[libvirt] [PATCH 4/4] qemu: Use error from Finish instead of "unexpectedly failed"

[Jiri Denemark]

When QEMU exits on destination during migration, the source reports
either success (if the failure happened at the very end) or unhelpful
"unexpectedly failed" error message. However, the Finish API called on
the destination may report a real error so let's use it instead of the
generic one.

Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---
 src/libvirt-domain.c      | 21 +++++++++++++++++++--
 src/qemu/qemu_migration.c | 30 ++++++++++++++++++++++++++++--
 2 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index 909c264..f18fee2 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -3175,8 +3175,25 @@ virDomainMigrateVersion3Full(virDomainPtr domain,
             (dconn, dname, cookiein, cookieinlen, &cookieout, &cookieoutlen,
              NULL, uri, destflags, cancelled);
     }
-    if (cancelled && ddomain)
-        VIR_ERROR(_("finish step ignored that migration was cancelled"));
+
+    if (cancelled) {
+        if (ddomain)
+            VIR_ERROR(_("finish step ignored that migration was cancelled"));
+
+        /* If Finish reported a useful error, use it instead of the original
+         * "migration unexpectedly failed" error.
+         */
+        if (orig_err &&
+            orig_err->domain == VIR_FROM_QEMU &&
+            orig_err->code == VIR_ERR_OPERATION_FAILED) {
+            virErrorPtr err = virGetLastError();
+            if (err->domain == VIR_FROM_QEMU &&
+                err->code != VIR_ERR_MIGRATE_FINISH_OK) {
+                virFreeError(orig_err);
+                orig_err = NULL;
+            }
+        }
+    }
 
     /* If ddomain is NULL, then we were unable to start
      * the guest on the target, and must restart on the
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 3548d73..d02a0c6 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -4957,8 +4957,25 @@ doPeer2PeerMigrate3(virQEMUDriverPtr driver,
              dconnuri, uri, destflags, cancelled);
         qemuDomainObjExitRemote(vm);
     }
-    if (cancelled && ddomain)
-        VIR_ERROR(_("finish step ignored that migration was cancelled"));
+
+    if (cancelled) {
+        if (ddomain)
+            VIR_ERROR(_("finish step ignored that migration was cancelled"));
+
+        /* If Finish reported a useful error, use it instead of the original
+         * "migration unexpectedly failed" error.
+         */
+        if (orig_err &&
+            orig_err->domain == VIR_FROM_QEMU &&
+            orig_err->code == VIR_ERR_OPERATION_FAILED) {
+            virErrorPtr err = virGetLastError();
+            if (err->domain == VIR_FROM_QEMU &&
+                err->code != VIR_ERR_MIGRATE_FINISH_OK) {
+                virFreeError(orig_err);
+                orig_err = NULL;
+            }
+        }
+    }
 
     /* If ddomain is NULL, then we were unable to start
      * the guest on the target, and must restart on the
@@ -5676,6 +5693,15 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
         /* Guest is successfully running, so cancel previous auto destroy */
         qemuProcessAutoDestroyRemove(driver, vm);
     } else if (!(flags & VIR_MIGRATE_OFFLINE)) {
+        qemuDomainJobInfo info;
+
+        /* Check for a possible error on the monitor in case Finish was called
+         * earlier than monitor EOF handler got a chance to process the error
+         */
+        qemuMigrationFetchJobStatus(driver, vm,
+                                    QEMU_ASYNC_JOB_MIGRATION_IN,
+                                    &info);
+
         qemuProcessStop(driver, vm, VIR_DOMAIN_SHUTOFF_FAILED,
                         VIR_QEMU_PROCESS_STOP_MIGRATED);
         virDomainAuditStop(vm, "failed");
-- 
2.4.5