Commit f7470591 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: convert page_to_pgoff() to page_pgoff() 

Patch series "page->index removals in mm", v2.

As part of shrinking struct page, we need to stop using page->index.  This
patchset gets rid of most of the remaining references to page->index in
mm, as well as increasing the number of functions which take a const
folio/page pointer.  It shrinks the text segment of mm by a few hundred
bytes in my test config, probably mostly from removing calls to
compound_head() in page_to_pgoff().


This patch (of 7):

Change the function signature to pass in the folio as all three callers
have it.  This removes a reference to page->index, which we're trying to
get rid of.  And add kernel-doc.

Link: https://lkml.kernel.org/r/20241005200121.3231142-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20241005200121.3231142-2-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent e664c2cd

include/linux/mm.h

+1 −1
Original line number Diff line number Diff line
@@ -1895,7 +1895,7 @@ static inline unsigned long page_to_section(const struct page *page) 
 *

 * Return: The Page Frame Number of the first page in the folio.

 */

static inline unsigned long folio_pfn(struct folio *folio)

static inline unsigned long folio_pfn(const struct folio *folio)

{

	return page_to_pfn(&folio->page);

}

include/linux/pagemap.h

+17 −14
Original line number Diff line number Diff line
@@ -1011,22 +1011,25 @@ static inline struct folio *read_mapping_folio(struct address_space *mapping, 
	return read_cache_folio(mapping, index, NULL, file);

}



/*

 * Get the offset in PAGE_SIZE (even for hugetlb pages).

/**

 * page_pgoff - Calculate the logical page offset of this page.

 * @folio: The folio containing this page.

 * @page: The page which we need the offset of.

 *

 * For file pages, this is the offset from the beginning of the file

 * in units of PAGE_SIZE.  For anonymous pages, this is the offset from

 * the beginning of the anon_vma in units of PAGE_SIZE.  This will

 * return nonsense for KSM pages.

 *

 * Context: Caller must have a reference on the folio or otherwise

 * prevent it from being split or freed.

 *

 * Return: The offset in units of PAGE_SIZE.

 */

static inline pgoff_t page_to_pgoff(struct page *page)

static inline pgoff_t page_pgoff(const struct folio *folio,

		const struct page *page)

{

	struct page *head;



	if (likely(!PageTransTail(page)))

		return page->index;



	head = compound_head(page);

	/*

	 *  We don't initialize ->index for tail pages: calculate based on

	 *  head page

	 */

	return head->index + page - head;

	return folio->index + folio_page_idx(folio, page);

}



/*

mm/memory-failure.c

+2 −2
Original line number Diff line number Diff line
@@ -617,7 +617,7 @@ static void collect_procs_anon(struct folio *folio, struct page *page, 
	if (av == NULL)	/* Not actually mapped anymore */

		return;



	pgoff = page_to_pgoff(page);

	pgoff = page_pgoff(folio, page);

	rcu_read_lock();

	for_each_process(tsk) {

		struct vm_area_struct *vma;
@@ -653,7 +653,7 @@ static void collect_procs_file(struct folio *folio, struct page *page, 


	i_mmap_lock_read(mapping);

	rcu_read_lock();

	pgoff = page_to_pgoff(page);

	pgoff = page_pgoff(folio, page);

	for_each_process(tsk) {

		struct task_struct *t = task_early_kill(tsk, force_early);

		unsigned long addr;

mm/rmap.c

+1 −1
Original line number Diff line number Diff line
@@ -1276,7 +1276,7 @@ static void __page_check_anon_rmap(struct folio *folio, struct page *page, 
	 */

	VM_BUG_ON_FOLIO(folio_anon_vma(folio)->root != vma->anon_vma->root,

			folio);

	VM_BUG_ON_PAGE(page_to_pgoff(page) != linear_page_index(vma, address),

	VM_BUG_ON_PAGE(page_pgoff(folio, page) != linear_page_index(vma, address),

		       page);

}