2 * Macros for manipulating and testing page->flags
8 #include <linux/types.h>
9 #ifndef __GENERATING_BOUNDS_H
10 #include <linux/mm_types.h>
11 #include <linux/bounds.h>
12 #endif /* !__GENERATING_BOUNDS_H */
15 * Various page->flags bits:
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)...
20 * The PG_private bitflag is set on pagecache pages if they contain filesystem
21 * specific data (which is normally at page->private). It can be used by
22 * private allocations for its own usage.
24 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
25 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
26 * is set before writeback starts and cleared when it finishes.
28 * PG_locked also pins a page in pagecache, and blocks truncation of the file
31 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
34 * PG_uptodate tells whether the page's contents is valid. When a read
35 * completes, the page becomes uptodate, unless a disk I/O error happened.
37 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
38 * file-backed pagecache (see mm/vmscan.c).
40 * PG_error is set to indicate that an I/O error occurred on this page.
42 * PG_arch_1 is an architecture specific page state bit. The generic code
43 * guarantees that this bit is cleared for a page when it first is entered into
46 * PG_highmem pages are not permanently mapped into the kernel virtual address
47 * space, they need to be kmapped separately for doing IO on the pages. The
48 * struct page (these bits with information) are always mapped into kernel
51 * PG_buddy is set to indicate that the page is free and in the buddy system
52 * (see mm/page_alloc.c).
57 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
58 * locked- and dirty-page accounting.
60 * The page flags field is split into two parts, the main flags area
61 * which extends from the low bits upwards, and the fields area which
62 * extends from the high bits downwards.
64 * | FIELD | ... | FLAGS |
68 * The fields area is reserved for fields mapping zone, node (for NUMA) and
69 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
70 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
73 PG_locked, /* Page is locked. Don't touch. */
81 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
82 PG_checked = PG_owner_priv_1, /* Used by some filesystems */
83 PG_pinned = PG_owner_priv_1, /* Xen pinned pagetable */
86 PG_private, /* If pagecache, has fs-private data */
87 PG_writeback, /* Page is under writeback */
88 PG_compound, /* A compound page */
89 PG_swapcache, /* Swap page: swp_entry_t in private */
90 PG_mappedtodisk, /* Has blocks allocated on-disk */
91 PG_reclaim, /* To be reclaimed asap */
92 /* PG_readahead is only used for file reads; PG_reclaim is only for writes */
93 PG_readahead = PG_reclaim, /* Reminder to do async read-ahead */
94 PG_buddy, /* Page is free, on buddy lists */
96 #if (BITS_PER_LONG > 32)
98 * 64-bit-only flags build down from bit 31
100 * 32 bit -------------------------------| FIELDS | FLAGS |
101 * 64 bit | FIELDS | ?????? FLAGS |
104 PG_uncached = 31, /* Page has been mapped as uncached */
109 #ifndef __GENERATING_BOUNDS_H
112 * Macros to create function definitions for page flags
114 #define TESTPAGEFLAG(uname, lname) \
115 static inline int Page##uname(struct page *page) \
116 { return test_bit(PG_##lname, &page->flags); }
118 #define SETPAGEFLAG(uname, lname) \
119 static inline void SetPage##uname(struct page *page) \
120 { set_bit(PG_##lname, &page->flags); }
122 #define CLEARPAGEFLAG(uname, lname) \
123 static inline void ClearPage##uname(struct page *page) \
124 { clear_bit(PG_##lname, &page->flags); }
126 #define __SETPAGEFLAG(uname, lname) \
127 static inline void __SetPage##uname(struct page *page) \
128 { __set_bit(PG_##lname, &page->flags); }
130 #define __CLEARPAGEFLAG(uname, lname) \
131 static inline void __ClearPage##uname(struct page *page) \
132 { __clear_bit(PG_##lname, &page->flags); }
134 #define TESTSETFLAG(uname, lname) \
135 static inline int TestSetPage##uname(struct page *page) \
136 { return test_and_set_bit(PG_##lname, &page->flags); }
138 #define TESTCLEARFLAG(uname, lname) \
139 static inline int TestClearPage##uname(struct page *page) \
140 { return test_and_clear_bit(PG_##lname, &page->flags); }
143 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
144 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
146 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
147 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
149 #define TESTSCFLAG(uname, lname) \
150 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
153 * Manipulation of page state flags
155 #define PageLocked(page) \
156 test_bit(PG_locked, &(page)->flags)
157 #define SetPageLocked(page) \
158 set_bit(PG_locked, &(page)->flags)
159 #define TestSetPageLocked(page) \
160 test_and_set_bit(PG_locked, &(page)->flags)
161 #define ClearPageLocked(page) \
162 clear_bit(PG_locked, &(page)->flags)
163 #define TestClearPageLocked(page) \
164 test_and_clear_bit(PG_locked, &(page)->flags)
166 #define PageError(page) test_bit(PG_error, &(page)->flags)
167 #define SetPageError(page) set_bit(PG_error, &(page)->flags)
168 #define ClearPageError(page) clear_bit(PG_error, &(page)->flags)
170 #define PageReferenced(page) test_bit(PG_referenced, &(page)->flags)
171 #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
172 #define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
173 #define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
175 static inline int PageUptodate(struct page *page)
177 int ret = test_bit(PG_uptodate, &(page)->flags);
180 * Must ensure that the data we read out of the page is loaded
181 * _after_ we've loaded page->flags to check for PageUptodate.
