]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blame - include/linux/pagemap.h
Merge tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg...
[mirror_ubuntu-bionic-kernel.git] / include / linux / pagemap.h
CommitLineData
1da177e4
LT
1#ifndef _LINUX_PAGEMAP_H
2#define _LINUX_PAGEMAP_H
3
4/*
5 * Copyright 1995 Linus Torvalds
6 */
7#include <linux/mm.h>
8#include <linux/fs.h>
9#include <linux/list.h>
10#include <linux/highmem.h>
11#include <linux/compiler.h>
12#include <asm/uaccess.h>
13#include <linux/gfp.h>
3e9f45bd 14#include <linux/bitops.h>
e286781d 15#include <linux/hardirq.h> /* for in_interrupt() */
8edf344c 16#include <linux/hugetlb_inline.h>
1da177e4
LT
17
18/*
19 * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
20 * allocation mode flags.
21 */
9a896c9a
LS
22enum mapping_flags {
23 AS_EIO = __GFP_BITS_SHIFT + 0, /* IO error on async write */
24 AS_ENOSPC = __GFP_BITS_SHIFT + 1, /* ENOSPC on async write */
25 AS_MM_ALL_LOCKS = __GFP_BITS_SHIFT + 2, /* under mm_take_all_locks() */
9a896c9a 26 AS_UNEVICTABLE = __GFP_BITS_SHIFT + 3, /* e.g., ramdisk, SHM_LOCK */
18468d93 27 AS_BALLOON_MAP = __GFP_BITS_SHIFT + 4, /* balloon page special map */
9a896c9a 28};
1da177e4 29
3e9f45bd
GC
30static inline void mapping_set_error(struct address_space *mapping, int error)
31{
2185e69f 32 if (unlikely(error)) {
3e9f45bd
GC
33 if (error == -ENOSPC)
34 set_bit(AS_ENOSPC, &mapping->flags);
35 else
36 set_bit(AS_EIO, &mapping->flags);
37 }
38}
39
ba9ddf49
LS
40static inline void mapping_set_unevictable(struct address_space *mapping)
41{
42 set_bit(AS_UNEVICTABLE, &mapping->flags);
43}
44
89e004ea
LS
45static inline void mapping_clear_unevictable(struct address_space *mapping)
46{
47 clear_bit(AS_UNEVICTABLE, &mapping->flags);
48}
49
ba9ddf49
LS
50static inline int mapping_unevictable(struct address_space *mapping)
51{
088e5465 52 if (mapping)
89e004ea
LS
53 return test_bit(AS_UNEVICTABLE, &mapping->flags);
54 return !!mapping;
ba9ddf49 55}
ba9ddf49 56
18468d93
RA
57static inline void mapping_set_balloon(struct address_space *mapping)
58{
59 set_bit(AS_BALLOON_MAP, &mapping->flags);
60}
61
62static inline void mapping_clear_balloon(struct address_space *mapping)
63{
64 clear_bit(AS_BALLOON_MAP, &mapping->flags);
65}
66
67static inline int mapping_balloon(struct address_space *mapping)
68{
69 return mapping && test_bit(AS_BALLOON_MAP, &mapping->flags);
70}
71
dd0fc66f 72static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
1da177e4 73{
260b2367 74 return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
1da177e4
LT
75}
76
77/*
78 * This is non-atomic. Only to be used before the mapping is activated.
79 * Probably needs a barrier...
80 */
260b2367 81static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
1da177e4 82{
260b2367
AV
83 m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
84 (__force unsigned long)mask;
1da177e4
LT
85}
86
87/*
88 * The page cache can done in larger chunks than
89 * one page, because it allows for more efficient
90 * throughput (it can then be mapped into user
91 * space in smaller chunks for same flexibility).
92 *
93 * Or rather, it _will_ be done in larger chunks.
94 */
95#define PAGE_CACHE_SHIFT PAGE_SHIFT
96#define PAGE_CACHE_SIZE PAGE_SIZE
97#define PAGE_CACHE_MASK PAGE_MASK
98#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
99
100#define page_cache_get(page) get_page(page)
101#define page_cache_release(page) put_page(page)
102void release_pages(struct page **pages, int nr, int cold);
103
e286781d
NP
104/*
105 * speculatively take a reference to a page.
106 * If the page is free (_count == 0), then _count is untouched, and 0
107 * is returned. Otherwise, _count is incremented by 1 and 1 is returned.
108 *
109 * This function must be called inside the same rcu_read_lock() section as has
110 * been used to lookup the page in the pagecache radix-tree (or page table):
111 * this allows allocators to use a synchronize_rcu() to stabilize _count.
112 *
113 * Unless an RCU grace period has passed, the count of all pages coming out
114 * of the allocator must be considered unstable. page_count may return higher
115 * than expected, and put_page must be able to do the right thing when the
116 * page has been finished with, no matter what it is subsequently allocated
117 * for (because put_page is what is used here to drop an invalid speculative
118 * reference).
119 *
120 * This is the interesting part of the lockless pagecache (and lockless
121 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
122 * has the following pattern:
123 * 1. find page in radix tree
124 * 2. conditionally increment refcount
125 * 3. check the page is still in pagecache (if no, goto 1)
126 *
127 * Remove-side that cares about stability of _count (eg. reclaim) has the
128 * following (with tree_lock held for write):
129 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
130 * B. remove page from pagecache
131 * C. free the page
132 *
133 * There are 2 critical interleavings that matter:
134 * - 2 runs before A: in this case, A sees elevated refcount and bails out
135 * - A runs before 2: in this case, 2 sees zero refcount and retries;
136 * subsequently, B will complete and 1 will find no page, causing the
137 * lookup to return NULL.
138 *
139 * It is possible that between 1 and 2, the page is removed then the exact same
140 * page is inserted into the same position in pagecache. That's OK: the
141 * old find_get_page using tree_lock could equally have run before or after
142 * such a re-insertion, depending on order that locks are granted.
143 *
144 * Lookups racing against pagecache insertion isn't a big problem: either 1
145 * will find the page or it will not. Likewise, the old find_get_page could run
146 * either before the insertion or afterwards, depending on timing.
147 */
148static inline int page_cache_get_speculative(struct page *page)
149{
150 VM_BUG_ON(in_interrupt());
151
8375ad98 152#ifdef CONFIG_TINY_RCU
bdd4e85d 153# ifdef CONFIG_PREEMPT_COUNT
e286781d
NP
154 VM_BUG_ON(!in_atomic());
155# endif
156 /*
157 * Preempt must be disabled here - we rely on rcu_read_lock doing
158 * this for us.
159 *
160 * Pagecache won't be truncated from interrupt context, so if we have
161 * found a page in the radix tree here, we have pinned its refcount by
162 * disabling preempt, and hence no need for the "speculative get" that
163 * SMP requires.
164 */
165 VM_BUG_ON(page_count(page) == 0);
166 atomic_inc(&page->_count);
167
168#else
169 if (unlikely(!get_page_unless_zero(page))) {
170 /*
171 * Either the page has been freed, or will be freed.
172 * In either case, retry here and the caller should
173 * do the right thing (see comments above).
174 */
175 return 0;
176 }
177#endif
178 VM_BUG_ON(PageTail(page));
179
180 return 1;
181}
182
ce0ad7f0
NP
183/*
184 * Same as above, but add instead of inc (could just be merged)
185 */
186static inline int page_cache_add_speculative(struct page *page, int count)
187{
188 VM_BUG_ON(in_interrupt());
189
b560d8ad 190#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
bdd4e85d 191# ifdef CONFIG_PREEMPT_COUNT
ce0ad7f0
NP
192 VM_BUG_ON(!in_atomic());
193# endif
194 VM_BUG_ON(page_count(page) == 0);
195 atomic_add(count, &page->_count);
196
197#else
198 if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
199 return 0;
200#endif
201 VM_BUG_ON(PageCompound(page) && page != compound_head(page));
202
203 return 1;
204}
205
e286781d
NP
206static inline int page_freeze_refs(struct page *page, int count)
207{
208 return likely(atomic_cmpxchg(&page->_count, count, 0) == count);
209}
210
211static inline void page_unfreeze_refs(struct page *page, int count)
212{
213 VM_BUG_ON(page_count(page) != 0);
214 VM_BUG_ON(count == 0);
215
216 atomic_set(&page->_count, count);
217}
218
44110fe3 219#ifdef CONFIG_NUMA
2ae88149 220extern struct page *__page_cache_alloc(gfp_t gfp);
44110fe3 221#else
2ae88149
NP
222static inline struct page *__page_cache_alloc(gfp_t gfp)
223{
224 return alloc_pages(gfp, 0);
225}
226#endif
227
1da177e4
LT
228static inline struct page *page_cache_alloc(struct address_space *x)
229{
2ae88149 230 return __page_cache_alloc(mapping_gfp_mask(x));
1da177e4
LT
231}
232
233static inline struct page *page_cache_alloc_cold(struct address_space *x)
234{
2ae88149 235 return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
1da177e4
LT
236}
237
7b1de586
WF
238static inline struct page *page_cache_alloc_readahead(struct address_space *x)
239{
240 return __page_cache_alloc(mapping_gfp_mask(x) |
241 __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN);
242}
243
1da177e4
LT
244typedef int filler_t(void *, struct page *);
245
246extern struct page * find_get_page(struct address_space *mapping,
57f6b96c 247 pgoff_t index);
1da177e4 248extern struct page * find_lock_page(struct address_space *mapping,
57f6b96c 249 pgoff_t index);
1da177e4 250extern struct page * find_or_create_page(struct address_space *mapping,
57f6b96c 251 pgoff_t index, gfp_t gfp_mask);
1da177e4
LT
252unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
253 unsigned int nr_pages, struct page **pages);
ebf43500
JA
254unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
255 unsigned int nr_pages, struct page **pages);
1da177e4
LT
256unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
257 int tag, unsigned int nr_pages, struct page **pages);
258
54566b2c
NP
259struct page *grab_cache_page_write_begin(struct address_space *mapping,
260 pgoff_t index, unsigned flags);
afddba49 261
1da177e4
LT
262/*
263 * Returns locked page at given index in given cache, creating it if needed.
264 */
57f6b96c
FW
265static inline struct page *grab_cache_page(struct address_space *mapping,
266 pgoff_t index)
1da177e4
LT
267{
268 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
269}
270
271extern struct page * grab_cache_page_nowait(struct address_space *mapping,
57f6b96c 272 pgoff_t index);
6fe6900e 273extern struct page * read_cache_page_async(struct address_space *mapping,
5e5358e7 274 pgoff_t index, filler_t *filler, void *data);
1da177e4 275extern struct page * read_cache_page(struct address_space *mapping,
5e5358e7 276 pgoff_t index, filler_t *filler, void *data);
0531b2aa
LT
277extern struct page * read_cache_page_gfp(struct address_space *mapping,
278 pgoff_t index, gfp_t gfp_mask);
1da177e4
LT
279extern int read_cache_pages(struct address_space *mapping,
280 struct list_head *pages, filler_t *filler, void *data);
281
6fe6900e 282static inline struct page *read_mapping_page_async(
5e5358e7
HD
283 struct address_space *mapping,
284 pgoff_t index, void *data)
6fe6900e
NP
285{
286 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
287 return read_cache_page_async(mapping, index, filler, data);
288}
289
090d2b18 290static inline struct page *read_mapping_page(struct address_space *mapping,
5e5358e7 291 pgoff_t index, void *data)
090d2b18
PE
292{
293 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
294 return read_cache_page(mapping, index, filler, data);
295}
296
1da177e4
LT
297/*
298 * Return byte-offset into filesystem object for page.
