libvirt treats 'luks' images as raw+encryption. The logic in
qemuBlockStorageSourceCreateFormat skipped the creation if the requested
image was raw but didn't take into account the encryption.

This manifested itself e.g. when attempting to do a virsh blockcopy with
the following XML:

    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/tmp/enccpy'>
        <encryption format='luks'>
          <secret type='passphrase' uuid='0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f'/>
        </encryption>
      </source>
    </disk>

Where qemu would report the following error:

 unable to execute QEMU command 'blockdev-add': Volume is not in LUKS format

rather than actually formatting the image first.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
 src/qemu/qemu_block.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index eab21bc107..22f03da485 100644
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -2479,7 +2479,8 @@ qemuBlockStorageSourceCreateFormat(virDomainObjPtr vm,
     g_autoptr(virJSONValue) createformatprops = NULL;
     int ret;

-    if (src->format == VIR_STORAGE_FILE_RAW)
+    if (src->format == VIR_STORAGE_FILE_RAW &&
+        !src->encryption)
         return 0;

     if (qemuBlockStorageSourceCreateGetFormatProps(src, backingStore,
-- 
2.24.1

On 1/23/20 11:05 AM, Peter Krempa wrote:
> libvirt treats 'luks' images as raw+encryption. The logic in
> qemuBlockStorageSourceCreateFormat skipped the creation if the requested
> image was raw but didn't take into account the encryption.
> 
> This manifested itself e.g. when attempting to do a virsh blockcopy with
> the following XML:
> 
>      <disk type='file' device='disk'>
>        <driver name='qemu' type='raw'/>
>        <source file='/tmp/enccpy'>
>          <encryption format='luks'>
>            <secret type='passphrase' uuid='0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f'/>
>          </encryption>
>        </source>
>      </disk>
> 
> Where qemu would report the following error:
> 
>   unable to execute QEMU command 'blockdev-add': Volume is not in LUKS format
> 
> rather than actually formatting the image first.
> 
> Signed-off-by: Peter Krempa <pkrempa@redhat.com>
> ---
>   src/qemu/qemu_block.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

(Looks like we're going to encounter lots of blockdev corner cases that 
need little fixups like this...)

> diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
> index eab21bc107..22f03da485 100644
> --- a/src/qemu/qemu_block.c
> +++ b/src/qemu/qemu_block.c
> @@ -2479,7 +2479,8 @@ qemuBlockStorageSourceCreateFormat(virDomainObjPtr vm,
>       g_autoptr(virJSONValue) createformatprops = NULL;
>       int ret;
> 
> -    if (src->format == VIR_STORAGE_FILE_RAW)
> +    if (src->format == VIR_STORAGE_FILE_RAW &&
> +        !src->encryption)
>           return 0;
> 
>       if (qemuBlockStorageSourceCreateGetFormatProps(src, backingStore,
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org