Re: [Qemu-devel] [PATCH 09/10] block/qcow2: implement blockdev-amend

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

On Fri, Aug 30, 2019 at 11:56:07PM +0300, Maxim Levitsky wrote:
> Currently only for changing crypto parameters
> 
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  block/qcow2.c        | 71 ++++++++++++++++++++++++++++++++++++++++++++
>  qapi/block-core.json |  4 +--
>  2 files changed, 73 insertions(+), 2 deletions(-)
> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 8dff4c6b5f..327d2afd9f 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -3082,6 +3082,18 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
>      assert(create_options->driver == BLOCKDEV_DRIVER_QCOW2);
>      qcow2_opts = &create_options->u.qcow2;
>  
> +    if (!qcow2_opts->has_size) {
> +        error_setg(errp, "Size is manadatory for image creation");
> +        return -EINVAL;
> +
> +    }
> +
> +    if (!qcow2_opts->has_file) {
> +        error_setg(errp, "'file' is manadatory for image creation");
> +        return -EINVAL;
> +
> +    }
> +
>      bs = bdrv_open_blockdev_ref(qcow2_opts->file, errp);
>      if (bs == NULL) {
>          return -EIO;
> @@ -5112,6 +5124,64 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
>      return 0;
>  }
>  
> +
> +static int coroutine_fn qcow2_co_amend(BlockDriverState *bs,
> +                                       BlockdevCreateOptions *opts,
> +                                       bool force,
> +                                       Error **errp)
> +{
> +    BlockdevCreateOptionsQcow2 *qopts = &opts->u.qcow2;
> +    BDRVQcow2State *s = bs->opaque;
> +    int ret;
> +
> +    /*
> +     * This is ugly as hell, in later versions of this patch
> +     * something has to be done about this
> +     */
> +    if (qopts->has_file || qopts->has_size || qopts->has_data_file ||
> +        qopts->has_data_file_raw || qopts->has_version ||
> +        qopts->has_backing_file || qopts->has_backing_fmt ||
> +        qopts->has_cluster_size || qopts->has_preallocation ||
> +        qopts->has_lazy_refcounts || qopts->has_refcount_bits) {
> +
> +        error_setg(errp,
> +                "Only LUKS encryption options can be amended for qcow2 with blockdev-amend");
> +        return -EOPNOTSUPP;
> +
> +    }
> +
> +    if (qopts->has_encrypt) {
> +        if (!s->crypto) {
> +            error_setg(errp, "QCOW2 image is not encrypted, can't amend");
> +            return -EOPNOTSUPP;
> +        }
> +
> +        if (qopts->encrypt->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
> +            error_setg(errp,
> +                       "Amend can't be used to change the qcow2 encryption format");
> +            return -EOPNOTSUPP;
> +        }
> +
> +        if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
> +            error_setg(errp,
> +                       "Only LUKS encryption options can be amended for qcow2 with blockdev-amend");
> +            return -EOPNOTSUPP;
> +        }
> +
> +        ret = qcrypto_block_amend_options(s->crypto,
> +                                          qcow2_crypto_hdr_read_func,
> +                                          qcow2_crypto_hdr_write_func,
> +                                          bs,
> +                                          qopts->encrypt,
> +                                          force,
> +                                          errp);
> +        if (ret) {
> +            return ret;
> +        }
> +    }
> +    return 0;
> +}
> +
>  /*
>   * If offset or size are negative, respectively, they will not be included in
>   * the BLOCK_IMAGE_CORRUPTED event emitted.
> @@ -5304,6 +5374,7 @@ BlockDriver bdrv_qcow2 = {
>      .mutable_opts        = mutable_opts,
>      .bdrv_co_check       = qcow2_co_check,
>      .bdrv_amend_options  = qcow2_amend_options,
> +    .bdrv_co_amend       = qcow2_co_amend,
>  
>      .bdrv_detach_aio_context  = qcow2_detach_aio_context,
>      .bdrv_attach_aio_context  = qcow2_attach_aio_context,
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 02375fb59a..ba41744427 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -4312,10 +4312,10 @@
>  # Since: 2.12
>  ##
>  { 'struct': 'BlockdevCreateOptionsQcow2',
> -  'data': { 'file':             'BlockdevRef',
> +  'data': { '*file':            'BlockdevRef',
>              '*data-file':       'BlockdevRef',
>              '*data-file-raw':   'bool',
> -            'size':             'size',
> +            '*size':            'size',
>              '*version':         'BlockdevQcow2Version',
>              '*backing-file':    'str',
>              '*backing-fmt':     'BlockdevDriver',

Docs comment to say they  are mandatory for creation.


Regards,
Daniel
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