1 /* 2 * Macros for manipulating and testing page->flags 3 */ 4 5 #ifndef PAGE_FLAGS_H 6 #define PAGE_FLAGS_H 7 8 #include <linux/types.h> 9 10 /* 11 * Various page->flags bits: 12 * 13 * PG_reserved is set for special pages, which can never be swapped out. Some 14 * of them might not even exist (eg empty_bad_page)... 15 * 16 * The PG_private bitflag is set if page->private contains a valid value. 17 * 18 * During disk I/O, PG_locked is used. This bit is set before I/O and 19 * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks 20 * waiting for the I/O on this page to complete. 21 * 22 * PG_uptodate tells whether the page's contents is valid. When a read 23 * completes, the page becomes uptodate, unless a disk I/O error happened. 24 * 25 * For choosing which pages to swap out, inode pages carry a PG_referenced bit, 26 * which is set any time the system accesses that page through the (mapping, 27 * index) hash table. This referenced bit, together with the referenced bit 28 * in the page tables, is used to manipulate page->age and move the page across 29 * the active, inactive_dirty and inactive_clean lists. 30 * 31 * Note that the referenced bit, the page->lru list_head and the active, 32 * inactive_dirty and inactive_clean lists are protected by the 33 * zone->lru_lock, and *NOT* by the usual PG_locked bit! 34 * 35 * PG_error is set to indicate that an I/O error occurred on this page. 36 * 37 * PG_arch_1 is an architecture specific page state bit. The generic code 38 * guarantees that this bit is cleared for a page when it first is entered into 39 * the page cache. 40 * 41 * PG_highmem pages are not permanently mapped into the kernel virtual address 42 * space, they need to be kmapped separately for doing IO on the pages. The 43 * struct page (these bits with information) are always mapped into kernel 44 * address space... 45 */ 46 47 /* 48 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break 49 * locked- and dirty-page accounting. 50 * 51 * The page flags field is split into two parts, the main flags area 52 * which extends from the low bits upwards, and the fields area which 53 * extends from the high bits downwards. 54 * 55 * | FIELD | ... | FLAGS | 56 * N-1 ^ 0 57 * (N-FLAGS_RESERVED) 58 * 59 * The fields area is reserved for fields mapping zone, node and SPARSEMEM 60 * section. The boundry between these two areas is defined by 61 * FLAGS_RESERVED which defines the width of the fields section 62 * (see linux/mmzone.h). New flags must _not_ overlap with this area. 63 */ 64 #define PG_locked 0 /* Page is locked. Don't touch. */ 65 #define PG_error 1 66 #define PG_referenced 2 67 #define PG_uptodate 3 68 69 #define PG_dirty 4 70 #define PG_lru 5 71 #define PG_active 6 72 #define PG_slab 7 /* slab debug (Suparna wants this) */ 73 74 #define PG_checked 8 /* kill me in 2.5.<early>. */ 75 #define PG_arch_1 9 76 #define PG_reserved 10 77 #define PG_private 11 /* Has something at ->private */ 78 79 #define PG_writeback 12 /* Page is under writeback */ 80 #define PG_nosave 13 /* Used for system suspend/resume */ 81 #define PG_compound 14 /* Part of a compound page */ 82 #define PG_swapcache 15 /* Swap page: swp_entry_t in private */ 83 84 #define PG_mappedtodisk 16 /* Has blocks allocated on-disk */ 85 #define PG_reclaim 17 /* To be reclaimed asap */ 86 #define PG_nosave_free 18 /* Free, should not be written */ 87 #define PG_buddy 19 /* Page is free, on buddy lists */ 88 89 90 #if (BITS_PER_LONG > 32) 91 /* 92 * 64-bit-only flags build down from bit 31 93 * 94 * 32 bit -------------------------------| FIELDS | FLAGS | 95 * 64 bit | FIELDS | ?????? FLAGS | 96 * 63 32 0 97 */ 98 #define PG_uncached 31 /* Page has been mapped as uncached */ 99 #endif 100 101 /* 102 * Manipulation of page state flags 103 */ 104 #define PageLocked(page) \ 105 test_bit(PG_locked, &(page)->flags) 106 #define SetPageLocked(page) \ 107 set_bit(PG_locked, &(page)->flags) 108 #define TestSetPageLocked(page) \ 109 test_and_set_bit(PG_locked, &(page)->flags) 110 #define ClearPageLocked(page) \ 111 clear_bit(PG_locked, &(page)->flags) 112 #define TestClearPageLocked(page) \ 113 test_and_clear_bit(PG_locked, &(page)->flags) 114 115 #define PageError(page) test_bit(PG_error, &(page)->flags) 116 #define SetPageError(page) set_bit(PG_error, &(page)->flags) 117 #define ClearPageError(page) clear_bit(PG_error, &(page)->flags) 118 119 #define PageReferenced(page) test_bit(PG_referenced, &(page)->flags) 120 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags) 121 #define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags) 122 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags) 123 124 #define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags) 125 #ifdef CONFIG_S390 126 #define SetPageUptodate(_page) \ 127 do { \ 128 struct page *__page = (_page); \ 129 if (!test_and_set_bit(PG_uptodate, &__page->flags)) \ 130 page_test_and_clear_dirty(_page); \ 131 } while (0) 132 #else 133 #define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags) 134 #endif 135 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags) 136 137 #define PageDirty(page) test_bit(PG_dirty, &(page)->flags) 138 #define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags) 139 #define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags) 140 #define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags) 141 #define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags) 142 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags) 143 144 #define PageLRU(page) test_bit(PG_lru, &(page)->flags) 145 #define SetPageLRU(page) set_bit(PG_lru, &(page)->flags) 146 #define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags) 147 #define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags) 148 149 #define PageActive(page) test_bit(PG_active, &(page)->flags) 150 #define SetPageActive(page) set_bit(PG_active, &(page)->flags) 151 #define ClearPageActive(page) clear_bit(PG_active, &(page)->flags) 152 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags) 153 154 #define PageSlab(page) test_bit(PG_slab, &(page)->flags) 155 #define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags) 156 #define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags) 157 158 #ifdef CONFIG_HIGHMEM 159 #define PageHighMem(page) is_highmem(page_zone(page)) 160 #else 161 #define PageHighMem(page) 0 /* needed to optimize away at compile time */ 162 #endif 163 164 #define PageChecked(page) test_bit(PG_checked, &(page)->flags) 165 #define SetPageChecked(page) set_bit(PG_checked, &(page)->flags) 166 #define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags) 167 168 #define PageReserved(page) test_bit(PG_reserved, &(page)->flags) 169 #define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags) 170 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags) 171 #define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags) 172 173 #define SetPagePrivate(page) set_bit(PG_private, &(page)->flags) 174 #define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags) 175 #define PagePrivate(page) test_bit(PG_private, &(page)->flags) 176 #define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags) 177 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags) 178 179 #define PageWriteback(page) test_bit(PG_writeback, &(page)->flags) 180 #define SetPageWriteback(page) \ 181 do { \ 182 if (!test_and_set_bit(PG_writeback, \ 183 &(page)->flags)) \ 184 inc_zone_page_state(page, NR_WRITEBACK); \ 185 } while (0) 186 #define TestSetPageWriteback(page) \ 187 ({ \ 188 int ret; \ 189 ret = test_and_set_bit(PG_writeback, \ 190 &(page)->flags); \ 191 if (!ret) \ 192 inc_zone_page_state(page, NR_WRITEBACK); \ 193 ret; \ 194 }) 195 #define ClearPageWriteback(page) \ 196 do { \ 197 if (test_and_clear_bit(PG_writeback, \ 198 &(page)->flags)) \ 199 dec_zone_page_state(page, NR_WRITEBACK); \ 200 } while (0) 201 #define TestClearPageWriteback(page) \ 202 ({ \ 203 int ret; \ 204 ret = test_and_clear_bit(PG_writeback, \ 205 &(page)->flags); \ 206 if (ret) \ 207 dec_zone_page_state(page, NR_WRITEBACK); \ 208 ret; \ 209 }) 210 211 #define PageNosave(page) test_bit(PG_nosave, &(page)->flags) 212 #define SetPageNosave(page) set_bit(PG_nosave, &(page)->flags) 213 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags) 214 #define ClearPageNosave(page) clear_bit(PG_nosave, &(page)->flags) 215 #define TestClearPageNosave(page) test_and_clear_bit(PG_nosave, &(page)->flags) 216 217 #define PageNosaveFree(page) test_bit(PG_nosave_free, &(page)->flags) 218 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags) 219 #define ClearPageNosaveFree(page) clear_bit(PG_nosave_free, &(page)->flags) 220 221 #define PageBuddy(page) test_bit(PG_buddy, &(page)->flags) 222 #define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags) 223 #define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags) 224 225 #define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags) 226 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags) 227 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags) 228 229 #define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags) 230 #define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags) 231 #define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags) 232 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags) 233 234 #define PageCompound(page) test_bit(PG_compound, &(page)->flags) 235 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags) 236 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags) 237 238 #ifdef CONFIG_SWAP 239 #define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags) 240 #define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags) 241 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags) 242 #else 243 #define PageSwapCache(page) 0 244 #endif 245 246 #define PageUncached(page) test_bit(PG_uncached, &(page)->flags) 247 #define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags) 248 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags) 249 250 struct page; /* forward declaration */ 251 252 int test_clear_page_dirty(struct page *page); 253 int test_clear_page_writeback(struct page *page); 254 int test_set_page_writeback(struct page *page); 255 256 static inline void clear_page_dirty(struct page *page) 257 { 258 test_clear_page_dirty(page); 259 } 260 261 static inline void set_page_writeback(struct page *page) 262 { 263 test_set_page_writeback(page); 264 } 265 266 #endif /* PAGE_FLAGS_H */ 267