Commit 9257e156 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/filemap: Add folio_index(), folio_file_page() and folio_contains() 



folio_index() is the equivalent of page_index() for folios.
folio_file_page() is the equivalent of find_subpage().
folio_contains() is the equivalent of thp_contains().

No changes to generated code.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarJeff Layton <jlayton@kernel.org>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
parent 85d0a2ed

include/linux/pagemap.h

+56 −0
Original line number Diff line number Diff line
@@ -386,6 +386,62 @@ static inline bool thp_contains(struct page *head, pgoff_t index) 
	return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));

}



#define swapcache_index(folio)	__page_file_index(&(folio)->page)



/**

 * folio_index - File index of a folio.

 * @folio: The folio.

 *

 * For a folio which is either in the page cache or the swap cache,

 * return its index within the address_space it belongs to.  If you know

 * the page is definitely in the page cache, you can look at the folio's

 * index directly.

 *

 * Return: The index (offset in units of pages) of a folio in its file.

 */

static inline pgoff_t folio_index(struct folio *folio)

{

        if (unlikely(folio_test_swapcache(folio)))

                return swapcache_index(folio);

        return folio->index;

}



/**

 * folio_file_page - The page for a particular index.

 * @folio: The folio which contains this index.

 * @index: The index we want to look up.

 *

 * Sometimes after looking up a folio in the page cache, we need to

 * obtain the specific page for an index (eg a page fault).

 *

 * Return: The page containing the file data for this index.

 */

static inline struct page *folio_file_page(struct folio *folio, pgoff_t index)

{

	/* HugeTLBfs indexes the page cache in units of hpage_size */

	if (folio_test_hugetlb(folio))

		return &folio->page;

	return folio_page(folio, index & (folio_nr_pages(folio) - 1));

}



/**

 * folio_contains - Does this folio contain this index?

 * @folio: The folio.

 * @index: The page index within the file.

 *

 * Context: The caller should have the page locked in order to prevent

 * (eg) shmem from moving the page between the page cache and swap cache

 * and changing its index in the middle of the operation.

 * Return: true or false.

 */

static inline bool folio_contains(struct folio *folio, pgoff_t index)

{

	/* HugeTLBfs indexes the page cache in units of hpage_size */

	if (folio_test_hugetlb(folio))

		return folio->index == index;

	return index - folio_index(folio) < folio_nr_pages(folio);

}



/*

 * Given the page we found in the page cache, return the page corresponding

 * to this index in the file