1 /* 2 * linux/mm/filemap.c 3 * 4 * Copyright (C) 1994-1999 Linus Torvalds 5 */ 6 7 /* 8 * This file handles the generic file mmap semantics used by 9 * most "normal" filesystems (but you don't /have/ to use this: 10 * the NFS filesystem used to do this differently, for example) 11 */ 12 #include <linux/config.h> 13 #include <linux/module.h> 14 #include <linux/slab.h> 15 #include <linux/compiler.h> 16 #include <linux/fs.h> 17 #include <linux/aio.h> 18 #include <linux/kernel_stat.h> 19 #include <linux/mm.h> 20 #include <linux/swap.h> 21 #include <linux/mman.h> 22 #include <linux/pagemap.h> 23 #include <linux/file.h> 24 #include <linux/uio.h> 25 #include <linux/hash.h> 26 #include <linux/writeback.h> 27 #include <linux/pagevec.h> 28 #include <linux/blkdev.h> 29 #include <linux/security.h> 30 #include <linux/syscalls.h> 31 #include "filemap.h" 32 /* 33 * FIXME: remove all knowledge of the buffer layer from the core VM 34 */ 35 #include <linux/buffer_head.h> /* for generic_osync_inode */ 36 37 #include <asm/uaccess.h> 38 #include <asm/mman.h> 39 40 static ssize_t 41 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, 42 loff_t offset, unsigned long nr_segs); 43 44 /* 45 * Shared mappings implemented 30.11.1994. It's not fully working yet, 46 * though. 47 * 48 * Shared mappings now work. 15.8.1995 Bruno. 49 * 50 * finished 'unifying' the page and buffer cache and SMP-threaded the 51 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> 52 * 53 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> 54 */ 55 56 /* 57 * Lock ordering: 58 * 59 * ->i_mmap_lock (vmtruncate) 60 * ->private_lock (__free_pte->__set_page_dirty_buffers) 61 * ->swap_lock (exclusive_swap_page, others) 62 * ->mapping->tree_lock 63 * 64 * ->i_sem 65 * ->i_mmap_lock (truncate->unmap_mapping_range) 66 * 67 * ->mmap_sem 68 * ->i_mmap_lock 69 * ->page_table_lock or pte_lock (various, mainly in memory.c) 70 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) 71 * 72 * ->mmap_sem 73 * ->lock_page (access_process_vm) 74 * 75 * ->mmap_sem 76 * ->i_sem (msync) 77 * 78 * ->i_sem 79 * ->i_alloc_sem (various) 80 * 81 * ->inode_lock 82 * ->sb_lock (fs/fs-writeback.c) 83 * ->mapping->tree_lock (__sync_single_inode) 84 * 85 * ->i_mmap_lock 86 * ->anon_vma.lock (vma_adjust) 87 * 88 * ->anon_vma.lock 89 * ->page_table_lock or pte_lock (anon_vma_prepare and various) 90 * 91 * ->page_table_lock or pte_lock 92 * ->swap_lock (try_to_unmap_one) 93 * ->private_lock (try_to_unmap_one) 94 * ->tree_lock (try_to_unmap_one) 95 * ->zone.lru_lock (follow_page->mark_page_accessed) 96 * ->private_lock (page_remove_rmap->set_page_dirty) 97 * ->tree_lock (page_remove_rmap->set_page_dirty) 98 * ->inode_lock (page_remove_rmap->set_page_dirty) 99 * ->inode_lock (zap_pte_range->set_page_dirty) 100 * ->private_lock (zap_pte_range->__set_page_dirty_buffers) 101 * 102 * ->task->proc_lock 103 * ->dcache_lock (proc_pid_lookup) 104 */ 105 106 /* 107 * Remove a page from the page cache and free it. Caller has to make 108 * sure the page is locked and that nobody else uses it - or that usage 109 * is safe. The caller must hold a write_lock on the mapping's tree_lock. 110 */ 111 void __remove_from_page_cache(struct page *page) 112 { 113 struct address_space *mapping = page->mapping; 114 115 radix_tree_delete(&mapping->page_tree, page->index); 116 page->mapping = NULL; 117 mapping->nrpages--; 118 pagecache_acct(-1); 119 } 120 121 void remove_from_page_cache(struct page *page) 122 { 123 struct address_space *mapping = page->mapping; 124 125 BUG_ON(!PageLocked(page)); 126 127 write_lock_irq(&mapping->tree_lock); 128 __remove_from_page_cache(page); 129 write_unlock_irq(&mapping->tree_lock); 130 } 131 132 static int sync_page(void *word) 133 { 134 struct address_space *mapping; 135 struct page *page; 136 137 page = container_of((page_flags_t *)word, struct page, flags); 138 139 /* 140 * page_mapping() is being called without PG_locked held. 141 * Some knowledge of the state and use of the page is used to 142 * reduce the requirements down to a memory barrier. 143 * The danger here is of a stale page_mapping() return value 144 * indicating a struct address_space different from the one it's 145 * associated with when it is associated with one. 146 * After smp_mb(), it's either the correct page_mapping() for 147 * the page, or an old page_mapping() and the page's own 148 * page_mapping() has gone NULL. 149 * The ->sync_page() address_space operation must tolerate 150 * page_mapping() going NULL. By an amazing coincidence, 151 * this comes about because none of the users of the page 152 * in the ->sync_page() methods make essential use of the 153 * page_mapping(), merely passing the page down to the backing 154 * device's unplug functions when it's non-NULL, which in turn 155 * ignore it for all cases but swap, where only page_private(page) is 156 * of interest. When page_mapping() does go NULL, the entire 157 * call stack gracefully ignores the page and returns. 158 * -- wli 159 */ 160 smp_mb(); 161 mapping = page_mapping(page); 162 if (mapping && mapping->a_ops && mapping->a_ops->sync_page) 163 mapping->a_ops->sync_page(page); 164 io_schedule(); 165 return 0; 166 } 167 168 /** 169 * filemap_fdatawrite_range - start writeback against all of a mapping's 170 * dirty pages that lie within the byte offsets <start, end> 171 * @mapping: address space structure to write 172 * @start: offset in bytes where the range starts 173 * @end: offset in bytes where the range ends 174 * @sync_mode: enable synchronous operation 175 * 176 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as 177 * opposed to a regular memory * cleansing writeback. The difference between 178 * these two operations is that if a dirty page/buffer is encountered, it must 179 * be waited upon, and not just skipped over. 180 */ 181 static int __filemap_fdatawrite_range(struct address_space *mapping, 182 loff_t start, loff_t end, int sync_mode) 183 { 184 int ret; 185 struct writeback_control wbc = { 186 .sync_mode = sync_mode, 187 .nr_to_write = mapping->nrpages * 2, 188 .start = start, 189 .end = end, 190 }; 191 192 if (!mapping_cap_writeback_dirty(mapping)) 193 return 0; 194 195 ret = do_writepages(mapping, &wbc); 196 return ret; 197 } 198 199 static inline int __filemap_fdatawrite(struct address_space *mapping, 200 int sync_mode) 201 { 202 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode); 203 } 204 205 int filemap_fdatawrite(struct address_space *mapping) 206 { 207 return __filemap_fdatawrite(mapping, WB_SYNC_ALL); 208 } 209 EXPORT_SYMBOL(filemap_fdatawrite); 210 211 static int filemap_fdatawrite_range(struct address_space *mapping, 212 loff_t start, loff_t end) 213 { 214 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); 215 } 216 217 /* 218 * This is a mostly non-blocking flush. Not suitable for data-integrity 219 * purposes - I/O may not be started against all dirty pages. 220 */ 221 int filemap_flush(struct address_space *mapping) 222 { 223 return __filemap_fdatawrite(mapping, WB_SYNC_NONE); 224 } 225 EXPORT_SYMBOL(filemap_flush); 226 227 /* 228 * Wait for writeback to complete against pages indexed by start->end 229 * inclusive 230 */ 231 static int wait_on_page_writeback_range(struct address_space *mapping, 232 pgoff_t start, pgoff_t end) 233 { 234 struct pagevec pvec; 235 int nr_pages; 236 int ret = 0; 237 pgoff_t index; 238 239 if (end < start) 240 return 0; 241 242 pagevec_init(&pvec, 0); 243 index = start; 244 while ((index <= end) && 245 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, 246 PAGECACHE_TAG_WRITEBACK, 247 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { 248 unsigned i; 249 250 for (i = 0; i < nr_pages; i++) { 251 struct page *page = pvec.pages[i]; 252 253 /* until radix tree lookup accepts end_index */ 254 if (page->index > end) 255 continue; 256 257 wait_on_page_writeback(page); 258 if (PageError(page)) 259 ret = -EIO; 260 } 261 pagevec_release(&pvec); 262 cond_resched(); 263 } 264 265 /* Check for outstanding write errors */ 266 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) 267 ret = -ENOSPC; 268 if (test_and_clear_bit(AS_EIO, &mapping->flags)) 269 ret = -EIO; 270 271 return ret; 272 } 273 274 /* 275 * Write and wait upon all the pages in the passed range. This is a "data 276 * integrity" operation. It waits upon in-flight writeout before starting and 277 * waiting upon new writeout. If there was an IO error, return it. 278 * 279 * We need to re-take i_sem during the generic_osync_inode list walk because 280 * it is otherwise livelockable. 