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

Pull folio fixes from Matthew Wilcox:
 "In the course of preparing the folio changes for iomap for next merge
  window, we discovered some problems that would be nice to address now:

   - Renaming multi-page folios to large folios.

     mapping_multi_page_folio_support() is just a little too long, so we
     settled on mapping_large_folio_support(). That meant renaming, eg
     folio_test_multi() to folio_test_large().

     Rename AS_THP_SUPPORT to match

   - I hadn't included folio wrappers for zero_user_segments(), etc.
     Also, multi-page^W^W large folio support is now independent of
     CONFIG_TRANSPARENT_HUGEPAGE, so machines with HIGHMEM always need
     to fall back to the out-of-line zero_user_segments().

     Remove FS_THP_SUPPORT to match

   - The build bots finally got round to telling me that I missed a
     couple of architectures when adding flush_dcache_folio(). Christoph
     suggested that we just add linux/cacheflush.h and not rely on
     asm-generic/cacheflush.h"

* tag 'folio-5.16b' of git://git.infradead.org/users/willy/pagecache:
  mm: Add functions to zero portions of a folio
  fs: Rename AS_THP_SUPPORT and mapping_thp_support
  fs: Remove FS_THP_SUPPORT
  mm: Remove folio_test_single
  mm: Rename folio_test_multi to folio_test_large
  Add linux/cacheflush.h

6 files changed, 88 insertions, 24 deletions

diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h
index fedc0dfa4877..4f07afacbc23 100644
--- a/include/asm-generic/cacheflush.h
+++ b/include/asm-generic/cacheflush.h
@@ -50,13 +50,7 @@ static inline void flush_dcache_page(struct page *page)
 {
 }
 
-static inline void flush_dcache_folio(struct folio *folio) { }
 #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0
-#define ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
-#endif
-
-#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
-void flush_dcache_folio(struct folio *folio);
 #endif
 
 #ifndef flush_dcache_mmap_lock
diff --git a/include/linux/cacheflush.h b/include/linux/cacheflush.h
new file mode 100644
index 000000000000..fef8b607f97e
--- /dev/null
+++ b/include/linux/cacheflush.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CACHEFLUSH_H
+#define _LINUX_CACHEFLUSH_H
+
+#include <asm/cacheflush.h>
+
+#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
+#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
+void flush_dcache_folio(struct folio *folio);
+#endif
+#else
+static inline void flush_dcache_folio(struct folio *folio)
+{
+}
+#define ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO 0
+#endif /* ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE */
+
+#endif /* _LINUX_CACHEFLUSH_H */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1cb616fc1105..bbf812ce89a8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2518,7 +2518,6 @@ struct file_system_type {
 #define FS_USERNS_MOUNT		8	/* Can be mounted by userns root */
 #define FS_DISALLOW_NOTIFY_PERM	16	/* Disable fanotify permission events */
 #define FS_ALLOW_IDMAP         32      /* FS has been updated to handle vfs idmappings. */
-#define FS_THP_SUPPORT		8192	/* Remove once all fs converted */
 #define FS_RENAME_DOES_D_MOVE	32768	/* FS will handle d_move() during rename() internally. */
 	int (*init_fs_context)(struct fs_context *);
 	const struct fs_parameter_spec *parameters;
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 25aff0f2ed0b..39bb9b47fa9c 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -5,12 +5,11 @@
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/bug.h>
+#include <linux/cacheflush.h>
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
 
-#include <asm/cacheflush.h>
-
 #include "highmem-internal.h"
 
 /**
@@ -231,10 +230,10 @@ static inline void tag_clear_highpage(struct page *page)
  * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
  * If we pass in a head page, we can zero up to the size of the compound page.
  */
-#if defined(CONFIG_HIGHMEM) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+#ifdef CONFIG_HIGHMEM
 void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
 		unsigned start2, unsigned end2);
-#else /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
+#else
 static inline void zero_user_segments(struct page *page,
 		unsigned start1, unsigned end1,
 		unsigned start2, unsigned end2)
@@ -254,7 +253,7 @@ static inline void zero_user_segments(struct page *page,
 	for (i = 0; i < compound_nr(page); i++)
 		flush_dcache_page(page + i);
 }
-#endif /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
+#endif
 
 static inline void zero_user_segment(struct page *page,
 	unsigned start, unsigned end)
@@ -364,4 +363,42 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len)
 	kunmap_local(addr);
 }
 
