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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Macros for manipulating and testing page->flags
3 */
4
5#ifndef PAGE_FLAGS_H
6#define PAGE_FLAGS_H
7
Andrew Mortonf886ed42006-06-23 02:03:06 -07008#include <linux/types.h>
Christoph Lameter6d777952007-05-06 14:49:40 -07009#include <linux/mm_types.h>
Andrew Mortonf886ed42006-06-23 02:03:06 -070010
Linus Torvalds1da177e2005-04-16 15:20:36 -070011/*
12 * Various page->flags bits:
13 *
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)...
16 *
Nick Pigginda6052f2006-09-25 23:31:35 -070017 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 *
Nick Pigginda6052f2006-09-25 23:31:35 -070021 * 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.
24 *
25 * PG_locked also pins a page in pagecache, and blocks truncation of the file
26 * while it is held.
27 *
28 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
29 * to become unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 *
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.
33 *
Nick Pigginda6052f2006-09-25 23:31:35 -070034 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
35 * file-backed pagecache (see mm/vmscan.c).
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 *
37 * PG_error is set to indicate that an I/O error occurred on this page.
38 *
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
41 * the page cache.
42 *
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
46 * address space...
Nick Pigginda6052f2006-09-25 23:31:35 -070047 *
48 * PG_buddy is set to indicate that the page is free and in the buddy system
49 * (see mm/page_alloc.c).
50 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 */
52
53/*
54 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
Andy Whitcroft91fc8ab2006-04-10 22:53:01 -070055 * locked- and dirty-page accounting.
56 *
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.
60 *
61 * | FIELD | ... | FLAGS |
62 * N-1 ^ 0
63 * (N-FLAGS_RESERVED)
64 *
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 */
70#define PG_locked 0 /* Page is locked. Don't touch. */
71#define PG_error 1
72#define PG_referenced 2
73#define PG_uptodate 3
74
75#define PG_dirty 4
76#define PG_lru 5
77#define PG_active 6
78#define PG_slab 7 /* slab debug (Suparna wants this) */
79
Nick Piggin5409bae2007-02-28 20:12:27 -080080#define PG_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/
Badari Pulavartycbe37d02005-06-21 17:14:52 -070081#define PG_arch_1 9
82#define PG_reserved 10
Nick Pigginda6052f2006-09-25 23:31:35 -070083#define PG_private 11 /* If pagecache, has fs-private data */
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Badari Pulavartycbe37d02005-06-21 17:14:52 -070085#define PG_writeback 12 /* Page is under writeback */
Badari Pulavartycbe37d02005-06-21 17:14:52 -070086#define PG_compound 14 /* Part of a compound page */
87#define PG_swapcache 15 /* Swap page: swp_entry_t in private */
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
Badari Pulavartycbe37d02005-06-21 17:14:52 -070089#define PG_mappedtodisk 16 /* Has blocks allocated on-disk */
90#define PG_reclaim 17 /* To be reclaimed asap */
Nick Piggin676165a2006-04-10 11:21:48 +100091#define PG_buddy 19 /* Page is free, on buddy lists */
92
Fengguang Wufe3cba12007-07-19 01:48:07 -070093/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
94#define PG_readahead PG_reclaim /* Reminder to do async read-ahead */
95
Nick Piggin5409bae2007-02-28 20:12:27 -080096/* PG_owner_priv_1 users should have descriptive aliases */
97#define PG_checked PG_owner_priv_1 /* Used by some filesystems */
Jeremy Fitzhardingec85b04c2007-07-17 18:37:05 -070098#define PG_pinned PG_owner_priv_1 /* Xen pinned pagetable */
Andrew Mortonf886ed42006-06-23 02:03:06 -070099
100#if (BITS_PER_LONG > 32)
101/*
102 * 64-bit-only flags build down from bit 31
103 *
104 * 32 bit -------------------------------| FIELDS | FLAGS |
105 * 64 bit | FIELDS | ?????? FLAGS |
106 * 63 32 0
107 */
108#define PG_uncached 31 /* Page has been mapped as uncached */
109#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110
111/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 * Manipulation of page state flags
113 */
114#define PageLocked(page) \
115 test_bit(PG_locked, &(page)->flags)
116#define SetPageLocked(page) \
117 set_bit(PG_locked, &(page)->flags)
118#define TestSetPageLocked(page) \
119 test_and_set_bit(PG_locked, &(page)->flags)
120#define ClearPageLocked(page) \
121 clear_bit(PG_locked, &(page)->flags)
122#define TestClearPageLocked(page) \
123 test_and_clear_bit(PG_locked, &(page)->flags)
124
125#define PageError(page) test_bit(PG_error, &(page)->flags)
126#define SetPageError(page) set_bit(PG_error, &(page)->flags)
127#define ClearPageError(page) clear_bit(PG_error, &(page)->flags)
128
129#define PageReferenced(page) test_bit(PG_referenced, &(page)->flags)
130#define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
131#define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
132#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
133
Nick Piggin0ed361d2008-02-04 22:29:34 -0800134static inline int PageUptodate(struct page *page)
135{
136 int ret = test_bit(PG_uptodate, &(page)->flags);
137
138 /*
139 * Must ensure that the data we read out of the page is loaded
140 * _after_ we've loaded page->flags to check for PageUptodate.
