Re: [PATCH 0/6] btrfs: compression: migrate to folio interfaces

[David Sterba <dsterba@suse.cz>]

On Thu, Mar 28, 2024 at 12:52:39PM +1030, Qu Wenruo wrote:
> >> And the final patch is the core conversion, as we have several structure
> >> relying on page array, it's impossible to just convert one algorithm to
> >> folio meanwhile keep all the other using pages.
> >>
> >>
> >> Qu Wenruo (6):
> >>    btrfs: compression: add error handling for missed page cache
> >>    btrfs: compression: convert page allocation to folio interfaces
> >>    btrfs: make insert_inline_extent() to accept one page directly
> >>    btrfs: migrate insert_inline_extent() to folio interfaces
> >>    btrfs: introduce btrfs_alloc_folio_array()
> >>    btrfs: compression: migrate compression/decompression paths to folios
> >
> > I added this patchset to my misc-next and it was in linux-next until
> > now. The bug that was a blocker for folio conversions is now fixed,
> > also thanks to you, so we can continue with the conversions. As this
> > patchset is 2 months old I'm not sure if it would be helpful to start
> > commenting and do the normal iteration round, I did a review and style
> > fixup round and moved it to for-next. Please have a look and let me know
> > if you find something wrong. I did mostly whitespace changes, though I
> > did remove the ASSERT(0), if there's btrfs_crit message it's quite
> > noticeable, and removed the local variable for fs_info in the first one.
> >
> > The conversions are all direct and seem safe to me, we won't do
> > multi-page folios yet, so the intemediate steps are the right way to go.
> > Thanks.
> >
> 
> Well, since I'm reading through all the commits in misc-next, I found
> some typos from myself:
> 
> - btrfs: prefer to allocate larger folio for metadata
>    * No longer no smaller, must be an exact fit.
>      No larger no smaller, ...
> 
>    * So here we go a different workaround, allocate a order 2 folio first
>                                        ... allocate an order 2 ...

I have this patch only for testing and did not do a typo-fixing pass as
updates are still expected. Also I found some problems with this patch
in page migration, I've sent the logs to slack.

> And these patches must be dropped:
> 
> - btrfs: defrag: prepare defrag for larger data folio size
> - btrfs: introduce cached folio size
> 
>    These two introduced and utilize fs_info->folio_shift, for filemap
>    code, which is completely wrong. As filemap always expect an index
>    with PAGE_SHIFT.

Ok, will drop them.