Merge tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache

Pull memory folios from Matthew Wilcox:
 "Add memory folios, a new type to represent either order-0 pages or the
  head page of a compound page. This should be enough infrastructure to
  support filesystems converting from pages to folios.

  The point of all this churn is to allow filesystems and the page cache
  to manage memory in larger chunks than PAGE_SIZE. The original plan
  was to use compound pages like THP does, but I ran into problems with
  some functions expecting only a head page while others expect the
  precise page containing a particular byte.

  The folio type allows a function to declare that it's expecting only a
  head page. Almost incidentally, this allows us to remove various calls
  to VM_BUG_ON(PageTail(page)) and compound_head().

  This converts just parts of the core MM and the page cache. For 5.17,
  we intend to convert various filesystems (XFS and AFS are ready; other
  filesystems may make it) and also convert more of the MM and page
  cache to folios. For 5.18, multi-page folios should be ready.

  The multi-page folios offer some improvement to some workloads. The
  80% win is real, but appears to be an artificial benchmark (postgres
  startup, which isn't a serious workload). Real workloads (eg building
  the kernel, running postgres in a steady state, etc) seem to benefit
  between 0-10%. I haven't heard of any performance losses as a result
  of this series. Nobody has done any serious performance tuning; I
  imagine that tweaking the readahead algorithm could provide some more
  interesting wins. There are also other places where we could choose to
  create large folios and currently do not, such as writes that are
  larger than PAGE_SIZE.

  I'd like to thank all my reviewers who've offered review/ack tags:
  Christoph Hellwig, David Howells, Jan Kara, Jeff Layton, Johannes
  Weiner, Kirill A. Shutemov, Michal Hocko, Mike Rapoport, Vlastimil
  Babka, William Kucharski, Yu Zhao and Zi Yan.

  I'd also like to thank those who gave feedback I incorporated but
  haven't offered up review tags for this part of the series: Nick
  Piggin, Mel Gorman, Ming Lei, Darrick Wong, Ted Ts'o, John Hubbard,
  Hugh Dickins, and probably a few others who I forget"

* tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache: (90 commits)
  mm/writeback: Add folio_write_one
  mm/filemap: Add FGP_STABLE
  mm/filemap: Add filemap_get_folio
  mm/filemap: Convert mapping_get_entry to return a folio
  mm/filemap: Add filemap_add_folio()
  mm/filemap: Add filemap_alloc_folio
  mm/page_alloc: Add folio allocation functions
  mm/lru: Add folio_add_lru()
  mm/lru: Convert __pagevec_lru_add_fn to take a folio
  mm: Add folio_evictable()
  mm/workingset: Convert workingset_refault() to take a folio
  mm/filemap: Add readahead_folio()
  mm/filemap: Add folio_mkwrite_check_truncate()
  mm/filemap: Add i_blocks_per_folio()
  mm/writeback: Add folio_redirty_for_writepage()
  mm/writeback: Add folio_account_redirty()
  mm/writeback: Add folio_clear_dirty_for_io()
  mm/writeback: Add folio_cancel_dirty()
  mm/writeback: Add folio_account_cleaned()
  mm/writeback: Add filemap_dirty_folio()
  ...

1 files changed, 194 insertions, 73 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index fbfd3fad48f2..d8623d6e1141 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -143,6 +143,8 @@ enum pageflags {
 #endif
 	__NR_PAGEFLAGS,
 
+	PG_readahead = PG_reclaim,
+
 	/* Filesystems */
 	PG_checked = PG_owner_priv_1,
 
@@ -202,6 +204,34 @@ static inline unsigned long _compound_head(const struct page *page)
 
 #define compound_head(page)	((typeof(page))_compound_head(page))
 
