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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 goto page_not_uptodate;
1384
1385success:
1386 /*
1387 * Found the page and have a reference on it.
1388 */
1389 mark_page_accessed(page);
1390 return page;
1391
1392no_cached_page:
1393 error = page_cache_read(file, pgoff);
1394
1395 /*
1396 * The page we want has now been added to the page cache.
1397 * In the unlikely event that someone removed it in the
1398 * meantime, we'll just come back here and read it again.
1399 */
1400 if (error >= 0)
1401 goto retry_find;
1402
1403 /*
1404 * An error return from page_cache_read can result if the
1405 * system is low on memory, or a problem occurs while trying
1406 * to schedule I/O.
1407 */
1408 return NULL;
1409
1410page_not_uptodate:
1411 lock_page(page);
1412
1413 /* Did it get unhashed while we waited for it? */
1414 if (!page->mapping) {
1415 unlock_page(page);
1416 goto err;
1417 }
1418
1419 /* Did somebody else get it up-to-date? */
1420 if (PageUptodate(page)) {
1421 unlock_page(page);
1422 goto success;
1423 }
1424
1425 if (!mapping->a_ops->readpage(file, page)) {
1426 wait_on_page_locked(page);
1427 if (PageUptodate(page))
1428 goto success;
1429 }
1430
1431 /*
1432 * Umm, take care of errors if the page isn't up-to-date.
1433 * Try to re-read it _once_. We do this synchronously,
1434 * because there really aren't any performance issues here
1435 * and we need to check for errors.
1436 */
1437 lock_page(page);
1438
1439 /* Somebody truncated the page on us? */
1440 if (!page->mapping) {
1441 unlock_page(page);
1442 goto err;
1443 }
1444 /* Somebody else successfully read it in? */
1445 if (PageUptodate(page)) {
1446 unlock_page(page);
1447 goto success;
1448 }
1449
1450 ClearPageError(page);
1451 if (!mapping->a_ops->readpage(file, page)) {
1452 wait_on_page_locked(page);
1453 if (PageUptodate(page))
1454 goto success;
1455 }
1456
1457 /*
1458 * Things didn't work out. Return zero to tell the
1459 * mm layer so, possibly freeing the page cache page first.
1460 */
1461err:
1462 page_cache_release(page);
1463
1464 return NULL;
1465}
1466
1467int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1468 unsigned long len, pgprot_t prot, unsigned long pgoff,
1469 int nonblock)
1470{
1471 struct file *file = vma->vm_file;
1472 struct address_space *mapping = file->f_mapping;
1473 struct inode *inode = mapping->host;
1474 unsigned long size;
1475 struct mm_struct *mm = vma->vm_mm;
1476 struct page *page;
1477 int err;
1478
1479 if (!nonblock)
1480 force_page_cache_readahead(mapping, vma->vm_file,
1481 pgoff, len >> PAGE_CACHE_SHIFT);
1482
1483repeat:
1484 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1485 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1486 return -EINVAL;
1487
1488 page = filemap_getpage(file, pgoff, nonblock);
1489 if (!page && !nonblock)
1490 return -ENOMEM;
1491 if (page) {
1492 err = install_page(mm, vma, addr, page, prot);
1493 if (err) {
1494 page_cache_release(page);
1495 return err;
1496 }
1497 } else {
1498 err = install_file_pte(mm, vma, addr, pgoff, prot);
1499 if (err)
1500 return err;
1501 }
1502
1503 len -= PAGE_SIZE;
1504 addr += PAGE_SIZE;
1505 pgoff++;
1506 if (len)
1507 goto repeat;
1508
1509 return 0;
1510}
1511
1512struct vm_operations_struct generic_file_vm_ops = {
1513 .nopage = filemap_nopage,
1514 .populate = filemap_populate,
1515};
1516
1517/* This is used for a general mmap of a disk file */
1518
1519int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1520{
1521 struct address_space *mapping = file->f_mapping;
1522
1523 if (!mapping->a_ops->readpage)
1524 return -ENOEXEC;
1525 file_accessed(file);
1526 vma->vm_ops = &generic_file_vm_ops;
1527 return 0;
1528}
1529EXPORT_SYMBOL(filemap_populate);
1530
1531/*
1532 * This is for filesystems which do not implement ->writepage.
1533 */
1534int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1535{
1536 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1537 return -EINVAL;
1538 return generic_file_mmap(file, vma);
1539}
1540#else
1541int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1542{
1543 return -ENOSYS;
1544}
1545int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1546{
1547 return -ENOSYS;
1548}
1549#endif /* CONFIG_MMU */
1550
1551EXPORT_SYMBOL(generic_file_mmap);
1552EXPORT_SYMBOL(generic_file_readonly_mmap);
1553
1554static inline struct page *__read_cache_page(struct address_space *mapping,
1555 unsigned long index,
1556 int (*filler)(void *,struct page*),
1557 void *data)
1558{
1559 struct page *page, *cached_page = NULL;
1560 int err;
1561repeat:
1562 page = find_get_page(mapping, index);
1563 if (!page) {
1564 if (!cached_page) {
1565 cached_page = page_cache_alloc_cold(mapping);
1566 if (!cached_page)
1567 return ERR_PTR(-ENOMEM);
1568 }
1569 err = add_to_page_cache_lru(cached_page, mapping,
1570 index, GFP_KERNEL);
1571 if (err == -EEXIST)
1572 goto repeat;
1573 if (err < 0) {
1574 /* Presumably ENOMEM for radix tree node */
1575 page_cache_release(cached_page);
1576 return ERR_PTR(err);
1577 }
1578 page = cached_page;
1579 cached_page = NULL;
1580 err = filler(data, page);
1581 if (err < 0) {
1582 page_cache_release(page);
1583 page = ERR_PTR(err);
1584 }
1585 }
1586 if (cached_page)
1587 page_cache_release(cached_page);
1588 return page;
1589}
1590
1591/*
1592 * Read into the page cache. If a page already exists,
1593 * and PageUptodate() is not set, try to fill the page.
1594 */
1595struct page *read_cache_page(struct address_space *mapping,
1596 unsigned long index,
1597 int (*filler)(void *,struct page*),
1598 void *data)
1599{
1600 struct page *page;
1601 int err;
1602
1603retry:
1604 page = __read_cache_page(mapping, index, filler, data);
1605 if (IS_ERR(page))
1606 goto out;
1607 mark_page_accessed(page);
1608 if (PageUptodate(page))
1609 goto out;
1610
1611 lock_page(page);
1612 if (!page->mapping) {
1613 unlock_page(page);
1614 page_cache_release(page);
1615 goto retry;
1616 }
1617 if (PageUptodate(page)) {
1618 unlock_page(page);
1619 goto out;
1620 }
1621 err = filler(data, page);
1622 if (err < 0) {
1623 page_cache_release(page);
1624 page = ERR_PTR(err);
1625 }
1626 out:
1627 return page;
1628}
1629
1630EXPORT_SYMBOL(read_cache_page);
1631
1632/*
1633 * If the page was newly created, increment its refcount and add it to the
1634 * caller's lru-buffering pagevec. This function is specifically for
1635 * generic_file_write().
1636 */
1637static inline struct page *
1638__grab_cache_page(struct address_space *mapping, unsigned long index,
1639 struct page **cached_page, struct pagevec *lru_pvec)
1640{
1641 int err;
1642 struct page *page;
1643repeat:
1644 page = find_lock_page(mapping, index);
1645 if (!page) {
1646 if (!*cached_page) {
1647 *cached_page = page_cache_alloc(mapping);
1648 if (!*cached_page)
1649 return NULL;
1650 }
1651 err = add_to_page_cache(*cached_page, mapping,
1652 index, GFP_KERNEL);
1653 if (err == -EEXIST)
1654 goto repeat;
1655 if (err == 0) {
1656 page = *cached_page;
1657 page_cache_get(page);
1658 if (!pagevec_add(lru_pvec, page))
1659 __pagevec_lru_add(lru_pvec);
1660 *cached_page = NULL;
1661 }
1662 }
1663 return page;
1664}
1665
1666/*
1667 * The logic we want is
1668 *
1669 * if suid or (sgid and xgrp)
1670 * remove privs
1671 */
1672int remove_suid(struct dentry *dentry)
1673{
1674 mode_t mode = dentry->d_inode->i_mode;
1675 int kill = 0;
1676 int result = 0;
1677
1678 /* suid always must be killed */
1679 if (unlikely(mode & S_ISUID))
1680 kill = ATTR_KILL_SUID;
1681
1682 /*
1683 * sgid without any exec bits is just a mandatory locking mark; leave
1684 * it alone. If some exec bits are set, it's a real sgid; kill it.
1685 */
1686 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1687 kill |= ATTR_KILL_SGID;
1688
1689 if (unlikely(kill && !capable(CAP_FSETID))) {
1690 struct iattr newattrs;
1691
1692 newattrs.ia_valid = ATTR_FORCE | kill;
1693 result = notify_change(dentry, &newattrs);
1694 }
1695 return result;
1696}
1697EXPORT_SYMBOL(remove_suid);
1698
1699/*
1700 * Copy as much as we can into the page and return the number of bytes which
1701 * were sucessfully copied. If a fault is encountered then clear the page
1702 * out to (offset+bytes) and return the number of bytes which were copied.
1703 */
1704static inline size_t
1705filemap_copy_from_user(struct page *page, unsigned long offset,
1706 const char __user *buf, unsigned bytes)
1707{
1708 char *kaddr;
1709 int left;
1710
1711 kaddr = kmap_atomic(page, KM_USER0);
1712 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
1713 kunmap_atomic(kaddr, KM_USER0);
1714
1715 if (left != 0) {
1716 /* Do it the slow way */
1717 kaddr = kmap(page);
1718 left = __copy_from_user(kaddr + offset, buf, bytes);
1719 kunmap(page);
1720 }
1721 return bytes - left;
1722}
1723
1724static size_t
1725__filemap_copy_from_user_iovec(char *vaddr,
1726 const struct iovec *iov, size_t base, size_t bytes)
1727{
1728 size_t copied = 0, left = 0;
1729
1730 while (bytes) {
1731 char __user *buf = iov->iov_base + base;
1732 int copy = min(bytes, iov->iov_len - base);
1733
1734 base = 0;
1735 left = __copy_from_user_inatomic(vaddr, buf, copy);
1736 copied += copy;
1737 bytes -= copy;
1738 vaddr += copy;
1739 iov++;
1740
1741 if (unlikely(left)) {
1742 /* zero the rest of the target like __copy_from_user */
1743 if (bytes)
1744 memset(vaddr, 0, bytes);
1745 break;
1746 }
1747 }
1748 return copied - left;
1749}
1750
1751/*
1752 * This has the same sideeffects and return value as filemap_copy_from_user().
1753 * The difference is that on a fault we need to memset the remainder of the
1754 * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
1755 * single-segment behaviour.
1756 */
1757static inline size_t
1758filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
1759 const struct iovec *iov, size_t base, size_t bytes)
1760{
1761 char *kaddr;
1762 size_t copied;
1763
1764 kaddr = kmap_atomic(page, KM_USER0);
1765 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1766 base, bytes);
1767 kunmap_atomic(kaddr, KM_USER0);
1768 if (copied != bytes) {
1769 kaddr = kmap(page);
1770 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1771 base, bytes);
1772 kunmap(page);
1773 }
1774 return copied;
1775}
1776
1777static inline void
1778filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
1779{
1780 const struct iovec *iov = *iovp;
1781 size_t base = *basep;
1782
1783 while (bytes) {
1784 int copy = min(bytes, iov->iov_len - base);
1785
1786 bytes -= copy;
1787 base += copy;
1788 if (iov->iov_len == base) {
1789 iov++;
1790 base = 0;
1791 }
1792 }
1793 *iovp = iov;
1794 *basep = base;
1795}
1796
1797/*
1798 * Performs necessary checks before doing a write
1799 *
1800 * Can adjust writing position aor amount of bytes to write.
