[PATCH v3 07/11] mm/sparse-vmemmap: move vmemmap optimization helpers to a public header

[Muchun Song <songmuchun@bytedance.com>]

The vmemmap optimization helpers currently live in mm/sparse.h,
which is an internal MM header. That works for MM code, but
prevents powerpc from using the same interfaces without including a
private header.

Move the declarations and inline helpers to
include/linux/vmemmap-optimization.h. This is a preparatory change for
powerpc, which has its own vmemmap optimization implementation and needs
to use the common vmemmap optimization interfaces from architecture code.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
---
v3:
- Update the subject and commit message to describe common vmemmap
  optimization helpers
- Collect Acked-by from Qi Zheng

v2:
- Fix missing header dependencies.
---
 MAINTAINERS                          |  1 +
 include/linux/vmemmap-optimization.h | 94 ++++++++++++++++++++++++++++
 mm/hugetlb.c                         |  2 +-
 mm/hugetlb_vmemmap.c                 |  2 +-
 mm/sparse.h                          | 76 +---------------------
 5 files changed, 98 insertions(+), 77 deletions(-)
 create mode 100644 include/linux/vmemmap-optimization.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 3ef018673b5e..e4412c3d8d45 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12096,6 +12096,7 @@ F:	Documentation/mm/hugetlbfs_reserv.rst
 F:	Documentation/mm/vmemmap_dedup.rst
 F:	fs/hugetlbfs/
 F:	include/linux/hugetlb.h
+F:	include/linux/vmemmap-optimization.h
 F:	include/trace/events/hugetlbfs.h
 F:	mm/hugetlb.c
 F:	mm/hugetlb_cgroup.c
diff --git a/include/linux/vmemmap-optimization.h b/include/linux/vmemmap-optimization.h
new file mode 100644
index 000000000000..2327929467f3
--- /dev/null
+++ b/include/linux/vmemmap-optimization.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * vmemmap-optimization.h
+ *
+ * Generic vmemmap optimization declarations.
+ *
+ * Author: Muchun Song <songmuchun@bytedance.com>
+ */
+#ifndef _LINUX_VMEMMAP_OPTIMIZATION_H
+#define _LINUX_VMEMMAP_OPTIMIZATION_H
+
+#include <linux/align.h>
+#include <linux/log2.h>
+#include <linux/mmdebug.h>
+#include <linux/mmzone.h>
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
+static inline unsigned int section_compound_order(const struct mem_section *section)
+{
+	return section->compound_page_order;
+}
+
+static inline void section_set_compound_order(struct mem_section *section,
+					      unsigned int order)
+{
+	VM_WARN_ON(section_compound_order(section) && order &&
+		   section_compound_order(section) != order);
+	section->compound_page_order = order;
+}
+
+static inline void section_set_compound_order_range(unsigned long pfn,
+		unsigned long nr_pages, unsigned int order)
+{
+	unsigned long section_nr = pfn_to_section_nr(pfn);
+
+	if (!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))
+		return;
+
+	for (unsigned long i = 0; i < nr_pages / PAGES_PER_SECTION; i++)
+		section_set_compound_order(__nr_to_section(section_nr + i), order);
+}
+
+static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
+{
+	return section_compound_order(__pfn_to_section(pfn));
+}
+#else
+static inline unsigned int section_compound_order(const struct mem_section *section)
+{
+	return 0;
+}
+
+static inline void section_set_compound_order(struct mem_section *section,
+					      unsigned int order)
+{
+}
+
+static inline void section_set_compound_order_range(unsigned long pfn,
+		unsigned long nr_pages, unsigned int order)
+{
+}
+
+static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
+{
+	return 0;
+}
+#endif /* CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION */
+
+static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
+{
+	const unsigned int order = pfn_to_section_compound_order(pfn);
+	const unsigned long nr_pages = 1UL << order;
+
+	if (!is_power_of_2(sizeof(struct page)))
+		return false;
+
+	return (pfn & (nr_pages - 1)) >= VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES;
+}
+
+static inline bool vmemmap_optimizable_order(unsigned int order)
+{
+	if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
+		return false;
+
+	if (!is_power_of_2(sizeof(struct page)))
+		return false;
+
+	return order >= VMEMMAP_OPTIMIZATION_MIN_ORDER;
+}
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+struct page *vmemmap_shared_tail_page(unsigned int order, struct zone *zone);
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+#endif /* _LINUX_VMEMMAP_OPTIMIZATION_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0d101ef934fc..7af55e1544e9 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -38,6 +38,7 @@
 #include <linux/mm_inline.h>
 #include <linux/padata.h>
 #include <linux/pgalloc.h>
+#include <linux/vmemmap-optimization.h>
 
 #include <asm/page.h>
 #include <asm/tlb.h>
@@ -52,7 +53,6 @@
 #include "hugetlb_cma.h"
 #include "hugetlb_internal.h"
 #include "mm_init.h"
-#include "sparse.h"
 #include <linux/page-isolation.h>
 
 #define HUGE_BOOTMEM_ZONES_VALID	BIT(0)
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 5ddf06b83c96..a27f46fffb54 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -15,10 +15,10 @@
 #include <linux/mmdebug.h>
 #include <linux/pagewalk.h>
 #include <linux/pgalloc.h>
+#include <linux/vmemmap-optimization.h>
 
 #include <asm/tlbflush.h>
 #include "hugetlb_vmemmap.h"
-#include "sparse.h"
 #include "internal.h"
 
 /**
diff --git a/mm/sparse.h b/mm/sparse.h
index a250bea4088e..a5111087ee3a 100644
--- a/mm/sparse.h
+++ b/mm/sparse.h
@@ -9,80 +9,7 @@
 #define __MM_SPARSE_H
 
 #include <linux/mmzone.h>
-
-#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
-static inline unsigned int section_compound_order(const struct mem_section *section)
-{
-	return section->compound_page_order;
-}
-
-static inline void section_set_compound_order(struct mem_section *section,
-					      unsigned int order)
-{
-	VM_WARN_ON(section_compound_order(section) && order &&
-		   section_compound_order(section) != order);
-	section->compound_page_order = order;
-}
-
-static inline void section_set_compound_order_range(unsigned long pfn,
-		unsigned long nr_pages, unsigned int order)
-{
-	unsigned long section_nr = pfn_to_section_nr(pfn);
-
-	if (!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))
-		return;
-
-	for (unsigned long i = 0; i < nr_pages / PAGES_PER_SECTION; i++)
-		section_set_compound_order(__nr_to_section(section_nr + i), order);
-}
-
-static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
-{
-	return section_compound_order(__pfn_to_section(pfn));
-}
-#else
-static inline unsigned int section_compound_order(const struct mem_section *section)
-{
-	return 0;
-}
-
-static inline void section_set_compound_order(struct mem_section *section,
-					      unsigned int order)
-{
-}
-
-static inline void section_set_compound_order_range(unsigned long pfn,
-		unsigned long nr_pages, unsigned int order)
-{
-}
-
-static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
-{
-	return 0;
-}
-#endif
-
-static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
-{
-	const unsigned int order = pfn_to_section_compound_order(pfn);
-	const unsigned long nr_pages = 1UL << order;
-
-	if (!is_power_of_2(sizeof(struct page)))
-		return false;
-
-	return (pfn & (nr_pages - 1)) >= VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES;
-}
-
-static inline bool vmemmap_optimizable_order(unsigned int order)
-{
-	if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
-		return false;
-
-	if (!is_power_of_2(sizeof(struct page)))
-		return false;
-
-	return order >= VMEMMAP_OPTIMIZATION_MIN_ORDER;
-}
+#include <linux/vmemmap-optimization.h>
 
 /*
  * mm/sparse.c
@@ -142,7 +69,6 @@ static inline void sparse_sections_init(void) {}
  * mm/sparse-vmemmap.c
  */
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
-struct page *vmemmap_shared_tail_page(unsigned int order, struct zone *zone);
 void sparse_init_subsection_map(void);
 int section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages,
 		struct vmem_altmap *altmap, struct dev_pagemap *pgmap);
-- 
2.54.0