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

Jaegeuk Kim via Linux-f2fs-devel
2026-04-13T22:47:31Z

On 04/13, Chao Yu wrote:
> On 4/9/2026 2:13 AM, Jaegeuk Kim via Linux-f2fs-devel wrote:
> > Let's check mmap writes onto the large folio, since we don't support writing
> > large folios.
> >
> > Reviewed-by: Daeho Jeong <daehojeong@google.com>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> >
> > - log v2:
> > : add comments
> >
> > fs/f2fs/file.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 2c4880f24b54..c0220cd7b332 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -82,7 +82,12 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
> > int err = 0;
> > vm_fault_t ret;
> > - if (unlikely(IS_IMMUTABLE(inode)))
> > + /*
> > + * We only support large folio on the read case.
> > + * Don't make any dirty pages.
> > + */
> > + if (unlikely(IS_IMMUTABLE(inode)) ||
> > + mapping_large_folio_support(inode->i_mapping))
> > return VM_FAULT_SIGBUS;
>
> The code itself looks good, since it's an impossible case, should we
> use f2fs_bug_on(, mapping_large_folio_support()) to catch any bug case
> rather than just returning error here w/o log?

Instead of kernel panicing for the production, I'd leave a kernel message first.

>
> Thanks,
>
> > if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {