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