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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Macros for manipulating and testing page->flags | |
3 | */ | |
4 | ||
5 | #ifndef PAGE_FLAGS_H | |
6 | #define PAGE_FLAGS_H | |
7 | ||
f886ed44 | 8 | #include <linux/types.h> |
9223b419 | 9 | #ifndef __GENERATING_BOUNDS_H |
6d777953 | 10 | #include <linux/mm_types.h> |
9223b419 CL |
11 | #include <linux/bounds.h> |
12 | #endif /* !__GENERATING_BOUNDS_H */ | |
f886ed44 | 13 | |
1da177e4 LT |
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 | * | |
da6052f7 NP |
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. | |
1da177e4 | 23 | * |
da6052f7 NP |
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. | |
1da177e4 LT |
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 | * | |
da6052f7 NP |
37 | * PG_referenced, PG_reclaim are used for page reclaim for anonymous and |
38 | * file-backed pagecache (see mm/vmscan.c). | |
1da177e4 LT |
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... | |
da6052f7 NP |
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 | * | |
1da177e4 LT |
54 | */ |
55 | ||
56 | /* | |
57 | * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break | |
91fc8ab3 AW |
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 | | |
9223b419 CL |
65 | * N-1 ^ 0 |
66 | * (NR_PAGEFLAGS) | |
91fc8ab3 | 67 | * |
9223b419 CL |
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). | |
1da177e4 | 71 | */ |
e2683181 CL |
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*/ | |
e2683181 CL |
82 | PG_arch_1, |
83 | PG_reserved, | |
84 | PG_private, /* If pagecache, has fs-private data */ | |
266cf658 | 85 | PG_private_2, /* If pagecache, has fs aux data */ |
e2683181 | 86 | PG_writeback, /* Page is under writeback */ |
e20b8cca CL |
87 | #ifdef CONFIG_PAGEFLAGS_EXTENDED |
88 | PG_head, /* A head page */ | |
89 | PG_tail, /* A tail page */ | |
90 | #else | |
e2683181 | 91 | PG_compound, /* A compound page */ |
e20b8cca | 92 | #endif |
e2683181 CL |
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 */ | |
e2683181 | 96 | PG_buddy, /* Page is free, on buddy lists */ |
b2e18538 | 97 | PG_swapbacked, /* Page is backed by RAM/swap */ |
894bc310 | 98 | PG_unevictable, /* Page is "unevictable" */ |
33925b25 | 99 | #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT |
b291f000 | 100 | PG_mlocked, /* Page is vma mlocked */ |
894bc310 | 101 | #endif |
602c4d11 CL |
102 | #ifdef CONFIG_IA64_UNCACHED_ALLOCATOR |
103 | PG_uncached, /* Page has been mapped as uncached */ | |
f886ed44 | 104 | #endif |
0cad47cf AW |
105 | __NR_PAGEFLAGS, |
106 | ||
107 | /* Filesystems */ | |
108 | PG_checked = PG_owner_priv_1, | |
109 | ||
266cf658 DH |
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 | ||
0cad47cf AW |
116 | /* XEN */ |
117 | PG_pinned = PG_owner_priv_1, | |
118 | PG_savepinned = PG_dirty, | |
8a38082d | 119 | |
9023cb7e | 120 | /* SLOB */ |
9023cb7e AW |
121 | PG_slob_free = PG_private, |
122 | ||
8a38082d AW |
123 | /* SLUB */ |
124 | PG_slub_frozen = PG_active, | |
125 | PG_slub_debug = PG_error, | |
e2683181 | 126 | }; |
1da177e4 | 127 | |
9223b419 CL |
128 | #ifndef __GENERATING_BOUNDS_H |
129 | ||
f94a62e9 CL |
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 | ||
162 | #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ | |
163 | SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) | |
164 | ||
165 | #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ | |
166 | __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname) | |
167 | ||
ec7cade8 CL |
168 | #define PAGEFLAG_FALSE(uname) \ |
169 | static inline int Page##uname(struct page *page) \ | |
170 | { return 0; } | |
171 | ||
f94a62e9 CL |
172 | #define TESTSCFLAG(uname, lname) \ |
173 | TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname) | |
174 | ||
8a7a8544 LS |
175 | #define SETPAGEFLAG_NOOP(uname) \ |
176 | static inline void SetPage##uname(struct page *page) { } | |
177 | ||
178 | #define CLEARPAGEFLAG_NOOP(uname) \ | |
179 | static inline void ClearPage##uname(struct page *page) { } | |
180 | ||
181 | #define __CLEARPAGEFLAG_NOOP(uname) \ | |
182 | static inline void __ClearPage##uname(struct page *page) { } | |
183 | ||
184 | #define TESTCLEARFLAG_FALSE(uname) \ | |
185 | static inline int TestClearPage##uname(struct page *page) { return 0; } | |
186 | ||
6a1e7f77 CL |
187 | struct page; /* forward declaration */ |
188 | ||
03fb3d2a | 189 | TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked) |
6a1e7f77 CL |
190 | PAGEFLAG(Error, error) |
191 | PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced) | |
192 | PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty) | |
193 | PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru) | |
194 | PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active) | |
894bc310 | 195 | TESTCLEARFLAG(Active, active) |
6a1e7f77 | 196 | __PAGEFLAG(Slab, slab) |
0cad47cf AW |
197 | PAGEFLAG(Checked, checked) /* Used by some filesystems */ |
198 | PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */ | |
199 | PAGEFLAG(SavePinned, savepinned); /* Xen */ | |
6a1e7f77 | 200 | PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) |
b2e18538 | 201 | PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) |
6a1e7f77 | 202 | |
9023cb7e AW |
203 | __PAGEFLAG(SlobFree, slob_free) |
204 | ||
8a38082d AW |
205 | __PAGEFLAG(SlubFrozen, slub_frozen) |
206 | __PAGEFLAG(SlubDebug, slub_debug) | |
207 | ||
266cf658 DH |
208 | /* |
209 | * Private page markings that may be used by the filesystem that owns the page | |
210 | * for its own purposes. | |
211 | * - PG_private and PG_private_2 cause releasepage() and co to be invoked | |
212 | */ | |
213 | PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private) | |
214 | __CLEARPAGEFLAG(Private, private) | |
215 | PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2) | |
216 | PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1) | |
217 | ||
6a1e7f77 CL |
218 | /* |
219 | * Only test-and-set exist for PG_writeback. The unconditional operators are | |
220 | * risky: they bypass page accounting. | |
221 | */ | |
222 | TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback) | |
223 | __PAGEFLAG(Buddy, buddy) | |
224 | PAGEFLAG(MappedToDisk, mappedtodisk) | |
225 | ||
226 | /* PG_readahead is only used for file reads; PG_reclaim is only for writes */ | |
227 | PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim) | |
0a128b2b | 228 | PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */ |
6a1e7f77 CL |
229 | |
230 | #ifdef CONFIG_HIGHMEM | |
1da177e4 | 231 | /* |
6a1e7f77 CL |
232 | * Must use a macro here due to header dependency issues. page_zone() is not |
233 | * available at this point. | |
1da177e4 | 234 | */ |
0a128b2b | 235 | #define PageHighMem(__p) is_highmem(page_zone(__p)) |
6a1e7f77 | 236 | #else |
ec7cade8 | 237 | PAGEFLAG_FALSE(HighMem) |
6a1e7f77 CL |
238 | #endif |
239 | ||
240 | #ifdef CONFIG_SWAP | |
241 | PAGEFLAG(SwapCache, swapcache) | |
242 | #else | |
ec7cade8 | 243 | PAGEFLAG_FALSE(SwapCache) |
6d91add0 | 244 | SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache) |
6a1e7f77 CL |
245 | #endif |
246 | ||
894bc310 LS |
247 | PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable) |
248 | TESTCLEARFLAG(Unevictable, unevictable) | |
b291f000 | 249 | |
33925b25 | 250 | #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT |
b291f000 NP |
251 | #define MLOCK_PAGES 1 |
252 | PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked) | |
253 | TESTSCFLAG(Mlocked, mlocked) | |
894bc310 | 254 | #else |
b291f000 NP |
255 | #define MLOCK_PAGES 0 |
256 | PAGEFLAG_FALSE(Mlocked) | |
257 | SETPAGEFLAG_NOOP(Mlocked) TESTCLEARFLAG_FALSE(Mlocked) | |
894bc310 LS |
258 | #endif |
259 | ||
602c4d11 | 260 | #ifdef CONFIG_IA64_UNCACHED_ALLOCATOR |
6a1e7f77 | 261 | PAGEFLAG(Uncached, uncached) |
602c4d11 | 262 | #else |
ec7cade8 | 263 | PAGEFLAG_FALSE(Uncached) |
6a1e7f77 | 264 | #endif |
1da177e4 | 265 | |
0ed361de NP |
266 | static inline int PageUptodate(struct page *page) |
267 | { | |
268 | int ret = test_bit(PG_uptodate, &(page)->flags); | |
269 | ||
270 | /* | |
271 | * Must ensure that the data we read out of the page is loaded | |
272 | * _after_ we've loaded page->flags to check for PageUptodate. | |
273 | * We can skip the barrier if the page is not uptodate, because | |
274 | * we wouldn't be reading anything from it. | |
275 | * | |
276 | * See SetPageUptodate() for the other side of the story. | |
277 | */ | |
278 | if (ret) | |
279 | smp_rmb(); | |
280 | ||
281 | return ret; | |
282 | } | |
283 | ||
284 | static inline void __SetPageUptodate(struct page *page) | |
285 | { | |
286 | smp_wmb(); | |
287 | __set_bit(PG_uptodate, &(page)->flags); | |
0ed361de NP |
288 | } |
289 | ||
2dcea57a HC |
290 | static inline void SetPageUptodate(struct page *page) |
291 | { | |
0ed361de | 292 | #ifdef CONFIG_S390 |
2dcea57a | 293 | if (!test_and_set_bit(PG_uptodate, &page->flags)) |
6c210482 | 294 | page_clear_dirty(page); |
f6ac2354 | 295 | #else |
0ed361de NP |
296 | /* |
297 | * Memory barrier must be issued before setting the PG_uptodate bit, | |
298 | * so that all previous stores issued in order to bring the page | |
299 | * uptodate are actually visible before PageUptodate becomes true. | |
300 | * | |
301 | * s390 doesn't need an explicit smp_wmb here because the test and | |
302 | * set bit already provides full barriers. | |
303 | */ | |
304 | smp_wmb(); | |
305 | set_bit(PG_uptodate, &(page)->flags); | |
1da177e4 | 306 | #endif |
0ed361de NP |
307 | } |
308 | ||
6a1e7f77 | 309 | CLEARPAGEFLAG(Uptodate, uptodate) |
1da177e4 | 310 | |
6a1e7f77 | 311 | extern void cancel_dirty_page(struct page *page, unsigned int account_size); |
d77c2d7c | 312 | |
6a1e7f77 CL |
313 | int test_clear_page_writeback(struct page *page); |
314 | int test_set_page_writeback(struct page *page); | |
1da177e4 | 315 | |
6a1e7f77 CL |
316 | static inline void set_page_writeback(struct page *page) |
317 | { | |
318 | test_set_page_writeback(page); | |
319 | } | |
1da177e4 | 320 | |
e20b8cca CL |
321 | #ifdef CONFIG_PAGEFLAGS_EXTENDED |
322 | /* | |
323 | * System with lots of page flags available. This allows separate | |
324 | * flags for PageHead() and PageTail() checks of compound pages so that bit | |
325 | * tests can be used in performance sensitive paths. PageCompound is | |
326 | * generally not used in hot code paths. | |
327 | */ | |
