[libvirt] [PATCH] blockcopy: check dst = identical device

[Kashyap Chamarthy]

On Tue, Jul 29, 2014 at 05:59:32PM +0800, Chunyan Liu wrote:
> Check whether dst is the same device as source, if yes, report
> error and exit.

> Currently if dst is the same device as source, blockcopy is still
> going and qemu 'drive-mirror' is executed. 
> Considering that:
> a). blockcopy to the same device is meaningless.

True, I can't think of any useful reason to have dst and src be same
device, except for a negative test case.

> b.) result is
> unexpected. (tested with block device whose source path is /dev/sdaX,
> after blockcopy, shutdown VM and then create VM from xml again, the
> VM cannot be started.) This case should not be allowed.
> 
> Signed-off-by: Chunyan Liu <cyliu at suse.com>
> ---
>  src/qemu/qemu_driver.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 704ba39..87a3790 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -15309,6 +15309,13 @@ qemuDomainBlockCopy(virDomainObjPtr vm,
>      }
>  
>      /* Prepare the destination file.  */
> +    if (STREQ(disk->src->path, dest)) {
> +        virReportError(VIR_ERR_INVALID_ARG,
> +                       _("destination '%s' is the same as disk '%s' source"),
> +                       dest, path);
> +        goto endjob;
> +    }
> +
>      if (stat(dest, &st) < 0) {
>          if (errno != ENOENT) {
>              virReportSystemError(errno, _("unable to stat for disk %s: %s"),
> -- 
> 1.8.4.5
> 
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-- 
/kashyap