1801 * Returns appropriate error code that caller should return or
1802 * zero in case that write should be allowed.
1803 */
1804inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1805{
1806 struct inode *inode = file->f_mapping->host;
1807 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1808
1809 if (unlikely(*pos < 0))
1810 return -EINVAL;
1811
1812 if (unlikely(file->f_error)) {
1813 int err = file->f_error;
1814 file->f_error = 0;
1815 return err;
1816 }
1817
1818 if (!isblk) {
1819 /* FIXME: this is for backwards compatibility with 2.4 */
1820 if (file->f_flags & O_APPEND)
1821 *pos = i_size_read(inode);
1822
1823 if (limit != RLIM_INFINITY) {
1824 if (*pos >= limit) {
1825 send_sig(SIGXFSZ, current, 0);
1826 return -EFBIG;
1827 }
1828 if (*count > limit - (typeof(limit))*pos) {
1829 *count = limit - (typeof(limit))*pos;
1830 }
1831 }
1832 }
1833
1834 /*
1835 * LFS rule
1836 */
1837 if (unlikely(*pos + *count > MAX_NON_LFS &&
1838 !(file->f_flags & O_LARGEFILE))) {
1839 if (*pos >= MAX_NON_LFS) {
1840 send_sig(SIGXFSZ, current, 0);
1841 return -EFBIG;
1842 }
1843 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1844 *count = MAX_NON_LFS - (unsigned long)*pos;
1845 }
1846 }
1847
1848 /*
1849 * Are we about to exceed the fs block limit ?
1850 *
1851 * If we have written data it becomes a short write. If we have
1852 * exceeded without writing data we send a signal and return EFBIG.
1853 * Linus frestrict idea will clean these up nicely..
1854 */
1855 if (likely(!isblk)) {
1856 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1857 if (*count || *pos > inode->i_sb->s_maxbytes) {
1858 send_sig(SIGXFSZ, current, 0);
1859 return -EFBIG;
1860 }
1861 /* zero-length writes at ->s_maxbytes are OK */
1862 }
1863
1864 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1865 *count = inode->i_sb->s_maxbytes - *pos;
1866 } else {
1867 loff_t isize;
1868 if (bdev_read_only(I_BDEV(inode)))
1869 return -EPERM;
1870 isize = i_size_read(inode);
1871 if (*pos >= isize) {
1872 if (*count || *pos > isize)
1873 return -ENOSPC;
1874 }
1875
1876 if (*pos + *count > isize)
1877 *count = isize - *pos;
1878 }
1879 return 0;
1880}
1881EXPORT_SYMBOL(generic_write_checks);
1882
1883ssize_t
1884generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1885 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1886 size_t count, size_t ocount)
1887{
1888 struct file *file = iocb->ki_filp;
1889 struct address_space *mapping = file->f_mapping;
1890 struct inode *inode = mapping->host;
1891 ssize_t written;
1892
1893 if (count != ocount)
1894 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1895
1896 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1897 if (written > 0) {
1898 loff_t end = pos + written;
1899 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1900 i_size_write(inode, end);
1901 mark_inode_dirty(inode);
1902 }
1903 *ppos = end;
1904 }
1905
1906 /*
1907 * Sync the fs metadata but not the minor inode changes and
1908 * of course not the data as we did direct DMA for the IO.
1909 * i_sem is held, which protects generic_osync_inode() from
1910 * livelocking.