141 * We can skip the barrier if the page is not uptodate, because
142 * we wouldn't be reading anything from it.
143 *
144 * See SetPageUptodate() for the other side of the story.
145 */
146 if (ret)
147 smp_rmb();
148
149 return ret;
150}
151
152static inline void __SetPageUptodate(struct page *page)
153{
154 smp_wmb();
155 __set_bit(PG_uptodate, &(page)->flags);
Christoph Lameterf6ac2352006-06-30 01:55:32 -0700156#ifdef CONFIG_S390
Nick Piggin0ed361d2008-02-04 22:29:34 -0800157 page_clear_dirty(page);
158#endif
159}
160
Heiko Carstens2dcea572006-09-29 01:58:41 -0700161static inline void SetPageUptodate(struct page *page)
162{
Nick Piggin0ed361d2008-02-04 22:29:34 -0800163#ifdef CONFIG_S390
Heiko Carstens2dcea572006-09-29 01:58:41 -0700164 if (!test_and_set_bit(PG_uptodate, &page->flags))
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200165 page_clear_dirty(page);
Christoph Lameterf6ac2352006-06-30 01:55:32 -0700166#else
Nick Piggin0ed361d2008-02-04 22:29:34 -0800167 /*
168 * Memory barrier must be issued before setting the PG_uptodate bit,
169 * so that all previous stores issued in order to bring the page
170 * uptodate are actually visible before PageUptodate becomes true.
171 *
172 * s390 doesn't need an explicit smp_wmb here because the test and
173 * set bit already provides full barriers.
174 */
175 smp_wmb();
176 set_bit(PG_uptodate, &(page)->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177#endif
Nick Piggin0ed361d2008-02-04 22:29:34 -0800178}
179
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
181
182#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
183#define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)
184#define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags)
185#define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags)
Nick Piggin242e5462005-09-03 15:54:50 -0700186#define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
188
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189#define PageLRU(page) test_bit(PG_lru, &(page)->flags)
Nick Piggin8d438f92006-03-22 00:07:59 -0800190#define SetPageLRU(page) set_bit(PG_lru, &(page)->flags)
191#define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags)
Nick Piggin67453912006-03-22 00:08:00 -0800192#define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
194#define PageActive(page) test_bit(PG_active, &(page)->flags)
195#define SetPageActive(page) set_bit(PG_active, &(page)->flags)
196#define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
Nick Piggin67453912006-03-22 00:08:00 -0800197#define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
199#define PageSlab(page) test_bit(PG_slab, &(page)->flags)
Nick Pigginf205b2f2006-03-22 00:08:02 -0800200#define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags)
201#define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
203#ifdef CONFIG_HIGHMEM
Badari Pulavartycbe37d02005-06-21 17:14:52 -0700204#define PageHighMem(page) is_highmem(page_zone(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205#else
206#define PageHighMem(page) 0 /* needed to optimize away at compile time */
207#endif
208
209#define PageChecked(page) test_bit(PG_checked, &(page)->flags)
210#define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
211#define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
212
Jeremy Fitzhardingec85b04c2007-07-17 18:37:05 -0700213#define PagePinned(page) test_bit(PG_pinned, &(page)->flags)
214#define SetPagePinned(page) set_bit(PG_pinned, &(page)->flags)
215#define ClearPagePinned(page) clear_bit(PG_pinned, &(page)->flags)
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217#define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
218#define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
219#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
220#define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags)
221
222#define SetPagePrivate(page) set_bit(PG_private, &(page)->flags)
223#define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags)
224#define PagePrivate(page) test_bit(PG_private, &(page)->flags)
225#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
226#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
227
Andrew Mortond688abf2007-07-19 01:49:17 -0700228/*
229 * Only test-and-set exist for PG_writeback. The unconditional operators are
230 * risky: they bypass page accounting.
