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 <linux/types.h>
  11
  12 #include <asm/pgtable.h>
  13
  14 /*
  15  * Various page->flags bits:
  16  *
  17  * PG_reserved is set for special pages, which can never be swapped out. Some
  18  * of them might not even exist (eg empty_bad_page)...
  19  *
  20  * The PG_private bitflag is set if page->private contains a valid value.
  21  *
  22  * During disk I/O, PG_locked is used. This bit is set before I/O and
  23  * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
  24  * waiting for the I/O on this page to complete.
  25  *
  26  * PG_uptodate tells whether the page's contents is valid.  When a read
  27  * completes, the page becomes uptodate, unless a disk I/O error happened.
  28  *
  29  * For choosing which pages to swap out, inode pages carry a PG_referenced bit,
  30  * which is set any time the system accesses that page through the (mapping,
  31  * index) hash table.  This referenced bit, together with the referenced bit
  32  * in the page tables, is used to manipulate page->age and move the page across
  33  * the active, inactive_dirty and inactive_clean lists.
  34  *
  35  * Note that the referenced bit, the page->lru list_head and the active,
  36  * inactive_dirty and inactive_clean lists are protected by the
  37  * zone->lru_lock, and *NOT* by the usual PG_locked bit!
  38  *
  39  * PG_error is set to indicate that an I/O error occurred on this page.
  40  *
  41  * PG_arch_1 is an architecture specific page state bit.  The generic code
  42  * guarantees that this bit is cleared for a page when it first is entered into
  43  * the page cache.
  44  *
  45  * PG_highmem pages are not permanently mapped into the kernel virtual address
  46  * space, they need to be kmapped separately for doing IO on the pages.  The
  47  * struct page (these bits with information) are always mapped into kernel
  48  * address space...
  49  */
  50
  51 /*
  52  * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
  53  * locked- and dirty-page accounting.
  54  *
  55  * The page flags field is split into two parts, the main flags area
  56  * which extends from the low bits upwards, and the fields area which
  57  * extends from the high bits downwards.
  58  *
  59  *  | FIELD | ... | FLAGS |
  60  *  N-1     ^             0
  61  *          (N-FLAGS_RESERVED)
  62  *
  63  * The fields area is reserved for fields mapping zone, node and SPARSEMEM
  64  * section.  The boundry between these two areas is defined by
  65  * FLAGS_RESERVED which defines the width of the fields section
  66  * (see linux/mmzone.h).  New flags must _not_ overlap with this area.
  67  */
  68 #define PG_locked                0      /* Page is locked. Don't touch. */
  69 #define PG_error                 1
  70 #define PG_referenced            2
  71 #define PG_uptodate              3
  72
  73 #define PG_dirty                 4
  74 #define PG_lru                   5
  75 #define PG_active                6
  76 #define PG_slab                  7      /* slab debug (Suparna wants this) */
  77
  78 #define PG_checked               8      /* kill me in 2.5.<early>. */
  79 #define PG_arch_1                9
  80 #define PG_reserved             10
  81 #define PG_private              11      /* Has something at ->private */
  82
  83 #define PG_writeback            12      /* Page is under writeback */
  84 #define PG_nosave               13      /* Used for system suspend/resume */
  85 #define PG_compound             14      /* Part of a compound page */
  86 #define PG_swapcache            15      /* Swap page: swp_entry_t in private */
  87
  88 #define PG_mappedtodisk         16      /* Has blocks allocated on-disk */
  89 #define PG_reclaim              17      /* To be reclaimed asap */
  90 #define PG_nosave_free          18      /* Free, should not be written */
  91 #define PG_buddy                19      /* Page is free, on buddy lists */
  92
  93
  94 #if (BITS_PER_LONG > 32)
  95 /*
  96  * 64-bit-only flags build down from bit 31
  97  *
  98  * 32 bit  -------------------------------| FIELDS |       FLAGS         |
  99  * 64 bit  |           FIELDS             | ??????         FLAGS         |
 100  *         63                            32                              0
 101  */
 102 #define PG_uncached             31      /* Page has been mapped as uncached */
 103 #endif
 104
 105 /*
 106  * Global page accounting.  One instance per CPU.  Only unsigned longs are
 107  * allowed.