299 */
300static inline loff_t page_offset(struct page *page)
301{
302 return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
303}
304
f981c595
MG
305static inline loff_t page_file_offset(struct page *page)
306{
307 return ((loff_t)page_file_index(page)) << PAGE_CACHE_SHIFT;
308}
309
0fe6e20b
NH
310extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
311 unsigned long address);
312
1da177e4
LT
313static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
314 unsigned long address)
315{
0fe6e20b
NH
316 pgoff_t pgoff;
317 if (unlikely(is_vm_hugetlb_page(vma)))
318 return linear_hugepage_index(vma, address);
319 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
1da177e4
LT
320 pgoff += vma->vm_pgoff;
321 return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
322}
323
b3c97528
HH
324extern void __lock_page(struct page *page);
325extern int __lock_page_killable(struct page *page);
d065bd81
ML
326extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
327 unsigned int flags);
b3c97528 328extern void unlock_page(struct page *page);
1da177e4 329
f45840b5 330static inline void __set_page_locked(struct page *page)
529ae9aa 331{
f45840b5 332 __set_bit(PG_locked, &page->flags);
529ae9aa
NP
333}
334
f45840b5 335static inline void __clear_page_locked(struct page *page)
529ae9aa 336{
f45840b5 337 __clear_bit(PG_locked, &page->flags);
529ae9aa
NP
338}
339
340static inline int trylock_page(struct page *page)
341{
8413ac9d 342 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
529ae9aa
NP
343}
344
db37648c
NP
345/*
346 * lock_page may only be called if we have the page's inode pinned.
347 */
1da177e4
LT
348static inline void lock_page(struct page *page)
349{
350 might_sleep();
529ae9aa 351 if (!trylock_page(page))
1da177e4
LT
352 __lock_page(page);
353}
db37648c 354
2687a356
MW
355/*
356 * lock_page_killable is like lock_page but can be interrupted by fatal
357 * signals. It returns 0 if it locked the page and -EINTR if it was
358 * killed while waiting.
359 */
360static inline int lock_page_killable(struct page *page)
361{
362 might_sleep();
529ae9aa 363 if (!trylock_page(page))
2687a356
MW
364 return __lock_page_killable(page);
365 return 0;
366}
367
d065bd81
ML
368/*
369 * lock_page_or_retry - Lock the page, unless this would block and the
370 * caller indicated that it can handle a retry.
371 */
372static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
373 unsigned int flags)
374{
375 might_sleep();
376 return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
377}
378
1da177e4
LT
379/*
380 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
381 * Never use this directly!
382 */
b3c97528 383extern void wait_on_page_bit(struct page *page, int bit_nr);
1da177e4 384
f62e00cc
KM
385extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
386
387static inline int wait_on_page_locked_killable(struct page *page)
388{
389 if (PageLocked(page))
390 return wait_on_page_bit_killable(page, PG_locked);
391 return 0;
392}
393
1da177e4
LT
394/*
395 * Wait for a page to be unlocked.
396 *
397 * This must be called with the caller "holding" the page,
398 * ie with increased "page->count" so that the page won't
399 * go away during the wait..
400 */
401static inline void wait_on_page_locked(struct page *page)
402{
403 if (PageLocked(page))
404 wait_on_page_bit(page, PG_locked);
405}
406
407/*
408 * Wait for a page to complete writeback
409 */
410static inline void wait_on_page_writeback(struct page *page)
411{
412 if (PageWriteback(page))
413 wait_on_page_bit(page, PG_writeback);
414}
415
416extern void end_page_writeback(struct page *page);
1d1d1a76 417void wait_for_stable_page(struct page *page);
1da177e4 418
385e1ca5
DH
419/*
420 * Add an arbitrary waiter to a page's wait queue
421 */
422extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter);
423
1da177e4
LT
424/*
425 * Fault a userspace page into pagetables. Return non-zero on a fault.
426 *
427 * This assumes that two userspace pages are always sufficient. That's
428 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
429 */
430static inline int fault_in_pages_writeable(char __user *uaddr, int size)
431{
432 int ret;
433
08291429
NP
434 if (unlikely(size == 0))
435 return 0;
436
1da177e4
LT
437 /*
438 * Writing zeroes into userspace here is OK, because we know that if
439 * the zero gets there, we'll be overwriting it.
