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 bool mapping_unevictable(struct address_space *mapping) 74 { 75 return mapping && test_bit(AS_UNEVICTABLE, &mapping->flags); 76 } 77 78 static inline void mapping_set_exiting(struct address_space *mapping) 79 { 80 set_bit(AS_EXITING, &mapping->flags); 81 } 82 83 static inline int mapping_exiting(struct address_space *mapping) 84 { 85 return test_bit(AS_EXITING, &mapping->flags); 86 } 87 88 static inline void mapping_set_no_writeback_tags(struct address_space *mapping) 89 { 90 set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); 91 } 92 93 static inline int mapping_use_writeback_tags(struct address_space *mapping) 94 { 95 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); 96 } 97 98 static inline gfp_t mapping_gfp_mask(struct address_space * mapping) 99 { 100 return mapping->gfp_mask; 101 } 102 103 /* Restricts the given gfp_mask to what the mapping allows. */ 104 static inline gfp_t mapping_gfp_constraint(struct address_space *mapping, 105 gfp_t gfp_mask) 106 { 107 return mapping_gfp_mask(mapping) & gfp_mask; 108 } 109 110 /* 111 * This is non-atomic. Only to be used before the mapping is activated. 112 * Probably needs a barrier... 113 */ 114 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) 115 { 116 m->gfp_mask = mask; 117 } 118 119 void release_pages(struct page **pages, int nr); 120 121 /* 122 * speculatively take a reference to a page. 123 * If the page is free (_refcount == 0), then _refcount is untouched, and 0 124 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned. 125 * 126 * This function must be called inside the same rcu_read_lock() section as has 127 * been used to lookup the page in the pagecache radix-tree (or page table): 128 * this allows allocators to use a synchronize_rcu() to stabilize _refcount. 129 * 130 * Unless an RCU grace period has passed, the count of all pages coming out 131 * of the allocator must be considered unstable. page_count may return higher 132 * than expected, and put_page must be able to do the right thing when the 133 * page has been finished with, no matter what it is subsequently allocated 134 * for (because put_page is what is used here to drop an invalid speculative 135 * reference). 136 * 137 * This is the interesting part of the lockless pagecache (and lockless 138 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) 139 * has the following pattern: 140 * 1. find page in radix tree 141 * 2. conditionally increment refcount 142 * 3. check the page is still in pagecache (if no, goto 1) 143 * 144 * Remove-side that cares about stability of _refcount (eg. reclaim) has the 145 * following (with the i_pages lock held): 146 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) 147 * B. remove page from pagecache 148 * C. free the page 149 * 150 * There are 2 critical interleavings that matter: 151 * - 2 runs before A: in this case, A sees elevated refcount and bails out 152 * - A runs before 2: in this case, 2 sees zero refcount and retries; 153 * subsequently, B will complete and 1 will find no page, causing the 154 * lookup to return NULL. 155 * 156 * It is possible that between 1 and 2, the page is removed then the exact same 157 * page is inserted into the same position in pagecache. That's OK: the 158 * old find_get_page using a lock could equally have run before or after 159 * such a re-insertion, depending on order that locks are granted. 160 * 161 * Lookups racing against pagecache insertion isn't a big problem: either 1 162 * will find the page or it will not. Likewise, the old find_get_page could run 163 * either before the insertion or afterwards, depending on timing. 164 */ 165 static inline int __page_cache_add_speculative(struct page *page, int count) 166 { 167 #ifdef CONFIG_TINY_RCU 168 # ifdef CONFIG_PREEMPT_COUNT 169 VM_BUG_ON(!in_atomic() && !irqs_disabled()); 170 # endif 171 /* 172 * Preempt must be disabled here - we rely on rcu_read_lock doing 173 * this for us. 174 * 175 * Pagecache won't be truncated from interrupt context, so if we have 176 * found a page in the radix tree here, we have pinned its refcount by 177 * disabling preempt, and hence no need for the "speculative get" that 178 * SMP requires. 179 */ 180 VM_BUG_ON_PAGE(page_count(page) == 0, page); 181 page_ref_add(page, count); 182 183 #else 184 if (unlikely(!page_ref_add_unless(page, count, 0))) { 185 /* 186 * Either the page has been freed, or will be freed. 187 * In either case, retry here and the caller should 188 * do the right thing (see comments above). 