LXR linux/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 */
 107struct 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
 169extern void get_page_state(struct page_state *ret);
 170extern void get_page_state_node(struct page_state *ret, int node);
 171extern void get_full_page_state(struct page_state *ret);
 172extern unsigned long read_page_state_offset(unsigned long offset);
 173extern void mod_page_state_offset(unsigned long offset, unsigned long delta);
 174extern 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
 363struct page;    /* forward declaration */
 364
 365int test_clear_page_dirty(struct page *page);
 366int test_clear_page_writeback(struct page *page);
 367int test_set_page_writeback(struct page *page);
 368
 369static inline void clear_page_dirty(struct page *page)
 370{
 371        test_clear_page_dirty(page);
 372}
 373
 374static inline void set_page_writeback(struct page *page)
 375{
 376        test_set_page_writeback(page);
 377}
 378
 379#endif  /* PAGE_FLAGS_H */
 380