+/**
+ * page_folio - Converts from page to folio.
+ * @p: The page.
+ *
+ * Every page is part of a folio.  This function cannot be called on a
+ * NULL pointer.
+ *
+ * Context: No reference, nor lock is required on @page.  If the caller
+ * does not hold a reference, this call may race with a folio split, so
+ * it should re-check the folio still contains this page after gaining
+ * a reference on the folio.
+ * Return: The folio which contains this page.
+ */
+#define page_folio(p)		(_Generic((p),				\
+	const struct page *:	(const struct folio *)_compound_head(p), \
+	struct page *:		(struct folio *)_compound_head(p)))
+
+/**
+ * folio_page - Return a page from a folio.
+ * @folio: The folio.
+ * @n: The page number to return.
+ *
+ * @n is relative to the start of the folio.  This function does not
+ * check that the page number lies within @folio; the caller is presumed
+ * to have a reference to the page.
+ */
+#define folio_page(folio, n)	nth_page(&(folio)->page, n)
+
 static __always_inline int PageTail(struct page *page)
 {
 	return READ_ONCE(page->compound_head) & 1;
@@ -226,6 +256,15 @@ static inline void page_init_poison(struct page *page, size_t size)
 }
 #endif
 
+static unsigned long *folio_flags(struct folio *folio, unsigned n)
+{
+	struct page *page = &folio->page;
+
+	VM_BUG_ON_PGFLAGS(PageTail(page), page);
+	VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
+	return &page[n].flags;
+}
+
 /*
  * Page flags policies wrt compound pages
  *
@@ -270,36 +309,64 @@ static inline void page_init_poison(struct page *page, size_t size)
 		VM_BUG_ON_PGFLAGS(!PageHead(page), page);		\
 		PF_POISONED_CHECK(&page[1]); })
 
+/* Which page is the flag stored in */
+#define FOLIO_PF_ANY		0
+#define FOLIO_PF_HEAD		0
+#define FOLIO_PF_ONLY_HEAD	0
+#define FOLIO_PF_NO_TAIL	0
+#define FOLIO_PF_NO_COMPOUND	0
+#define FOLIO_PF_SECOND		1
+
 /*
  * Macros to create function definitions for page flags
  */
 #define TESTPAGEFLAG(uname, lname, policy)				\
+static __always_inline bool folio_test_##lname(struct folio *folio)	\
+{ return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); }	\
 static __always_inline int Page##uname(struct page *page)		\
-	{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
+{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
 
 #define SETPAGEFLAG(uname, lname, policy)				\
+static __always_inline							\
+void folio_set_##lname(struct folio *folio)				\
+{ set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); }		\
 static __always_inline void SetPage##uname(struct page *page)		\
-	{ set_bit(PG_##lname, &policy(page, 1)->flags); }
+{ set_bit(PG_##lname, &policy(page, 1)->flags); }
 
 #define CLEARPAGEFLAG(uname, lname, policy)				\
+static __always_inline							\
+void folio_clear_##lname(struct folio *folio)				\
+{ clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); }		\
 static __always_inline void ClearPage##uname(struct page *page)		\
-	{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
+{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
 
 #define __SETPAGEFLAG(uname, lname, policy)				\
+static __always_inline							\
+void __folio_set_##lname(struct folio *folio)				\
+{ __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); }		\
 static __always_inline void __SetPage##uname(struct page *page)		\
-	{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
+{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
 
 #define __CLEARPAGEFLAG(uname, lname, policy)				\
+static __always_inline							\
+void __folio_clear_##lname(struct folio *folio)				\
+{ __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); }	\
 static __always_inline void __ClearPage##uname(struct page *page)	\
-	{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
+{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
 
 #define TESTSETFLAG(uname, lname, policy)				\
+static __always_inline							\
+bool folio_test_set_##lname(struct folio *folio)			\
+{ return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
 static __always_inline int TestSetPage##uname(struct page *page)	\
-	{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
+{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
 
 #define TESTCLEARFLAG(uname, lname, policy)				\
+static __always_inline							\
+bool folio_test_clear_##lname(struct folio *folio)			\
+{ return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
 static __always_inline int TestClearPage##uname(struct page *page)	\
-	{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
+{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
 
