page-flags.h 10 KB

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