[PATCH V2 4/4] qemu snapshot: use QMP snapshot-save/delete for internal snapshots

The usage of HMP commands are highly discouraged by qemu. Moreover, current snapshot creation routine does not provide flexibility in choosing target device for VM state snapshot. This patch makes use of QMP commands snapshot-save/delete and by default chooses first writable non-shared qcow2 disk (if present) as target for VM state. Signed-off-by: Nikolai Barybin <nikolai.barybin(a)virtuozzo.com&gt; --- src/qemu/qemu_snapshot.c | 207 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 194 insertions(+), 13 deletions(-) diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c index f5260c4a22..42d9385fd5 100644 --- a/src/qemu/qemu_snapshot.c +++ b/src/qemu/qemu_snapshot.c @@ -308,6 +308,114 @@ qemuSnapshotCreateInactiveExternal(virQEMUDriver *driver, return ret; } +static int +qemuSnapshotActiveInternalGetWrdevListHelper(virDomainObj *vm, + char ***wrdevs) +{ + size_t wrdevCount = 0; + size_t i = 0; + g_auto(GStrv) wrdevsInternal = NULL; + + *wrdevs = NULL; + for (i = 0; i < vm->def->ndisks; i++) { + virDomainDiskDef *disk = vm->def->disks[i]; + if (!disk->src->readonly && disk->src->shared) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("found shared writable disk, VM snapshotting has no sense")); + return -1; + } + + if (!disk->src->readonly && !disk->src->shared && + disk->src->format != VIR_STORAGE_FILE_QCOW2) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("found writable non-qcow2 disk, snapshotting forbidden")); + return -1; + } + + if (!disk->src->readonly && !disk->src->shared && + disk->src->format == VIR_STORAGE_FILE_QCOW2) { + if (wrdevCount == 0) + wrdevsInternal = g_new0(char *, vm->def->ndisks + 2); + + wrdevsInternal[wrdevCount++] = g_strdup(disk->src->nodenameformat); + } + } + + if (wrdevCount > 0 && vm->def->os.loader && vm->def->os.loader->nvram && + vm->def->os.loader->nvram->format == VIR_STORAGE_FILE_QCOW2) + wrdevsInternal[wrdevCount] = g_strdup(vm->def->os.loader->nvram->nodenameformat); + + if (wrdevCount == 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("no writable device found for internal snapshot creation/deletion")); + return -1; + } + + *wrdevs = g_steal_pointer(&wrdevsInternal); + return 0; +} + + +static int +qemuSnapshotCreateActiveInternalDone(virDomainObj *vm) +{ + qemuBlockJobData *job = NULL; + qemuDomainObjPrivate *priv = vm->privateData; + + if (!(job = virHashLookup(priv->blockjobs, g_strdup_printf("snapsave%d", vm->def->id)))) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("failed to lookup blockjob 'snapsave%1$d'"), vm->def->id); + return -1; + } + + qemuBlockJobUpdate(vm, job, VIR_ASYNC_JOB_NONE); + if (job->state == VIR_DOMAIN_BLOCK_JOB_FAILED) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("snapshot-save job failed: %1$s"), NULLSTR(job->errmsg)); + return -1; + } + + return job->state == VIR_DOMAIN_BLOCK_JOB_COMPLETED ? 1 : 0; +} + + +static int +qemuSnapshotCreateActiveInternalStart(virDomainObj *vm, + const char *name) +{ + qemuBlockJobData *job = NULL; + g_auto(GStrv) wrdevs = NULL; + int ret = -1; + int rc = 0; + + if (qemuSnapshotActiveInternalGetWrdevListHelper(vm, &wrdevs) < 0) + return -1; + + if (!(job = qemuBlockJobDiskNew(vm, NULL, QEMU_BLOCKJOB_TYPE_SNAPSHOT_SAVE, + g_strdup_printf("snapsave%d", vm->def->id)))) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("failed to create new blockjob")); + return -1; + } + + qemuBlockJobSyncBegin(job); + if (qemuDomainObjEnterMonitorAsync(vm, VIR_ASYNC_JOB_SNAPSHOT) < 0) { + ret = -1; + goto cleanup; + } + + rc = qemuMonitorSnapshotSave(qemuDomainGetMonitor(vm), job->name, + name, wrdevs[0], wrdevs); + qemuDomainObjExitMonitor(vm); + if (rc == 0) { + qemuBlockJobStarted(job, vm); + ret = 0; + } + + cleanup: + qemuBlockJobStartupFinalize(vm, job); + return ret; +} + /* The domain is expected to be locked