231 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
Andrew Mortond688abf2007-07-19 01:49:17 -0700233#define TestSetPageWriteback(page) test_and_set_bit(PG_writeback, \
234 &(page)->flags)
235#define TestClearPageWriteback(page) test_and_clear_bit(PG_writeback, \
236 &(page)->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237
Nick Piggin676165a2006-04-10 11:21:48 +1000238#define PageBuddy(page) test_bit(PG_buddy, &(page)->flags)
239#define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags)
240#define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags)
241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242#define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags)
243#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
244#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
245
Fengguang Wud77c2d72007-07-19 01:47:55 -0700246#define PageReadahead(page) test_bit(PG_readahead, &(page)->flags)
247#define SetPageReadahead(page) set_bit(PG_readahead, &(page)->flags)
248#define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
249
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250#define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
251#define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
252#define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
253#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
254
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255#define PageCompound(page) test_bit(PG_compound, &(page)->flags)
Nick Piggin5e9dace2006-03-22 00:08:01 -0800256#define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
257#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
Christoph Lameterd85f3382007-05-06 14:49:39 -0700259/*
Christoph Lameter6d777952007-05-06 14:49:40 -0700260 * PG_reclaim is used in combination with PG_compound to mark the
261 * head and tail of a compound page
262 *
263 * PG_compound & PG_reclaim => Tail page
264 * PG_compound & ~PG_reclaim => Head page
Christoph Lameterd85f3382007-05-06 14:49:39 -0700265 */
Christoph Lameter6d777952007-05-06 14:49:40 -0700266
267#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
268
David Howellsa62f7352008-02-21 16:12:45 +0000269#define PageTail(page) (((page)->flags & PG_head_tail_mask) \
Christoph Lameter6d777952007-05-06 14:49:40 -0700270 == PG_head_tail_mask)
271
272static inline void __SetPageTail(struct page *page)
273{
274 page->flags |= PG_head_tail_mask;
275}
276
277static inline void __ClearPageTail(struct page *page)
278{
279 page->flags &= ~PG_head_tail_mask;
280}
281
David Howellsa62f7352008-02-21 16:12:45 +0000282#define PageHead(page) (((page)->flags & PG_head_tail_mask) \
Christoph Lameter6d777952007-05-06 14:49:40 -0700283 == (1L << PG_compound))
284#define __SetPageHead(page) __SetPageCompound(page)
285#define __ClearPageHead(page) __ClearPageCompound(page)
Christoph Lameterd85f3382007-05-06 14:49:39 -0700286
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287#ifdef CONFIG_SWAP
288#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
289#define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
290#define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
291#else
292#define PageSwapCache(page) 0
293#endif
294
295#define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
296#define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
297#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
298
299struct page; /* forward declaration */
300
Linus Torvaldsfba25912006-12-20 13:46:42 -0800301extern void cancel_dirty_page(struct page *page, unsigned int account_size);
302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303int test_clear_page_writeback(struct page *page);
304int test_set_page_writeback(struct page *page);
305
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306static inline void set_page_writeback(struct page *page)
307{
308 test_set_page_writeback(page);
309}
310
311#endif /* PAGE_FLAGS_H */