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 #include <linux/mm_types.h> 10 11 /* 12 * Various page->flags bits: 13 * 14 * PG_reserved is set for special pages, which can never be swapped out. Some 15 * of them might not even exist (eg empty_bad_page)... 16 * 17 * The PG_private bitflag is set on pagecache pages if they contain filesystem 18 * specific data (which is normally at page->private). It can be used by 19 * private allocations for its own usage. 20 * 21 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O 22 * and cleared when writeback _starts_ or when read _completes_. PG_writeback 23 * is set before writeback starts and cleared when it finishes. 24 * 25 * PG_locked also pins a page in pagecache, and blocks truncation of the file 26 * while it is held. 27 * 28 * page_waitqueue(page) is a wait queue of all tasks waiting for the page 29 * to become unlocked. 30 * 31 * PG_uptodate tells whether the page's contents is valid. When a read 32 * completes, the page becomes uptodate, unless a disk I/O error happened. 33 * 34 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and 35 * file-backed pagecache (see mm/vmscan.c). 36 * 37 * PG_error is set to indicate that an I/O error occurred on this page. 38 * 39 * PG_arch_1 is an architecture specific page state bit. The generic code 40 * guarantees that this bit is cleared for a page when it first is entered into 41 * the page cache. 42 * 43 * PG_highmem pages are not permanently mapped into the kernel virtual address 44 * space, they need to be kmapped separately for doing IO on the pages. The 45 * struct page (these bits with information) are always mapped into kernel 46 * address space... 47 * 48 * PG_buddy is set to indicate that the page is free and in the buddy system 49 * (see mm/page_alloc.c). 50 * 51 */ 52 53 /* 54 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break 55 * locked- and dirty-page accounting. 56 * 57 * The page flags field is split into two parts, the main flags area 58 * which extends from the low bits upwards, and the fields area which 59 * extends from the high bits downwards. 60 * 61 * | FIELD | ... | FLAGS | 62 * N-1 ^ 0 63 * (N-FLAGS_RESERVED) 64 * 65 * The fields area is reserved for fields mapping zone, node and SPARSEMEM 66 * section. The boundry between these two areas is defined by 67 * FLAGS_RESERVED which defines the width of the fields section 68 * (see linux/mmzone.h). New flags must _not_ overlap with this area. 69 */ 70 #define PG_locked 0 /* Page is locked. Don't touch. */ 71 #define PG_error 1 72 #define PG_referenced 2 73 #define PG_uptodate 3 74 75 #define PG_dirty 4 76 #define PG_lru 5 77 #define PG_active 6 78 #define PG_slab 7 /* slab debug (Suparna wants this) */ 79 80 #define PG_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/ 81 #define PG_arch_1 9 82 #define PG_reserved 10 83 #define PG_private 11 /* If pagecache, has fs-private data */ 84 85 #define PG_writeback 12 /* Page is under writeback */ 86 #define PG_nosave 13 /* Used for system suspend/resume */ 87 #define PG_compound 14 /* Part of a compound page */ 88 #define PG_swapcache 15 /* Swap page: swp_entry_t in private */ 89 90 #define PG_mappedtodisk 16 /* Has blocks allocated on-disk */ 91 #define PG_reclaim 17 /* To be reclaimed asap */ 92 #define PG_nosave_free 18 /* Used for system suspend/resume */ 93 #define PG_buddy 19 /* Page is free, on buddy lists */ 94 95 /* PG_owner_priv_1 users should have descriptive aliases */ 96 #define PG_checked PG_owner_priv_1 /* Used by some filesystems */ 97 98 #if (BITS_PER_LONG > 32) 99 /* 100 * 64-bit-only flags build down from bit 31 101 * 102 * 32 bit -------------------------------| FIELDS | FLAGS | 103 * 64 bit | FIELDS | ?????? FLAGS | 104 * 63 32 0 105 */ 106 #define PG_uncached 31 /* Page has been mapped as uncached */ 107 #endif 108 109 /* 110 * Manipulation of page state flags 111 */ 112 #define PageLocked(page) \ 113 test_bit(PG_locked, &(page)->flags) 114 #define SetPageLocked(page) \ 115 set_bit(PG_locked, &(page)->flags) 116 #define TestSetPageLocked(page) \ 117 test_and_set_bit(PG_locked, &(page)->flags) 118 #define ClearPageLocked(page) \ 119 clear_bit(PG_locked, &(page)->flags) 120 #define TestClearPageLocked(page) \ 121 test_and_clear_bit(PG_locked, &(page)->flags) 122 123 #define PageError(page) test_bit(PG_error, &(page)->flags) 124 #define SetPageError(page) set_bit(PG_error, &(page)->flags) 125 #define ClearPageError(page) clear_bit(PG_error, &(page)->flags) 126 127 #define PageReferenced(page) test_bit(PG_referenced, &(page)->flags) 128 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags) 129 #define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags) 130 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags) 131 132 #define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags) 133 #ifdef CONFIG_S390 134 static inline void SetPageUptodate(struct page *page) 135 { 136 if (!test_and_set_bit(PG_uptodate, &page->flags)) 137 page_clear_dirty(page); 138 } 139 #else 140 #define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags) 141 #endif 142 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags) 143 144 #define PageDirty(page) test_bit(PG_dirty, &(page)->flags) 145 #define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags) 146 #define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags) 147 #define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags) 148 #define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags) 149 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags) 150 151 #define PageLRU(page) test_bit(PG_lru, &(page)->flags) 152 #define