Re: [RFC PATCH v2 0/5] Add buffered write-through support to iomap & xfs

[Pankaj Raghav (Samsung)]

Thanks for the patches.

> The implementation of write-through combines the buffered IO frontend
> with dio backend, which leads to some interesting interactions.
> I've added most of the design notes in respective patches. Please note
> that this is an initial RFC to iron out any early design issues. This is
> largely based on suggestions from Dave an Jan in [1] so thanks for the
> pointers!
> 
> 
> * Testing Notes (UPDATED) *
> 
> - I've added support for RWF_WRITETHROUGH to fsx and fsstress in
>   xfstests and these patches survive fsx with integrity verification as
>   well as fsstress parallel stressing.

Could you point me to your xfstests repo where you have added this
support? :)
I have been traveling the whole week. I can give the patches a spin in
my setup in the coming days.

> - -g quick with blocks size == page size and blocksize < pagesize shows
>   no new regressions.
> 
> 
> * Design TODOs (UPDATED) *
> 
> - Evaluate if we need to tag page cache dirty bit in xarray, since 
>   PG_Writeback is already set on the folio.
> - Look into a better way to refactor writethrough path by reusing common
>   parts of dio code.
>