1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_PAGEMAP_H 3 #define _LINUX_PAGEMAP_H 4 5 /* 6 * Copyright 1995 Linus Torvalds 7 */ 8 #include <linux/mm.h> 9 #include <linux/fs.h> 10 #include <linux/list.h> 11 #include <linux/highmem.h> 12 #include <linux/compiler.h> 13 #include <linux/uaccess.h> 14 #include <linux/gfp.h> 15 #include <linux/bitops.h> 16 #include <linux/hardirq.h> /* for in_interrupt() */ 17 #include <linux/hugetlb_inline.h> 18 19 struct pagevec; 20 21 /* 22 * Bits in mapping->flags. 23 */ 24 enum mapping_flags { 25 AS_EIO = 0, /* IO error on async write */ 26 AS_ENOSPC = 1, /* ENOSPC on async write */ 27 AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */ 28 AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */ 29 AS_EXITING = 4, /* final truncate in progress */ 30 /* writeback related tags are not used */ 31 AS_NO_WRITEBACK_TAGS = 5, 32 }; 33 34 /** 35 * mapping_set_error - record a writeback error in the address_space 36 * @mapping - the mapping in which an error should be set 37 * @error - the error to set in the mapping 38 * 39 * When writeback fails in some way, we must record that error so that 40 * userspace can be informed when fsync and the like are called. We endeavor 41 * to report errors on any file that was open at the time of the error. Some 42 * internal callers also need to know when writeback errors have occurred. 43 * 44 * When a writeback error occurs, most filesystems will want to call 45 * mapping_set_error to record the error in the mapping so that it can be 46 * reported when the application calls fsync(2). 47 */ 48 static inline void mapping_set_error(struct address_space *mapping, int error) 49 { 50 if (likely(!error)) 51 return; 52 53 /* Record in wb_err for checkers using errseq_t based tracking */ 54 filemap_set_wb_err(mapping, error); 55 56 /* Record it in flags for now, for legacy callers */ 57 if (error == -ENOSPC) 58 set_bit(AS_ENOSPC, &mapping->flags); 59 else 60 set_bit(AS_EIO, &mapping->flags); 61 } 62 63 static inline void mapping_set_unevictable(struct address_space *mapping) 64 { 65 set_bit(AS_UNEVICTABLE, &mapping->flags); 66 } 67 68 static inline void mapping_clear_unevictable(struct address_space *mapping) 69 { 70 clear_bit(AS_UNEVICTABLE, &mapping->flags); 71 } 72 73 static inline int mapping_unevictable(struct address_space *mapping) 74 { 75 if (mapping) 76 return test_bit(AS_UNEVICTABLE, &mapping->flags); 77 return !!mapping; 78 } 79 80 static inline void mapping_set_exiting(struct address_space *mapping) 81 { 82 set_bit(AS_EXITING, &mapping->flags); 83 } 84 85 static inline int mapping_exiting(struct address_space *mapping) 86 { 87 return test_bit(AS_EXITING, &mapping->flags); 88 } 89 90 static inline void mapping_set_no_writeback_tags(struct address_space *mapping) 91 { 92 set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); 93 } 94 95 static inline int mapping_use_writeback_tags(struct address_space *mapping) 96 { 97 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); 98 } 99 100 static inline gfp_t mapping_gfp_mask(struct address_space * mapping) 101 { 102 return mapping->gfp_mask; 103 } 104 105 /* Restricts the given gfp_mask to what the mapping allows. */ 106 static inline gfp_t mapping_gfp_constraint(struct address_space *mapping, 107 gfp_t gfp_mask) 108 { 109 return mapping_gfp_mask(mapping) & gfp_mask; 110 } 111 112 /* 113 * This is non-atomic. Only to be used before the mapping is activated. 114 * Probably needs a barrier... 115 */ 116 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) 117 { 118 m->gfp_mask = mask; 119 } 120 121 void release_pages(struct page **pages, int nr); 122 123 /* 124 * speculatively take a reference to a page. 125 * If the page is free (_refcount == 0), then _refcount is untouched, and 0 126 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned. 127 * 128 * This function must be called inside the same rcu_read_lock() section as has 129 * been used to lookup the page in the pagecache radix-tree (or page table): 130 * this allows allocators to use a synchronize_rcu() to stabilize _refcount. 