filemap.c revision d345734267dbec642f4e34a9d392d2fd85b5fa9b
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/* 32 * This is needed for the following functions: 33 * - try_to_release_page 34 * - block_invalidatepage 35 * - generic_osync_inode 36 * 37 * FIXME: remove all knowledge of the buffer layer from the core VM 38 */ 39#include <linux/buffer_head.h> /* for generic_osync_inode */ 40 41#include <asm/uaccess.h> 42#include <asm/mman.h> 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_list_lock 62 * ->swap_device_lock (exclusive_swap_page, others) 63 * ->mapping->tree_lock 64 * 65 * ->i_sem 66 * ->i_mmap_lock (truncate->unmap_mapping_range) 67 * 68 * ->mmap_sem 69 * ->i_mmap_lock 70 * ->page_table_lock (various places, mainly in mmap.c) 71 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) 72 * 73 * ->mmap_sem 74 * ->lock_page (access_process_vm) 75 * 76 * ->mmap_sem 77 * ->i_sem (msync) 78 * 79 * ->i_sem 80 * ->i_alloc_sem (various) 81 * 82 * ->inode_lock 83 * ->sb_lock (fs/fs-writeback.c) 84 * ->mapping->tree_lock (__sync_single_inode) 85 * 86 * ->i_mmap_lock 87 * ->anon_vma.lock (vma_adjust) 88 * 89 * ->anon_vma.lock 90 * ->page_table_lock (anon_vma_prepare and various) 91 * 92 * ->page_table_lock 93 * ->swap_device_lock (try_to_unmap_one) 94 * ->private_lock (try_to_unmap_one) 95 * ->tree_lock (try_to_unmap_one) 96 * ->zone.lru_lock (follow_page->mark_page_accessed) 97 * ->private_lock (page_remove_rmap->set_page_dirty) 98 * ->tree_lock (page_remove_rmap->set_page_dirty) 99 * ->inode_lock (page_remove_rmap->set_page_dirty) 100 * ->inode_lock (zap_pte_range->set_page_dirty) 101 * ->private_lock (zap_pte_range->__set_page_dirty_buffers) 102 * 103 * ->task->proc_lock 104 * ->dcache_lock (proc_pid_lookup) 105 */ 106 107/* 108 * Remove a page from the page cache and free it. Caller has to make 109 * sure the page is locked and that nobody else uses it - or that usage 110 * is safe. The caller must hold a write_lock on the mapping's tree_lock. 111 */ 112void __remove_from_page_cache(struct page *page) 113{ 114 struct address_space *mapping = page->mapping; 115 116 radix_tree_delete(&mapping->page_tree, page->index); 117 page->mapping = NULL; 118 mapping->nrpages--; 119 pagecache_acct(-1); 120} 121 122void remove_from_page_cache(struct page *page) 123{ 124 struct address_space *mapping = page->mapping; 125 126 if (unlikely(!PageLocked(page))) 127 PAGE_BUG(page); 128 129 write_lock_irq(&mapping->tree_lock); 130 __remove_from_page_cache(page); 131 write_unlock_irq(&mapping->tree_lock); 132} 133 134static int sync_page(void *word) 135{ 136 struct address_space *mapping; 137 struct page *page; 138 139 page = container_of((page_flags_t *)word, struct page, flags); 140 141 /* 142 * FIXME, fercrissake. What is this barrier here for? 143 */ 144 smp_mb(); 145 mapping = page_mapping(page); 146 if (mapping && mapping->a_ops && mapping->a_ops->sync_page) 147 mapping->a_ops->sync_page(page); 148 io_schedule(); 149 return 0; 150} 151 152/** 153 * filemap_fdatawrite_range - start writeback against all of a mapping's 154 * dirty pages that lie within the byte offsets <start, end> 155 * @mapping: address space structure to write 156 * @start: offset in bytes where the range starts 157 * @end : offset in bytes where the range ends 158 * 159 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as 160 * opposed to a regular memory * cleansing writeback. The difference between 161 * these two operations is that if a dirty page/buffer is encountered, it must 162 * be waited upon, and not just skipped over. 163 */ 164static int __filemap_fdatawrite_range(struct address_space *mapping, 165 loff_t start, loff_t end, int sync_mode) 166{ 167 int ret; 168 struct writeback_control wbc = { 169 .sync_mode = sync_mode, 170 .nr_to_write = mapping->nrpages * 2, 171 .start = start, 172 .end = end, 173 }; 174 175 if (!mapping_cap_writeback_dirty(mapping)) 176 return 0; 177 178 ret = do_writepages(mapping, &wbc); 179 return ret; 180} 181 182static inline int __filemap_fdatawrite(struct address_space *mapping, 183 int sync_mode) 184{ 185 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode); 186} 187 188int filemap_fdatawrite(struct address_space *mapping) 189{ 190 return __filemap_fdatawrite(mapping, WB_SYNC_ALL); 191} 192EXPORT_SYMBOL(filemap_fdatawrite); 193 194static int filemap_fdatawrite_range(struct address_space *mapping, 195 loff_t start, loff_t end) 196{ 197 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); 198} 199 200/* 201 * This is a mostly non-blocking flush. Not suitable for data-integrity 202 * purposes - I/O may not be started against all dirty pages. 203 */ 204int filemap_flush(struct address_space *mapping) 205{ 206 return __filemap_fdatawrite(mapping, WB_SYNC_NONE); 207} 208EXPORT_SYMBOL(filemap_flush); 209 210/* 211 * Wait for writeback to complete against pages indexed by start->end 212 * inclusive 213 */ 214static int wait_on_page_writeback_range(struct address_space *mapping, 215 pgoff_t start, pgoff_t end) 216{ 217 struct pagevec pvec; 218 int nr_pages; 219 int ret = 0; 220 pgoff_t index; 221 222 if (end < start) 223 return 0; 224 225 pagevec_init(&pvec, 0); 226 index = start; 227 while ((index <= end) && 228 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, 229 PAGECACHE_TAG_WRITEBACK, 230 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { 231 unsigned i; 232 233 for (i = 0; i < nr_pages; i++) { 234 struct page *page = pvec.pages[i]; 235 236 /* until radix tree lookup accepts end_index */ 237 if (page->index > end) 238 continue; 239 240 wait_on_page_writeback(page); 241 if (PageError(page)) 242 ret = -EIO; 243 } 244 pagevec_release(&pvec); 245 cond_resched(); 246 } 247 248 /* Check for outstanding write errors */ 249 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) 250 ret = -ENOSPC; 251 if (test_and_clear_bit(AS_EIO, &mapping->flags)) 252 ret = -EIO; 253 254 return ret; 255} 256 257/* 258 * Write and wait upon all the pages in the passed range. This is a "data 259 * integrity" operation. It waits upon in-flight writeout before starting and 260 * waiting upon new writeout. If there was an IO error, return it. 261 * 262 * We need to re-take i_sem during the generic_osync_inode list walk because 263 * it is otherwise livelockable. 264 */ 265int sync_page_range(struct inode *inode, struct address_space *mapping, 266 loff_t pos, size_t count) 267{ 268 pgoff_t start = pos >> PAGE_CACHE_SHIFT; 269 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; 270 int ret; 271 272 if (!mapping_cap_writeback_dirty(mapping) || !count) 273 return 0; 274 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); 275 if (ret == 0) { 276 down(&inode->i_sem); 277 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); 278 up(&inode->i_sem); 279 } 280 if (ret == 0) 281 ret = wait_on_page_writeback_range(mapping, start, end); 282 return ret; 283} 284EXPORT_SYMBOL(sync_page_range); 285 286/* 287 * Note: Holding i_sem across sync_page_range_nolock is not a good idea 288 * as it forces O_SYNC writers to different parts of the same file 289 * to be serialised right until io completion. 290 */ 291int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, 292 loff_t pos, size_t count) 293{ 294 pgoff_t start = pos >> PAGE_CACHE_SHIFT; 295 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; 296 int ret; 297 298 if (!mapping_cap_writeback_dirty(mapping) || !count) 299 return 0; 300 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); 301 if (ret == 0) 302 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); 303 if (ret == 0) 304 ret = wait_on_page_writeback_range(mapping, start, end); 305 return ret; 306} 307EXPORT_SYMBOL(sync_page_range_nolock); 308 309/** 310 * filemap_fdatawait - walk the list of under-writeback pages of the given 311 * address space and wait for all of them. 312 * 313 * @mapping: address space structure to wait for 314 */ 315int filemap_fdatawait(struct address_space *mapping) 316{ 317 loff_t i_size = i_size_read(mapping->host); 318 319 if (i_size == 0) 320 return 0; 321 322 return wait_on_page_writeback_range(mapping, 0, 323 (i_size - 1) >> PAGE_CACHE_SHIFT); 324} 325EXPORT_SYMBOL(filemap_fdatawait); 326 327int filemap_write_and_wait(struct address_space *mapping) 328{ 329 int retval = 0; 330 331 if (mapping->nrpages) { 332 retval = filemap_fdatawrite(mapping); 333 if (retval == 0) 334 retval = filemap_fdatawait(mapping); 335 } 336 return retval; 337} 338 339int filemap_write_and_wait_range(struct address_space *mapping, 340 loff_t lstart, loff_t lend) 341{ 342 int retval = 0; 343 344 if (mapping->nrpages) { 345 retval = __filemap_fdatawrite_range(mapping, lstart, lend, 346 WB_SYNC_ALL); 347 if (retval == 0) 348 retval = wait_on_page_writeback_range(mapping, 349 lstart >> PAGE_CACHE_SHIFT, 350 lend >> PAGE_CACHE_SHIFT); 351 } 352 return retval; 353} 354 355/* 356 * This function is used to add newly allocated pagecache pages: 357 * the page is new, so we can just run SetPageLocked() against it. 358 * The other page state flags were set by rmqueue(). 359 * 360 * This function does not add the page to the LRU. The caller must do that. 361 */ 362int add_to_page_cache(struct page *page, struct address_space *mapping, 363 pgoff_t offset, int gfp_mask) 364{ 365 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); 366 367 if (error == 0) { 368 write_lock_irq(&mapping->tree_lock); 369 error = radix_tree_insert(&mapping->page_tree, offset, page); 370 if (!error) { 371 page_cache_get(page); 372 SetPageLocked(page); 373 page->mapping = mapping; 374 page->index = offset; 375 mapping->nrpages++; 376 pagecache_acct(1); 377 } 378 write_unlock_irq(&mapping->tree_lock); 379 radix_tree_preload_end(); 380 } 381 return error; 382} 383 384EXPORT_SYMBOL(add_to_page_cache); 385 386int add_to_page_cache_lru(struct page *page, struct address_space *mapping, 387 pgoff_t offset, int gfp_mask) 388{ 389 int ret = add_to_page_cache(page, mapping, offset, gfp_mask); 390 if (ret == 0) 391 lru_cache_add(page); 392 return ret; 393} 394 395/* 396 * In order to wait for pages to become available there must be 397 * waitqueues associated with pages. By using a hash table of 398 * waitqueues where the bucket discipline is to maintain all 399 * waiters on the same queue and wake all when any of the pages 400 * become available, and for the woken contexts to check to be 401 * sure the appropriate page became available, this saves space 402 * at a cost of "thundering herd" phenomena during rare hash 403 * collisions. 404 */ 405static wait_queue_head_t *page_waitqueue(struct page *page) 406{ 407 const struct zone *zone = page_zone(page); 408 409 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; 410} 411 412static inline void wake_up_page(struct page *page, int bit) 413{ 414 __wake_up_bit(page_waitqueue(page), &page->flags, bit); 415} 416 417void fastcall wait_on_page_bit(struct page *page, int bit_nr) 418{ 419 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); 420 421 if (test_bit(bit_nr, &page->flags)) 422 __wait_on_bit(page_waitqueue(page), &wait, sync_page, 423 TASK_UNINTERRUPTIBLE); 424} 425EXPORT_SYMBOL(wait_on_page_bit); 426 427/** 428 * unlock_page() - unlock a locked page 429 * 430 * @page: the page 431 * 432 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). 433 * Also wakes sleepers in wait_on_page_writeback() because the wakeup 434 * mechananism between PageLocked pages and PageWriteback pages is shared. 435 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. 436 * 437 * The first mb is necessary to safely close the critical section opened by the 438 * TestSetPageLocked(), the second mb is necessary to enforce ordering between 439 * the clear_bit and the read of the waitqueue (to avoid SMP races with a 440 * parallel wait_on_page_locked()). 441 */ 442void fastcall unlock_page(struct page *page) 443{ 444 smp_mb__before_clear_bit(); 445 if (!TestClearPageLocked(page)) 446 BUG(); 447 smp_mb__after_clear_bit(); 448 wake_up_page(page, PG_locked); 449} 450EXPORT_SYMBOL(unlock_page); 451 452/* 453 * End writeback against a page. 454 */ 455void end_page_writeback(struct page *page) 456{ 457 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { 458 if (!test_clear_page_writeback(page)) 459 BUG(); 460 } 461 smp_mb__after_clear_bit(); 462 wake_up_page(page, PG_writeback); 463} 464EXPORT_SYMBOL(end_page_writeback); 465 466/* 467 * Get a lock on the page, assuming we need to sleep to get it. 468 * 469 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some 470 * random driver's requestfn sets TASK_RUNNING, we could busywait. However 471 * chances are that on the second loop, the block layer's plug list is empty, 472 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. 473 */ 474void fastcall __lock_page(struct page *page) 475{ 476 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); 477 478 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, 479 TASK_UNINTERRUPTIBLE); 480} 481EXPORT_SYMBOL(__lock_page); 482 483/* 484 * a rather lightweight function, finding and getting a reference to a 485 * hashed page atomically. 486 */ 487struct page * find_get_page(struct address_space *mapping, unsigned long offset) 488{ 489 struct page *page; 490 491 read_lock_irq(&mapping->tree_lock); 492 page = radix_tree_lookup(&mapping->page_tree, offset); 493 if (page) 494 page_cache_get(page); 495 read_unlock_irq(&mapping->tree_lock); 496 return page; 497} 498 499EXPORT_SYMBOL(find_get_page); 500 501/* 502 * Same as above, but trylock it instead of incrementing the count. 503 */ 504struct page *find_trylock_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 && TestSetPageLocked(page)) 511 page = NULL; 512 read_unlock_irq(&mapping->tree_lock); 513 return page; 514} 515 516EXPORT_SYMBOL(find_trylock_page); 517 518/** 519 * find_lock_page - locate, pin and lock a pagecache page 520 * 521 * @mapping - the address_space to search 522 * @offset - the page index 523 * 524 * Locates the desired pagecache page, locks it, increments its reference 525 * count and returns its address. 526 * 527 * Returns zero if the page was not present. find_lock_page() may sleep. 528 */ 529struct page *find_lock_page(struct address_space *mapping, 530 unsigned long offset) 531{ 532 struct page *page; 533 534 read_lock_irq(&mapping->tree_lock); 535repeat: 536 page = radix_tree_lookup(&mapping->page_tree, offset); 537 if (page) { 538 page_cache_get(page); 539 if (TestSetPageLocked(page)) { 540 read_unlock_irq(&mapping->tree_lock); 541 lock_page(page); 542 read_lock_irq(&mapping->tree_lock); 543 544 /* Has the page been truncated while we slept? */ 545 if (page->mapping != mapping || page->index != offset) { 546 unlock_page(page); 547 page_cache_release(page); 548 goto repeat; 549 } 550 } 551 } 552 read_unlock_irq(&mapping->tree_lock); 553 return page; 554} 555 556EXPORT_SYMBOL(find_lock_page); 557 558/** 559 * find_or_create_page - locate or add a pagecache page 560 * 561 * @mapping - the page's address_space 562 * @index - the page's index into the mapping 563 * @gfp_mask - page allocation mode 564 * 565 * Locates a page in the pagecache. If the page is not present, a new page 566 * is allocated using @gfp_mask and is added to the pagecache and to the VM's 567 * LRU list. The returned page is locked and has its reference count 568 * incremented. 569 * 570 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic 571 * allocation! 572 * 573 * find_or_create_page() returns the desired page's address, or zero on 574 * memory exhaustion. 575 */ 576struct page *find_or_create_page(struct address_space *mapping, 577 unsigned long index, unsigned int gfp_mask) 578{ 579 struct page *page, *cached_page = NULL; 580 int err; 581repeat: 582 page = find_lock_page(mapping, index); 583 if (!page) { 584 if (!cached_page) { 585 cached_page = alloc_page(gfp_mask); 586 if (!cached_page) 587 return NULL; 588 } 589 err = add_to_page_cache_lru(cached_page, mapping, 590 index, gfp_mask); 591 if (!err) { 592 page = cached_page; 593 cached_page = NULL; 594 } else if (err == -EEXIST) 595 goto repeat; 596 } 597 if (cached_page) 598 page_cache_release(cached_page); 599 return page; 600} 601 602EXPORT_SYMBOL(find_or_create_page); 603 604/** 605 * find_get_pages - gang pagecache lookup 606 * @mapping: The address_space to search 607 * @start: The starting page index 608 * @nr_pages: The maximum number of pages 609 * @pages: Where the resulting pages are placed 610 * 611 * find_get_pages() will search for and return a group of up to 612 * @nr_pages pages in the mapping. The pages are placed at @pages. 613 * find_get_pages() takes a reference against the returned pages. 614 * 615 * The search returns a group of mapping-contiguous pages with ascending 616 * indexes. There may be holes in the indices due to not-present pages. 617 * 618 * find_get_pages() returns the number of pages which were found. 619 */ 620unsigned find_get_pages(struct address_space *mapping, pgoff_t start, 621 unsigned int nr_pages, struct page **pages) 622{ 623 unsigned int i; 624 unsigned int ret; 625 626 read_lock_irq(&mapping->tree_lock); 627 ret = radix_tree_gang_lookup(&mapping->page_tree, 628 (void **)pages, start, nr_pages); 629 for (i = 0; i < ret; i++) 630 page_cache_get(pages[i]); 631 read_unlock_irq(&mapping->tree_lock); 632 return ret; 633} 634 635/* 636 * Like find_get_pages, except we only return pages which are tagged with 637 * `tag'. We update *index to index the next page for the traversal. 638 */ 639unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, 640 int tag, unsigned int nr_pages, struct page **pages) 641{ 642 unsigned int i; 643 unsigned int ret; 644 645 read_lock_irq(&mapping->tree_lock); 646 ret = radix_tree_gang_lookup_tag(&mapping->page_tree, 647 (void **)pages, *index, nr_pages, tag); 648 for (i = 0; i < ret; i++) 649 page_cache_get(pages[i]); 650 if (ret) 651 *index = pages[ret - 1]->index + 1; 652 read_unlock_irq(&mapping->tree_lock); 653 return ret; 654} 655 656/* 657 * Same as grab_cache_page, but do not wait if the page is unavailable. 658 * This is intended for speculative data generators, where the data can 659 * be regenerated if the page couldn't be grabbed. This routine should 660 * be safe to call while holding the lock for another page. 661 * 662 * Clear __GFP_FS when allocating the page to avoid recursion into the fs 663 * and deadlock against the caller's locked page. 664 */ 665struct page * 666grab_cache_page_nowait(struct address_space *mapping, unsigned long index) 667{ 668 struct page *page = find_get_page(mapping, index); 669 unsigned int gfp_mask; 670 671 if (page) { 672 if (!TestSetPageLocked(page)) 673 return page; 674 page_cache_release(page); 675 return NULL; 676 } 677 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS; 678 page = alloc_pages(gfp_mask, 0); 679 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) { 680 page_cache_release(page); 681 page = NULL; 682 } 683 return page; 684} 685 686EXPORT_SYMBOL(grab_cache_page_nowait); 687 688/* 689 * This is a generic file read routine, and uses the 690 * mapping->a_ops->readpage() function for the actual low-level 691 * stuff. 692 * 693 * This is really ugly. But the goto's actually try to clarify some 694 * of the logic when it comes to error handling etc. 695 * 696 * Note the struct file* is only passed for the use of readpage. It may be 697 * NULL. 698 */ 699void do_generic_mapping_read(struct address_space *mapping, 700 struct file_ra_state *_ra, 701 struct file *filp, 702 loff_t *ppos, 703 read_descriptor_t *desc, 704 read_actor_t actor) 705{ 706 struct inode *inode = mapping->host; 707 unsigned long index; 708 unsigned long end_index; 709 unsigned long offset; 710 unsigned long last_index; 711 unsigned long next_index; 712 unsigned long prev_index; 713 loff_t isize; 714 struct page *cached_page; 715 int error; 716 struct file_ra_state ra = *_ra; 717 718 cached_page = NULL; 719 index = *ppos >> PAGE_CACHE_SHIFT; 720 next_index = index; 721 prev_index = ra.prev_page; 722 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; 723 offset = *ppos & ~PAGE_CACHE_MASK; 724 725 isize = i_size_read(inode); 726 if (!isize) 727 goto out; 728 729 end_index = (isize - 1) >> PAGE_CACHE_SHIFT; 730 for (;;) { 731 struct page *page; 732 unsigned long nr, ret; 733 734 /* nr is the maximum number of bytes to copy from this page */ 735 nr = PAGE_CACHE_SIZE; 736 if (index >= end_index) { 737 if (index > end_index) 738 goto out; 739 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; 740 if (nr <= offset) { 741 goto out; 742 } 743 } 744 nr = nr - offset; 745 746 cond_resched(); 747 if (index == next_index) 748 next_index = page_cache_readahead(mapping, &ra, filp, 749 index, last_index - index); 750 751find_page: 752 page = find_get_page(mapping, index); 753 if (unlikely(page == NULL)) { 754 handle_ra_miss(mapping, &ra, index); 755 goto no_cached_page; 756 } 757 if (!PageUptodate(page)) 758 goto page_not_up_to_date; 759page_ok: 760 761 /* If users can be writing to this page using arbitrary 762 * virtual addresses, take care about potential aliasing 763 * before reading the page on the kernel side. 764 */ 765 if (mapping_writably_mapped(mapping)) 766 flush_dcache_page(page); 767 768 /* 769 * When (part of) the same page is read multiple times 770 * in succession, only mark it as accessed the first time. 771 */ 772 if (prev_index != index) 773 mark_page_accessed(page); 774 prev_index = index; 775 776 /* 777 * Ok, we have the page, and it's up-to-date, so 778 * now we can copy it to user space... 779 * 780 * The actor routine returns how many bytes were actually used.. 781 * NOTE! This may not be the same as how much of a user buffer 782 * we filled up (we may be padding etc), so we can only update 783 * "pos" here (the actor routine has to update the user buffer 784 * pointers and the remaining count). 785 */ 786 ret = actor(desc, page, offset, nr); 787 offset += ret; 788 index += offset >> PAGE_CACHE_SHIFT; 789 offset &= ~PAGE_CACHE_MASK; 790 791 page_cache_release(page); 792 if (ret == nr && desc->count) 793 continue; 794 goto out; 795 796page_not_up_to_date: 797 /* Get exclusive access to the page ... */ 798 lock_page(page); 799 800 /* Did it get unhashed before we got the lock? */ 801 if (!page->mapping) { 802 unlock_page(page); 803 page_cache_release(page); 804 continue; 805 } 806 807 /* Did somebody else fill it already? */ 808 if (PageUptodate(page)) { 809 unlock_page(page); 810 goto page_ok; 811 } 812 813readpage: 814 /* Start the actual read. The read will unlock the page. */ 815 error = mapping->a_ops->readpage(filp, page); 816 817 if (unlikely(error)) 818 goto readpage_error; 819 820 if (!PageUptodate(page)) { 821 lock_page(page); 822 if (!PageUptodate(page)) { 823 if (page->mapping == NULL) { 824 /* 825 * invalidate_inode_pages got it 826 */ 827 unlock_page(page); 828 page_cache_release(page); 829 goto find_page; 830 } 831 unlock_page(page); 832 error = -EIO; 833 goto readpage_error; 834 } 835 unlock_page(page); 836 } 837 838 /* 839 * i_size must be checked after we have done ->readpage. 840 * 841 * Checking i_size after the readpage allows us to calculate 842 * the correct value for "nr", which means the zero-filled 843 * part of the page is not copied back to userspace (unless 844 * another truncate extends the file - this is desired though). 845 */ 846 isize = i_size_read(inode); 847 end_index = (isize - 1) >> PAGE_CACHE_SHIFT; 848 if (unlikely(!isize || index > end_index)) { 849 page_cache_release(page); 850 goto out; 851 } 852 853 /* nr is the maximum number of bytes to copy from this page */ 854 nr = PAGE_CACHE_SIZE; 855 if (index == end_index) { 856 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; 857 if (nr <= offset) { 858 page_cache_release(page); 859 goto out; 860 } 861 } 862 nr = nr - offset; 863 goto page_ok; 864 865readpage_error: 866 /* UHHUH! A synchronous read error occurred. Report it */ 867 desc->error = error; 868 page_cache_release(page); 869 goto out; 870 871no_cached_page: 872 /* 873 * Ok, it wasn't cached, so we need to create a new 874 * page.. 875 */ 876 if (!cached_page) { 877 cached_page = page_cache_alloc_cold(mapping); 878 if (!cached_page) { 879 desc->error = -ENOMEM; 880 goto out; 881 } 882 } 883 error = add_to_page_cache_lru(cached_page, mapping, 884 index, GFP_KERNEL); 885 if (error) { 886 if (error == -EEXIST) 887 goto find_page; 888 desc->error = error; 889 goto out; 890 } 891 page = cached_page; 892 cached_page = NULL; 893 goto readpage; 894 } 895 896out: 897 *_ra = ra; 898 899 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 900 if (cached_page) 901 page_cache_release(cached_page); 902 if (filp) 903 file_accessed(filp); 904} 905 906EXPORT_SYMBOL(do_generic_mapping_read); 907 908int file_read_actor(read_descriptor_t *desc, struct page *page, 909 unsigned long offset, unsigned long size) 910{ 911 char *kaddr; 912 unsigned long left, count = desc->count; 913 914 if (size > count) 915 size = count; 916 917 /* 918 * Faults on the destination of a read are common, so do it before 919 * taking the kmap. 920 */ 921 if (!fault_in_pages_writeable(desc->arg.buf, size)) { 922 kaddr = kmap_atomic(page, KM_USER0); 923 left = __copy_to_user_inatomic(desc->arg.buf, 924 kaddr + offset, size); 925 kunmap_atomic(kaddr, KM_USER0); 926 if (left == 0) 927 goto success; 928 } 929 930 /* Do it the slow way */ 931 kaddr = kmap(page); 932 left = __copy_to_user(desc->arg.buf, kaddr + offset, size); 933 kunmap(page); 934 935 if (left) { 936 size -= left; 937 desc->error = -EFAULT; 938 } 939success: 940 desc->count = count - size; 941 desc->written += size; 942 desc->arg.buf += size; 943 return size; 944} 945 946/* 947 * This is the "read()" routine for all filesystems 948 * that can use the page cache directly. 949 */ 950ssize_t 951__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, 952 unsigned long nr_segs, loff_t *ppos) 953{ 954 struct file *filp = iocb->ki_filp; 955 ssize_t retval; 956 unsigned long seg; 957 size_t count; 958 959 count = 0; 960 for (seg = 0; seg < nr_segs; seg++) { 961 const struct iovec *iv = &iov[seg]; 962 963 /* 964 * If any segment has a negative length, or the cumulative 965 * length ever wraps negative then return -EINVAL. 966 */ 967 count += iv->iov_len; 968 if (unlikely((ssize_t)(count|iv->iov_len) < 0)) 969 return -EINVAL; 970 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) 971 continue; 972 if (seg == 0) 973 return -EFAULT; 974 nr_segs = seg; 975 count -= iv->iov_len; /* This segment is no good */ 976 break; 977 } 978 979 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ 980 if (filp->f_flags & O_DIRECT) { 981 loff_t pos = *ppos, size; 982 struct address_space *mapping; 983 struct inode *inode; 984 985 mapping = filp->f_mapping; 986 inode = mapping->host; 987 retval = 0; 988 if (!count) 989 goto out; /* skip atime */ 990 size = i_size_read(inode); 991 if (pos < size) { 992 retval = generic_file_direct_IO(READ, iocb, 993 iov, pos, nr_segs); 994 if (retval >= 0 && !is_sync_kiocb(iocb)) 995 retval = -EIOCBQUEUED; 996 if (retval > 0) 997 *ppos = pos + retval; 998 } 999 file_accessed(filp); 1000 goto out; 1001 } 1002 1003 retval = 0; 1004 if (count) { 1005 for (seg = 0; seg < nr_segs; seg++) { 1006 read_descriptor_t desc; 1007 1008 desc.written = 0; 1009 desc.arg.buf = iov[seg].iov_base; 1010 desc.count = iov[seg].iov_len; 1011 if (desc.count == 0) 1012 continue; 1013 desc.error = 0; 1014 do_generic_file_read(filp,ppos,&desc,file_read_actor); 1015 retval += desc.written; 1016 if (!retval) { 1017 retval = desc.error; 1018 break; 1019 } 1020 } 1021 } 1022out: 1023 return retval; 1024} 1025 1026EXPORT_SYMBOL(__generic_file_aio_read); 1027 1028ssize_t 1029generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) 1030{ 1031 struct iovec local_iov = { .iov_base = buf, .iov_len = count }; 1032 1033 BUG_ON(iocb->ki_pos != pos); 1034 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); 1035} 1036 1037EXPORT_SYMBOL(generic_file_aio_read); 1038 1039ssize_t 1040generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1041{ 1042 struct iovec local_iov = { .iov_base = buf, .iov_len = count }; 1043 struct kiocb kiocb; 1044 ssize_t ret; 1045 1046 init_sync_kiocb(&kiocb, filp); 1047 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); 1048 if (-EIOCBQUEUED == ret) 1049 ret = wait_on_sync_kiocb(&kiocb); 1050 return ret; 1051} 1052 1053EXPORT_SYMBOL(generic_file_read); 1054 1055int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) 1056{ 1057 ssize_t written; 1058 unsigned long count = desc->count; 1059 struct file *file = desc->arg.data; 1060 1061 if (size > count) 1062 size = count; 1063 1064 written = file->f_op->sendpage(file, page, offset, 1065 size, &file->f_pos, size<count); 1066 if (written < 0) { 1067 desc->error = written; 1068 written = 0; 1069 } 1070 desc->count = count - written; 1071 desc->written += written; 1072 return written; 1073} 1074 1075ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, 1076 size_t count, read_actor_t actor, void *target) 1077{ 1078 read_descriptor_t desc; 1079 1080 if (!count) 1081 return 0; 1082 1083 desc.written = 0; 1084 desc.count = count; 1085 desc.arg.data = target; 1086 desc.error = 0; 1087 1088 do_generic_file_read(in_file, ppos, &desc, actor); 1089 if (desc.written) 1090 return desc.written; 1091 return desc.error; 1092} 1093 1094EXPORT_SYMBOL(generic_file_sendfile); 1095 1096static ssize_t 1097do_readahead(struct address_space *mapping, struct file *filp, 1098 unsigned long index, unsigned long nr) 1099{ 1100 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) 1101 return -EINVAL; 1102 1103 force_page_cache_readahead(mapping, filp, index, 1104 max_sane_readahead(nr)); 1105 return 0; 1106} 1107 1108asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) 1109{ 1110 ssize_t ret; 1111 struct file *file; 1112 1113 ret = -EBADF; 1114 file = fget(fd); 1115 if (file) { 1116 if (file->f_mode & FMODE_READ) { 1117 struct address_space *mapping = file->f_mapping; 1118 unsigned long start = offset >> PAGE_CACHE_SHIFT; 1119 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT; 1120 unsigned long len = end - start + 1; 1121 ret = do_readahead(mapping, file, start, len); 1122 } 1123 fput(file); 1124 } 1125 return ret; 1126} 1127 1128#ifdef CONFIG_MMU 1129/* 1130 * This adds the requested page to the page cache if it isn't already there, 1131 * and schedules an I/O to read in its contents from disk. 1132 */ 1133static int FASTCALL(page_cache_read(struct file * file, unsigned long offset)); 1134static int fastcall page_cache_read(struct file * file, unsigned long offset) 1135{ 1136 struct address_space *mapping = file->f_mapping; 1137 struct page *page; 1138 int error; 1139 1140 page = page_cache_alloc_cold(mapping); 1141 if (!page) 1142 return -ENOMEM; 1143 1144 error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); 1145 if (!error) { 1146 error = mapping->a_ops->readpage(file, page); 1147 page_cache_release(page); 1148 return error; 1149 } 1150 1151 /* 1152 * We arrive here in the unlikely event that someone 1153 * raced with us and added our page to the cache first 1154 * or we are out of memory for radix-tree nodes. 1155 */ 1156 page_cache_release(page); 1157 return error == -EEXIST ? 0 : error; 1158} 1159 1160#define MMAP_LOTSAMISS (100) 1161 1162/* 1163 * filemap_nopage() is invoked via the vma operations vector for a 1164 * mapped memory region to read in file data during a page fault. 1165 * 1166 * The goto's are kind of ugly, but this streamlines the normal case of having 1167 * it in the page cache, and handles the special cases reasonably without 1168 * having a lot of duplicated code. 1169 */ 1170struct page *filemap_nopage(struct vm_area_struct *area, 1171 unsigned long address, int *type) 1172{ 1173 int error; 1174 struct file *file = area->vm_file; 1175 struct address_space *mapping = file->f_mapping; 1176 struct file_ra_state *ra = &file->f_ra; 1177 struct inode *inode = mapping->host; 1178 struct page *page; 1179 unsigned long size, pgoff; 1180 int did_readaround = 0, majmin = VM_FAULT_MINOR; 1181 1182 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; 1183 1184retry_all: 1185 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 1186 if (pgoff >= size) 1187 goto outside_data_content; 1188 1189 /* If we don't want any read-ahead, don't bother */ 1190 if (VM_RandomReadHint(area)) 1191 goto no_cached_page; 1192 1193 /* 1194 * The readahead code wants to be told about each and every page 1195 * so it can build and shrink its windows appropriately 1196 * 1197 * For sequential accesses, we use the generic readahead logic. 1198 */ 1199 if (VM_SequentialReadHint(area)) 1200 page_cache_readahead(mapping, ra, file, pgoff, 1); 1201 1202 /* 1203 * Do we have something in the page cache already? 1204 */ 1205retry_find: 1206 page = find_get_page(mapping, pgoff); 1207 if (!page) { 1208 unsigned long ra_pages; 1209 1210 if (VM_SequentialReadHint(area)) { 1211 handle_ra_miss(mapping, ra, pgoff); 1212 goto no_cached_page; 1213 } 1214 ra->mmap_miss++; 1215 1216 /* 1217 * Do we miss much more than hit in this file? If so, 1218 * stop bothering with read-ahead. It will only hurt. 1219 */ 1220 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS) 1221 goto no_cached_page; 1222 1223 /* 1224 * To keep the pgmajfault counter straight, we need to 1225 * check did_readaround, as this is an inner loop. 1226 */ 1227 if (!did_readaround) { 1228 majmin = VM_FAULT_MAJOR; 1229 inc_page_state(pgmajfault); 1230 } 1231 did_readaround = 1; 1232 ra_pages = max_sane_readahead(file->f_ra.ra_pages); 1233 if (ra_pages) { 1234 pgoff_t start = 0; 1235 1236 if (pgoff > ra_pages / 2) 1237 start = pgoff - ra_pages / 2; 1238 do_page_cache_readahead(mapping, file, start, ra_pages); 1239 } 1240 page = find_get_page(mapping, pgoff); 1241 if (!page) 1242 goto no_cached_page; 1243 } 1244 1245 if (!did_readaround) 1246 ra->mmap_hit++; 1247 1248 /* 1249 * Ok, found a page in the page cache, now we need to check 1250 * that it's up-to-date. 1251 */ 1252 if (!PageUptodate(page)) 1253 goto page_not_uptodate; 1254 1255success: 1256 /* 1257 * Found the page and have a reference on it. 1258 */ 1259 mark_page_accessed(page); 1260 if (type) 1261 *type = majmin; 1262 return page; 1263 1264outside_data_content: 1265 /* 1266 * An external ptracer can access pages that normally aren't 1267 * accessible.. 1268 */ 1269 if (area->vm_mm == current->mm) 1270 return NULL; 1271 /* Fall through to the non-read-ahead case */ 1272no_cached_page: 1273 /* 1274 * We're only likely to ever get here if MADV_RANDOM is in 1275 * effect. 1276 */ 1277 error = page_cache_read(file, pgoff); 1278 grab_swap_token(); 1279 1280 /* 1281 * The page we want has now been added to the page cache. 1282 * In the unlikely event that someone removed it in the 1283 * meantime, we'll just come back here and read it again. 1284 */ 1285 if (error >= 0) 1286 goto retry_find; 1287 1288 /* 1289 * An error return from page_cache_read can result if the 1290 * system is low on memory, or a problem occurs while trying 1291 * to schedule I/O. 1292 */ 1293 if (error == -ENOMEM) 1294 return NOPAGE_OOM; 1295 return NULL; 1296 1297page_not_uptodate: 1298 if (!did_readaround) { 1299 majmin = VM_FAULT_MAJOR; 1300 inc_page_state(pgmajfault); 1301 } 1302 lock_page(page); 1303 1304 /* Did it get unhashed while we waited for it? */ 1305 if (!page->mapping) { 1306 unlock_page(page); 1307 page_cache_release(page); 1308 goto retry_all; 1309 } 1310 1311 /* Did somebody else get it up-to-date? */ 1312 if (PageUptodate(page)) { 1313 unlock_page(page); 1314 goto success; 1315 } 1316 1317 if (!mapping->a_ops->readpage(file, page)) { 1318 wait_on_page_locked(page); 1319 if (PageUptodate(page)) 1320 goto success; 1321 } 1322 1323 /* 1324 * Umm, take care of errors if the page isn't up-to-date. 1325 * Try to re-read it _once_. We do this synchronously, 1326 * because there really aren't any performance issues here 1327 * and we need to check for errors. 1328 */ 1329 lock_page(page); 1330 1331 /* Somebody truncated the page on us? */ 1332 if (!page->mapping) { 1333 unlock_page(page); 1334 page_cache_release(page); 1335 goto retry_all; 1336 } 1337 1338 /* Somebody else successfully read it in? */ 1339 if (PageUptodate(page)) { 1340 unlock_page(page); 1341 goto success; 1342 } 1343 ClearPageError(page); 1344 if (!mapping->a_ops->readpage(file, page)) { 1345 wait_on_page_locked(page); 1346 if (PageUptodate(page)) 1347 goto success; 1348 } 1349 1350 /* 1351 * Things didn't work out. Return zero to tell the 1352 * mm layer so, possibly freeing the page cache page first. 1353 */ 1354 page_cache_release(page); 1355 return NULL; 1356} 1357 1358EXPORT_SYMBOL(filemap_nopage); 1359 1360static struct page * filemap_getpage(struct file *file, unsigned long pgoff, 1361 int nonblock) 1362{ 1363 struct address_space *mapping = file->f_mapping; 1364 struct page *page; 1365 int error; 1366 1367 /* 1368 * Do we have something in the page cache already? 1369 */ 1370retry_find: 1371 page = find_get_page(mapping, pgoff); 1372 if (!page) { 1373 if (nonblock) 1374 return NULL; 1375 goto no_cached_page; 1376 } 1377 1378 /* 1379 * Ok, found a page in the page cache, now we need to check 1380 * that it's up-to-date. 1381 */ 1382 if (!PageUptodate(page)) { 1383 if (nonblock) { 1384 page_cache_release(page); 1385 return NULL; 1386 } 1387 goto page_not_uptodate; 1388 } 1389 1390success: 1391 /* 1392 * Found the page and have a reference on it. 1393 */ 1394 mark_page_accessed(page); 1395 return page; 1396 1397no_cached_page: 1398 error = page_cache_read(file, pgoff); 1399 1400 /* 1401 * The page we want has now been added to the page cache. 1402 * In the unlikely event that someone removed it in the 1403 * meantime, we'll just come back here and read it again. 1404 */ 1405 if (error >= 0) 1406 goto retry_find; 1407 1408 /* 1409 * An error return from page_cache_read can result if the 1410 * system is low on memory, or a problem occurs while trying 1411 * to schedule I/O. 1412 */ 1413 return NULL; 1414 1415page_not_uptodate: 1416 lock_page(page); 1417 1418 /* Did it get unhashed while we waited for it? */ 1419 if (!page->mapping) { 1420 unlock_page(page); 1421 goto err; 1422 } 1423 1424 /* Did somebody else get it up-to-date? */ 1425 if (PageUptodate(page)) { 1426 unlock_page(page); 1427 goto success; 1428 } 1429 1430 if (!mapping->a_ops->readpage(file, page)) { 1431 wait_on_page_locked(page); 1432 if (PageUptodate(page)) 1433 goto success; 1434 } 1435 1436 /* 1437 * Umm, take care of errors if the page isn't up-to-date. 1438 * Try to re-read it _once_. We do this synchronously, 1439 * because there really aren't any performance issues here 1440 * and we need to check for errors. 1441 */ 1442 lock_page(page); 1443 1444 /* Somebody truncated the page on us? */ 1445 if (!page->mapping) { 1446 unlock_page(page); 1447 goto err; 1448 } 1449 /* Somebody else successfully read it in? */ 1450 if (PageUptodate(page)) { 1451 unlock_page(page); 1452 goto success; 1453 } 1454 1455 ClearPageError(page); 1456 if (!mapping->a_ops->readpage(file, page)) { 1457 wait_on_page_locked(page); 1458 if (PageUptodate(page)) 1459 goto success; 1460 } 1461 1462 /* 1463 * Things didn't work out. Return zero to tell the 1464 * mm layer so, possibly freeing the page cache page first. 1465 */ 1466err: 1467 page_cache_release(page); 1468 1469 return NULL; 1470} 1471 1472int filemap_populate(struct vm_area_struct *vma, unsigned long addr, 1473 unsigned long len, pgprot_t prot, unsigned long pgoff, 1474 int nonblock) 1475{ 1476 struct file *file = vma->vm_file; 1477 struct address_space *mapping = file->f_mapping; 1478 struct inode *inode = mapping->host; 1479 unsigned long size; 1480 struct mm_struct *mm = vma->vm_mm; 1481 struct page *page; 1482 int err; 1483 1484 if (!nonblock) 1485 force_page_cache_readahead(mapping, vma->vm_file, 1486 pgoff, len >> PAGE_CACHE_SHIFT); 1487 1488repeat: 1489 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 1490 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) 1491 return -EINVAL; 1492 1493 page = filemap_getpage(file, pgoff, nonblock); 1494 if (!page && !nonblock) 1495 return -ENOMEM; 1496 if (page) { 1497 err = install_page(mm, vma, addr, page, prot); 1498 if (err) { 1499 page_cache_release(page); 1500 return err; 1501 } 1502 } else { 1503 err = install_file_pte(mm, vma, addr, pgoff, prot); 1504 if (err) 1505 return err; 1506 } 1507 1508 len -= PAGE_SIZE; 1509 addr += PAGE_SIZE; 1510 pgoff++; 1511 if (len) 1512 goto repeat; 1513 1514 return 0; 1515} 1516 1517struct vm_operations_struct generic_file_vm_ops = { 1518 .nopage = filemap_nopage, 1519 .populate = filemap_populate, 1520}; 1521 1522/* This is used for a general mmap of a disk file */ 1523 1524int generic_file_mmap(struct file * file, struct vm_area_struct * vma) 1525{ 1526 struct address_space *mapping = file->f_mapping; 1527 1528 if (!mapping->a_ops->readpage) 1529 return -ENOEXEC; 1530 file_accessed(file); 1531 vma->vm_ops = &generic_file_vm_ops; 1532 return 0; 1533} 1534EXPORT_SYMBOL(filemap_populate); 1535 1536/* 1537 * This is for filesystems which do not implement ->writepage. 1538 */ 1539int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) 1540{ 1541 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) 1542 return -EINVAL; 1543 return generic_file_mmap(file, vma); 1544} 1545#else 1546int generic_file_mmap(struct file * file, struct vm_area_struct * vma) 1547{ 1548 return -ENOSYS; 1549} 1550int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) 1551{ 1552 return -ENOSYS; 1553} 1554#endif /* CONFIG_MMU */ 1555 1556EXPORT_SYMBOL(generic_file_mmap); 1557EXPORT_SYMBOL(generic_file_readonly_mmap); 1558 1559static inline struct page *__read_cache_page(struct address_space *mapping, 1560 unsigned long index, 1561 int (*filler)(void *,struct page*), 1562 void *data) 1563{ 1564 struct page *page, *cached_page = NULL; 1565 int err; 1566repeat: 1567 page = find_get_page(mapping, index); 1568 if (!page) { 1569 if (!cached_page) { 1570 cached_page = page_cache_alloc_cold(mapping); 1571 if (!cached_page) 1572 return ERR_PTR(-ENOMEM); 1573 } 1574 err = add_to_page_cache_lru(cached_page, mapping, 1575 index, GFP_KERNEL); 1576 if (err == -EEXIST) 1577 goto repeat; 1578 if (err < 0) { 1579 /* Presumably ENOMEM for radix tree node */ 1580 page_cache_release(cached_page); 1581 return ERR_PTR(err); 1582 } 1583 page = cached_page; 1584 cached_page = NULL; 1585 err = filler(data, page); 1586 if (err < 0) { 1587 page_cache_release(page); 1588 page = ERR_PTR(err); 1589 } 1590 } 1591 if (cached_page) 1592 page_cache_release(cached_page); 1593 return page; 1594} 1595 1596/* 1597 * Read into the page cache. If a page already exists, 1598 * and PageUptodate() is not set, try to fill the page. 1599 */ 1600struct page *read_cache_page(struct address_space *mapping, 1601 unsigned long index, 1602 int (*filler)(void *,struct page*), 1603 void *data) 1604{ 1605 struct page *page; 1606 int err; 1607 1608retry: 1609 page = __read_cache_page(mapping, index, filler, data); 1610 if (IS_ERR(page)) 1611 goto out; 1612 mark_page_accessed(page); 1613 if (PageUptodate(page)) 1614 goto out; 1615 1616 lock_page(page); 1617 if (!page->mapping) { 1618 unlock_page(page); 1619 page_cache_release(page); 1620 goto retry; 1621 } 1622 if (PageUptodate(page)) { 1623 unlock_page(page); 1624 goto out; 1625 } 1626 err = filler(data, page); 1627 if (err < 0) { 1628 page_cache_release(page); 1629 page = ERR_PTR(err); 1630 } 1631 out: 1632 return page; 1633} 1634 1635EXPORT_SYMBOL(read_cache_page); 1636 1637/* 1638 * If the page was newly created, increment its refcount and add it to the 1639 * caller's lru-buffering pagevec. This function is specifically for 1640 * generic_file_write(). 1641 */ 1642static inline struct page * 1643__grab_cache_page(struct address_space *mapping, unsigned long index, 1644 struct page **cached_page, struct pagevec *lru_pvec) 1645{ 1646 int err; 1647 struct page *page; 1648repeat: 1649 page = find_lock_page(mapping, index); 1650 if (!page) { 1651 if (!*cached_page) { 1652 *cached_page = page_cache_alloc(mapping); 1653 if (!*cached_page) 1654 return NULL; 1655 } 1656 err = add_to_page_cache(*cached_page, mapping, 1657 index, GFP_KERNEL); 1658 if (err == -EEXIST) 1659 goto repeat; 1660 if (err == 0) { 1661 page = *cached_page; 1662 page_cache_get(page); 1663 if (!pagevec_add(lru_pvec, page)) 1664 __pagevec_lru_add(lru_pvec); 1665 *cached_page = NULL; 1666 } 1667 } 1668 return page; 1669} 1670 1671/* 1672 * The logic we want is 1673 * 1674 * if suid or (sgid and xgrp) 1675 * remove privs 1676 */ 1677int remove_suid(struct dentry *dentry) 1678{ 1679 mode_t mode = dentry->d_inode->i_mode; 1680 int kill = 0; 1681 int result = 0; 1682 1683 /* suid always must be killed */ 1684 if (unlikely(mode & S_ISUID)) 1685 kill = ATTR_KILL_SUID; 1686 1687 /* 1688 * sgid without any exec bits is just a mandatory locking mark; leave 1689 * it alone. If some exec bits are set, it's a real sgid; kill it. 1690 */ 1691 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) 1692 kill |= ATTR_KILL_SGID; 1693 1694 if (unlikely(kill && !capable(CAP_FSETID))) { 1695 struct iattr newattrs; 1696 1697 newattrs.ia_valid = ATTR_FORCE | kill; 1698 result = notify_change(dentry, &newattrs); 1699 } 1700 return result; 1701} 1702EXPORT_SYMBOL(remove_suid); 1703 1704/* 1705 * Copy as much as we can into the page and return the number of bytes which 1706 * were sucessfully copied. If a fault is encountered then clear the page 1707 * out to (offset+bytes) and return the number of bytes which were copied. 1708 */ 1709static inline size_t 1710filemap_copy_from_user(struct page *page, unsigned long offset, 1711 const char __user *buf, unsigned bytes) 1712{ 1713 char *kaddr; 1714 int left; 1715 1716 kaddr = kmap_atomic(page, KM_USER0); 1717 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); 1718 kunmap_atomic(kaddr, KM_USER0); 1719 1720 if (left != 0) { 1721 /* Do it the slow way */ 1722 kaddr = kmap(page); 1723 left = __copy_from_user(kaddr + offset, buf, bytes); 1724 kunmap(page); 1725 } 1726 return bytes - left; 1727} 1728 1729static size_t 1730__filemap_copy_from_user_iovec(char *vaddr, 1731 const struct iovec *iov, size_t base, size_t bytes) 1732{ 1733 size_t copied = 0, left = 0; 1734 1735 while (bytes) { 1736 char __user *buf = iov->iov_base + base; 1737 int copy = min(bytes, iov->iov_len - base); 1738 1739 base = 0; 1740 left = __copy_from_user_inatomic(vaddr, buf, copy); 1741 copied += copy; 1742 bytes -= copy; 1743 vaddr += copy; 1744 iov++; 1745 1746 if (unlikely(left)) { 1747 /* zero the rest of the target like __copy_from_user */ 1748 if (bytes) 1749 memset(vaddr, 0, bytes); 1750 break; 1751 } 1752 } 1753 return copied - left; 1754} 1755 1756/* 1757 * This has the same sideeffects and return value as filemap_copy_from_user(). 1758 * The difference is that on a fault we need to memset the remainder of the 1759 * page (out to offset+bytes), to emulate filemap_copy_from_user()'s 1760 * single-segment behaviour. 1761 */ 1762static inline size_t 1763filemap_copy_from_user_iovec(struct page *page, unsigned long offset, 1764 const struct iovec *iov, size_t base, size_t bytes) 1765{ 1766 char *kaddr; 1767 size_t copied; 1768 1769 kaddr = kmap_atomic(page, KM_USER0); 1770 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, 1771 base, bytes); 1772 kunmap_atomic(kaddr, KM_USER0); 1773 if (copied != bytes) { 1774 kaddr = kmap(page); 1775 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, 1776 base, bytes); 1777 kunmap(page); 1778 } 1779 return copied; 1780} 1781 1782static inline void 1783filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) 1784{ 1785 const struct iovec *iov = *iovp; 1786 size_t base = *basep; 1787 1788 while (bytes) { 1789 int copy = min(bytes, iov->iov_len - base); 1790 1791 bytes -= copy; 1792 base += copy; 1793 if (iov->iov_len == base) { 1794 iov++; 1795 base = 0; 1796 } 1797 } 1798 *iovp = iov; 1799 *basep = base; 1800} 1801 1802/* 1803 * Performs necessary checks before doing a write 1804 * 1805 * Can adjust writing position aor amount of bytes to write. 1806 * Returns appropriate error code that caller should return or 1807 * zero in case that write should be allowed. 1808 */ 1809inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) 1810{ 1811 struct inode *inode = file->f_mapping->host; 1812 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1813 1814 if (unlikely(*pos < 0)) 1815 return -EINVAL; 1816 1817 if (unlikely(file->f_error)) { 1818 int err = file->f_error; 1819 file->f_error = 0; 1820 return err; 1821 } 1822 1823 if (!isblk) { 1824 /* FIXME: this is for backwards compatibility with 2.4 */ 1825 if (file->f_flags & O_APPEND) 1826 *pos = i_size_read(inode); 1827 1828 if (limit != RLIM_INFINITY) { 1829 if (*pos >= limit) { 1830 send_sig(SIGXFSZ, current, 0); 1831 return -EFBIG; 1832 } 1833 if (*count > limit - (typeof(limit))*pos) { 1834 *count = limit - (typeof(limit))*pos; 1835 } 1836 } 1837 } 1838 1839 /* 1840 * LFS rule 1841 */ 1842 if (unlikely(*pos + *count > MAX_NON_LFS && 1843 !(file->f_flags & O_LARGEFILE))) { 1844 if (*pos >= MAX_NON_LFS) { 1845 send_sig(SIGXFSZ, current, 0); 1846 return -EFBIG; 1847 } 1848 if (*count > MAX_NON_LFS - (unsigned long)*pos) { 1849 *count = MAX_NON_LFS - (unsigned long)*pos; 1850 } 1851 } 1852 1853 /* 1854 * Are we about to exceed the fs block limit ? 1855 * 1856 * If we have written data it becomes a short write. If we have 1857 * exceeded without writing data we send a signal and return EFBIG. 1858 * Linus frestrict idea will clean these up nicely.. 1859 */ 1860 if (likely(!isblk)) { 1861 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { 1862 if (*count || *pos > inode->i_sb->s_maxbytes) { 1863 send_sig(SIGXFSZ, current, 0); 1864 return -EFBIG; 1865 } 1866 /* zero-length writes at ->s_maxbytes are OK */ 1867 } 1868 1869 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) 1870 *count = inode->i_sb->s_maxbytes - *pos; 1871 } else { 1872 loff_t isize; 1873 if (bdev_read_only(I_BDEV(inode))) 1874 return -EPERM; 1875 isize = i_size_read(inode); 1876 if (*pos >= isize) { 1877 if (*count || *pos > isize) 1878 return -ENOSPC; 1879 } 1880 1881 if (*pos + *count > isize) 1882 *count = isize - *pos; 1883 } 1884 return 0; 1885} 1886EXPORT_SYMBOL(generic_write_checks); 1887 1888ssize_t 1889generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, 1890 unsigned long *nr_segs, loff_t pos, loff_t *ppos, 1891 size_t count, size_t ocount) 1892{ 1893 struct file *file = iocb->ki_filp; 1894 struct address_space *mapping = file->f_mapping; 1895 struct inode *inode = mapping->host; 1896 ssize_t written; 1897 1898 if (count != ocount) 1899 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); 1900 1901 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); 1902 if (written > 0) { 1903 loff_t end = pos + written; 1904 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { 1905 i_size_write(inode, end); 1906 mark_inode_dirty(inode); 1907 } 1908 *ppos = end; 1909 } 1910 1911 /* 1912 * Sync the fs metadata but not the minor inode changes and 1913 * of course not the data as we did direct DMA for the IO. 1914 * i_sem is held, which protects generic_osync_inode() from 1915 * livelocking. 1916 */ 1917 if (written >= 0 && file->f_flags & O_SYNC) 1918 generic_osync_inode(inode, mapping, OSYNC_METADATA); 1919 if (written == count && !is_sync_kiocb(iocb)) 1920 written = -EIOCBQUEUED; 1921 return written; 1922} 1923EXPORT_SYMBOL(generic_file_direct_write); 1924 1925ssize_t 1926generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, 1927 unsigned long nr_segs, loff_t pos, loff_t *ppos, 1928 size_t count, ssize_t written) 1929{ 1930 struct file *file = iocb->ki_filp; 1931 struct address_space * mapping = file->f_mapping; 1932 struct address_space_operations *a_ops = mapping->a_ops; 1933 struct inode *inode = mapping->host; 1934 long status = 0; 1935 struct page *page; 1936 struct page *cached_page = NULL; 1937 size_t bytes; 1938 struct pagevec lru_pvec; 1939 const struct iovec *cur_iov = iov; /* current iovec */ 1940 size_t iov_base = 0; /* offset in the current iovec */ 1941 char __user *buf; 1942 1943 pagevec_init(&lru_pvec, 0); 1944 1945 /* 1946 * handle partial DIO write. Adjust cur_iov if needed. 1947 */ 1948 if (likely(nr_segs == 1)) 1949 buf = iov->iov_base + written; 1950 else { 1951 filemap_set_next_iovec(&cur_iov, &iov_base, written); 1952 buf = iov->iov_base + iov_base; 1953 } 1954 1955 do { 1956 unsigned long index; 1957 unsigned long offset; 1958 size_t copied; 1959 1960 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1961 index = pos >> PAGE_CACHE_SHIFT; 1962 bytes = PAGE_CACHE_SIZE - offset; 1963 if (bytes > count) 1964 bytes = count; 1965 1966 /* 1967 * Bring in the user page that we will copy from _first_. 1968 * Otherwise there's a nasty deadlock on copying from the 1969 * same page as we're writing to, without it being marked 1970 * up-to-date. 1971 */ 1972 fault_in_pages_readable(buf, bytes); 1973 1974 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); 1975 if (!page) { 1976 status = -ENOMEM; 1977 break; 1978 } 1979 1980 status = a_ops->prepare_write(file, page, offset, offset+bytes); 1981 if (unlikely(status)) { 1982 loff_t isize = i_size_read(inode); 1983 /* 1984 * prepare_write() may have instantiated a few blocks 1985 * outside i_size. Trim these off again. 1986 */ 1987 unlock_page(page); 1988 page_cache_release(page); 1989 if (pos + bytes > isize) 1990 vmtruncate(inode, isize); 1991 break; 1992 } 1993 if (likely(nr_segs == 1)) 1994 copied = filemap_copy_from_user(page, offset, 1995 buf, bytes); 1996 else 1997 copied = filemap_copy_from_user_iovec(page, offset, 1998 cur_iov, iov_base, bytes); 1999 flush_dcache_page(page); 2000 status = a_ops->commit_write(file, page, offset, offset+bytes); 2001 if (likely(copied > 0)) { 2002 if (!status) 2003 status = copied; 2004 2005 if (status >= 0) { 2006 written += status; 2007 count -= status; 2008 pos += status; 2009 buf += status; 2010 if (unlikely(nr_segs > 1)) 2011 filemap_set_next_iovec(&cur_iov, 2012 &iov_base, status); 2013 } 2014 } 2015 if (unlikely(copied != bytes)) 2016 if (status >= 0) 2017 status = -EFAULT; 2018 unlock_page(page); 2019 mark_page_accessed(page); 2020 page_cache_release(page); 2021 if (status < 0) 2022 break; 2023 balance_dirty_pages_ratelimited(mapping); 2024 cond_resched(); 2025 } while (count); 2026 *ppos = pos; 2027 2028 if (cached_page) 2029 page_cache_release(cached_page); 2030 2031 /* 2032 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC 2033 */ 2034 if (likely(status >= 0)) { 2035 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2036 if (!a_ops->writepage || !is_sync_kiocb(iocb)) 2037 status = generic_osync_inode(inode, mapping, 2038 OSYNC_METADATA|OSYNC_DATA); 2039 } 2040 } 2041 2042 /* 2043 * If we get here for O_DIRECT writes then we must have fallen through 2044 * to buffered writes (block instantiation inside i_size). So we sync 2045 * the file data here, to try to honour O_DIRECT expectations. 2046 */ 2047 if (unlikely(file->f_flags & O_DIRECT) && written) 2048 status = filemap_write_and_wait(mapping); 2049 2050 pagevec_lru_add(&lru_pvec); 2051 return written ? written : status; 2052} 2053EXPORT_SYMBOL(generic_file_buffered_write); 2054 2055ssize_t 2056__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, 2057 unsigned long nr_segs, loff_t *ppos) 2058{ 2059 struct file *file = iocb->ki_filp; 2060 struct address_space * mapping = file->f_mapping; 2061 size_t ocount; /* original count */ 2062 size_t count; /* after file limit checks */ 2063 struct inode *inode = mapping->host; 2064 unsigned long seg; 2065 loff_t pos; 2066 ssize_t written; 2067 ssize_t err; 2068 2069 ocount = 0; 2070 for (seg = 0; seg < nr_segs; seg++) { 2071 const struct iovec *iv = &iov[seg]; 2072 2073 /* 2074 * If any segment has a negative length, or the cumulative 2075 * length ever wraps negative then return -EINVAL. 2076 */ 2077 ocount += iv->iov_len; 2078 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) 2079 return -EINVAL; 2080 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) 2081 continue; 2082 if (seg == 0) 2083 return -EFAULT; 2084 nr_segs = seg; 2085 ocount -= iv->iov_len; /* This segment is no good */ 2086 break; 2087 } 2088 2089 count = ocount; 2090 pos = *ppos; 2091 2092 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); 2093 2094 /* We can write back this queue in page reclaim */ 2095 current->backing_dev_info = mapping->backing_dev_info; 2096 written = 0; 2097 2098 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); 2099 if (err) 2100 goto out; 2101 2102 if (count == 0) 2103 goto out; 2104 2105 err = remove_suid(file->f_dentry); 2106 if (err) 2107 goto out; 2108 2109 inode_update_time(inode, 1); 2110 2111 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ 2112 if (unlikely(file->f_flags & O_DIRECT)) { 2113 written = generic_file_direct_write(iocb, iov, 2114 &nr_segs, pos, ppos, count, ocount); 2115 if (written < 0 || written == count) 2116 goto out; 2117 /* 2118 * direct-io write to a hole: fall through to buffered I/O 2119 * for completing the rest of the request. 2120 */ 2121 pos += written; 2122 count -= written; 2123 } 2124 2125 written = generic_file_buffered_write(iocb, iov, nr_segs, 2126 pos, ppos, count, written); 2127out: 2128 current->backing_dev_info = NULL; 2129 return written ? written : err; 2130} 2131EXPORT_SYMBOL(generic_file_aio_write_nolock); 2132 2133ssize_t 2134generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, 2135 unsigned long nr_segs, loff_t *ppos) 2136{ 2137 struct file *file = iocb->ki_filp; 2138 struct address_space *mapping = file->f_mapping; 2139 struct inode *inode = mapping->host; 2140 ssize_t ret; 2141 loff_t pos = *ppos; 2142 2143 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos); 2144 2145 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2146 int err; 2147 2148 err = sync_page_range_nolock(inode, mapping, pos, ret); 2149 if (err < 0) 2150 ret = err; 2151 } 2152 return ret; 2153} 2154 2155ssize_t 2156__generic_file_write_nolock(struct file *file, const struct iovec *iov, 2157 unsigned long nr_segs, loff_t *ppos) 2158{ 2159 struct kiocb kiocb; 2160 ssize_t ret; 2161 2162 init_sync_kiocb(&kiocb, file); 2163 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); 2164 if (ret == -EIOCBQUEUED) 2165 ret = wait_on_sync_kiocb(&kiocb); 2166 return ret; 2167} 2168 2169ssize_t 2170generic_file_write_nolock(struct file *file, const struct iovec *iov, 2171 unsigned long nr_segs, loff_t *ppos) 2172{ 2173 struct kiocb kiocb; 2174 ssize_t ret; 2175 2176 init_sync_kiocb(&kiocb, file); 2177 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); 2178 if (-EIOCBQUEUED == ret) 2179 ret = wait_on_sync_kiocb(&kiocb); 2180 return ret; 2181} 2182EXPORT_SYMBOL(generic_file_write_nolock); 2183 2184ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf, 2185 size_t count, loff_t pos) 2186{ 2187 struct file *file = iocb->ki_filp; 2188 struct address_space *mapping = file->f_mapping; 2189 struct inode *inode = mapping->host; 2190 ssize_t ret; 2191 struct iovec local_iov = { .iov_base = (void __user *)buf, 2192 .iov_len = count }; 2193 2194 BUG_ON(iocb->ki_pos != pos); 2195 2196 down(&inode->i_sem); 2197 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1, 2198 &iocb->ki_pos); 2199 up(&inode->i_sem); 2200 2201 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2202 ssize_t err; 2203 2204 err = sync_page_range(inode, mapping, pos, ret); 2205 if (err < 0) 2206 ret = err; 2207 } 2208 return ret; 2209} 2210EXPORT_SYMBOL(generic_file_aio_write); 2211 2212ssize_t generic_file_write(struct file *file, const char __user *buf, 2213 size_t count, loff_t *ppos) 2214{ 2215 struct address_space *mapping = file->f_mapping; 2216 struct inode *inode = mapping->host; 2217 ssize_t ret; 2218 struct iovec local_iov = { .iov_base = (void __user *)buf, 2219 .iov_len = count }; 2220 2221 down(&inode->i_sem); 2222 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos); 2223 up(&inode->i_sem); 2224 2225 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2226 ssize_t err; 2227 2228 err = sync_page_range(inode, mapping, *ppos - ret, ret); 2229 if (err < 0) 2230 ret = err; 2231 } 2232 return ret; 2233} 2234EXPORT_SYMBOL(generic_file_write); 2235 2236ssize_t generic_file_readv(struct file *filp, const struct iovec *iov, 2237 unsigned long nr_segs, loff_t *ppos) 2238{ 2239 struct kiocb kiocb; 2240 ssize_t ret; 2241 2242 init_sync_kiocb(&kiocb, filp); 2243 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos); 2244 if (-EIOCBQUEUED == ret) 2245 ret = wait_on_sync_kiocb(&kiocb); 2246 return ret; 2247} 2248EXPORT_SYMBOL(generic_file_readv); 2249 2250ssize_t generic_file_writev(struct file *file, const struct iovec *iov, 2251 unsigned long nr_segs, loff_t *ppos) 2252{ 2253 struct address_space *mapping = file->f_mapping; 2254 struct inode *inode = mapping->host; 2255 ssize_t ret; 2256 2257 down(&inode->i_sem); 2258 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos); 2259 up(&inode->i_sem); 2260 2261 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2262 int err; 2263 2264 err = sync_page_range(inode, mapping, *ppos - ret, ret); 2265 if (err < 0) 2266 ret = err; 2267 } 2268 return ret; 2269} 2270EXPORT_SYMBOL(generic_file_writev); 2271 2272/* 2273 * Called under i_sem for writes to S_ISREG files. Returns -EIO if something 2274 * went wrong during pagecache shootdown. 2275 */ 2276ssize_t 2277generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, 2278 loff_t offset, unsigned long nr_segs) 2279{ 2280 struct file *file = iocb->ki_filp; 2281 struct address_space *mapping = file->f_mapping; 2282 ssize_t retval; 2283 size_t write_len = 0; 2284 2285 /* 2286 * If it's a write, unmap all mmappings of the file up-front. This 2287 * will cause any pte dirty bits to be propagated into the pageframes 2288 * for the subsequent filemap_write_and_wait(). 2289 */ 2290 if (rw == WRITE) { 2291 write_len = iov_length(iov, nr_segs); 2292 if (mapping_mapped(mapping)) 2293 unmap_mapping_range(mapping, offset, write_len, 0); 2294 } 2295 2296 retval = filemap_write_and_wait(mapping); 2297 if (retval == 0) { 2298 retval = mapping->a_ops->direct_IO(rw, iocb, iov, 2299 offset, nr_segs); 2300 if (rw == WRITE && mapping->nrpages) { 2301 pgoff_t end = (offset + write_len - 1) 2302 >> PAGE_CACHE_SHIFT; 2303 int err = invalidate_inode_pages2_range(mapping, 2304 offset >> PAGE_CACHE_SHIFT, end); 2305 if (err) 2306 retval = err; 2307 } 2308 } 2309 return retval; 2310} 2311EXPORT_SYMBOL_GPL(generic_file_direct_IO); 2312