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Commit | Line | Data |
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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 | #ifndef __GENERATING_BOUNDS_H | |
10 | #include <linux/mm_types.h> | |
11 | #include <linux/bounds.h> | |
12 | #endif /* !__GENERATING_BOUNDS_H */ | |
13 | ||
14 | /* | |
15 | * Various page->flags bits: | |
16 | * | |
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)... | |
19 | * | |
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. | |
23 | * | |
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. | |
27 | * | |
28 | * PG_locked also pins a page in pagecache, and blocks truncation of the file | |
29 | * while it is held. | |
30 | * | |
31 | * page_waitqueue(page) is a wait queue of all tasks waiting for the page | |
32 | * to become unlocked. | |
33 | * | |
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. | |
36 | * | |
37 | * PG_referenced, PG_reclaim are used for page reclaim for anonymous and | |
38 | * file-backed pagecache (see mm/vmscan.c). | |
39 | * | |
40 | * PG_error is set to indicate that an I/O error occurred on this page. | |
41 | * | |
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 | |
44 | * the page cache. | |
45 | * | |
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 | |
49 | * address space... | |
50 | * | |
51 | * PG_buddy is set to indicate that the page is free and in the buddy system | |
52 | * (see mm/page_alloc.c). | |
53 | * | |
54 | */ | |
55 | ||
56 | /* | |
57 | * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break | |
58 | * locked- and dirty-page accounting. | |
59 | * | |
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. | |
63 | * | |
64 | * | FIELD | ... | FLAGS | | |
65 | * N-1 ^ 0 | |
66 | * (NR_PAGEFLAGS) | |
67 | * | |
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). | |
71 | */ | |
72 | enum pageflags { | |
73 | PG_locked, /* Page is locked. Don't touch. */ | |
74 | PG_error, | |
75 | PG_referenced, | |
76 | PG_uptodate, | |
77 | PG_dirty, | |
78 | PG_lru, | |
79 | PG_active, | |
80 | PG_slab, | |
81 | PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/ | |
82 | PG_arch_1, | |
83 | PG_reserved, | |
84 | PG_private, /* If pagecache, has fs-private data */ | |
85 | PG_private_2, /* If pagecache, has fs aux data */ | |
86 | PG_writeback, /* Page is under writeback */ | |
87 | #ifdef CONFIG_PAGEFLAGS_EXTENDED | |
88 | PG_head, /* A head page */ | |
89 | PG_tail, /* A tail page */ | |
90 | #else | |
91 | PG_compound, /* A compound page */ | |
92 | #endif | |
93 | PG_swapcache, /* Swap page: swp_entry_t in private */ | |
94 | PG_mappedtodisk, /* Has blocks allocated on-disk */ | |
95 | PG_reclaim, /* To be reclaimed asap */ | |
96 | PG_buddy, /* Page is free, on buddy lists */ | |
97 | PG_swapbacked, /* Page is backed by RAM/swap */ | |
98 | PG_unevictable, /* Page is "unevictable" */ | |
99 | #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT | |
100 | PG_mlocked, /* Page is vma mlocked */ | |
101 | #endif | |
102 | #ifdef CONFIG_ARCH_USES_PG_UNCACHED | |
103 | PG_uncached, /* Page has been mapped as uncached */ | |
104 | #endif | |
105 | __NR_PAGEFLAGS, | |
106 | ||
107 | /* Filesystems */ | |
108 | PG_checked = PG_owner_priv_1, | |
109 | ||
110 | /* Two page bits are conscripted by FS-Cache to maintain local caching | |
111 | * state. These bits are set on pages belonging to the netfs's inodes | |
112 | * when those inodes are being locally cached. | |
113 | */ | |
114 | PG_fscache = PG_private_2, /* page backed by cache */ | |
115 | ||
116 | /* XEN */ | |
117 | PG_pinned = PG_owner_priv_1, | |
118 | PG_savepinned = PG_dirty, | |
119 | ||
120 | /* SLOB */ | |
121 | PG_slob_free = PG_private, | |
122 | ||
123 | /* SLUB */ | |
124 | PG_slub_frozen = PG_active, | |
125 | PG_slub_debug = PG_error, | |
126 | }; | |
