mm: use page_pgoff() in more places

There are several places which currently open-code page_pgoff(), convert
them to call it.

Link: https://lkml.kernel.org/r/20241005200121.3231142-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Matthew Wilcox (Oracle)

kernel/futex/core.c

@@ -399,7 +399,7 @@ int get_futex_key(u32 __user *uaddr, unsigned int flags, union futex_key *key,
 
 		key->both.offset |= FUT_OFF_INODE; /* inode-based key */
 		key->shared.i_seq = get_inode_sequence_number(inode);
-		key->shared.pgoff = folio->index + folio_page_idx(folio, page);
+		key->shared.pgoff = page_pgoff(folio, page);
 		rcu_read_unlock();
 	}
 

mm/page_vma_mapped.c

@@ -340,15 +340,14 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 unsigned long page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
 {
 	struct folio *folio = page_folio(page);
-	pgoff_t pgoff = folio->index + folio_page_idx(folio, page);
 	struct page_vma_mapped_walk pvmw = {
 		.pfn = page_to_pfn(page),
 		.nr_pages = 1,
 		.vma = vma,
 		.flags = PVMW_SYNC,
 	};
 
-	pvmw.address = vma_address(vma, pgoff, 1);
+	pvmw.address = vma_address(vma, page_pgoff(folio, page), 1);
 	if (pvmw.address == -EFAULT)
 		goto out;
 	if (!page_vma_mapped_walk(&pvmw))

mm/rmap.c

@@ -774,7 +774,6 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 {
 	struct folio *folio = page_folio(page);
-	pgoff_t pgoff;
 
 	if (folio_test_anon(folio)) {
 		struct anon_vma *page__anon_vma = folio_anon_vma(folio);
@@ -792,8 +791,7 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 	}
 
 	/* The !page__anon_vma above handles KSM folios */
-	pgoff = folio->index + folio_page_idx(folio, page);
-	return vma_address(vma, pgoff, 1);
+	return vma_address(vma, page_pgoff(folio, page), 1);
 }
 
 /*