Re: [f2fs-dev] [PATCH v3] f2fs: do not support mmap write for large folio

Jaegeuk Kim via Linux-f2fs-devel
2026-04-10T01:15:50Z

On 04/08, Christoph Hellwig wrote:
> [adding back fsdevel and mm to the discussion]
>
> On Wed, Apr 08, 2026 at 06:13:06PM +0000, Jaegeuk Kim wrote:
> > Let's check mmap writes onto the large folio, since we don't support writing
> > large folios.
>
> What does this fix? As state in the previous round of discussion f2fs
> only support large folios for immutable files, how do you get ->mkwrite
> called for them.

I'm approaching this as a safeguard first, since in any buggy case, this will
crash the filesystem.

>
> The only way I can think of that is when clearing the immutable flag,
> but simply rejecting writes with SIGBUS after that seems like it's
> breaking the expected API, and I don't see handling for normal writes
> after that either.