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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 * folios. A folio_batch is a container which is used for that.
7 */
8
9#ifndef _LINUX_PAGEVEC_H
10#define _LINUX_PAGEVEC_H
11
12#include <linux/types.h>
13
14/* 15 pointers + header align the folio_batch structure to a power of two */
15#define PAGEVEC_SIZE 15
16
17struct folio;
18
19/**
20 * struct folio_batch - A collection of folios.
21 *
22 * The folio_batch is used to amortise the cost of retrieving and
23 * operating on a set of folios. The order of folios in the batch may be
24 * significant (eg delete_from_page_cache_batch()). Some users of the
25 * folio_batch store "exceptional" entries in it which can be removed
26 * by calling folio_batch_remove_exceptionals().
27 */
28struct folio_batch {
29 unsigned char nr;
30 bool percpu_pvec_drained;
31 struct folio *folios[PAGEVEC_SIZE];
32};
33
34/**
35 * folio_batch_init() - Initialise a batch of folios
36 * @fbatch: The folio batch.
37 *
38 * A freshly initialised folio_batch contains zero folios.
39 */
40static inline void folio_batch_init(struct folio_batch *fbatch)
41{
42 fbatch->nr = 0;
43 fbatch->percpu_pvec_drained = false;
44}
45
46static inline void folio_batch_reinit(struct folio_batch *fbatch)
47{
48 fbatch->nr = 0;
49}
50
51static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
52{
53 return fbatch->nr;
54}
55
56static inline unsigned int folio_batch_space(struct folio_batch *fbatch)
57{
58 return PAGEVEC_SIZE - fbatch->nr;
59}
60
61/**
62 * folio_batch_add() - Add a folio to a batch.
63 * @fbatch: The folio batch.
64 * @folio: The folio to add.
65 *
66 * The folio is added to the end of the batch.
67 * The batch must have previously been initialised using folio_batch_init().
68 *
69 * Return: The number of slots still available.
70 */
71static inline unsigned folio_batch_add(struct folio_batch *fbatch,
72 struct folio *folio)
73{
74 fbatch->folios[fbatch->nr++] = folio;
75 return folio_batch_space(fbatch);
76}
77
78void __folio_batch_release(struct folio_batch *pvec);
79
80static inline void folio_batch_release(struct folio_batch *fbatch)
81{
82 if (folio_batch_count(fbatch))
83 __folio_batch_release(fbatch);
84}
85
86void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
87#endif /* _LINUX_PAGEVEC_H */