Re: [Qemu-devel] [PATCH 1/2] The discard flag for block stream operation

[Andrey Shinkevich]

OK, David,

I will implement that with the next series.

Kindly,

Andrey Shinkevich


On 31.10.2018 20:38, Dr. David Alan Gilbert wrote:
> * Andrey Shinkevich (address@hidden) wrote:
>> Adding a parameter to QMP block-stream command to allow discarding
>> blocks in the backing chain while blocks are being copied to the
>> active layer.
>>
>> Signed-off-by: Andrey Shinkevich <address@hidden>
>> ---
>>   block/stream.c            | 2 +-
>>   blockdev.c                | 8 +++++++-
>>   hmp-commands.hx           | 4 ++--
>>   hmp.c                     | 4 +++-
>>   include/block/block_int.h | 2 +-
>>   qapi/block-core.json      | 5 ++++-
>>   6 files changed, 18 insertions(+), 7 deletions(-)
>>
>> diff --git a/block/stream.c b/block/stream.c
>> index 81a7ec8..db81df4 100644
>> --- a/block/stream.c
>> +++ b/block/stream.c
>> @@ -221,7 +221,7 @@ 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 discard,
>>                     BlockdevOnError on_error, Error **errp)
>>   {
>>       StreamBlockJob *s;
>> diff --git a/blockdev.c b/blockdev.c
>> index 574adbc..04aecf5 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -3122,6 +3122,7 @@ 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_discard, bool discard,
>>                         bool has_on_error, BlockdevOnError on_error,
>>                         bool has_auto_finalize, bool auto_finalize,
>>                         bool has_auto_dismiss, bool auto_dismiss,
>> @@ -3138,6 +3139,10 @@ void qmp_block_stream(bool has_job_id, const char 
>> *job_id, const char *device,
>>           on_error = BLOCKDEV_ON_ERROR_REPORT;
>>       }
>>   
>> +    if (!has_discard) {
>> +        discard = false;
>> +    }
>> +
>>       bs = bdrv_lookup_bs(device, device, errp);
>>       if (!bs) {
>>           return;
>> @@ -3202,7 +3207,8 @@ 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,
>> +                 discard, 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 db0c681..b455e0d 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?,discard:o?",
> I think that 'o?' is wrong - see the table at the top of monitor.c, 'o'
> is octets, ? is optional - so speed here is an optional byte count, I
> think your 'discard' is just an optional flag.
> So I think you'd be better with a flag, like the -f on block_job_cancel.
>
>> +        .params     = "device [speed [base]] [discard]",
>>           .help       = "copy data from a backing file into a block device",
>>           .cmd        = hmp_block_stream,
>>       },
>> diff --git a/hmp.c b/hmp.c
>> index 7828f93..c63e806 100644
>> --- a/hmp.c
>> +++ b/hmp.c
>> @@ -1920,9 +1920,11 @@ 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 discard = qdict_get_try_bool(qdict, "discard", false);
>>   
>>       qmp_block_stream(true, device, device, base != NULL, base, false, NULL,
>> -                     false, NULL, qdict_haskey(qdict, "speed"), speed, true,
>> +                     false, NULL, qdict_haskey(qdict, "speed"), speed,
>> +                     qdict_haskey(qdict, "discard"), discard, true,
> Since you've got the default 'false' on the bool discard =   above, I
> wonder if that can just be   true, discard, true    ?
>
> Dave
>
>>                        BLOCKDEV_ON_ERROR_REPORT, false, false, false, false,
>>                        &error);
>>   
>> diff --git a/include/block/block_int.h b/include/block/block_int.h
>> index 92ecbd8..e531d03 100644
>> --- a/include/block/block_int.h
>> +++ b/include/block/block_int.h
>> @@ -970,7 +970,7 @@ 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 discard,
>>                     BlockdevOnError on_error, Error **errp);
>>   
>>   /**
>> diff --git a/qapi/block-core.json b/qapi/block-core.json
>> index cfb37f8..3f50b88 100644
>> --- a/qapi/block-core.json
>> +++ b/qapi/block-core.json
>> @@ -2329,6 +2329,9 @@
>>   #
>>   # @speed:  the maximum speed, in bytes per second
>>   #
>> +# @discard: true to delete blocks duplicated in old backing files.
>> +#           (default: false). Since 3.1.
>> +#
>>   # @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.
>> @@ -2361,7 +2364,7 @@
>>   { 'command': 'block-stream',
>>     'data': { '*job-id': 'str', 'device': 'str', '*base': 'str',
>>               '*base-node': 'str', '*backing-file': 'str', '*speed': 'int',
>> -            '*on-error': 'BlockdevOnError',
>> +            '*discard': 'bool', '*on-error': 'BlockdevOnError',
>>               '*auto-finalize': 'bool', '*auto-dismiss': 'bool' } }
>>   
>>   ##
>> -- 
>> 1.8.3.1
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK