[PATCH 6/8] mm: Constify get_pfnblock_flags_mask and get_pfnblock_migratetype

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

The struct page is not modified by these routines, so it can be marked
const.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 include/linux/pageblock-flags.h |  2 +-
 mm/page_alloc.c                 | 13 +++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index fff52ad370c1..973fd731a520 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -54,7 +54,7 @@ extern unsigned int pageblock_order;
 /* Forward declaration */
 struct page;
 
-unsigned long get_pfnblock_flags_mask(struct page *page,
+unsigned long get_pfnblock_flags_mask(const struct page *page,
 				unsigned long pfn,
 				unsigned long mask);
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f23702e7c564..5a1e5b624594 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -474,7 +474,7 @@ static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 #endif
 
 /* Return a pointer to the bitmap storing bits affecting a block of pages */
-static inline unsigned long *get_pageblock_bitmap(struct page *page,
+static inline unsigned long *get_pageblock_bitmap(const struct page *page,
 							unsigned long pfn)
 {
 #ifdef CONFIG_SPARSEMEM
@@ -484,7 +484,7 @@ static inline unsigned long *get_pageblock_bitmap(struct page *page,
 #endif /* CONFIG_SPARSEMEM */
 }
 
-static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
+static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
 {
 #ifdef CONFIG_SPARSEMEM
 	pfn &= (PAGES_PER_SECTION-1);
@@ -495,7 +495,7 @@ static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
 }
 
 static __always_inline
-unsigned long __get_pfnblock_flags_mask(struct page *page,
+unsigned long __get_pfnblock_flags_mask(const struct page *page,
 					unsigned long pfn,
 					unsigned long mask)
 {
@@ -520,13 +520,14 @@ unsigned long __get_pfnblock_flags_mask(struct page *page,
  *
  * Return: pageblock_bits flags
  */
-unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
-					unsigned long mask)
+unsigned long get_pfnblock_flags_mask(const struct page *page,
+					unsigned long pfn, unsigned long mask)
 {
 	return __get_pfnblock_flags_mask(page, pfn, mask);
 }
 
-static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
+static __always_inline int get_pfnblock_migratetype(const struct page *page,
+					unsigned long pfn)
 {
 	return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
 }
-- 
2.30.2