[PATCH] fix for __generic_file_aio_read() to return 0 on EOF
[linux-2.6.git] / mm / filemap.c
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  * FIXME: remove all knowledge of the buffer layer from the core VM
33  */
34 #include <linux/buffer_head.h> /* for generic_osync_inode */
35
36 #include <asm/uaccess.h>
37 #include <asm/mman.h>
38
39 /*
40  * Shared mappings implemented 30.11.1994. It's not fully working yet,
41  * though.
42  *
43  * Shared mappings now work. 15.8.1995  Bruno.
44  *
45  * finished 'unifying' the page and buffer cache and SMP-threaded the
46  * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
47  *
48  * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
49  */
50
51 /*
52  * Lock ordering:
53  *
54  *  ->i_mmap_lock               (vmtruncate)
55  *    ->private_lock            (__free_pte->__set_page_dirty_buffers)
56  *      ->swap_list_lock
57  *        ->swap_device_lock    (exclusive_swap_page, others)
58  *          ->mapping->tree_lock
59  *
60  *  ->i_sem
61  *    ->i_mmap_lock             (truncate->unmap_mapping_range)
62  *
63  *  ->mmap_sem
64  *    ->i_mmap_lock
65  *      ->page_table_lock       (various places, mainly in mmap.c)
66  *        ->mapping->tree_lock  (arch-dependent flush_dcache_mmap_lock)
67  *
68  *  ->mmap_sem
69  *    ->lock_page               (access_process_vm)
70  *
71  *  ->mmap_sem
72  *    ->i_sem                   (msync)
73  *
74  *  ->i_sem
75  *    ->i_alloc_sem             (various)
76  *
77  *  ->inode_lock
78  *    ->sb_lock                 (fs/fs-writeback.c)
79  *    ->mapping->tree_lock      (__sync_single_inode)
80  *
81  *  ->i_mmap_lock
82  *    ->anon_vma.lock           (vma_adjust)
83  *
84  *  ->anon_vma.lock
85  *    ->page_table_lock         (anon_vma_prepare and various)
86  *
87  *  ->page_table_lock
88  *    ->swap_device_lock        (try_to_unmap_one)
89  *    ->private_lock            (try_to_unmap_one)
90  *    ->tree_lock               (try_to_unmap_one)
91  *    ->zone.lru_lock           (follow_page->mark_page_accessed)
92  *    ->private_lock            (page_remove_rmap->set_page_dirty)
93  *    ->tree_lock               (page_remove_rmap->set_page_dirty)
94  *    ->inode_lock              (page_remove_rmap->set_page_dirty)
95  *    ->inode_lock              (zap_pte_range->set_page_dirty)
96  *    ->private_lock            (zap_pte_range->__set_page_dirty_buffers)
97  *
98  *  ->task->proc_lock
99  *    ->dcache_lock             (proc_pid_lookup)
100  */
101
102 /*
103  * Remove a page from the page cache and free it. Caller has to make
104  * sure the page is locked and that nobody else uses it - or that usage
105  * is safe.  The caller must hold a write_lock on the mapping's tree_lock.
106  */
107 void __remove_from_page_cache(struct page *page)
108 {
109         struct address_space *mapping = page->mapping;
110
111         radix_tree_delete(&mapping->page_tree, page->index);
112         page->mapping = NULL;
113         mapping->nrpages--;
114         pagecache_acct(-1);
115 }
116
117 void remove_from_page_cache(struct page *page)
118 {
119         struct address_space *mapping = page->mapping;
120
121         BUG_ON(!PageLocked(page));
122
123         write_lock_irq(&mapping->tree_lock);
124         __remove_from_page_cache(page);
125         write_unlock_irq(&mapping->tree_lock);
126 }
127
128 static int sync_page(void *word)
129 {
130         struct address_space *mapping;
131         struct page *page;
132
133         page = container_of((page_flags_t *)word, struct page, flags);
134
135         /*
136          * page_mapping() is being called without PG_locked held.
137          * Some knowledge of the state and use of the page is used to
138          * reduce the requirements down to a memory barrier.
139          * The danger here is of a stale page_mapping() return value
140          * indicating a struct address_space different from the one it's
141          * associated with when it is associated with one.
142          * After smp_mb(), it's either the correct page_mapping() for
143          * the page, or an old page_mapping() and the page's own
144          * page_mapping() has gone NULL.
145          * The ->sync_page() address_space operation must tolerate
146          * page_mapping() going NULL. By an amazing coincidence,
147          * this comes about because none of the users of the page
148          * in the ->sync_page() methods make essential use of the
149          * page_mapping(), merely passing the page down to the backing
150          * device's unplug functions when it's non-NULL, which in turn
151          * ignore it for all cases but swap, where only page->private is
152          * of interest. When page_mapping() does go NULL, the entire
153          * call stack gracefully ignores the page and returns.
154          * -- wli
155          */
156         smp_mb();
157         mapping = page_mapping(page);
158         if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
159                 mapping->a_ops->sync_page(page);
160         io_schedule();
161         return 0;
162 }
163
164 /**
165  * filemap_fdatawrite_range - start writeback against all of a mapping's
166  * dirty pages that lie within the byte offsets <start, end>
167  * @mapping:    address space structure to write
168  * @start:      offset in bytes where the range starts
169  * @end:        offset in bytes where the range ends
170  * @sync_mode:  enable synchronous operation
171  *
172  * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
173  * opposed to a regular memory * cleansing writeback.  The difference between
174  * these two operations is that if a dirty page/buffer is encountered, it must
175  * be waited upon, and not just skipped over.
176  */
177 static int __filemap_fdatawrite_range(struct address_space *mapping,
178         loff_t start, loff_t end, int sync_mode)
179 {
180         int ret;
181         struct writeback_control wbc = {
182                 .sync_mode = sync_mode,
183                 .nr_to_write = mapping->nrpages * 2,
184                 .start = start,
185                 .end = end,
186         };
187
188         if (!mapping_cap_writeback_dirty(mapping))
189                 return 0;
190
191         ret = do_writepages(mapping, &wbc);
192         return ret;
193 }
194
195 static inline int __filemap_fdatawrite(struct address_space *mapping,
196         int sync_mode)
197 {
198         return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
199 }
200
201 int filemap_fdatawrite(struct address_space *mapping)
202 {
203         return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
204 }
205 EXPORT_SYMBOL(filemap_fdatawrite);
206
207 static int filemap_fdatawrite_range(struct address_space *mapping,
208         loff_t start, loff_t end)
209 {
210         return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
211 }
212
213 /*
214  * This is a mostly non-blocking flush.  Not suitable for data-integrity
215  * purposes - I/O may not be started against all dirty pages.
216  */
217 int filemap_flush(struct address_space *mapping)
218 {
219         return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
220 }
221 EXPORT_SYMBOL(filemap_flush);
222
223 /*
224  * Wait for writeback to complete against pages indexed by start->end
225  * inclusive
226  */
227 static int wait_on_page_writeback_range(struct address_space *mapping,
228                                 pgoff_t start, pgoff_t end)
229 {
230         struct pagevec pvec;
231         int nr_pages;
232         int ret = 0;
233         pgoff_t index;
234
235         if (end < start)
236                 return 0;
237
238         pagevec_init(&pvec, 0);
239         index = start;
240         while ((index <= end) &&
241                         (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
242                         PAGECACHE_TAG_WRITEBACK,
243                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
244                 unsigned i;
245
246                 for (i = 0; i < nr_pages; i++) {
247                         struct page *page = pvec.pages[i];
248
249                         /* until radix tree lookup accepts end_index */
250                         if (page->index > end)
251                                 continue;
252
253                         wait_on_page_writeback(page);
254                         if (PageError(page))
255                                 ret = -EIO;
256                 }
257                 pagevec_release(&pvec);
258                 cond_resched();
259         }
260
261         /* Check for outstanding write errors */
262         if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
263                 ret = -ENOSPC;
264         if (test_and_clear_bit(AS_EIO, &mapping->flags))
265                 ret = -EIO;
266
267         return ret;
268 }
269
270 /*
271  * Write and wait upon all the pages in the passed range.  This is a "data
272  * integrity" operation.  It waits upon in-flight writeout before starting and
273  * waiting upon new writeout.  If there was an IO error, return it.
