Re: [PATCH RFC 4/5] btrfs: remove 2K block size support

[David Sterba <dsterba@suse.cz>]

On Fri, Apr 24, 2026 at 06:21:33PM +0930, Qu Wenruo wrote:
> Originally 2K block size support was introduced to test subpage (block
> size < page size) on x86_64 where the page size is exactly the original
> minimal block size.
> 
> However that 2K block size support has some problems:
> 
> - No 2K nodesize support
>   This is critical, as there is still no way to exercise the subpage
>   metadata routine.
> 
> - Very easy to test subpage data path now
>   With the currently experimental large folio support, it's very easy to
>   test the subpage data folio path already, as when a folio larger than
>   4K is encountered on x86_64, we will need all the subpage folio states
>   and bitmaps.
> 
>   So there is no need to use 2K block size just to verify subpage data
>   path even on x86_64.
> 
> And with the incoming huge folio (2M on x86_64) support, the 2K block
> size will easily double the bitmap size, considering the burden to
> maintain and the limited extra coverage, I believe it's time to remove
> it for the incoming huge folio support.

Ok then, the 2K support is inferior compared to the folio updates so off
it goes. You can add it now so you don't have to keep it in the series.