328 | __PAGEFLAG(Head, head) | |
329 | __PAGEFLAG(Tail, tail) | |
330 | ||
331 | static inline int PageCompound(struct page *page) | |
332 | { | |
333 | return page->flags & ((1L << PG_head) | (1L << PG_tail)); | |
334 | ||
335 | } | |
336 | #else | |
337 | /* | |
338 | * Reduce page flag use as much as possible by overlapping | |
339 | * compound page flags with the flags used for page cache pages. Possible | |
340 | * because PageCompound is always set for compound pages and not for | |
341 | * pages on the LRU and/or pagecache. | |
342 | */ | |
6a1e7f77 CL |
343 | TESTPAGEFLAG(Compound, compound) |
344 | __PAGEFLAG(Head, compound) | |
1da177e4 | 345 | |
d85f3385 | 346 | /* |
6d777953 | 347 | * PG_reclaim is used in combination with PG_compound to mark the |
6a1e7f77 CL |
348 | * head and tail of a compound page. This saves one page flag |
349 | * but makes it impossible to use compound pages for the page cache. | |
350 | * The PG_reclaim bit would have to be used for reclaim or readahead | |
351 | * if compound pages enter the page cache. | |
6d777953 CL |
352 | * |
353 | * PG_compound & PG_reclaim => Tail page | |
354 | * PG_compound & ~PG_reclaim => Head page | |
d85f3385 | 355 | */ |
6d777953 CL |
356 | #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) |
357 | ||
6a1e7f77 CL |
358 | static inline int PageTail(struct page *page) |
359 | { | |
360 | return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask); | |
361 | } | |
6d777953 CL |
362 | |
363 | static inline void __SetPageTail(struct page *page) | |
364 | { | |
365 | page->flags |= PG_head_tail_mask; | |
366 | } | |
367 | ||
368 | static inline void __ClearPageTail(struct page *page) | |
369 | { | |
370 | page->flags &= ~PG_head_tail_mask; | |
371 | } | |
372 | ||
e20b8cca | 373 | #endif /* !PAGEFLAGS_EXTENDED */ |
dfa7e20c | 374 | |
33925b25 DH |
375 | #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT |
376 | #define __PG_MLOCKED (1 << PG_mlocked) | |
377 | #else | |
b291f000 | 378 | #define __PG_MLOCKED 0 |
894bc310 LS |
379 | #endif |
380 | ||
dfa7e20c RA |
381 | /* |
382 | * Flags checked when a page is freed. Pages being freed should not have | |
383 | * these flags set. It they are, there is a problem. | |
384 | */ | |
79f4b7bf | 385 | #define PAGE_FLAGS_CHECK_AT_FREE \ |
266cf658 DH |
386 | (1 << PG_lru | 1 << PG_locked | \ |
387 | 1 << PG_private | 1 << PG_private_2 | \ | |
388 | 1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \ | |
389 | 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ | |
68377659 | 390 | 1 << PG_unevictable | __PG_MLOCKED) |
dfa7e20c RA |
391 | |
392 | /* | |
393 | * Flags checked when a page is prepped for return by the page allocator. | |
79f4b7bf HD |
394 | * Pages being prepped should not have any flags set. It they are set, |
395 | * there has been a kernel bug or struct page corruption. | |
dfa7e20c | 396 | */ |
79f4b7bf | 397 | #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) |
dfa7e20c | 398 | |
9223b419 | 399 | #endif /* !__GENERATING_BOUNDS_H */ |
266cf658 DH |
400 | |
401 | /** | |
402 | * page_has_private - Determine if page has private stuff | |
403 | * @page: The page to be checked | |
404 | * | |
405 | * Determine if a page has private stuff, indicating that release routines | |
406 | * should be invoked upon it. | |
407 | */ | |
408 | #define page_has_private(page) \ | |
409 | ((page)->flags & ((1 << PG_private) | \ | |
410 | (1 << PG_private_2))) | |
411 | ||
1da177e4 | 412 | #endif /* PAGE_FLAGS_H */ |