1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Copyright (C) 2018 HUAWEI, Inc. 4 * https://www.huawei.com/ 5 * Created by Gao Xiang <gaoxiang25@huawei.com> 6 */ 7#ifndef __EROFS_FS_ZPVEC_H 8#define __EROFS_FS_ZPVEC_H 9 10#include "tagptr.h" 11 12/* page type in pagevec for decompress subsystem */ 13enum z_erofs_page_type { 14 /* including Z_EROFS_VLE_PAGE_TAIL_EXCLUSIVE */ 15 Z_EROFS_PAGE_TYPE_EXCLUSIVE, 16 17 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED, 18 19 Z_EROFS_VLE_PAGE_TYPE_HEAD, 20 Z_EROFS_VLE_PAGE_TYPE_MAX 21}; 22 23extern void __compiletime_error("Z_EROFS_PAGE_TYPE_EXCLUSIVE != 0") 24 __bad_page_type_exclusive(void); 25 26/* pagevec tagged pointer */ 27typedef tagptr2_t erofs_vtptr_t; 28 29/* pagevec collector */ 30struct z_erofs_pagevec_ctor { 31 struct page *curr, *next; 32 erofs_vtptr_t *pages; 33 34 unsigned int nr, index; 35}; 36 37static inline void z_erofs_pagevec_ctor_exit(struct z_erofs_pagevec_ctor *ctor, 38 bool atomic) 39{ 40 if (!ctor->curr) 41 return; 42 43 if (atomic) 44 kunmap_atomic(ctor->pages); 45 else 46 kunmap(ctor->curr); 47} 48 49static inline struct page * 50z_erofs_pagevec_ctor_next_page(struct z_erofs_pagevec_ctor *ctor, 51 unsigned int nr) 52{ 53 unsigned int index; 54 55 /* keep away from occupied pages */ 56 if (ctor->next) 57 return ctor->next; 58 59 for (index = 0; index < nr; ++index) { 60 const erofs_vtptr_t t = ctor->pages[index]; 61 const unsigned int tags = tagptr_unfold_tags(t); 62 63 if (tags == Z_EROFS_PAGE_TYPE_EXCLUSIVE) 64 return tagptr_unfold_ptr(t); 65 } 66 DBG_BUGON(nr >= ctor->nr); 67 return NULL; 68} 69 70static inline void 71z_erofs_pagevec_ctor_pagedown(struct z_erofs_pagevec_ctor *ctor, 72 bool atomic) 73{ 74 struct page *next = z_erofs_pagevec_ctor_next_page(ctor, ctor->nr); 75 76 z_erofs_pagevec_ctor_exit(ctor, atomic); 77 78 ctor->curr = next; 79 ctor->next = NULL; 80 ctor->pages = atomic ? 81 kmap_atomic(ctor->curr) : kmap(ctor->curr); 82 83 ctor->nr = PAGE_SIZE / sizeof(struct page *); 84 ctor->index = 0; 85} 86 87static inline void z_erofs_pagevec_ctor_init(struct z_erofs_pagevec_ctor *ctor, 88 unsigned int nr, 89 erofs_vtptr_t *pages, 90 unsigned int i) 91{ 92 ctor->nr = nr; 93 ctor->curr = ctor->next = NULL; 94 ctor->pages = pages; 95 96 if (i >= nr) { 97 i -= nr; 98 z_erofs_pagevec_ctor_pagedown(ctor, false); 99 while (i > ctor->nr) { 100 i -= ctor->nr; 101 z_erofs_pagevec_ctor_pagedown(ctor, false); 102 } 103 } 104 ctor->next = z_erofs_pagevec_ctor_next_page(ctor, i); 105 ctor->index = i; 106} 107 108static inline bool z_erofs_pagevec_enqueue(struct z_erofs_pagevec_ctor *ctor, 109 struct page *page, 110 enum z_erofs_page_type type, 111 bool pvec_safereuse) 112{ 113 if (!ctor->next) { 114 /* some pages cannot be reused as pvec safely without I/O */ 115 if (type == Z_EROFS_PAGE_TYPE_EXCLUSIVE && !pvec_safereuse) 116 type = Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED; 117 118 if (type != Z_EROFS_PAGE_TYPE_EXCLUSIVE && 119 ctor->index + 1 == ctor->nr) 120 return false; 121 } 122 123 if (ctor->index >= ctor->nr) 124 z_erofs_pagevec_ctor_pagedown(ctor, false); 125 126 /* exclusive page type must be 0 */ 127 if (Z_EROFS_PAGE_TYPE_EXCLUSIVE != (uintptr_t)NULL) 128 __bad_page_type_exclusive(); 129 130 /* should remind that collector->next never equal to 1, 2 */ 131 if (type == (uintptr_t)ctor->next) { 132 ctor->next = page; 133 } 134 ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, page, type); 135 return true; 136} 137 138static inline struct page * 139z_erofs_pagevec_dequeue(struct z_erofs_pagevec_ctor *ctor, 140 enum z_erofs_page_type *type) 141{ 142 erofs_vtptr_t t; 143 144 if (ctor->index >= ctor->nr) { 145 DBG_BUGON(!ctor->next); 146 z_erofs_pagevec_ctor_pagedown(ctor, true); 147 } 148 149 t = ctor->pages[ctor->index]; 150 151 *type = tagptr_unfold_tags(t); 152 153 /* should remind that collector->next never equal to 1, 2 */ 154 if (*type == (uintptr_t)ctor->next) 155 ctor->next = tagptr_unfold_ptr(t); 156 157 ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, NULL, 0); 158 return tagptr_unfold_ptr(t); 159} 160#endif 161 162