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

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:

quoted

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.