Re: [Qemu-devel] [PATCH] block: Use BDRV_O_NO_BACKING where appropriate

[Benoît Canet]

Le Thursday 28 Nov 2013 à 12:02:27 (+0100), Kevin Wolf a écrit :
> If you open an image temporarily just because you want to check its size
> or get it flushed, there's no real reason to open the whole backing file
> chain.
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  block.c       | 3 ++-
>  block/qcow2.c | 3 ++-
>  block/vmdk.c  | 2 +-
>  3 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 03e45fc..e2745a5 100644
> --- a/block.c
> +++ b/block.c
> @@ -1061,7 +1061,8 @@ int bdrv_open(BlockDriverState *bs, const char 
> *filename, QDict *options,
>          /* Get the required size from the image */
>          bs1 = bdrv_new("");
>          QINCREF(options);
> -        ret = bdrv_open(bs1, filename, options, 0, drv, &local_err);
> +        ret = bdrv_open(bs1, filename, options, BDRV_O_NO_BACKING,
> +                        drv, &local_err);
>          if (ret < 0) {
>              bdrv_unref(bs1);
>              goto fail;
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 2fe37ed..8e2b6c7 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1588,7 +1588,8 @@ static int qcow2_create2(const char *filename, int64_t 
> total_size,
>  
>      /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning 
> */
>      ret = bdrv_open(bs, filename, NULL,
> -                    BDRV_O_RDWR | BDRV_O_CACHE_WB, drv, &local_err);
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_BACKING,
> +                    drv, &local_err);
>      if (error_is_set(&local_err)) {
>          error_propagate(errp, local_err);
>          goto out;
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 6555663..5fb6c81 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1690,7 +1690,7 @@ static int vmdk_create(const char *filename, 
> QEMUOptionParameter *options,
>      }
>      if (backing_file) {
>          BlockDriverState *bs = bdrv_new("");
> -        ret = bdrv_open(bs, backing_file, NULL, 0, NULL, errp);
> +        ret = bdrv_open(bs, backing_file, NULL, BDRV_O_NO_BACKING, NULL, 
> errp);
>          if (ret != 0) {
>              bdrv_unref(bs);
>              return ret;
> -- 
> 1.8.1.4
> 
> 

Reviewed-by: Benoit Canet <address@hidden>

No Tested-By as it doesn't apply to kevin/master yet.