[PATCH 3/6] folio: Add a function to get the host inode for a folio

[Matthew Wilcox]

On Tue, Aug 24, 2021 at 02:25:11PM +0100, David Howells wrote:
> + * For folios which are in the page cache, return the inode that is hosting
> + * this folio belongs to.
> + *
> + * Do not call this for folios which aren't in the page cache.
> + */
> +static inline struct inode *folio_inode(struct folio *folio)
> +{
> +	return folio_file_mapping(folio)->host;

You're contradicting yourself here.  If you're allowed to call this
function for swap cache pages, then the documentation needs to change.
If you're not, then we can just use folio->mapping->host.