[PATCH v2 2/2] qemu: Implement migration optional disk

[Michal Privoznik <mprivozn@xxxxxxxxxx>]

This patch implements previous extension in qemu driver.
That is, during prepare phase check for every source to be accessible.
If not, but marked as optional, simply VIR_FREE the source.
Moreover, if migration is persistent, we must check inactive xml,
which is transfered at the finish phase, as well.
---
 src/qemu/qemu_migration.c |   51 +++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 1122dab..4aa2532 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1039,6 +1039,48 @@ cleanup:
     return rv;
 }
 
+/* qemuCheckDisksPresence:
+ * @def domain definition
+ *
+ * Iterate over domain disks and check if source exists.
+ * If not and:
+ * - it's marked as optional, free() it.
+ * - it's marked as required, throw an error.
+ *
+ * Returns 0 on success (all remaining disks/sources exist
+ * or have been dropped),
+ * -1 on failure.
+ */
+static int
+qemuCheckDisksPresence(virDomainDefPtr def) {
+    int ret = -1;
+    int i;
+    virDomainDiskDefPtr disk;
+
+    for (i = 0; i < def->ndisks; i++) {
+        disk = def->disks[i];
+
+        if (virFileExists(disk->src)) {
+            if (disk->migration.optional == VIR_DOMAIN_DEVICE_MIGRATION_OPT_DROP)
+                VIR_FREE(disk->src);
+
+            continue;
+        }
+
+        if (disk->migration.optional == VIR_DOMAIN_DEVICE_MIGRATION_OPT_REQ) {
+            qemuReportError(VIR_ERR_NO_SOURCE,
+                            _("no such file %s"),
+                            disk->src);
+            goto cleanup;
+        }
+
+        VIR_FREE(disk->src);
+    }
+
+    ret = 0;
+cleanup:
+    return ret;
+}
 
 /* Prepare is the first step, and it runs on the destination host.
  */
@@ -1087,6 +1129,9 @@ qemuMigrationPrepareAny(struct qemud_driver *driver,
     if (virDomainObjIsDuplicate(&driver->domains, def, 1) < 0)
         goto cleanup;
 
+    if (qemuCheckDisksPresence(def) < 0)
+        goto cleanup;
+
     if (!(vm = virDomainAssignDef(driver->caps,
                                   &driver->domains,
                                   def, true))) {
@@ -2579,9 +2624,11 @@ qemuMigrationFinish(struct qemud_driver *driver,
             if (vm->persistent)
                 newVM = 0;
             vm->persistent = 1;
-            if (mig->persistent)
+            if (mig->persistent) {
+                if (qemuCheckDisksPresence(mig->persistent) < 0)
+                    goto endjob;
                 vm->newDef = vmdef = mig->persistent;
-            else
+            } else
                 vmdef = virDomainObjGetPersistentDef(driver->caps, vm);
             if (!vmdef || virDomainSaveConfig(driver->configDir, vmdef) < 0) {
                 /* Hmpf.  Migration was successful, but making it persistent
-- 
1.7.3.4

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