULL;
     virCapsPtr caps = NULL;
+    qemuDomainObjPrivatePtr priv;
+    virJSONValuePtr actions = NULL;
+    int ret;
     VIR_AUTOUNREF(virDomainCheckpointDefPtr) def = NULL;

     virCheckFlags(VIR_DOMAIN_CHECKPOINT_CREATE_REDEFINE |
@@ -17050,11 +17101,18 @@ qemuDomainCheckpointCreateXML(virDomainPtr domain,
     if (!(vm = qemuDomObjFromDomain(domain)))
         goto cleanup;

+    priv = vm->privateData;
     cfg = virQEMUDriverGetConfig(driver);

     if (virDomainCheckpointCreateXMLEnsureACL(domain->conn, vm->def, flags) < 0)
         goto cleanup;

+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BITMAP_MERGE)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("qemu binary lacks persistent bitmaps support"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;

@@ -17094,10 +17152,10 @@ qemuDomainCheckpointCreateXML(virDomainPtr domain,
         def = NULL;
     }

-    current = virDomainCheckpointGetCurrent(vm->checkpoints);
-    if (current) {
+    other = virDomainCheckpointGetCurrent(vm->checkpoints);
+    if (other) {
         if (!redefine &&
-            VIR_STRDUP(chk->def->parent_name, current->def->name) < 0)
+            VIR_STRDUP(chk->def->parent_name, other->def->name) < 0)
             goto endjob;
         if (update_current) {
             virDomainCheckpointSetCurrent(vm->checkpoints, NULL);
@@ -17114,7 +17172,15 @@ qemuDomainCheckpointCreateXML(virDomainPtr domain,
          * makes sense, such as checking that qemu-img recognizes the
          * checkpoint bitmap name in at least one of the domain's disks?  */
     } else {
-        /* TODO: issue QMP transaction command */
+        if (!(actions = virJSONValueNewArray()))
+            goto endjob;
+        if (qemuDomainCheckpointAddActions(vm, actions, other,
+                                           virDomainCheckpointObjGetDef(chk)) < 0)
+            goto endjob;
+        qemuDomainObjEnterMonitor(driver, vm);
+        ret = qemuMonitorTransaction(priv->mon, &actions);
+        if (qemuDomainObjExitMonitor(driver, vm) < 0 || ret < 0)
+            goto endjob;
     }

     /* If we fail after this point, there's not a whole lot we can do;
@@ -17150,6 +17216,7 @@ qemuDomainCheckpointCreateXML(virDomainPtr domain,
     qemuDomainObjEndJob(driver, vm);

  cleanup:
+    virJSONValueFree(actions);
     virDomainObjEndAPI(&vm);
     VIR_FREE(xml);
     virObjectUnref(caps);
@@ -17377,6 +17444,7 @@ qemuDomainCheckpointDelete(virDomainCheckpointPtr checkpoint,
 {
     virQEMUDriverPtr driver = checkpoint->domain->conn->privateData;
     virDomainObjPtr vm = NULL;
+    qemuDomainObjPrivatePtr priv;
     int ret = -1;
     virDomainMomentObjPtr chk = NULL;
     virQEMUMomentRemove rem;
@@ -17399,6 +17467,22 @@ qemuDomainCheckpointDelete(virDomainCheckpointPtr checkpoint,
     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;

+    priv = vm->privateData;
+    if (!metadata_only) {
+        /* Until qemu-img supports offline bitmap deletion, we are stuck
+         * with requiring a running guest */
+        if (!virDomainObjIsActive(vm)) {
+            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                           _("cannot delete checkpoint for inactive domain"));
+            goto endjob;
+        }
+        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BITMAP_MERGE)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("qemu binary lacks persistent bitmaps support"));
+            goto endjob;
+        }
+    }
+
     if (!(chk = qemuCheckObjFromCheckpoint(vm, checkpoint)))
         goto endjob;

-- 
2.20.1




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