[PATCH 0/4] Remove FGP_HEAD flag

[PATCH 0/4] Remove FGP_HEAD flag

[Matthew Wilcox (Oracle)]

We have just two users left of the FGP_HEAD flag and both of them are
better off; sometimes startlingly so as a result of conversion to use
folios.  Tested with a few xfstests runs, which complete successfully
except for new failures induced by updated tooling.

Matthew Wilcox (Oracle) (4):
  mm/huge_memory: Convert split_huge_pages_in_file() to use a folio
  mm/swap: Convert find_get_incore_page to use folios
  mm: Convert find_get_incore_page() to filemap_get_incore_folio()
  mm: Remove FGP_HEAD

 include/linux/pagemap.h |  5 ++---
 mm/folio-compat.c       |  2 +-
 mm/huge_memory.c        | 18 +++++++++---------
 mm/memcontrol.c         | 12 +++++++++---
 mm/mincore.c            | 10 +++++-----
 mm/swap.h               |  8 +++++---
 mm/swap_state.c         | 28 ++++++++++++++--------------
 7 files changed, 45 insertions(+), 38 deletions(-)

-- 
2.35.1

[PATCH 1/4] mm/huge_memory: Convert split_huge_pages_in_file() to use a folio

[Matthew Wilcox (Oracle)]

Removes a number of calls to compound_head() and a call to
pagecache_get_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/huge_memory.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1cc4a5f4791e..6d9ca4819d68 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3057,28 +3057,28 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
 	mapping = candidate->f_mapping;
 
 	for (index = off_start; index < off_end; index += nr_pages) {
-		struct page *fpage = pagecache_get_page(mapping, index,
-						FGP_ENTRY | FGP_HEAD, 0);
+		struct folio *folio = __filemap_get_folio(mapping, index,
+						FGP_ENTRY, 0);
 
 		nr_pages = 1;
-		if (xa_is_value(fpage) || !fpage)
+		if (xa_is_value(folio) || !folio)
 			continue;
 
-		if (!is_transparent_hugepage(fpage))
+		if (!folio_test_large(folio))
 			goto next;
 
 		total++;
-		nr_pages = thp_nr_pages(fpage);
+		nr_pages = folio_nr_pages(folio);
 
-		if (!trylock_page(fpage))
+		if (!folio_trylock(folio))
 			goto next;
 
-		if (!split_huge_page(fpage))
+		if (!split_folio(folio))
 			split++;
 
-		unlock_page(fpage);
+		folio_unlock(folio);
 next:
-		put_page(fpage);
+		folio_put(folio);
 		cond_resched();
 	}
 
-- 
2.35.1

[PATCH 2/4] mm/swap: Convert find_get_incore_page to use folios

[Matthew Wilcox (Oracle)]

Eliminates a use of FGP_HEAD and saves 35 bytes of text.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/swap_state.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 438d0676c5be..44e3530520e8 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -386,17 +386,14 @@ struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
 {
 	swp_entry_t swp;
 	struct swap_info_struct *si;
-	struct page *page = pagecache_get_page(mapping, index,
-						FGP_ENTRY | FGP_HEAD, 0);
+	struct folio *folio = __filemap_get_folio(mapping, index, FGP_ENTRY, 0);
 
-	if (!page)
-		return page;
-	if (!xa_is_value(page))
-		return find_subpage(page, index);
+	if (!xa_is_value(folio))
+		goto out;
 	if (!shmem_mapping(mapping))
 		return NULL;
 
-	swp = radix_to_swp_entry(page);
+	swp = radix_to_swp_entry(folio);
 	/* There might be swapin error entries in shmem mapping. */
 	if (non_swap_entry(swp))
 		return NULL;
@@ -404,9 +401,13 @@ struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
 	si = get_swap_device(swp);
 	if (!si)
 		return NULL;
-	page = find_get_page(swap_address_space(swp), swp_offset(swp));
+	index = swp_offset(swp);
+	folio = filemap_get_folio(swap_address_space(swp), index);
 	put_swap_device(si);
-	return page;
+out:
+	if (!folio)
+		return NULL;
+	return folio_file_page(folio, index);
 }
 
 struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
-- 
2.35.1

[PATCH 3/4] mm: Convert find_get_incore_page() to filemap_get_incore_folio()

[Matthew Wilcox (Oracle)]

Return the containing folio instead of the precise page.  One of the
callers wants the folio and the other can do the folio->page conversion
itself.  Nets 442 bytes of text size reduction, 478 bytes removed
and 36 bytes added.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/memcontrol.c | 12 +++++++++---
 mm/mincore.c    | 10 +++++-----
 mm/swap.h       |  8 +++++---
 mm/swap_state.c | 15 +++++++--------
 4 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2d8549ae1b30..2e6e8bce1f60 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5648,15 +5648,21 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
 static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
 			unsigned long addr, pte_t ptent)
 {
+	unsigned long index;
+	struct folio *folio;
+
 	if (!vma->vm_file) /* anonymous vma */
 		return NULL;
 	if (!(mc.flags & MOVE_FILE))
 		return NULL;
 
