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.
  52  *
  53  * The page flags field is split into two parts, the main flags area
  54  * which extends from the low bits upwards, and the fields area which
  55  * extends from the high bits downwards.
  56  *
  57  *  | FIELD | ... | FLAGS |
  58  *  N-1     ^             0
  59  *          (N-FLAGS_RESERVED)
  60  *
  61  * The fields area is reserved for fields mapping zone, node and SPARSEMEM
  62  * section.  The boundry between these two areas is defined by
  63  * FLAGS_RESERVED which defines the width of the fields section
  64  * (see linux/mmzone.h).  New flags must _not_ overlap with this area.
  65  */
  66 #define PG_locked                0      /* Page is locked. Don't touch. */
  67 #define PG_error                 1
  68 #define PG_referenced            2
  69 #define PG_uptodate              3
  70
  71 #define PG_dirty                 4
  72 #define PG_lru                   5
  73 #define PG_active                6
  74 #define PG_slab                  7      /* slab debug (Suparna wants this) */
  75
  76 #define PG_checked               8      /* kill me in 2.5.<early>. */
  77 #define PG_arch_1                9
  78 #define PG_reserved             10
  79 #define PG_private              11      /* Has something at ->private */
  80
  81 #define PG_writeback            12      /* Page is under writeback */
  82 #define PG_nosave               13      /* Used for system suspend/resume */
  83 #define PG_compound             14      /* Part of a compound page */
  84 #define PG_swapcache            15      /* Swap page: swp_entry_t in private */
  85
  86 #define PG_mappedtodisk         16      /* Has blocks allocated on-disk */
  87 #define PG_reclaim              17      /* To be reclaimed asap */
  88 #define PG_nosave_free          18      /* Free, should not be written */
  89 #define PG_buddy                19      /* Page is free, on buddy lists */
  90
  91 #define PG_uncached             20      /* Page has been mapped as uncached */
  92
  93 /*
  94  * Global page accounting.  One instance per CPU.  Only unsigned longs are
  95  * allowed.
  96  *
  97  * - Fields can be modified with xxx_page_state and xxx_page_state_zone at
  98  * any time safely (which protects the instance from modification by
  99  * interrupt.
 100  * - The __xxx_page_state variants can be used safely when interrupts are
 101  * disabled.
 102  * - The __xxx_page_state variants can be used if the field is only
 103  * modified from process context and protected from preemption, or only
 104  * modified from interrupt context.  In this case, the field should be
 105  * commented here.
 106  */
 107 struct page_state {
 108         unsigned long nr_dirty;         /* Dirty writeable pages */
 109         unsigned long nr_writeback;     /* Pages under writeback */
 110         unsigned long nr_unstable;      /* NFS unstable pages */
 111         unsigned long nr_page_table_pages;/* Pages used for pagetables */
 112         unsigned long nr_mapped;        /* mapped into pagetables.
 113                                          * only modified from process context */
 114         unsigned long nr_slab;          /* In slab */
 115 #define GET_PAGE_STATE_LAST nr_slab
 116
 117         /*
 118          * The below are zeroed by get_page_state().  Use get_full_page_state()
 119          * to add up all these.
 120          */
 121         unsigned long pgpgin;           /* Disk reads */
 122         unsigned long pgpgout;          /* Disk writes */
 123         unsigned long pswpin;           /* swap reads */
 124         unsigned long pswpout;          /* swap writes */
 125
 126         unsigned long pgalloc_high;     /* page allocations */
 127         unsigned long pgalloc_normal;
 128         unsigned long pgalloc_dma32;
 129         unsigned long pgalloc_dma;
 130
 131         unsigned long pgfree;           /* page freeings */
 132         unsigned long pgactivate;       /* pages moved inactive->active */
 133         unsigned long pgdeactivate;     /* pages moved active->inactive */
 134
 135         unsigned long pgfault;          /* faults (major+minor) */
 136         unsigned long pgmajfault;       /* faults (major only) */
 137
 138         unsigned long pgrefill_high;    /* inspected in refill_inactive_zone */
 139         unsigned long pgrefill_normal;
 140         unsigned long pgrefill_dma32;
 141         unsigned long pgrefill_dma;
 142
 143         unsigned long pgsteal_high;     /* total highmem pages reclaimed */
 144         unsigned long pgsteal_normal;
 145         unsigned long pgsteal_dma32;
 146         unsigned long pgsteal_dma;
 147
 148         unsigned long pgscan_kswapd_high;/* total highmem pages scanned */
 149         unsigned long pgscan_kswapd_normal;
 150         unsigned long pgscan_kswapd_dma32;
 151         unsigned long pgscan_kswapd_dma;
 152
 153         unsigned long pgscan_direct_high;/* total highmem pages scanned */
 154         unsigned long pgscan_direct_normal;
 155         unsigned long pgscan_direct_dma32;
 156         unsigned long pgscan_direct_dma;
 157
 158         unsigned long pginodesteal;     /* pages reclaimed via inode freeing */
 159         unsigned long slabs_scanned;    /* slab objects scanned */
 160         unsigned long kswapd_steal;     /* pages reclaimed by kswapd */
 161         unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
 162         unsigned long pageoutrun;       /* kswapd's calls to page reclaim */
 163         unsigned long allocstall;       /* direct reclaim calls */
 164
