On Tue, Jan 21, 2020 at 09:21:18PM -0800, Jerome Glisse wrote:

<snip>

The block device code only need the mapping on io error and they are
different strategy depending on individual fs. fs using buffer_head
can easily be updated. For other they are different solution and they
can be updated one at a time with tailor solution.

If I did't misunderstand, how about post-processing fs code without
some buffer_head but page->private used as another way rather than
a pointer? (Yes, some alternative ways exist such as hacking struct
bio_vec...)

I wonder the final plan on this from the community, learn new rule
and adapt my code anyway.. But in my opinion, such reserve way
(page->mapping likewise) is helpful in many respects, I'm not sure
we could totally get around all cases without it elegantly...

Thank you...

Thanks,
Gao Xiang