On Fri, Apr 4, 2014 at 4:53 PM, David Sterba <dsterba@xxxxxxx> wrote:
> On Fri, Apr 04, 2014 at 04:20:41PM +0100, Filipe David Borba Manana wrote:
>> @@ -4307,6 +4348,22 @@ out:
>> return num_read;
>> }
>>
>> +static int send_total_data_size(struct send_ctx *sctx, u64 data_size)
>> +{
>> + int ret;
>> +
>> + ret = begin_cmd(sctx, BTRFS_SEND_C_TOTAL_DATA_SIZE);
>> + if (ret < 0)
>> + goto out;
>> +
>> + TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, data_size);
>> + ret = send_cmd(sctx);
>> +
>> +tlv_put_failure:
>> +out:
>> + return ret;
>> +}
>> +
>> /*
>> * Send a clone command to user space.
>> */
>> --- a/fs/btrfs/send.h
>> +++ b/fs/btrfs/send.h
>> @@ -87,6 +87,7 @@ enum btrfs_send_cmd {
>>
>> BTRFS_SEND_C_END,
>> BTRFS_SEND_C_UPDATE_EXTENT,
>> + BTRFS_SEND_C_TOTAL_DATA_SIZE,
>
> Though it is a simple modification, it changes the existing send
> protocol.
>
> The unpatched receiver would fail (it has a lower value of
> __BTRFS_SEND_C_MAX), so it could work even without revving the protocol.
> But, it's not the cleanest way.
Same problem happened when BTRFS_SEND_C_UPDATE_EXTENT was added.
Since it's a command that's only sent if a new special flag is
supplied, I don't think it's that bad.
>
> There's a number of defficiencies found in v1 protocol, see
> https://btrfs.wiki.kernel.org/index.php/Design_notes_on_Send/Receive#Send_stream_v2_draft
>
> I would rather see a proper v2 revision instead of relying on the fact
> that current implementation will deal with the change.
Right, by 2020 we'll have v2 fully specified and maybe implemented :)
Thanks David
>
>> __BTRFS_SEND_C_MAX,
>> };
>> #define BTRFS_SEND_C_MAX (__BTRFS_SEND_C_MAX - 1)
--
Filipe David Manana,
"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
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