filemap.c revision c25ec8f5684cb3c5dde6a67c1bbc33a449eefbe2
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/capability.h> 19#include <linux/kernel_stat.h> 20#include <linux/mm.h> 21#include <linux/swap.h> 22#include <linux/mman.h> 23#include <linux/pagemap.h> 24#include <linux/file.h> 25#include <linux/uio.h> 26#include <linux/hash.h> 27#include <linux/writeback.h> 28#include <linux/pagevec.h> 29#include <linux/blkdev.h> 30#include <linux/security.h> 31#include <linux/syscalls.h> 32#include "filemap.h" 33/* 34 * FIXME: remove all knowledge of the buffer layer from the core VM 35 */ 36#include <linux/buffer_head.h> /* for generic_osync_inode */ 37 38#include <asm/uaccess.h> 39#include <asm/mman.h> 40 41static ssize_t 42generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, 43 loff_t offset, unsigned long nr_segs); 44 45/* 46 * Shared mappings implemented 30.11.1994. It's not fully working yet, 47 * though. 48 * 49 * Shared mappings now work. 15.8.1995 Bruno. 50 * 51 * finished 'unifying' the page and buffer cache and SMP-threaded the 52 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> 53 * 54 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> 55 */ 56 57/* 58 * Lock ordering: 59 * 60 * ->i_mmap_lock (vmtruncate) 61 * ->private_lock (__free_pte->__set_page_dirty_buffers) 62 * ->swap_lock (exclusive_swap_page, others) 63 * ->mapping->tree_lock 64 * 65 * ->i_mutex 66 * ->i_mmap_lock (truncate->unmap_mapping_range) 67 * 68 * ->mmap_sem 69 * ->i_mmap_lock 70 * ->page_table_lock or pte_lock (various, mainly in memory.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_mutex (msync) 78 * 79 * ->i_mutex 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 or pte_lock (anon_vma_prepare and various) 91 * 92 * ->page_table_lock or pte_lock 93 * ->swap_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 * ->zone.lru_lock (check_pte_range->isolate_lru_page) 98 * ->private_lock (page_remove_rmap->set_page_dirty) 99 * ->tree_lock (page_remove_rmap->set_page_dirty) 100 * ->inode_lock (page_remove_rmap->set_page_dirty) 101 * ->inode_lock (zap_pte_range->set_page_dirty) 102 * ->private_lock (zap_pte_range->__set_page_dirty_buffers) 103 * 104 * ->task->proc_lock 105 * ->dcache_lock (proc_pid_lookup) 106 */ 107 108/* 109 * Remove a page from the page cache and free it. Caller has to make 110 * sure the page is locked and that nobody else uses it - or that usage 111 * is safe. The caller must hold a write_lock on the mapping's tree_lock. 112 */ 113void __remove_from_page_cache(struct page *page) 114{ 115 struct address_space *mapping = page->mapping; 116 117 radix_tree_delete(&mapping->page_tree, page->index); 118 page->mapping = NULL; 119 mapping->nrpages--; 120 pagecache_acct(-1); 121} 122 123void remove_from_page_cache(struct page *page) 124{ 125 struct address_space *mapping = page->mapping; 126 127 BUG_ON(!PageLocked(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((unsigned long *)word, struct page, flags); 140 141 /* 142 * page_mapping() is being called without PG_locked held. 143 * Some knowledge of the state and use of the page is used to 144 * reduce the requirements down to a memory barrier. 145 * The danger here is of a stale page_mapping() return value 146 * indicating a struct address_space different from the one it's 147 * associated with when it is associated with one. 148 * After smp_mb(), it's either the correct page_mapping() for 149 * the page, or an old page_mapping() and the page's own 150 * page_mapping() has gone NULL. 151 * The ->sync_page() address_space operation must tolerate 152 * page_mapping() going NULL. By an amazing coincidence, 153 * this comes about because none of the users of the page 154 * in the ->sync_page() methods make essential use of the 155 * page_mapping(), merely passing the page down to the backing 156 * device's unplug functions when it's non-NULL, which in turn 157 * ignore it for all cases but swap, where only page_private(page) is 158 * of interest. When page_mapping() does go NULL, the entire 159 * call stack gracefully ignores the page and returns. 160 * -- wli 161 */ 162 smp_mb(); 163 mapping = page_mapping(page); 164 if (mapping && mapping->a_ops && mapping->a_ops->sync_page) 165 mapping->a_ops->sync_page(page); 166 io_schedule(); 167 return 0; 168} 169 170/** 171 * filemap_fdatawrite_range - start writeback against all of a mapping's 172 * dirty pages that lie within the byte offsets <start, end> 173 * @mapping: address space structure to write 174 * @start: offset in bytes where the range starts 175 * @end: offset in bytes where the range ends 176 * @sync_mode: enable synchronous operation 177 * 178 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as 179 * opposed to a regular memory * cleansing writeback. The difference between 180 * these two operations is that if a dirty page/buffer is encountered, it must 181 * be waited upon, and not just skipped over. 182 */ 183static int __filemap_fdatawrite_range(struct address_space *mapping, 184 loff_t start, loff_t end, int sync_mode) 185{ 186 int ret; 187 struct writeback_control wbc = { 188 .sync_mode = sync_mode, 189 .nr_to_write = mapping->nrpages * 2, 190 .start = start, 191 .end = end, 192 }; 193 194 if (!mapping_cap_writeback_dirty(mapping)) 195 return 0; 196 197 ret = do_writepages(mapping, &wbc); 198 return ret; 199} 200 201static inline int __filemap_fdatawrite(struct address_space *mapping, 202 int sync_mode) 203{ 204 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode); 205} 206 207int filemap_fdatawrite(struct address_space *mapping) 208{ 209 return __filemap_fdatawrite(mapping, WB_SYNC_ALL); 210} 211EXPORT_SYMBOL(filemap_fdatawrite); 212 213static int filemap_fdatawrite_range(struct address_space *mapping, 214 loff_t start, loff_t end) 215{ 216 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); 217} 218 219/* 220 * This is a mostly non-blocking flush. Not suitable for data-integrity 221 * purposes - I/O may not be started against all dirty pages. 222 */ 223int filemap_flush(struct address_space *mapping) 224{ 225 return __filemap_fdatawrite(mapping, WB_SYNC_NONE); 226} 227EXPORT_SYMBOL(filemap_flush); 228 229/* 230 * Wait for writeback to complete against pages indexed by start->end 231 * inclusive 232 */ 233static int wait_on_page_writeback_range(struct address_space *mapping, 234 pgoff_t start, pgoff_t end) 235{ 236 struct pagevec pvec; 237 int nr_pages; 238 int ret = 0; 239 pgoff_t index; 240 241 if (end < start) 242 return 0; 243 244 pagevec_init(&pvec, 0); 245 index = start; 246 while ((index <= end) && 247 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, 248 PAGECACHE_TAG_WRITEBACK, 249 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { 250 unsigned i; 251 252 for (i = 0; i < nr_pages; i++) { 253 struct page *page = pvec.pages[i]; 254 255 /* until radix tree lookup accepts end_index */ 256 if (page->index > end) 257 continue; 258 259 wait_on_page_writeback(page); 260 if (PageError(page)) 261 ret = -EIO; 262 } 263 pagevec_release(&pvec); 264 cond_resched(); 265 } 266 267 /* Check for outstanding write errors */ 268 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) 269 ret = -ENOSPC; 270 if (test_and_clear_bit(AS_EIO, &mapping->flags)) 271 ret = -EIO; 272 273 return ret; 274} 275 276/* 277 * Write and wait upon all the pages in the passed range. This is a "data 278 * integrity" operation. It waits upon in-flight writeout before starting and 279 * waiting upon new writeout. If there was an IO error, return it. 280 * 281 * We need to re-take i_mutex during the generic_osync_inode list walk because 282 * it is otherwise livelockable. 