131 * 132 * Unless an RCU grace period has passed, the count of all pages coming out 133 * of the allocator must be considered unstable. page_count may return higher 134 * than expected, and put_page must be able to do the right thing when the 135 * page has been finished with, no matter what it is subsequently allocated 136 * for (because put_page is what is used here to drop an invalid speculative 137 * reference). 138 * 139 * This is the interesting part of the lockless pagecache (and lockless 140 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) 141 * has the following pattern: 142 * 1. find page in radix tree 143 * 2. conditionally increment refcount 144 * 3. check the page is still in pagecache (if no, goto 1) 145 * 146 * Remove-side that cares about stability of _refcount (eg. reclaim) has the 147 * following (with the i_pages lock held): 148 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) 149 * B. remove page from pagecache 150 * C. free the page 151 * 152 * There are 2 critical interleavings that matter: 153 * - 2 runs before A: in this case, A sees elevated refcount and bails out 154 * - A runs before 2: in this case, 2 sees zero refcount and retries; 155 * subsequently, B will complete and 1 will find no page, causing the 156 * lookup to return NULL. 157 * 158 * It is possible that between 1 and 2, the page is removed then the exact same 159 * page is inserted into the same position in pagecache. That's OK: the 160 * old find_get_page using a lock could equally have run before or after 161 * such a re-insertion, depending on order that locks are granted. 162 * 163 * Lookups racing against pagecache insertion isn't a big problem: either 1 164 * will find the page or it will not. Likewise, the old find_get_page could run 165 * either before the insertion or afterwards, depending on timing. 166 */ 167 static inline int __page_cache_add_speculative(struct page *page, int count) 168 { 169 #ifdef CONFIG_TINY_RCU 170 # ifdef CONFIG_PREEMPT_COUNT 171 VM_BUG_ON(!in_atomic() && !irqs_disabled()); 172 # endif 173 /* 174 * Preempt must be disabled here - we rely on rcu_read_lock doing 175 * this for us. 176 * 177 * Pagecache won't be truncated from interrupt context, so if we have 178 * found a page in the radix tree here, we have pinned its refcount by 179 * disabling preempt, and hence no need for the "speculative get" that 180 * SMP requires. 181 */ 182 VM_BUG_ON_PAGE(page_count(page) == 0, page); 183 page_ref_add(page, count); 184 185 #else 186 if (unlikely(!page_ref_add_unless(page, count, 0))) { 187 /* 188 * Either the page has been freed, or will be freed. 189 * In either case, retry here and the caller should 190 * do the right thing (see comments above). 191 */ 192 return 0; 193 } 194 #endif 195 VM_BUG_ON_PAGE(PageTail(page), page); 196 197 return 1; 198 } 199 200 static inline int page_cache_get_speculative(struct page *page) 201 { 202 return __page_cache_add_speculative(page, 1); 203 } 204 205 static inline int page_cache_add_speculative(struct page *page, int count) 206 { 207 return __page_cache_add_speculative(page, count); 208 } 209 210 #ifdef CONFIG_NUMA 211 extern struct page *__page_cache_alloc(gfp_t gfp); 212 #else 213 static inline struct page *__page_cache_alloc(gfp_t gfp) 214 { 215 return alloc_pages(gfp, 0); 216 } 217 #endif 218 219 static inline struct page *page_cache_alloc(struct address_space *x) 220 { 221 return __page_cache_alloc(mapping_gfp_mask(x)); 222 } 223 224 static inline gfp_t readahead_gfp_mask(struct address_space *x) 225 { 226 return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN; 227 } 228 229 typedef int filler_t(void *, struct page *); 230 231 pgoff_t page_cache_next_miss(struct address_space *mapping, 232 pgoff_t index, unsigned long max_scan); 233 pgoff_t page_cache_prev_miss(struct address_space *mapping, 234 pgoff_t index, unsigned long max_scan); 235 236 #define FGP_ACCESSED 0x00000001 237 #define FGP_LOCK 0x00000002 238 #define FGP_CREAT 0x00000004 239 #define FGP_WRITE 0x00000008 240 #define FGP_NOFS 0x00000010 241 #define FGP_NOWAIT 0x00000020 242 #define FGP_FOR_MMAP 0x00000040 243 244 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, 245 int fgp_flags, gfp_t cache_gfp_mask); 246 247 /** 248 * find_get_page - find and get a page reference 249 * @mapping: the address_space to search 250 * @offset: the page index 251 * 252 * Looks up the page cache slot at @mapping & @offset. If there is a 253 * page cache page, it is returned with an increased refcount. 