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_compound             15      /* Part of a compound page */
  73
  74 #define PG_swapcache            16      /* Swap page: swp_entry_t in private */
  75 #define PG_mappedtodisk         17      /* Has blocks allocated on-disk */
  76 #define PG_reclaim              18      /* To be reclaimed asap */
  77 #define PG_nosave_free          19      /* Free, should not be written */
  78 #define PG_uncached             20      /* Page has been mapped as uncached */
  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_high;     /* page allocations */
 102
 103         unsigned long pgalloc_normal;
 104         unsigned long pgalloc_dma;
 105         unsigned long pgfree;           /* page freeings */
 106         unsigned long pgactivate;       /* pages moved inactive->active */
 107         unsigned long pgdeactivate;     /* pages moved active->inactive */
 108
 109         unsigned long pgfault;          /* faults (major+minor) */
 110         unsigned long pgmajfault;       /* faults (major only) */
 111         unsigned long pgrefill_high;    /* inspected in refill_inactive_zone */
 112         unsigned long pgrefill_normal;
 113         unsigned long pgrefill_dma;
 114
 115         unsigned long pgsteal_high;     /* total highmem pages reclaimed */
 116         unsigned long pgsteal_normal;
 117         unsigned long pgsteal_dma;
 118         unsigned long pgscan_kswapd_high;/* total highmem pages scanned */
 119         unsigned long pgscan_kswapd_normal;
 120
 121         unsigned long pgscan_kswapd_dma;
 122         unsigned long pgscan_direct_high;/* total highmem pages scanned */
 123         unsigned long pgscan_direct_normal;
 124         unsigned long pgscan_direct_dma;
 125         unsigned long pginodesteal;     /* pages reclaimed via inode freeing */
 126
 127         unsigned long slabs_scanned;    /* slab objects scanned */
 128         unsigned long kswapd_steal;     /* pages reclaimed by kswapd */
 129         unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
 130         unsigned long pageoutrun;       /* kswapd's calls to page reclaim */
 131         unsigned long allocstall;       /* direct reclaim calls */
 132
 133         unsigned long pgrotated;        /* pages rotated to tail of the LRU */
 134 };
 135
 136 extern void get_page_state(struct page_state *ret);
 137 extern void get_full_page_state(struct page_state *ret);
 138 extern unsigned long __read_page_state(unsigned offset);
 139 extern void __mod_page_state(unsigned offset, unsigned long delta);
 140
 141 #define read_page_state(member) \
 142         __read_page_state(offsetof(struct page_state, member))
 143
 144 #define mod_page_state(member, delta)   \
 145         __mod_page_state(offsetof(struct page_state, member), (delta))
 146
 147 #define inc_page_state(member)  mod_page_state(member, 1UL)
 148 #define dec_page_state(member)  mod_page_state(member, 0UL - 1)
 149 #define add_page_state(member,delta) mod_page_state(member, (delta))
 150 #define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))
 151
 152 #define mod_page_state_zone(zone, member, delta)                                \
 153         do {                                                                    \
 154                 unsigned offset;                                                \
 155                 if (is_highmem(zone))                                           \
 156                         offset = offsetof(struct page_state, member##_high);    \
 157                 else if (is_normal(zone))                                       \
 158                         offset = offsetof(struct page_state, member##_normal);  \
 159                 else                                                            \
 160                         offset = offsetof(struct page_state, member##_dma);     \
 161                 __mod_page_state(offset, (delta));                              \
 162         } while (0)
 163
 164 /*
 165  * Manipulation of page state flags
 166  */
 167 #define PageLocked(page)                \
 168                 test_bit(PG_locked, &(page)->flags)
 169 #define SetPageLocked(page)             \
 170                 set_bit(PG_locked, &(page)->flags)
 171 #define TestSetPageLocked(page)         \
 172                 test_and_set_bit(PG_locked, &(page)->flags)
 173 #define ClearPageLocked(page)           \
 174                 clear_bit(PG_locked, &(page)->flags)
 175 #define TestClearPageLocked(page)       \
 176                 test_and_clear_bit(PG_locked, &(page)->flags)
 177
 178 #define PageError(page)         test_bit(PG_error, &(page)->flags)
 179 #define SetPageError(page)      set_bit(PG_error, &(page)->flags)
 180 #define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
 181
 182 #define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
 183 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
 184 #define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
 185 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
 186
 187 #define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
 188 #ifndef SetPageUptodate
 189 #define SetPageUptodate(page)   set_bit(PG_uptodate, &(page)->flags)
 190 #endif
 191 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
 192
 193 #define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
 194 #define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
 195 #define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
 196 #define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
 197 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 198
 199 #define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
 200 #define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
 201 #define TestSetPageLRU(page)    test_and_set_bit(PG_lru, &(page)->flags)
 202 #define TestClearPageLRU(page)  test_and_clear_bit(PG_lru, &(page)->flags)
 203
 204 #define PageActive(page)        test_bit(PG_active, &(page)->flags)
 205 #define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
 206 #define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