127 | ||
128 | #ifndef __GENERATING_BOUNDS_H | |
129 | ||
130 | /* | |
131 | * Macros to create function definitions for page flags | |
132 | */ | |
133 | #define TESTPAGEFLAG(uname, lname) \ | |
134 | static inline int Page##uname(struct page *page) \ | |
135 | { return test_bit(PG_##lname, &page->flags); } | |
136 | ||
137 | #define SETPAGEFLAG(uname, lname) \ | |
138 | static inline void SetPage##uname(struct page *page) \ | |
139 | { set_bit(PG_##lname, &page->flags); } | |
140 | ||
141 | #define CLEARPAGEFLAG(uname, lname) \ | |
142 | static inline void ClearPage##uname(struct page *page) \ | |
143 | { clear_bit(PG_##lname, &page->flags); } | |
144 | ||
145 | #define __SETPAGEFLAG(uname, lname) \ | |
146 | static inline void __SetPage##uname(struct page *page) \ | |
147 | { __set_bit(PG_##lname, &page->flags); } | |
148 | ||
149 | #define __CLEARPAGEFLAG(uname, lname) \ | |
150 | static inline void __ClearPage##uname(struct page *page) \ | |
151 | { __clear_bit(PG_##lname, &page->flags); } | |
152 | ||
153 | #define TESTSETFLAG(uname, lname) \ | |
154 | static inline int TestSetPage##uname(struct page *page) \ | |
155 | { return test_and_set_bit(PG_##lname, &page->flags); } | |
156 | ||
157 | #define TESTCLEARFLAG(uname, lname) \ | |
158 | static inline int TestClearPage##uname(struct page *page) \ | |
159 | { return test_and_clear_bit(PG_##lname, &page->flags); } | |
160 | ||
161 | #define __TESTCLEARFLAG(uname, lname) \ | |
162 | static inline int __TestClearPage##uname(struct page *page) \ | |
163 | { return __test_and_clear_bit(PG_##lname, &page->flags); } | |
164 | ||
165 | #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ | |
166 | SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) | |
167 | ||
168 | #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ | |
169 | __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname) | |
170 | ||
171 | #define PAGEFLAG_FALSE(uname) \ | |
172 | static inline int Page##uname(struct page *page) \ | |
173 | { return 0; } | |
174 | ||
175 | #define TESTSCFLAG(uname, lname) \ | |
176 | TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname) | |
177 | ||
178 | #define SETPAGEFLAG_NOOP(uname) \ | |
179 | static inline void SetPage##uname(struct page *page) { } | |
180 | ||
181 | #define CLEARPAGEFLAG_NOOP(uname) \ | |
182 | static inline void ClearPage##uname(struct page *page) { } | |
183 | ||
184 | #define __CLEARPAGEFLAG_NOOP(uname) \ | |
185 | static inline void __ClearPage##uname(struct page *page) { } | |
186 | ||
187 | #define TESTCLEARFLAG_FALSE(uname) \ | |
188 | static inline int TestClearPage##uname(struct page *page) { return 0; } | |
189 | ||
190 | #define __TESTCLEARFLAG_FALSE(uname) \ | |
191 | static inline int __TestClearPage##uname(struct page *page) { return 0; } | |
192 | ||
193 | struct page; /* forward declaration */ | |
194 | ||
195 | TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked) | |
196 | PAGEFLAG(Error, error) | |
197 | PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced) | |
198 | PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty) | |
199 | PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru) | |
200 | PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active) | |
201 | TESTCLEARFLAG(Active, active) | |
202 | __PAGEFLAG(Slab, slab) | |
203 | PAGEFLAG(Checked, checked) /* Used by some filesystems */ | |
204 | PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */ | |
205 | PAGEFLAG(SavePinned, savepinned); /* Xen */ | |
206 | PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) | |
207 | PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) | |
208 | ||
209 | __PAGEFLAG(SlobFree, slob_free) | |
210 | ||
211 | __PAGEFLAG(SlubFrozen, slub_frozen) | |
212 | __PAGEFLAG(SlubDebug, slub_debug) | |
213 | ||
214 | /* | |
215 | * Private page markings that may be used by the filesystem that owns the page | |
216 | * for its own purposes. | |
217 | * - PG_private and PG_private_2 cause releasepage() and co to be invoked | |
218 | */ | |
219 | PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private) | |
220 | __CLEARPAGEFLAG(Private, private) | |
221 | PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2) | |
222 | PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1) | |
223 | ||
224 | /* | |
225 | * Only test-and-set exist for PG_writeback. The unconditional operators are | |
226 | * risky: they bypass page accounting. | |
227 | */ | |
228 | TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback) | |
229 | __PAGEFLAG(Buddy, buddy) | |
230 | PAGEFLAG(MappedToDisk, mappedtodisk) | |
231 | ||
232 | /* PG_readahead is only used for file reads; PG_reclaim is only for writes */ | |
233 | PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim) | |
234 | PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */ | |
235 | ||
236 | #ifdef CONFIG_HIGHMEM | |
237 | /* | |
238 | * Must use a macro here due to header dependency issues. page_zone() is not | |
239 | * available at this point. | |
240 | */ | |
241 | #define PageHighMem(__p) is_highmem(page_zone(__p)) | |
242 | #else | |
243 | PAGEFLAG_FALSE(HighMem) | |
244 | #endif | |
245 | ||
246 | #ifdef CONFIG_SWAP | |
247 | PAGEFLAG(SwapCache, swapcache) | |
248 | #else | |
249 | PAGEFLAG_FALSE(SwapCache) | |
250 | SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache) | |
251 | #endif | |
252 | ||
253 | PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable) | |
254 | TESTCLEARFLAG(Unevictable, unevictable) | |
255 | ||
256 | #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT | |
257 | #define MLOCK_PAGES 1 | |
258 | PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked) | |
259 | TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked) | |
260 | #else | |
261 | #define MLOCK_PAGES 0 | |
262 | PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked) | |
263 | TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked) | |
264 | #endif | |
265 | ||
266 | #ifdef CONFIG_ARCH_USES_PG_UNCACHED | |
267 | PAGEFLAG(Uncached, uncached) | |
268 | #else | |
269 | PAGEFLAG_FALSE(Uncached) | |
270 | #endif | |
271 | ||
272 | static inline int PageUptodate(struct page *page) | |
273 | { | |
274 | int ret = test_bit(PG_uptodate, &(page)->flags); | |
275 | ||
276 | /* | |
277 | * Must ensure that the data we read out of the page is loaded | |
278 | * _after_ we've loaded page->flags to check for PageUptodate. | |
279 | * We can skip the barrier if the page is not uptodate, because | |
280 | * we wouldn't be reading anything from it. | |
281 | * | |
282 | * See SetPageUptodate() for the other side of the story. | |
283 | */ | |
284 | if (ret) | |
285 | smp_rmb(); | |
286 | ||
287 | return ret; | |
288 | } | |
289 | ||
290 | static inline void __SetPageUptodate(struct page *page) | |
291 | { | |
292 | smp_wmb(); | |
293 | __set_bit(PG_uptodate, &(page)->flags); | |
294 | } | |
295 | ||
296 | static inline void SetPageUptodate(struct page *page) | |
297 | { | |
298 | #ifdef CONFIG_S390 | |
299 | if (!test_and_set_bit(PG_uptodate, &page->flags)) | |
300 | page_clear_dirty(page); | |
301 | #else | |
302 | /* | |
303 | * Memory barrier must be issued before setting the PG_uptodate bit, | |
304 | * so that all previous stores issued in order to bring the page | |
305 | * uptodate are actually visible before PageUptodate becomes true. | |
306 | * | |
307 | * s390 doesn't need an explicit smp_wmb here because the test and | |
308 | * set bit already provides full barriers. | |
309 | */ | |
310 | smp_wmb(); | |
311 | set_bit(PG_uptodate, &(page)->flags); | |
312 | #endif | |
313 | } | |
314 | ||
315 | CLEARPAGEFLAG(Uptodate, uptodate) | |
316 | ||
317 | extern void cancel_dirty_page(struct page *page, unsigned int account_size); | |
