2 * Macros for manipulating and testing page->flags
8 #include <linux/types.h>
9 #include <linux/mm_types.h>
12 * Various page->flags bits:
14 * PG_reserved is set for special pages, which can never be swapped out. Some
15 * of them might not even exist (eg empty_bad_page)...
17 * The PG_private bitflag is set on pagecache pages if they contain filesystem
18 * specific data (which is normally at page->private). It can be used by
19 * private allocations for its own usage.
21 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
22 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
23 * is set before writeback starts and cleared when it finishes.
25 * PG_locked also pins a page in pagecache, and blocks truncation of the file
28 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
31 * PG_uptodate tells whether the page's contents is valid. When a read
32 * completes, the page becomes uptodate, unless a disk I/O error happened.
34 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
35 * file-backed pagecache (see mm/vmscan.c).
37 * PG_error is set to indicate that an I/O error occurred on this page.
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
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
48 * PG_buddy is set to indicate that the page is free and in the buddy system
49 * (see mm/page_alloc.c).
54 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
55 * locked- and dirty-page accounting.
57 * The page flags field is split into two parts, the main flags area
58 * which extends from the low bits upwards, and the fields area which
59 * extends from the high bits downwards.
61 * | FIELD | ... | FLAGS |
65 * The fields area is reserved for fields mapping zone, node and SPARSEMEM
66 * section. The boundry between these two areas is defined by
67 * FLAGS_RESERVED which defines the width of the fields section
68 * (see linux/mmzone.h). New flags must _not_ overlap with this area.
70 #define PG_locked 0 /* Page is locked. Don't touch. */
72 #define PG_referenced 2
78 #define PG_slab 7 /* slab debug (Suparna wants this) */
80 #define PG_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/
82 #define PG_reserved 10
83 #define PG_private 11 /* If pagecache, has fs-private data */
85 #define PG_writeback 12 /* Page is under writeback */
86 #define PG_readahead 13 /* Reminder to do async read-ahead */
87 #define PG_compound 14 /* Part of a compound page */
88 #define PG_swapcache 15 /* Swap page: swp_entry_t in private */
90 #define PG_mappedtodisk 16 /* Has blocks allocated on-disk */
91 #define PG_reclaim 17 /* To be reclaimed asap */
92 #define PG_buddy 19 /* Page is free, on buddy lists */
94 /* PG_owner_priv_1 users should have descriptive aliases */
95 #define PG_checked PG_owner_priv_1 /* Used by some filesystems */
96 #define PG_pinned PG_owner_priv_1 /* Xen pinned pagetable */
98 #if (BITS_PER_LONG > 32)
100 * 64-bit-only flags build down from bit 31
102 * 32 bit -------------------------------| FIELDS | FLAGS |
103 * 64 bit | FIELDS | ?????? FLAGS |
106 #define PG_uncached 31 /* Page has been mapped as uncached */
110 * Manipulation of page state flags
112 #define PageLocked(page) \
113 test_bit(PG_locked, &(page)->flags)
114 #define SetPageLocked(page) \
115 set_bit(PG_locked, &(page)->flags)
116 #define TestSetPageLocked(page) \
117 test_and_set_bit(PG_locked, &(page)->flags)
118 #define ClearPageLocked(page) \
119 clear_bit(PG_locked, &(page)->flags)
120 #define TestClearPageLocked(page) \
121 test_and_clear_bit(PG_locked, &(page)->flags)
123 #define PageError(page) test_bit(PG_error, &(page)->flags)
124 #define SetPageError(page) set_bit(PG_error, &(page)->flags)
125 #define ClearPageError(page) clear_bit(PG_error, &(page)->flags)
127 #define PageReferenced(page) test_bit(PG_referenced, &(page)->flags)
128 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
129 #define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
130 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
132 #define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags)
134 static inline void SetPageUptodate(struct page *page)
136 if (!test_and_set_bit(PG_uptodate, &page->flags))
137 page_clear_dirty(page);
140 #define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags)
142 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
144 #define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
145 #define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)
146 #define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags)
147 #define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags)
148 #define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags)
149 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
151 #define PageLRU(page) test_bit(PG_lru, &(page)->flags)
152 #define SetPageLRU(page) set_bit(PG_lru, &(page)->flags)