 #define PAGEFLAG(uname, lname, policy)					\
 	TESTPAGEFLAG(uname, lname, policy)				\
@@ -315,29 +382,37 @@ static __always_inline int TestClearPage##uname(struct page *page)	\
 	TESTSETFLAG(uname, lname, policy)				\
 	TESTCLEARFLAG(uname, lname, policy)
 
-#define TESTPAGEFLAG_FALSE(uname)					\
+#define TESTPAGEFLAG_FALSE(uname, lname)				\
+static inline bool folio_test_##lname(const struct folio *folio) { return 0; } \
 static inline int Page##uname(const struct page *page) { return 0; }
 
-#define SETPAGEFLAG_NOOP(uname)						\
+#define SETPAGEFLAG_NOOP(uname, lname)					\
+static inline void folio_set_##lname(struct folio *folio) { }		\
 static inline void SetPage##uname(struct page *page) {  }
 
-#define CLEARPAGEFLAG_NOOP(uname)					\
+#define CLEARPAGEFLAG_NOOP(uname, lname)				\
+static inline void folio_clear_##lname(struct folio *folio) { }		\
 static inline void ClearPage##uname(struct page *page) {  }
 
-#define __CLEARPAGEFLAG_NOOP(uname)					\
+#define __CLEARPAGEFLAG_NOOP(uname, lname)				\
+static inline void __folio_clear_##lname(struct folio *folio) { }	\
 static inline void __ClearPage##uname(struct page *page) {  }
 
-#define TESTSETFLAG_FALSE(uname)					\
+#define TESTSETFLAG_FALSE(uname, lname)					\
+static inline bool folio_test_set_##lname(struct folio *folio)		\
+{ return 0; }								\
 static inline int TestSetPage##uname(struct page *page) { return 0; }
 
-#define TESTCLEARFLAG_FALSE(uname)					\
+#define TESTCLEARFLAG_FALSE(uname, lname)				\
+static inline bool folio_test_clear_##lname(struct folio *folio)	\
+{ return 0; }								\
 static inline int TestClearPage##uname(struct page *page) { return 0; }
 
-#define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)			\
-	SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
+#define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname)	\
+	SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
 
-#define TESTSCFLAG_FALSE(uname)						\
-	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
+#define TESTSCFLAG_FALSE(uname, lname)					\
+	TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
 
 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
@@ -393,8 +468,8 @@ PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
 	TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
-PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
-	TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
+PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
+	TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
 
 #ifdef CONFIG_HIGHMEM
 /*
@@ -403,22 +478,25 @@ PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
  */
 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
 #else
-PAGEFLAG_FALSE(HighMem)
+PAGEFLAG_FALSE(HighMem, highmem)
 #endif
 
 #ifdef CONFIG_SWAP
-static __always_inline int PageSwapCache(struct page *page)
+static __always_inline bool folio_test_swapcache(struct folio *folio)
 {
-#ifdef CONFIG_THP_SWAP
-	page = compound_head(page);
-#endif
-	return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
+	return folio_test_swapbacked(folio) &&
+			test_bit(PG_swapcache, folio_flags(folio, 0));
+}
 
+static __always_inline bool PageSwapCache(struct page *page)
+{
+	return folio_test_swapcache(page_folio(page));
 }
+
 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
 #else
-PAGEFLAG_FALSE(SwapCache)
+PAGEFLAG_FALSE(SwapCache, swapcache)
 #endif
 
 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
@@ -430,14 +508,14 @@ PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 	__CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 	TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
 #else
-PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
-	TESTSCFLAG_FALSE(Mlocked)
+PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
+	TESTSCFLAG_FALSE(Mlocked, mlocked)
 #endif
 
 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
 #else
-PAGEFLAG_FALSE(Uncached)
+PAGEFLAG_FALSE(Uncached, uncached)
 #endif
 
 #ifdef CONFIG_MEMORY_FAILURE
@@ -446,7 +524,7 @@ TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 #define __PG_HWPOISON (1UL << PG_hwpoison)
 extern bool take_page_off_buddy(struct page *page);
 #else
-PAGEFLAG_FALSE(HWPoison)
+PAGEFLAG_FALSE(HWPoison, hwpoison)
 #define __PG_HWPOISON 0
 #endif
 
