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/* 31 pointers + header align the folio_batch structure to a power of two */ 15#define PAGEVEC_SIZE 31 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 unsigned char i; 31 bool percpu_pvec_drained; 32 struct folio *folios[PAGEVEC_SIZE]; 33}; 34 35/** 36 * folio_batch_init() - Initialise a batch of folios 37 * @fbatch: The folio batch. 38 * 39 * A freshly initialised folio_batch contains zero folios. 40 */ 41static inline void folio_batch_init(struct folio_batch *fbatch) 42{ 43 fbatch->nr = 0; 44 fbatch->i = 0; 45 fbatch->percpu_pvec_drained = false; 46} 47 48static inline void folio_batch_reinit(struct folio_batch *fbatch) 49{ 50 fbatch->nr = 0; 51 fbatch->i = 0; 52} 53 54static inline unsigned int folio_batch_count(struct folio_batch *fbatch) 55{ 56 return fbatch->nr; 57} 58 59static inline unsigned int folio_batch_space(struct folio_batch *fbatch) 60{ 61 return PAGEVEC_SIZE - fbatch->nr; 62} 63 64/** 65 * folio_batch_add() - Add a folio to a batch. 66 * @fbatch: The folio batch. 67 * @folio: The folio to add. 68 * 69 * The folio is added to the end of the batch. 70 * The batch must have previously been initialised using folio_batch_init(). 71 * 72 * Return: The number of slots still available. 73 */ 74static inline unsigned folio_batch_add(struct folio_batch *fbatch, 75 struct folio *folio) 76{ 77 fbatch->folios[fbatch->nr++] = folio; 78 return folio_batch_space(fbatch); 79} 80 81/** 82 * folio_batch_next - Return the next folio to process. 83 * @fbatch: The folio batch being processed. 84 * 85 * Use this function to implement a queue of folios. 86 * 87 * Return: The next folio in the queue, or NULL if the queue is empty. 88 */ 89static inline struct folio *folio_batch_next(struct folio_batch *fbatch) 90{ 91 if (fbatch->i == fbatch->nr) 92 return NULL; 93 return fbatch->folios[fbatch->i++]; 94} 95 96void __folio_batch_release(struct folio_batch *pvec); 97 98static inline void folio_batch_release(struct folio_batch *fbatch) 99{ 100 if (folio_batch_count(fbatch)) 101 __folio_batch_release(fbatch); 102} 103 104void folio_batch_remove_exceptionals(struct folio_batch *fbatch); 105#endif /* _LINUX_PAGEVEC_H */ 106