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

[David Sterba <dsterba@suse.cz>]

On Mon, Jan 29, 2024 at 08:16:05PM +1030, Qu Wenruo wrote:
> This is the conversion for btrfs compression paths to use folio
> interfaces.
> 
> For now, it's a pure intrefaces change, just with some variable names
> also changed from "page" to "folio".
> 
> There is no utilization of possible larger folio size yet, thus we're
> still using a lot of PAGE_SIZE/PAGE_SHIFT in the existing code.
> 
> But it's still a good first step towards large folio for btrfs data.
> 
> The first patch is in fact independent from the series, to slightly
> enhance the page cache missing error handling, but all later patches
> relies on it, to make later folio change a little smoother.
> 
> The third patch is also a good cleanup, as it allows we to pass a single
> page to inline creation path.
> Although during tests, it turns out that under heavy race we can try to
> insert an empty inline extent, but since the old code can handle it
> well, I just added one comment for it.
> 
> The remaining but the last one are some preparation before the final
> conversion.
> 
> 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.