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