283 */ 284int sync_page_range(struct inode *inode, struct address_space *mapping, 285 loff_t pos, loff_t count) 286{ 287 pgoff_t start = pos >> PAGE_CACHE_SHIFT; 288 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; 289 int ret; 290 291 if (!mapping_cap_writeback_dirty(mapping) || !count) 292 return 0; 293 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); 294 if (ret == 0) { 295 mutex_lock(&inode->i_mutex); 296 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); 297 mutex_unlock(&inode->i_mutex); 298 } 299 if (ret == 0) 300 ret = wait_on_page_writeback_range(mapping, start, end); 301 return ret; 302} 303EXPORT_SYMBOL(sync_page_range); 304 305/* 306 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea 307 * as it forces O_SYNC writers to different parts of the same file 308 * to be serialised right until io completion. 309 */ 310int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, 311 loff_t pos, loff_t count) 312{ 313 pgoff_t start = pos >> PAGE_CACHE_SHIFT; 314 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; 315 int ret; 316 317 if (!mapping_cap_writeback_dirty(mapping) || !count) 318 return 0; 319 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); 320 if (ret == 0) 321 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); 322 if (ret == 0) 323 ret = wait_on_page_writeback_range(mapping, start, end); 324 return ret; 325} 326EXPORT_SYMBOL(sync_page_range_nolock); 327 328/** 329 * filemap_fdatawait - walk the list of under-writeback pages of the given 330 * address space and wait for all of them. 331 * 332 * @mapping: address space structure to wait for 333 */ 334int filemap_fdatawait(struct address_space *mapping) 335{ 336 loff_t i_size = i_size_read(mapping->host); 337 338 if (i_size == 0) 339 return 0; 340 341 return wait_on_page_writeback_range(mapping, 0, 342 (i_size - 1) >> PAGE_CACHE_SHIFT); 343} 344EXPORT_SYMBOL(filemap_fdatawait); 345 346int filemap_write_and_wait(struct address_space *mapping) 347{ 348 int err = 0; 349 350 if (mapping->nrpages) { 351 err = filemap_fdatawrite(mapping); 352 /* 353 * Even if the above returned error, the pages may be 354 * written partially (e.g. -ENOSPC), so we wait for it. 355 * But the -EIO is special case, it may indicate the worst 356 * thing (e.g. bug) happened, so we avoid waiting for it. 357 */ 358 if (err != -EIO) { 359 int err2 = filemap_fdatawait(mapping); 360 if (!err) 361 err = err2; 362 } 363 } 364 return err; 365} 366EXPORT_SYMBOL(filemap_write_and_wait); 367 368int filemap_write_and_wait_range(struct address_space *mapping, 369 loff_t lstart, loff_t lend) 370{ 371 int err = 0; 372 373 if (mapping->nrpages) { 374 err = __filemap_fdatawrite_range(mapping, lstart, lend, 375 WB_SYNC_ALL); 376 /* See comment of filemap_write_and_wait() */ 377 if (err != -EIO) { 378 int err2 = wait_on_page_writeback_range(mapping, 379 lstart >> PAGE_CACHE_SHIFT, 380 lend >> PAGE_CACHE_SHIFT); 381 if (!err) 382 err = err2; 383 } 384 } 385 return err; 386} 387 388/* 389 * This function is used to add newly allocated pagecache pages: 390 * the page is new, so we can just run SetPageLocked() against it. 391 * The other page state flags were set by rmqueue(). 392 * 393 * This function does not add the page to the LRU. The caller must do that. 394 */ 395int add_to_page_cache(struct page *page, struct address_space *mapping, 396 pgoff_t offset, gfp_t gfp_mask) 397{ 398 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); 399 400 if (error == 0) { 401 write_lock_irq(&mapping->tree_lock); 402 error = radix_tree_insert(&mapping->page_tree, offset, page); 403 if (!error) { 404 page_cache_get(page); 405 SetPageLocked(page); 406 page->mapping = mapping; 407 page->index = offset; 408 mapping->nrpages++; 409 pagecache_acct(1); 410 } 411 write_unlock_irq(&mapping->tree_lock); 412 radix_tree_preload_end(); 413 } 414 return error; 415} 416 417EXPORT_SYMBOL(add_to_page_cache); 418 419int add_to_page_cache_lru(struct page *page, struct address_space *mapping, 420 pgoff_t offset, gfp_t gfp_mask) 421{ 422 int ret = add_to_page_cache(page, mapping, offset, gfp_mask); 423 if (ret == 0) 424 lru_cache_add(page); 425 return ret; 426} 427 428/* 429 * In order to wait for pages to become available there must be 430 * waitqueues associated with pages. By using a hash table of 431 * waitqueues where the bucket discipline is to maintain all 432 * waiters on the same queue and wake all when any of the pages 433 * become available, and for the woken contexts to check to be 434 * sure the appropriate page became available, this saves space 435 * at a cost of "thundering herd" phenomena during rare hash 436 * collisions. 437 */ 438static wait_queue_head_t *page_waitqueue(struct page *page) 439{ 440 const struct zone *zone = page_zone(page); 441 442 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; 443} 444 445static inline void wake_up_page(struct page *page, int bit) 446{ 447 __wake_up_bit(page_waitqueue(page), &page->flags, bit); 448} 449 450void fastcall wait_on_page_bit(struct page *page, int bit_nr) 451{ 452 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); 453 454 if (test_bit(bit_nr, &page->flags)) 455 __wait_on_bit(page_waitqueue(page), &wait, sync_page, 456 TASK_UNINTERRUPTIBLE); 457} 458EXPORT_SYMBOL(wait_on_page_bit); 459 460/** 461 * unlock_page() - unlock a locked page 462 * 463 * @page: the page 464 * 465 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). 466 * Also wakes sleepers in wait_on_page_writeback() because the wakeup 467 * mechananism between PageLocked pages and PageWriteback pages is shared. 468 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. 469 * 470 * The first mb is necessary to safely close the critical section opened by the 471 * TestSetPageLocked(), the second mb is necessary to enforce ordering between 472 * the clear_bit and the read of the waitqueue (to avoid SMP races with a 473 * parallel wait_on_page_locked()). 474 */ 475void fastcall unlock_page(struct page *page) 476{ 477 smp_mb__before_clear_bit(); 478 if (!TestClearPageLocked(page)) 479 BUG(); 480 smp_mb__after_clear_bit(); 481 wake_up_page(page, PG_locked); 482} 483EXPORT_SYMBOL(unlock_page); 484 485/* 486 * End writeback against a page. 487 */ 488void end_page_writeback(struct page *page) 489{ 490 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { 491 if (!test_clear_page_writeback(page)) 492 BUG(); 493 } 494 smp_mb__after_clear_bit(); 495 wake_up_page(page, PG_writeback); 496} 497EXPORT_SYMBOL(end_page_writeback); 498 499/* 500 * Get a lock on the page, assuming we need to sleep to get it. 501 * 502 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some 503 * random driver's requestfn sets TASK_RUNNING, we could busywait. However 504 * chances are that on the second loop, the block layer's plug list is empty, 505 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. 506 */ 507void fastcall __lock_page(struct page *page) 508{ 509 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); 510 511 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, 512 TASK_UNINTERRUPTIBLE); 513} 514EXPORT_SYMBOL(__lock_page); 515 516/* 517 * a rather lightweight function, finding and getting a reference to a 518 * hashed page atomically. 519 */ 520struct page * find_get_page(struct address_space *mapping, unsigned long offset) 521{ 522 struct page *page; 523 524 read_lock_irq(&mapping->tree_lock); 525 page = radix_tree_lookup(&mapping->page_tree, offset); 526 if (page) 527 page_cache_get(page); 528 read_unlock_irq(&mapping->tree_lock); 529 return page; 530} 531 532EXPORT_SYMBOL(find_get_page); 533 534/* 535 * Same as above, but trylock it instead of incrementing the count. 536 */ 537struct page *find_trylock_page(struct address_space *mapping, unsigned long offset) 538{ 539 struct page *page; 540 541 read_lock_irq(&mapping->tree_lock); 542 page = radix_tree_lookup(&mapping->page_tree, offset); 543 if (page && TestSetPageLocked(page)) 544 page = NULL; 545 read_unlock_irq(&mapping->tree_lock); 546 return page; 547} 548 549EXPORT_SYMBOL(find_trylock_page); 550 551/** 552 * find_lock_page - locate, pin and lock a pagecache page 553 * 554 * @mapping: the address_space to search 555 * @offset: the page index 556 * 557 * Locates the desired pagecache page, locks it, increments its reference 558 * count and returns its address. 559 * 560 * Returns zero if the page was not present. find_lock_page() may sleep. 561 */ 562struct page *find_lock_page(struct address_space *mapping, 563 unsigned long offset) 564{ 565 struct page *page; 566 567 read_lock_irq(&mapping->tree_lock); 568repeat: 569 page = radix_tree_lookup(&mapping->page_tree, offset); 570 if (page) { 571 page_cache_get(page); 572 if (TestSetPageLocked(page)) { 573 read_unlock_irq(&mapping->tree_lock); 574 __lock_page(page); 575 read_lock_irq(&mapping->tree_lock); 576 577 /* Has the page been truncated while we slept? */ 578 if (unlikely(page->mapping != mapping || 579 page->index != offset)) { 580 unlock_page(page); 581 page_cache_release(page); 582 goto repeat; 583 } 584 } 585 } 586 read_unlock_irq(&mapping->tree_lock); 587 return page; 588} 589 590EXPORT_SYMBOL(find_lock_page); 591 592/** 593 * find_or_create_page - locate or add a pagecache page 594 * 595 * @mapping: the page's address_space 596 * @index: the page's index into the mapping 597 * @gfp_mask: page allocation mode 598 * 599 * Locates a page in the pagecache. If the page is not present, a new page 600 * is allocated using @gfp_mask and is added to the pagecache and to the VM's 601 * LRU list. The returned page is locked and has its reference count 602 * incremented. 603 * 604 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic 605 * allocation! 606 * 607 * find_or_create_page() returns the desired page's address, or zero on 608 * memory exhaustion. 609 */ 610struct page *find_or_create_page(struct address_space *mapping, 611 unsigned long index, gfp_t gfp_mask) 612{ 613 struct page *page, *cached_page = NULL; 614 int err; 615repeat: 616 page = find_lock_page(mapping, index); 617 if (!page) { 618 if (!cached_page) { 619 cached_page = alloc_page(gfp_mask); 620 if (!cached_page) 621 return NULL; 622 } 623 err = add_to_page_cache_lru(cached_page, mapping, 624 index, gfp_mask); 625 if (!err) { 626 page = cached_page; 627 cached_page = NULL; 628 } else if (err == -EEXIST) 629 goto repeat; 630 } 631 if (cached_page) 632 page_cache_release(cached_page); 633 return page; 634} 635 636EXPORT_SYMBOL(find_or_create_page); 637 638/** 639 * find_get_pages - gang pagecache lookup 640 * @mapping: The address_space to search 641 * @start: The starting page index 642 * @nr_pages: The maximum number of pages 643 * @pages: Where the resulting pages are placed 644 * 645 * find_get_pages() will search for and return a group of up to 646 * @nr_pages pages in the mapping. The pages are placed at @pages. 647 * find_get_pages() takes a reference against the returned pages. 648 * 649 * The search returns a group of mapping-contiguous pages with ascending 650 * indexes. There may be holes in the indices due to not-present pages. 651 * 652 * find_get_pages() returns the number of pages which were found. 653 */ 654unsigned find_get_pages(struct address_space *mapping, pgoff_t start, 655 unsigned int nr_pages, struct page **pages) 656{ 657 unsigned int i; 658 unsigned int ret; 659 660 read_lock_irq(&mapping->tree_lock); 661 ret = radix_tree_gang_lookup(&mapping->page_tree, 662 (void **)pages, start, nr_pages); 663 for (i = 0; i < ret; i++) 664 page_cache_get(pages[i]); 665 read_unlock_irq(&mapping->tree_lock); 666 return ret; 667} 668 669/* 670 * Like find_get_pages, except we only return pages which are tagged with 671 * `tag'. We update *index to index the next page for the traversal. 672 */ 673unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, 674 int tag, unsigned int nr_pages, struct page **pages) 675{ 676 unsigned int i; 677 unsigned int ret; 678 679 read_lock_irq(&mapping->tree_lock); 680 ret = radix_tree_gang_lookup_tag(&mapping->page_tree, 681 (void **)pages, *index, nr_pages, tag); 682 for (i = 0; i < ret; i++) 683 page_cache_get(pages[i]); 684 if (ret) 685 *index = pages[ret - 1]->index + 1; 686 read_unlock_irq(&mapping->tree_lock); 687 return ret; 688} 689 690/* 691 * Same as grab_cache_page, but do not wait if the page is unavailable. 692 * This is intended for speculative data generators, where the data can 693 * be regenerated if the page couldn't be grabbed. This routine should 694 * be safe to call while holding the lock for another page. 695 * 696 * Clear __GFP_FS when allocating the page to avoid recursion into the fs 697 * and deadlock against the caller's locked page. 698 */ 699struct page * 700grab_cache_page_nowait(struct address_space *mapping, unsigned long index) 701{ 702 struct page *page = find_get_page(mapping, index); 703 gfp_t gfp_mask; 704 705 if (page) { 706 if (!TestSetPageLocked(page)) 707 return page; 708 page_cache_release(page); 709 return NULL; 710 } 711 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS; 712 page = alloc_pages(gfp_mask, 0); 713 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) { 714 page_cache_release(page); 715 page = NULL; 716 } 717 return page; 718} 719 720EXPORT_SYMBOL(grab_cache_page_nowait); 721 722/* 723 * This is a generic file read routine, and uses the 724 * mapping->a_ops->readpage() function for the actual low-level 725 * stuff. 726 * 727 * This is really ugly. But the goto's actually try to clarify some 728 * of the logic when it comes to error handling etc. 729 * 730 * Note the struct file* is only passed for the use of readpage. It may be 731 * NULL. 732 */ 733void do_generic_mapping_read(struct address_space *mapping, 734 struct file_ra_state *_ra, 735 struct file *filp, 736 loff_t *ppos, 737 read_descriptor_t *desc, 738 read_actor_t actor) 739{ 740 struct inode *inode = mapping->host; 741 unsigned long index; 742 unsigned long end_index; 743 unsigned long offset; 744 unsigned long last_index; 745 unsigned long next_index; 746 unsigned long prev_index; 747 loff_t isize; 748 struct page *cached_page; 749 int error; 750 struct file_ra_state ra = *_ra; 751 752 cached_page = NULL; 753 index = *ppos >> PAGE_CACHE_SHIFT; 754 next_index = index; 755 prev_index = ra.prev_page; 756 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; 757 offset = *ppos & ~PAGE_CACHE_MASK; 758 759 isize = i_size_read(inode); 760 if (!isize) 761 goto out; 762 763 end_index = (isize - 1) >> PAGE_CACHE_SHIFT; 764 for (;;) { 765 struct page *page; 766 unsigned long nr, ret; 767 768 /* nr is the maximum number of bytes to copy from this page */ 769 nr = PAGE_CACHE_SIZE; 770 if (index >= end_index) { 771 if (index > end_index) 772 goto out; 773 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; 774 if (nr <= offset) { 775 goto out; 776 } 777 } 778 nr = nr - offset; 779 780 cond_resched(); 781 if (index == next_index) 782 next_index = page_cache_readahead(mapping, &ra, filp, 783 index, last_index - index); 784 785find_page: 786 page = find_get_page(mapping, index); 787 if (unlikely(page == NULL)) { 788 handle_ra_miss(mapping, &ra, index); 789 goto no_cached_page; 790 } 791 if (!PageUptodate(page)) 792 goto page_not_up_to_date; 793page_ok: 794 795 /* If users can be writing to this page using arbitrary 796 * virtual addresses, take care about potential aliasing 797 * before reading the page on the kernel side. 798 */ 799 if (mapping_writably_mapped(mapping)) 800 flush_dcache_page(page); 801 802 /* 803 * When (part of) the same page is read multiple times 804 * in succession, only mark it as accessed the first time. 805 */ 806 if (prev_index != index) 807 mark_page_accessed(page); 808 prev_index = index; 809 810 /* 811 * Ok, we have the page, and it's up-to-date, so 812 * now we can copy it to user space... 813 * 814 * The actor routine returns how many bytes were actually used.. 815 * NOTE! This may not be the same as how much of a user buffer 816 * we filled up (we may be padding etc), so we can only update 817 * "pos" here (the actor routine has to update the user buffer 818 * pointers and the remaining count). 819 */ 820 ret = actor(desc, page, offset, nr); 821 offset += ret; 822 index += offset >> PAGE_CACHE_SHIFT; 823 offset &= ~PAGE_CACHE_MASK; 824 825 page_cache_release(page); 826 if (ret == nr && desc->count) 827 continue; 828 goto out; 829 830page_not_up_to_date: 831 /* Get exclusive access to the page ... */ 832 lock_page(page); 833 834 /* Did it get unhashed before we got the lock? */ 835 if (!page->mapping) { 836 unlock_page(page); 837 page_cache_release(page); 838 continue; 839 } 840 841 /* Did somebody else fill it already? */ 842 if (PageUptodate(page)) { 843 unlock_page(page); 844 goto page_ok; 845 } 846 847readpage: 848 /* Start the actual read. The read will unlock the page. */ 849 error = mapping->a_ops->readpage(filp, page); 850 851 if (unlikely(error)) { 852 if (error == AOP_TRUNCATED_PAGE) { 853 page_cache_release(page); 854 goto find_page; 855 } 856 goto readpage_error; 857 } 858 859 if (!PageUptodate(page)) { 860 lock_page(page); 861 if (!PageUptodate(page)) { 862 if (page->mapping == NULL) { 863 /* 864 * invalidate_inode_pages got it 865 */ 866 unlock_page(page); 867 page_cache_release(page); 868 goto find_page; 869 } 870 unlock_page(page); 871 error = -EIO; 872 goto readpage_error; 873 } 874 unlock_page(page); 875 } 876 877 /* 878 * i_size must be checked after we have done ->readpage. 879 * 880 * Checking i_size after the readpage allows us to calculate 881 * the correct value for "nr", which means the zero-filled 882 * part of the page is not copied back to userspace (unless 883 * another truncate extends the file - this is desired though). 884 */ 885 isize = i_size_read(inode); 886 end_index = (isize - 1) >> PAGE_CACHE_SHIFT; 887 if (unlikely(!isize || index > end_index)) { 888 page_cache_release(page); 889 goto out; 890 } 891 892 /* nr is the maximum number of bytes to copy from this page */ 893 nr = PAGE_CACHE_SIZE; 894 if (index == end_index) { 895 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; 896 if (nr <= offset) { 897 page_cache_release(page); 898 goto out; 899 } 900 } 901 nr = nr - offset; 902 goto page_ok; 903 904readpage_error: 905 /* UHHUH! A synchronous read error occurred. Report it */ 906 desc->error = error; 907 page_cache_release(page); 908 goto out; 909 910no_cached_page: 911 /* 912 * Ok, it wasn't cached, so we need to create a new 913 * page.. 914 */ 915 if (!cached_page) { 916 cached_page = page_cache_alloc_cold(mapping); 917 if (!cached_page) { 918 desc->error = -ENOMEM; 919 goto out; 920 } 921 } 922 error = add_to_page_cache_lru(cached_page, mapping, 923 index, GFP_KERNEL); 924 if (error) { 925 if (error == -EEXIST) 926 goto find_page; 927 desc->error = error; 928 goto out; 929 } 930 page = cached_page; 931 cached_page = NULL; 932 goto readpage; 933 } 934 935out: 936 *_ra = ra; 937 938 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 939 if (cached_page) 940 page_cache_release(cached_page); 941 if (filp) 942 file_accessed(filp); 943} 944 945EXPORT_SYMBOL(do_generic_mapping_read); 946 947int file_read_actor(read_descriptor_t *desc, struct page *page, 948 unsigned long offset, unsigned long size) 949{ 950 char *kaddr; 951 unsigned long left, count = desc->count; 952 953 if (size > count) 954 size = count; 955 956 /* 957 * Faults on the destination of a read are common, so do it before 958 * taking the kmap. 959 */ 960 if (!fault_in_pages_writeable(desc->arg.buf, size)) { 961 kaddr = kmap_atomic(page, KM_USER0); 962 left = __copy_to_user_inatomic(desc->arg.buf, 963 kaddr + offset, size); 964 kunmap_atomic(kaddr, KM_USER0); 965 if (left == 0) 966 goto success; 967 } 968 969 /* Do it the slow way */ 970 kaddr = kmap(page); 971 left = __copy_to_user(desc->arg.buf, kaddr + offset, size); 972 kunmap(page); 973 974 if (left) { 975 size -= left; 976 desc->error = -EFAULT; 977 } 978success: 979 desc->count = count - size; 980 desc->written += size; 981 desc->arg.buf += size; 982 return size; 983} 984EXPORT_SYMBOL(file_read_actor); 985 986/* 987 * This is the "read()" routine for all filesystems 988 * that can use the page cache directly. 989 */ 990ssize_t 991__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, 992 unsigned long nr_segs, loff_t *ppos) 993{ 994 struct file *filp = iocb->ki_filp; 995 ssize_t retval; 996 unsigned long seg; 997 size_t count; 998 999 count = 0; 1000 for (seg = 0; seg < nr_segs; seg++) { 1001 const struct iovec *iv = &iov[seg]; 1002 1003 /* 1004 * If any segment has a negative length, or the cumulative 1005 * length ever wraps negative then return -EINVAL. 1006 */ 1007 count += iv->iov_len; 1008 if (unlikely((ssize_t)(count|iv->iov_len) < 0)) 1009 return -EINVAL; 1010 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) 1011 continue; 1012 if (seg == 0) 1013 return -EFAULT; 1014 nr_segs = seg; 1015 count -= iv->iov_len; /* This segment is no good */ 1016 break; 1017 } 1018 1019 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ 1020 if (filp->f_flags & O_DIRECT) { 1021 loff_t pos = *ppos, size; 1022 struct address_space *mapping; 1023 struct inode *inode; 1024 1025 mapping = filp->f_mapping; 1026 inode = mapping->host; 1027 retval = 0; 1028 if (!count) 1029 goto out; /* skip atime */ 1030 size = i_size_read(inode); 1031 if (pos < size) { 1032 retval = generic_file_direct_IO(READ, iocb, 1033 iov, pos, nr_segs); 1034 if (retval > 0 && !is_sync_kiocb(iocb)) 1035 retval = -EIOCBQUEUED; 1036 if (retval > 0) 1037 *ppos = pos + retval; 1038 } 1039 file_accessed(filp); 1040 goto out; 1041 } 1042 1043 retval = 0; 1044 if (count) { 1045 for (seg = 0; seg < nr_segs; seg++) { 1046 read_descriptor_t desc; 1047 1048 desc.written = 0; 1049 desc.arg.buf = iov[seg].iov_base; 1050 desc.count = iov[seg].iov_len; 1051 if (desc.count == 0) 1052 continue; 1053 desc.error = 0; 1054 do_generic_file_read(filp,ppos,&desc,file_read_actor); 1055 retval += desc.written; 1056 if (desc.error) { 1057 retval = retval ?: desc.error; 1058 break; 1059 } 1060 } 1061 } 1062out: 1063 return retval; 1064} 1065 1066EXPORT_SYMBOL(__generic_file_aio_read); 1067 1068ssize_t 1069generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) 1070{ 1071 struct iovec local_iov = { .iov_base = buf, .iov_len = count }; 1072 1073 BUG_ON(iocb->ki_pos != pos); 1074 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); 1075} 1076 1077EXPORT_SYMBOL(generic_file_aio_read); 1078 1079ssize_t 1080generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1081{ 1082 struct iovec local_iov = { .iov_base = buf, .iov_len = count }; 1083 struct kiocb kiocb; 1084 ssize_t ret; 1085 1086 init_sync_kiocb(&kiocb, filp); 1087 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); 1088 if (-EIOCBQUEUED == ret) 1089 ret = wait_on_sync_kiocb(&kiocb); 1090 return ret; 1091} 1092 1093EXPORT_SYMBOL(generic_file_read); 1094 1095int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) 1096{ 1097 ssize_t written; 1098 unsigned long count = desc->count; 1099 struct file *file = desc->arg.data; 1100 1101 if (size > count) 1102 size = count; 1103 1104 written = file->f_op->sendpage(file, page, offset, 1105 size, &file->f_pos, size<count); 1106 if (written < 0) { 1107 desc->error = written; 1108 written = 0; 1109 } 1110 desc->count = count - written; 1111 desc->written += written; 1112 return written; 1113} 1114 1115ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, 1116 size_t count, read_actor_t actor, void *target) 1117{ 1118 read_descriptor_t desc; 1119 1120 if (!count) 1121 return 0; 1122 1123 desc.written = 0; 1124 desc.count = count; 1125 desc.arg.data = target; 1126 desc.error = 0; 1127 1128 do_generic_file_read(in_file, ppos, &desc, actor); 1129 if (desc.written) 1130 return desc.written; 1131 return desc.error; 1132} 1133 1134EXPORT_SYMBOL(generic_file_sendfile); 1135 1136static ssize_t 1137do_readahead(struct address_space *mapping, struct file *filp, 1138 unsigned long index, unsigned long nr) 1139{ 1140 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) 1141 return -EINVAL; 1142 1143 force_page_cache_readahead(mapping, filp, index, 1144 max_sane_readahead(nr)); 1145 return 0; 1146} 1147 1148asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) 1149{ 1150 ssize_t ret; 1151 struct file *file; 1152 1153 ret = -EBADF; 1154 file = fget(fd); 1155 if (file) { 1156 if (file->f_mode & FMODE_READ) { 1157 struct address_space *mapping = file->f_mapping; 1158 unsigned long start = offset >> PAGE_CACHE_SHIFT; 1159 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT; 1160 unsigned long len = end - start + 1; 1161 ret = do_readahead(mapping, file, start, len); 1162 } 1163 fput(file); 1164 } 1165 return ret; 1166} 1167 1168#ifdef CONFIG_MMU 1169/* 1170 * This adds the requested page to the page cache if it isn't already there, 1171 * and schedules an I/O to read in its contents from disk. 1172 */ 1173static int FASTCALL(page_cache_read(struct file * file, unsigned long offset)); 1174static int fastcall page_cache_read(struct file * file, unsigned long offset) 1175{ 1176 struct address_space *mapping = file->f_mapping; 1177 struct page *page; 1178 int ret; 1179 1180 do { 1181 page = page_cache_alloc_cold(mapping); 1182 if (!page) 1183 return -ENOMEM; 1184 1185 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); 1186 if (ret == 0) 1187 ret = mapping->a_ops->readpage(file, page); 1188 else if (ret == -EEXIST) 1189 ret = 0; /* losing race to add is OK */ 1190 1191 page_cache_release(page); 1192 1193 } while (ret == AOP_TRUNCATED_PAGE); 1194 1195 return ret; 1196} 1197 1198#define MMAP_LOTSAMISS (100) 1199 1200/* 1201 * filemap_nopage() is invoked via the vma operations vector for a 1202 * mapped memory region to read in file data during a page fault. 1203 * 1204 * The goto's are kind of ugly, but this streamlines the normal case of having 1205 * it in the page cache, and handles the special cases reasonably without 1206 * having a lot of duplicated code. 1207 */ 1208struct page *filemap_nopage(struct vm_area_struct *area, 1209 unsigned long address, int *type) 1210{ 1211 int error; 1212 struct file *file = area->vm_file; 1213 struct address_space *mapping = file->f_mapping; 1214 struct file_ra_state *ra = &file->f_ra; 1215 struct inode *inode = mapping->host; 1216 struct page *page; 1217 unsigned long size, pgoff; 1218 int did_readaround = 0, majmin = VM_FAULT_MINOR; 1219 1220 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; 1221 1222retry_all: 1223 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 1224 if (pgoff >= size) 1225 goto outside_data_content; 1226 1227 /* If we don't want any read-ahead, don't bother */ 1228 if (VM_RandomReadHint(area)) 1229 goto no_cached_page; 1230 1231 /* 1232 * The readahead code wants to be told about each and every page 1233 * so it can build and shrink its windows appropriately 1234 * 1235 * For sequential accesses, we use the generic readahead logic. 1236 */ 1237 if (VM_SequentialReadHint(area)) 1238 page_cache_readahead(mapping, ra, file, pgoff, 1); 1239 1240 /* 1241 * Do we have something in the page cache already? 1242 */ 1243retry_find: 1244 page = find_get_page(mapping, pgoff); 1245 if (!page) { 1246 unsigned long ra_pages; 1247 1248 if (VM_SequentialReadHint(area)) { 1249 handle_ra_miss(mapping, ra, pgoff); 1250 goto no_cached_page; 1251 } 1252 ra->mmap_miss++; 1253 1254 /* 1255 * Do we miss much more than hit in this file? If so, 1256 * stop bothering with read-ahead. It will only hurt. 1257 */ 1258 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS) 1259 goto no_cached_page; 1260 1261 /* 1262 * To keep the pgmajfault counter straight, we need to 1263 * check did_readaround, as this is an inner loop. 1264 */ 1265 if (!did_readaround) { 1266 majmin = VM_FAULT_MAJOR; 1267 inc_page_state(pgmajfault); 1268 } 1269 did_readaround = 1; 1270 ra_pages = max_sane_readahead(file->f_ra.ra_pages); 1271 if (ra_pages) { 1272 pgoff_t start = 0; 1273 1274 if (pgoff > ra_pages / 2) 1275 start = pgoff - ra_pages / 2; 1276 do_page_cache_readahead(mapping, file, start, ra_pages); 1277 } 1278 page = find_get_page(mapping, pgoff); 1279 if (!page) 1280 goto no_cached_page; 1281 } 1282 1283 if (!did_readaround) 1284 ra->mmap_hit++; 1285 1286 /* 1287 * Ok, found a page in the page cache, now we need to check 1288 * that it's up-to-date. 1289 */ 1290 if (!PageUptodate(page)) 1291 goto page_not_uptodate; 1292 1293success: 1294 /* 1295 * Found the page and have a reference on it. 1296 */ 1297 mark_page_accessed(page); 1298 if (type) 1299 *type = majmin; 1300 return page; 1301 1302outside_data_content: 1303 /* 1304 * An external ptracer can access pages that normally aren't 1305 * accessible.. 1306 */ 1307 if (area->vm_mm == current->mm) 1308 return NULL; 1309 /* Fall through to the non-read-ahead case */ 1310no_cached_page: 1311 /* 1312 * We're only likely to ever get here if MADV_RANDOM is in 1313 * effect. 1314 */ 1315 error = page_cache_read(file, pgoff); 1316 grab_swap_token(); 1317 1318 /* 1319 * The page we want has now been added to the page cache. 1320 * In the unlikely event that someone removed it in the 1321 * meantime, we'll just come back here and read it again. 1322 */ 1323 if (error >= 0) 1324 goto retry_find; 1325 1326 /* 1327 * An error return from page_cache_read can result if the 1328 * system is low on memory, or a problem occurs while trying 1329 * to schedule I/O. 1330 */ 1331 if (error == -ENOMEM) 1332 return NOPAGE_OOM; 1333 return NULL; 1334 1335page_not_uptodate: 1336 if (!did_readaround) { 1337 majmin = VM_FAULT_MAJOR; 1338 inc_page_state(pgmajfault); 1339 } 1340 lock_page(page); 1341 1342 /* Did it get unhashed while we waited for it? */ 1343 if (!page->mapping) { 1344 unlock_page(page); 1345 page_cache_release(page); 1346 goto retry_all; 1347 } 1348 1349 /* Did somebody else get it up-to-date? */ 1350 if (PageUptodate(page)) { 1351 unlock_page(page); 1352 goto success; 1353 } 1354 1355 error = mapping->a_ops->readpage(file, page); 1356 if (!error) { 1357 wait_on_page_locked(page); 1358 if (PageUptodate(page)) 1359 goto success; 1360 } else if (error == AOP_TRUNCATED_PAGE) { 1361 page_cache_release(page); 1362 goto retry_find; 1363 } 1364 1365 /* 1366 * Umm, take care of errors if the page isn't up-to-date. 1367 * Try to re-read it _once_. We do this synchronously, 1368 * because there really aren't any performance issues here 1369 * and we need to check for errors. 1370 */ 1371 lock_page(page); 1372 1373 /* Somebody truncated the page on us? */ 1374 if (!page->mapping) { 1375 unlock_page(page); 1376 page_cache_release(page); 1377 goto retry_all; 1378 } 1379 1380 /* Somebody else successfully read it in? */ 1381 if (PageUptodate(page)) { 1382 unlock_page(page); 1383 goto success; 1384 } 1385 ClearPageError(page); 1386 error = mapping->a_ops->readpage(file, page); 1387 if (!error) { 1388 wait_on_page_locked(page); 1389 if (PageUptodate(page)) 1390 goto success; 1391 } else if (error == AOP_TRUNCATED_PAGE) { 1392 page_cache_release(page); 1393 goto retry_find; 1394 } 1395 1396 /* 1397 * Things didn't work out. Return zero to tell the 1398 * mm layer so, possibly freeing the page cache page first. 1399 */ 1400 page_cache_release(page); 1401 return NULL; 1402} 1403 1404EXPORT_SYMBOL(filemap_nopage); 1405 1406static struct page * filemap_getpage(struct file *file, unsigned long pgoff, 1407 int nonblock) 1408{ 1409 struct address_space *mapping = file->f_mapping; 1410 struct page *page; 1411 int error; 1412 1413 /* 1414 * Do we have something in the page cache already? 1415 */ 1416retry_find: 1417 page = find_get_page(mapping, pgoff); 1418 if (!page) { 1419 if (nonblock) 1420 return NULL; 1421 goto no_cached_page; 1422 } 1423 1424 /* 1425 * Ok, found a page in the page cache, now we need to check 1426 * that it's up-to-date. 1427 */ 1428 if (!PageUptodate(page)) { 1429 if (nonblock) { 1430 page_cache_release(page); 1431 return NULL; 1432 } 1433 goto page_not_uptodate; 1434 } 1435 1436success: 1437 /* 1438 * Found the page and have a reference on it. 1439 */ 1440 mark_page_accessed(page); 1441 return page; 1442 1443no_cached_page: 1444 error = page_cache_read(file, pgoff); 1445 1446 /* 1447 * The page we want has now been added to the page cache. 1448 * In the unlikely event that someone removed it in the 1449 * meantime, we'll just come back here and read it again. 1450 */ 1451 if (error >= 0) 1452 goto retry_find; 1453 1454 /* 1455 * An error return from page_cache_read can result if the 1456 * system is low on memory, or a problem occurs while trying 1457 * to schedule I/O. 1458 */ 1459 return NULL; 1460 1461page_not_uptodate: 1462 lock_page(page); 1463 1464 /* Did it get unhashed while we waited for it? */ 1465 if (!page->mapping) { 1466 unlock_page(page); 1467 goto err; 1468 } 1469 1470 /* Did somebody else get it up-to-date? */ 1471 if (PageUptodate(page)) { 1472 unlock_page(page); 1473 goto success; 1474 } 1475 1476 error = mapping->a_ops->readpage(file, page); 1477 if (!error) { 1478 wait_on_page_locked(page); 1479 if (PageUptodate(page)) 1480 goto success; 1481 } else if (error == AOP_TRUNCATED_PAGE) { 1482 page_cache_release(page); 1483 goto retry_find; 1484 } 1485 1486 /* 1487 * Umm, take care of errors if the page isn't up-to-date. 1488 * Try to re-read it _once_. We do this synchronously, 1489 * because there really aren't any performance issues here 1490 * and we need to check for errors. 1491 */ 1492 lock_page(page); 1493 1494 /* Somebody truncated the page on us? */ 1495 if (!page->mapping) { 1496 unlock_page(page); 1497 goto err; 1498 } 1499 /* Somebody else successfully read it in? */ 1500 if (PageUptodate(page)) { 1501 unlock_page(page); 1502 goto success; 1503 } 1504 1505 ClearPageError(page); 1506 error = mapping->a_ops->readpage(file, page); 1507 if (!error) { 1508 wait_on_page_locked(page); 1509 if (PageUptodate(page)) 1510 goto success; 1511 } else if (error == AOP_TRUNCATED_PAGE) { 1512 page_cache_release(page); 1513 goto retry_find; 1514 } 1515 1516 /* 1517 * Things didn't work out. Return zero to tell the 1518 * mm layer so, possibly freeing the page cache page first. 1519 */ 1520err: 1521 page_cache_release(page); 1522 1523 return NULL; 1524} 1525 1526int filemap_populate(struct vm_area_struct *vma, unsigned long addr, 1527 unsigned long len, pgprot_t prot, unsigned long pgoff, 1528 int nonblock) 1529{ 1530 struct file *file = vma->vm_file; 1531 struct address_space *mapping = file->f_mapping; 1532 struct inode *inode = mapping->host; 1533 unsigned long size; 1534 struct mm_struct *mm = vma->vm_mm; 1535 struct page *page; 1536 int err; 1537 1538 if (!nonblock) 1539 force_page_cache_readahead(mapping, vma->vm_file, 1540 pgoff, len >> PAGE_CACHE_SHIFT); 1541 1542repeat: 1543 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 1544 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) 1545 return -EINVAL; 1546 1547 page = filemap_getpage(file, pgoff, nonblock); 1548 1549 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as 1550 * done in shmem_populate calling shmem_getpage */ 1551 if (!page && !nonblock) 1552 return -ENOMEM; 1553 1554 if (page) { 1555 err = install_page(mm, vma, addr, page, prot); 1556 if (err) { 1557 page_cache_release(page); 1558 return err; 1559 } 1560 } else if (vma->vm_flags & VM_NONLINEAR) { 1561 /* No page was found just because we can't read it in now (being 1562 * here implies nonblock != 0), but the page may exist, so set 1563 * the PTE to fault it in later. */ 1564 err = install_file_pte(mm, vma, addr, pgoff, prot); 1565 if (err) 1566 return err; 1567 } 1568 1569 len -= PAGE_SIZE; 1570 addr += PAGE_SIZE; 1571 pgoff++; 1572 if (len) 1573 goto repeat; 1574 1575 return 0; 1576} 1577EXPORT_SYMBOL(filemap_populate); 1578 1579struct vm_operations_struct generic_file_vm_ops = { 1580 .nopage = filemap_nopage, 1581 .populate = filemap_populate, 1582}; 1583 1584/* This is used for a general mmap of a disk file */ 1585 1586int generic_file_mmap(struct file * file, struct vm_area_struct * vma) 1587{ 1588 struct address_space *mapping = file->f_mapping; 1589 1590 if (!mapping->a_ops->readpage) 1591 return -ENOEXEC; 1592 file_accessed(file); 1593 vma->vm_ops = &generic_file_vm_ops; 1594 return 0; 1595} 1596 1597/* 1598 * This is for filesystems which do not implement ->writepage. 1599 */ 1600int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) 1601{ 1602 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) 1603 return -EINVAL; 1604 return generic_file_mmap(file, vma); 1605} 1606#else 1607int generic_file_mmap(struct file * file, struct vm_area_struct * vma) 1608{ 1609 return -ENOSYS; 1610} 1611int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) 1612{ 1613 return -ENOSYS; 1614} 1615#endif /* CONFIG_MMU */ 1616 1617EXPORT_SYMBOL(generic_file_mmap); 1618EXPORT_SYMBOL(generic_file_readonly_mmap); 1619 1620static inline struct page *__read_cache_page(struct address_space *mapping, 1621 unsigned long index, 1622 int (*filler)(void *,struct page*), 1623 void *data) 1624{ 1625 struct page *page, *cached_page = NULL; 1626 int err; 1627repeat: 1628 page = find_get_page(mapping, index); 1629 if (!page) { 1630 if (!cached_page) { 1631 cached_page = page_cache_alloc_cold(mapping); 1632 if (!cached_page) 1633 return ERR_PTR(-ENOMEM); 1634 } 1635 err = add_to_page_cache_lru(cached_page, mapping, 1636 index, GFP_KERNEL); 1637 if (err == -EEXIST) 1638 goto repeat; 1639 if (err < 0) { 1640 /* Presumably ENOMEM for radix tree node */ 1641 page_cache_release(cached_page); 1642 return ERR_PTR(err); 1643 } 1644 page = cached_page; 1645 cached_page = NULL; 1646 err = filler(data, page); 1647 if (err < 0) { 1648 page_cache_release(page); 1649 page = ERR_PTR(err); 1650 } 1651 } 1652 if (cached_page) 1653 page_cache_release(cached_page); 1654 return page; 1655} 1656 1657/* 1658 * Read into the page cache. If a page already exists, 1659 * and PageUptodate() is not set, try to fill the page. 1660 */ 1661struct page *read_cache_page(struct address_space *mapping, 1662 unsigned long index, 1663 int (*filler)(void *,struct page*), 1664 void *data) 1665{ 1666 struct page *page; 1667 int err; 1668 1669retry: 1670 page = __read_cache_page(mapping, index, filler, data); 1671 if (IS_ERR(page)) 1672 goto out; 1673 mark_page_accessed(page); 1674 if (PageUptodate(page)) 1675 goto out; 1676 1677 lock_page(page); 1678 if (!page->mapping) { 1679 unlock_page(page); 1680 page_cache_release(page); 1681 goto retry; 1682 } 1683 if (PageUptodate(page)) { 1684 unlock_page(page); 1685 goto out; 1686 } 1687 err = filler(data, page); 1688 if (err < 0) { 1689 page_cache_release(page); 1690 page = ERR_PTR(err); 1691 } 1692 out: 1693 return page; 1694} 1695 1696EXPORT_SYMBOL(read_cache_page); 1697 1698/* 1699 * If the page was newly created, increment its refcount and add it to the 1700 * caller's lru-buffering pagevec. This function is specifically for 1701 * generic_file_write(). 1702 */ 1703static inline struct page * 1704__grab_cache_page(struct address_space *mapping, unsigned long index, 1705 struct page **cached_page, struct pagevec *lru_pvec) 1706{ 1707 int err; 1708 struct page *page; 1709repeat: 1710 page = find_lock_page(mapping, index); 1711 if (!page) { 1712 if (!*cached_page) { 1713 *cached_page = page_cache_alloc(mapping); 1714 if (!*cached_page) 1715 return NULL; 1716 } 1717 err = add_to_page_cache(*cached_page, mapping, 1718 index, GFP_KERNEL); 1719 if (err == -EEXIST) 1720 goto repeat; 1721 if (err == 0) { 1722 page = *cached_page; 1723 page_cache_get(page); 1724 if (!pagevec_add(lru_pvec, page)) 1725 __pagevec_lru_add(lru_pvec); 1726 *cached_page = NULL; 1727 } 1728 } 1729 return page; 1730} 1731 1732/* 1733 * The logic we want is 1734 * 1735 * if suid or (sgid and xgrp) 1736 * remove privs 1737 */ 1738int remove_suid(struct dentry *dentry) 1739{ 1740 mode_t mode = dentry->d_inode->i_mode; 1741 int kill = 0; 1742 int result = 0; 1743 1744 /* suid always must be killed */ 1745 if (unlikely(mode & S_ISUID)) 1746 kill = ATTR_KILL_SUID; 1747 1748 /* 1749 * sgid without any exec bits is just a mandatory locking mark; leave 1750 * it alone. If some exec bits are set, it's a real sgid; kill it. 1751 */ 1752 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) 1753 kill |= ATTR_KILL_SGID; 1754 1755 if (unlikely(kill && !capable(CAP_FSETID))) { 1756 struct iattr newattrs; 1757 1758 newattrs.ia_valid = ATTR_FORCE | kill; 1759 result = notify_change(dentry, &newattrs); 1760 } 1761 return result; 1762} 1763EXPORT_SYMBOL(remove_suid); 1764 1765size_t 1766__filemap_copy_from_user_iovec(char *vaddr, 1767 const struct iovec *iov, size_t base, size_t bytes) 1768{ 1769 size_t copied = 0, left = 0; 1770 1771 while (bytes) { 1772 char __user *buf = iov->iov_base + base; 1773 int copy = min(bytes, iov->iov_len - base); 1774 1775 base = 0; 1776 left = __copy_from_user_inatomic(vaddr, buf, copy); 1777 copied += copy; 1778 bytes -= copy; 1779 vaddr += copy; 1780 iov++; 1781 1782 if (unlikely(left)) { 1783 /* zero the rest of the target like __copy_from_user */ 1784 if (bytes) 1785 memset(vaddr, 0, bytes); 1786 break; 1787 } 1788 } 1789 return copied - left; 1790} 1791 1792/* 1793 * Performs necessary checks before doing a write 1794 * 1795 * Can adjust writing position aor amount of bytes to write. 1796 * Returns appropriate error code that caller should return or 1797 * zero in case that write should be allowed. 1798 */ 1799inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) 1800{ 1801 struct inode *inode = file->f_mapping->host; 1802 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1803 1804 if (unlikely(*pos < 0)) 1805 return -EINVAL; 1806 1807 if (!isblk) { 1808 /* FIXME: this is for backwards compatibility with 2.4 */ 1809 if (file->f_flags & O_APPEND) 1810 *pos = i_size_read(inode); 1811 1812 if (limit != RLIM_INFINITY) { 1813 if (*pos >= limit) { 1814 send_sig(SIGXFSZ, current, 0); 1815 return -EFBIG; 1816 } 1817 if (*count > limit - (typeof(limit))*pos) { 1818 *count = limit - (typeof(limit))*pos; 1819 } 1820 } 1821 } 1822 1823 /* 1824 * LFS rule 1825 */ 1826 if (unlikely(*pos + *count > MAX_NON_LFS && 1827 !(file->f_flags & O_LARGEFILE))) { 1828 if (*pos >= MAX_NON_LFS) { 1829 send_sig(SIGXFSZ, current, 0); 1830 return -EFBIG; 1831 } 1832 if (*count > MAX_NON_LFS - (unsigned long)*pos) { 1833 *count = MAX_NON_LFS - (unsigned long)*pos; 1834 } 1835 } 1836 1837 /* 1838 * Are we about to exceed the fs block limit ? 1839 * 1840 * If we have written data it becomes a short write. If we have 1841 * exceeded without writing data we send a signal and return EFBIG. 1842 * Linus frestrict idea will clean these up nicely.. 1843 */ 1844 if (likely(!isblk)) { 1845 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { 1846 if (*count || *pos > inode->i_sb->s_maxbytes) { 1847 send_sig(SIGXFSZ, current, 0); 1848 return -EFBIG; 1849 } 1850 /* zero-length writes at ->s_maxbytes are OK */ 1851 } 1852 1853 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) 1854 *count = inode->i_sb->s_maxbytes - *pos; 1855 } else { 1856 loff_t isize; 1857 if (bdev_read_only(I_BDEV(inode))) 1858 return -EPERM; 1859 isize = i_size_read(inode); 1860 if (*pos >= isize) { 1861 if (*count || *pos > isize) 1862 return -ENOSPC; 1863 } 1864 1865 if (*pos + *count > isize) 1866 *count = isize - *pos; 1867 } 1868 return 0; 1869} 1870EXPORT_SYMBOL(generic_write_checks); 1871 1872ssize_t 1873generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, 1874 unsigned long *nr_segs, loff_t pos, loff_t *ppos, 1875 size_t count, size_t ocount) 1876{ 1877 struct file *file = iocb->ki_filp; 1878 struct address_space *mapping = file->f_mapping; 1879 struct inode *inode = mapping->host; 1880 ssize_t written; 1881 1882 if (count != ocount) 1883 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); 1884 1885 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); 1886 if (written > 0) { 1887 loff_t end = pos + written; 1888 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { 1889 i_size_write(inode, end); 1890 mark_inode_dirty(inode); 1891 } 1892 *ppos = end; 1893 } 1894 1895 /* 1896 * Sync the fs metadata but not the minor inode changes and 1897 * of course not the data as we did direct DMA for the IO. 1898 * i_mutex is held, which protects generic_osync_inode() from 1899 * livelocking. 1900 */ 1901 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 1902 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); 1903 if (err < 0) 1904 written = err; 1905 } 1906 if (written == count && !is_sync_kiocb(iocb)) 1907 written = -EIOCBQUEUED; 1908 return written; 1909} 1910EXPORT_SYMBOL(generic_file_direct_write); 1911 1912ssize_t 1913generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, 1914 unsigned long nr_segs, loff_t pos, loff_t *ppos, 1915 size_t count, ssize_t written) 1916{ 1917 struct file *file = iocb->ki_filp; 1918 struct address_space * mapping = file->f_mapping; 1919 struct address_space_operations *a_ops = mapping->a_ops; 1920 struct inode *inode = mapping->host; 1921 long status = 0; 1922 struct page *page; 1923 struct page *cached_page = NULL; 1924 size_t bytes; 1925 struct pagevec lru_pvec; 1926 const struct iovec *cur_iov = iov; /* current iovec */ 1927 size_t iov_base = 0; /* offset in the current iovec */ 1928 char __user *buf; 1929 1930 pagevec_init(&lru_pvec, 0); 1931 1932 /* 1933 * handle partial DIO write. Adjust cur_iov if needed. 1934 */ 1935 if (likely(nr_segs == 1)) 1936 buf = iov->iov_base + written; 1937 else { 1938 filemap_set_next_iovec(&cur_iov, &iov_base, written); 1939 buf = cur_iov->iov_base + iov_base; 1940 } 1941 1942 do { 1943 unsigned long index; 1944 unsigned long offset; 1945 unsigned long maxlen; 1946 size_t copied; 1947 1948 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1949 index = pos >> PAGE_CACHE_SHIFT; 1950 bytes = PAGE_CACHE_SIZE - offset; 1951 if (bytes > count) 1952 bytes = count; 1953 1954 /* 1955 * Bring in the user page that we will copy from _first_. 1956 * Otherwise there's a nasty deadlock on copying from the 1957 * same page as we're writing to, without it being marked 1958 * up-to-date. 1959 */ 1960 maxlen = cur_iov->iov_len - iov_base; 1961 if (maxlen > bytes) 1962 maxlen = bytes; 1963 fault_in_pages_readable(buf, maxlen); 1964 1965 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); 1966 if (!page) { 1967 status = -ENOMEM; 1968 break; 1969 } 1970 1971 status = a_ops->prepare_write(file, page, offset, offset+bytes); 1972 if (unlikely(status)) { 1973 loff_t isize = i_size_read(inode); 1974 1975 if (status != AOP_TRUNCATED_PAGE) 1976 unlock_page(page); 1977 page_cache_release(page); 1978 if (status == AOP_TRUNCATED_PAGE) 1979 continue; 1980 /* 1981 * prepare_write() may have instantiated a few blocks 1982 * outside i_size. Trim these off again. 1983 */ 1984 if (pos + bytes > isize) 1985 vmtruncate(inode, isize); 1986 break; 1987 } 1988 if (likely(nr_segs == 1)) 1989 copied = filemap_copy_from_user(page, offset, 1990 buf, bytes); 1991 else 1992 copied = filemap_copy_from_user_iovec(page, offset, 1993 cur_iov, iov_base, bytes); 1994 flush_dcache_page(page); 1995 status = a_ops->commit_write(file, page, offset, offset+bytes); 1996 if (status == AOP_TRUNCATED_PAGE) { 1997 page_cache_release(page); 1998 continue; 1999 } 2000 if (likely(copied > 0)) { 2001 if (!status) 2002 status = copied; 2003 2004 if (status >= 0) { 2005 written += status; 2006 count -= status; 2007 pos += status; 2008 buf += status; 2009 if (unlikely(nr_segs > 1)) { 2010 filemap_set_next_iovec(&cur_iov, 2011 &iov_base, status); 2012 if (count) 2013 buf = cur_iov->iov_base + 2014 iov_base; 2015 } else { 2016 iov_base += status; 2017 } 2018 } 2019 } 2020 if (unlikely(copied != bytes)) 2021 if (status >= 0) 2022 status = -EFAULT; 2023 unlock_page(page); 2024 mark_page_accessed(page); 2025 page_cache_release(page); 2026 if (status < 0) 2027 break; 2028 balance_dirty_pages_ratelimited(mapping); 2029 cond_resched(); 2030 } while (count); 2031 *ppos = pos; 2032 2033 if (cached_page) 2034 page_cache_release(cached_page); 2035 2036 /* 2037 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC 2038 */ 2039 if (likely(status >= 0)) { 2040 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2041 if (!a_ops->writepage || !is_sync_kiocb(iocb)) 2042 status = generic_osync_inode(inode, mapping, 2043 OSYNC_METADATA|OSYNC_DATA); 2044 } 2045 } 2046 2047 /* 2048 * If we get here for O_DIRECT writes then we must have fallen through 2049 * to buffered writes (block instantiation inside i_size). So we sync 2050 * the file data here, to try to honour O_DIRECT expectations. 2051 */ 2052 if (unlikely(file->f_flags & O_DIRECT) && written) 2053 status = filemap_write_and_wait(mapping); 2054 2055 pagevec_lru_add(&lru_pvec); 2056 return written ? written : status; 2057} 2058EXPORT_SYMBOL(generic_file_buffered_write); 2059 2060static ssize_t 2061__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, 2062 unsigned long nr_segs, loff_t *ppos) 2063{ 2064 struct file *file = iocb->ki_filp; 2065 struct address_space * mapping = file->f_mapping; 2066 size_t ocount; /* original count */ 2067 size_t count; /* after file limit checks */ 2068 struct inode *inode = mapping->host; 2069 unsigned long seg; 2070 loff_t pos; 2071 ssize_t written; 2072 ssize_t err; 2073 2074 ocount = 0; 2075 for (seg = 0; seg < nr_segs; seg++) { 2076 const struct iovec *iv = &iov[seg]; 2077 2078 /* 2079 * If any segment has a negative length, or the cumulative 2080 * length ever wraps negative then return -EINVAL. 2081 */ 2082 ocount += iv->iov_len; 2083 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) 2084 return -EINVAL; 2085 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) 2086 continue; 2087 if (seg == 0) 2088 return -EFAULT; 2089 nr_segs = seg; 2090 ocount -= iv->iov_len; /* This segment is no good */ 2091 break; 2092 } 2093 2094 count = ocount; 2095 pos = *ppos; 2096 2097 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); 2098 2099 /* We can write back this queue in page reclaim */ 2100 current->backing_dev_info = mapping->backing_dev_info; 2101 written = 0; 2102 2103 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); 2104 if (err) 2105 goto out; 2106 2107 if (count == 0) 2108 goto out; 2109 2110 err = remove_suid(file->f_dentry); 2111 if (err) 2112 goto out; 2113 2114 file_update_time(file); 2115 2116 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ 2117 if (unlikely(file->f_flags & O_DIRECT)) { 2118 written = generic_file_direct_write(iocb, iov, 2119 &nr_segs, pos, ppos, count, ocount); 2120 if (written < 0 || written == count) 2121 goto out; 2122 /* 2123 * direct-io write to a hole: fall through to buffered I/O 2124 * for completing the rest of the request. 2125 */ 2126 pos += written; 2127 count -= written; 2128 } 2129 2130 written = generic_file_buffered_write(iocb, iov, nr_segs, 2131 pos, ppos, count, written); 2132out: 2133 current->backing_dev_info = NULL; 2134 return written ? written : err; 2135} 2136EXPORT_SYMBOL(generic_file_aio_write_nolock); 2137 2138ssize_t 2139generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, 2140 unsigned long nr_segs, loff_t *ppos) 2141{ 2142 struct file *file = iocb->ki_filp; 2143 struct address_space *mapping = file->f_mapping; 2144 struct inode *inode = mapping->host; 2145 ssize_t ret; 2146 loff_t pos = *ppos; 2147 2148 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos); 2149 2150 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2151 int err; 2152 2153 err = sync_page_range_nolock(inode, mapping, pos, ret); 2154 if (err < 0) 2155 ret = err; 2156 } 2157 return ret; 2158} 2159 2160static ssize_t 2161__generic_file_write_nolock(struct file *file, const struct iovec *iov, 2162 unsigned long nr_segs, loff_t *ppos) 2163{ 2164 struct kiocb kiocb; 2165 ssize_t ret; 2166 2167 init_sync_kiocb(&kiocb, file); 2168 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); 2169 if (ret == -EIOCBQUEUED) 2170 ret = wait_on_sync_kiocb(&kiocb); 2171 return ret; 2172} 2173 2174ssize_t 2175generic_file_write_nolock(struct file *file, const struct iovec *iov, 2176 unsigned long nr_segs, loff_t *ppos) 2177{ 2178 struct kiocb kiocb; 2179 ssize_t ret; 2180 2181 init_sync_kiocb(&kiocb, file); 2182 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); 2183 if (-EIOCBQUEUED == ret) 2184 ret = wait_on_sync_kiocb(&kiocb); 2185 return ret; 2186} 2187EXPORT_SYMBOL(generic_file_write_nolock); 2188 2189ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf, 2190 size_t count, loff_t pos) 2191{ 2192 struct file *file = iocb->ki_filp; 2193 struct address_space *mapping = file->f_mapping; 2194 struct inode *inode = mapping->host; 2195 ssize_t ret; 2196 struct iovec local_iov = { .iov_base = (void __user *)buf, 2197 .iov_len = count }; 2198 2199 BUG_ON(iocb->ki_pos != pos); 2200 2201 mutex_lock(&inode->i_mutex); 2202 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1, 2203 &iocb->ki_pos); 2204 mutex_unlock(&inode->i_mutex); 2205 2206 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2207 ssize_t err; 2208 2209 err = sync_page_range(inode, mapping, pos, ret); 2210 if (err < 0) 2211 ret = err; 2212 } 2213 return ret; 2214} 2215EXPORT_SYMBOL(generic_file_aio_write); 2216 2217ssize_t generic_file_write(struct file *file, const char __user *buf, 2218 size_t count, loff_t *ppos) 2219{ 2220 struct address_space *mapping = file->f_mapping; 2221 struct inode *inode = mapping->host; 2222 ssize_t ret; 2223 struct iovec local_iov = { .iov_base = (void __user *)buf, 2224 .iov_len = count }; 2225 2226 mutex_lock(&inode->i_mutex); 2227 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos); 2228 mutex_unlock(&inode->i_mutex); 2229 2230 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2231 ssize_t err; 2232 2233 err = sync_page_range(inode, mapping, *ppos - ret, ret); 2234 if (err < 0) 2235 ret = err; 2236 } 2237 return ret; 2238} 2239EXPORT_SYMBOL(generic_file_write); 2240 2241ssize_t generic_file_readv(struct file *filp, const struct iovec *iov, 2242 unsigned long nr_segs, loff_t *ppos) 2243{ 2244 struct kiocb kiocb; 2245 ssize_t ret; 2246 2247 init_sync_kiocb(&kiocb, filp); 2248 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos); 2249 if (-EIOCBQUEUED == ret) 2250 ret = wait_on_sync_kiocb(&kiocb); 2251 return ret; 2252} 2253EXPORT_SYMBOL(generic_file_readv); 2254 2255ssize_t generic_file_writev(struct file *file, const struct iovec *iov, 2256 unsigned long nr_segs, loff_t *ppos) 2257{ 2258 struct address_space *mapping = file->f_mapping; 2259 struct inode *inode = mapping->host; 2260 ssize_t ret; 2261 2262 mutex_lock(&inode->i_mutex); 2263 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos); 2264 mutex_unlock(&inode->i_mutex); 2265 2266 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { 2267 int err; 2268 2269 err = sync_page_range(inode, mapping, *ppos - ret, ret); 2270 if (err < 0) 2271 ret = err; 2272 } 2273 return ret; 2274} 2275EXPORT_SYMBOL(generic_file_writev); 2276 2277/* 2278 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something 2279 * went wrong during pagecache shootdown. 2280 */ 2281static ssize_t 2282generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, 2283 loff_t offset, unsigned long nr_segs) 2284{ 2285 struct file *file = iocb->ki_filp; 2286 struct address_space *mapping = file->f_mapping; 2287 ssize_t retval; 2288 size_t write_len = 0; 2289 2290 /* 2291 * If it's a write, unmap all mmappings of the file up-front. This 2292 * will cause any pte dirty bits to be propagated into the pageframes 2293 * for the subsequent filemap_write_and_wait(). 2294 */ 2295 if (rw == WRITE) { 2296 write_len = iov_length(iov, nr_segs); 2297 if (mapping_mapped(mapping)) 2298 unmap_mapping_range(mapping, offset, write_len, 0); 2299 } 2300 2301 retval = filemap_write_and_wait(mapping); 2302 if (retval == 0) { 2303 retval = mapping->a_ops->direct_IO(rw, iocb, iov, 2304 offset, nr_segs); 2305 if (rw == WRITE && mapping->nrpages) { 2306 pgoff_t end = (offset + write_len - 1) 2307 >> PAGE_CACHE_SHIFT; 2308 int err = invalidate_inode_pages2_range(mapping, 2309 offset >> PAGE_CACHE_SHIFT, end); 2310 if (err) 2311 retval = err; 2312 } 2313 } 2314 return retval; 2315} 2316