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422 giacomo 1 
/*
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 * Macros for manipulating and testing page->flags
3 
 */
4 
 
5 
#ifndef PAGE_FLAGS_H
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#define PAGE_FLAGS_H
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#include <linux/percpu.h>
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#include <linux/cache.h>
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#include <asm/pgtable.h>
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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.
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 *
20 
 * During disk I/O, PG_locked is used. This bit is set before I/O and
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 * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
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 * 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
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 * 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,
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 * which is set any time the system accesses that page through the (mapping,
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 * index) hash table.  This referenced bit, together with the referenced bit
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 * in the page tables, is used to manipulate page->age and move the page across
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 * the active, inactive_dirty and inactive_clean lists.
32 
 *
33 
 * Note that the referenced bit, the page->lru list_head and the active,
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 * inactive_dirty and inactive_clean lists are protected by the
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 * zone->lru_lock, and *NOT* by the usual PG_locked bit!
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 *
37 
 * PG_error is set to indicate that an I/O error occurred on this page.
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 *
39 
 * PG_arch_1 is an architecture specific page state bit.  The generic code
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 * guarantees that this bit is cleared for a page when it first is entered into
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 * the page cache.
42 
 *
43 
 * PG_highmem pages are not permanently mapped into the kernel virtual address
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 * space, they need to be kmapped separately for doing IO on the pages.  The
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 * 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
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 * locked- and dirty-page accounting.  The top eight bits of page->flags are
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 * used for page->zone, so putting flag bits there doesn't work.
53 
 */
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#define PG_locked                0      /* Page is locked. Don't touch. */
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#define PG_error                 1
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#define PG_referenced            2
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#define PG_uptodate              3
58 
 
59 
#define PG_dirty                 4
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#define PG_lru                   5
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#define PG_active                6
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#define PG_slab                  7      /* slab debug (Suparna wants this) */
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64 
#define PG_highmem               8
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#define PG_checked               9      /* kill me in 2.5.<early>. */
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#define PG_arch_1               10
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#define PG_reserved             11
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69 
#define PG_private              12      /* Has something at ->private */
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#define PG_writeback            13      /* Page is under writeback */
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#define PG_nosave               14      /* Used for system suspend/resume */
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#define PG_chainlock            15      /* lock bit for ->pte_chain */
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74 
#define PG_direct               16      /* ->pte_chain points directly at pte */
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#define PG_mappedtodisk         17      /* Has blocks allocated on-disk */
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#define PG_reclaim              18      /* To be reclaimed asap */
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#define PG_compound             19      /* Part of a compound page */
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79 
 
80 
/*
81 
 * Global page accounting.  One instance per CPU.  Only unsigned longs are
82 
 * allowed.
83 
 */
84 
struct page_state {
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        unsigned long nr_dirty;         /* Dirty writeable pages */
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        unsigned long nr_writeback;     /* Pages under writeback */
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        unsigned long nr_unstable;      /* NFS unstable pages */
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        unsigned long nr_page_table_pages;/* Pages used for pagetables */
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        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 */
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        unsigned long pgpgout;          /* Disk writes */
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        unsigned long pswpin;           /* swap reads */
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        unsigned long pswpout;          /* swap writes */
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        unsigned long pgalloc;          /* page allocations */
102 
 
103 
        unsigned long pgfree;           /* page freeings */
104 
        unsigned long pgactivate;       /* pages moved inactive->active */
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        unsigned long pgdeactivate;     /* pages moved active->inactive */
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        unsigned long pgfault;          /* faults (major+minor) */
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        unsigned long pgmajfault;       /* faults (major only) */
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109 
        unsigned long pgscan;           /* pages scanned by page reclaim */
110 
        unsigned long pgrefill;         /* inspected in refill_inactive_zone */
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        unsigned long pgsteal;          /* total pages reclaimed */
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        unsigned long pginodesteal;     /* pages reclaimed via inode freeing */
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        unsigned long kswapd_steal;     /* pages reclaimed by kswapd */
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115 
        unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
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        unsigned long pageoutrun;       /* kswapd's calls to page reclaim */
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        unsigned long allocstall;       /* direct reclaim calls */
118 
        unsigned long pgrotated;        /* pages rotated to tail of the LRU */
119 
} ____cacheline_aligned;
120 
 