189 */ 190 return 0; 191 } 192 #endif 193 VM_BUG_ON_PAGE(PageTail(page), page); 194 195 return 1; 196 } 197 198 static inline int page_cache_get_speculative(struct page *page) 199 { 200 return __page_cache_add_speculative(page, 1); 201 } 202 203 static inline int page_cache_add_speculative(struct page *page, int count) 204 { 205 return __page_cache_add_speculative(page, count); 206 } 207 208 #ifdef CONFIG_NUMA 209 extern struct page *__page_cache_alloc(gfp_t gfp); 210 #else 211 static inline struct page *__page_cache_alloc(gfp_t gfp) 212 { 213 return alloc_pages(gfp, 0); 214 } 215 #endif 216 217 static inline struct page *page_cache_alloc(struct address_space *x) 218 { 219 return __page_cache_alloc(mapping_gfp_mask(x)); 220 } 221 222 static inline gfp_t readahead_gfp_mask(struct address_space *x) 223 { 224 return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN; 225 } 226 227 typedef int filler_t(void *, struct page *); 228 229 pgoff_t page_cache_next_miss(struct address_space *mapping, 230 pgoff_t index, unsigned long max_scan); 231 pgoff_t page_cache_prev_miss(struct address_space *mapping, 232 pgoff_t index, unsigned long max_scan); 233 234 #define FGP_ACCESSED 0x00000001 235 #define FGP_LOCK 0x00000002 236 #define FGP_CREAT 0x00000004 237 #define FGP_WRITE 0x00000008 238 #define FGP_NOFS 0x00000010 239 #define FGP_NOWAIT 0x00000020 240 #define FGP_FOR_MMAP 0x00000040 241 242 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, 243 int fgp_flags, gfp_t cache_gfp_mask); 244 245 /** 246 * find_get_page - find and get a page reference 247 * @mapping: the address_space to search 248 * @offset: the page index 249 * 250 * Looks up the page cache slot at @mapping & @offset. If there is a 251 * page cache page, it is returned with an increased refcount. 252 * 253 * Otherwise, %NULL is returned. 254 */ 255 static inline struct page *find_get_page(struct address_space *mapping, 256 pgoff_t offset) 257 { 258 return pagecache_get_page(mapping, offset, 0, 0); 259 } 260 261 static inline struct page *find_get_page_flags(struct address_space *mapping, 262 pgoff_t offset, int fgp_flags) 263 { 264 return pagecache_get_page(mapping, offset, fgp_flags, 0); 265 } 266 267 /** 268 * find_lock_page - locate, pin and lock a pagecache page 269 * @mapping: the address_space to search 270 * @offset: the page index 271 * 272 * Looks up the page cache slot at @mapping & @offset. If there is a 273 * page cache page, it is returned locked and with an increased 274 * refcount. 275 * 276 * Otherwise, %NULL is returned. 277 * 278 * find_lock_page() may sleep. 279 */ 280 static inline struct page *find_lock_page(struct address_space *mapping, 281 pgoff_t offset) 282 { 283 return pagecache_get_page(mapping, offset, FGP_LOCK, 0); 284 } 285 286 /** 287 * find_or_create_page - locate or add a pagecache page 288 * @mapping: the page's address_space 289 * @index: the page's index into the mapping 290 * @gfp_mask: page allocation mode 291 * 292 * Looks up the page cache slot at @mapping & @offset. If there is a 293 * page cache page, it is returned locked and with an increased 294 * refcount. 295 * 296 * If the page is not present, a new page is allocated using @gfp_mask 297 * and added to the page cache and the VM's LRU list. The page is 298 * returned locked and with an increased refcount. 299 * 300 * On memory exhaustion, %NULL is returned. 301 * 302 * find_or_create_page() may sleep, even if @gfp_flags specifies an 303 * atomic allocation! 304 */ 305 static inline struct page *find_or_create_page(struct address_space *mapping, 306 pgoff_t index, gfp_t gfp_mask) 307 { 308 return pagecache_get_page(mapping, index, 309 FGP_LOCK|FGP_ACCESSED|FGP_CREAT, 310 gfp_mask); 311 } 312 313 /** 314 * grab_cache_page_nowait - returns locked page at given index in given cache 315 * @mapping: target address_space 316 * @index: the page index 317 * 318 * Same as grab_cache_page(), but do not wait if the page is unavailable. 319 * This is intended for speculative data generators, where the data can 320 * be regenerated if the page couldn't be grabbed. This routine should 321 * be safe to call while holding the lock for another page. 322 * 323 * Clear __GFP_FS when allocating the page to avoid recursion into the fs 324 * and deadlock against the caller's locked page. 325 */ 326 static inline struct page *grab_cache_page_nowait(struct address_space *mapping, 327 pgoff_t index) 328 { 329 return pagecache_get_page(mapping, index, 330 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT, 331 mapping_gfp_mask(mapping)); 332 } 333 334 /* 335 * Given the page we found in the page cache, return the page corresponding 336 * to this index in the file 337 */ 338 static inline struct page *find_subpage(struct page *head, pgoff_t index) 339 { 340 /* HugeTLBfs wants the head page regardless */ 341 if (PageHuge(head)) 342 return head; 343 344 return head + (index & (hpage_nr_pages(head) - 1)); 345 } 346 347 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset); 