153 #define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags)
154 #define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags)
156 #define PageActive(page) test_bit(PG_active, &(page)->flags)
157 #define SetPageActive(page) set_bit(PG_active, &(page)->flags)
158 #define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
159 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
161 #define PageSlab(page) test_bit(PG_slab, &(page)->flags)
162 #define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags)
163 #define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags)
165 #ifdef CONFIG_HIGHMEM
166 #define PageHighMem(page) is_highmem(page_zone(page))
168 #define PageHighMem(page) 0 /* needed to optimize away at compile time */
171 #define PageChecked(page) test_bit(PG_checked, &(page)->flags)
172 #define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
173 #define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
175 #define PagePinned(page) test_bit(PG_pinned, &(page)->flags)
176 #define SetPagePinned(page) set_bit(PG_pinned, &(page)->flags)
177 #define ClearPagePinned(page) clear_bit(PG_pinned, &(page)->flags)
179 #define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
180 #define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
181 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
182 #define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags)
184 #define SetPagePrivate(page) set_bit(PG_private, &(page)->flags)
185 #define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags)
186 #define PagePrivate(page) test_bit(PG_private, &(page)->flags)
187 #define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
188 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
190 #define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
191 #define SetPageWriteback(page) \
193 if (!test_and_set_bit(PG_writeback, \
195 inc_zone_page_state(page, NR_WRITEBACK); \
197 #define TestSetPageWriteback(page) \
200 ret = test_and_set_bit(PG_writeback, \
203 inc_zone_page_state(page, NR_WRITEBACK); \
206 #define ClearPageWriteback(page) \
208 if (test_and_clear_bit(PG_writeback, \
210 dec_zone_page_state(page, NR_WRITEBACK); \
212 #define TestClearPageWriteback(page) \
215 ret = test_and_clear_bit(PG_writeback, \
218 dec_zone_page_state(page, NR_WRITEBACK); \
222 #define PageBuddy(page) test_bit(PG_buddy, &(page)->flags)
223 #define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags)
224 #define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags)
226 #define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags)
227 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
228 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
230 #define PageReadahead(page) test_bit(PG_readahead, &(page)->flags)
231 #define SetPageReadahead(page) set_bit(PG_readahead, &(page)->flags)
232 #define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
234 #define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
235 #define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
236 #define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
237 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
239 #define PageCompound(page) test_bit(PG_compound, &(page)->flags)
240 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
241 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
244 * PG_reclaim is used in combination with PG_compound to mark the
245 * head and tail of a compound page
247 * PG_compound & PG_reclaim => Tail page
248 * PG_compound & ~PG_reclaim => Head page
251 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
253 #define PageTail(page) ((page->flags & PG_head_tail_mask) \
254 == PG_head_tail_mask)
256 static inline void __SetPageTail(struct page *page)
258 page->flags |= PG_head_tail_mask;
261 static inline void __ClearPageTail(struct page *page)
263 page->flags &= ~PG_head_tail_mask;
266 #define PageHead(page) ((page->flags & PG_head_tail_mask) \
267 == (1L << PG_compound))
268 #define __SetPageHead(page) __SetPageCompound(page)
269 #define __ClearPageHead(page) __ClearPageCompound(page)
272 #define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
273 #define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
274 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
276 #define PageSwapCache(page) 0
279 #define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
280 #define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
281 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
283 struct page; /* forward declaration */
285 extern void cancel_dirty_page(struct page *page, unsigned int account_size);
287 int test_clear_page_writeback(struct page *page);
288 int test_set_page_writeback(struct page *page);
290 static inline void set_page_writeback(struct page *page)
292 test_set_page_writeback(page);
295 #endif /* PAGE_FLAGS_H */