[libvirt] [PATCH 3/4] qemu: Remove disk backend only after frontend is gone

[Jiri Denemark]

In general, we should only remove a backend after seeing DEVICE_DELETED
event for a corresponding frontend. This doesn't make any difference for
disks attached using -drive or drive_add since QEMU automatically
removes their frontends but it's still better to make our code
consistent. And it may start making difference in case we switch to
attaching disks using -blockdev.

Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---
 src/qemu/qemu_hotplug.c | 37 +++++++++++++------------------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index fd1f002..43c52bf 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2472,10 +2472,23 @@ qemuDomainRemoveDiskDevice(virQEMUDriverPtr driver,
     virObjectEventPtr event;
     size_t i;
     const char *src = virDomainDiskGetSource(disk);
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    char *drivestr;
 
     VIR_DEBUG("Removing disk %s from domain %p %s",
               disk->info.alias, vm, vm->def->name);
 
+    /* build the actual drive id string as the disk->info.alias doesn't
+     * contain the QEMU_DRIVE_HOST_PREFIX that is passed to qemu */
+    if (virAsprintf(&drivestr, "%s%s",
+                    QEMU_DRIVE_HOST_PREFIX, disk->info.alias) < 0)
+        return;
+
+    qemuDomainObjEnterMonitor(driver, vm);
+    qemuMonitorDriveDel(priv->mon, drivestr);
+    qemuDomainObjExitMonitor(driver, vm);
+    VIR_FREE(drivestr);
+
     virDomainAuditDisk(vm, src, NULL, "detach", true);
 
     event = virDomainEventDeviceRemovedNewFromObj(vm, disk->info.alias);
@@ -2872,7 +2885,6 @@ qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
 {
     int ret = -1;
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    char *drivestr = NULL;
     int rc;
 
     if (qemuIsMultiFunctionDevice(vm->def, &detach->info)) {
@@ -2899,12 +2911,6 @@ qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
         }
     }
 
-    /* build the actual drive id string as the disk->info.alias doesn't
-     * contain the QEMU_DRIVE_HOST_PREFIX that is passed to qemu */
-    if (virAsprintf(&drivestr, "%s%s",
-                    QEMU_DRIVE_HOST_PREFIX, detach->info.alias) < 0)
-        goto cleanup;
-
     qemuDomainMarkDeviceForRemoval(vm, &detach->info);
 
     qemuDomainObjEnterMonitor(driver, vm);
@@ -2924,10 +2930,6 @@ qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
             goto cleanup;
         }
     }
-
-    /* disconnect guest from host device */
-    qemuMonitorDriveDel(priv->mon, drivestr);
-
     qemuDomainObjExitMonitor(driver, vm);
 
     rc = qemuDomainWaitForDeviceRemoval(vm);
@@ -2937,7 +2939,6 @@ qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
 
  cleanup:
     qemuDomainResetDeviceRemoval(vm);
-    VIR_FREE(drivestr);
     return ret;
 }
 
@@ -2948,7 +2949,6 @@ qemuDomainDetachDiskDevice(virQEMUDriverPtr driver,
 {
     int ret = -1;
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    char *drivestr = NULL;
     int rc;
 
     if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE)) {
@@ -2965,12 +2965,6 @@ qemuDomainDetachDiskDevice(virQEMUDriverPtr driver,
         goto cleanup;
     }
 
-    /* build the actual drive id string as the disk->info.alias doesn't
-     * contain the QEMU_DRIVE_HOST_PREFIX that is passed to qemu */
-    if (virAsprintf(&drivestr, "%s%s",
-                    QEMU_DRIVE_HOST_PREFIX, detach->info.alias) < 0)
-        goto cleanup;
-
     qemuDomainMarkDeviceForRemoval(vm, &detach->info);
 
     qemuDomainObjEnterMonitor(driver, vm);
@@ -2980,10 +2974,6 @@ qemuDomainDetachDiskDevice(virQEMUDriverPtr driver,
                            NULL, "detach", false);
         goto cleanup;
     }
-
-    /* disconnect guest from host device */
-    qemuMonitorDriveDel(priv->mon, drivestr);
-
     qemuDomainObjExitMonitor(driver, vm);
 
     rc = qemuDomainWaitForDeviceRemoval(vm);
@@ -2993,7 +2983,6 @@ qemuDomainDetachDiskDevice(virQEMUDriverPtr driver,
 
  cleanup:
     qemuDomainResetDeviceRemoval(vm);
-    VIR_FREE(drivestr);
     return ret;
 }
 
-- 
1.9.3