274  *
275  * We need to re-take i_sem during the generic_osync_inode list walk because
276  * it is otherwise livelockable.
277  */
278 int sync_page_range(struct inode *inode, struct address_space *mapping,
279                         loff_t pos, size_t count)
280 {
281         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
282         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
283         int ret;
284
285         if (!mapping_cap_writeback_dirty(mapping) || !count)
286                 return 0;
287         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
288         if (ret == 0) {
289                 down(&inode->i_sem);
290                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
291                 up(&inode->i_sem);
292         }
293         if (ret == 0)
294                 ret = wait_on_page_writeback_range(mapping, start, end);
295         return ret;
296 }
297 EXPORT_SYMBOL(sync_page_range);
298
299 /*
300  * Note: Holding i_sem across sync_page_range_nolock is not a good idea
301  * as it forces O_SYNC writers to different parts of the same file
302  * to be serialised right until io completion.
303  */
304 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
305                         loff_t pos, size_t count)
306 {
307         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
308         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
309         int ret;
310
311         if (!mapping_cap_writeback_dirty(mapping) || !count)
312                 return 0;
313         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
314         if (ret == 0)
315                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
316         if (ret == 0)
317                 ret = wait_on_page_writeback_range(mapping, start, end);
318         return ret;
319 }
320 EXPORT_SYMBOL(sync_page_range_nolock);
321
322 /**
323  * filemap_fdatawait - walk the list of under-writeback pages of the given
324  *     address space and wait for all of them.
325  *
326  * @mapping: address space structure to wait for
327  */
328 int filemap_fdatawait(struct address_space *mapping)
329 {
330         loff_t i_size = i_size_read(mapping->host);
331
332         if (i_size == 0)
333                 return 0;
334
335         return wait_on_page_writeback_range(mapping, 0,
336                                 (i_size - 1) >> PAGE_CACHE_SHIFT);
337 }
338 EXPORT_SYMBOL(filemap_fdatawait);
339
340 int filemap_write_and_wait(struct address_space *mapping)
341 {
342         int retval = 0;
343
344         if (mapping->nrpages) {
345                 retval = filemap_fdatawrite(mapping);
346                 if (retval == 0)
347                         retval = filemap_fdatawait(mapping);
348         }
349         return retval;
350 }
351
352 int filemap_write_and_wait_range(struct address_space *mapping,
353                                  loff_t lstart, loff_t lend)
354 {
355         int retval = 0;
356
357         if (mapping->nrpages) {
358                 retval = __filemap_fdatawrite_range(mapping, lstart, lend,
359                                                     WB_SYNC_ALL);
360                 if (retval == 0)
361                         retval = wait_on_page_writeback_range(mapping,
362                                                     lstart >> PAGE_CACHE_SHIFT,
363                                                     lend >> PAGE_CACHE_SHIFT);
364         }
365         return retval;
366 }
367
368 /*
369  * This function is used to add newly allocated pagecache pages:
370  * the page is new, so we can just run SetPageLocked() against it.
371  * The other page state flags were set by rmqueue().
372  *
373  * This function does not add the page to the LRU.  The caller must do that.
374  */
375 int add_to_page_cache(struct page *page, struct address_space *mapping,
376                 pgoff_t offset, int gfp_mask)
377 {
378         int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
379
380         if (error == 0) {
381                 write_lock_irq(&mapping->tree_lock);
382                 error = radix_tree_insert(&mapping->page_tree, offset, page);
383                 if (!error) {
384                         page_cache_get(page);
385                         SetPageLocked(page);
386                         page->mapping = mapping;
387                         page->index = offset;
388                         mapping->nrpages++;
389                         pagecache_acct(1);
390                 }
391                 write_unlock_irq(&mapping->tree_lock);
392                 radix_tree_preload_end();
393         }
394         return error;
395 }
396
397 EXPORT_SYMBOL(add_to_page_cache);
398
399 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
400                                 pgoff_t offset, int gfp_mask)
401 {
402         int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
403         if (ret == 0)
404                 lru_cache_add(page);
405         return ret;
406 }
407
408 /*
409  * In order to wait for pages to become available there must be
410  * waitqueues associated with pages. By using a hash table of
411  * waitqueues where the bucket discipline is to maintain all
412  * waiters on the same queue and wake all when any of the pages
413  * become available, and for the woken contexts to check to be
414  * sure the appropriate page became available, this saves space
415  * at a cost of "thundering herd" phenomena during rare hash
416  * collisions.
417  */
418 static wait_queue_head_t *page_waitqueue(struct page *page)
419 {
420         const struct zone *zone = page_zone(page);
421
422         return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
423 }
424
425 static inline void wake_up_page(struct page *page, int bit)
426 {
427         __wake_up_bit(page_waitqueue(page), &page->flags, bit);
428 }
429
430 void fastcall wait_on_page_bit(struct page *page, int bit_nr)
431 {
432         DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
433
434         if (test_bit(bit_nr, &page->flags))
435                 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
436                                                         TASK_UNINTERRUPTIBLE);
437 }
438 EXPORT_SYMBOL(wait_on_page_bit);
439
440 /**
441  * unlock_page() - unlock a locked page
442  *
443  * @page: the page
444  *
445  * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
446  * Also wakes sleepers in wait_on_page_writeback() because the wakeup
447  * mechananism between PageLocked pages and PageWriteback pages is shared.
448  * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
449  *
450  * The first mb is necessary to safely close the critical section opened by the
451  * TestSetPageLocked(), the second mb is necessary to enforce ordering between
452  * the clear_bit and the read of the waitqueue (to avoid SMP races with a
453  * parallel wait_on_page_locked()).
454  */
455 void fastcall unlock_page(struct page *page)
456 {
457         smp_mb__before_clear_bit();
458         if (!TestClearPageLocked(page))
459                 BUG();
460         smp_mb__after_clear_bit(); 
461         wake_up_page(page, PG_locked);
462 }
463 EXPORT_SYMBOL(unlock_page);
464
465 /*
466  * End writeback against a page.
467  */
468 void end_page_writeback(struct page *page)
469 {
470         if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
471                 if (!test_clear_page_writeback(page))
472                         BUG();
473         }
474         smp_mb__after_clear_bit();
475         wake_up_page(page, PG_writeback);
476 }
477 EXPORT_SYMBOL(end_page_writeback);
478
479 /*
480  * Get a lock on the page, assuming we need to sleep to get it.
481  *
482  * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary.  If some
483  * random driver's requestfn sets TASK_RUNNING, we could busywait.  However
484  * chances are that on the second loop, the block layer's plug list is empty,
485  * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
486  */
487 void fastcall __lock_page(struct page *page)
488 {
489         DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
490
491         __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
492                                                         TASK_UNINTERRUPTIBLE);
493 }
494 EXPORT_SYMBOL(__lock_page);
495
496 /*
497  * a rather lightweight function, finding and getting a reference to a
498  * hashed page atomically.
499  */
500 struct page * find_get_page(struct address_space *mapping, unsigned long offset)
501 {
502         struct page *page;
503
504         read_lock_irq(&mapping->tree_lock);
505         page = radix_tree_lookup(&mapping->page_tree, offset);
506         if (page)
507                 page_cache_get(page);
508         read_unlock_irq(&mapping->tree_lock);
509         return page;
510 }
511
512 EXPORT_SYMBOL(find_get_page);
513
514 /*
515  * Same as above, but trylock it instead of incrementing the count.
516  */
517 struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
518 {
519         struct page *page;
520
521         read_lock_irq(&mapping->tree_lock);
522         page = radix_tree_lookup(&mapping->page_tree, offset);
523         if (page && TestSetPageLocked(page))
524                 page = NULL;
525         read_unlock_irq(&mapping->tree_lock);
526         return page;
527 }
528
529 EXPORT_SYMBOL(find_trylock_page);
530
531 /**
532  * find_lock_page - locate, pin and lock a pagecache page
533  *
534  * @mapping: the address_space to search
535  * @offset: the page index
536  *
537  * Locates the desired pagecache page, locks it, increments its reference
538  * count and returns its address.
