Commit 6bff597b authored by Peter Krempa's avatar Peter Krempa Committed by Kevin Wolf
Browse files

block: don't add 'driver' to options when referring to backing via node name 



When referring to a backing file of an image via node name
bdrv_open_backing_file would add the 'driver' option to the option list
filling it with the backing format driver. This breaks construction of
the backing chain via -blockdev, as bdrv_open_inherit reports an error
if both 'reference' and 'options' are provided.

$ qemu-img create -f raw /tmp/backing.raw 64M
$ qemu-img create -f qcow2 -F raw -b /tmp/backing.raw /tmp/test.qcow2
$ qemu-system-x86_64 \
  -blockdev driver=file,filename=/tmp/backing.raw,node-name=backing \
  -blockdev driver=qcow2,file.driver=file,file.filename=/tmp/test.qcow2,node-name=root,backing=backing
qemu-system-x86_64: -blockdev driver=qcow2,file.driver=file,file.filename=/tmp/test.qcow2,node-name=root,backing=backing: Could not open backing file: Cannot reference an existing block device with additional options or a new filename

Signed-off-by: default avatarPeter Krempa <pkrempa@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent ae49fbbc

block.c

+2 −1
Original line number Diff line number Diff line
@@ -2245,7 +2245,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, 
        goto free_exit;

    }



    if (bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {

    if (!reference &&

        bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {

        qdict_put_str(options, "driver", bs->backing_format);

    }