xref: /openbmc/linux/include/linux/pagevec.h (revision 1e0877d5) 
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 
17 struct 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  */
28 struct 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  */
folio_batch_init(struct folio_batch * fbatch)40 static inline void folio_batch_init(struct folio_batch *fbatch)
41 {
42 	fbatch->nr = 0;
43 	fbatch->percpu_pvec_drained = false;
44 }
45 
folio_batch_reinit(struct folio_batch * fbatch)46 static inline void folio_batch_reinit(struct folio_batch *fbatch)
47 {
48 	fbatch->nr = 0;
49 }
50 
folio_batch_count(struct folio_batch * fbatch)51 static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
52 {
53 	return fbatch->nr;
54 }
55 
folio_batch_space(struct folio_batch * fbatch)56 static 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  */
folio_batch_add(struct folio_batch * fbatch,struct folio * folio)71 static 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 
78 void __folio_batch_release(struct folio_batch *pvec);
79 
folio_batch_release(struct folio_batch * fbatch)80 static inline void folio_batch_release(struct folio_batch *fbatch)
81 {
82 	if (folio_batch_count(fbatch))
83 		__folio_batch_release(fbatch);
84 }
85 
86 void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
87 #endif /* _LINUX_PAGEVEC_H */
88