254 * 255 * Otherwise, %NULL is returned. 256 */ 257 static inline struct page *find_get_page(struct address_space *mapping, 258 pgoff_t offset) 259 { 260 return pagecache_get_page(mapping, offset, 0, 0); 261 } 262 263 static inline struct page *find_get_page_flags(struct address_space *mapping, 264 pgoff_t offset, int fgp_flags) 265 { 266 return pagecache_get_page(mapping, offset, fgp_flags, 0); 267 } 268 269 /** 270 * find_lock_page - locate, pin and lock a pagecache page 271 * @mapping: the address_space to search 272 * @offset: the page index 273 * 274 * Looks up the page cache slot at @mapping & @offset. If there is a 275 * page cache page, it is returned locked and with an increased 276 * refcount. 277 * 278 * Otherwise, %NULL is returned. 279 * 280 * find_lock_page() may sleep. 281 */ 282 static inline struct page *find_lock_page(struct address_space *mapping, 283 pgoff_t offset) 284 { 285 return pagecache_get_page(mapping, offset, FGP_LOCK, 0); 286 } 287 288 /** 289 * find_or_create_page - locate or add a pagecache page 290 * @mapping: the page's address_space 291 * @index: the page's index into the mapping 292 * @gfp_mask: page allocation mode 293 * 294 * Looks up the page cache slot at @mapping & @offset. If there is a 295 * page cache page, it is returned locked and with an increased 296 * refcount. 297 * 298 * If the page is not present, a new page is allocated using @gfp_mask 299 * and added to the page cache and the VM's LRU list. The page is 300 * returned locked and with an increased refcount. 301 * 302 * On memory exhaustion, %NULL is returned. 303 * 304 * find_or_create_page() may sleep, even if @gfp_flags specifies an 305 * atomic allocation! 306 */ 307 static inline struct page *find_or_create_page(struct address_space *mapping, 308 pgoff_t offset, gfp_t gfp_mask) 309 { 310 return pagecache_get_page(mapping, offset, 311 FGP_LOCK|FGP_ACCESSED|FGP_CREAT, 312 gfp_mask); 313 } 314 315 /** 316 * grab_cache_page_nowait - returns locked page at given index in given cache 317 * @mapping: target address_space 318 * @index: the page index 319 * 320 * Same as grab_cache_page(), but do not wait if the page is unavailable. 321 * This is intended for speculative data generators, where the data can 322 * be regenerated if the page couldn't be grabbed. This routine should 323 * be safe to call while holding the lock for another page. 324 * 325 * Clear __GFP_FS when allocating the page to avoid recursion into the fs 326 * and deadlock against the caller's locked page. 327 */ 328 static inline struct page *grab_cache_page_nowait(struct address_space *mapping, 329 pgoff_t index) 330 { 331 return pagecache_get_page(mapping, index, 332 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT, 333 mapping_gfp_mask(mapping)); 334 } 335 336 static inline struct page *find_subpage(struct page *page, pgoff_t offset) 337 { 338 unsigned long mask; 339 340 if (PageHuge(page)) 341 return page; 342 343 VM_BUG_ON_PAGE(PageTail(page), page); 344 345 mask = (1UL << compound_order(page)) - 1; 346 return page + (offset & mask); 347 } 348 349 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset); 350 struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset); 351 unsigned find_get_entries(struct address_space *mapping, pgoff_t start, 352 unsigned int nr_entries, struct page **entries, 353 pgoff_t *indices); 354 unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start, 355 pgoff_t end, unsigned int nr_pages, 356 struct page **pages); 357 static inline unsigned find_get_pages(struct address_space *mapping, 358 pgoff_t *start, unsigned int nr_pages, 359 struct page **pages) 360 { 361 return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages, 362 pages); 363 } 364 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, 365 