539  *
540  * Returns zero if the page was not present. find_lock_page() may sleep.
541  */
542 struct page *find_lock_page(struct address_space *mapping,
543                                 unsigned long offset)
544 {
545         struct page *page;
546
547         read_lock_irq(&mapping->tree_lock);
548 repeat:
549         page = radix_tree_lookup(&mapping->page_tree, offset);
550         if (page) {
551                 page_cache_get(page);
552                 if (TestSetPageLocked(page)) {
553                         read_unlock_irq(&mapping->tree_lock);
554                         lock_page(page);
555                         read_lock_irq(&mapping->tree_lock);
556
557                         /* Has the page been truncated while we slept? */
558                         if (page->mapping != mapping || page->index != offset) {
559                                 unlock_page(page);
560                                 page_cache_release(page);
561                                 goto repeat;
562                         }
563                 }
564         }
565         read_unlock_irq(&mapping->tree_lock);
566         return page;
567 }
568
569 EXPORT_SYMBOL(find_lock_page);
570
571 /**
572  * find_or_create_page - locate or add a pagecache page
573  *
574  * @mapping: the page's address_space
575  * @index: the page's index into the mapping
576  * @gfp_mask: page allocation mode
577  *
578  * Locates a page in the pagecache.  If the page is not present, a new page
579  * is allocated using @gfp_mask and is added to the pagecache and to the VM's
580  * LRU list.  The returned page is locked and has its reference count
581  * incremented.
582  *
583  * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
584  * allocation!
585  *
586  * find_or_create_page() returns the desired page's address, or zero on
587  * memory exhaustion.
588  */
589 struct page *find_or_create_page(struct address_space *mapping,
590                 unsigned long index, unsigned int gfp_mask)
591 {
592         struct page *page, *cached_page = NULL;
593         int err;
594 repeat:
595         page = find_lock_page(mapping, index);
596         if (!page) {
597                 if (!cached_page) {
598                         cached_page = alloc_page(gfp_mask);
599                         if (!cached_page)
600                                 return NULL;
601                 }
602                 err = add_to_page_cache_lru(cached_page, mapping,
603                                         index, gfp_mask);
604                 if (!err) {
605                         page = cached_page;
606                         cached_page = NULL;
607                 } else if (err == -EEXIST)
608                         goto repeat;
609         }
610         if (cached_page)
611                 page_cache_release(cached_page);
612         return page;
613 }
614
615 EXPORT_SYMBOL(find_or_create_page);
616
617 /**
618  * find_get_pages - gang pagecache lookup
619  * @mapping:    The address_space to search
620  * @start:      The starting page index
621  * @nr_pages:   The maximum number of pages
622  * @pages:      Where the resulting pages are placed
623  *
624  * find_get_pages() will search for and return a group of up to
625  * @nr_pages pages in the mapping.  The pages are placed at @pages.
626  * find_get_pages() takes a reference against the returned pages.
627  *
628  * The search returns a group of mapping-contiguous pages with ascending
629  * indexes.  There may be holes in the indices due to not-present pages.
630  *
631  * find_get_pages() returns the number of pages which were found.
632  */
633 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
634                             unsigned int nr_pages, struct page **pages)
635 {
636         unsigned int i;
637         unsigned int ret;
638
639         read_lock_irq(&mapping->tree_lock);
640         ret = radix_tree_gang_lookup(&mapping->page_tree,
641                                 (void **)pages, start, nr_pages);
642         for (i = 0; i < ret; i++)
643                 page_cache_get(pages[i]);
644         read_unlock_irq(&mapping->tree_lock);
645         return ret;
646 }
647
648 /*
649  * Like find_get_pages, except we only return pages which are tagged with
650  * `tag'.   We update *index to index the next page for the traversal.
651  */
652 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
653                         int tag, unsigned int nr_pages, struct page **pages)
654 {
655         unsigned int i;
656         unsigned int ret;
657
658         read_lock_irq(&mapping->tree_lock);
659         ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
660                                 (void **)pages, *index, nr_pages, tag);
661         for (i = 0; i < ret; i++)
662                 page_cache_get(pages[i]);
663         if (ret)
664                 *index = pages[ret - 1]->index + 1;
665         read_unlock_irq(&mapping->tree_lock);
666         return ret;
667 }
668
669 /*
670  * Same as grab_cache_page, but do not wait if the page is unavailable.
671  * This is intended for speculative data generators, where the data can
672  * be regenerated if the page couldn't be grabbed.  This routine should
673  * be safe to call while holding the lock for another page.
674  *
675  * Clear __GFP_FS when allocating the page to avoid recursion into the fs
676  * and deadlock against the caller's locked page.
677  */
678 struct page *
679 grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
680 {
681         struct page *page = find_get_page(mapping, index);
682         unsigned int gfp_mask;
683
684         if (page) {
685                 if (!TestSetPageLocked(page))
686                         return page;
687                 page_cache_release(page);
688                 return NULL;
689         }
690         gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
691         page = alloc_pages(gfp_mask, 0);
692         if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
693                 page_cache_release(page);
694                 page = NULL;
695         }
696         return page;
697 }
698
699 EXPORT_SYMBOL(grab_cache_page_nowait);
700
701 /*
702  * This is a generic file read routine, and uses the
703  * mapping->a_ops->readpage() function for the actual low-level
704  * stuff.
705  *
706  * This is really ugly. But the goto's actually try to clarify some
707  * of the logic when it comes to error handling etc.
708  *
709  * Note the struct file* is only passed for the use of readpage.  It may be
710  * NULL.
711  */
712 void do_generic_mapping_read(struct address_space *mapping,
713                              struct file_ra_state *_ra,
714                              struct file *filp,
715                              loff_t *ppos,
716                              read_descriptor_t *desc,
717                              read_actor_t actor)
718 {
719         struct inode *inode = mapping->host;
720         unsigned long index;
721         unsigned long end_index;
722         unsigned long offset;
723         unsigned long last_index;
724         unsigned long next_index;
725         unsigned long prev_index;
726         loff_t isize;
727         struct page *cached_page;
728         int error;
729         struct file_ra_state ra = *_ra;
730
731         cached_page = NULL;
732         index = *ppos >> PAGE_CACHE_SHIFT;
733         next_index = index;
734         prev_index = ra.prev_page;
735         last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
736         offset = *ppos & ~PAGE_CACHE_MASK;
737
738         isize = i_size_read(inode);
739         if (!isize)
740                 goto out;
741
742         end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
743         for (;;) {
744                 struct page *page;
745                 unsigned long nr, ret;
746
747                 /* nr is the maximum number of bytes to copy from this page */
748                 nr = PAGE_CACHE_SIZE;
749                 if (index >= end_index) {
750                         if (index > end_index)
751                                 goto out;
752                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
753                         if (nr <= offset) {
754                                 goto out;
755                         }
756                 }
757                 nr = nr - offset;
758
759                 cond_resched();
760                 if (index == next_index)
761                         next_index = page_cache_readahead(mapping, &ra, filp,
762                                         index, last_index - index);
763
764 find_page:
765                 page = find_get_page(mapping, index);
766                 if (unlikely(page == NULL)) {
767                         handle_ra_miss(mapping, &ra, index);
768                         goto no_cached_page;
769                 }
770                 if (!PageUptodate(page))
771                         goto page_not_up_to_date;
772 page_ok:
773
774                 /* If users can be writing to this page using arbitrary
775                  * virtual addresses, take care about potential aliasing
776                  * before reading the page on the kernel side.
777                  */
778                 if (mapping_writably_mapped(mapping))
779                         flush_dcache_page(page);
780
781                 /*
782                  * When (part of) the same page is read multiple times
783                  * in succession, only mark it as accessed the first time.
784                  */
785                 if (prev_index != index)
786                         mark_page_accessed(page);
787                 prev_index = index;
788
789                 /*
790                  * Ok, we have the page, and it's up-to-date, so
791                  * now we can copy it to user space...
