Re: [PATCH v6 3/9] block: add emulation for copy

[Hannes Reinecke <hare@suse.de>]

On 1/12/23 15:46, Hannes Reinecke wrote:
> On 1/12/23 12:58, Nitesh Shetty wrote:
>> For the devices which does not support copy, copy emulation is
>> added. Copy-emulation is implemented by reading from source ranges
>> into memory and writing to the corresponding destination asynchronously.
>> For zoned device we maintain a linked list of read submission and try to
>> submit corresponding write in same order.
>> Also emulation is used, if copy offload fails or partially completes.
>>
>> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
>> Signed-off-by: Vincent Fu <vincent.fu@samsung.com>
>> Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
>> ---
>>   block/blk-lib.c        | 241 ++++++++++++++++++++++++++++++++++++++++-
>>   block/blk-map.c        |   4 +-
>>   include/linux/blkdev.h |   3 +
>>   3 files changed, 245 insertions(+), 3 deletions(-)
>>
> I'm not sure if I agree with this one.
> 
> You just submitted a patch for device-mapper to implement copy offload, 
> which (to all intents and purposes) _is_ an emulation.
> 
> So why do we need to implement it in the block layer as an emulation?
> Or, if we have to, why do we need the device-mapper emulation?
> This emulation will be doing the same thing, no?
> 
Sheesh. One should read the entire patchset.

Disregard the above comment.

Cheers,

Hannes