@@ -460,7 +538,7 @@ PAGEFLAG(Idle, idle, PF_ANY)
 #ifdef CONFIG_KASAN_HW_TAGS
 PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
 #else
-PAGEFLAG_FALSE(SkipKASanPoison)
+PAGEFLAG_FALSE(SkipKASanPoison, skip_kasan_poison)
 #endif
 
 /*
@@ -498,10 +576,14 @@ static __always_inline int PageMappingFlags(struct page *page)
 	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
 }
 
-static __always_inline int PageAnon(struct page *page)
+static __always_inline bool folio_test_anon(struct folio *folio)
 {
-	page = compound_head(page);
-	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+	return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
+}
+
+static __always_inline bool PageAnon(struct page *page)
+{
+	return folio_test_anon(page_folio(page));
 }
 
 static __always_inline int __PageMovable(struct page *page)
@@ -517,30 +599,32 @@ static __always_inline int __PageMovable(struct page *page)
  * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
  * anon_vma, but to that page's node of the stable tree.
  */
-static __always_inline int PageKsm(struct page *page)
+static __always_inline bool folio_test_ksm(struct folio *folio)
 {
-	page = compound_head(page);
-	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
+	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
 				PAGE_MAPPING_KSM;
 }
+
+static __always_inline bool PageKsm(struct page *page)
+{
+	return folio_test_ksm(page_folio(page));
+}
 #else
-TESTPAGEFLAG_FALSE(Ksm)
+TESTPAGEFLAG_FALSE(Ksm, ksm)
 #endif
 
 u64 stable_page_flags(struct page *page);
 
-static inline int PageUptodate(struct page *page)
+static inline bool folio_test_uptodate(struct folio *folio)
 {
-	int ret;
-	page = compound_head(page);
-	ret = test_bit(PG_uptodate, &(page)->flags);
+	bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
 	/*
-	 * Must ensure that the data we read out of the page is loaded
-	 * _after_ we've loaded page->flags to check for PageUptodate.
-	 * We can skip the barrier if the page is not uptodate, because
+	 * Must ensure that the data we read out of the folio is loaded
+	 * _after_ we've loaded folio->flags to check the uptodate bit.
+	 * We can skip the barrier if the folio is not uptodate, because
 	 * we wouldn't be reading anything from it.
 	 *
-	 * See SetPageUptodate() for the other side of the story.
+	 * See folio_mark_uptodate() for the other side of the story.
 	 */
 	if (ret)
 		smp_rmb();
@@ -548,47 +632,71 @@ static inline int PageUptodate(struct page *page)
 	return ret;
 }
 
-static __always_inline void __SetPageUptodate(struct page *page)
+static inline int PageUptodate(struct page *page)
+{
+	return folio_test_uptodate(page_folio(page));
+}
+
+static __always_inline void __folio_mark_uptodate(struct folio *folio)
 {
-	VM_BUG_ON_PAGE(PageTail(page), page);
 	smp_wmb();
-	__set_bit(PG_uptodate, &page->flags);
+	__set_bit(PG_uptodate, folio_flags(folio, 0));
 }
 
-static __always_inline void SetPageUptodate(struct page *page)
+static __always_inline void folio_mark_uptodate(struct folio *folio)
 {
-	VM_BUG_ON_PAGE(PageTail(page), page);
 	/*
 	 * Memory barrier must be issued before setting the PG_uptodate bit,
-	 * so that all previous stores issued in order to bring the page
-	 * uptodate are actually visible before PageUptodate becomes true.
+	 * so that all previous stores issued in order to bring the folio
+	 * uptodate are actually visible before folio_test_uptodate becomes true.
 	 */
 	smp_wmb();
-	set_bit(PG_uptodate, &page->flags);
+	set_bit(PG_uptodate, folio_flags(folio, 0));
+}
+
+static __always_inline void __SetPageUptodate(struct page *page)
+{
+	__folio_mark_uptodate((struct folio *)page);
+}
+
+static __always_inline void SetPageUptodate(struct page *page)
+{
+	folio_mark_uptodate((struct folio *)page);
 }
 
