xref: /openbmc/linux/include/linux/pagevec.h (revision 6b342707) 
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * include/linux/pagevec.h
4  *
5  * In many places it is efficient to batch an operation up against multiple
6  * pages.  A pagevec is a multipage container which is used for that.
7  */
8 
9 #ifndef _LINUX_PAGEVEC_H
10 #define _LINUX_PAGEVEC_H
11 
12 #include <linux/xarray.h>
13 
14 /* 15 pointers + header align the pagevec structure to a power of two */
15 #define PAGEVEC_SIZE	15
16 
17 struct page;
18 struct folio;
19 struct address_space;
20 
21 /* Layout must match folio_batch */
22 struct pagevec {
23 	unsigned char nr;
24 	bool percpu_pvec_drained;
25 	struct page *pages[PAGEVEC_SIZE];
26 };
27 
28 void __pagevec_release(struct pagevec *pvec);
29 void __pagevec_lru_add(struct pagevec *pvec);
30 unsigned pagevec_lookup_range(struct pagevec *pvec,
31 			      struct address_space *mapping,
32 			      pgoff_t *start, pgoff_t end);
33 static inline unsigned pagevec_lookup(struct pagevec *pvec,
34 				      struct address_space *mapping,
35 				      pgoff_t *start)
36 {
37 	return pagevec_lookup_range(pvec, mapping, start, (pgoff_t)-1);
38 }
39 
40 unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
41 		struct address_space *mapping, pgoff_t *index, pgoff_t end,
42 		xa_mark_t tag);
43 static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
44 		struct address_space *mapping, pgoff_t *index, xa_mark_t tag)
45 {
46 	return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag);
47 }
48 
49 static inline void pagevec_init(struct pagevec *pvec)
50 {
51 	pvec->nr = 0;
52 	pvec->percpu_pvec_drained = false;
53 }
54 
55 static inline void pagevec_reinit(struct pagevec *pvec)
56 {
57 	pvec->nr = 0;
58 }
59 
60 static inline unsigned pagevec_count(struct pagevec *pvec)
61 {
62 	return pvec->nr;
63 }
64 
65 static inline unsigned pagevec_space(struct pagevec *pvec)
66 {
67 	return PAGEVEC_SIZE - pvec->nr;
68 }
69 
70 /*
71  * Add a page to a pagevec.  Returns the number of slots still available.
72  */
73 static inline unsigned pagevec_add(struct pagevec *pvec, struct page *page)
74 {
75 	pvec->pages[pvec->nr++] = page;
76 	return pagevec_space(pvec);
77 }
78 
79 static inline void pagevec_release(struct pagevec *pvec)
80 {
81 	if (pagevec_count(pvec))
82 		__pagevec_release(pvec);
83 }
84 
85 /**
86  * struct folio_batch - A collection of folios.
87  *
88  * The folio_batch is used to amortise the cost of retrieving and
89  * operating on a set of folios.  The order of folios in the batch may be
90  * significant (eg delete_from_page_cache_batch()).  Some users of the
91  * folio_batch store "exceptional" entries in it which can be removed
92  * by calling folio_batch_remove_exceptionals().
93  */
94 struct folio_batch {
95 	unsigned char nr;
96 	bool percpu_pvec_drained;
97 	struct folio *folios[PAGEVEC_SIZE];
98 };
99 
100 /* Layout must match pagevec */
101 static_assert(sizeof(struct pagevec) == sizeof(struct folio_batch));
102 static_assert(offsetof(struct pagevec, pages) ==
103 		offsetof(struct folio_batch, folios));
104 
105 /**
106  * folio_batch_init() - Initialise a batch of folios
107  * @fbatch: The folio batch.
108  *
109  * A freshly initialised folio_batch contains zero folios.
110  */
111 static inline void folio_batch_init(struct folio_batch *fbatch)
112 {
113 	fbatch->nr = 0;
114 	fbatch->percpu_pvec_drained = false;
115 }
116 
117 static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
118 {
119 	return fbatch->nr;
120 }
121 
122 static inline unsigned int fbatch_space(struct folio_batch *fbatch)
123 {
124 	return PAGEVEC_SIZE - fbatch->nr;
125 }
126 
127 /**
128  * folio_batch_add() - Add a folio to a batch.
129  * @fbatch: The folio batch.
130  * @folio: The folio to add.
131  *
132  * The folio is added to the end of the batch.
133  * The batch must have previously been initialised using folio_batch_init().
134  *
135  * Return: The number of slots still available.
136  */
137 static inline unsigned folio_batch_add(struct folio_batch *fbatch,
138 		struct folio *folio)
139 {
140 	fbatch->folios[fbatch->nr++] = folio;
141 	return fbatch_space(fbatch);
142 }
143 
144 static inline void folio_batch_release(struct folio_batch *fbatch)
145 {
146 	pagevec_release((struct pagevec *)fbatch);
147 }
148 
149 void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
150 #endif /* _LINUX_PAGEVEC_H */
151