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/percpu.h>
   9 #include <linux/cache.h>
  10 #include <asm/pgtable.h>
  11
  12 /*
  13  * Various page->flags bits:
  14  *
  15  * PG_reserved is set for special pages, which can never be swapped out. Some
  16  * of them might not even exist (eg empty_bad_page)...
  17  *
  18  * The PG_private bitflag is set if page->private contains a valid value.
  19  *
  20  * During disk I/O, PG_locked is used. This bit is set before I/O and
  21  * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
  22  * waiting for the I/O on this page to complete.
  23  *
  24  * PG_uptodate tells whether the page's contents is valid.  When a read
  25  * completes, the page becomes uptodate, unless a disk I/O error happened.
  26  *
  27  * For choosing which pages to swap out, inode pages carry a PG_referenced bit,
  28  * which is set any time the system accesses that page through the (mapping,
  29  * index) hash table.  This referenced bit, together with the referenced bit
  30  * in the page tables, is used to manipulate page->age and move the page across
  31  * the active, inactive_dirty and inactive_clean lists.
  32  *
  33  * Note that the referenced bit, the page->lru list_head and the active,
  34  * inactive_dirty and inactive_clean lists are protected by the
  35  * zone->lru_lock, and *NOT* by the usual PG_locked bit!
  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
  49 /*
  50  * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
  51  * locked- and dirty-page accounting.  The top eight bits of page->flags are
  52  * used for page->zone, so putting flag bits there doesn't work.
  53  */
  54 #define PG_locked                0      /* Page is locked. Don't touch. */
  55 #define PG_error                 1
  56 #define PG_referenced            2
  57 #define PG_uptodate              3
  58
  59 #define PG_dirty                 4
  60 #define PG_lru                   5
  61 #define PG_active                6
  62 #define PG_slab                  7      /* slab debug (Suparna wants this) */
  63
  64 #define PG_highmem               8
  65 #define PG_checked               9      /* kill me in 2.5.<early>. */
  66 #define PG_arch_1               10
  67 #define PG_reserved             11
  68
  69 #define PG_private              12      /* Has something at ->private */
  70 #define PG_writeback            13      /* Page is under writeback */
  71 #define PG_nosave               14      /* Used for system suspend/resume */
  72 #define PG_chainlock            15      /* lock bit for ->pte_chain */
  73
  74 #define PG_direct               16      /* ->pte_chain points directly at pte */
  75 #define PG_mappedtodisk         17      /* Has blocks allocated on-disk */
  76 #define PG_reclaim              18      /* To be reclaimed asap */
  77 #define PG_compound             19      /* Part of a compound page */
  78
  79
  80 /*
  81  * Global page accounting.  One instance per CPU.  Only unsigned longs are
  82  * allowed.
  83  */
  84 struct page_state {
  85         unsigned long nr_dirty;         /* Dirty writeable pages */
  86         unsigned long nr_writeback;     /* Pages under writeback */
  87         unsigned long nr_unstable;      /* NFS unstable pages */
  88         unsigned long nr_page_table_pages;/* Pages used for pagetables */
  89         unsigned long nr_mapped;        /* mapped into pagetables */
  90         unsigned long nr_slab;          /* In slab */
  91 #define GET_PAGE_STATE_LAST nr_slab
  92
  93         /*
  94          * The below are zeroed by get_page_state().  Use get_full_page_state()
  95          * to add up all these.
  96          */
  97         unsigned long pgpgin;           /* Disk reads */
  98         unsigned long pgpgout;          /* Disk writes */
  99         unsigned long pswpin;           /* swap reads */
 100         unsigned long pswpout;          /* swap writes */
 101         unsigned long pgalloc;          /* page allocations */
 102
 103         unsigned long pgfree;           /* page freeings */
 104         unsigned long pgactivate;       /* pages moved inactive->active */
 105         unsigned long pgdeactivate;     /* pages moved active->inactive */
 106         unsigned long pgfault;          /* faults (major+minor) */
 107         unsigned long pgmajfault;       /* faults (major only) */
 108
 109         unsigned long pgscan;           /* pages scanned by page reclaim */
 110         unsigned long pgrefill;         /* inspected in refill_inactive_zone */
 111         unsigned long pgsteal;          /* total pages reclaimed */
 112         unsigned long pginodesteal;     /* pages reclaimed via inode freeing */
 113         unsigned long kswapd_steal;     /* pages reclaimed by kswapd */
 114
 115         unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
 116         unsigned long pageoutrun;       /* kswapd's calls to page reclaim */
 117         unsigned long allocstall;       /* direct reclaim calls */
 118         unsigned long pgrotated;        /* pages rotated to tail of the LRU */
 119 } ____cacheline_aligned;
 120
 121 DECLARE_PER_CPU(struct page_state, page_states);
 122
 123 extern void get_page_state(struct page_state *ret);
 124 extern void get_full_page_state(struct page_state *ret);
 125
 126 #define mod_page_state(member, delta)                                   \
 127         do {                                                            \
 128                 unsigned long flags;                                    \
 129                 local_irq_save(flags);                                  \
 130                 __get_cpu_var(page_states).member += (delta);           \
 131                 local_irq_restore(flags);                               \
 132         } while (0)
 133
 134 #define inc_page_state(member)  mod_page_state(member, 1UL)
 135 #define dec_page_state(member)  mod_page_state(member, 0UL - 1)
 136 #define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))
 137
 138
 139 /*
 140  * Manipulation of page state flags
 141  */
 142 #define PageLocked(page)                \
 143                 test_bit(PG_locked, &(page)->flags)
 144 #define SetPageLocked(page)             \
 145                 set_bit(PG_locked, &(page)->flags)
 146 #define TestSetPageLocked(page)         \
 147                 test_and_set_bit(PG_locked, &(page)->flags)
 148 #define ClearPageLocked(page)           \
 149                 clear_bit(PG_locked, &(page)->flags)
 150 #define TestClearPageLocked(page)       \
 151                 test_and_clear_bit(PG_locked, &(page)->flags)
 152
 153 #define PageError(page)         test_bit(PG_error, &(page)->flags)
 154 #define SetPageError(page)      set_bit(PG_error, &(page)->flags)
 155 #define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
 156
 157 #define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
 158 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
 159 #define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