792                  *
793                  * The actor routine returns how many bytes were actually used..
794                  * NOTE! This may not be the same as how much of a user buffer
795                  * we filled up (we may be padding etc), so we can only update
796                  * "pos" here (the actor routine has to update the user buffer
797                  * pointers and the remaining count).
798                  */
799                 ret = actor(desc, page, offset, nr);
800                 offset += ret;
801                 index += offset >> PAGE_CACHE_SHIFT;
802                 offset &= ~PAGE_CACHE_MASK;
803
804                 page_cache_release(page);
805                 if (ret == nr && desc->count)
806                         continue;
807                 goto out;
808
809 page_not_up_to_date:
810                 /* Get exclusive access to the page ... */
811                 lock_page(page);
812
813                 /* Did it get unhashed before we got the lock? */
814                 if (!page->mapping) {
815                         unlock_page(page);
816                         page_cache_release(page);
817                         continue;
818                 }
819
820                 /* Did somebody else fill it already? */
821                 if (PageUptodate(page)) {
822                         unlock_page(page);
823                         goto page_ok;
824                 }
825
826 readpage:
827                 /* Start the actual read. The read will unlock the page. */
828                 error = mapping->a_ops->readpage(filp, page);
829
830                 if (unlikely(error))
831                         goto readpage_error;
832
833                 if (!PageUptodate(page)) {
834                         lock_page(page);
835                         if (!PageUptodate(page)) {
836                                 if (page->mapping == NULL) {
837                                         /*
838                                          * invalidate_inode_pages got it
839                                          */
840                                         unlock_page(page);
841                                         page_cache_release(page);
842                                         goto find_page;
843                                 }
844                                 unlock_page(page);
845                                 error = -EIO;
846                                 goto readpage_error;
847                         }
848                         unlock_page(page);
849                 }
850
851                 /*
852                  * i_size must be checked after we have done ->readpage.
853                  *
854                  * Checking i_size after the readpage allows us to calculate
855                  * the correct value for "nr", which means the zero-filled
856                  * part of the page is not copied back to userspace (unless
857                  * another truncate extends the file - this is desired though).
858                  */
859                 isize = i_size_read(inode);
860                 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
861                 if (unlikely(!isize || index > end_index)) {
862                         page_cache_release(page);
863                         goto out;
864                 }
865
866                 /* nr is the maximum number of bytes to copy from this page */
867                 nr = PAGE_CACHE_SIZE;
868                 if (index == end_index) {
869                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
870                         if (nr <= offset) {
871                                 page_cache_release(page);
872                                 goto out;
873                         }
874                 }
875                 nr = nr - offset;
876                 goto page_ok;
877
878 readpage_error:
879                 /* UHHUH! A synchronous read error occurred. Report it */
880                 desc->error = error;
881                 page_cache_release(page);
882                 goto out;
883
884 no_cached_page:
885                 /*
886                  * Ok, it wasn't cached, so we need to create a new
887                  * page..
888                  */
889                 if (!cached_page) {
890                         cached_page = page_cache_alloc_cold(mapping);
891                         if (!cached_page) {
892                                 desc->error = -ENOMEM;
893                                 goto out;
894                         }
895                 }
896                 error = add_to_page_cache_lru(cached_page, mapping,
897                                                 index, GFP_KERNEL);
898                 if (error) {
899                         if (error == -EEXIST)
900                                 goto find_page;
901                         desc->error = error;
902                         goto out;
903                 }
904                 page = cached_page;
905                 cached_page = NULL;
906                 goto readpage;
907         }
908
909 out:
910         *_ra = ra;
911
912         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
913         if (cached_page)
914                 page_cache_release(cached_page);
915         if (filp)
916                 file_accessed(filp);
917 }
918
919 EXPORT_SYMBOL(do_generic_mapping_read);
920
921 int file_read_actor(read_descriptor_t *desc, struct page *page,
922                         unsigned long offset, unsigned long size)
923 {
924         char *kaddr;
925         unsigned long left, count = desc->count;
926
927         if (size > count)
928                 size = count;
929
930         /*
931          * Faults on the destination of a read are common, so do it before
932          * taking the kmap.
933          */
934         if (!fault_in_pages_writeable(desc->arg.buf, size)) {
935                 kaddr = kmap_atomic(page, KM_USER0);
936                 left = __copy_to_user_inatomic(desc->arg.buf,
937                                                 kaddr + offset, size);
938                 kunmap_atomic(kaddr, KM_USER0);
939                 if (left == 0)
940                         goto success;
941         }
942
943         /* Do it the slow way */
944         kaddr = kmap(page);
945         left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
946         kunmap(page);
947
948         if (left) {
949                 size -= left;
950                 desc->error = -EFAULT;
951         }
952 success:
953         desc->count = count - size;
954         desc->written += size;
955         desc->arg.buf += size;
956         return size;
957 }
958
959 /*
960  * This is the "read()" routine for all filesystems
961  * that can use the page cache directly.
962  */
963 ssize_t
964 __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
965                 unsigned long nr_segs, loff_t *ppos)
966 {
967         struct file *filp = iocb->ki_filp;
968         ssize_t retval;
969         unsigned long seg;
970         size_t count;
971
972         count = 0;
973         for (seg = 0; seg < nr_segs; seg++) {
974                 const struct iovec *iv = &iov[seg];
975
976                 /*
977                  * If any segment has a negative length, or the cumulative
978                  * length ever wraps negative then return -EINVAL.
979                  */
980                 count += iv->iov_len;
981                 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
982                         return -EINVAL;
983                 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
984                         continue;
985                 if (seg == 0)
986                         return -EFAULT;
987                 nr_segs = seg;
988                 count -= iv->iov_len;   /* This segment is no good */
989                 break;
990         }
991
992         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
993         if (filp->f_flags & O_DIRECT) {
994                 loff_t pos = *ppos, size;
995                 struct address_space *mapping;
996                 struct inode *inode;
997
998                 mapping = filp->f_mapping;
999                 inode = mapping->host;
1000                 retval = 0;
1001                 if (!count)
1002                         goto out; /* skip atime */
1003                 size = i_size_read(inode);
1004                 if (pos < size) {
1005                         retval = generic_file_direct_IO(READ, iocb,
1006                                                 iov, pos, nr_segs);
1007                         if (retval > 0 && !is_sync_kiocb(iocb))
1008                                 retval = -EIOCBQUEUED;
1009                         if (retval > 0)
1010                                 *ppos = pos + retval;
1011                 }
1012                 file_accessed(filp);
1013                 goto out;
1014         }
1015
1016         retval = 0;
1017         if (count) {
1018                 for (seg = 0; seg < nr_segs; seg++) {
1019                         read_descriptor_t desc;
1020
1021                         desc.written = 0;
1022                         desc.arg.buf = iov[seg].iov_base;
1023                         desc.count = iov[seg].iov_len;
1024                         if (desc.count == 0)
1025                                 continue;
1026                         desc.error = 0;
1027                         do_generic_file_read(filp,ppos,&desc,file_read_actor);
1028                         retval += desc.written;
1029                         if (!retval) {
1030                                 retval = desc.error;
1031                                 break;
1032                         }
1033                 }
1034         }
1035 out:
1036         return retval;
1037 }
1038
1039 EXPORT_SYMBOL(__generic_file_aio_read);
1040
1041 ssize_t
1042 generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1043 {
1044         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1045
1046         BUG_ON(iocb->ki_pos != pos);
1047         return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1048 }
1049
1050 EXPORT_SYMBOL(generic_file_aio_read);
1051
1052 ssize_t
1053 generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1054 {
1055         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1056         struct kiocb kiocb;
1057         ssize_t ret;
1058
1059         init_sync_kiocb(&kiocb, filp);
1060         ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1061         if (-EIOCBQUEUED == ret)
1062                 ret = wait_on_sync_kiocb(&kiocb);
1063         return ret;
1064 }
1065
1066 EXPORT_SYMBOL(generic_file_read);
1067
1068 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1069 {
1070         ssize_t written;
1071         unsigned long count = desc->count;
1072         struct file *file = desc->arg.data;
1073
1074         if (size > count)
1075                 size = count;
1076
1077         written = file->f_op->sendpage(file, page, offset,
1078                                        size, &file->f_pos, size<count);
1079         if (written < 0) {
1080                 desc->error = written;
1081                 written = 0;
1082         }
1083         desc->count = count - written;
1084         desc->written += written;
1085         return written;
1086 }
1087
1088 ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1089                          size_t count, read_actor_t actor, void *target)
1090 {
1091         read_descriptor_t desc;
1092
1093         if (!count)
1094                 return 0;
1095
1096         desc.written = 0;
1097         desc.count = count;
1098         desc.arg.data = target;
1099         desc.error = 0;
1100
1101         do_generic_file_read(in_file, ppos, &desc, actor);
1102         if (desc.written)
1103                 return desc.written;
1104         return desc.error;
1105 }
1106
1107 EXPORT_SYMBOL(generic_file_sendfile);
1108
1109 static ssize_t
1110 do_readahead(struct address_space *mapping, struct file *filp,
1111              unsigned long index, unsigned long nr)
1112 {
1113         if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1114                 return -EINVAL;
1115
1116         force_page_cache_readahead(mapping, filp, index,
1117                                         max_sane_readahead(nr));
1118         return 0;
1119 }
1120
1121 asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1122 {
1123         ssize_t ret;
1124         struct file *file;
1125
1126         ret = -EBADF;
1127         file = fget(fd);
1128         if (file) {
1129                 if (file->f_mode & FMODE_READ) {
1130                         struct address_space *mapping = file->f_mapping;
1131                         unsigned long start = offset >> PAGE_CACHE_SHIFT;
1132                         unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1133                         unsigned long len = end - start + 1;
1134                         ret = do_readahead(mapping, file, start, len);
1135                 }
1136                 fput(file);
1137         }
1138         return ret;
1139 }
1140
1141 #ifdef CONFIG_MMU
1142 /*
1143  * This adds the requested page to the page cache if it isn't already there,
1144  * and schedules an I/O to read in its contents from disk.
