1 /*
2  * Macros for manipulating and testing flags related to a
3  * pageblock_nr_pages number of pages.
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation version 2 of the License
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17  *
18  * Copyright (C) IBM Corporation, 2006
19  *
20  * Original author, Mel Gorman
21  * Major cleanups and reduction of bit operations, Andy Whitcroft
22  */
23 #ifndef PAGEBLOCK_FLAGS_H
24 #define PAGEBLOCK_FLAGS_H
25 
26 #include <linux/types.h>
27 
28 /* Bit indices that affect a whole block of pages */
29 enum pageblock_bits {
30 	PB_migrate,
31 	PB_migrate_end = PB_migrate + 3 - 1,
32 			/* 3 bits required for migrate types */
33 	PB_migrate_skip,/* If set the block is skipped by compaction */
34 
35 	/*
36 	 * Assume the bits will always align on a word. If this assumption
37 	 * changes then get/set pageblock needs updating.
38 	 */
39 	NR_PAGEBLOCK_BITS
40 };
41 
42 #ifdef CONFIG_HUGETLB_PAGE
43 
44 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
45 
46 /* Huge page sizes are variable */
47 extern unsigned int pageblock_order;
48 
49 #else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
50 
51 /* Huge pages are a constant size */
52 #define pageblock_order		HUGETLB_PAGE_ORDER
53 
54 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
55 
56 #else /* CONFIG_HUGETLB_PAGE */
57 
58 /* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
59 #define pageblock_order		(MAX_ORDER-1)
60 
61 #endif /* CONFIG_HUGETLB_PAGE */
62 
63 #define pageblock_nr_pages	(1UL << pageblock_order)
64 
65 /* Forward declaration */
66 struct page;
67 
68 unsigned long get_pfnblock_flags_mask(struct page *page,
69 				unsigned long pfn,
70 				unsigned long end_bitidx,
71 				unsigned long mask);
72 
73 void set_pfnblock_flags_mask(struct page *page,
74 				unsigned long flags,
75 				unsigned long pfn,
76 				unsigned long end_bitidx,
77 				unsigned long mask);
78 
79 /* Declarations for getting and setting flags. See mm/page_alloc.c */
80 #define get_pageblock_flags_group(page, start_bitidx, end_bitidx) \
81 	get_pfnblock_flags_mask(page, page_to_pfn(page),		\
82 			end_bitidx,					\
83 			(1 << (end_bitidx - start_bitidx + 1)) - 1)
84 #define set_pageblock_flags_group(page, flags, start_bitidx, end_bitidx) \
85 	set_pfnblock_flags_mask(page, flags, page_to_pfn(page),		\
86 			end_bitidx,					\
87 			(1 << (end_bitidx - start_bitidx + 1)) - 1)
88 
89 #ifdef CONFIG_COMPACTION
90 #define get_pageblock_skip(page) \
91 			get_pageblock_flags_group(page, PB_migrate_skip,     \
92 							PB_migrate_skip)
93 #define clear_pageblock_skip(page) \
94 			set_pageblock_flags_group(page, 0, PB_migrate_skip,  \
95 							PB_migrate_skip)
96 #define set_pageblock_skip(page) \
97 			set_pageblock_flags_group(page, 1, PB_migrate_skip,  \
98 							PB_migrate_skip)
99 #else
get_pageblock_skip(struct page * page)100 static inline bool get_pageblock_skip(struct page *page)
101 {
102 	return false;
103 }
clear_pageblock_skip(struct page * page)104 static inline void clear_pageblock_skip(struct page *page)
105 {
106 }
set_pageblock_skip(struct page * page)107 static inline void set_pageblock_skip(struct page *page)
108 {
109 }
110 #endif /* CONFIG_COMPACTION */
111 
112 #endif	/* PAGEBLOCK_FLAGS_H */
113