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

[Peter Krempa]

On 05/27/14 16:53, Jiri Denemark wrote:
> 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

s/frontends/backends/ ?

> 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;

Should this be treated the same way for propagating errors as in the
previous patch? I'm not going to enforce this here as the allocaion is
unlikely to fail.

> +
> +    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);

ACK if you go with this patch as-is, v2 if you upgrade the error reporting.

Peter



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