1145  */
1146 static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1147 static int fastcall page_cache_read(struct file * file, unsigned long offset)
1148 {
1149         struct address_space *mapping = file->f_mapping;
1150         struct page *page; 
1151         int error;
1152
1153         page = page_cache_alloc_cold(mapping);
1154         if (!page)
1155                 return -ENOMEM;
1156
1157         error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1158         if (!error) {
1159                 error = mapping->a_ops->readpage(file, page);
1160                 page_cache_release(page);
1161                 return error;
1162         }
1163
1164         /*
1165          * We arrive here in the unlikely event that someone 
1166          * raced with us and added our page to the cache first
1167          * or we are out of memory for radix-tree nodes.
1168          */
1169         page_cache_release(page);
1170         return error == -EEXIST ? 0 : error;
1171 }
1172
1173 #define MMAP_LOTSAMISS  (100)
1174
1175 /*
1176  * filemap_nopage() is invoked via the vma operations vector for a
1177  * mapped memory region to read in file data during a page fault.
1178  *
1179  * The goto's are kind of ugly, but this streamlines the normal case of having
1180  * it in the page cache, and handles the special cases reasonably without
1181  * having a lot of duplicated code.
1182  */
1183 struct page *filemap_nopage(struct vm_area_struct *area,
1184                                 unsigned long address, int *type)
1185 {
1186         int error;
1187         struct file *file = area->vm_file;
1188         struct address_space *mapping = file->f_mapping;
1189         struct file_ra_state *ra = &file->f_ra;
1190         struct inode *inode = mapping->host;
1191         struct page *page;
1192         unsigned long size, pgoff;
1193         int did_readaround = 0, majmin = VM_FAULT_MINOR;
1194
1195         pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1196
1197 retry_all:
1198         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1199         if (pgoff >= size)
1200                 goto outside_data_content;
1201
1202         /* If we don't want any read-ahead, don't bother */
1203         if (VM_RandomReadHint(area))
1204                 goto no_cached_page;
1205
1206         /*
1207          * The readahead code wants to be told about each and every page
1208          * so it can build and shrink its windows appropriately
1209          *
1210          * For sequential accesses, we use the generic readahead logic.
1211          */
1212         if (VM_SequentialReadHint(area))
1213                 page_cache_readahead(mapping, ra, file, pgoff, 1);
1214
1215         /*
1216          * Do we have something in the page cache already?
1217          */
1218 retry_find:
1219         page = find_get_page(mapping, pgoff);
1220         if (!page) {
1221                 unsigned long ra_pages;
1222
1223                 if (VM_SequentialReadHint(area)) {
1224                         handle_ra_miss(mapping, ra, pgoff);
1225                         goto no_cached_page;
1226                 }
1227                 ra->mmap_miss++;
1228
1229                 /*
1230                  * Do we miss much more than hit in this file? If so,
1231                  * stop bothering with read-ahead. It will only hurt.
1232                  */
1233                 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1234                         goto no_cached_page;
1235
1236                 /*
1237                  * To keep the pgmajfault counter straight, we need to
1238                  * check did_readaround, as this is an inner loop.
1239                  */
1240                 if (!did_readaround) {
1241                         majmin = VM_FAULT_MAJOR;
1242                         inc_page_state(pgmajfault);
1243                 }
1244                 did_readaround = 1;
1245                 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1246                 if (ra_pages) {
1247                         pgoff_t start = 0;
1248
1249                         if (pgoff > ra_pages / 2)
1250                                 start = pgoff - ra_pages / 2;
1251                         do_page_cache_readahead(mapping, file, start, ra_pages);
1252                 }
1253                 page = find_get_page(mapping, pgoff);
1254                 if (!page)
1255                         goto no_cached_page;
1256         }
1257
1258         if (!did_readaround)
1259                 ra->mmap_hit++;
1260
1261         /*
1262          * Ok, found a page in the page cache, now we need to check
1263          * that it's up-to-date.
1264          */
1265         if (!PageUptodate(page))
1266                 goto page_not_uptodate;
1267
1268 success:
1269         /*
1270          * Found the page and have a reference on it.
1271          */
1272         mark_page_accessed(page);
1273         if (type)
1274                 *type = majmin;
1275         return page;
1276
1277 outside_data_content:
1278         /*
1279          * An external ptracer can access pages that normally aren't
1280          * accessible..
1281          */
1282         if (area->vm_mm == current->mm)
1283                 return NULL;
1284         /* Fall through to the non-read-ahead case */
1285 no_cached_page:
1286         /*
1287          * We're only likely to ever get here if MADV_RANDOM is in
1288          * effect.
1289          */
1290         error = page_cache_read(file, pgoff);
1291         grab_swap_token();
1292
1293         /*
1294          * The page we want has now been added to the page cache.
1295          * In the unlikely event that someone removed it in the
1296          * meantime, we'll just come back here and read it again.
1297          */
1298         if (error >= 0)
1299                 goto retry_find;
1300
1301         /*
1302          * An error return from page_cache_read can result if the
1303          * system is low on memory, or a problem occurs while trying
1304          * to schedule I/O.
1305          */
1306         if (error == -ENOMEM)
1307                 return NOPAGE_OOM;
1308         return NULL;
1309
1310 page_not_uptodate:
1311         if (!did_readaround) {
1312                 majmin = VM_FAULT_MAJOR;
1313                 inc_page_state(pgmajfault);
1314         }
1315         lock_page(page);
1316
1317         /* Did it get unhashed while we waited for it? */
1318         if (!page->mapping) {
1319                 unlock_page(page);
1320                 page_cache_release(page);
1321                 goto retry_all;
1322         }
1323
1324         /* Did somebody else get it up-to-date? */
1325         if (PageUptodate(page)) {
1326                 unlock_page(page);
1327                 goto success;
1328         }
1329
1330         if (!mapping->a_ops->readpage(file, page)) {
1331                 wait_on_page_locked(page);
1332                 if (PageUptodate(page))
1333                         goto success;
1334         }
1335
1336         /*
1337          * Umm, take care of errors if the page isn't up-to-date.