281 */ 282 int sync_page_range(struct inode *inode, struct address_space *mapping, 283 loff_t pos, size_t count) 284 { 285 pgoff_t start = pos >> PAGE_CACHE_SHIFT; 286 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; 287 int ret; 288 289 if (!mapping_cap_writeback_dirty(mapping) || !count) 290 return 0; 291 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); 292 if (ret == 0) { 293 down(&inode->i_sem); 294 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); 295 up(&inode->i_sem); 296 } 297 if (ret == 0) 298 ret = wait_on_page_writeback_range(mapping, start, end); 299 return ret; 300 } 301 EXPORT_SYMBOL(sync_page_range); 302 303 /* 304 * Note: Holding i_sem across sync_page_range_nolock is not a good idea 305 * as it forces O_SYNC writers to different parts of the same file 306 * to be serialised right until io completion. 307 */ 308 static int sync_page_range_nolock(struct inode *inode, 309 struct address_space *mapping, 310 loff_t pos, size_t count) 311 { 312 pgoff_t start = pos >> PAGE_CACHE_SHIFT; 313 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; 314 int ret; 315 316 if (!mapping_cap_writeback_dirty(mapping) || !count) 317 return 0; 318 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); 319 if (ret == 0) 320 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); 321 if (ret == 0) 322 ret = wait_on_page_writeback_range(mapping, start, end); 323 return ret; 324 } 325 326 /** 327 * filemap_fdatawait - walk the list of under-writeback pages of the given 328 * address space and wait for all of them. 329 * 330 * @mapping: address space structure to wait for 331 */ 332 int filemap_fdatawait(struct address_space *mapping) 333 { 334 loff_t i_size = i_size_read(mapping->host); 335 336 if (i_size == 0) 337 return 0; 338 339 return wait_on_page_writeback_range(mapping, 0, 340 (i_size - 1) >> PAGE_CACHE_SHIFT); 341 } 342 EXPORT_SYMBOL(filemap_fdatawait); 343 344 int filemap_write_and_wait(struct address_space *mapping) 345 { 346 int retval = 0; 347 348 if (mapping->nrpages) { 349 retval = filemap_fdatawrite(mapping); 350 if (retval == 0) 351 retval = filemap_fdatawait(mapping); 352 } 353 return retval; 354 } 355 356 int filemap_write_and_wait_range(struct address_space *mapping, 357 loff_t lstart, loff_t lend) 358 { 359 int retval = 0; 360 361 if (mapping->nrpages) { 362 retval = __filemap_fdatawrite_range(mapping, lstart, lend, 363 WB_SYNC_ALL); 364 if (retval == 0) 365 retval = wait_on_page_writeback_range(mapping, 366 lstart >> PAGE_CACHE_SHIFT, 367 lend >> PAGE_CACHE_SHIFT); 368 } 369 return retval; 370 } 371 372 /* 373 * This function is used to add newly allocated pagecache pages: 374 * the page is new, so we can just run SetPageLocked() against it. 375 * The other page state flags were set by rmqueue(). 376 * 377 * This function does not add the page to the LRU. The caller must do that. 378 */ 379 int add_to_page_cache(struct page *page, struct address_space *mapping, 380 pgoff_t offset, gfp_t gfp_mask) 381 { 382 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); 383 384 if (error == 0) { 385 write_lock_irq(&mapping->tree_lock); 386 error = radix_tree_insert(&mapping->page_tree, offset, page); 387 if (!error) { 388 page_cache_get(page); 389 SetPageLocked(page); 390 page->mapping = mapping; 391 page->index = offset; 392 mapping->nrpages++; 393 pagecache_acct(1); 394 } 395 write_unlock_irq(&mapping->tree_lock); 396 radix_tree_preload_end(); 397 } 398 return error; 399 } 400 401 EXPORT_SYMBOL(add_to_page_cache); 402 403 int add_to_page_cache_lru(struct page *page, struct address_space *mapping, 404 pgoff_t offset, gfp_t gfp_mask) 405 { 406 int ret = add_to_page_cache(page, mapping, offset, gfp_mask); 407 if (ret == 0) 408 lru_cache_add(page); 409 return ret; 410 } 411 412 /* 413 * In order to wait for pages to become available there must be 414 * waitqueues associated with pages. By using a hash table of 415 * waitqueues where the bucket discipline is to maintain all 416 * waiters on the same queue and wake all when any of the pages 417 * become available, and for the woken contexts to check to be 418 * sure the appropriate page became available, this saves space 419 * at a cost of "thundering herd" phenomena during rare hash 420 * collisions. 421 */ 422 static wait_queue_head_t *page_waitqueue(struct page *page) 423 { 424 const struct zone *zone = page_zone(page); 425 426 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; 427 } 428 429 static inline void wake_up_page(struct page *page, int bit) 430 { 431 __wake_up_bit(page_waitqueue(page), &page->flags, bit); 432 } 433 434 void fastcall wait_on_page_bit(struct page *page, int bit_nr) 435 { 436 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); 437 438 if (test_bit(bit_nr, &page->flags)) 439 __wait_on_bit(page_waitqueue(page), &wait, sync_page, 440 TASK_UNINTERRUPTIBLE); 441 } 442 EXPORT_SYMBOL(wait_on_page_bit); 443 444 /** 445 * unlock_page() - unlock a locked page 446 * 447 * @page: the page 448 * 449 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). 450 * Also wakes sleepers in wait_on_page_writeback() because the wakeup 451 * mechananism between PageLocked pages and PageWriteback pages is shared. 452 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. 453 * 454 * The first mb is necessary to safely close the critical section opened by the 455 * TestSetPageLocked(), the second mb is necessary to enforce ordering between 456 * the clear_bit and the read of the waitqueue (to avoid SMP races with a 457 * parallel wait_on_page_locked()). 458 */ 459 void fastcall unlock_page(struct page *page) 460 { 461 smp_mb__before_clear_bit(); 462 if (!TestClearPageLocked(page)) 463 BUG(); 464 smp_mb__after_clear_bit(); 465 wake_up_page(page, PG_locked); 466 } 467 EXPORT_SYMBOL(unlock_page); 468 469 /* 470 * End writeback against a page. 471 */ 472 void end_page_writeback(struct page *page) 473 { 474 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { 475 if (!test_clear_page_writeback(page)) 476 BUG(); 477 } 478 smp_mb__after_clear_bit(); 479 wake_up_page(page, PG_writeback); 480 } 481 EXPORT_SYMBOL(end_page_writeback); 482 483 /* 484 * Get a lock on the page, assuming we need to sleep to get it. 485 * 486 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some 487 * random driver's requestfn sets TASK_RUNNING, we could busywait. However 488 * chances are that on the second loop, the block layer's plug list is empty, 489 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. 490 */ 491 void fastcall __lock_page(struct page *page) 492 { 493 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); 494 495 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, 496 TASK_UNINTERRUPTIBLE); 497 } 498 EXPORT_SYMBOL(__lock_page); 499 500 /* 501 * a rather lightweight function, finding and getting a reference to a 502 * hashed page atomically. 503 */ 504 struct page * find_get_page(struct address_space *mapping, unsigned long offset) 505 { 506 struct page *page; 507 508 read_lock_irq(&mapping->tree_lock); 509 page = radix_tree_lookup(&mapping->page_tree, offset); 510 if (page) 511 page_cache_get(page); 512 read_unlock_irq(&mapping->tree_lock); 513 return page; 514 } 515 516 EXPORT_SYMBOL(find_get_page); 517 518 /* 519 * Same as above, but trylock it instead of incrementing the count. 