[libvirt] [PATCH v7 22/23] backup: qemu: Wire up qemu full push backup commands over QMP

Eric Blake eblake at redhat.com
Wed Mar 27 10:10:53 UTC 2019


Update the code to support push backups; for now, the destination file
still has to be local, although the XML could be extended into
supporting remote destinations (where we will have to use the full
power of blockdev-add). This also touches up the event handling to
inform the user when the job is complete. (However, there are probably
bugs lurking in the event code; pull mode is more tested than push
mode at the time I write this).

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/qemu/qemu_driver.c | 81 +++++++++++++++++++++++++++++-------------
 1 file changed, 56 insertions(+), 25 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e6e7ba7330..9c2bc8175a 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -17758,14 +17758,13 @@ qemuDomainBackupPrepare(virQEMUDriverPtr driver, virDomainObjPtr vm,
 /* Called while monitor lock is held. Best-effort cleanup. */
 static int
 qemuDomainBackupDiskCleanup(virQEMUDriverPtr driver, virDomainObjPtr vm,
-                            virDomainBackupDiskDef *disk, bool incremental)
+                            virDomainBackupDiskDef *disk, bool push,
+                            bool incremental, bool completed)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
     const char *node = vm->def->disks[disk->idx]->src->nodeformat;
     int ret = 0;

-    if (!disk->store)
-        return 0;
     if (disk->state >= VIR_DOMAIN_BACKUP_DISK_STATE_EXPORT) {
         /* No real need to use nbd-server-remove, since we will
          * shortly be calling nbd-server-stop. */
@@ -17778,16 +17777,17 @@ qemuDomainBackupDiskCleanup(virQEMUDriverPtr driver, virDomainObjPtr vm,
     }
     if (disk->state >= VIR_DOMAIN_BACKUP_DISK_STATE_READY &&
         qemuMonitorBlockdevDel(priv->mon, disk->store->nodeformat) < 0) {
-        VIR_WARN("Unable to remove temp disk %s after backup",
-                 disk->name);
+        VIR_WARN("Unable to remove %s disk %s after backup",
+                 push ? "target" : "scratch", disk->name);
         ret = -1;
     }
     if (disk->state >= VIR_DOMAIN_BACKUP_DISK_STATE_LABEL)
         qemuDomainDiskChainElementRevoke(driver, vm, disk->store);
-    if (disk->state >= VIR_DOMAIN_BACKUP_DISK_STATE_CREATED &&
+    if ((!push || !completed) &&
+        disk->state >= VIR_DOMAIN_BACKUP_DISK_STATE_CREATED &&
         disk->store->detected && unlink(disk->store->path) < 0) {
-        VIR_WARN("Unable to unlink temp disk %s after backup",
-                 disk->store->path);
+        VIR_WARN("Unable to unlink %s disk %s after backup",
+                 push ? "failed target" : "scratch", disk->store->path);
         ret = -1;
     }
     return ret;
@@ -17807,6 +17807,7 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
     virJSONValuePtr json = NULL;
     bool job_started = false;
     bool nbd_running = false;
+    bool push;
     size_t i;
     struct timeval tv;
     char *suffix = NULL;
@@ -17855,7 +17856,8 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
     if (!(def = virDomainBackupDefParseString(diskXml, driver->xmlopt, 0)))
         goto cleanup;

-    if (def->type == VIR_DOMAIN_BACKUP_TYPE_PULL) {
+    push = def->type == VIR_DOMAIN_BACKUP_TYPE_PUSH;
+    if (!push) {
         if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_NBD_BITMAP)) {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                            _("qemu binary lacks pull-mode backup support"));
@@ -17867,10 +17869,6 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
                            _("<domainbackup> must specify TCP server for now"));
             goto cleanup;
         }
-    } else {
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("push mode backups not supported yet"));
-        goto cleanup;
     }
     if (def->incremental) {
         if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BITMAP_MERGE)) {
@@ -17951,6 +17949,7 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
             cmd = NULL;
         }

