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Date: Wed, 27 Nov 2013 10:35:48 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH v2 2/6] block: add
	BlockDriver.bdrv_preallocate.
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To: Hu Tao <hutao@cn.fujitsu.com>, Kevin Wolf <kwolf@redhat.com>, "Daniel P. Berrange" <berrange@redhat.com>, Peter Lieven <pl@kamp.de>
Cc: qemu-devel@nongnu.org

On 2013=E5=B9=B411=E6=9C=8827=E6=97=A5 10:15, Hu Tao wrote:
> This field is used to preallocate disk space for block
> device.
>
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>   block.c                   | 13 +++++++++++++
>   include/block/block.h     |  1 +
>   include/block/block_int.h |  3 +++
>   3 files changed, 17 insertions(+)
>
> diff --git a/block.c b/block.c
> index 382ea71..3985133 100644
> --- a/block.c
> +++ b/block.c
> @@ -3102,6 +3102,19 @@ int bdrv_has_zero_init(BlockDriverState *bs)
>       return 0;
>   }
>
> +int bdrv_preallocate(BlockDriverState *bs, int64_t offset, int64_t len=
gth)
> +{
> +    if (bs->backing_hd) {
> +        return -1;

Better to use -ENOTSUP.

> +    }
> +
> +    if (bs->drv->bdrv_preallocate) {
> +        return bs->drv->bdrv_preallocate(bs, offset, length);
> +    }
> +
> +    return -1;

-ENOTSUP

Fam

> +}
> +
>   typedef struct BdrvCoGetBlockStatusData {
>       BlockDriverState *bs;
>       BlockDriverState *base;
> diff --git a/include/block/block.h b/include/block/block.h
> index 461eaa4..8d48c8a 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -315,6 +315,7 @@ void bdrv_drain_all(void);
>   int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sec=
tors);
>   int bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_=
sectors);
>   int bdrv_has_zero_init_1(BlockDriverState *bs);
> +int bdrv_preallocate(BlockDriverState *bs, int64_t offset, int64_t len=
gth);
>   int bdrv_has_zero_init(BlockDriverState *bs);
>   int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_nu=
m,
>                                 int nb_sectors, int *pnum);
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 1666066..6ac3735 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -227,6 +227,9 @@ struct BlockDriver {
>        */
>       int (*bdrv_has_zero_init)(BlockDriverState *bs);
>
> +    int (*bdrv_preallocate)(BlockDriverState *bs, int64_t offset,
> +                            int64_t length);
> +
>       QLIST_ENTRY(BlockDriver) list;
>   };
>
>