121 
DECLARE_PER_CPU(struct page_state, page_states);
122 
 
123 
extern void get_page_state(struct page_state *ret);
124 
extern void get_full_page_state(struct page_state *ret);
125 
 
126 
#define mod_page_state(member, delta)                                   \
127 
        do {                                                            \
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                unsigned long flags;                                    \
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                local_irq_save(flags);                                  \
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                __get_cpu_var(page_states).member += (delta);           \
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                local_irq_restore(flags);                               \
132 
        } while (0)
133 
 
134 
#define inc_page_state(member)  mod_page_state(member, 1UL)
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#define dec_page_state(member)  mod_page_state(member, 0UL - 1)
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#define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))
137 
 
138 
 
139 
/*
140 
 * Manipulation of page state flags
141 
 */
142 
#define PageLocked(page)                \
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                test_bit(PG_locked, &(page)->flags)
144 
#define SetPageLocked(page)             \
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                set_bit(PG_locked, &(page)->flags)
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#define TestSetPageLocked(page)         \
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                test_and_set_bit(PG_locked, &(page)->flags)
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#define ClearPageLocked(page)           \
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                clear_bit(PG_locked, &(page)->flags)
150 
#define TestClearPageLocked(page)       \
151 
                test_and_clear_bit(PG_locked, &(page)->flags)
152 
 
153 
#define PageError(page)         test_bit(PG_error, &(page)->flags)
154 
#define SetPageError(page)      set_bit(PG_error, &(page)->flags)
155 
#define ClearPageError(page)    clear_bit(PG_error, &(page)->flags)
156 
 
157 
#define PageReferenced(page)    test_bit(PG_referenced, &(page)->flags)
158 
#define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
159 
#define ClearPageReferenced(page)       clear_bit(PG_referenced, &(page)->flags)
160 
#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
161 
 
162 
#ifndef arch_set_page_uptodate
163 
#define arch_set_page_uptodate(page) do { } while (0)
164 
#endif
165 
 
166 
#define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
167 
#define SetPageUptodate(page) \
168 
        do {                                                            \
169 
                arch_set_page_uptodate(page);                           \
170 
                set_bit(PG_uptodate, &(page)->flags);                   \
171 
        } while (0)
172 
#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
173 
 
174 
#define PageDirty(page)         test_bit(PG_dirty, &(page)->flags)
175 
#define SetPageDirty(page)      set_bit(PG_dirty, &(page)->flags)
176 
#define TestSetPageDirty(page)  test_and_set_bit(PG_dirty, &(page)->flags)
177 
#define ClearPageDirty(page)    clear_bit(PG_dirty, &(page)->flags)
178 
#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
179 
 
180 
#define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
181 
#define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
182 
#define TestSetPageLRU(page)    test_and_set_bit(PG_lru, &(page)->flags)
183 
#define TestClearPageLRU(page)  test_and_clear_bit(PG_lru, &(page)->flags)
184 
 
185 
#define PageActive(page)        test_bit(PG_active, &(page)->flags)
186 
#define SetPageActive(page)     set_bit(PG_active, &(page)->flags)
187 
#define ClearPageActive(page)   clear_bit(PG_active, &(page)->flags)
188 
#define TestClearPageActive(page) test_and_clear_bit(PG_active, &(page)->flags)
189 
#define TestSetPageActive(page) test_and_set_bit(PG_active, &(page)->flags)
190 
 
191 
#define PageSlab(page)          test_bit(PG_slab, &(page)->flags)
192 
#define SetPageSlab(page)       set_bit(PG_slab, &(page)->flags)
193 
#define ClearPageSlab(page)     clear_bit(PG_slab, &(page)->flags)
194 
#define TestClearPageSlab(page) test_and_clear_bit(PG_slab, &(page)->flags)
195 
#define TestSetPageSlab(page)   test_and_set_bit(PG_slab, &(page)->flags)
196 
 
