[libvirt] [PATCH 3/8] qemu: hotplug: Use new source when preparing/translating for media change

[John Ferlan]

On 9/27/18 11:09 AM, Peter Krempa wrote:
> Some internal helpers use only a virDomainDiskDef to do their job. If we
> want to change source for the disk we need to update it to the new
> source in the disk definition for those to work correctly.
> 
> Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> ---
>  src/qemu/qemu_hotplug.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 86afda636e..3043b3257b 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -730,9 +730,12 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
>                                 bool force)
>  {
>      qemuDomainObjPrivatePtr priv = vm->privateData;
> +    virStorageSourcePtr oldsrc = disk->src;
>      int ret = -1;
>      int rc;
> 
> +    disk->src = newsrc;
> +

Doesn't seem like this would be right especially considering what each
of the following calls passing both @disk and @newsrc do.

>      if (qemuHotplugPrepareDiskAccess(driver, vm, disk, newsrc, false) < 0)
>          goto cleanup;

Passing both @disk and @newsrc here after assigning newsrc into
disk->src would seem to do nothing since it temporarily swaps them for
processing, then returns with them swapped back.

Shortly after this passing both @disk and @newsrc into either
qemuDomainChangeMediaBlockdev or qemuDomainChangeMediaLegacy would seem
to be incorrect especially since each deals with what's in the drive
first which would now be incorrect, wouldn't it?

> 
> @@ -744,7 +747,7 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
>      else
>          rc = qemuDomainChangeMediaLegacy(driver, vm, disk, newsrc, force);
> 
> -    virDomainAuditDisk(vm, disk->src, newsrc, "update", rc >= 0);
> +    virDomainAuditDisk(vm, oldsrc, newsrc, "update", rc >= 0);
> 
>      if (rc < 0) {
>          ignore_value(qemuHotplugPrepareDiskAccess(driver, vm, disk, newsrc, true));

This portion would seemingly be problematic too.

Hard to review the rest...

John

> @@ -755,7 +758,8 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
>      ignore_value(qemuRemoveSharedDisk(driver, disk, vm->def->name));
>      ignore_value(qemuHotplugPrepareDiskAccess(driver, vm, disk, NULL, true));
> 
> -    virStorageSourceFree(disk->src);
> +    virStorageSourceFree(oldsrc);
> +    oldsrc = NULL;
>      VIR_STEAL_PTR(disk->src, newsrc);
> 
>      ignore_value(qemuHotplugRemoveManagedPR(driver, vm, QEMU_ASYNC_JOB_NONE));
> @@ -763,6 +767,9 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
>      ret = 0;
> 
>   cleanup:
> +    if (oldsrc)
> +        disk->src = oldsrc;
> +
>      return ret;
>  }
>