Re: [PATCH 0/4] null_blk: usr memcpy_[to|from]_page()

[Jens Axboe <axboe@kernel.dk>]

On 3/30/23 12:56?PM, Chaitanya Kulkarni wrote:
> On 3/29/23 15:48, Jens Axboe wrote:
>> On 3/29/23 2:46?PM, Chaitanya Kulkarni wrote:
>>> Hi,
>>>
>>>  From :include/linux/highmem.h:
>>> "kmap_atomic - Atomically map a page for temporary usage - Deprecated!"
>>>
>>> Use memcpy_from_page() since does the same job of mapping, copying, and
>>> unmaping except it uses non deprecated kmap_local_page() and
>>> kunmap_local(). Following are the differences between kmal_local_page()
>>> and kmap_atomic() :-
>> Looks fine to me, but I'd fold patches 1-3 rather than split them up.
>>
> 
> Sent V2 with above comment, first three patches are from
> different code path and they are doing unrelated changes:-
> 
> 1. WRITE :- copy_to_nullb() only use memcpy_page().
> 2. READ :- copy_from_nullb() only use memcapy_page() and zero_user().
> 3. I guess zoned read beyond write pointer null_fill_pattern()
>     memset_page().
> 
> if anything goes wrong in any of 3 code paths we will have to
> entire change which we shouldn't, that's why kept it separate,
> I'm fine with whatever you decide ...

It doesn't matter... It's not like this is a hugely complicated thing.
It's just a straight forward conversion. They all just switch to using a
helper, which is the right thing to do as it reduces the stuff we have
to do in there. Only reason why I excluded patch 4 is that it is a bit
different than the others. But it really could just be one patch.

-- 
Jens Axboe