Re: [PATCH v2] f2fs: another way to set large folio by remembering inode number

[Christoph Hellwig]

On Thu, May 21, 2026 at 06:42:03PM +0100, Matthew Wilcox wrote:
> On Thu, May 21, 2026 at 11:57:48AM -0400, Theodore Tso wrote:
> > So let me get this straight.  This is a magic xattr interface which is
> > not even persisted in the file system, but instead sets a 32-bit
> > bitmask in the struct inode which disappears once the inode gets
> > flushed from the inode stack.  And it uses a generic xattr name,
> > "user.fadvise".
> > 
> > There's no way in *hell* any other file system is likely to adopt such
> > a broken interface, so why didn't you just use an ioctl to set this
> > magic f2fs-specific flag?
> 
> I mean, yes, this API is horrendous.  But it's just another example of
> f2fs thinking it's somehow special and not just enabling large folios
> like other filesystems do.  This hurts everyone, not just people who use
> f2fs.

Yes.  And assuming we'd have a legit use to unconditionally use smaller
folios for given files we'd really need to control it in the MM.  Even
if it ends up being a Android-only hack.