filemap: Add folio_put_wait_locked()

Convert all three callers of put_and_wait_on_page_locked() to
folio_put_wait_locked().  This shrinks the kernel overall by 19 bytes.
filemap_update_page() shrinks by 19 bytes while __migration_entry_wait()
is unchanged.  folio_put_wait_locked() is 14 bytes smaller than
put_and_wait_on_page_locked(), but pmd_migration_entry_wait() grows by
14 bytes.  It removes the assumption from pmd_migration_entry_wait()
that pages cannot be larger than a PMD (which is true today, but
may be interesting to explore in the future).

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>

1 files changed, 10 insertions, 11 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index cf25b00f03c8..311638177536 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -291,7 +291,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
 {
 	pte_t pte;
 	swp_entry_t entry;
-	struct page *page;
+	struct folio *folio;
 
 	spin_lock(ptl);
 	pte = *ptep;
@@ -302,18 +302,17 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
 	if (!is_migration_entry(entry))
 		goto out;
 
-	page = pfn_swap_entry_to_page(entry);
-	page = compound_head(page);
+	folio = page_folio(pfn_swap_entry_to_page(entry));
 
 	/*
 	 * Once page cache replacement of page migration started, page_count
-	 * is zero; but we must not call put_and_wait_on_page_locked() without
-	 * a ref. Use get_page_unless_zero(), and just fault again if it fails.
+	 * is zero; but we must not call folio_put_wait_locked() without
+	 * a ref. Use folio_try_get(), and just fault again if it fails.
 	 */
-	if (!get_page_unless_zero(page))
+	if (!folio_try_get(folio))
 		goto out;
 	pte_unmap_unlock(ptep, ptl);
-	put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
+	folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE);
 	return;
 out:
 	pte_unmap_unlock(ptep, ptl);
@@ -338,16 +337,16 @@ void migration_entry_wait_huge(struct vm_area_struct *vma,
 void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd)
 {
 	spinlock_t *ptl;
-	struct page *page;
+	struct folio *folio;
 
 	ptl = pmd_lock(mm, pmd);
 	if (!is_pmd_migration_entry(*pmd))
 		goto unlock;
-	page = pfn_swap_entry_to_page(pmd_to_swp_entry(*pmd));
-	if (!get_page_unless_zero(page))
+	folio = page_folio(pfn_swap_entry_to_page(pmd_to_swp_entry(*pmd)));
+	if (!folio_try_get(folio))
 		goto unlock;
 	spin_unlock(ptl);
-	put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
+	folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE);
 	return;
 unlock:
 	spin_unlock(ptl);