Re: [PATCH v2 5/6] block-stream: add compress option

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

02.10.2019 17:22, Andrey Shinkevich wrote:
> Allow data compression during block-stream job for backup backing chain.
> 
> Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> ---
>   block/stream.c            | 19 +++++++++++++------
>   blockdev.c                | 14 +++++++++++++-
>   hmp-commands.hx           |  4 ++--
>   include/block/block_int.h |  3 ++-
>   monitor/hmp-cmds.c        |  5 +++--
>   qapi/block-core.json      |  5 ++++-
>   6 files changed, 37 insertions(+), 13 deletions(-)
> 
> diff --git a/block/stream.c b/block/stream.c
> index 5562ccb..51cc49e 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -36,15 +36,21 @@ typedef struct StreamBlockJob {
>       char *backing_file_str;
>       bool bs_read_only;
>       bool chain_frozen;
> +    bool compress;
>   } StreamBlockJob;
>   
> -static int coroutine_fn stream_populate(BlockBackend *blk,
> -                                        int64_t offset, uint64_t bytes)
> +static int coroutine_fn stream_populate(BlockBackend *blk, int64_t offset,
> +                                        uint64_t bytes, bool compress)
>   {
> +    int flags = BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH;

better: BdrvRequestFlags flags = ...

> +
> +    if (compress) {
> +        flags |= BDRV_REQ_WRITE_COMPRESSED;
> +    }
> +
>       assert(bytes < SIZE_MAX);
>   
> -    return blk_co_preadv(blk, offset, bytes, NULL,
> -                         BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
> +    return blk_co_preadv(blk, offset, bytes, NULL, flags);
>   }
>   
>   static void stream_abort(Job *job)
> @@ -167,7 +173,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
>           }
>           trace_stream_one_iteration(s, offset, n, ret);
>           if (copy) {
> -            ret = stream_populate(blk, offset, n);
> +            ret = stream_populate(blk, offset, n, s->compress);
>           }
>           if (ret < 0) {
>               BlockErrorAction action =
> @@ -217,7 +223,7 @@ static const BlockJobDriver stream_job_driver = {
>   
>   void stream_start(const char *job_id, BlockDriverState *bs,
>                     BlockDriverState *base, const char *backing_file_str,
> -                  int creation_flags, int64_t speed,
> +                  int creation_flags, int64_t speed, bool compress,
>                     BlockdevOnError on_error, Error **errp)
>   {
>       StreamBlockJob *s;
> @@ -267,6 +273,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
>       s->backing_file_str = g_strdup(backing_file_str);
>       s->bs_read_only = bs_read_only;
>       s->chain_frozen = true;
> +    s->compress = compress;

I'd prefer check for compress support to be in this function, not in the caller.

>   
>       s->on_error = on_error;
>       trace_stream_start(bs, base, s);
> diff --git a/blockdev.c b/blockdev.c
> index fbef684..290ee4b 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3238,6 +3238,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
>                         bool has_base_node, const char *base_node,
>                         bool has_backing_file, const char *backing_file,
>                         bool has_speed, int64_t speed,
> +                      bool has_compress, bool compress,
>                         bool has_on_error, BlockdevOnError on_error,
>                         bool has_auto_finalize, bool auto_finalize,
>                         bool has_auto_dismiss, bool auto_dismiss,
> @@ -3254,6 +3255,10 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
>           on_error = BLOCKDEV_ON_ERROR_REPORT;
>       }
>   
> +    if (!has_compress) {
> +        compress = false;
> +    }

This is extra thing: it's guaranteed for it to be false, if it is absent.

> +
>       bs = bdrv_lookup_bs(device, device, errp);
>       if (!bs) {
>           return;
> @@ -3308,6 +3313,12 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
>           goto out;
>       }
>   
> +    if (compress && bs->drv->bdrv_co_pwritev_compressed_part == NULL) {
> +        error_setg(errp, "Compression is not supported for this drive %s",
> +                   bdrv_get_device_name(bs));
> +        goto out;
> +    }
> +
>       /* backing_file string overrides base bs filename */
>       base_name = has_backing_file ? backing_file : base_name;
>   
> @@ -3319,7 +3330,8 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
>       }
>   
>       stream_start(has_job_id ? job_id : NULL, bs, base_bs, base_name,
> -                 job_flags, has_speed ? speed : 0, on_error, &local_err);
> +                 job_flags, has_speed ? speed : 0, compress, on_error,
> +                 &local_err);
>       if (local_err) {
>           error_propagate(errp, local_err);
>           goto out;
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index cfcc044..3a347fd 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -95,8 +95,8 @@ ETEXI
>   
>       {
>           .name       = "block_stream",
> -        .args_type  = "device:B,speed:o?,base:s?",
> -        .params     = "device [speed [base]]",
> +        .args_type  = "device:B,speed:o?,base:s?,compress:o?",
> +        .params     = "device [speed [base]] [compress]",
>           .help       = "copy data from a backing file into a block device",
>           .cmd        = hmp_block_stream,
>       },

I'm not a fan of contributing into hmp, and I don't remember the syntax of this file,
but I think it's wrong to define boolean field like interger speed...

> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 0422acd..5e7fce8 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -1065,6 +1065,7 @@ int is_windows_drive(const char *filename);
>    * @creation_flags: Flags that control the behavior of the Job lifetime.
>    *                  See @BlockJobCreateFlags
>    * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
> + * @compress: True to compress data.
>    * @on_error: The action to take upon error.
>    * @errp: Error object.
>    *
> @@ -1077,7 +1078,7 @@ int is_windows_drive(const char *filename);
>    */
>   void stream_start(const char *job_id, BlockDriverState *bs,
>                     BlockDriverState *base, const char *backing_file_str,
> -                  int creation_flags, int64_t speed,
> +                  int creation_flags, int64_t speed, bool compress,
>                     BlockdevOnError on_error, Error **errp);
>   
>   /**
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index b2551c1..91201fe 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -2025,11 +2025,12 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
>       const char *device = qdict_get_str(qdict, "device");
>       const char *base = qdict_get_try_str(qdict, "base");
>       int64_t speed = qdict_get_try_int(qdict, "speed", 0);
> +    bool compress = qdict_get_try_bool(qdict, "compress", false);
>   
>       qmp_block_stream(true, device, device, base != NULL, base, false, NULL,
>                        false, NULL, qdict_haskey(qdict, "speed"), speed, true,
> -                     BLOCKDEV_ON_ERROR_REPORT, false, false, false, false,
> -                     &error);
> +                     compress, true, BLOCKDEV_ON_ERROR_REPORT,
> +                     false, false, false, false, &error);
>   
>       hmp_handle_error(mon, &error);
>   }
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index e6edd64..9c2093e 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2544,6 +2544,9 @@
>   #
>   # @speed:  the maximum speed, in bytes per second
>   #
> +# @compress: true to compress data, if the target format supports it
> +#            (default: false). Since 4.2.
> +#
>   # @on-error: the action to take on an error (default report).
>   #            'stop' and 'enospc' can only be used if the block device
>   #            supports io-status (see BlockInfo).  Since 1.3.
> @@ -2576,7 +2579,7 @@
>   { 'command': 'block-stream',
>     'data': { '*job-id': 'str', 'device': 'str', '*base': 'str',
>               '*base-node': 'str', '*backing-file': 'str', '*speed': 'int',
> -            '*on-error': 'BlockdevOnError',
> +            '*compress': 'bool', '*on-error': 'BlockdevOnError',
>               '*auto-finalize': 'bool', '*auto-dismiss': 'bool' } }
>   
>   ##
> 


-- 
Best regards,
Vladimir