1338          * Try to re-read it _once_. We do this synchronously,
1339          * because there really aren't any performance issues here
1340          * and we need to check for errors.
1341          */
1342         lock_page(page);
1343
1344         /* Somebody truncated the page on us? */
1345         if (!page->mapping) {
1346                 unlock_page(page);
1347                 page_cache_release(page);
1348                 goto retry_all;
1349         }
1350
1351         /* Somebody else successfully read it in? */
1352         if (PageUptodate(page)) {
1353                 unlock_page(page);
1354                 goto success;
1355         }
1356         ClearPageError(page);
1357         if (!mapping->a_ops->readpage(file, page)) {
1358                 wait_on_page_locked(page);
1359                 if (PageUptodate(page))
1360                         goto success;
1361         }
1362
1363         /*
1364          * Things didn't work out. Return zero to tell the
1365          * mm layer so, possibly freeing the page cache page first.
1366          */
1367         page_cache_release(page);
1368         return NULL;
1369 }
1370
1371 EXPORT_SYMBOL(filemap_nopage);
1372
1373 static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1374                                         int nonblock)
1375 {
1376         struct address_space *mapping = file->f_mapping;
1377         struct page *page;
1378         int error;
1379
1380         /*
1381          * Do we have something in the page cache already?
1382          */
1383 retry_find:
1384         page = find_get_page(mapping, pgoff);
1385         if (!page) {
1386                 if (nonblock)
1387                         return NULL;
1388                 goto no_cached_page;
1389         }
1390
1391         /*
1392          * Ok, found a page in the page cache, now we need to check
1393          * that it's up-to-date.
1394          */
1395         if (!PageUptodate(page)) {
1396                 if (nonblock) {
1397                         page_cache_release(page);
1398                         return NULL;
1399                 }
1400                 goto page_not_uptodate;
1401         }
1402
1403 success:
1404         /*
1405          * Found the page and have a reference on it.
1406          */
1407         mark_page_accessed(page);
1408         return page;
1409
1410 no_cached_page:
1411         error = page_cache_read(file, pgoff);
1412
1413         /*
1414          * The page we want has now been added to the page cache.
1415          * In the unlikely event that someone removed it in the
1416          * meantime, we'll just come back here and read it again.
1417          */
1418         if (error >= 0)
1419                 goto retry_find;
1420
1421         /*
1422          * An error return from page_cache_read can result if the
1423          * system is low on memory, or a problem occurs while trying
1424          * to schedule I/O.
1425          */
1426         return NULL;
1427
1428 page_not_uptodate:
1429         lock_page(page);
1430
1431         /* Did it get unhashed while we waited for it? */
1432         if (!page->mapping) {
1433                 unlock_page(page);
1434                 goto err;
1435         }
1436
1437         /* Did somebody else get it up-to-date? */
1438         if (PageUptodate(page)) {
1439                 unlock_page(page);
1440                 goto success;
1441         }
1442
1443         if (!mapping->a_ops->readpage(file, page)) {
1444                 wait_on_page_locked(page);
1445                 if (PageUptodate(page))
1446                         goto success;
1447         }
1448
1449         /*
1450          * Umm, take care of errors if the page isn't up-to-date.
1451          * Try to re-read it _once_. We do this synchronously,
1452          * because there really aren't any performance issues here
1453          * and we need to check for errors.
1454          */
1455         lock_page(page);
1456
1457         /* Somebody truncated the page on us? */
1458         if (!page->mapping) {
1459                 unlock_page(page);
1460                 goto err;
1461         }
1462         /* Somebody else successfully read it in? */
1463         if (PageUptodate(page)) {
1464                 unlock_page(page);
1465                 goto success;
1466         }
1467
1468         ClearPageError(page);
1469         if (!mapping->a_ops->readpage(file, page)) {
1470                 wait_on_page_locked(page);
1471                 if (PageUptodate(page))
1472                         goto success;
1473         }
1474
1475         /*
1476          * Things didn't work out. Return zero to tell the
1477          * mm layer so, possibly freeing the page cache page first.
1478          */
1479 err:
1480         page_cache_release(page);
1481
1482         return NULL;
1483 }
1484
1485 int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1486                 unsigned long len, pgprot_t prot, unsigned long pgoff,
1487                 int nonblock)
1488 {
1489         struct file *file = vma->vm_file;
1490         struct address_space *mapping = file->f_mapping;
1491         struct inode *inode = mapping->host;
1492         unsigned long size;
1493         struct mm_struct *mm = vma->vm_mm;
1494         struct page *page;
1495         int err;
1496
1497         if (!nonblock)
1498                 force_page_cache_readahead(mapping, vma->vm_file,
1499                                         pgoff, len >> PAGE_CACHE_SHIFT);
1500
1501 repeat:
1502         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1503         if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1504                 return -EINVAL;
1505
1506         page = filemap_getpage(file, pgoff, nonblock);
1507         if (!page && !nonblock)
1508                 return -ENOMEM;
1509         if (page) {
1510                 err = install_page(mm, vma, addr, page, prot);
1511                 if (err) {
1512                         page_cache_release(page);
1513                         return err;
1514                 }
1515         } else {
1516                 err = install_file_pte(mm, vma, addr, pgoff, prot);
1517                 if (err)
1518                         return err;
1519         }
1520
1521         len -= PAGE_SIZE;
1522         addr += PAGE_SIZE;
1523         pgoff++;
1524         if (len)
1525                 goto repeat;
1526
1527         return 0;
1528 }
1529
1530 struct vm_operations_struct generic_file_vm_ops = {
1531         .nopage         = filemap_nopage,
1532         .populate       = filemap_populate,
1533 };
1534
1535 /* This is used for a general mmap of a disk file */
1536
1537 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1538 {
1539         struct address_space *mapping = file->f_mapping;
1540
1541         if (!mapping->a_ops->readpage)
1542                 return -ENOEXEC;
1543         file_accessed(file);
1544         vma->vm_ops = &generic_file_vm_ops;
1545         return 0;
1546 }
1547 EXPORT_SYMBOL(filemap_populate);
1548
1549 /*
1550  * This is for filesystems which do not implement ->writepage.
1551  */
1552 int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1553 {
1554         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1555                 return -EINVAL;
1556         return generic_file_mmap(file, vma);
1557 }
1558 #else
1559 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1560 {
1561         return -ENOSYS;
1562 }
1563 int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1564 {
1565         return -ENOSYS;
1566 }
1567 #endif /* CONFIG_MMU */
1568
1569 EXPORT_SYMBOL(generic_file_mmap);
1570 EXPORT_SYMBOL(generic_file_readonly_mmap);
1571
1572 static inline struct page *__read_cache_page(struct address_space *mapping,
1573                                 unsigned long index,
1574                                 int (*filler)(void *,struct page*),
1575                                 void *data)
1576 {
1577         struct page *page, *cached_page = NULL;
1578         int err;
1579 repeat:
1580         page = find_get_page(mapping, index);
1581         if (!page) {
1582                 if (!cached_page) {
1583                         cached_page = page_cache_alloc_cold(mapping);
1584                         if (!cached_page)
1585                                 return ERR_PTR(-ENOMEM);
1586                 }
1587                 err = add_to_page_cache_lru(cached_page, mapping,
1588                                         index, GFP_KERNEL);
1589                 if (err == -EEXIST)
1590                         goto repeat;
1591                 if (err < 0) {
1592                         /* Presumably ENOMEM for radix tree node */
1593                         page_cache_release(cached_page);
1594                         return ERR_PTR(err);
1595                 }
1596                 page = cached_page;
1597                 cached_page = NULL;
1598                 err = filler(data, page);
1599                 if (err < 0) {
1600                         page_cache_release(page);
1601                         page = ERR_PTR(err);
1602                 }
1603         }
1604         if (cached_page)
1605                 page_cache_release(cached_page);
1606         return page;
1607 }
1608
1609 /*
1610  * Read into the page cache. If a page already exists,
1611  * and PageUptodate() is not set, try to fill the page.
