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/types.h>
   9
  10/*
  11 * Various page->flags bits:
  12 *
  13 * PG_reserved is set for special pages, which can never be swapped out. Some
  14 * of them might not even exist (eg empty_bad_page)...
  15 *
  16 * The PG_private bitflag is set if page->private contains a valid value.
  17 *
  18 * During disk I/O, PG_locked is used. This bit is set before I/O and
  19 * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
  20 * waiting for the I/O on this page to complete.
  21 *
  22 * PG_uptodate tells whether the page's contents is valid.  When a read
  23 * completes, the page becomes uptodate, unless a disk I/O error happened.
  24 *
  25 * For choosing which pages to swap out, inode pages carry a PG_referenced bit,
  26 * which is set any time the system accesses that page through the (mapping,
  27 * index) hash table.  This referenced bit, together with the referenced bit
  28 * in the page tables, is used to manipulate page->age and move the page across
  29 * the active, inactive_dirty and inactive_clean lists.
  30 *
  31 * Note that the referenced bit, the page->lru list_head and the active,
  32 * inactive_dirty and inactive_clean lists are protected by the
  33 * zone->lru_lock, and *NOT* by the usual PG_locked bit!
  34 *
  35 * PG_error is set to indicate that an I/O error occurred on this page.
  36 *
  37 * PG_arch_1 is an architecture specific page state bit.  The generic code
  38 * guarantees that this bit is cleared for a page when it first is entered into
  39 * the page cache.
  40 *
  41 * PG_highmem pages are not permanently mapped into the kernel virtual address
  42 * space, they need to be kmapped separately for doing IO on the pages.  The
  43 * struct page (these bits with information) are always mapped into kernel
  44 * address space...
  45 */
  46
  47/*
  48 * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
  49 * locked- and dirty-page accounting.
  50 *
  51 * The page flags field is split into two parts, the main flags area
  52 * which extends from the low bits upwards, and the fields area which
  53 * extends from the high bits downwards.
  54 *
  55 *  | FIELD | ... | FLAGS |
  56 *  N-1     ^             0
  57 *          (N-FLAGS_RESERVED)
  58 *
  59 * The fields area is reserved for fields mapping zone, node and SPARSEMEM
  60 * section.  The boundry between these two areas is defined by
  61 * FLAGS_RESERVED which defines the width of the fields section
  62 * (see linux/mmzone.h).  New flags must _not_ overlap with this area.
  63 */
  64#define PG_locked                0      /* Page is locked. Don't touch. */
  65#define PG_error                 1
  66#define PG_referenced            2
  67#define PG_uptodate              3
  68
  69#define PG_dirty                 4
  70#define PG_lru                   5
  71#define PG_active                6
  72#define PG_slab                  7      /* slab debug (Suparna wants this) */
  73
  74#define PG_checked               8      /* kill me in 2.5.<early>. */
  75#define PG_arch_1                9
  76#define PG_reserved             10
  77#define PG_private              11      /* Has something at ->private */
  78
  79#define PG_writeback            12      /* Page is under writeback */
  80#define PG_nosave               13      /* Used for system suspend/resume */
  81#define PG_compound             14      /* Part of a compound page */
  82#define PG_swapcache            15      /* Swap page: swp_entry_t in private */
  83
  84#define PG_mappedtodisk         16      /* Has blocks allocated on-disk */
  85#define PG_reclaim              17      /* To be reclaimed asap */
  86#define PG_nosave_free          18      /* Free, should not be written */
  87#define PG_buddy                19      /* Page is free, on buddy lists */
  88
  89
  90#if (BITS_PER_LONG > 32)
  91/*
  92 * 64-bit-only flags build down from bit 31
  93 *
  94 * 32 bit  -------------------------------| FIELDS |       FLAGS         |
  95 * 64 bit  |           FIELDS             | ??????         FLAGS         |
  96 *         63                            32                              0
  97 */
  98#define PG_uncached             31      /* Page has been mapped as uncached */
  99#endif
 100
 101/*
 102 * Manipulation of page state flags
 103 */
 104#define PageLocked(page)                \
 105                test_bit(PG_locked, &(page)->flags)
 106#define SetPageLocked(page)             \
 107                set_bit(PG_locked, &(page)->flags)
 108#define TestSetPageLocked(page)         \
 109                test_and_set_bit(PG_locked, &(page)->flags)
 110#define ClearPageLocked(page)           \
 111                clear_bit(PG_locked, &(page)->flags)
 112#define TestClearPageLocked(page)       \
 113                test_and_clear_bit(PG_locked, &(page)->flags)
 114
 115#define PageError(page)         test_bit(PG_error, &(page)->flags)
 116#define SetPageError(page)      set_bit(PG_error, &(page)->flags)
 117#define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
 118
 119#define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
 120#define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
 121#define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
 122#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
 123
 124#define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
 125#ifdef CONFIG_S390
 126#define SetPageUptodate(_page) \
 127        do {                                                                  \
 128                struct page *__page = (_page);                                \
 129                if (!test_and_set_bit(PG_uptodate, &__page->flags))           \
 130                        page_test_and_clear_dirty(_page);                     \
 131        } while (0)
 132#else
 133#define SetPageUptodate(page)   set_bit(PG_uptodate, &(page)->flags)
 134#endif
 135#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
 136
 137#define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
 138#define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
 139#define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
 140#define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
 141#define __ClearPageDirty(page)  __clear_bit(PG_dirty, &(page)->flags)
 142#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 143
