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

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 05/21, Theodore Tso wrote:
> On Thu, May 21, 2026 at 01:51:08AM -0700, Christoph Hellwig wrote:
> > > You haven't sent a proposal.  This is a reply to a reply to a reply of a
> > > patch.  There's no justification for why f2fs is so special that it
> > > needs this.  What the hell is going on?  You know this is not the way to
> > > get code merged into Linux.
> > 
> > None of this got properly answers, and this broken interface now landed
> > in linux-next. IT is offloading a user.* xattr which is free-form
> > user data with semantics that are weird to say it very nicely.
> > 
> > All this was done against the advice in the mailing list discussion.
> 
> 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 went this route because Android heavily restricts ioctl() permissions
and we needed broader access for this to work within the framework. It’s
definitely a pragmatic choice just to get it running in production.

If ioctl() is a right way for upstream, I'm happy to change this patch. By
the way, I really don't understand why all the messages are so offensive,
even without trying to understand the problem or guiding right directions.

> 
> > I think at some point we just need to stop taking f2fs updates likes
> > this.
> 
> Well, that's ultiamtely up to Linus.  I'll say that if I were Linus
> (and I'm glad I'm not :-), and I saw this in a pull request, I'd
> reject it out of hand.  But whether it's worth making a huge fuss and
> asking escalating this mess to Linus, we probably should get a bit
> more community consensus before taking such a drastic step.

Could I also raise a quick concern regarding the phrasing/wording used
in the communications?

> 
> Christian, since you're one of the VFS maintaienrs, what's your
> opinion about escalating this to Linus?
> 
> 					- Ted
> 
> 
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