197 
#ifdef CONFIG_HIGHMEM
198 
#define PageHighMem(page)       test_bit(PG_highmem, &(page)->flags)
199 
#else
200 
#define PageHighMem(page)       0 /* needed to optimize away at compile time */
201 
#endif
202 
 
203 
#define PageChecked(page)       test_bit(PG_checked, &(page)->flags)
204 
#define SetPageChecked(page)    set_bit(PG_checked, &(page)->flags)
205 
#define ClearPageChecked(page)  clear_bit(PG_checked, &(page)->flags)
206 
 
207 
#define PageReserved(page)      test_bit(PG_reserved, &(page)->flags)
208 
#define SetPageReserved(page)   set_bit(PG_reserved, &(page)->flags)
209 
#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
210 
 
211 
#define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
212 
#define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
213 
#define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
214 
 
215 
#define PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
216 
#define SetPageWriteback(page)                                          \
217 
        do {                                                            \
218 
                if (!test_and_set_bit(PG_writeback,                     \
219 
                                &(page)->flags))                        \
220 
                        inc_page_state(nr_writeback);                   \
221 
        } while (0)
222 
#define TestSetPageWriteback(page)                                      \
223 
        ({                                                              \
224 
                int ret;                                                \
225 
                ret = test_and_set_bit(PG_writeback,                    \
226 
                                        &(page)->flags);                \
227 
                if (!ret)                                               \
228 
                        inc_page_state(nr_writeback);                   \
229 
                ret;                                                    \
230 
        })
231 
#define ClearPageWriteback(page)                                        \
232 
        do {                                                            \
233 
                if (test_and_clear_bit(PG_writeback,                    \
234 
                                &(page)->flags))                        \
235 
                        dec_page_state(nr_writeback);                   \
236 
        } while (0)
237 
#define TestClearPageWriteback(page)                                    \
238 
        ({                                                              \
239 
                int ret;                                                \
240 
                ret = test_and_clear_bit(PG_writeback,                  \
241 
                                &(page)->flags);                        \
242 
                if (ret)                                                \
243 
                        dec_page_state(nr_writeback);                   \
244 
                ret;                                                    \
245 
        })
246 
 
247 
#define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
248 
#define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
249 
#define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
250 
#define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
251 
#define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)
252 
 
253 
#define PageDirect(page)        test_bit(PG_direct, &(page)->flags)
254 
#define SetPageDirect(page)     set_bit(PG_direct, &(page)->flags)
255 
#define TestSetPageDirect(page) test_and_set_bit(PG_direct, &(page)->flags)
256 
#define ClearPageDirect(page)           clear_bit(PG_direct, &(page)->flags)
257 
#define TestClearPageDirect(page)       test_and_clear_bit(PG_direct, &(page)->flags)
258 
 
259 
#define PageMappedToDisk(page)  test_bit(PG_mappedtodisk, &(page)->flags)
260 
#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
261 
#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
262 
 
263 
#define PageReclaim(page)       test_bit(PG_reclaim, &(page)->flags)
264 
#define SetPageReclaim(page)    set_bit(PG_reclaim, &(page)->flags)
265 
#define ClearPageReclaim(page)  clear_bit(PG_reclaim, &(page)->flags)
266 
#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
267 
 
268 
#define PageCompound(page)      test_bit(PG_compound, &(page)->flags)
269 
#define SetPageCompound(page)   set_bit(PG_compound, &(page)->flags)
270 
#define ClearPageCompound(page) clear_bit(PG_compound, &(page)->flags)
271 
 
272 
/*
273 
 * The PageSwapCache predicate doesn't use a PG_flag at this time,
274 
 * but it may again do so one day.
275 
 */
276 
#ifdef CONFIG_SWAP
277 
extern struct address_space swapper_space;
278 
#define PageSwapCache(page) ((page)->mapping == &swapper_space)
279 
#else
280 
#define PageSwapCache(page) 0
281 
#endif
282 
 
283 
struct page;    /* forward declaration */
284 
 
285 
int test_clear_page_dirty(struct page *page);
286 
 
287 
static inline void clear_page_dirty(struct page *page)
288 
{
289 
        test_clear_page_dirty(page);
290 
}
291 
 
292 
#endif  /* PAGE_FLAGS_H */