 108  *
 109  * - Fields can be modified with xxx_page_state and xxx_page_state_zone at
 110  * any time safely (which protects the instance from modification by
 111  * interrupt.
 112  * - The __xxx_page_state variants can be used safely when interrupts are
 113  * disabled.
 114  * - The __xxx_page_state variants can be used if the field is only
 115  * modified from process context and protected from preemption, or only
 116  * modified from interrupt context.  In this case, the field should be
 117  * commented here.
 118  */
 119 struct page_state {
 120         unsigned long nr_dirty;         /* Dirty writeable pages */
 121         unsigned long nr_writeback;     /* Pages under writeback */
 122         unsigned long nr_unstable;      /* NFS unstable pages */
 123         unsigned long nr_page_table_pages;/* Pages used for pagetables */
 124         unsigned long nr_mapped;        /* mapped into pagetables.
 125                                          * only modified from process context */
 126         unsigned long nr_slab;          /* In slab */
 127 #define GET_PAGE_STATE_LAST nr_slab
 128
 129         /*
 130          * The below are zeroed by get_page_state().  Use get_full_page_state()
 131          * to add up all these.
 132          */
 133         unsigned long pgpgin;           /* Disk reads */
 134         unsigned long pgpgout;          /* Disk writes */
 135         unsigned long pswpin;           /* swap reads */
 136         unsigned long pswpout;          /* swap writes */
 137
 138         unsigned long pgalloc_high;     /* page allocations */
 139         unsigned long pgalloc_normal;
 140         unsigned long pgalloc_dma32;
 141         unsigned long pgalloc_dma;
 142
 143         unsigned long pgfree;           /* page freeings */
 144         unsigned long pgactivate;       /* pages moved inactive->active */
 145         unsigned long pgdeactivate;     /* pages moved active->inactive */
 146
 147         unsigned long pgfault;          /* faults (major+minor) */
 148         unsigned long pgmajfault;       /* faults (major only) */
 149
 150         unsigned long pgrefill_high;    /* inspected in refill_inactive_zone */
 151         unsigned long pgrefill_normal;
 152         unsigned long pgrefill_dma32;
 153         unsigned long pgrefill_dma;
 154
 155         unsigned long pgsteal_high;     /* total highmem pages reclaimed */
 156         unsigned long pgsteal_normal;
 157         unsigned long pgsteal_dma32;
 158         unsigned long pgsteal_dma;
 159
 160         unsigned long pgscan_kswapd_high;/* total highmem pages scanned */
 161         unsigned long pgscan_kswapd_normal;
 162         unsigned long pgscan_kswapd_dma32;
 163         unsigned long pgscan_kswapd_dma;
 164
 165         unsigned long pgscan_direct_high;/* total highmem pages scanned */
 166         unsigned long pgscan_direct_normal;
 167         unsigned long pgscan_direct_dma32;
 168         unsigned long pgscan_direct_dma;
 169
 170         unsigned long pginodesteal;     /* pages reclaimed via inode freeing */
 171         unsigned long slabs_scanned;    /* slab objects scanned */
 172         unsigned long kswapd_steal;     /* pages reclaimed by kswapd */
 173         unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
 174         unsigned long pageoutrun;       /* kswapd's calls to page reclaim */
 175         unsigned long allocstall;       /* direct reclaim calls */
 176
 177         unsigned long pgrotated;        /* pages rotated to tail of the LRU */
 178         unsigned long nr_bounce;        /* pages for bounce buffers */
 179 };
 180
 181 extern void get_page_state(struct page_state *ret);
 182 extern void get_page_state_node(struct page_state *ret, int node);
 183 extern void get_full_page_state(struct page_state *ret);
 184 extern unsigned long read_page_state_offset(unsigned long offset);
 185 extern void mod_page_state_offset(unsigned long offset, unsigned long delta);
 186 extern void __mod_page_state_offset(unsigned long offset, unsigned long delta);
 187
 188 #define read_page_state(member) \
 189         read_page_state_offset(offsetof(struct page_state, member))
 190
 191 #define mod_page_state(member, delta)   \
 192         mod_page_state_offset(offsetof(struct page_state, member), (delta))
 193
 194 #define __mod_page_state(member, delta) \
 195         __mod_page_state_offset(offsetof(struct page_state, member), (delta))
 196
 197 #define inc_page_state(member)          mod_page_state(member, 1UL)
 198 #define dec_page_state(member)          mod_page_state(member, 0UL - 1)
 199 #define add_page_state(member,delta)    mod_page_state(member, (delta))
 200 #define sub_page_state(member,delta)    mod_page_state(member, 0UL - (delta))
 201
 202 #define __inc_page_state(member)        __mod_page_state(member, 1UL)
 203 #define __dec_page_state(member)        __mod_page_state(member, 0UL - 1)