+        /* FIXME: allow non-local files for push destinations */
         if (virJSONValueObjectCreate(&file,
                                      "s:driver", "file",
                                      "s:filename", disk->store->path,
@@ -17991,7 +17990,7 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
                                           "blockdev-backup",
                                           "s:device", src->nodeformat,
                                           "s:target", disk->store->nodeformat,
-                                          "s:sync", "none",
+                                          "s:sync", push ? "full" : "none",
                                           "s:job-id", disk->name,
                                           NULL) < 0)
             goto endmon;
@@ -18004,7 +18003,7 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
        - pull: nbd-server-start with <server> from user (or autogenerate server)
        - pull: nbd-server-add per <disk>, including bitmap for incr
     */
-    if (def->type == VIR_DOMAIN_BACKUP_TYPE_PULL) {
+    if (!push) {
         if (qemuMonitorNBDServerStart(priv->mon, def->server->name,
                                       def->server->port, NULL) < 0)
             goto endmon;
@@ -18036,11 +18035,14 @@ qemuDomainBackupBegin(virDomainPtr domain, const char *diskXml,
         for (i = 0; i < def->ndisks; i++) {
             virDomainBackupDiskDef *disk = &def->disks[i];

+            if (!disk->store)
+                continue;
             if (job_started &&
                 qemuMonitorBlockJobCancel(priv->mon, disk->name) < 0)
                 VIR_WARN("Unable to stop backup job %s on vm %s after failure",
                          disk->store->nodeformat, vm->def->name);
-            qemuDomainBackupDiskCleanup(driver, vm, disk, !!def->incremental);
+            qemuDomainBackupDiskCleanup(driver, vm, disk, push,
+                                        !!def->incremental, false);
         }
         virSetError(save_err);
         virFreeError(save_err);
@@ -18115,6 +18117,8 @@ static int qemuDomainBackupEnd(virDomainPtr domain, int id, unsigned int flags)
     bool want_abort = flags & VIR_DOMAIN_BACKUP_END_ABORT;
     virDomainBackupDefPtr def;
     size_t i;
+    bool push = true;
+    bool completed = true;

     virCheckFlags(VIR_DOMAIN_BACKUP_END_ABORT, -1);

@@ -18133,23 +18137,50 @@ static int qemuDomainBackupEnd(virDomainPtr domain, int id, unsigned int flags)
         goto cleanup;
     }

-    if (priv->backup->type != VIR_DOMAIN_BACKUP_TYPE_PUSH)
-        want_abort = false;
     def = priv->backup;
+    if (def->type != VIR_DOMAIN_BACKUP_TYPE_PUSH) {
+        want_abort = false;
+        push = false;
+    }

     /* We are going to modify the domain below. */
     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;

     qemuDomainObjEnterMonitor(driver, vm);
-    if (def->type == VIR_DOMAIN_BACKUP_TYPE_PULL)
+    if (push) {
+        for (i = 0; i < def->ndisks; i++) {
+            virDomainBackupDiskDef *disk = &def->disks[i];
+
+            if (!disk->store)
+                continue;
+            if (disk->state != VIR_DOMAIN_BACKUP_DISK_STATE_COMPLETE)
+                completed = false;
+        }
+    } else {
         ret = qemuMonitorNBDServerStop(priv->mon);
-    for (i = 0; i < def->ndisks; i++) {
-        if (qemuMonitorBlockJobCancel(priv->mon,
-                                      def->disks[i].name) < 0 ||
-            qemuDomainBackupDiskCleanup(driver, vm, &def->disks[i],
-                                        !!def->incremental) < 0)
-            ret = -1;
+    }
+    if (!completed && !want_abort) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       _("backup job id '%d' not complete yet"), id);
+    } else {
+        for (i = 0; i < def->ndisks; i++) {
+            virDomainBackupDiskDef *disk = &def->disks[i];
+
+            if (!disk->store)
+                continue;
+            if (!push || disk->state < VIR_DOMAIN_BACKUP_DISK_STATE_COMPLETE) {
+                if (qemuMonitorBlockJobCancel(priv->mon,
+                                              disk->name) < 0 &&
+                    !want_abort) {
+                    ret = -1;
+                    continue;
+                }
+            }
+            if (qemuDomainBackupDiskCleanup(driver, vm, disk, push,
+                                            !!def->incremental, completed) < 0)
+                ret = -1;
+        }
     }
     if (qemuDomainObjExitMonitor(driver, vm) < 0 || ret < 0) {
         ret = -1;
-- 
2.20.1




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