1612  */
1613 struct page *read_cache_page(struct address_space *mapping,
1614                                 unsigned long index,
1615                                 int (*filler)(void *,struct page*),
1616                                 void *data)
1617 {
1618         struct page *page;
1619         int err;
1620
1621 retry:
1622         page = __read_cache_page(mapping, index, filler, data);
1623         if (IS_ERR(page))
1624                 goto out;
1625         mark_page_accessed(page);
1626         if (PageUptodate(page))
1627                 goto out;
1628
1629         lock_page(page);
1630         if (!page->mapping) {
1631                 unlock_page(page);
1632                 page_cache_release(page);
1633                 goto retry;
1634         }
1635         if (PageUptodate(page)) {
1636                 unlock_page(page);
1637                 goto out;
1638         }
1639         err = filler(data, page);
1640         if (err < 0) {
1641                 page_cache_release(page);
1642                 page = ERR_PTR(err);
1643         }
1644  out:
1645         return page;
1646 }
1647
1648 EXPORT_SYMBOL(read_cache_page);
1649
1650 /*
1651  * If the page was newly created, increment its refcount and add it to the
1652  * caller's lru-buffering pagevec.  This function is specifically for
1653  * generic_file_write().
1654  */
1655 static inline struct page *
1656 __grab_cache_page(struct address_space *mapping, unsigned long index,
1657                         struct page **cached_page, struct pagevec *lru_pvec)
1658 {
1659         int err;
1660         struct page *page;
1661 repeat:
1662         page = find_lock_page(mapping, index);
1663         if (!page) {
1664                 if (!*cached_page) {
1665                         *cached_page = page_cache_alloc(mapping);
1666                         if (!*cached_page)
1667                                 return NULL;
1668                 }
1669                 err = add_to_page_cache(*cached_page, mapping,
1670                                         index, GFP_KERNEL);
1671                 if (err == -EEXIST)
1672                         goto repeat;
1673                 if (err == 0) {
1674                         page = *cached_page;
1675                         page_cache_get(page);
1676                         if (!pagevec_add(lru_pvec, page))
1677                                 __pagevec_lru_add(lru_pvec);
1678                         *cached_page = NULL;
1679                 }
1680         }
1681         return page;
1682 }
1683
1684 /*
1685  * The logic we want is
1686  *
1687  *      if suid or (sgid and xgrp)
1688  *              remove privs
1689  */
1690 int remove_suid(struct dentry *dentry)
1691 {
1692         mode_t mode = dentry->d_inode->i_mode;
1693         int kill = 0;
1694         int result = 0;
1695
1696         /* suid always must be killed */
1697         if (unlikely(mode & S_ISUID))
1698                 kill = ATTR_KILL_SUID;
1699
1700         /*
1701          * sgid without any exec bits is just a mandatory locking mark; leave
1702          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1703          */
1704         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1705                 kill |= ATTR_KILL_SGID;
1706
1707         if (unlikely(kill && !capable(CAP_FSETID))) {
1708                 struct iattr newattrs;
1709
1710                 newattrs.ia_valid = ATTR_FORCE | kill;
1711                 result = notify_change(dentry, &newattrs);
1712         }
1713         return result;
1714 }
1715 EXPORT_SYMBOL(remove_suid);
1716
1717 /*
1718  * Copy as much as we can into the page and return the number of bytes which
1719  * were sucessfully copied.  If a fault is encountered then clear the page
1720  * out to (offset+bytes) and return the number of bytes which were copied.
1721  */
1722 static inline size_t
1723 filemap_copy_from_user(struct page *page, unsigned long offset,
1724                         const char __user *buf, unsigned bytes)
1725 {
1726         char *kaddr;
1727         int left;
1728
1729         kaddr = kmap_atomic(page, KM_USER0);
1730         left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
1731         kunmap_atomic(kaddr, KM_USER0);
1732
1733         if (left != 0) {
1734                 /* Do it the slow way */
1735                 kaddr = kmap(page);
1736                 left = __copy_from_user(kaddr + offset, buf, bytes);
1737                 kunmap(page);
1738         }
1739         return bytes - left;
1740 }
1741
1742 static size_t
1743 __filemap_copy_from_user_iovec(char *vaddr, 
1744                         const struct iovec *iov, size_t base, size_t bytes)
1745 {
1746         size_t copied = 0, left = 0;
1747
1748         while (bytes) {
1749                 char __user *buf = iov->iov_base + base;
1750                 int copy = min(bytes, iov->iov_len - base);
1751
1752                 base = 0;
1753                 left = __copy_from_user_inatomic(vaddr, buf, copy);
1754                 copied += copy;
1755                 bytes -= copy;
1756                 vaddr += copy;
1757                 iov++;
1758
1759                 if (unlikely(left)) {
1760                         /* zero the rest of the target like __copy_from_user */
1761                         if (bytes)
1762                                 memset(vaddr, 0, bytes);
1763                         break;
1764                 }
1765         }
1766         return copied - left;
1767 }
1768
1769 /*
1770  * This has the same sideeffects and return value as filemap_copy_from_user().
1771  * The difference is that on a fault we need to memset the remainder of the
1772  * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
1773  * single-segment behaviour.
1774  */
1775 static inline size_t
1776 filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
1777                         const struct iovec *iov, size_t base, size_t bytes)
1778 {
1779         char *kaddr;
1780         size_t copied;
1781
1782         kaddr = kmap_atomic(page, KM_USER0);
1783         copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1784                                                 base, bytes);
1785         kunmap_atomic(kaddr, KM_USER0);
1786         if (copied != bytes) {
1787                 kaddr = kmap(page);
1788                 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1789                                                         base, bytes);
1790                 kunmap(page);
1791         }
1792         return copied;
1793 }
1794
1795 static inline void
1796 filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
1797 {
1798         const struct iovec *iov = *iovp;
1799         size_t base = *basep;
1800
1801         while (bytes) {
1802                 int copy = min(bytes, iov->iov_len - base);
1803
1804                 bytes -= copy;
1805                 base += copy;
1806                 if (iov->iov_len == base) {
1807                         iov++;
1808                         base = 0;
1809                 }
1810         }
1811         *iovp = iov;
1812         *basep = base;
1813 }
1814
1815 /*
1816  * Performs necessary checks before doing a write
1817  *
1818  * Can adjust writing position aor amount of bytes to write.
1819  * Returns appropriate error code that caller should return or
1820  * zero in case that write should be allowed.
1821  */
1822 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1823 {
1824         struct inode *inode = file->f_mapping->host;
1825         unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1826
1827         if (unlikely(*pos < 0))
1828                 return -EINVAL;
1829
1830         if (unlikely(file->f_error)) {
1831                 int err = file->f_error;
1832                 file->f_error = 0;
1833                 return err;
1834         }
1835
1836         if (!isblk) {
1837                 /* FIXME: this is for backwards compatibility with 2.4 */
1838                 if (file->f_flags & O_APPEND)
1839                         *pos = i_size_read(inode);
1840
1841                 if (limit != RLIM_INFINITY) {
1842                         if (*pos >= limit) {
1843                                 send_sig(SIGXFSZ, current, 0);
1844                                 return -EFBIG;
1845                         }
1846                         if (*count > limit - (typeof(limit))*pos) {
1847                                 *count = limit - (typeof(limit))*pos;
1848                         }
1849                 }
1850         }
1851
1852         /*
1853          * LFS rule
1854          */
1855         if (unlikely(*pos + *count > MAX_NON_LFS &&
1856                                 !(file->f_flags & O_LARGEFILE))) {
1857                 if (*pos >= MAX_NON_LFS) {
1858                         send_sig(SIGXFSZ, current, 0);
1859                         return -EFBIG;
1860                 }
1861                 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1862                         *count = MAX_NON_LFS - (unsigned long)*pos;
1863                 }
1864         }
1865
1866         /*
1867          * Are we about to exceed the fs block limit ?
1868          *
1869          * If we have written data it becomes a short write.  If we have
1870          * exceeded without writing data we send a signal and return EFBIG.