 165         unsigned long pgrotated;        /* pages rotated to tail of the LRU */
 166         unsigned long nr_bounce;        /* pages for bounce buffers */
 167 };
 168
 169 extern void get_page_state(struct page_state *ret);
 170 extern void get_page_state_node(struct page_state *ret, int node);
 171 extern void get_full_page_state(struct page_state *ret);
 172 extern unsigned long read_page_state_offset(unsigned long offset);
 173 extern void mod_page_state_offset(unsigned long offset, unsigned long delta);
 174 extern void __mod_page_state_offset(unsigned long offset, unsigned long delta);
 175
 176 #define read_page_state(member) \
 177         read_page_state_offset(offsetof(struct page_state, member))
 178
 179 #define mod_page_state(member, delta)   \
 180         mod_page_state_offset(offsetof(struct page_state, member), (delta))
 181
 182 #define __mod_page_state(member, delta) \
 183         __mod_page_state_offset(offsetof(struct page_state, member), (delta))
 184
 185 #define inc_page_state(member)          mod_page_state(member, 1UL)
 186 #define dec_page_state(member)          mod_page_state(member, 0UL - 1)
 187 #define add_page_state(member,delta)    mod_page_state(member, (delta))
 188 #define sub_page_state(member,delta)    mod_page_state(member, 0UL - (delta))
 189
 190 #define __inc_page_state(member)        __mod_page_state(member, 1UL)
 191 #define __dec_page_state(member)        __mod_page_state(member, 0UL - 1)
 192 #define __add_page_state(member,delta)  __mod_page_state(member, (delta))
 193 #define __sub_page_state(member,delta)  __mod_page_state(member, 0UL - (delta))
 194
 195 #define page_state(member) (*__page_state(offsetof(struct page_state, member)))
 196
 197 #define state_zone_offset(zone, member)                                 \
 198 ({                                                                      \
 199         unsigned offset;                                                \
 200         if (is_highmem(zone))                                           \
 201                 offset = offsetof(struct page_state, member##_high);    \
 202         else if (is_normal(zone))                                       \
 203                 offset = offsetof(struct page_state, member##_normal);  \
 204         else if (is_dma32(zone))                                        \
 205                 offset = offsetof(struct page_state, member##_dma32);   \
 206         else                                                            \
 207                 offset = offsetof(struct page_state, member##_dma);     \
 208         offset;                                                         \
 209 })
 210
 211 #define __mod_page_state_zone(zone, member, delta)                      \
 212  do {                                                                   \
 213         __mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
 214  } while (0)
 215
 216 #define mod_page_state_zone(zone, member, delta)                        \
 217  do {                                                                   \
 218         mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
 219  } while (0)
 220
 221 /*
 222  * Manipulation of page state flags
 223  */
 224 #define PageLocked(page)                \
 225                 test_bit(PG_locked, &(page)->flags)
 226 #define SetPageLocked(page)             \
 227                 set_bit(PG_locked, &(page)->flags)
 228 #define TestSetPageLocked(page)         \
 229                 test_and_set_bit(PG_locked, &(page)->flags)
 230 #define ClearPageLocked(page)           \
 231                 clear_bit(PG_locked, &(page)->flags)
 232 #define TestClearPageLocked(page)       \
 233                 test_and_clear_bit(PG_locked, &(page)->flags)
 234
 235 #define PageError(page)         test_bit(PG_error, &(page)->flags)
 236 #define SetPageError(page)      set_bit(PG_error, &(page)->flags)
 237 #define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
 238
 239 #define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
 240 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
 241 #define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
 242 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
 243
 244 #define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
 245 #ifndef SetPageUptodate
 246 #define SetPageUptodate(page)   set_bit(PG_uptodate, &(page)->flags)
 247 #endif
 248 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
 249
 250 #define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
 251 #define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
 252 #define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
 253 #define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
 254 #define __ClearPageDirty(page)  __clear_bit(PG_dirty, &(page)->flags)
 255 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 256
 257 #define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
 258 #define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
 259 #define ClearPageLRU(page)      clear_bit(PG_lru, &(page)->flags)
 260 #define __ClearPageLRU(page)    __clear_bit(PG_lru, &(page)->flags)
 261
 262 #define PageActive(page)        test_bit(PG_active, &(page)->flags)
 263 #define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
 264 #define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
 265 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
 266
 267 #define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
 268 #define __SetPageSlab(page)     __set_bit(PG_slab, &(page)->flags)
 269 #define __ClearPageSlab(page)   __clear_bit(PG_slab, &(page)->flags)
 270
 271 #ifdef CONFIG_HIGHMEM