348 struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset); 349 unsigned find_get_entries(struct address_space *mapping, pgoff_t start, 350 unsigned int nr_entries, struct page **entries, 351 pgoff_t *indices); 352 unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start, 353 pgoff_t end, unsigned int nr_pages, 354 struct page **pages); 355 static inline unsigned find_get_pages(struct address_space *mapping, 356 pgoff_t *start, unsigned int nr_pages, 357 struct page **pages) 358 { 359 return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages, 360 pages); 361 } 362 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, 363 unsigned int nr_pages, struct page **pages); 364 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index, 365 pgoff_t end, xa_mark_t tag, unsigned int nr_pages, 366 struct page **pages); 367 static inline unsigned find_get_pages_tag(struct address_space *mapping, 368 pgoff_t *index, xa_mark_t tag, unsigned int nr_pages, 369 struct page **pages) 370 { 371 return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag, 372 nr_pages, pages); 373 } 374 375 struct page *grab_cache_page_write_begin(struct address_space *mapping, 376 pgoff_t index, unsigned flags); 377 378 /* 379 * Returns locked page at given index in given cache, creating it if needed. 380 */ 381 static inline struct page *grab_cache_page(struct address_space *mapping, 382 pgoff_t index) 383 { 384 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); 385 } 386 387 extern struct page * read_cache_page(struct address_space *mapping, 388 pgoff_t index, filler_t *filler, void *data); 389 extern struct page * read_cache_page_gfp(struct address_space *mapping, 390 pgoff_t index, gfp_t gfp_mask); 391 extern int read_cache_pages(struct address_space *mapping, 392 struct list_head *pages, filler_t *filler, void *data); 393 394 static inline struct page *read_mapping_page(struct address_space *mapping, 395 pgoff_t index, void *data) 396 { 397 return read_cache_page(mapping, index, NULL, data); 398 } 399 400 /* 401 * Get index of the page with in radix-tree 402 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE) 403 */ 404 static inline pgoff_t page_to_index(struct page *page) 405 { 406 pgoff_t pgoff; 407 408 if (likely(!PageTransTail(page))) 409 return page->index; 410 411 /* 412 * We don't initialize ->index for tail pages: calculate based on 413 * head page 414 */ 415 pgoff = compound_head(page)->index; 416 pgoff += page - compound_head(page); 417 return pgoff; 418 } 419 420 /* 421 * Get the offset in PAGE_SIZE. 422 * (TODO: hugepage should have ->index in PAGE_SIZE) 423 */ 424 static inline pgoff_t page_to_pgoff(struct page *page) 425 { 426 if (unlikely(PageHeadHuge(page))) 427 return page->index << compound_order(page); 428 429 return page_to_index(page); 430 } 431 432 /* 433 * Return byte-offset into filesystem object for page. 434 */ 435 static inline loff_t page_offset(struct page *page) 436 { 437 return ((loff_t)page->index) << PAGE_SHIFT; 438 } 439 440 static inline loff_t page_file_offset(struct page *page) 441 { 442 return ((loff_t)page_index(page)) << PAGE_SHIFT; 443 } 444 445 extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma, 446 unsigned long address); 447 448 static inline pgoff_t linear_page_index(struct vm_area_struct *vma, 449 unsigned long address) 450 { 451 pgoff_t pgoff; 452 if (unlikely(is_vm_hugetlb_page(vma))) 453 return linear_hugepage_index(vma, address); 454 pgoff = (address - vma->vm_start) >> PAGE_SHIFT; 455 pgoff += vma->vm_pgoff; 456 return pgoff; 457 } 458 459 extern void __lock_page(struct page *page); 460 extern int __lock_page_killable(struct page *page); 461 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, 462 unsigned int flags); 463 extern void unlock_page(struct page *page); 464 465 /* 466 * Return true if the page was successfully locked 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 /** 641 * page_mkwrite_check_truncate - check if page was truncated 642 * @page: the page to check 643 * @inode: the inode to check the page against 644 * 645 * Returns the number of bytes in the page up to EOF, 646 * or -EFAULT if the page was truncated. 647 */ 648 static inline int page_mkwrite_check_truncate(struct page *page, 649 struct inode *inode) 650 { 651 loff_t size = i_size_read(inode); 652 pgoff_t index = size >> PAGE_SHIFT; 653 int offset = offset_in_page(size); 654 655 if (page->mapping != inode->i_mapping) 656 return -EFAULT; 657 658 /* page is wholly inside EOF */ 659 if (page->index < index) 660 return PAGE_SIZE; 661 /* page is wholly past EOF */ 662 if (page->index > index || !offset) 663 return -EFAULT; 664 /* page is partially inside EOF */ 665 return offset; 666 } 667 668 #endif /* _LINUX_PAGEMAP_H */ 669