 144#define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
 145#define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
 146#define ClearPageLRU(page)      clear_bit(PG_lru, &(page)->flags)
 147#define __ClearPageLRU(page)    __clear_bit(PG_lru, &(page)->flags)
 148
 149#define PageActive(page)        test_bit(PG_active, &(page)->flags)
 150#define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
 151#define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
 152#define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
 153
 154#define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
 155#define __SetPageSlab(page)     __set_bit(PG_slab, &(page)->flags)
 156#define __ClearPageSlab(page)   __clear_bit(PG_slab, &(page)->flags)
 157
 158#ifdef CONFIG_HIGHMEM
 159#define PageHighMem(page)       is_highmem(page_zone(page))
 160#else
 161#define PageHighMem(page)       0 /* needed to optimize away at compile time */
 162#endif
 163
 164#define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
 165#define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
 166#define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
 167
 168#define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
 169#define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
 170#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
 171#define __ClearPageReserved(page)       __clear_bit(PG_reserved, &(page)->flags)
 172
 173#define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
 174#define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
 175#define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
 176#define __SetPagePrivate(page)  __set_bit(PG_private, &(page)->flags)
 177#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
 178
 179#define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
 180#define SetPageWriteback(page)                                          \
 181        do {                                                            \
 182                if (!test_and_set_bit(PG_writeback,                     \
 183                                &(page)->flags))                        \
 184                        inc_zone_page_state(page, NR_WRITEBACK);        \
 185        } while (0)
 186#define TestSetPageWriteback(page)                                      \
 187        ({                                                              \
 188                int ret;                                                \
 189                ret = test_and_set_bit(PG_writeback,                    \
 190                                        &(page)->flags);                \
 191                if (!ret)                                               \
 192                        inc_zone_page_state(page, NR_WRITEBACK);        \
 193                ret;                                                    \
 194        })
 195#define ClearPageWriteback(page)                                        \
 196        do {                                                            \
 197                if (test_and_clear_bit(PG_writeback,                    \
 198                                &(page)->flags))                        \
 199                        dec_zone_page_state(page, NR_WRITEBACK);        \
 200        } while (0)
 201#define TestClearPageWriteback(page)                                    \
 202        ({                                                              \
 203                int ret;                                                \
 204                ret = test_and_clear_bit(PG_writeback,                  \
 205                                &(page)->flags);                        \
 206                if (ret)                                                \
 207                        dec_zone_page_state(page, NR_WRITEBACK);        \
 208                ret;                                                    \
 209        })
 210
 211#define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
 212#define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
 213#define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
 214#define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
 215#define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
 216
 217#define PageNosaveFree(page)    test_bit(PG_nosave_free, &(page)->flags)
 218#define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
 219#define ClearPageNosaveFree(page)               clear_bit(PG_nosave_free, &(page)->flags)
 220
 221#define PageBuddy(page)         test_bit(PG_buddy, &(page)->flags)
 222#define __SetPageBuddy(page)    __set_bit(PG_buddy, &(page)->flags)
 223#define __ClearPageBuddy(page)  __clear_bit(PG_buddy, &(page)->flags)
 224
 225#define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
 226#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
 227#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
 228
 229#define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
 230#define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
 231#define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
 232#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
 233
 234#define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
 235#define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
 236#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
 237
 238#ifdef CONFIG_SWAP
 239#define PageSwapCache(page)     test_bit(PG_swapcache, &(page)->flags)
 240#define SetPageSwapCache(page)  set_bit(PG_swapcache, &(page)->flags)
 241#define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
 242#else
 243#define PageSwapCache(page)     0
 244#endif
 245
 246#define PageUncached(page)      test_bit(PG_uncached, &(page)->flags)
 247#define SetPageUncached(page)   set_bit(PG_uncached, &(page)->flags)
 248#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
 249
 250struct page;    /* forward declaration */
 251
 252int test_clear_page_dirty(struct page *page);
 253int test_clear_page_writeback(struct page *page);
 254int test_set_page_writeback(struct page *page);
 255
 256static inline void clear_page_dirty(struct page *page)
 257{
 258        test_clear_page_dirty(page);
 259}
 260
 261static inline void set_page_writeback(struct page *page)
 262{
 263        test_set_page_writeback(page);
 264}
 265
 266#endif  /* PAGE_FLAGS_H */
 267