-	/* page is moved even if it's not RSS of this task(page-faulted). */
+	/* folio is moved even if it's not RSS of this task(page-faulted). */
 	/* shmem/tmpfs may report page out on swap: account for that too. */
-	return find_get_incore_page(vma->vm_file->f_mapping,
-			linear_page_index(vma, addr));
+	index = linear_page_index(vma, addr);
+	folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index);
+	if (!folio)
+		return NULL;
+	return folio_file_page(folio, index);
 }
 
 /**
diff --git a/mm/mincore.c b/mm/mincore.c
index fa200c14185f..7bf2803e03c6 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -52,7 +52,7 @@ static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
 static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
 {
 	unsigned char present = 0;
-	struct page *page;
+	struct folio *folio;
 
 	/*
 	 * When tmpfs swaps out a page from a file, any process mapping that
@@ -60,10 +60,10 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
 	 * any other file mapping (ie. marked !present and faulted in with
 	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
 	 */
-	page = find_get_incore_page(mapping, index);
-	if (page) {
-		present = PageUptodate(page);
-		put_page(page);
+	folio = filemap_get_incore_folio(mapping, index);
+	if (folio) {
+		present = folio_test_uptodate(folio);
+		folio_put(folio);
 	}
 
 	return present;
diff --git a/mm/swap.h b/mm/swap.h
index cc08c459c619..f78065c8ef52 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -41,7 +41,8 @@ void clear_shadow_from_swap_cache(int type, unsigned long begin,
 				  unsigned long end);
 struct folio *swap_cache_get_folio(swp_entry_t entry,
 		struct vm_area_struct *vma, unsigned long addr);
-struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
+struct folio *filemap_get_incore_folio(struct address_space *mapping,
+		pgoff_t index);
 
 struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 				   struct vm_area_struct *vma,
@@ -105,9 +106,10 @@ static inline struct folio *swap_cache_get_folio(swp_entry_t entry,
 }
 
 static inline
-struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
+struct folio *filemap_get_incore_folio(struct address_space *mapping,
+		pgoff_t index)
 {
-	return find_get_page(mapping, index);
+	return filemap_get_folio(mapping, index);
 }
 
 static inline bool add_to_swap(struct folio *folio)
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 44e3530520e8..40fe6f23e105 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -373,16 +373,17 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
 }
 
 /**
- * find_get_incore_page - Find and get a page from the page or swap caches.
+ * filemap_get_incore_folio - Find and get a folio from the page or swap caches.
  * @mapping: The address_space to search.
  * @index: The page cache index.
  *
- * This differs from find_get_page() in that it will also look for the
- * page in the swap cache.
+ * This differs from filemap_get_folio() in that it will also look for the
+ * folio in the swap cache.
  *
- * Return: The found page or %NULL.
+ * Return: The found folio or %NULL.
  */
-struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
+struct folio *filemap_get_incore_folio(struct address_space *mapping,
+		pgoff_t index)
 {
 	swp_entry_t swp;
 	struct swap_info_struct *si;
@@ -405,9 +406,7 @@ struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
 	folio = filemap_get_folio(swap_address_space(swp), index);
 	put_swap_device(si);
 out:
-	if (!folio)
-		return NULL;
-	return folio_file_page(folio, index);
+	return folio;
 }
 
 struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
-- 
2.35.1

[PATCH 4/4] mm: Remove FGP_HEAD

[Matthew Wilcox (Oracle)]

This is no longer used; all callers have been converted to use folios
instead.  Somehow this manages to save 11 bytes of text.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/pagemap.h | 5 ++---
 mm/folio-compat.c       | 2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index bbccb4044222..f690c979913d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -504,9 +504,8 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
 #define FGP_NOFS		0x00000010
 #define FGP_NOWAIT		0x00000020
 #define FGP_FOR_MMAP		0x00000040
-#define FGP_HEAD		0x00000080
-#define FGP_ENTRY		0x00000100
-#define FGP_STABLE		0x00000200
+#define FGP_ENTRY		0x00000080
+#define FGP_STABLE		0x00000100
 
 struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 		int fgp_flags, gfp_t gfp);
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index e1e23b4947d7..4eab4e505e85 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -108,7 +108,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
 	struct folio *folio;
 
 	folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
-	if ((fgp_flags & FGP_HEAD) || !folio || xa_is_value(folio))
+	if (!folio || xa_is_value(folio))
 		return &folio->page;
 	return folio_file_page(folio, index);
 }
-- 
2.35.1