520 */ 521 struct page *find_trylock_page(struct address_space *mapping, unsigned long offset) 522 { 523 struct page *page; 524 525 read_lock_irq(&mapping->tree_lock); 526 page = radix_tree_lookup(&mapping->page_tree, offset); 527 if (page && TestSetPageLocked(page)) 528 page = NULL; 529 read_unlock_irq(&mapping->tree_lock); 530 return page; 531 } 532 533 EXPORT_SYMBOL(find_trylock_page); 534 535 /** 536 * find_lock_page - locate, pin and lock a pagecache page 537 * 538 * @mapping: the address_space to search 539 * @offset: the page index 540 * 541 * Locates the desired pagecache page, locks it, increments its reference 542 * count and returns its address. 543 * 544 * Returns zero if the page was not present. find_lock_page() may sleep. 545 */ 546 struct page *find_lock_page(struct address_space *mapping, 547 unsigned long offset) 548 { 549 struct page *page; 550 551 read_lock_irq(&mapping->tree_lock); 552 repeat: 553 page = radix_tree_lookup(&mapping->page_tree, offset); 554 if (page) { 555 page_cache_get(page); 556 if (TestSetPageLocked(page)) { 557 read_unlock_irq(&mapping->tree_lock); 558 lock_page(page); 559 read_lock_irq(&mapping->tree_lock); 560 561 /* Has the page been truncated while we slept? */ 562 if (page->mapping != mapping || page->index != offset) { 563 unlock_page(page); 564 page_cache_release(page); 565 goto repeat; 566 } 567 } 568 } 569 read_unlock_irq(&mapping->tree_lock); 570 return page; 571 } 572 573 EXPORT_SYMBOL(find_lock_page); 574 575 /** 576 * find_or_create_page - locate or add a pagecache page 577 * 578 * @mapping: the page's address_space 579 * @index: the page's index into the mapping 580 * @gfp_mask: page allocation mode 581 * 582 * Locates a page in the pagecache. If the page is not present, a new page 583 * is allocated using @gfp_mask and is added to the pagecache and to the VM's 584 * LRU list. The returned page is locked and has its reference count 585 * incremented. 586 * 587 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic 588 * allocation! 589 * 590 * find_or_create_page() returns the desired page's address, or zero on 591 * memory exhaustion. 592 */ 593 struct page *find_or_create_page(struct address_space *mapping, 594 unsigned long index, gfp_t gfp_mask) 595 { 596 struct page *page, *cached_page = NULL; 597 int err; 598 repeat: 599 page = find_lock_page(mapping, index); 600 if (!page) { 601 if (!cached_page) { 602 cached_page = alloc_page(gfp_mask); 603 if (!cached_page) 604 return NULL; 605 } 606 err = add_to_page_cache_lru(cached_page, mapping, 607 index, gfp_mask); 608 if (!err) { 609 page = cached_page; 610 cached_page = NULL; 611 } else if (err == -EEXIST) 612 goto repeat; 613 } 614 if (cached_page) 615 page_cache_release(cached_page); 616 return page; 617 } 618 619 EXPORT_SYMBOL(find_or_create_page); 620 621 /** 622 * find_get_pages - gang pagecache lookup 623 * @mapping: The address_space to search 624 * @start: The starting page index 625 * @nr_pages: The maximum number of pages 626 * @pages: Where the resulting pages are placed 627 * 628 * find_get_pages() will search for and return a group of up to 629 * @nr_pages pages in the mapping. The pages are placed at @pages. 630 * find_get_pages() takes a reference against the returned pages. 631 * 632 * The search returns a group of mapping-contiguous pages with ascending 633 * indexes. There may be holes in the indices due to not-present pages. 634 * 635 * find_get_pages() returns the number of pages which were found. 636 */ 637 unsigned find_get_pages(struct address_space *mapping, pgoff_t start, 638 unsigned int nr_pages, struct page **pages) 639 { 640 unsigned int i; 641 unsigned int ret; 642 643 read_lock_irq(&mapping->tree_lock); 644 ret = radix_tree_gang_lookup(&mapping->page_tree, 645 (void **)pages, start, nr_pages); 646 for (i = 0; i < ret; i++) 647 page_cache_get(pages[i]); 648 read_unlock_irq(&mapping->tree_lock); 649 return ret; 650 } 651 652 /* 653 * Like find_get_pages, except we only return pages which are tagged with 654 * `tag'. We update *index to index the next page for the traversal. 655 */ 656 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, 657 int tag, unsigned int nr_pages, struct page **pages) 658 { 659 unsigned int i; 660 unsigned int ret; 661 662 read_lock_irq(&mapping->tree_lock); 663 ret = radix_tree_gang_lookup_tag(&mapping->page_tree, 664 (void **)pages, *index, nr_pages, tag); 665 for (i = 0; i < ret; i++) 666 page_cache_get(pages[i]); 667 if (ret) 668 *index = pages[ret - 1]->index + 1; 669 read_unlock_irq(&mapping->tree_lock); 670 return ret; 671 } 672 673 /* 674 * Same as grab_cache_page, but do not wait if the page is unavailable. 675 * This is intended for speculative data generators, where the data can 676 * be regenerated if the page couldn't be grabbed. This routine should 677 * be safe to call while holding the lock for another page. 678 * 679 * Clear __GFP_FS when allocating the page to avoid recursion into the fs 680 * and deadlock against the caller's locked page. 681 */ 682 struct page * 683 grab_cache_page_nowait(struct address_space *mapping, unsigned long index) 684 { 685 struct page *page = find_get_page(mapping, index); 686 gfp_t gfp_mask; 687 688 if (page) { 689 if (!TestSetPageLocked(page)) 690 return page; 691 page_cache_release(page); 692 return NULL; 693 } 694 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS; 695 page = alloc_pages(gfp_mask, 0); 696 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) { 697 page_cache_release(page); 698 page = NULL; 699 } 700 return page; 701 } 702 703 EXPORT_SYMBOL(grab_cache_page_nowait); 704 705 /* 706 * This is a generic file read routine, and uses the 707 * mapping->a_ops->readpage() function for the actual low-level 708 * stuff. 709 * 710 * This is really ugly. But the goto's actually try to clarify some 711 * of the logic when it comes to error handling etc. 712 * 713 * Note the struct file* is only passed for the use of readpage. It may be 714 * NULL. 715 */ 716 void do_generic_mapping_read(struct address_space *mapping, 717 struct file_ra_state *_ra, 718 struct file *filp, 719 loff_t *ppos, 720 read_descriptor_t *desc, 721 read_actor_t actor) 722 { 723 struct inode *inode = mapping->host; 724 unsigned long index; 725 unsigned long end_index; 726 unsigned long offset; 727 unsigned long last_index; 728 unsigned long next_index; 729 unsigned long prev_index; 730 loff_t isize; 731 struct page *cached_page; 732 int error; 733 struct file_ra_state ra = *_ra; 734 735 cached_page = NULL; 736 index = *ppos >> PAGE_CACHE_SHIFT; 737 next_index = index; 738 prev_index = ra.prev_page; 739 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; 740 offset = *ppos & ~PAGE_CACHE_MASK; 741 742 isize = i_size_read(inode); 743 if (!isize) 744 goto out; 745 746 end_index = (isize - 1) >> PAGE_CACHE_SHIFT; 747 for (;;) { 748 struct page *page; 749 unsigned long nr, ret; 750 751 /* nr is the maximum number of bytes to copy from this page */ 752 nr = PAGE_CACHE_SIZE; 753 if (index >= end_index) { 754 if (index > end_index) 755 goto out; 756 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; 757 if (nr <= offset) { 758 goto out; 759 } 760 } 761 nr = nr - offset; 762 763 cond_resched(); 764 if (index == next_index) 765 next_index = page_cache_readahead(mapping, &ra, filp, 766 index, last_index - index); 767 768 find_page: 769 page = find_get_page(mapping, index); 770 if (unlikely(page == NULL)) { 771 handle_ra_miss(mapping, &ra, index); 772 goto no_cached_page; 773 } 774 if (!PageUptodate(page)) 775 goto page_not_up_to_date; 776 page_ok: 777 778 /* If users can be writing to this page using arbitrary 779 * virtual addresses, take care about potential aliasing 780 * before reading the page on the kernel side. 781 */ 782 if (mapping_writably_mapped(mapping)) 783 flush_dcache_page(page); 784 785 /* 786 * When (part of) the same page is read multiple times 787 * in succession, only mark it as accessed the first time. 788 */ 789 if (prev_index != index) 790 mark_page_accessed(page); 791 prev_index = index; 792 793 /* 794 * Ok, we have the page, and it's up-to-date, so 795 * now we can copy it to user space... 796 * 797 * The actor routine returns how many bytes were actually used.. 798 * NOTE! This may not be the same as how much of a user buffer 799 * we filled up (we may be padding etc), so we can only update 800 * "pos" here (the actor routine has to update the user buffer 801 * pointers and the remaining count). 802 */ 803 ret = actor(desc, page, offset, nr); 804 offset += ret; 805 index += offset >> PAGE_CACHE_SHIFT; 806 offset &= ~PAGE_CACHE_MASK; 807 808 page_cache_release(page); 809 if (ret == nr && desc->count) 810 continue; 811 goto out; 812 813 page_not_up_to_date: 814 /* Get exclusive access to the page ... */ 815 lock_page(page); 816 817 /* Did it get unhashed before we got the lock? */ 818 if (!page->mapping) { 819 unlock_page(page); 820 page_cache_release(page); 821 continue; 822 } 823 824 /* Did somebody else fill it already? */ 825 if (PageUptodate(page)) { 826 unlock_page(page); 827 goto page_ok; 828 } 829 830 readpage: 831 /* Start the actual read. The read will unlock the page. */ 832 error = mapping->a_ops->readpage(filp, page); 833 834 if (unlikely(error)) 835 goto readpage_error; 836 837 if (!PageUptodate(page)) { 838 lock_page(page); 839 if (!PageUptodate(page)) { 840 if (page->mapping == NULL) { 841 /* 842 * invalidate_inode_pages got it 843 */ 844 unlock_page(page); 845 page_cache_release(page); 846 goto find_page; 847 } 848 unlock_page(page); 849 error = -EIO; 850 goto readpage_error; 851 } 852 unlock_page(page); 853 } 854 855 /* 856 * i_size must be checked after we have done ->readpage. 857 * 858 * Checking i_size after the readpage allows us to calculate 859 * the correct value for "nr", which means the zero-filled 860 * part of the page is not copied back to userspace (unless 861 * another truncate extends the file - this is desired though). 862 */ 863 isize = i_size_read(inode); 864 end_index = (isize - 1) >> PAGE_CACHE_SHIFT; 865 if (unlikely(!isize || index > end_index)) { 866 page_cache_release(page); 867 goto out; 868 } 869 870 /* nr is the maximum number of bytes to copy from this page */ 871 nr = PAGE_CACHE_SIZE; 872 if (index == end_index) { 873 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; 874 if (nr <= offset) { 875 page_cache_release(page); 876 goto out; 877 } 878 } 879 nr = nr - offset; 880 goto page_ok; 881 882 readpage_error: 883 /* UHHUH! A synchronous read error occurred. Report it */ 884 desc->error = error; 885 page_cache_release(page); 886 goto out; 887 888 no_cached_page: 889 /* 890 * Ok, it wasn't cached, so we need to create a new 891 * page.. 892 */ 893 if (!cached_page) { 894 cached_page = page_cache_alloc_cold(mapping); 895 if (!cached_page) { 896 desc->error = -ENOMEM; 897 goto out; 898 } 899 } 900 error = add_to_page_cache_lru(cached_page, mapping, 901 index, GFP_KERNEL); 902 if (error) { 903 if (error == -EEXIST) 904 goto find_page; 905 desc->error = error; 906 goto out; 907 } 908 page = cached_page; 909 cached_page = NULL; 910 goto readpage; 911 } 912 913 out: 914 *_ra = ra; 915 916 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 917 if (cached_page) 918 page_cache_release(cached_page); 919 if (filp) 920 file_accessed(filp); 921 } 922 923 EXPORT_SYMBOL(do_generic_mapping_read); 924 925 int file_read_actor(read_descriptor_t *desc, struct page *page, 926 unsigned long offset, unsigned long size) 927 { 928 char *kaddr; 929 unsigned long left, count = desc->count; 930 931 if (size > count) 932 size = count; 933 934 /* 935 * Faults on the destination of a read are common, so do it before 936 * taking the kmap. 937 */ 938 if (!fault_in_pages_writeable(desc->arg.buf, size)) { 939 kaddr = kmap_atomic(page, KM_USER0); 940 left = __copy_to_user_inatomic(desc->arg.buf, 941 kaddr + offset, size); 942 kunmap_atomic(kaddr, KM_USER0); 943 if (left == 0) 944 goto success; 945 } 946 947 /* Do it the slow way */ 948 kaddr = kmap(page); 949 left = __copy_to_user(desc->arg.buf, kaddr + offset, size); 950 kunmap(page); 951 952 if (left) { 953 size -= left; 954 desc->error = -EFAULT; 955 } 956 success: 957 desc->count = count - size; 958 desc->written += size; 959 desc->arg.buf += size; 960 return size; 961 } 962 963 /* 964 * This is the "read()" routine for all filesystems 965 * that can use the page cache directly. 966 */ 967 ssize_t 968 __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, 969 unsigned long nr_segs, loff_t *ppos) 970 { 971 struct file *filp = iocb->ki_filp; 972 ssize_t retval; 973 unsigned long seg; 974 size_t count; 975 976 count = 0; 977 for (seg = 0; seg < nr_segs; seg++) { 978 const struct iovec *iv = &iov[seg]; 979 980 /* 981 * If any segment has a negative length, or the cumulative 982 * length ever wraps negative then return -EINVAL. 983 */ 984 count += iv->iov_len; 985 if (unlikely((ssize_t)(count|iv->iov_len) < 0)) 986 return -EINVAL; 987 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) 988 continue; 989 if (seg == 0) 990 return -EFAULT; 991 nr_segs = seg; 992 count -= iv->iov_len; /* This segment is no good */ 993 break; 994 } 995 996 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ 997 if (filp->f_flags & O_DIRECT) { 998 loff_t pos = *ppos, size; 999 struct address_space *mapping; 1000 struct inode *inode; 1001 1002 mapping = filp->f_mapping; 1003 inode = mapping->host; 1004 retval = 0; 1005 if (!count) 1006 goto out; /* skip atime */ 1007 size = i_size_read(inode); 1008 if (pos < size) { 1009 retval = generic_file_direct_IO(READ, iocb, 1010 iov, pos, nr_segs); 1011 if (retval > 0 && !is_sync_kiocb(iocb)) 1012 retval = -EIOCBQUEUED; 1013 if (retval > 0) 1014 *ppos = pos + retval; 1015 } 1016 file_accessed(filp); 1017 goto out; 1018 } 1019 1020 retval = 0; 1021 if (count) { 1022 for (seg = 0; seg < nr_segs; seg++) { 1023 read_descriptor_t desc; 1024 1025 desc.written = 0; 1026 desc.arg.buf = iov[seg].iov_base; 1027 desc.count = iov[seg].iov_len; 1028 if (desc.count == 0) 1029 continue; 1030 desc.error = 0; 1031 do_generic_file_read(filp,ppos,&desc,file_read_actor); 1032 retval += desc.written; 1033 if (desc.error) { 1034 retval = retval ?: desc.error; 1035 break; 1036 } 1037 } 1038 } 1039 out: 1040 return retval; 1041 } 1042 1043 EXPORT_SYMBOL(__generic_file_aio_read); 1044 1045 ssize_t 1046 generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) 1047 { 1048 struct iovec local_iov = { .iov_base = buf, .iov_len = count }; 1049 1050 BUG_ON(iocb->ki_pos != pos); 1051 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); 1052 } 1053 1054 EXPORT_SYMBOL(generic_file_aio_read); 1055 1056 ssize_t 1057 generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1058 { 1059 struct iovec local_iov = { .iov_base = buf, .iov_len = count }; 1060 struct kiocb kiocb; 1061 ssize_t ret; 1062 1063 init_sync_kiocb(&kiocb, filp); 1064 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); 1065 if (-EIOCBQUEUED == ret) 1066 ret = wait_on_sync_kiocb(&kiocb); 1067 return ret; 1068 } 1069 1070 EXPORT_SYMBOL(generic_file_read); 1071 1072 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) 1073 { 1074 ssize_t written; 1075 unsigned long count = desc->count; 1076 struct file *file = desc->arg.data; 1077 1078 if (size > count) 1079 size = count; 1080 1081 written = file->f_op->sendpage(file, page, offset, 1082 size, &file->f_pos, size<count); 1083 if (written < 0) { 1084 desc->error = written; 1085 written = 0; 1086 } 1087 desc->count = count - written; 1088 desc->written += written; 1089 return written; 1090 } 1091 1092 ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, 1093 size_t count, read_actor_t actor, void *target) 1094 { 1095 read_descriptor_t desc; 1096 1097 if (!count) 1098 return 0; 1099 1100 desc.written = 0; 1101 desc.count = count; 1102 desc.arg.data = target; 1103 desc.error = 0; 1104 1105 do_generic_file_read(in_file, ppos, &desc, actor); 1106 if (desc.written) 1107 return desc.written; 1108 return desc.error; 1109 } 1110 1111 EXPORT_SYMBOL(generic_file_sendfile); 1112 1113 static ssize_t 1114 do_readahead(struct address_space *mapping, struct file *filp, 1115 unsigned long index, unsigned long nr) 1116 { 1117 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) 1118 return -EINVAL; 1119 1120 force_page_cache_readahead(mapping, filp, index, 1121 max_sane_readahead(nr)); 1122 return 0; 1123 } 1124 1125 asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) 1126 { 1127 ssize_t ret; 1128 struct file *file; 1129 1130 ret = -EBADF; 1131 file = fget(fd); 1132 if (file) { 1133 if (file->f_mode & FMODE_READ) { 1134 struct address_space *mapping = file->f_mapping; 1135 unsigned long start = offset >> PAGE_CACHE_SHIFT; 1136 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT; 1137 unsigned long len = end - start + 1; 1138 ret = do_readahead(mapping, file, start, len); 1139 } 1140 fput(file); 1141 } 1142 return ret; 1143 } 1144 1145 #ifdef CONFIG_MMU 1146 /* 1147 * This adds the requested page to the page cache if it isn't already there, 1148 * and schedules an I/O to read in its contents from disk. 1149 */ 1150 static int FASTCALL(page_cache_read(struct file * file, unsigned long offset)); 1151 static int fastcall page_cache_read(struct file * file, unsigned long offset) 1152 { 1153 struct address_space *mapping = file->f_mapping; 1154 struct page *page; 1155 int error; 1156 1157 page = page_cache_alloc_cold(mapping); 1158 if (!page) 1159 return -ENOMEM; 1160 1161 error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); 1162 if (!error) { 1163 error = mapping->a_ops->readpage(file, page); 1164 page_cache_release(page); 1165 return error; 1166 } 1167 1168 /* 1169 * We arrive here in the unlikely event that someone 1170 * raced with us and added our page to the cache first 1171 * or we are out of memory for radix-tree nodes. 1172 */ 1173 page_cache_release(page); 1174 return error == -EEXIST ? 0 : error; 1175 } 1176 1177 #define MMAP_LOTSAMISS (100) 1178 1179 /* 1180 * filemap_nopage() is invoked via the vma operations vector for a 1181 * mapped memory region to read in file data during a page fault. 1182 * 1183 * The goto's are kind of ugly, but this streamlines the normal case of having 1184 * it in the page cache, and handles the special cases reasonably without 1185 * having a lot of duplicated code. 1186 */ 1187 struct page *filemap_nopage(struct vm_area_struct *area, 1188 unsigned long address, int *type) 1189 { 1190 int error; 1191 struct file *file = area->vm_file; 1192 struct address_space *mapping = file->f_mapping; 1193 struct file_ra_state *ra = &file->f_ra; 1194 struct inode *inode = mapping->host; 1195 struct page *page; 1196 unsigned long size, pgoff; 1197 int did_readaround = 0, majmin = VM_FAULT_MINOR; 1198 1199 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; 1200 1201 retry_all: 1202 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 1203 if (pgoff >= size) 1204 goto outside_data_content; 1205 1206 /* If we don't want any read-ahead, don't bother */ 1207 if (VM_RandomReadHint(area)) 1208 goto no_cached_page; 1209 1210 /* 1211 * The readahead code wants to be told about each and every page 1212 * so it can build and shrink its windows appropriately 1213 * 1214 * For sequential accesses, we use the generic readahead logic. 1215 */ 1216 if (VM_SequentialReadHint(area)) 1217 page_cache_readahead(mapping, ra, file, pgoff, 1); 1218 1219 /* 1220 * Do we have something in the page cache already? 1221 */ 1222 retry_find: 1223 page = find_get_page(mapping, pgoff); 1224 if (!page) { 1225 unsigned long ra_pages; 1226 1227 if (VM_SequentialReadHint(area)) { 1228 handle_ra_miss(mapping, ra, pgoff); 1229 goto no_cached_page; 1230 } 1231 ra->mmap_miss++; 1232 1233 /* 1234 * Do we miss much more than hit in this file? If so, 1235 * stop bothering with read-ahead. It will only hurt. 1236 */ 1237 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS) 1238 goto no_cached_page; 1239 1240 /* 1241 * To keep the pgmajfault counter straight, we need to 1242 * check did_readaround, as this is an inner loop. 1243 */ 1244 if (!did_readaround) { 1245 majmin = VM_FAULT_MAJOR; 1246 inc_page_state(pgmajfault); 1247 } 1248 did_readaround = 1; 1249 ra_pages = max_sane_readahead(file->f_ra.ra_pages); 1250 if (ra_pages) { 1251 pgoff_t start = 0; 1252 1253 if (pgoff > ra_pages / 2) 1254 start = pgoff - ra_pages / 2; 1255 do_page_cache_readahead(mapping, file, start, ra_pages); 1256 } 1257 page = find_get_page(mapping, pgoff); 1258 if (!page) 1259 goto no_cached_page; 1260 } 1261 1262 if (!did_readaround) 1263 ra->mmap_hit++; 1264 1265 /* 1266 * Ok, found a page in the page cache, now we need to check 1267 * that it's up-to-date. 1268 */ 1269 if (!PageUptodate(page)) 1270 goto page_not_uptodate; 1271 1272 success: 1273 /* 1274 * Found the page and have a reference on it. 1275 */ 1276 mark_page_accessed(page); 1277 if (type) 1278 *type = majmin; 1279 return page; 1280 1281 outside_data_content: 1282 /* 1283 * An external ptracer can access pages that normally aren't 1284 * accessible.. 1285 */ 1286 if (area->vm_mm == current->mm) 1287 return NULL; 1288 /* Fall through to the non-read-ahead case */ 1289 no_cached_page: 1290 /* 1291 * We're only likely to ever get here if MADV_RANDOM is in 1292 * effect. 1293 */ 1294 error = page_cache_read(file, pgoff); 1295 grab_swap_token(); 1296 1297 /* 1298 * The page we want has now been added to the page cache. 1299 * In the unlikely event that someone removed it in the 1300 * meantime, we'll just come back here and read it again. 1301 */ 1302 if (error >= 0) 1303 goto retry_find; 1304 1305 /* 1306 * An error return from page_cache_read can result if the 1307 * system is low on memory, or a problem occurs while trying 1308 * to schedule I/O. 1309 */ 1310 if (error == -ENOMEM) 1311 return NOPAGE_OOM; 1312 return NULL; 1313 1314 page_not_uptodate: 1315 if (!did_readaround) { 1316 majmin = VM_FAULT_MAJOR; 1317 inc_page_state(pgmajfault); 1318 } 1319 lock_page(page); 1320 1321 /* Did it get unhashed while we waited for it? */ 1322 if (!page->mapping) { 1323 unlock_page(page); 1324 page_cache_release(page); 1325 goto retry_all; 1326 } 1327 1328 /* Did somebody else get it up-to-date? */ 1329 if (PageUptodate(page)) { 1330 unlock_page(page); 1331 goto success; 1332 } 1333 1334 if (!mapping->a_ops->readpage(file, page)) { 1335 wait_on_page_locked(page); 1336 if (PageUptodate(page)) 1337 goto success; 1338 } 1339 1340 /* 1341 * Umm, take care of errors if the page isn't up-to-date. 1342 * Try to re-read it _once_. We do this synchronously, 1343 * because there really aren't any performance issues here 1344 * and we need to check for errors. 1345 */ 1346 lock_page(page); 1347 1348 /* Somebody truncated the page on us? */ 1349 if (!page->mapping) { 1350 unlock_page(page); 1351 page_cache_release(page); 1352 goto retry_all; 1353 } 1354 1355 /* Somebody else successfully read it in? */ 1356 if (PageUptodate(page)) { 1357 unlock_page(page); 1358 goto success; 1359 } 1360 ClearPageError(page); 1361 if (!mapping->a_ops->readpage(file, page)) { 1362 wait_on_page_locked(page); 1363 if (PageUptodate(page)) 1364 goto success; 1365 } 1366 1367 /* 1368 * Things didn't work out. Return zero to tell the 1369 * mm layer so, possibly freeing the page cache page first. 1370 */ 1371 page_cache_release(page); 1372 return NULL; 1373 } 1374 1375 EXPORT_SYMBOL(filemap_nopage); 1376 1377 static struct page * filemap_getpage(struct file *file, unsigned long pgoff, 1378 int nonblock) 1379 { 1380 struct address_space *mapping = file->f_mapping; 1381 struct page *page; 1382 int error; 1383 1384 /* 1385 * Do we have something in the page cache already? 1386 */ 1387 retry_find: 1388 page = find_get_page(mapping, pgoff); 1389 if (!page) { 1390 if (nonblock) 1391 return NULL; 1392 goto no_cached_page; 1393 } 1394 1395 /* 1396 * Ok, found a page in the page cache, now we need to check 1397 * that it's up-to-date. 1398 */ 1399 if (!PageUptodate(page)) { 1400 if (nonblock) { 1401 page_cache_release(page); 1402 return NULL; 1403 } 1404 goto page_not_uptodate; 1405 } 1406 1407 success: 1408 /* 1409 * Found the page and have a reference on it. 1410 */ 1411 mark_page_accessed(page); 1412 return page; 1413 1414 no_cached_page: 1415 error = page_cache_read(file, pgoff); 1416 1417 /* 1418 * The page we want has now been added to the page cache. 1419 * In the unlikely event that someone removed it in the 1420 * meantime, we'll just come back here and read it again. 1421 */ 1422 if (error >= 0) 1423 goto retry_find; 1424 1425 /* 1426 * An error return from page_cache_read can result if the 1427 * system is low on memory, or a problem occurs while trying 1428 * to schedule I/O. 1429 */ 1430 return NULL; 1431 1432 page_not_uptodate: 1433 lock_page(page); 1434 1435 /* Did it get unhashed while we waited for it? */ 1436 if (!page->mapping) { 1437 unlock_page(page); 1438 goto err; 1439 } 1440 1441 /* Did somebody else get it up-to-date? */ 1442 if (PageUptodate(page)) { 1443 unlock_page(page); 1444 goto success; 1445 } 1446 1447 if (!mapping->a_ops->readpage(file, page)) { 1448 wait_on_page_locked(page); 1449 if (PageUptodate(page)) 1450 goto success; 1451 } 1452 1453 /* 1454 * Umm, take care of errors if the page isn't up-to-date. 1455 * Try to re-read it _once_. We do this synchronously, 1456 * because there really aren't any performance issues here 1457 * and we need to check for errors. 1458 */ 1459 lock_page(page); 1460 1461 /* Somebody truncated the page on us? */ 1462 if (!page->mapping) { 1463 unlock_page(page); 1464 goto err; 1465 } 1466 /* Somebody else successfully read it in? */ 1467 if (PageUptodate(page)) { 1468 unlock_page(page); 1469 goto success; 1470 } 1471 1472 ClearPageError(page); 1473 if (!mapping->a_ops->readpage(file, page)) { 1474 wait_on_page_locked(page); 1475 if (PageUptodate(page)) 1476 goto success; 1477 } 1478 1479 /* 1480 * Things didn't work out. Return zero to tell the 1481 * mm layer so, possibly freeing the page cache page first. 1482 */ 1483 err: 1484 page_cache_release(page); 1485 1486 return NULL; 1487 } 1488 1489 int filemap_populate(struct vm_area_struct *vma, unsigned long addr, 1490 unsigned long len, pgprot_t prot, unsigned long pgoff, 1491 int nonblock) 1492 { 1493 struct file *file = vma->vm_file; 1494 struct address_space *mapping = file->f_mapping; 1495 struct inode *inode = mapping->host; 1496 unsigned long size; 1497 struct mm_struct *mm = vma->vm_mm; 1498 struct page *page; 1499 int err; 1500 1501 if (!nonblock) 1502 force_page_cache_readahead(mapping, vma->vm_file, 1503 pgoff, len >> PAGE_CACHE_SHIFT); 1504 1505 repeat: 1506 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 1507 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) 1508 return -EINVAL; 1509 1510 page = filemap_getpage(file, pgoff, nonblock); 1511 1512 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as 1513 * done in shmem_populate calling shmem_getpage */ 1514 if (!page && !nonblock) 1515 return -ENOMEM; 1516 1517 if (page) { 1518 err = install_page(mm, vma, addr, page, prot); 1519 if (err) { 1520 page_cache_release(page); 1521 return err; 1522 } 1523 } else if (vma->vm_flags & VM_NONLINEAR) { 1524 /* No page was found just because we can't read it in now (being 1525 * here implies nonblock != 0), but the page may exist, so set 1526 * the PTE to fault it in later. */ 1527 err = install_file_pte(mm, vma, addr, pgoff, prot); 1528 if (err) 1529 return err; 1530 } 1531 1532 len -= PAGE_SIZE; 1533 addr += PAGE_SIZE; 1534 pgoff++; 1535 if (len) 1536 goto repeat; 1537 1538 return 0; 1539 } 1540 EXPORT_SYMBOL(filemap_populate); 1541 1542 struct vm_operations_struct generic_file_vm_ops = { 1543 .nopage = filemap_nopage, 1544 .populate = filemap_populate, 1545 }; 1546 1547 /* This is used for a general mmap of a disk file */ 1548 1549 int generic_file_mmap(struct file * file, struct vm_area_struct * vma) 1550 { 1551 struct address_space *mapping = file->f_mapping; 1552 1553 if (!mapping->a_ops->readpage) 1554 return -ENOEXEC; 1555 file_accessed(file); 1556 vma->vm_ops = &generic_file_vm_ops; 1557 return 0; 1558 } 1559 1560 /* 1561 * This is for filesystems which do not implement ->writepage. 1562 */ 1563 int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) 1564 { 1565 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) 1566 return -EINVAL; 1567 return generic_file_mmap(file, vma); 1568 } 1569 #else 1570 int generic_file_mmap(struct file * file, struct vm_area_struct * vma) 1571 { 1572 return -ENOSYS; 1573 } 1574 int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) 1575 { 1576 return -ENOSYS; 1577 } 1578 #endif /* CONFIG_MMU */ 1579 1580 EXPORT_SYMBOL(generic_file_mmap); 1581 EXPORT_SYMBOL(generic_file_readonly_mmap); 1582 1583 static inline struct page *__read_cache_page(struct address_space *mapping, 1584 unsigned long index, 1585 int (*filler)(void *,struct page*), 1586 void *data) 1587 { 1588 struct page *page, *cached_page = NULL; 1589 int err; 1590 repeat: 1591 page = find_get_page(mapping, index); 1592 if (!page) { 1593 if (!cached_page) { 1594 cached_page = page_cache_alloc_cold(mapping); 1595 if (!cached_page) 1596 return ERR_PTR(-ENOMEM); 1597 } 1598 err = add_to_page_cache_lru(cached_page, mapping, 1599 index, GFP_KERNEL); 1600 if (err == -EEXIST) 1601 goto repeat; 1602 if (err < 0) { 1603 /* Presumably ENOMEM for radix tree node */ 1604 page_cache_release(cached_page); 1605 return ERR_PTR(err); 1606 } 1607 page = cached_page; 1608 cached_page = NULL; 1609 err = filler(data, page); 1610 if (err < 0) { 1611 page_cache_release(page); 1612 page = ERR_PTR(err); 1613 } 1614 } 1615 if (cached_page) 1616 page_cache_release(cached_page); 1617 return page; 1618 } 1619 1620 /* 1621 * Read into the page cache. If a page already exists, 1622 * and PageUptodate() is not set, try to fill the page. 1623 */ 1624 struct page *read_cache_page(struct address_space *mapping, 1625 unsigned long index, 1626 int (*filler)(void *,struct page*), 1627 void *data) 1628 { 1629 struct page *page; 1630 int err; 1631 1632 retry: 1633 page = __read_cache_page(mapping, index, filler, data); 1634 if (IS_ERR(page)) 1635 goto out; 1636 mark_page_accessed(page); 1637 if (PageUptodate(page)) 1638 goto out; 1639 1640 lock_page(page); 1641 if (!page->mapping) { 1642 unlock_page(page); 1643 page_cache_release(page); 1644 goto retry; 1645 } 1646 if (PageUptodate(page)) { 1647 unlock_page(page); 1648 goto out; 1649 } 1650 err = filler(data, page); 1651 if (err < 0) { 1652 page_cache_release(page); 1653 page = ERR_PTR(err); 1654 } 1655 out: 1656 return page; 1657 } 1658 1659 EXPORT_SYMBOL(read_cache_page); 1660 1661 /* 1662 * If the page was newly created, increment its refcount and add it to the 1663 * caller's lru-buffering pagevec. This function is specifically for 1664 * generic_file_write(). 1665 */ 1666 static inline struct page * 1667 __grab_cache_page(struct address_space *mapping, unsigned long index, 1668 struct page **cached_page, struct pagevec *lru_pvec) 1669 { 1670 int err; 1671 struct page *page; 1672 repeat: 1673 page = find_lock_page(mapping, index); 1674 if (!page) { 1675 if (!*cached_page) { 1676 *cached_page = page_cache_alloc(mapping); 1677 if (!*cached_page) 1678 return NULL; 1679 } 1680 err = add_to_page_cache(*cached_page, mapping, 1681 index, GFP_KERNEL); 1682 if (err == -EEXIST) 1683 goto repeat; 1684 if (err == 0) { 1685 page = *cached_page; 1686 page_cache_get(page); 1687 if (!pagevec_add(lru_pvec, page)) 1688 __pagevec_lru_add(lru_pvec); 1689 *cached_page = NULL; 1690 } 1691 } 1692 return page; 1693 } 1694 1695 /* 1696 * The logic we want is 1697 * 1698 * if suid or (sgid and xgrp) 1699 * remove privs 1700 */ 1701 int remove_suid(struct dentry *dentry) 1702 { 1703 mode_t mode = dentry->d_inode->i_mode; 1704 int kill = 0; 1705 int result = 0; 1706 1707 /* suid always must be killed */ 1708 if (unlikely(mode & S_ISUID)) 1709 kill = ATTR_KILL_SUID; 1710 1711 /* 1712 * sgid without any exec bits is just a mandatory locking mark; leave 1713 * it alone. If some exec bits are set, it's a real sgid; kill it. 1714 */ 1715 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) 1716 kill |= ATTR_KILL_SGID; 1717 1718 if (unlikely(kill && !capable(CAP_FSETID))) { 1719 struct iattr newattrs; 1720 1721 newattrs.ia_valid = ATTR_FORCE | kill; 1722 result = notify_change(dentry, &newattrs); 1723 } 1724 return result; 1725 } 1726 EXPORT_SYMBOL(remove_suid); 1727 1728 size_t 1729 __filemap_copy_from_user_iovec(char *vaddr, 1730 const struct iovec *iov, size_t base, size_t bytes) 1731 { 1732 size_t copied = 0, left = 0; 1733 1734 while (bytes) { 1735 char __user *buf = iov->iov_base + base; 1736 int copy = min(bytes, iov->iov_len - base); 1737 1738 base = 0; 1739 left = __copy_from_user_inatomic(vaddr, buf, copy); 1740 copied += copy; 1741 bytes -= copy; 1742 vaddr += copy; 1743 iov++; 1744 1745 if (unlikely(left)) { 1746 /* zero the rest of the target like __copy_from_user */ 1747 if (bytes) 1748 memset(vaddr, 0, bytes); 1749 break; 1750 } 1751 } 1752 return copied - left; 1753 } 1754 1755 /* 1756 * Performs necessary checks before doing a write 1757 * 1758 * Can adjust writing position aor amount of bytes to write. 1759 * Returns appropriate error code that caller should return or 1760 * zero in case that write should be allowed. 1761 */ 1762 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) 1763 { 1764 struct inode *inode = file->f_mapping->host; 1765 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1766 1767 if (unlikely(*pos < 0)) 1768 return -EINVAL; 1769 1770 if (!isblk) { 1771 /* FIXME: this is for backwards compatibility with 2.4 */ 1772 if (file->f_flags & O_APPEND) 1773 *pos = i_size_read(inode); 1774 1775 if (limit != RLIM_INFINITY) { 1776 if (*pos >= limit) { 1777 send_sig(SIGXFSZ, current, 0); 1778 return -EFBIG; 1779 } 1780 if (*count > limit - (typeof(limit))*pos) { 1781 *count = limit - (typeof(limit))*pos; 1782 } 1783 } 1784 } 1785 1786 /* 1787 * LFS rule 1788 */ 1789 if (unlikely(*pos + *count > MAX_NON_LFS && 1790 !(file->f_flags & O_LARGEFILE))) { 1791 if (*pos >= MAX_NON_LFS) { 1792 send_sig(SIGXFSZ, current, 0); 1793 return -EFBIG; 1794 } 1795 if (*count > MAX_NON_LFS - (unsigned long)*pos) { 1796 *count = MAX_NON_LFS - (unsigned long)*pos; 1797 } 1798 } 1799 1800 /* 1801 * Are we about to exceed the fs block limit ? 1802 * 1803 * If we have written data it becomes a short write. If we have 1804 * exceeded without writing data we send a signal and return EFBIG. 1805 * Linus frestrict idea will clean these up nicely.. 1806 */ 1807 if (likely(!isblk)) { 1808 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { 1809 if (*count || *pos > inode->i_sb->s_maxbytes) { 1810 send_sig(SIGXFSZ, current, 0); 1811 return -EFBIG; 1812 } 1813 /* zero-length writes at ->s_maxbytes are OK */ 1814 } 1815 1816 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) 1817 *count = inode->i_sb->s_maxbytes - *pos; 1818 } else { 1819 loff_t isize; 1820 if (bdev_read_only(I_BDEV(inode))) 1821 return -EPERM; 1822 isize = i_size_read(inode); 1823 if (*pos >= isize) { 1824 if (*count || *pos > isize) 1825 return -ENOSPC; 1826 } 1827 1828 if (*pos + *count > isize) 1829 *count = isize - *pos; 1830 } 1831 return 0; 1832 } 1833 EXPORT_SYMBOL(generic_write_checks); 1834 1835 ssize_t 1836 generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, 1837 unsigned long *nr_segs, loff_t pos, loff_t *ppos, 1838 size_t count, size_t ocount) 1839 { 1840 struct file *file = iocb->ki_filp; 1841 struct address_space *mapping = file->f_mapping; 1842 struct inode *inode = mapping->host; 1843 ssize_t written; 1844 1845 if (count != ocount) 1846 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); 1847 1848 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); 1849 if (written > 0) { 1850 loff_t end = pos + written; 1851 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { 1852 i_size_write(inode, end); 1853 mark_inode_dirty(inode); 1854 } 1855 *ppos = end; 1856 } 1857 1858 /* 1859 * Sync the fs metadata but not the minor inode changes and 1860 * of course not the data as we did direct DMA for the IO. 1861 * i_sem is held, which protects generic_osync_inode() from 1862 * livelocking. 1863 */ 1864 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 1865 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); 1866 if (err < 0) 1867 written = err; 1868 } 1869 if (written == count && !is_sync_kiocb(iocb)) 1870 written = -EIOCBQUEUED; 1871 return written; 1872 } 1873 EXPORT_SYMBOL(generic_file_direct_write); 1874 1875 ssize_t 1876 generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, 1877 unsigned long nr_segs, loff_t pos, loff_t *ppos, 1878 size_t count, ssize_t written) 1879 { 1880 struct file *file = iocb->ki_filp; 1881 struct address_space * mapping = file->f_mapping; 1882 struct address_space_operations *a_ops = mapping->a_ops; 1883 struct inode *inode = mapping->host; 1884 long status = 0; 1885 struct page *page; 1886 struct page *cached_page = NULL; 1887 size_t bytes; 1888 struct pagevec lru_pvec; 1889 const struct iovec *cur_iov = iov; /* current iovec */ 1890 size_t iov_base = 0; /* offset in the current iovec */ 1891 char __user *buf; 1892 1893 pagevec_init(&lru_pvec, 0); 1894 1895 /* 1896 * handle partial DIO write. Adjust cur_iov if needed. 1897 */ 1898 if (likely(nr_segs == 1)) 1899 buf = iov->iov_base + written; 1900 else { 1901 filemap_set_next_iovec(&cur_iov, &iov_base, written); 1902 buf = cur_iov->iov_base + iov_base; 1903 } 1904 1905 do { 1906 unsigned long index; 1907 unsigned long offset; 1908 unsigned long maxlen; 1909 size_t copied; 1910 1911 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1912 index = pos >> PAGE_CACHE_SHIFT; 1913 bytes = PAGE_CACHE_SIZE - offset; 1914 if (bytes > count) 1915 bytes = count; 1916 1917 /* 1918 * Bring in the user page that we will copy from _first_. 1919 * Otherwise there's a nasty deadlock on copying from the 1920 * same page as we're writing to, without it being marked 1921 * up-to-date. 1922 */ 1923 maxlen = cur_iov->iov_len - iov_base; 1924 if (maxlen > bytes) 1925 maxlen = bytes; 1926 fault_in_pages_readable(buf, maxlen); 1927 1928 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); 1929 if (!page) { 1930 status = -ENOMEM; 1931 break; 1932 } 1933 1934 status = a_ops->prepare_write(file, page, offset, offset+bytes); 1935 if (unlikely(status)) { 1936 loff_t isize = i_size_read(inode); 1937 /* 1938 * prepare_write() may have instantiated a few blocks 1939 * outside i_size. Trim these off again. 1940 */ 1941 unlock_page(page); 1942 page_cache_release(page); 1943 if (pos + bytes > isize) 1944 vmtruncate(inode, isize); 1945 break; 1946 } 1947 if (likely(nr_segs == 1)) 1948 copied = filemap_copy_from_user(page, offset, 1949 buf, bytes); 1950 else 1951 copied = filemap_copy_from_user_iovec(page, offset, 1952 cur_iov, iov_base, bytes); 1953 flush_dcache_page(page); 1954 status = a_ops->commit_write(file, page, offset, offset+bytes); 1955 if (likely(copied > 0)) { 1956 if (!status) 1957 status = copied; 1958 1959 if (status >= 0) { 1960 written += status; 1961 count -= status; 1962 pos += status; 1963 buf += status; 1964 if (unlikely(nr_segs > 1)) { 1965 filemap_set_next_iovec(&cur_iov, 1966 &iov_base, status); 1967 if (count) 1968 buf = cur_iov->iov_base + 1969 iov_base; 1970 } else { 1971 iov_base += status; 1972 } 1973 } 1974 } 1975 if (unlikely(copied != bytes)) 1976 if (status >= 0) 1977 status = -EFAULT; 1978 unlock_page(page); 1979 mark_page_accessed(page); 1980 page_cache_release(page); 1981 if (status < 0) 1982 break; 1983 balance_dirty_pages_ratelimited(mapping); 1984 cond_resched(); 1985 } while (count); 1986 *ppos = pos; 1987 1988 if (cached_page) 1989 page_cache_release(cached_page); 1990 1991 /* 1992 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC 1993 */ 1994 if (likely(status >= 0)) { 1995 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 1996 if (!a_ops->writepage || !is_sync_kiocb(iocb)) 1997 status = generic_osync_inode(inode, mapping, 1998 OSYNC_METADATA|OSYNC_DATA); 1999 } 2000 } 2001 2002 /* 2003 * If we get here for O_DIRECT writes then we must have fallen through 2004 * to buffered writes (block instantiation inside i_size). So we sync 2005 * the file data here, to try to honour O_DIRECT expectations. 2006 */ 2007 if (unlikely(file->f_flags & O_DIRECT) && written) 2008 status = filemap_write_and_wait(mapping); 2009 2010 pagevec_lru_add(&lru_pvec); 2011 return written ? written : status; 2012 } 2013 EXPORT_SYMBOL(generic_file_buffered_write); 2014 2015 static ssize_t 2016 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, 2017 unsigned long nr_segs, loff_t *ppos) 2018 { 2019 struct file *file = iocb->ki_filp; 2020 struct address_space * mapping = file->f_mapping; 2021 size_t ocount; /* original count */ 2022 size_t count; /* after file limit checks */ 2023 struct inode *inode = mapping->host; 2024 unsigned long seg; 2025 loff_t pos; 2026 ssize_t written; 2027 ssize_t err; 2028 2029 ocount = 0; 2030 for (seg = 0; seg < nr_segs; seg++) { 2031 const struct iovec *iv = &iov[seg]; 2032 2033 /* 2034 * If any segment has a negative length, or the cumulative 2035 * length ever wraps negative then return -EINVAL. 2036 */ 2037 ocount += iv->iov_len; 2038 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) 2039 return -EINVAL; 2040 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) 2041 continue; 2042 if (seg == 0) 2043 return -EFAULT; 2044 nr_segs = seg; 2045 ocount -= iv->iov_len; /* This segment is no good */ 2046 break; 2047 } 2048 2049 count = ocount; 2050 pos = *ppos; 2051 2052 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); 2053 2054 /* We can write back this queue in page reclaim */ 2055 current->backing_dev_info = mapping->backing_dev_info; 2056 written = 0; 2057 2058 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); 2059 if (err) 2060 goto out; 2061 2062 if (count == 0) 2063 goto out; 2064 2065 err = remove_suid(file->f_dentry); 2066 if (err) 2067 goto out; 2068 2069 inode_update_time(inode, 1); 2070 2071 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ 2072 if (unlikely(file->f_flags & O_DIRECT)) { 2073 written = generic_file_direct_write(iocb, iov, 2074 &nr_segs, pos, ppos, count, ocount); 2075 if (written < 0 || written == count) 2076 goto out; 2077 /* 2078 * direct-io write to a hole: fall through to buffered I/O 2079 * for completing the rest of the request. 2080 */ 2081 pos += written; 2082 count -= written; 2083 } 2084 2085 written = generic_file_buffered_write(iocb, iov, nr_segs, 2086 pos, ppos, count, written); 2087 out: 2088 current->backing_dev_info = NULL; 2089 return written ? written : err; 2090 } 2091 EXPORT_SYMBOL(generic_file_aio_write_nolock); 2092 2093 ssize_t 2094 generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, 2095 unsigned long nr_segs, loff_t *ppos) 2096 { 2097 struct file *file = iocb->ki_filp; 2098 struct address_space *mapping = file->f_mapping; 2099 struct inode *inode = mapping->host; 2100 ssize_t ret; 2101 loff_t pos = *ppos; 2102 2103 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos); 2104 2105 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2106 int err; 2107 2108 err = sync_page_range_nolock(inode, mapping, pos, ret); 2109 if (err < 0) 2110 ret = err; 2111 } 2112 return ret; 2113 } 2114 2115 static ssize_t 2116 __generic_file_write_nolock(struct file *file, const struct iovec *iov, 2117 unsigned long nr_segs, loff_t *ppos) 2118 { 2119 struct kiocb kiocb; 2120 ssize_t ret; 2121 2122 init_sync_kiocb(&kiocb, file); 2123 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); 2124 if (ret == -EIOCBQUEUED) 2125 ret = wait_on_sync_kiocb(&kiocb); 2126 return ret; 2127 } 2128 2129 ssize_t 2130 generic_file_write_nolock(struct file *file, const struct iovec *iov, 2131 unsigned long nr_segs, loff_t *ppos) 2132 { 2133 struct kiocb kiocb; 2134 ssize_t ret; 2135 2136 init_sync_kiocb(&kiocb, file); 2137 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); 2138 if (-EIOCBQUEUED == ret) 2139 ret = wait_on_sync_kiocb(&kiocb); 2140 return ret; 2141 } 2142 EXPORT_SYMBOL(generic_file_write_nolock); 2143 2144 ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf, 2145 size_t count, loff_t pos) 2146 { 2147 struct file *file = iocb->ki_filp; 2148 struct address_space *mapping = file->f_mapping; 2149 struct inode *inode = mapping->host; 2150 ssize_t ret; 2151 struct iovec local_iov = { .iov_base = (void __user *)buf, 2152 .iov_len = count }; 2153 2154 BUG_ON(iocb->ki_pos != pos); 2155 2156 down(&inode->i_sem); 2157 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1, 2158 &iocb->ki_pos); 2159 up(&inode->i_sem); 2160 2161 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2162 ssize_t err; 2163 2164 err = sync_page_range(inode, mapping, pos, ret); 2165 if (err < 0) 2166 ret = err; 2167 } 2168 return ret; 2169 } 2170 EXPORT_SYMBOL(generic_file_aio_write); 2171 2172 ssize_t generic_file_write(struct file *file, const char __user *buf, 2173 size_t count, loff_t *ppos) 2174 { 2175 struct address_space *mapping = file->f_mapping; 2176 struct inode *inode = mapping->host; 2177 ssize_t ret; 2178 struct iovec local_iov = { .iov_base = (void __user *)buf, 2179 .iov_len = count }; 2180 2181 down(&inode->i_sem); 2182 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos); 2183 up(&inode->i_sem); 2184 2185 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2186 ssize_t err; 2187 2188 err = sync_page_range(inode, mapping, *ppos - ret, ret); 2189 if (err < 0) 2190 ret = err; 2191 } 2192 return ret; 2193 } 2194 EXPORT_SYMBOL(generic_file_write); 2195 2196 ssize_t generic_file_readv(struct file *filp, const struct iovec *iov, 2197 unsigned long nr_segs, loff_t *ppos) 2198 { 2199 struct kiocb kiocb; 2200 ssize_t ret; 2201 2202 init_sync_kiocb(&kiocb, filp); 2203 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos); 2204 if (-EIOCBQUEUED == ret) 2205 ret = wait_on_sync_kiocb(&kiocb); 2206 return ret; 2207 } 2208 EXPORT_SYMBOL(generic_file_readv); 2209 2210 ssize_t generic_file_writev(struct file *file, const struct iovec *iov, 2211 unsigned long nr_segs, loff_t *ppos) 2212 { 2213 struct address_space *mapping = file->f_mapping; 2214 struct inode *inode = mapping->host; 2215 ssize_t ret; 2216 2217 down(&inode->i_sem); 2218 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos); 2219 up(&inode->i_sem); 2220 2221 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2222 int err; 2223 2224 err = sync_page_range(inode, mapping, *ppos - ret, ret); 2225 if (err < 0) 2226 ret = err; 2227 } 2228 return ret; 2229 } 2230 EXPORT_SYMBOL(generic_file_writev); 2231 2232 /* 2233 * Called under i_sem for writes to S_ISREG files. Returns -EIO if something 2234 * went wrong during pagecache shootdown. 2235 */ 2236 static ssize_t 2237 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, 2238 loff_t offset, unsigned long nr_segs) 2239 { 2240 struct file *file = iocb->ki_filp; 2241 struct address_space *mapping = file->f_mapping; 2242 ssize_t retval; 2243 size_t write_len = 0; 2244 2245 /* 2246 * If it's a write, unmap all mmappings of the file up-front. This 2247 * will cause any pte dirty bits to be propagated into the pageframes 2248 * for the subsequent filemap_write_and_wait(). 2249 */ 2250 if (rw == WRITE) { 2251 write_len = iov_length(iov, nr_segs); 2252 if (mapping_mapped(mapping)) 2253 unmap_mapping_range(mapping, offset, write_len, 0); 2254 } 2255 2256 retval = filemap_write_and_wait(mapping); 2257 if (retval == 0) { 2258 retval = mapping->a_ops->direct_IO(rw, iocb, iov, 2259 offset, nr_segs); 2260 if (rw == WRITE && mapping->nrpages) { 2261 pgoff_t end = (offset + write_len - 1) 2262 >> PAGE_CACHE_SHIFT; 2263 int err = invalidate_inode_pages2_range(mapping, 2264 offset >> PAGE_CACHE_SHIFT, end); 2265 if (err) 2266 retval = err; 2267 } 2268 } 2269 return retval; 2270 } 2271