block: Use BDRV_O_NO_BACKING where appropriate

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 <kwolf@redhat.com>
---
 block.c       | 3 ++-
 block/qcow2.c | 3 ++-
 block/vmdk.c  | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

On 2013年11月28日 19:02, Kevin Wolf wrote:
> 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 <kwolf@redhat.com>
> ---
>   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;
>

Reviewed-by: Fam Zheng <famz@redhat.com>

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 <kwolf@redhat.com>
> ---
>  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 <benoit@irqsave.net>

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

Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>