and active. */ static int @@ -321,6 +429,7 @@ qemuSnapshotCreateActiveInternal(virQEMUDriver *driver, bool resume = false; virDomainSnapshotDef *snapdef = virDomainSnapshotObjGetDef(snap); int ret = -1; + int rv = 0; if (!qemuMigrationSrcIsAllowed(vm, false, VIR_ASYNC_JOB_SNAPSHOT, 0)) goto cleanup; @@ -342,15 +451,30 @@ qemuSnapshotCreateActiveInternal(virQEMUDriver *driver, } } - if (qemuDomainObjEnterMonitorAsync(vm, VIR_ASYNC_JOB_SNAPSHOT) < 0) { - resume = false; - goto cleanup; - } + if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SNAPSHOT_SAVE)) { + if ((ret = qemuSnapshotCreateActiveInternalStart(vm, snap->def->name)) < 0) { + resume = false; + goto cleanup; + } - ret = qemuMonitorCreateSnapshot(priv->mon, snap->def->name); - qemuDomainObjExitMonitor(vm); - if (ret < 0) - goto cleanup; + while ((rv = qemuSnapshotCreateActiveInternalDone(vm)) != 1) { + if (rv < 0 || qemuDomainObjWait(vm) < 0) { + ret = -1; + goto cleanup; + } + } + /* Legacy support for QEMU versions < 6.0. */ + } else { + if (qemuDomainObjEnterMonitorAsync(vm, VIR_ASYNC_JOB_SNAPSHOT) < 0) { + resume = false; + goto cleanup; + } + + ret = qemuMonitorCreateSnapshot(priv->mon, snap->def->name); + qemuDomainObjExitMonitor(vm); + if (ret < 0) + goto cleanup; + } if (!(snapdef->cookie = (virObject *) qemuDomainSaveCookieNew(vm))) goto cleanup; @@ -3603,6 +3727,54 @@ qemuSnapshotDiscardMetadata(virDomainObj *vm, } +static int +qemuSnapshotDiscardActiveInternal(virDomainObj *vm, + const char *name) +{ + qemuBlockJobData *job = NULL; + g_auto(GStrv) wrdevs = NULL; + int ret = -1; + int rc = 0; + + if (qemuSnapshotActiveInternalGetWrdevListHelper(vm, &wrdevs) < 0) + return -1; + + if (!(job = qemuBlockJobDiskNew(vm, NULL, QEMU_BLOCKJOB_TYPE_SNAPSHOT_DELETE, + g_strdup_printf("snapdelete%d", vm->def->id)))) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("failed to create new blockjob")); + return -1; + } + + qemuBlockJobSyncBegin(job); + if (qemuDomainObjEnterMonitorAsync(vm, VIR_ASYNC_JOB_SNAPSHOT) < 0) + goto cleanup; + + rc = qemuMonitorSnapshotDelete(qemuDomainGetMonitor(vm), job->name, name, wrdevs); + qemuDomainObjExitMonitor(vm); + if (rc == 0) { + qemuBlockJobStarted(job, vm); + ret = 0; + } else { + goto cleanup; + } + + while (job->state != VIR_DOMAIN_BLOCK_JOB_COMPLETED) { + qemuDomainObjWait(vm); + qemuBlockJobUpdate(vm, job, VIR_ASYNC_JOB_NONE); + if (job->state == VIR_DOMAIN_BLOCK_JOB_FAILED) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("snapshot-delete job failed: %1$s"), NULLSTR(job->errmsg)); + ret = -1; + break; + } + } + + cleanup: + qemuBlockJobStartupFinalize(vm, job); + return ret; +} + + /* Discard one snapshot (or its metadata), without reparenting any children. */ static int qemuSnapshotDiscardImpl(virQEMUDriver *driver, @@ -3642,14 +3814,23 @@ qemuSnapshotDiscardImpl(virQEMUDriver *driver, if (qemuSnapshotDiscardExternal(vm, snap, externalData) < 0) return -1; } else { + qemuDomainObjPrivate *priv = vm->privateData; + /* Similarly as internal snapshot creation we would use a regular job * here so set a mask to forbid any other job. */ qemuDomainObjSetAsyncJobMask(vm, VIR_JOB_NONE); - if (qemuDomainObjEnterMonitorAsync(vm, VIR_ASYNC_JOB_SNAPSHOT) < 0) - return -1; - /* we continue on even in the face of error */ - qemuMonitorDeleteSnapshot(qemuDomainGetMonitor(vm), snap->def->name); - qemuDomainObjExitMonitor(vm); + + if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SNAPSHOT_DELETE)) { + qemuSnapshotDiscardActiveInternal(vm, snap->def->name); + /* Legacy support for QEMU versions < 6.0. */ + } else { + if (qemuDomainObjEnterMonitorAsync(vm, VIR_ASYNC_JOB_SNAPSHOT) < 0) + return -1; + /* we continue on even in the face of error */ + qemuMonitorDeleteSnapshot(qemuDomainGetMonitor(vm), snap->def->name); + qemuDomainObjExitMonitor(vm); + } + qemuDomainObjSetAsyncJobMask(vm, VIR_JOB_DEFAULT_MASK); } } -- 2.43.5