[PATCH v6 2/2] qemu: support to drop disk with 'optional' startupPolicy

[Guannan Ren <gren@xxxxxxxxxx>]

Go through disks of guest, if one disk doesn't exist or its backing
chain is broken, with 'optional' startupPolicy, for CDROM and Floppy
we only discard its source path definition in xml, for disks we drop
it from disk list and free it.
---
 include/libvirt/libvirt.h.in |  1 +
 src/qemu/qemu_domain.c       | 69 ++++++++++++++++++++++++++++++++------------
 2 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index 7bd3559..52ac95d 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -4727,6 +4727,7 @@ typedef void (*virConnectDomainEventBlockJobCallback)(virConnectPtr conn,
  */
 typedef enum {
     VIR_DOMAIN_EVENT_DISK_CHANGE_MISSING_ON_START = 0, /* oldSrcPath is set */
+    VIR_DOMAIN_EVENT_DISK_DROP_MISSING_ON_START = 1,
 
 #ifdef VIR_ENUM_SENTINELS
     VIR_DOMAIN_EVENT_DISK_CHANGE_LAST
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 1ff802c..6794e26 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2027,13 +2027,53 @@ cleanup:
 }
 
 static int
+qemuDomainCheckRemoveOptionalDisk(virQEMUDriverPtr driver,
+                                  virDomainObjPtr vm,
+                                  virDomainDiskDefPtr disk)
+{
+    char uuid[VIR_UUID_STRING_BUFLEN];
+    virDomainEventPtr event = NULL;
+    virDomainDiskDefPtr del_disk = NULL;
+
+    virUUIDFormat(vm->def->uuid, uuid);
+
+    VIR_DEBUG("Dropping disk '%s' on domain '%s' (UUID '%s') "
+              "due to inaccessible source '%s'",
+              disk->dst, vm->def->name, uuid, disk->src);
+
+    if (disk->device == VIR_DOMAIN_DISK_DEVICE_CDROM ||
+        disk->device == VIR_DOMAIN_DISK_DEVICE_FLOPPY) {
+
+        event = virDomainEventDiskChangeNewFromObj(vm, disk->src, NULL,
+                                                   disk->info.alias,
+                                                   VIR_DOMAIN_EVENT_DISK_CHANGE_MISSING_ON_START);
+        VIR_FREE(disk->src);
+    } else {
+        event = virDomainEventDiskChangeNewFromObj(vm, disk->src, NULL,
+                                                   disk->info.alias,
+                                                   VIR_DOMAIN_EVENT_DISK_DROP_MISSING_ON_START);
+
+        if (!(del_disk = virDomainDiskRemoveByName(vm->def, disk->src))) {
+            virReportError(VIR_ERR_INVALID_ARG,
+                           _("no source device %s"), disk->src);
+            return -1;
+        }
+        virDomainDiskDefFree(del_disk);
+    }
+
+    if (event)
+        qemuDomainEventQueue(driver, event);
+
+    return 0;
+}
+
+static int
 qemuDomainCheckDiskStartupPolicy(virQEMUDriverPtr driver,
                                  virDomainObjPtr vm,
                                  virDomainDiskDefPtr disk,
                                  bool cold_boot)
 {
     char uuid[VIR_UUID_STRING_BUFLEN];
-    virDomainEventPtr event = NULL;
     int startupPolicy = disk->startupPolicy;
 
     virUUIDFormat(vm->def->uuid, uuid);
@@ -2056,17 +2096,8 @@ qemuDomainCheckDiskStartupPolicy(virQEMUDriverPtr driver,
             break;
     }
 
-    virResetLastError();
-    VIR_DEBUG("Dropping disk '%s' on domain '%s' (UUID '%s') "
-              "due to inaccessible source '%s'",
-              disk->dst, vm->def->name, uuid, disk->src);
-
-    event = virDomainEventDiskChangeNewFromObj(vm, disk->src, NULL, disk->info.alias,
-                                               VIR_DOMAIN_EVENT_DISK_CHANGE_MISSING_ON_START);
-    if (event)
-        qemuDomainEventQueue(driver, event);
-
-    VIR_FREE(disk->src);
+    if (qemuDomainCheckRemoveOptionalDisk(driver, vm, disk) < 0)
+        goto error;
 
     return 0;
 
@@ -2080,11 +2111,12 @@ qemuDomainCheckDiskPresence(virQEMUDriverPtr driver,
                             bool cold_boot)
 {
     int ret = -1;
-    size_t i;
+    ssize_t i;
     virDomainDiskDefPtr disk;
+    size_t ndisks = vm->def->ndisks;
 
     VIR_DEBUG("Checking for disk presence");
-    for (i = 0; i < vm->def->ndisks; i++) {
+    for (i = ndisks - 1; i >= 0; i--) {
         disk = vm->def->disks[i];
 
         if (!disk->src)
@@ -2094,10 +2126,11 @@ qemuDomainCheckDiskPresence(virQEMUDriverPtr driver,
             qemuDiskChainCheckBroken(disk) >= 0)
             continue;
 
-        if (disk->startupPolicy) {
-            if (qemuDomainCheckDiskStartupPolicy(driver, vm, disk,
-                                                 cold_boot) >= 0)
-                continue;
+        if (disk->startupPolicy &&
+            qemuDomainCheckDiskStartupPolicy(driver, vm, disk,
+                                             cold_boot) >= 0) {
+            virResetLastError();
+            continue;
         }
 
         goto error;
-- 
1.8.3.1

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