 204 #define __add_page_state(member,delta)  __mod_page_state(member, (delta))
 205 #define __sub_page_state(member,delta)  __mod_page_state(member, 0UL - (delta))
 206
 207 #define page_state(member) (*__page_state(offsetof(struct page_state, member)))
 208
 209 #define state_zone_offset(zone, member)                                 \
 210 ({                                                                      \
 211         unsigned offset;                                                \
 212         if (is_highmem(zone))                                           \
 213                 offset = offsetof(struct page_state, member##_high);    \
 214         else if (is_normal(zone))                                       \
 215                 offset = offsetof(struct page_state, member##_normal);  \
 216         else if (is_dma32(zone))                                        \
 217                 offset = offsetof(struct page_state, member##_dma32);   \
 218         else                                                            \
 219                 offset = offsetof(struct page_state, member##_dma);     \
 220         offset;                                                         \
 221 })
 222
 223 #define __mod_page_state_zone(zone, member, delta)                      \
 224  do {                                                                   \
 225         __mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
 226  } while (0)
 227
 228 #define mod_page_state_zone(zone, member, delta)                        \
 229  do {                                                                   \
 230         mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
 231  } while (0)
 232
 233 /*
 234  * Manipulation of page state flags
 235  */
 236 #define PageLocked(page)                \
 237                 test_bit(PG_locked, &(page)->flags)
 238 #define SetPageLocked(page)             \
 239                 set_bit(PG_locked, &(page)->flags)
 240 #define TestSetPageLocked(page)         \
 241                 test_and_set_bit(PG_locked, &(page)->flags)
 242 #define ClearPageLocked(page)           \
 243                 clear_bit(PG_locked, &(page)->flags)
 244 #define TestClearPageLocked(page)       \
 245                 test_and_clear_bit(PG_locked, &(page)->flags)
 246
 247 #define PageError(page)         test_bit(PG_error, &(page)->flags)
 248 #define SetPageError(page)      set_bit(PG_error, &(page)->flags)
 249 #define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
 250
 251 #define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
 252 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
 253 #define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
 254 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
 255
 256 #define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
 257 #ifndef SetPageUptodate
 258 #define SetPageUptodate(page)   set_bit(PG_uptodate, &(page)->flags)
 259 #endif
 260 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
 261
 262 #define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
 263 #define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
 264 #define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
 265 #define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
 266 #define __ClearPageDirty(page)  __clear_bit(PG_dirty, &(page)->flags)
 267 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 268
 269 #define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
 270 #define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
 271 #define ClearPageLRU(page)      clear_bit(PG_lru, &(page)->flags)
 272 #define __ClearPageLRU(page)    __clear_bit(PG_lru, &(page)->flags)
 273
 274 #define PageActive(page)        test_bit(PG_active, &(page)->flags)
 275 #define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
 276 #define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
 277 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
 278
 279 #define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
 280 #define __SetPageSlab(page)     __set_bit(PG_slab, &(page)->flags)
 281 #define __ClearPageSlab(page)   __clear_bit(PG_slab, &(page)->flags)
 282
 283 #ifdef CONFIG_HIGHMEM
 284 #define PageHighMem(page)       is_highmem(page_zone(page))
 285 #else
 286 #define PageHighMem(page)       0 /* needed to optimize away at compile time */
 287 #endif
 288
 289 #define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
 290 #define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
 291 #define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
 292
 293 #define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
 294 #define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
 295 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
 296 #define __ClearPageReserved(page)       __clear_bit(PG_reserved, &(page)->flags)
 297
 298 #define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