 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
 
-int test_clear_page_writeback(struct page *page);
-int __test_set_page_writeback(struct page *page, bool keep_write);
+bool __folio_start_writeback(struct folio *folio, bool keep_write);
+bool set_page_writeback(struct page *page);
 
-#define test_set_page_writeback(page)			\
-	__test_set_page_writeback(page, false)
-#define test_set_page_writeback_keepwrite(page)	\
-	__test_set_page_writeback(page, true)
+#define folio_start_writeback(folio)			\
+	__folio_start_writeback(folio, false)
+#define folio_start_writeback_keepwrite(folio)	\
+	__folio_start_writeback(folio, true)
 
-static inline void set_page_writeback(struct page *page)
+static inline void set_page_writeback_keepwrite(struct page *page)
 {
-	test_set_page_writeback(page);
+	folio_start_writeback_keepwrite(page_folio(page));
 }
 
-static inline void set_page_writeback_keepwrite(struct page *page)
+static inline bool test_set_page_writeback(struct page *page)
 {
-	test_set_page_writeback_keepwrite(page);
+	return set_page_writeback(page);
 }
 
 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
 
+/* Whether there are one or multiple pages in a folio */
+static inline bool folio_test_single(struct folio *folio)
+{
+	return !folio_test_head(folio);
+}
+
+static inline bool folio_test_multi(struct folio *folio)
+{
+	return folio_test_head(folio);
+}
+
 static __always_inline void set_compound_head(struct page *page, struct page *head)
 {
 	WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
@@ -612,12 +720,15 @@ static inline void ClearPageCompound(struct page *page)
 #ifdef CONFIG_HUGETLB_PAGE
 int PageHuge(struct page *page);
 int PageHeadHuge(struct page *page);
+static inline bool folio_test_hugetlb(struct folio *folio)
+{
+	return PageHeadHuge(&folio->page);
+}
 #else
-TESTPAGEFLAG_FALSE(Huge)
-TESTPAGEFLAG_FALSE(HeadHuge)
+TESTPAGEFLAG_FALSE(Huge, hugetlb)
+TESTPAGEFLAG_FALSE(HeadHuge, headhuge)
 #endif
 
-
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 /*
  * PageHuge() only returns true for hugetlbfs pages, but not for
@@ -633,6 +744,11 @@ static inline int PageTransHuge(struct page *page)
 	return PageHead(page);
 }
 
+static inline bool folio_test_transhuge(struct folio *folio)
+{
+	return folio_test_head(folio);
+}
+
 /*
  * PageTransCompound returns true for both transparent huge pages
  * and hugetlbfs pages, so it should only be called when it's known
@@ -669,12 +785,12 @@ static inline int PageTransTail(struct page *page)
 PAGEFLAG(DoubleMap, double_map, PF_SECOND)
 	TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
 #else
-TESTPAGEFLAG_FALSE(TransHuge)
-TESTPAGEFLAG_FALSE(TransCompound)
-TESTPAGEFLAG_FALSE(TransCompoundMap)
-TESTPAGEFLAG_FALSE(TransTail)
-PAGEFLAG_FALSE(DoubleMap)
-	TESTSCFLAG_FALSE(DoubleMap)
+TESTPAGEFLAG_FALSE(TransHuge, transhuge)
+TESTPAGEFLAG_FALSE(TransCompound, transcompound)
+TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
+TESTPAGEFLAG_FALSE(TransTail, transtail)
+PAGEFLAG_FALSE(DoubleMap, double_map)
+	TESTSCFLAG_FALSE(DoubleMap, double_map)
 #endif
 
 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
@@ -872,6 +988,11 @@ static inline int page_has_private(struct page *page)
 	return !!(page->flags & PAGE_FLAGS_PRIVATE);
 }
 
+static inline bool folio_has_private(struct folio *folio)
+{
+	return page_has_private(&folio->page);
+}
+
 #undef PF_ANY
 #undef PF_HEAD
 #undef PF_ONLY_HEAD