Re: [syzbot] kernel BUG in btrfs_subpage_assert

[syzbot]

> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

This crash does not have a reproducer. I cannot test it.

>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 558b4a3f9633..98ea6a9a67f3 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -10813,10 +10813,17 @@ static bool btrfs_data_dirty_folio(struct address_space *mapping,
>  	const u64 range_end = min_t(u64, folio_next_pos(folio),
>  				    round_up(i_size_read(&inode->vfs_inode),
>  					     fs_info->sectorsize));
> +	int ret;
>  
> -	if (range_end > page_start)
> +	if (range_end > page_start) {
> +		if (btrfs_is_subpage(fs_info, folio)) {
> +			ret = set_folio_extent_mapped(folio);
> +			if (ret < 0)
> +				return false;
> +		}
>  		btrfs_folio_set_fixup_dirty(fs_info, folio, page_start,
>  					    range_end - page_start);
> +	}
>  	return filemap_dirty_folio(mapping, folio);
>  }