SetPageLRU(page) set_bit(PG_lru, &(page)->flags) 153 #define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags) 154 #define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags) 155 156 #define PageActive(page) test_bit(PG_active, &(page)->flags) 157 #define SetPageActive(page) set_bit(PG_active, &(page)->flags) 158 #define ClearPageActive(page) clear_bit(PG_active, &(page)->flags) 159 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags) 160 161 #define PageSlab(page) test_bit(PG_slab, &(page)->flags) 162 #define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags) 163 #define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags) 164 165 #ifdef CONFIG_HIGHMEM 166 #define PageHighMem(page) is_highmem(page_zone(page)) 167 #else 168 #define PageHighMem(page) 0 /* needed to optimize away at compile time */ 169 #endif 170 171 #define PageChecked(page) test_bit(PG_checked, &(page)->flags) 172 #define SetPageChecked(page) set_bit(PG_checked, &(page)->flags) 173 #define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags) 174 175 #define PageReserved(page) test_bit(PG_reserved, &(page)->flags) 176 #define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags) 177 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags) 178 #define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags) 179 180 #define SetPagePrivate(page) set_bit(PG_private, &(page)->flags) 181 #define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags) 182 #define PagePrivate(page) test_bit(PG_private, &(page)->flags) 183 #define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags) 184 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags) 185 186 #define PageWriteback(page) test_bit(PG_writeback, &(page)->flags) 187 #define SetPageWriteback(page) \ 188 do { \ 189 if (!test_and_set_bit(PG_writeback, \ 190 &(page)->flags)) \ 191 inc_zone_page_state(page, NR_WRITEBACK); \ 192 } while (0) 193 #define TestSetPageWriteback(page) \ 194 ({ \ 195 int ret; \ 196 ret = test_and_set_bit(PG_writeback, \ 197 &(page)->flags); \ 198 if (!ret) \ 199 inc_zone_page_state(page, NR_WRITEBACK); \ 200 ret; \ 201 }) 202 #define ClearPageWriteback(page) \ 203 do { \ 204 if (test_and_clear_bit(PG_writeback, \ 205 &(page)->flags)) \ 206 dec_zone_page_state(page, NR_WRITEBACK); \ 207 } while (0) 208 #define TestClearPageWriteback(page) \ 209 ({ \ 210 int ret; \ 211 ret = test_and_clear_bit(PG_writeback, \ 212 &(page)->flags); \ 213 if (ret) \ 214 dec_zone_page_state(page, NR_WRITEBACK); \ 215 ret; \ 216 }) 217 218 #define PageNosave(page) test_bit(PG_nosave, &(page)->flags) 219 #define SetPageNosave(page) set_bit(PG_nosave, &(page)->flags) 220 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags) 221 #define ClearPageNosave(page) clear_bit(PG_nosave, &(page)->flags) 222 #define TestClearPageNosave(page) test_and_clear_bit(PG_nosave, &(page)->flags) 223 224 #define PageNosaveFree(page) test_bit(PG_nosave_free, &(page)->flags) 225 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags) 226 #define ClearPageNosaveFree(page) clear_bit(PG_nosave_free, &(page)->flags) 227 228 #define PageBuddy(page) test_bit(PG_buddy, &(page)->flags) 229 #define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags) 230 #define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags) 231 232 #define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags) 233 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags) 234 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags) 235 236 #define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags) 237 #define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags) 238 #define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags) 239 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags) 240 241 #define PageCompound(page) test_bit(PG_compound, &(page)->flags) 242 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags) 243 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags) 244 245 /* 246 * PG_reclaim is used in combination with PG_compound to mark the 247 * head and tail of a compound page 248 * 249 * PG_compound & PG_reclaim => Tail page 250 * PG_compound & ~PG_reclaim => Head page 251 */ 252 253 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) 254 255 #define PageTail(page) ((page->flags & PG_head_tail_mask) \ 256 == PG_head_tail_mask) 257 258 static inline void __SetPageTail(struct page *page) 259 { 260 page->flags |= PG_head_tail_mask; 261 } 262 263 static inline void __ClearPageTail(struct page *page) 264 { 265 page->flags &= ~PG_head_tail_mask; 266 } 267 268 #define PageHead(page) ((page->flags & PG_head_tail_mask) \ 269 == (1L << PG_compound)) 270 #define __SetPageHead(page) __SetPageCompound(page) 271 #define __ClearPageHead(page) __ClearPageCompound(page) 272 273 #ifdef CONFIG_SWAP 274 #define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags) 275 #define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags) 276 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags) 277 #else 278 #define PageSwapCache(page) 0 279 #endif 280 281 #define PageUncached(page) test_bit(PG_uncached, &(page)->flags) 282 #define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags) 283 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags) 284 285 struct page; /* forward declaration */ 286 287 extern void cancel_dirty_page(struct page *page, unsigned int account_size); 288 289 int test_clear_page_writeback(struct page *page); 290 int test_set_page_writeback(struct page *page); 291 292 static inline void set_page_writeback(struct page *page) 293 { 294 test_set_page_writeback(page); 295 } 296 297 #endif /* PAGE_FLAGS_H */ 298