Re: [Qemu-devel] [PATCH] Fix COR by disabling BDRV_O_COPY_ON_READ before opening the backing_file.

["Benoît Canet" <benoit.canet@irqsave.net>]

Le Friday 25 Oct 2013 à 02:15:07 (+0200), Thibaut LAURENT a écrit :
> Since commit 0ebd24e0a203cf2852c310b59fbe050190dc6c8c,
> bdrv_open_common will throw an error when trying to open a file
> read-only with the BDRV_O_COPY_ON_READ flag set.
> Although BDRV_O_RDWR is unset for the backing files,
> BDRV_O_COPY_ON_READ is still passed on if copy-on-read was requested
> for the drive. Let's unset this flag too before opening the backing
> file, or bdrv_open_common will fail.
> 
> Signed-off-by: Thibaut LAURENT <thibaut.laurent@gmail.com>
> ---
>  block.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/block.c b/block.c
> index fd05a80..4474012 100644
> --- a/block.c
> +++ b/block.c
> @@ -999,7 +999,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
>      }
>  
>      /* backing files always opened read-only */
> -    back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT);
> +    back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
> +                                    BDRV_O_COPY_ON_READ);
>  
>      ret = bdrv_open(bs->backing_hd,
>                      *backing_filename ? backing_filename : NULL, options,
> -- 
> 1.8.4.1
> 
> 

Reviewed-by: Benoit Canet <benoit@irqsave.net>