 207 #define TestClearPageActive(page) test_and_clear_bit(PG_active, &(page)->flags)
 208 #define TestSetPageActive(page) test_and_set_bit(PG_active, &(page)->flags)
 209
 210 #define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
 211 #define SetPageSlab(page)       set_bit(PG_slab, &(page)->flags)
 212 #define ClearPageSlab(page)     clear_bit(PG_slab, &(page)->flags)
 213 #define TestClearPageSlab(page) test_and_clear_bit(PG_slab, &(page)->flags)
 214 #define TestSetPageSlab(page)   test_and_set_bit(PG_slab, &(page)->flags)
 215
 216 #ifdef CONFIG_HIGHMEM
 217 #define PageHighMem(page)       test_bit(PG_highmem, &(page)->flags)
 218 #else
 219 #define PageHighMem(page)       0 /* needed to optimize away at compile time */
 220 #endif
 221
 222 #define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
 223 #define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
 224 #define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
 225
 226 #define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
 227 #define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
 228 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
 229 #define __ClearPageReserved(page)       __clear_bit(PG_reserved, &(page)->flags)
 230
 231 #define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
 232 #define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
 233 #define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
 234 #define __SetPagePrivate(page)  __set_bit(PG_private, &(page)->flags)
 235 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
 236
 237 #define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
 238 #define SetPageWriteback(page)                                          \
 239         do {                                                            \
 240                 if (!test_and_set_bit(PG_writeback,                     \
 241                                 &(page)->flags))                        \
 242                         inc_page_state(nr_writeback);                   \
 243         } while (0)
 244 #define TestSetPageWriteback(page)                                      \
 245         ({                                                              \
 246                 int ret;                                                \
 247                 ret = test_and_set_bit(PG_writeback,                    \
 248                                         &(page)->flags);                \
 249                 if (!ret)                                               \
 250                         inc_page_state(nr_writeback);                   \
 251                 ret;                                                    \
 252         })
 253 #define ClearPageWriteback(page)                                        \
 254         do {                                                            \
 255                 if (test_and_clear_bit(PG_writeback,                    \
 256                                 &(page)->flags))                        \
 257                         dec_page_state(nr_writeback);                   \
 258         } while (0)
 259 #define TestClearPageWriteback(page)                                    \
 260         ({                                                              \
 261                 int ret;                                                \
 262                 ret = test_and_clear_bit(PG_writeback,                  \
 263                                 &(page)->flags);                        \
 264                 if (ret)                                                \
 265                         dec_page_state(nr_writeback);                   \
 266                 ret;                                                    \
 267         })
 268
 269 #define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
 270 #define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
 271 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
 272 #define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
 273 #define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
 274
 275 #define PageNosaveFree(page)    test_bit(PG_nosave_free, &(page)->flags)
 276 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
 277 #define ClearPageNosaveFree(page)               clear_bit(PG_nosave_free, &(page)->flags)
 278
 279 #define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
 280 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
 281 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
 282
 283 #define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
 284 #define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
 285 #define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
 286 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
 287
 288 #ifdef CONFIG_HUGETLB_PAGE
 289 #define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
 290 #else
 291 #define PageCompound(page)      0
 292 #endif
 293 #define SetPageCompound(page)   set_bit(PG_compound, &(page)->flags)
 294 #define ClearPageCompound(page) clear_bit(PG_compound, &(page)->flags)
 295
 296 #ifdef CONFIG_SWAP
 297 #define PageSwapCache(page)     test_bit(PG_swapcache, &(page)->flags)
 298 #define SetPageSwapCache(page)  set_bit(PG_swapcache, &(page)->flags)
 299 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
 300 #else
 301 #define PageSwapCache(page)     0
 302 #endif
 303
 304 #define PageUncached(page)      test_bit(PG_uncached, &(page)->flags)
 305 #define SetPageUncached(page)   set_bit(PG_uncached, &(page)->flags)
 306 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
 307
 308 struct page;    /* forward declaration */
 309
 310 int test_clear_page_dirty(struct page *page);
 311 int test_clear_page_writeback(struct page *page);
 312 int test_set_page_writeback(struct page *page);
 313
 314 static inline void clear_page_dirty(struct page *page)
 315 {
 316         test_clear_page_dirty(page);
 317 }
 318
 319 static inline void set_page_writeback(struct page *page)
 320 {
 321         test_set_page_writeback(page);
 322 }
 323
 324 #endif  /* PAGE_FLAGS_H */