+/**
+ * folio_zero_segments() - Zero two byte ranges in a folio.
+ * @folio: The folio to write to.
+ * @start1: The first byte to zero.
+ * @xend1: One more than the last byte in the first range.
+ * @start2: The first byte to zero in the second range.
+ * @xend2: One more than the last byte in the second range.
+ */
+static inline void folio_zero_segments(struct folio *folio,
+		size_t start1, size_t xend1, size_t start2, size_t xend2)
+{
+	zero_user_segments(&folio->page, start1, xend1, start2, xend2);
+}
+
+/**
+ * folio_zero_segment() - Zero a byte range in a folio.
+ * @folio: The folio to write to.
+ * @start: The first byte to zero.
+ * @xend: One more than the last byte to zero.
+ */
+static inline void folio_zero_segment(struct folio *folio,
+		size_t start, size_t xend)
+{
+	zero_user_segments(&folio->page, start, xend, 0, 0);
+}
+
+/**
+ * folio_zero_range() - Zero a byte range in a folio.
+ * @folio: The folio to write to.
+ * @start: The first byte to zero.
+ * @length: The number of bytes to zero.
+ */
+static inline void folio_zero_range(struct folio *folio,
+		size_t start, size_t length)
+{
+	zero_user_segments(&folio->page, start, start + length, 0, 0);
+}
+
 #endif /* _LINUX_HIGHMEM_H */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 52ec4b5e5615..b5f14d581113 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -686,13 +686,13 @@ static inline bool test_set_page_writeback(struct page *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)
+/**
+ * folio_test_large() - Does this folio contain more than one page?
+ * @folio: The folio to test.
+ *
+ * Return: True if the folio is larger than one page.
+ */
+static inline bool folio_test_large(struct folio *folio)
 {
 	return folio_test_head(folio);
 }
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 1a0c646eb6ff..605246452305 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -84,7 +84,7 @@ enum mapping_flags {
 	AS_EXITING	= 4, 	/* final truncate in progress */
 	/* writeback related tags are not used */
 	AS_NO_WRITEBACK_TAGS = 5,
-	AS_THP_SUPPORT = 6,	/* THPs supported */
+	AS_LARGE_FOLIO_SUPPORT = 6,
 };
 
 /**
@@ -176,9 +176,25 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
 	m->gfp_mask = mask;
 }
 
-static inline bool mapping_thp_support(struct address_space *mapping)
+/**
+ * mapping_set_large_folios() - Indicate the file supports large folios.
+ * @mapping: The file.
+ *
+ * The filesystem should call this function in its inode constructor to
+ * indicate that the VFS can use large folios to cache the contents of
+ * the file.
+ *
+ * Context: This should not be called while the inode is active as it
+ * is non-atomic.
+ */
+static inline void mapping_set_large_folios(struct address_space *mapping)
+{
+	__set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
+}
+
+static inline bool mapping_large_folio_support(struct address_space *mapping)
 {
-	return test_bit(AS_THP_SUPPORT, &mapping->flags);
+	return test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
 }
 
 static inline int filemap_nr_thps(struct address_space *mapping)
@@ -193,7 +209,7 @@ static inline int filemap_nr_thps(struct address_space *mapping)
 static inline void filemap_nr_thps_inc(struct address_space *mapping)
 {
 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
-	if (!mapping_thp_support(mapping))
+	if (!mapping_large_folio_support(mapping))
 		atomic_inc(&mapping->nr_thps);
 #else
 	WARN_ON_ONCE(1);
@@ -203,7 +219,7 @@ static inline void filemap_nr_thps_inc(struct address_space *mapping)
 static inline void filemap_nr_thps_dec(struct address_space *mapping)
 {
 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
-	if (!mapping_thp_support(mapping))
+	if (!mapping_large_folio_support(mapping))
 		atomic_dec(&mapping->nr_thps);
 #else
 	WARN_ON_ONCE(1);