Re: [PATCH v2 04/10] hugetlb: Set mapping folio order

[Usama Arif <usama.arif@linux.dev>]

On Thu,  9 Jul 2026 19:47:32 +0100 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:

> hugetlbfs currently uses an fs-specific way to determine the size of
> the folios in its page cache.  Thanks to the support of block sizes
> larger than page sizes, we now support this as part of the page cache.
> It's somewhat more efficient as we have this information directly in the
> mapping rather than going from inode->i_sb->s_fs_info.  We can convert
> the rest of the hugetlb code to use this at our leisure; this is needed
> now so that we can use filemap_get_pages() unmodified.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  fs/hugetlbfs/inode.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 216e1a0dd0b2..1760df6f2709 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -883,6 +883,16 @@ static struct inode *hugetlbfs_get_root(struct super_block *sb,
>  	return inode;
>  }
>  
> +static void hugetlbfs_init_regular_inode(struct inode *inode)
> +{
> +	struct hstate *hstate = hstate_inode(inode);
> +	unsigned int order = huge_page_order(hstate);
> +
> +	inode->i_op = &hugetlbfs_inode_operations;
> +	inode->i_fop = &hugetlbfs_file_operations;
> +	mapping_set_folio_order_range(inode->i_mapping, order, order);

We are setting mapping_set_folio_order_range(), but mapping_min_folio_order()
and mapping_max_folio_order() will still return 0 if CONFIG_TRANSPARENT_HUGEPAGE
is disabled but hugetlb is enabled. I am guessing this will be tackled in
one of the following patches in the series.

> +}
> +
>  /*
>   * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
>   * be taken from reclaim -- unlike regular filesystems. This needs an
> @@ -926,8 +936,7 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb,
>  			init_special_inode(inode, mode, dev);
>  			break;
>  		case S_IFREG:
> -			inode->i_op = &hugetlbfs_inode_operations;
> -			inode->i_fop = &hugetlbfs_file_operations;
> +			hugetlbfs_init_regular_inode(inode);
>  			break;
>  		case S_IFDIR:
>  			inode->i_op = &hugetlbfs_dir_inode_operations;
> -- 
> 2.47.3
> 
>