 272 #define PageHighMem(page)       is_highmem(page_zone(page))
 273 #else
 274 #define PageHighMem(page)       0 /* needed to optimize away at compile time */
 275 #endif
 276
 277 #define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
 278 #define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
 279 #define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
 280
 281 #define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
 282 #define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
 283 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
 284 #define __ClearPageReserved(page)       __clear_bit(PG_reserved, &(page)->flags)
 285
 286 #define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
 287 #define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
 288 #define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
 289 #define __SetPagePrivate(page)  __set_bit(PG_private, &(page)->flags)
 290 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
 291
 292 #define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
 293 #define SetPageWriteback(page)                                          \
 294         do {                                                            \
 295                 if (!test_and_set_bit(PG_writeback,                     \
 296                                 &(page)->flags))                        \
 297                         inc_page_state(nr_writeback);                   \
 298         } while (0)
 299 #define TestSetPageWriteback(page)                                      \
 300         ({                                                              \
 301                 int ret;                                                \
 302                 ret = test_and_set_bit(PG_writeback,                    \
 303                                         &(page)->flags);                \
 304                 if (!ret)                                               \
 305                         inc_page_state(nr_writeback);                   \
 306                 ret;                                                    \
 307         })
 308 #define ClearPageWriteback(page)                                        \
 309         do {                                                            \
 310                 if (test_and_clear_bit(PG_writeback,                    \
 311                                 &(page)->flags))                        \
 312                         dec_page_state(nr_writeback);                   \
 313         } while (0)
 314 #define TestClearPageWriteback(page)                                    \
 315         ({                                                              \
 316                 int ret;                                                \
 317                 ret = test_and_clear_bit(PG_writeback,                  \
 318                                 &(page)->flags);                        \
 319                 if (ret)                                                \
 320                         dec_page_state(nr_writeback);                   \
 321                 ret;                                                    \
 322         })
 323
 324 #define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
 325 #define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
 326 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
 327 #define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
 328 #define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
 329
 330 #define PageNosaveFree(page)    test_bit(PG_nosave_free, &(page)->flags)
 331 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
 332 #define ClearPageNosaveFree(page)               clear_bit(PG_nosave_free, &(page)->flags)
 333
 334 #define PageBuddy(page)         test_bit(PG_buddy, &(page)->flags)
 335 #define __SetPageBuddy(page)    __set_bit(PG_buddy, &(page)->flags)
 336 #define __ClearPageBuddy(page)  __clear_bit(PG_buddy, &(page)->flags)
 337
 338 #define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
 339 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
 340 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
 341
 342 #define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
 343 #define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
 344 #define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
 345 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
 346
 347 #define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
 348 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
 349 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
 350
 351 #ifdef CONFIG_SWAP
 352 #define PageSwapCache(page)     test_bit(PG_swapcache, &(page)->flags)
 353 #define SetPageSwapCache(page)  set_bit(PG_swapcache, &(page)->flags)
 354 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
 355 #else
 356 #define PageSwapCache(page)     0
 357 #endif
 358
 359 #define PageUncached(page)      test_bit(PG_uncached, &(page)->flags)
 360 #define SetPageUncached(page)   set_bit(PG_uncached, &(page)->flags)
 361 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
 362
 363 struct page;    /* forward declaration */
 364
 365 int test_clear_page_dirty(struct page *page);
 366 int test_clear_page_writeback(struct page *page);
 367 int test_set_page_writeback(struct page *page);
 368
 369 static inline void clear_page_dirty(struct page *page)
 370 {
 371         test_clear_page_dirty(page);
 372 }
 373
 374 static inline void set_page_writeback(struct page *page)
 375 {
 376         test_set_page_writeback(page);
 377 }
 378
 379 #endif  /* PAGE_FLAGS_H */