 160 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
 161
 162 #ifndef arch_set_page_uptodate
 163 #define arch_set_page_uptodate(page) do { } while (0)
 164 #endif
 165
 166 #define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
 167 #define SetPageUptodate(page) \
 168         do {                                                            \
 169                 arch_set_page_uptodate(page);                           \
 170                 set_bit(PG_uptodate, &(page)->flags);                   \
 171         } while (0)
 172 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
 173
 174 #define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
 175 #define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
 176 #define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
 177 #define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
 178 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 179
 180 #define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
 181 #define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
 182 #define TestSetPageLRU(page)    test_and_set_bit(PG_lru, &(page)->flags)
 183 #define TestClearPageLRU(page)  test_and_clear_bit(PG_lru, &(page)->flags)
 184
 185 #define PageActive(page)        test_bit(PG_active, &(page)->flags)
 186 #define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
 187 #define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
 188 #define TestClearPageActive(page) test_and_clear_bit(PG_active, &(page)->flags)
 189 #define TestSetPageActive(page) test_and_set_bit(PG_active, &(page)->flags)
 190
 191 #define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
 192 #define SetPageSlab(page)       set_bit(PG_slab, &(page)->flags)
 193 #define ClearPageSlab(page)     clear_bit(PG_slab, &(page)->flags)
 194 #define TestClearPageSlab(page) test_and_clear_bit(PG_slab, &(page)->flags)
 195 #define TestSetPageSlab(page)   test_and_set_bit(PG_slab, &(page)->flags)
 196
 197 #ifdef CONFIG_HIGHMEM
 198 #define PageHighMem(page)       test_bit(PG_highmem, &(page)->flags)
 199 #else
 200 #define PageHighMem(page)       0 /* needed to optimize away at compile time */
 201 #endif
 202
 203 #define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
 204 #define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
 205 #define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
 206
 207 #define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
 208 #define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
 209 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
 210
 211 #define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
 212 #define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
 213 #define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
 214
 215 #define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
 216 #define SetPageWriteback(page)                                          \
 217         do {                                                            \
 218                 if (!test_and_set_bit(PG_writeback,                     \
 219                                 &(page)->flags))                        \
 220                         inc_page_state(nr_writeback);                   \
 221         } while (0)
 222 #define TestSetPageWriteback(page)                                      \
 223         ({                                                              \
 224                 int ret;                                                \
 225                 ret = test_and_set_bit(PG_writeback,                    \
 226                                         &(page)->flags);                \
 227                 if (!ret)                                               \
 228                         inc_page_state(nr_writeback);                   \
 229                 ret;                                                    \
 230         })
 231 #define ClearPageWriteback(page)                                        \
 232         do {                                                            \
 233                 if (test_and_clear_bit(PG_writeback,                    \
 234                                 &(page)->flags))                        \
 235                         dec_page_state(nr_writeback);                   \
 236         } while (0)
 237 #define TestClearPageWriteback(page)                                    \
 238         ({                                                              \
 239                 int ret;                                                \
 240                 ret = test_and_clear_bit(PG_writeback,                  \
 241                                 &(page)->flags);                        \
 242                 if (ret)                                                \
 243                         dec_page_state(nr_writeback);                   \
 244                 ret;                                                    \
 245         })
 246
 247 #define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
 248 #define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
 249 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
 250 #define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
 251 #define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
 252
 253 #define PageDirect(page)        test_bit(PG_direct, &(page)->flags)
 254 #define SetPageDirect(page)     set_bit(PG_direct, &(page)->flags)
 255 #define TestSetPageDirect(page) test_and_set_bit(PG_direct, &(page)->flags)
 256 #define ClearPageDirect(page)           clear_bit(PG_direct, &(page)->flags)
 257 #define TestClearPageDirect(page)       test_and_clear_bit(PG_direct, &(page)->flags)
 258
 259 #define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
 260 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
 261 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
 262
 263 #define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
 264 #define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
 265 #define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
 266 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
 267
 268 #define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
 269 #define SetPageCompound(page)   set_bit(PG_compound, &(page)->flags)
 270 #define ClearPageCompound(page) clear_bit(PG_compound, &(page)->flags)
 271
 272 /*
 273  * The PageSwapCache predicate doesn't use a PG_flag at this time,
 274  * but it may again do so one day.
 275  */
 276 #ifdef CONFIG_SWAP
 277 extern struct address_space swapper_space;
 278 #define PageSwapCache(page) ((page)->mapping == &swapper_space)
 279 #else
 280 #define PageSwapCache(page) 0
 281 #endif
 282
 283 struct page;    /* forward declaration */
 284
 285 int test_clear_page_dirty(struct page *page);
 286
 287 static inline void clear_page_dirty(struct page *page)
 288 {
 289         test_clear_page_dirty(page);
 290 }
 291
 292 #endif  /* PAGE_FLAGS_H */