318 | ||
319 | int test_clear_page_writeback(struct page *page); | |
320 | int test_set_page_writeback(struct page *page); | |
321 | ||
322 | static inline void set_page_writeback(struct page *page) | |
323 | { | |
324 | test_set_page_writeback(page); | |
325 | } | |
326 | ||
327 | #ifdef CONFIG_PAGEFLAGS_EXTENDED | |
328 | /* | |
329 | * System with lots of page flags available. This allows separate | |
330 | * flags for PageHead() and PageTail() checks of compound pages so that bit | |
331 | * tests can be used in performance sensitive paths. PageCompound is | |
332 | * generally not used in hot code paths. | |
333 | */ | |
334 | __PAGEFLAG(Head, head) | |
335 | __PAGEFLAG(Tail, tail) | |
336 | ||
337 | static inline int PageCompound(struct page *page) | |
338 | { | |
339 | return page->flags & ((1L << PG_head) | (1L << PG_tail)); | |
340 | ||
341 | } | |
342 | #else | |
343 | /* | |
344 | * Reduce page flag use as much as possible by overlapping | |
345 | * compound page flags with the flags used for page cache pages. Possible | |
346 | * because PageCompound is always set for compound pages and not for | |
347 | * pages on the LRU and/or pagecache. | |
348 | */ | |
349 | TESTPAGEFLAG(Compound, compound) | |
350 | __PAGEFLAG(Head, compound) | |
351 | ||
352 | /* | |
353 | * PG_reclaim is used in combination with PG_compound to mark the | |
354 | * head and tail of a compound page. This saves one page flag | |
355 | * but makes it impossible to use compound pages for the page cache. | |
356 | * The PG_reclaim bit would have to be used for reclaim or readahead | |
357 | * if compound pages enter the page cache. | |
358 | * | |
359 | * PG_compound & PG_reclaim => Tail page | |
360 | * PG_compound & ~PG_reclaim => Head page | |
361 | */ | |
362 | #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) | |
363 | ||
364 | static inline int PageTail(struct page *page) | |
365 | { | |
366 | return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask); | |
367 | } | |
368 | ||
369 | static inline void __SetPageTail(struct page *page) | |
370 | { | |
371 | page->flags |= PG_head_tail_mask; | |
372 | } | |
373 | ||
374 | static inline void __ClearPageTail(struct page *page) | |
375 | { | |
376 | page->flags &= ~PG_head_tail_mask; | |
377 | } | |
378 | ||
379 | #endif /* !PAGEFLAGS_EXTENDED */ | |
380 | ||
381 | #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT | |
382 | #define __PG_MLOCKED (1 << PG_mlocked) | |
383 | #else | |
384 | #define __PG_MLOCKED 0 | |
385 | #endif | |
386 | ||
387 | /* | |
388 | * Flags checked when a page is freed. Pages being freed should not have | |
389 | * these flags set. It they are, there is a problem. | |
390 | */ | |
391 | #define PAGE_FLAGS_CHECK_AT_FREE \ | |
392 | (1 << PG_lru | 1 << PG_locked | \ | |
393 | 1 << PG_private | 1 << PG_private_2 | \ | |
394 | 1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \ | |
395 | 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ | |
396 | 1 << PG_unevictable | __PG_MLOCKED) | |
397 | ||
398 | /* | |
399 | * Flags checked when a page is prepped for return by the page allocator. | |
400 | * Pages being prepped should not have any flags set. It they are set, | |
401 | * there has been a kernel bug or struct page corruption. | |
402 | */ | |
403 | #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) | |
404 | ||
405 | #endif /* !__GENERATING_BOUNDS_H */ | |
406 | ||
407 | /** | |
408 | * page_has_private - Determine if page has private stuff | |
409 | * @page: The page to be checked | |
410 | * | |
411 | * Determine if a page has private stuff, indicating that release routines | |
412 | * should be invoked upon it. | |
413 | */ | |
414 | #define page_has_private(page) \ | |
415 | ((page)->flags & ((1 << PG_private) | \ | |
416 | (1 << PG_private_2))) | |
417 | ||
418 | #endif /* PAGE_FLAGS_H */ |