440 */
441 ret = __put_user(0, uaddr);
442 if (ret == 0) {
443 char __user *end = uaddr + size - 1;
444
445 /*
446 * If the page was already mapped, this will get a cache miss
447 * for sure, so try to avoid doing it.
448 */
449 if (((unsigned long)uaddr & PAGE_MASK) !=
450 ((unsigned long)end & PAGE_MASK))
f56f821f 451 ret = __put_user(0, end);
1da177e4
LT
452 }
453 return ret;
454}
455
08291429 456static inline int fault_in_pages_readable(const char __user *uaddr, int size)
1da177e4
LT
457{
458 volatile char c;
459 int ret;
460
08291429
NP
461 if (unlikely(size == 0))
462 return 0;
463
1da177e4
LT
464 ret = __get_user(c, uaddr);
465 if (ret == 0) {
466 const char __user *end = uaddr + size - 1;
467
468 if (((unsigned long)uaddr & PAGE_MASK) !=
627295e4 469 ((unsigned long)end & PAGE_MASK)) {
f56f821f 470 ret = __get_user(c, end);
627295e4
AK
471 (void)c;
472 }
1da177e4 473 }
08291429 474 return ret;
1da177e4
LT
475}
476
f56f821f
DV
477/*
478 * Multipage variants of the above prefault helpers, useful if more than
479 * PAGE_SIZE of data needs to be prefaulted. These are separate from the above
480 * functions (which only handle up to PAGE_SIZE) to avoid clobbering the
481 * filemap.c hotpaths.
482 */
483static inline int fault_in_multipages_writeable(char __user *uaddr, int size)
484{
af2e8409 485 int ret = 0;
9923777d 486 char __user *end = uaddr + size - 1;
f56f821f
DV
487
488 if (unlikely(size == 0))
af2e8409 489 return ret;
f56f821f
DV
490
491 /*
492 * Writing zeroes into userspace here is OK, because we know that if
493 * the zero gets there, we'll be overwriting it.
494 */
495 while (uaddr <= end) {
496 ret = __put_user(0, uaddr);
497 if (ret != 0)
498 return ret;
499 uaddr += PAGE_SIZE;
500 }
501
502 /* Check whether the range spilled into the next page. */
503 if (((unsigned long)uaddr & PAGE_MASK) ==
504 ((unsigned long)end & PAGE_MASK))
505 ret = __put_user(0, end);
506
507 return ret;
508}
509
510static inline int fault_in_multipages_readable(const char __user *uaddr,
511 int size)
512{
513 volatile char c;
af2e8409 514 int ret = 0;
f56f821f
DV
515 const char __user *end = uaddr + size - 1;
516
517 if (unlikely(size == 0))
af2e8409 518 return ret;
f56f821f
DV
519
520 while (uaddr <= end) {
521 ret = __get_user(c, uaddr);
522 if (ret != 0)
523 return ret;
524 uaddr += PAGE_SIZE;
525 }
526
527 /* Check whether the range spilled into the next page. */
528 if (((unsigned long)uaddr & PAGE_MASK) ==
529 ((unsigned long)end & PAGE_MASK)) {
530 ret = __get_user(c, end);
531 (void)c;
532 }
533
534 return ret;
535}
536
529ae9aa
NP
537int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
538 pgoff_t index, gfp_t gfp_mask);
539int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
540 pgoff_t index, gfp_t gfp_mask);
97cecb5a 541extern void delete_from_page_cache(struct page *page);
e64a782f 542extern void __delete_from_page_cache(struct page *page);
ef6a3c63 543int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
529ae9aa
NP
544
545/*
546 * Like add_to_page_cache_locked, but used to add newly allocated pages:
f45840b5 547 * the page is new, so we can just run __set_page_locked() against it.
529ae9aa
NP
548 */
549static inline int add_to_page_cache(struct page *page,
550 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
551{
552 int error;
553
f45840b5 554 __set_page_locked(page);
529ae9aa
NP
555 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
556 if (unlikely(error))
f45840b5 557 __clear_page_locked(page);
529ae9aa
NP
558 return error;
559}
560
1da177e4 561#endif /* _LINUX_PAGEMAP_H */