include/linux/page-flags.h

   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 /*
  98  * Marks tail portion of a compound page. We currently do not reclaim
  99  * compound pages so we can reuse a flag only used for reclaim here.
 100  */
 101 #define PG_tail                 PG_reclaim
 102
 103 #if (BITS_PER_LONG > 32)
 104 /*
 105  * 64-bit-only flags build down from bit 31
 106  *
 107  * 32 bit  -------------------------------| FIELDS |       FLAGS         |
 108  * 64 bit  |           FIELDS             | ??????         FLAGS         |
 109  *         63                            32                              0
 110  */
 111 #define PG_uncached             31      /* Page has been mapped as uncached */
 112 #endif
 113
 114 /*
 115  * Manipulation of page state flags
 116  */
 117 #define PageLocked(page)                \
 118                 test_bit(PG_locked, &(page)->flags)
 119 #define SetPageLocked(page)             \
 120                 set_bit(PG_locked, &(page)->flags)
 121 #define TestSetPageLocked(page)         \
 122                 test_and_set_bit(PG_locked, &(page)->flags)
 123 #define ClearPageLocked(page)           \
 124                 clear_bit(PG_locked, &(page)->flags)
 125 #define TestClearPageLocked(page)       \
 126                 test_and_clear_bit(PG_locked, &(page)->flags)
 127
 128 #define PageError(page)         test_bit(PG_error, &(page)->flags)
 129 #define SetPageError(page)      set_bit(PG_error, &(page)->flags)
 130 #define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
 131
 132 #define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
 133 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
 134 #define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
 135 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
 136
 137 #define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
 138 #ifdef CONFIG_S390
 139 static inline void SetPageUptodate(struct page *page)
 140 {
 141         if (!test_and_set_bit(PG_uptodate, &page->flags))
 142                 page_clear_dirty(page);
 143 }
 144 #else
 145 #define SetPageUptodate(page)   set_bit(PG_uptodate, &(page)->flags)
 146 #endif
 147 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
 148
 149 #define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
 150 #define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
 151 #define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
 152 #define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
 153 #define __ClearPageDirty(page)  __clear_bit(PG_dirty, &(page)->flags)
 154 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 155
 156 #define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
 157 #define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
 158 #define ClearPageLRU(page)      clear_bit(PG_lru, &(page)->flags)
 159 #define __ClearPageLRU(page)    __clear_bit(PG_lru, &(page)->flags)
 160
 161 #define PageActive(page)        test_bit(PG_active, &(page)->flags)
 162 #define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
 163 #define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
 164 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
 165
 166 #define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
 167 #define __SetPageSlab(page)     __set_bit(PG_slab, &(page)->flags)
 168 #define __ClearPageSlab(page)   __clear_bit(PG_slab, &(page)->flags)
 169
 170 #ifdef CONFIG_HIGHMEM
 171 #define PageHighMem(page)       is_highmem(page_zone(page))
 172 #else
 173 #define PageHighMem(page)       0 /* needed to optimize away at compile time */
 174 #endif
 175
 176 #define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
 177 #define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
 178 #define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
 179
 180 #define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
 181 #define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
 182 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
 183 #define __ClearPageReserved(page)       __clear_bit(PG_reserved, &(page)->flags)
 184
 185 #define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
 186 #define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
 187 #define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
 188 #define __SetPagePrivate(page)  __set_bit(PG_private, &(page)->flags)
 189 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
 190
 191 #define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
 192 #define SetPageWriteback(page)                                          \
 193         do {                                                            \
 194                 if (!test_and_set_bit(PG_writeback,                     \
 195                                 &(page)->flags))                        \
 196                         inc_zone_page_state(page, NR_WRITEBACK);        \
 197         } while (0)
 198 #define TestSetPageWriteback(page)                                      \
 199         ({                                                              \
 200                 int ret;                                                \
 201                 ret = test_and_set_bit(PG_writeback,                    \
 202                                         &(page)->flags);                \
 203                 if (!ret)                                               \
 204                         inc_zone_page_state(page, NR_WRITEBACK);        \
 205                 ret;                                                    \
 206         })
 207 #define ClearPageWriteback(page)                                        \
 208         do {                                                            \
 209                 if (test_and_clear_bit(PG_writeback,                    \
 210                                 &(page)->flags))                        \
 211                         dec_zone_page_state(page, NR_WRITEBACK);        \
 212         } while (0)
 213 #define TestClearPageWriteback(page)                                    \
 214         ({                                                              \
 215                 int ret;                                                \
 216                 ret = test_and_clear_bit(PG_writeback,                  \
 217                                 &(page)->flags);                        \
 218                 if (ret)                                                \
 219                         dec_zone_page_state(page, NR_WRITEBACK);        \
 220                 ret;                                                    \
 221         })
 222
 223 #define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
 224 #define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
 225 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
 226 #define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
 227 #define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
 228
 229 #define PageNosaveFree(page)    test_bit(PG_nosave_free, &(page)->flags)
 230 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
 231 #define ClearPageNosaveFree(page)               clear_bit(PG_nosave_free, &(page)->flags)
 232
 233 #define PageBuddy(page)         test_bit(PG_buddy, &(page)->flags)
 234 #define __SetPageBuddy(page)    __set_bit(PG_buddy, &(page)->flags)
 235 #define __ClearPageBuddy(page)  __clear_bit(PG_buddy, &(page)->flags)
 236
 237 #define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
 238 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
 239 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
 240
 241 #define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
 242 #define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
 243 #define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
 244 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
 245
 246 #define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
 247 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
 248 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
 249
 250 /*
 251  * Note: PG_tail is an alias of another page flag. The result of PageTail()
 252  * is only valid if PageCompound(page) is true.
 253  */
 254 #define PageTail(page)  test_bit(PG_tail, &(page)->flags)
 255 #define __SetPageTail(page)     __set_bit(PG_tail, &(page)->flags)
 256 #define __ClearPageTail(page)   __clear_bit(PG_tail, &(page)->flags)
 257
 258 #ifdef CONFIG_SWAP
 259 #define PageSwapCache(page)     test_bit(PG_swapcache, &(page)->flags)
 260 #define SetPageSwapCache(page)  set_bit(PG_swapcache, &(page)->flags)
 261 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
 262 #else
 263 #define PageSwapCache(page)     0
 264 #endif
 265
 266 #define PageUncached(page)      test_bit(PG_uncached, &(page)->flags)
 267 #define SetPageUncached(page)   set_bit(PG_uncached, &(page)->flags)
 268 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
 269
 270 struct page;    /* forward declaration */
 271
 272 extern void cancel_dirty_page(struct page *page, unsigned int account_size);
 273
 274 int test_clear_page_writeback(struct page *page);
 275 int test_set_page_writeback(struct page *page);
 276
 277 static inline void set_page_writeback(struct page *page)
 278 {
 279         test_set_page_writeback(page);
 280 }
 281
 282 #endif  /* PAGE_FLAGS_H */