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_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/ 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 /* PG_owner_priv_1 users should have descriptive aliases */ 95 #define PG_checked PG_owner_priv_1 /* Used by some filesystems */ 96 97 #if (BITS_PER_LONG > 32) 98 /* 99 * 64-bit-only flags build down from bit 31 100 * 101 * 32 bit -------------------------------| FIELDS | FLAGS | 102 * 64 bit | FIELDS | ?????? FLAGS | 103 * 63 32 0 104 */ 105 #define PG_uncached 31 /* Page has been mapped as uncached */ 106 #endif 107 108 /* 109 * Manipulation of page state flags 110 */ 111 #define PageLocked(page) \ 112 test_bit(PG_locked, &(page)->flags) 113 #define SetPageLocked(page) \ 114 set_bit(PG_locked, &(page)->flags) 115 #define TestSetPageLocked(page) \ 116 test_and_set_bit(PG_locked, &(page)->flags) 117 #define ClearPageLocked(page) \ 118 clear_bit(PG_locked, &(page)->flags) 119 #define TestClearPageLocked(page) \ 120 test_and_clear_bit(PG_locked, &(page)->flags) 121 122 #define PageError(page) test_bit(PG_error, &(page)->flags) 123 #define SetPageError(page) set_bit(PG_error, &(page)->flags) 124 #define ClearPageError(page) clear_bit(PG_error, &(page)->flags) 125 126 #define PageReferenced(page) test_bit(PG_referenced, &(page)->flags) 127 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags) 128 #define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags) 129 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags) 130 131 #define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags) 132 #ifdef CONFIG_S390 133 static inline void SetPageUptodate(struct page *page) 134 { 135 if (!test_and_set_bit(PG_uptodate, &page->flags)) 136 page_test_and_clear_dirty(page); 137 } 138 #else 139 #define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags) 140 #endif 141 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags) 142 143 #define PageDirty(page) test_bit(PG_dirty, &(page)->flags) 144 #define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags) 145 #define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags) 146 #define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags) 147 #define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags) 148 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags) 149 150 #define PageLRU(page) test_bit(PG_lru, &(page)->flags) 151 #define SetPageLRU(page) set_bit(PG_lru, &(page)->flags) 152 #define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags) 153 #define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags) 154 155 #define PageActive(page) test_bit(PG_active, &(page)->flags) 156 #define SetPageActive(page) set_bit(PG_active, &(page)->flags) 157 #define ClearPageActive(page) clear_bit(PG_active, &(page)->flags) 158 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags) 159 160 #define PageSlab(page) test_bit(PG_slab, &(page)->flags) 161 #define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags) 162 #define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags) 163 164 #ifdef CONFIG_HIGHMEM 165 #define PageHighMem(page) is_highmem(page_zone(page)) 166 #else 167 #define PageHighMem(page) 0 /* needed to optimize away at compile time */ 168 #endif 169 170 #define PageChecked(page) test_bit(PG_checked, &(page)->flags) 171 #define SetPageChecked(page) set_bit(PG_checked, &(page)->flags) 172 #define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags) 173 174 #define PageReserved(page) test_bit(PG_reserved, &(page)->flags) 175 #define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags) 176 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags) 177 #define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags) 178 179 #define SetPagePrivate(page) set_bit(PG_private, &(page)->flags) 180 #define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags) 181 #define PagePrivate(page) test_bit(PG_private, &(page)->flags) 182 #define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags) 183 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags) 184 185 #define PageWriteback(page) test_bit(PG_writeback, &(page)->flags) 186 #define SetPageWriteback(page) \ 187 do { \ 188 if (!test_and_set_bit(PG_writeback, \ 189 &(page)->flags)) \ 190 inc_zone_page_state(page, NR_WRITEBACK); \ 191 } while (0) 192 #define TestSetPageWriteback(page) \ 193 ({ \ 194 int ret; \ 195 ret = test_and_set_bit(PG_writeback, \ 196 &(page)->flags); \ 197 if (!ret) \ 198 inc_zone_page_state(page, NR_WRITEBACK); \ 199 ret; \ 200 }) 201 #define ClearPageWriteback(page) \ 202 do { \ 203 if (test_and_clear_bit(PG_writeback, \ 204 &(page)->flags)) \ 205 dec_zone_page_state(page, NR_WRITEBACK); \ 206 } while (0) 207 #define TestClearPageWriteback(page) \ 208 ({ \ 209 int ret; \ 210 ret = test_and_clear_bit(PG_writeback, \ 211 &(page)->flags); \ 212 if (ret) \ 213 dec_zone_page_state(page, NR_WRITEBACK); \ 214 ret; \ 215 }) 216 217 #define PageNosave(page) test_bit(PG_nosave, &(page)->flags) 218 #define SetPageNosave(page) set_bit(PG_nosave, &(page)->flags) 219 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags) 220 #define ClearPageNosave(page) clear_bit(PG_nosave, &(page)->flags) 221 #define TestClearPageNosave(page) test_and_clear_bit(PG_nosave, &(page)->flags) 222 223 #define PageNosaveFree(page) test_bit(PG_nosave_free, &(page)->flags) 224 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags) 225 #define ClearPageNosaveFree(page) clear_bit(PG_nosave_free, &(page)->flags) 226 227 #define PageBuddy(page) test_bit(PG_buddy, &(page)->flags) 228 #define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags) 229 #define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags) 230 231 #define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags) 232 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags) 233 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags) 234 235 #define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags) 236 #define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags) 237 #define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags) 238 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags) 239 240 #define PageCompound(page) test_bit(PG_compound, &(page)->flags) 241 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags) 242 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags) 243 244 #ifdef CONFIG_SWAP 245 #define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags) 246 #define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags) 247 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags) 248 #else 249 #define PageSwapCache(page) 0 250 #endif 251 252 #define PageUncached(page) test_bit(PG_uncached, &(page)->flags) 253 #define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags) 254 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags) 255 256 struct page; /* forward declaration */ 257 258 extern void cancel_dirty_page(struct page *page, unsigned int account_size); 259 260 int test_clear_page_writeback(struct page *page); 261 int test_set_page_writeback(struct page *page); 262 263 static inline void set_page_writeback(struct page *page) 264 { 265 test_set_page_writeback(page); 266 } 267 268 #endif /* PAGE_FLAGS_H */ 269