1911 */
1912 if (written >= 0 && file->f_flags & O_SYNC)
1913 generic_osync_inode(inode, mapping, OSYNC_METADATA);
1914 if (written == count && !is_sync_kiocb(iocb))
1915 written = -EIOCBQUEUED;
1916 return written;
1917}
1918EXPORT_SYMBOL(generic_file_direct_write);
1919
1920ssize_t
1921generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1922 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1923 size_t count, ssize_t written)
1924{
1925 struct file *file = iocb->ki_filp;
1926 struct address_space * mapping = file->f_mapping;
1927 struct address_space_operations *a_ops = mapping->a_ops;
1928 struct inode *inode = mapping->host;
1929 long status = 0;
1930 struct page *page;
1931 struct page *cached_page = NULL;
1932 size_t bytes;
1933 struct pagevec lru_pvec;
1934 const struct iovec *cur_iov = iov; /* current iovec */
1935 size_t iov_base = 0; /* offset in the current iovec */
1936 char __user *buf;
1937
1938 pagevec_init(&lru_pvec, 0);
1939
1940 /*
1941 * handle partial DIO write. Adjust cur_iov if needed.
1942 */
1943 if (likely(nr_segs == 1))
1944 buf = iov->iov_base + written;
1945 else {
1946 filemap_set_next_iovec(&cur_iov, &iov_base, written);
1947 buf = iov->iov_base + iov_base;
1948 }
1949
1950 do {
1951 unsigned long index;
1952 unsigned long offset;
1953 size_t copied;
1954
1955 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1956 index = pos >> PAGE_CACHE_SHIFT;
1957 bytes = PAGE_CACHE_SIZE - offset;
1958 if (bytes > count)
1959 bytes = count;
1960
1961 /*
1962 * Bring in the user page that we will copy from _first_.
1963 * Otherwise there's a nasty deadlock on copying from the
1964 * same page as we're writing to, without it being marked
1965 * up-to-date.
1966 */
1967 fault_in_pages_readable(buf, bytes);
1968
1969 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1970 if (!page) {
1971 status = -ENOMEM;
1972 break;
1973 }
1974
1975 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1976 if (unlikely(status)) {
1977 loff_t isize = i_size_read(inode);
1978 /*
1979 * prepare_write() may have instantiated a few blocks
1980 * outside i_size. Trim these off again.
1981 */
1982 unlock_page(page);
1983 page_cache_release(page);
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 (likely(copied > 0)) {
1997 if (!status)
1998 status = copied;
1999
2000 if (status >= 0) {
2001 written += status;
2002 count -= status;
2003 pos += status;
2004 buf += status;
2005 if (unlikely(nr_segs > 1))
2006 filemap_set_next_iovec(&cur_iov,
2007 &iov_base, status);
2008 }
2009 }
2010 if (unlikely(copied != bytes))
2011 if (status >= 0)
2012 status = -EFAULT;
2013 unlock_page(page);
2014 mark_page_accessed(page);
2015 page_cache_release(page);
2016 if (status < 0)
2017 break;
2018 balance_dirty_pages_ratelimited(mapping);
2019 cond_resched();
2020 } while (count);
2021 *ppos = pos;
2022
2023 if (cached_page)
2024 page_cache_release(cached_page);
2025
2026 /*
2027 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2028 */
2029 if (likely(status >= 0)) {
2030 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2031 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2032 status = generic_osync_inode(inode, mapping,
2033 OSYNC_METADATA|OSYNC_DATA);
2034 }
2035 }
2036
2037 /*
2038 * If we get here for O_DIRECT writes then we must have fallen through
2039 * to buffered writes (block instantiation inside i_size). So we sync
2040 * the file data here, to try to honour O_DIRECT expectations.
2041 */
2042 if (unlikely(file->f_flags & O_DIRECT) && written)
2043 status = filemap_write_and_wait(mapping);
2044
2045 pagevec_lru_add(&lru_pvec);
2046 return written ? written : status;
2047}
2048EXPORT_SYMBOL(generic_file_buffered_write);
2049
2050ssize_t
2051__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2052 unsigned long nr_segs, loff_t *ppos)
2053{
2054 struct file *file = iocb->ki_filp;
2055 struct address_space * mapping = file->f_mapping;
2056 size_t ocount; /* original count */
2057 size_t count; /* after file limit checks */
2058 struct inode *inode = mapping->host;
2059 unsigned long seg;
2060 loff_t pos;
2061 ssize_t written;
2062 ssize_t err;
2063
2064 ocount = 0;
2065 for (seg = 0; seg < nr_segs; seg++) {
2066 const struct iovec *iv = &iov[seg];
2067
2068 /*
2069 * If any segment has a negative length, or the cumulative
2070 * length ever wraps negative then return -EINVAL.
2071 */
2072 ocount += iv->iov_len;
2073 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2074 return -EINVAL;
2075 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2076 continue;
2077 if (seg == 0)
2078 return -EFAULT;
2079 nr_segs = seg;
2080 ocount -= iv->iov_len; /* This segment is no good */
2081 break;
2082 }
2083
2084 count = ocount;
2085 pos = *ppos;
2086
2087 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2088
2089 /* We can write back this queue in page reclaim */
2090 current->backing_dev_info = mapping->backing_dev_info;
2091 written = 0;
2092
2093 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2094 if (err)
2095 goto out;
2096
2097 if (count == 0)
2098 goto out;
2099
2100 err = remove_suid(file->f_dentry);
2101 if (err)
2102 goto out;
2103
2104 inode_update_time(inode, 1);
2105
2106 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2107 if (unlikely(file->f_flags & O_DIRECT)) {
2108 written = generic_file_direct_write(iocb, iov,
2109 &nr_segs, pos, ppos, count, ocount);
2110 if (written < 0 || written == count)
2111 goto out;
2112 /*
2113 * direct-io write to a hole: fall through to buffered I/O
2114 * for completing the rest of the request.
2115 */
2116 pos += written;
2117 count -= written;
2118 }
2119
2120 written = generic_file_buffered_write(iocb, iov, nr_segs,
2121 pos, ppos, count, written);
2122out:
2123 current->backing_dev_info = NULL;
2124 return written ? written : err;
2125}
2126EXPORT_SYMBOL(generic_file_aio_write_nolock);
2127
2128ssize_t
2129generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2130 unsigned long nr_segs, loff_t *ppos)
2131{
2132 struct file *file = iocb->ki_filp;
2133 struct address_space *mapping = file->f_mapping;
2134 struct inode *inode = mapping->host;
2135 ssize_t ret;
2136 loff_t pos = *ppos;
2137
2138 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2139
2140 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2141 int err;
2142
2143 err = sync_page_range_nolock(inode, mapping, pos, ret);
2144 if (err < 0)
2145 ret = err;
2146 }
2147 return ret;
2148}
2149
2150ssize_t
2151__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2152 unsigned long nr_segs, loff_t *ppos)
2153{
2154 struct kiocb kiocb;
2155 ssize_t ret;
2156
2157 init_sync_kiocb(&kiocb, file);
2158 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2159 if (ret == -EIOCBQUEUED)
2160 ret = wait_on_sync_kiocb(&kiocb);
2161 return ret;
2162}
2163
2164ssize_t
2165generic_file_write_nolock(struct file *file, const struct iovec *iov,
2166 unsigned long nr_segs, loff_t *ppos)
2167{
2168 struct kiocb kiocb;
2169 ssize_t ret;
2170
2171 init_sync_kiocb(&kiocb, file);
2172 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2173 if (-EIOCBQUEUED == ret)
2174 ret = wait_on_sync_kiocb(&kiocb);
2175 return ret;
2176}
2177EXPORT_SYMBOL(generic_file_write_nolock);
2178
2179ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2180 size_t count, loff_t pos)
2181{
2182 struct file *file = iocb->ki_filp;
2183 struct address_space *mapping = file->f_mapping;
2184 struct inode *inode = mapping->host;
2185 ssize_t ret;
2186 struct iovec local_iov = { .iov_base = (void __user *)buf,
2187 .iov_len = count };
2188
2189 BUG_ON(iocb->ki_pos != pos);
2190
2191 down(&inode->i_sem);
2192 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2193 &iocb->ki_pos);
2194 up(&inode->i_sem);
2195
2196 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2197 ssize_t err;
2198
2199 err = sync_page_range(inode, mapping, pos, ret);
2200 if (err < 0)
2201 ret = err;
2202 }
2203 return ret;
2204}
2205EXPORT_SYMBOL(generic_file_aio_write);
2206
2207ssize_t generic_file_write(struct file *file, const char __user *buf,
2208 size_t count, loff_t *ppos)
2209{
2210 struct address_space *mapping = file->f_mapping;
2211 struct inode *inode = mapping->host;
2212 ssize_t ret;
2213 struct iovec local_iov = { .iov_base = (void __user *)buf,
2214 .iov_len = count };
2215
2216 down(&inode->i_sem);
2217 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2218 up(&inode->i_sem);
2219
2220 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2221 ssize_t err;
2222
2223 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2224 if (err < 0)
2225 ret = err;
2226 }
2227 return ret;
2228}
2229EXPORT_SYMBOL(generic_file_write);
2230
2231ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2232 unsigned long nr_segs, loff_t *ppos)
2233{
2234 struct kiocb kiocb;
2235 ssize_t ret;
2236
2237 init_sync_kiocb(&kiocb, filp);
2238 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2239 if (-EIOCBQUEUED == ret)
2240 ret = wait_on_sync_kiocb(&kiocb);
2241 return ret;
2242}
2243EXPORT_SYMBOL(generic_file_readv);
2244
2245ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2246 unsigned long nr_segs, loff_t *ppos)
2247{
2248 struct address_space *mapping = file->f_mapping;
2249 struct inode *inode = mapping->host;
2250 ssize_t ret;
2251
2252 down(&inode->i_sem);
2253 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2254 up(&inode->i_sem);
2255
2256 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2257 int err;
2258
2259 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2260 if (err < 0)
2261 ret = err;
2262 }
2263 return ret;
2264}
2265EXPORT_SYMBOL(generic_file_writev);
2266
2267/*
2268 * Called under i_sem for writes to S_ISREG files. Returns -EIO if something
2269 * went wrong during pagecache shootdown.
2270 */
2271ssize_t
2272generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2273 loff_t offset, unsigned long nr_segs)
2274{
2275 struct file *file = iocb->ki_filp;
2276 struct address_space *mapping = file->f_mapping;
2277 ssize_t retval;
2278 size_t write_len = 0;
2279
2280 /*
2281 * If it's a write, unmap all mmappings of the file up-front. This
2282 * will cause any pte dirty bits to be propagated into the pageframes
2283 * for the subsequent filemap_write_and_wait().
2284 */
2285 if (rw == WRITE) {
2286 write_len = iov_length(iov, nr_segs);
2287 if (mapping_mapped(mapping))
2288 unmap_mapping_range(mapping, offset, write_len, 0);
2289 }
2290
2291 retval = filemap_write_and_wait(mapping);
2292 if (retval == 0) {
2293 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2294 offset, nr_segs);
2295 if (rw == WRITE && mapping->nrpages) {
2296 pgoff_t end = (offset + write_len - 1)
2297 >> PAGE_CACHE_SHIFT;
2298 int err = invalidate_inode_pages2_range(mapping,
2299 offset >> PAGE_CACHE_SHIFT, end);
2300 if (err)
2301 retval = err;
2302 }
2303 }
2304 return retval;
2305}
2306EXPORT_SYMBOL_GPL(generic_file_direct_IO);
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-14 22:54:33 -0500