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
17struct page;
18struct folio;
19struct address_space;
20
21/* Layout must match folio_batch */
22struct pagevec {
23 unsigned char nr;
24 bool percpu_pvec_drained;
25 struct page *pages[PAGEVEC_SIZE];
26};
27
28void __pagevec_release(struct pagevec *pvec);
29unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
30 struct address_space *mapping, pgoff_t *index, pgoff_t end,
31 xa_mark_t tag);
32static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
33 struct address_space *mapping, pgoff_t *index, xa_mark_t tag)
34{
35 return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag);
36}
37
38static inline void pagevec_init(struct pagevec *pvec)
39{
40 pvec->nr = 0;
41 pvec->percpu_pvec_drained = false;
42}
43
44static inline void pagevec_reinit(struct pagevec *pvec)
45{
46 pvec->nr = 0;
47}
48
49static inline unsigned pagevec_count(struct pagevec *pvec)
50{
51 return pvec->nr;
52}
53
54static inline unsigned pagevec_space(struct pagevec *pvec)
55{
56 return PAGEVEC_SIZE - pvec->nr;
57}
58
59/*
60 * Add a page to a pagevec. Returns the number of slots still available.
61 */
62static inline unsigned pagevec_add(struct pagevec *pvec, struct page *page)
63{
64 pvec->pages[pvec->nr++] = page;
65 return pagevec_space(pvec);
66}
67
68static inline void pagevec_release(struct pagevec *pvec)
69{
70 if (pagevec_count(pvec))
71 __pagevec_release(pvec);
72}
73
74/**
75 * struct folio_batch - A collection of folios.
76 *
77 * The folio_batch is used to amortise the cost of retrieving and
78 * operating on a set of folios. The order of folios in the batch may be
79 * significant (eg delete_from_page_cache_batch()). Some users of the
80 * folio_batch store "exceptional" entries in it which can be removed
81 * by calling folio_batch_remove_exceptionals().
82 */
83struct folio_batch {
84 unsigned char nr;
85 bool percpu_pvec_drained;
86 struct folio *folios[PAGEVEC_SIZE];
87};
88
89/* Layout must match pagevec */
90static_assert(sizeof(struct pagevec) == sizeof(struct folio_batch));
91static_assert(offsetof(struct pagevec, pages) ==
92 offsetof(struct folio_batch, folios));
93
94/**
95 * folio_batch_init() - Initialise a batch of folios
96 * @fbatch: The folio batch.
97 *
98 * A freshly initialised folio_batch contains zero folios.
99 */
100static inline void folio_batch_init(struct folio_batch *fbatch)
101{
102 fbatch->nr = 0;
103 fbatch->percpu_pvec_drained = false;
104}
105
106static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
107{
108 return fbatch->nr;
109}
110
111static inline unsigned int fbatch_space(struct folio_batch *fbatch)
112{
113 return PAGEVEC_SIZE - fbatch->nr;
114}
115
116/**
117 * folio_batch_add() - Add a folio to a batch.
118 * @fbatch: The folio batch.
119 * @folio: The folio to add.
120 *
121 * The folio is added to the end of the batch.
122 * The batch must have previously been initialised using folio_batch_init().
123 *
124 * Return: The number of slots still available.
125 */
126static inline unsigned folio_batch_add(struct folio_batch *fbatch,
127 struct folio *folio)
128{
129 fbatch->folios[fbatch->nr++] = folio;
130 return fbatch_space(fbatch);
131}
132
133static inline void folio_batch_release(struct folio_batch *fbatch)
134{
135 pagevec_release((struct pagevec *)fbatch);
136}
137
138void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
139#endif /* _LINUX_PAGEVEC_H */
140

source code of linux/include/linux/pagevec.h