unsigned int nr_pages, struct page **pages); 366 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index, 367 pgoff_t end, xa_mark_t tag, unsigned int nr_pages, 368 struct page **pages); 369 static inline unsigned find_get_pages_tag(struct address_space *mapping, 370 pgoff_t *index, xa_mark_t tag, unsigned int nr_pages, 371 struct page **pages) 372 { 373 return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag, 374 nr_pages, pages); 375 } 376 377 struct page *grab_cache_page_write_begin(struct address_space *mapping, 378 pgoff_t index, unsigned flags); 379 380 /* 381 * Returns locked page at given index in given cache, creating it if needed. 382 */ 383 static inline struct page *grab_cache_page(struct address_space *mapping, 384 pgoff_t index) 385 { 386 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); 387 } 388 389 extern struct page * read_cache_page(struct address_space *mapping, 390 pgoff_t index, filler_t *filler, void *data); 391 extern struct page * read_cache_page_gfp(struct address_space *mapping, 392 pgoff_t index, gfp_t gfp_mask); 393 extern int read_cache_pages(struct address_space *mapping, 394 struct list_head *pages, filler_t *filler, void *data); 395 396 static inline struct page *read_mapping_page(struct address_space *mapping, 397 pgoff_t index, void *data) 398 { 399 filler_t *filler = (filler_t *)mapping->a_ops->readpage; 400 return read_cache_page(mapping, index, filler, data); 401 } 402 403 /* 404 * Get index of the page with in radix-tree 405 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE) 406 */ 407 static inline pgoff_t page_to_index(struct page *page) 408 { 409 pgoff_t pgoff; 410 411 if (likely(!PageTransTail(page))) 412 return page->index; 413 414 /* 415 * We don't initialize ->index for tail pages: calculate based on 416 * head page 417 */ 418 pgoff = compound_head(page)->index; 419 pgoff += page - compound_head(page); 420 return pgoff; 421 } 422 423 /* 424 * Get the offset in PAGE_SIZE. 425 * (TODO: hugepage should have ->index in PAGE_SIZE) 426 */ 427 static inline pgoff_t page_to_pgoff(struct page *page) 428 { 429 if (unlikely(PageHeadHuge(page))) 430 return page->index << compound_order(page); 431 432 return page_to_index(page); 433 } 434 435 /* 436 * Return byte-offset into filesystem object for page. 437 */ 438 static inline loff_t page_offset(struct page *page) 439 { 440 return ((loff_t)page->index) << PAGE_SHIFT; 441 } 442 443 static inline loff_t page_file_offset(struct page *page) 444 { 445 return ((loff_t)page_index(page)) << PAGE_SHIFT; 446 } 447 448 extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma, 449 unsigned long address); 450 451 static inline pgoff_t linear_page_index(struct vm_area_struct *vma, 452 unsigned long address) 453 { 454 pgoff_t pgoff; 455 if (unlikely(is_vm_hugetlb_page(vma))) 456 return linear_hugepage_index(vma, address); 457 pgoff = (address - vma->vm_start) >> PAGE_SHIFT; 458 pgoff += vma->vm_pgoff; 459 return pgoff; 460 } 461 462 extern void __lock_page(struct page *page); 463 extern int __lock_page_killable(struct page *page); 464 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, 465 unsigned int flags); 466 extern void unlock_page(struct page *page); 467 468 static inline int trylock_page(struct page *page) 469 { 470 page = compound_head(page); 471 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags))); 472 } 473 474 /* 475 * lock_page may only be called if we have the page's inode pinned. 476 */ 477 static inline void lock_page(struct page *page) 478 { 479 might_sleep(); 480 if (!trylock_page(page)) 481 __lock_page(page); 482 } 483 484 /* 485 * lock_page_killable is like lock_page but can be interrupted by fatal 486 * signals. It returns 0 if it locked the page and -EINTR if it was 487 * killed while waiting. 488 */ 489 static inline int lock_page_killable(struct page *page) 490 { 491 might_sleep(); 492 if (!trylock_page(page)) 493 return __lock_page_killable(page); 494 return 0; 495 } 496 497 /* 498 * lock_page_or_retry - Lock the page, unless this would block and the 499 * caller indicated that it can handle a retry. 