On 2020/10/27 下午6:29, David Sterba wrote:
> On Wed, Oct 21, 2020 at 02:24:59PM +0800, Qu Wenruo wrote:
>> In end_bio_extent_readpage() we had a strange dance around
>> extent_start/extent_len.
>>
>> The truth is, no matter what we're doing using those two variable, the
>> end result is just the same, clear the EXTENT_LOCKED bit and if needed
>> set the EXTENT_UPTODATE bit for the io_tree.
>>
>> This doesn't need the complex dance, we can do it pretty easily by just
>> calling endio_readpage_release_extent() for each bvec.
>>
>> This greatly streamlines the code.
> 
> Yes it does, the old code is a series of conditions and new code is just
> one call but it's hard to see why this is correct. Can you please write
> some guidance, what are the invariants or how does the logic simplify?
> What you write above is a summary but for review I'd need something to
> follow so I don't have to spend too much time reading just this patch.
> Thanks.
> 
Sorry, I should add more explanation on that, would add that in next update.

Thanks,
Qu