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

[Chao Yu]

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@xxxxxxxxxx>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
>
>   - 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?

Thanks,

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