Re: [Qemu-devel] [Qemu-block] [PATCH v3] LUKS: support preallocation

[Stefano Garzarella <sgarzare@redhat.com>]

On Thu, Jul 11, 2019 at 06:09:40PM +0300, Maxim Levitsky wrote:
> preallocation=off and preallocation=metadata
> both allocate luks header only, and preallocation=falloc/full
> is passed to underlying file.
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1534951
> 
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> 
> ---
> 
> Note that QMP support was only compile tested, since I am still learning
> on how to use it.
> 
> If there is some library/script/etc which makes it more high level,
> I would more that glad to hear about it. So far I used the qmp-shell
> 
> Also can I use qmp's blockdev-create outside a vm running?
> 
>  block/crypto.c       | 29 ++++++++++++++++++++++++++---
>  qapi/block-core.json |  5 ++++-
>  2 files changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/block/crypto.c b/block/crypto.c
> index 8237424ae6..034a645652 100644
> --- a/block/crypto.c
> +++ b/block/crypto.c
> @@ -74,6 +74,7 @@ static ssize_t block_crypto_read_func(QCryptoBlock *block,
>  struct BlockCryptoCreateData {
>      BlockBackend *blk;
>      uint64_t size;
> +    PreallocMode prealloc;
>  };
>  
>  
> @@ -112,7 +113,7 @@ static ssize_t block_crypto_init_func(QCryptoBlock *block,
>       * available to the guest, so we must take account of that
>       * which will be used by the crypto header
>       */
> -    return blk_truncate(data->blk, data->size + headerlen, PREALLOC_MODE_OFF,
> +    return blk_truncate(data->blk, data->size + headerlen, data->prealloc,
>                          errp);
>  }
>  
> @@ -251,6 +252,7 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
>  static int block_crypto_co_create_generic(BlockDriverState *bs,
>                                            int64_t size,
>                                            QCryptoBlockCreateOptions *opts,
> +                                          PreallocMode prealloc,
>                                            Error **errp)
>  {
>      int ret;
> @@ -266,9 +268,14 @@ static int block_crypto_co_create_generic(BlockDriverState *bs,
>          goto cleanup;
>      }
>  
> +    if (prealloc == PREALLOC_MODE_METADATA) {
> +        prealloc = PREALLOC_MODE_OFF;
> +    }
> +
>      data = (struct BlockCryptoCreateData) {
>          .blk = blk,
>          .size = size,
> +        .prealloc = prealloc,
>      };
>  
>      crypto = qcrypto_block_create(opts, NULL,
> @@ -500,6 +507,7 @@ block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
>      BlockdevCreateOptionsLUKS *luks_opts;
>      BlockDriverState *bs = NULL;
>      QCryptoBlockCreateOptions create_opts;
> +    PreallocMode preallocation = PREALLOC_MODE_OFF;
>      int ret;
>  
>      assert(create_options->driver == BLOCKDEV_DRIVER_LUKS);
> @@ -515,8 +523,11 @@ block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
>          .u.luks = *qapi_BlockdevCreateOptionsLUKS_base(luks_opts),
>      };
>  
> +    if (luks_opts->has_preallocation)
> +        preallocation = luks_opts->preallocation;
> +
>      ret = block_crypto_co_create_generic(bs, luks_opts->size, &create_opts,
> -                                         errp);
> +                                         preallocation, errp);
>      if (ret < 0) {
>          goto fail;
>      }
> @@ -534,12 +545,24 @@ static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
>      QCryptoBlockCreateOptions *create_opts = NULL;
>      BlockDriverState *bs = NULL;
>      QDict *cryptoopts;
> +    PreallocMode prealloc;
> +    char *buf = NULL;
>      int64_t size;
>      int ret;
> +    Error *local_err = NULL;
>  
>      /* Parse options */
>      size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
>  
> +    buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
> +    prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
> +                               PREALLOC_MODE_OFF, &local_err);
> +    g_free(buf);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return -EINVAL;
> +    }
> +
>      cryptoopts = qemu_opts_to_qdict_filtered(opts, NULL,
>                                               &block_crypto_create_opts_luks,
>                                               true);
> @@ -565,7 +588,7 @@ static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
>      }
>  
>      /* Create format layer */
> -    ret = block_crypto_co_create_generic(bs, size, create_opts, errp);
> +    ret = block_crypto_co_create_generic(bs, size, create_opts, prealloc, errp);
>      if (ret < 0) {
>          goto fail;
>      }
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 0d43d4f37c..ebcfc9f903 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -4205,13 +4205,16 @@
>  #
>  # @file             Node to create the image format on
>  # @size             Size of the virtual disk in bytes
> +# @preallocation    Preallocation mode for the new image (default: off;
> +#                   allowed values: off/falloc/full

Should we add also "metadata" to allowed values? and "since: 4.2"?
I'd like to have (just to have similar documentation with others
preallocation parameters):

  # @preallocation    Preallocation mode for the new image (default: off;
  #                   allowed values: off, falloc, full, metadata; since: 4.2)


Thanks,
Stefano