500 * 501 * Return value and mmap_sem implications depend on flags; see 502 * __lock_page_or_retry(). 503 */ 504 static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm, 505 unsigned int flags) 506 { 507 might_sleep(); 508 return trylock_page(page) || __lock_page_or_retry(page, mm, flags); 509 } 510 511 /* 512 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc., 513 * and should not be used directly. 514 */ 515 extern void wait_on_page_bit(struct page *page, int bit_nr); 516 extern int wait_on_page_bit_killable(struct page *page, int bit_nr); 517 518 /* 519 * Wait for a page to be unlocked. 520 * 521 * This must be called with the caller "holding" the page, 522 * ie with increased "page->count" so that the page won't 523 * go away during the wait.. 524 */ 525 static inline void wait_on_page_locked(struct page *page) 526 { 527 if (PageLocked(page)) 528 wait_on_page_bit(compound_head(page), PG_locked); 529 } 530 531 static inline int wait_on_page_locked_killable(struct page *page) 532 { 533 if (!PageLocked(page)) 534 return 0; 535 return wait_on_page_bit_killable(compound_head(page), PG_locked); 536 } 537 538 extern void put_and_wait_on_page_locked(struct page *page); 539 540 void wait_on_page_writeback(struct page *page); 541 extern void end_page_writeback(struct page *page); 542 void wait_for_stable_page(struct page *page); 543 544 void page_endio(struct page *page, bool is_write, int err); 545 546 /* 547 * Add an arbitrary waiter to a page's wait queue 548 */ 549 extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter); 550 551 /* 552 * Fault everything in given userspace address range in. 553 */ 554 static inline int fault_in_pages_writeable(char __user *uaddr, int size) 555 { 556 char __user *end = uaddr + size - 1; 557 558 if (unlikely(size == 0)) 559 return 0; 560 561 if (unlikely(uaddr > end)) 562 return -EFAULT; 563 /* 564 * Writing zeroes into userspace here is OK, because we know that if 565 * the zero gets there, we'll be overwriting it. 566 */ 567 do { 568 if (unlikely(__put_user(0, uaddr) != 0)) 569 return -EFAULT; 570 uaddr += PAGE_SIZE; 571 } while (uaddr <= end); 572 573 /* Check whether the range spilled into the next page. */ 574 if (((unsigned long)uaddr & PAGE_MASK) == 575 ((unsigned long)end & PAGE_MASK)) 576 return __put_user(0, end); 577 578 return 0; 579 } 580 581 static inline int fault_in_pages_readable(const char __user *uaddr, int size) 582 { 583 volatile char c; 584 const char __user *end = uaddr + size - 1; 585 586 if (unlikely(size == 0)) 587 return 0; 588 589 if (unlikely(uaddr > end)) 590 return -EFAULT; 591 592 do { 593 if (unlikely(__get_user(c, uaddr) != 0)) 594 return -EFAULT; 595 uaddr += PAGE_SIZE; 596 } while (uaddr <= end); 597 598 /* Check whether the range spilled into the next page. */ 599 if (((unsigned long)uaddr & PAGE_MASK) == 600 ((unsigned long)end & PAGE_MASK)) { 601 return __get_user(c, end); 602 } 603 604 (void)c; 605 return 0; 606 } 607 608 int add_to_page_cache_locked(struct page *page, struct address_space *mapping, 609 pgoff_t index, gfp_t gfp_mask); 610 int add_to_page_cache_lru(struct page *page, struct address_space *mapping, 611 pgoff_t index, gfp_t gfp_mask); 612 extern void delete_from_page_cache(struct page *page); 613 extern void __delete_from_page_cache(struct page *page, void *shadow); 614 int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask); 615 void delete_from_page_cache_batch(struct address_space *mapping, 616 struct pagevec *pvec); 617 618 /* 619 * Like add_to_page_cache_locked, but used to add newly allocated pages: 620 * the page is new, so we can just run __SetPageLocked() against it. 621 */ 622 static inline int add_to_page_cache(struct page *page, 623 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) 624 { 625 int error; 626 627 __SetPageLocked(page); 628 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); 629 if (unlikely(error)) 630 __ClearPageLocked(page); 631 return error; 632 } 633 634 static inline unsigned long dir_pages(struct inode *inode) 635 { 636 return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >> 637 PAGE_SHIFT; 638 } 639 640 #endif /* _LINUX_PAGEMAP_H */ 641