 299 #define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
 300 #define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
 301 #define __SetPagePrivate(page)  __set_bit(PG_private, &(page)->flags)
 302 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
 303
 304 #define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
 305 #define SetPageWriteback(page)                                          \
 306         do {                                                            \
 307                 if (!test_and_set_bit(PG_writeback,                     \
 308                                 &(page)->flags))                        \
 309                         inc_page_state(nr_writeback);                   \
 310         } while (0)
 311 #define TestSetPageWriteback(page)                                      \
 312         ({                                                              \
 313                 int ret;                                                \
 314                 ret = test_and_set_bit(PG_writeback,                    \
 315                                         &(page)->flags);                \
 316                 if (!ret)                                               \
 317                         inc_page_state(nr_writeback);                   \
 318                 ret;                                                    \
 319         })
 320 #define ClearPageWriteback(page)                                        \
 321         do {                                                            \
 322                 if (test_and_clear_bit(PG_writeback,                    \
 323                                 &(page)->flags))                        \
 324                         dec_page_state(nr_writeback);                   \
 325         } while (0)
 326 #define TestClearPageWriteback(page)                                    \
 327         ({                                                              \
 328                 int ret;                                                \
 329                 ret = test_and_clear_bit(PG_writeback,                  \
 330                                 &(page)->flags);                        \
 331                 if (ret)                                                \
 332                         dec_page_state(nr_writeback);                   \
 333                 ret;                                                    \
 334         })
 335
 336 #define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
 337 #define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
 338 #define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
 339 #define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
 340 #define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
 341
 342 #define PageNosaveFree(page)    test_bit(PG_nosave_free, &(page)->flags)
 343 #define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
 344 #define ClearPageNosaveFree(page)               clear_bit(PG_nosave_free, &(page)->flags)
 345
 346 #define PageBuddy(page)         test_bit(PG_buddy, &(page)->flags)
 347 #define __SetPageBuddy(page)    __set_bit(PG_buddy, &(page)->flags)
 348 #define __ClearPageBuddy(page)  __clear_bit(PG_buddy, &(page)->flags)
 349
 350 #define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
 351 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
 352 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
 353
 354 #define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
 355 #define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
 356 #define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
 357 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
 358
 359 #define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
 360 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
 361 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
 362
 363 #ifdef CONFIG_SWAP
 364 #define PageSwapCache(page)     test_bit(PG_swapcache, &(page)->flags)
 365 #define SetPageSwapCache(page)  set_bit(PG_swapcache, &(page)->flags)
 366 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
 367 #else
 368 #define PageSwapCache(page)     0
 369 #endif
 370
 371 #define PageUncached(page)      test_bit(PG_uncached, &(page)->flags)
 372 #define SetPageUncached(page)   set_bit(PG_uncached, &(page)->flags)
 373 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
 374
 375 struct page;    /* forward declaration */
 376
 377 int test_clear_page_dirty(struct page *page);
 378 int test_clear_page_writeback(struct page *page);
 379 int test_set_page_writeback(struct page *page);
 380
 381 static inline void clear_page_dirty(struct page *page)
 382 {
 383         test_clear_page_dirty(page);
 384 }
 385
 386 static inline void set_page_writeback(struct page *page)
 387 {
 388         test_set_page_writeback(page);
 389 }
 390
 391 #endif  /* PAGE_FLAGS_H */