Re: [Qemu-devel] [PATCH 3/6] luks: Support .bdrv_co_create

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Mar 09, 2018 at 06:27:10PM +0100, Kevin Wolf wrote:
> This adds the .bdrv_co_create driver callback to luks, which enables
> image creation over QMP.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  qapi/block-core.json | 17 ++++++++++++++++-
>  block/crypto.c       | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 524d51567a..07039bfe9c 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -3452,6 +3452,21 @@
>              '*preallocation':   'PreallocMode' } }
>  
>  ##
> +# @BlockdevCreateOptionsLUKS:
> +#
> +# Driver specific image creation options for LUKS.
> +#
> +# @file             Node to create the image format on
> +# @size             Size of the virtual disk in bytes
> +#
> +# Since: 2.12
> +##
> +{ 'struct': 'BlockdevCreateOptionsLUKS',
> +  'data': { 'file':             'BlockdevRef',
> +            'qcrypto':          'QCryptoBlockCreateOptionsLUKS',
> +            'size':             'size' } }

s/qcrypto/crypto/ in this field.


I do wonder about whether instead of embedding QCryptoBlockCreateOptionsLUKS
as a field, we could instead use QCryptoBlockCreateOptionsLUKS as the
base struct and just inherit from it to add file/size.

I'm not really fussed, but I wonder if you/Eric have any thoughts on the pros
or cons of inheritance vs embedding in this case.

> +
> +##
>  # @BlockdevCreateOptionsNfs:
>  #
>  # Driver specific image creation options for NFS.
> @@ -3643,7 +3658,7 @@
>        'http':           'BlockdevCreateNotSupported',
>        'https':          'BlockdevCreateNotSupported',
>        'iscsi':          'BlockdevCreateNotSupported',
> -      'luks':           'BlockdevCreateNotSupported',
> +      'luks':           'BlockdevCreateOptionsLUKS',
>        'nbd':            'BlockdevCreateNotSupported',
>        'nfs':            'BlockdevCreateOptionsNfs',
>        'null-aio':       'BlockdevCreateNotSupported',
> diff --git a/block/crypto.c b/block/crypto.c
> index b0a4cb3388..2035f9ab13 100644
> --- a/block/crypto.c
> +++ b/block/crypto.c
> @@ -543,6 +543,39 @@ static int block_crypto_open_luks(BlockDriverState *bs,
>                                       bs, options, flags, errp);
>  }
>  
> +static int coroutine_fn
> +block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
> +{
> +    BlockdevCreateOptionsLUKS *luks_opts;
> +    BlockDriverState *bs = NULL;
> +    QCryptoBlockCreateOptions create_opts;
> +    int ret;
> +
> +    assert(create_options->driver == BLOCKDEV_DRIVER_LUKS);
> +    luks_opts = &create_options->u.luks;
> +
> +    bs = bdrv_open_blockdev_ref(luks_opts->file, errp);
> +    if (bs == NULL) {
> +        return -EIO;
> +    }
> +
> +    create_opts = (QCryptoBlockCreateOptions) {
> +        .format = Q_CRYPTO_BLOCK_FORMAT_LUKS,
> +        .u.luks = *luks_opts->qcrypto,
> +    };
> +
> +    ret = block_crypto_co_create_generic(bs, luks_opts->size, &create_opts,
> +                                         errp);
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +
> +    ret = 0;
> +fail:
> +    bdrv_unref(bs);
> +    return ret;
> +}
> +
>  static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
>                                                           QemuOpts *opts,
>                                                           Error **errp)
> @@ -647,6 +680,7 @@ BlockDriver bdrv_crypto_luks = {
>      .bdrv_open          = block_crypto_open_luks,
>      .bdrv_close         = block_crypto_close,
>      .bdrv_child_perm    = bdrv_format_default_perms,
> +    .bdrv_co_create     = block_crypto_co_create_luks,
>      .bdrv_co_create_opts = block_crypto_co_create_opts_luks,
>      .bdrv_truncate      = block_crypto_truncate,
>      .create_opts        = &block_crypto_create_opts_luks,
> -- 
> 2.13.6
> 

Regards,
Daniel
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