xref: /linux-6.15/include/linux/pagevec.h (revision 7d80dd09) 
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 unsigned pagevec_lookup_range(struct pagevec *pvec,
30 			      struct address_space *mapping,
31 			      pgoff_t *start, pgoff_t end);
32 static inline unsigned pagevec_lookup(struct pagevec *pvec,
33 				      struct address_space *mapping,
34 				      pgoff_t *start)
35 {
36 	return pagevec_lookup_range(pvec, mapping, start, (pgoff_t)-1);
37 }
38 
39 unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
40 		struct address_space *mapping, pgoff_t *index, pgoff_t end,
41 		xa_mark_t tag);
42 static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
43 		struct address_space *mapping, pgoff_t *index, xa_mark_t tag)
44 {
45 	return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag);
46 }
47 
48 static inline void pagevec_init(struct pagevec *pvec)
49 {
50 	pvec->nr = 0;
51 	pvec->percpu_pvec_drained = false;
52 }
53 
54 static inline void pagevec_reinit(struct pagevec *pvec)
55 {
56 	pvec->nr = 0;
57 }
58 
59 static inline unsigned pagevec_count(struct pagevec *pvec)
60 {
61 	return pvec->nr;
62 }
63 
64 static inline unsigned pagevec_space(struct pagevec *pvec)
65 {
66 	return PAGEVEC_SIZE - pvec->nr;
67 }
68 
69 /*
70  * Add a page to a pagevec.  Returns the number of slots still available.
71  */
72 static inline unsigned pagevec_add(struct pagevec *pvec, struct page *page)
73 {
74 	pvec->pages[pvec->nr++] = page;
75 	return pagevec_space(pvec);
76 }
77 
78 static inline void pagevec_release(struct pagevec *pvec)
79 {
80 	if (pagevec_count(pvec))
81 		__pagevec_release(pvec);
82 }
83 
84 /**
85  * struct folio_batch - A collection of folios.
86  *
87  * The folio_batch is used to amortise the cost of retrieving and
88  * operating on a set of folios.  The order of folios in the batch may be
89  * significant (eg delete_from_page_cache_batch()).  Some users of the
90  * folio_batch store "exceptional" entries in it which can be removed
91  * by calling folio_batch_remove_exceptionals().
92  */
93 struct folio_batch {
94 	unsigned char nr;
95 	bool percpu_pvec_drained;
96 	struct folio *folios[PAGEVEC_SIZE];
97 };
98 
99 /* Layout must match pagevec */
100 static_assert(sizeof(struct pagevec) == sizeof(struct folio_batch));
101 static_assert(offsetof(struct pagevec, pages) ==
102 		offsetof(struct folio_batch, folios));
103 
104 /**
105  * folio_batch_init() - Initialise a batch of folios
106  * @fbatch: The folio batch.
107  *
108  * A freshly initialised folio_batch contains zero folios.
109  */
110 static inline void folio_batch_init(struct folio_batch *fbatch)
111 {
112 	fbatch->nr = 0;
113 	fbatch->percpu_pvec_drained = false;
114 }
115 
116 static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
117 {
118 	return fbatch->nr;
119 }
120 
121 static inline unsigned int fbatch_space(struct folio_batch *fbatch)
122 {
123 	return PAGEVEC_SIZE - fbatch->nr;
124 }
125 
126 /**
127  * folio_batch_add() - Add a folio to a batch.
128  * @fbatch: The folio batch.
129  * @folio: The folio to add.
130  *
131  * The folio is added to the end of the batch.
132  * The batch must have previously been initialised using folio_batch_init().
133  *
134  * Return: The number of slots still available.
135  */
136 static inline unsigned folio_batch_add(struct folio_batch *fbatch,
137 		struct folio *folio)
138 {
139 	fbatch->folios[fbatch->nr++] = folio;
140 	return fbatch_space(fbatch);
141 }
142 
143 static inline void folio_batch_release(struct folio_batch *fbatch)
144 {
145 	pagevec_release((struct pagevec *)fbatch);
146 }
147 
148 void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
149 #endif /* _LINUX_PAGEVEC_H */
150