182 * We can skip the barrier if the page is not uptodate, because
183 * we wouldn't be reading anything from it.
185 * See SetPageUptodate() for the other side of the story.
193 static inline void __SetPageUptodate(struct page *page)
196 __set_bit(PG_uptodate, &(page)->flags);
198 page_clear_dirty(page);
202 static inline void SetPageUptodate(struct page *page)
205 if (!test_and_set_bit(PG_uptodate, &page->flags))
206 page_clear_dirty(page);
209 * Memory barrier must be issued before setting the PG_uptodate bit,
210 * so that all previous stores issued in order to bring the page
211 * uptodate are actually visible before PageUptodate becomes true.
213 * s390 doesn't need an explicit smp_wmb here because the test and
214 * set bit already provides full barriers.
217 set_bit(PG_uptodate, &(page)->flags);
221 #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
223 #define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
224 #define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)
225 #define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags)
226 #define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags)
227 #define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags)
228 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
230 #define PageLRU(page) test_bit(PG_lru, &(page)->flags)
231 #define SetPageLRU(page) set_bit(PG_lru, &(page)->flags)
232 #define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags)
233 #define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags)
235 #define PageActive(page) test_bit(PG_active, &(page)->flags)
236 #define SetPageActive(page) set_bit(PG_active, &(page)->flags)
237 #define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
238 #define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
240 #define PageSlab(page) test_bit(PG_slab, &(page)->flags)
241 #define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags)
242 #define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags)
244 #ifdef CONFIG_HIGHMEM
245 #define PageHighMem(page) is_highmem(page_zone(page))
247 #define PageHighMem(page) 0 /* needed to optimize away at compile time */
250 #define PageChecked(page) test_bit(PG_checked, &(page)->flags)
251 #define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
252 #define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
254 #define PagePinned(page) test_bit(PG_pinned, &(page)->flags)
255 #define SetPagePinned(page) set_bit(PG_pinned, &(page)->flags)
256 #define ClearPagePinned(page) clear_bit(PG_pinned, &(page)->flags)
258 #define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
259 #define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
260 #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
261 #define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags)
263 #define SetPagePrivate(page) set_bit(PG_private, &(page)->flags)
264 #define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags)
265 #define PagePrivate(page) test_bit(PG_private, &(page)->flags)
266 #define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
267 #define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
270 * Only test-and-set exist for PG_writeback. The unconditional operators are
271 * risky: they bypass page accounting.
273 #define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
274 #define TestSetPageWriteback(page) test_and_set_bit(PG_writeback, \
276 #define TestClearPageWriteback(page) test_and_clear_bit(PG_writeback, \
279 #define PageBuddy(page) test_bit(PG_buddy, &(page)->flags)
280 #define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags)
281 #define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags)
283 #define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags)
284 #define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
285 #define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
287 #define PageReadahead(page) test_bit(PG_readahead, &(page)->flags)
288 #define SetPageReadahead(page) set_bit(PG_readahead, &(page)->flags)
289 #define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
291 #define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
292 #define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
293 #define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
294 #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
296 #define PageCompound(page) test_bit(PG_compound, &(page)->flags)
297 #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
298 #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
301 * PG_reclaim is used in combination with PG_compound to mark the
302 * head and tail of a compound page
304 * PG_compound & PG_reclaim => Tail page
305 * PG_compound & ~PG_reclaim => Head page
308 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
310 #define PageTail(page) (((page)->flags & PG_head_tail_mask) \
311 == PG_head_tail_mask)
313 static inline void __SetPageTail(struct page *page)
315 page->flags |= PG_head_tail_mask;
318 static inline void __ClearPageTail(struct page *page)
320 page->flags &= ~PG_head_tail_mask;
323 #define PageHead(page) (((page)->flags & PG_head_tail_mask) \
324 == (1L << PG_compound))
325 #define __SetPageHead(page) __SetPageCompound(page)
326 #define __ClearPageHead(page) __ClearPageCompound(page)
329 #define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
330 #define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
331 #define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
333 #define PageSwapCache(page) 0
336 #define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
337 #define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
338 #define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
340 struct page; /* forward declaration */
342 extern void cancel_dirty_page(struct page *page, unsigned int account_size);
344 int test_clear_page_writeback(struct page *page);
345 int test_set_page_writeback(struct page *page);
347 static inline void set_page_writeback(struct page *page)
349 test_set_page_writeback(page);
352 #endif /* !__GENERATING_BOUNDS_H */
353 #endif /* PAGE_FLAGS_H */