1871          * Linus frestrict idea will clean these up nicely..
1872          */
1873         if (likely(!isblk)) {
1874                 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1875                         if (*count || *pos > inode->i_sb->s_maxbytes) {
1876                                 send_sig(SIGXFSZ, current, 0);
1877                                 return -EFBIG;
1878                         }
1879                         /* zero-length writes at ->s_maxbytes are OK */
1880                 }
1881
1882                 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1883                         *count = inode->i_sb->s_maxbytes - *pos;
1884         } else {
1885                 loff_t isize;
1886                 if (bdev_read_only(I_BDEV(inode)))
1887                         return -EPERM;
1888                 isize = i_size_read(inode);
1889                 if (*pos >= isize) {
1890                         if (*count || *pos > isize)
1891                                 return -ENOSPC;
1892                 }
1893
1894                 if (*pos + *count > isize)
1895                         *count = isize - *pos;
1896         }
1897         return 0;
1898 }
1899 EXPORT_SYMBOL(generic_write_checks);
1900
1901 ssize_t
1902 generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1903                 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1904                 size_t count, size_t ocount)
1905 {
1906         struct file     *file = iocb->ki_filp;
1907         struct address_space *mapping = file->f_mapping;
1908         struct inode    *inode = mapping->host;
1909         ssize_t         written;
1910
1911         if (count != ocount)
1912                 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1913
1914         written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1915         if (written > 0) {
1916                 loff_t end = pos + written;
1917                 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1918                         i_size_write(inode,  end);
1919                         mark_inode_dirty(inode);
1920                 }
1921                 *ppos = end;
1922         }
1923
1924         /*
1925          * Sync the fs metadata but not the minor inode changes and
1926          * of course not the data as we did direct DMA for the IO.
1927          * i_sem is held, which protects generic_osync_inode() from
1928          * livelocking.
1929          */
1930         if (written >= 0 && file->f_flags & O_SYNC)
1931                 generic_osync_inode(inode, mapping, OSYNC_METADATA);
1932         if (written == count && !is_sync_kiocb(iocb))
1933                 written = -EIOCBQUEUED;
1934         return written;
1935 }
1936 EXPORT_SYMBOL(generic_file_direct_write);
1937
1938 ssize_t
1939 generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1940                 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1941                 size_t count, ssize_t written)
1942 {
1943         struct file *file = iocb->ki_filp;
1944         struct address_space * mapping = file->f_mapping;
1945         struct address_space_operations *a_ops = mapping->a_ops;
1946         struct inode    *inode = mapping->host;
1947         long            status = 0;
1948         struct page     *page;
1949         struct page     *cached_page = NULL;
1950         size_t          bytes;
1951         struct pagevec  lru_pvec;
1952         const struct iovec *cur_iov = iov; /* current iovec */
1953         size_t          iov_base = 0;      /* offset in the current iovec */
1954         char __user     *buf;
1955
1956         pagevec_init(&lru_pvec, 0);
1957
1958         /*
1959          * handle partial DIO write.  Adjust cur_iov if needed.
1960          */
1961         if (likely(nr_segs == 1))
1962                 buf = iov->iov_base + written;
1963         else {
1964                 filemap_set_next_iovec(&cur_iov, &iov_base, written);
1965                 buf = cur_iov->iov_base + iov_base;
1966         }
1967
1968         do {
1969                 unsigned long index;
1970                 unsigned long offset;
1971                 size_t copied;
1972
1973                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1974                 index = pos >> PAGE_CACHE_SHIFT;
1975                 bytes = PAGE_CACHE_SIZE - offset;
1976                 if (bytes > count)
1977                         bytes = count;
1978
1979                 /*
1980                  * Bring in the user page that we will copy from _first_.
1981                  * Otherwise there's a nasty deadlock on copying from the
1982                  * same page as we're writing to, without it being marked
1983                  * up-to-date.
1984                  */
1985                 fault_in_pages_readable(buf, bytes);
1986
1987                 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1988                 if (!page) {
1989                         status = -ENOMEM;
1990                         break;
1991                 }
1992
1993                 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1994                 if (unlikely(status)) {
1995                         loff_t isize = i_size_read(inode);
1996                         /*
1997                          * prepare_write() may have instantiated a few blocks
1998                          * outside i_size.  Trim these off again.
1999                          */
2000                         unlock_page(page);
2001                         page_cache_release(page);
2002                         if (pos + bytes > isize)
2003                                 vmtruncate(inode, isize);
2004                         break;
2005                 }
2006                 if (likely(nr_segs == 1))
2007                         copied = filemap_copy_from_user(page, offset,
2008                                                         buf, bytes);
2009                 else
2010                         copied = filemap_copy_from_user_iovec(page, offset,
2011                                                 cur_iov, iov_base, bytes);
2012                 flush_dcache_page(page);
2013                 status = a_ops->commit_write(file, page, offset, offset+bytes);
2014                 if (likely(copied > 0)) {
2015                         if (!status)
2016                                 status = copied;
2017
2018                         if (status >= 0) {
2019                                 written += status;
2020                                 count -= status;
2021                                 pos += status;
2022                                 buf += status;
2023                                 if (unlikely(nr_segs > 1)) {
2024                                         filemap_set_next_iovec(&cur_iov,
2025                                                         &iov_base, status);
2026                                         buf = cur_iov->iov_base + iov_base;
2027                                 }
2028                         }
2029                 }
2030                 if (unlikely(copied != bytes))
2031                         if (status >= 0)
2032                                 status = -EFAULT;
2033                 unlock_page(page);
2034                 mark_page_accessed(page);
2035                 page_cache_release(page);
2036                 if (status < 0)
2037                         break;
2038                 balance_dirty_pages_ratelimited(mapping);
2039                 cond_resched();
2040         } while (count);
2041         *ppos = pos;
2042
2043         if (cached_page)
2044                 page_cache_release(cached_page);
2045
2046         /*
2047          * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2048          */
2049         if (likely(status >= 0)) {
2050                 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2051                         if (!a_ops->writepage || !is_sync_kiocb(iocb))
2052                                 status = generic_osync_inode(inode, mapping,
2053                                                 OSYNC_METADATA|OSYNC_DATA);
2054                 }
2055         }
2056         
2057         /*
2058          * If we get here for O_DIRECT writes then we must have fallen through
2059          * to buffered writes (block instantiation inside i_size).  So we sync
2060          * the file data here, to try to honour O_DIRECT expectations.
2061          */
2062         if (unlikely(file->f_flags & O_DIRECT) && written)
2063                 status = filemap_write_and_wait(mapping);
2064
2065         pagevec_lru_add(&lru_pvec);
2066         return written ? written : status;
2067 }
2068 EXPORT_SYMBOL(generic_file_buffered_write);
2069
2070 ssize_t
2071 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2072                                 unsigned long nr_segs, loff_t *ppos)
2073 {
2074         struct file *file = iocb->ki_filp;
2075         struct address_space * mapping = file->f_mapping;
2076         size_t ocount;          /* original count */
2077         size_t count;           /* after file limit checks */
2078         struct inode    *inode = mapping->host;
2079         unsigned long   seg;
2080         loff_t          pos;
2081         ssize_t         written;
2082         ssize_t         err;
2083
2084         ocount = 0;
2085         for (seg = 0; seg < nr_segs; seg++) {
2086                 const struct iovec *iv = &iov[seg];
2087
2088                 /*
2089                  * If any segment has a negative length, or the cumulative
2090                  * length ever wraps negative then return -EINVAL.
2091                  */
2092                 ocount += iv->iov_len;
2093                 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2094                         return -EINVAL;
2095                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2096                         continue;
2097                 if (seg == 0)
2098                         return -EFAULT;
2099                 nr_segs = seg;
2100                 ocount -= iv->iov_len;  /* This segment is no good */
2101                 break;
2102         }
2103
2104         count = ocount;
2105         pos = *ppos;
2106
2107         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2108
2109         /* We can write back this queue in page reclaim */
2110         current->backing_dev_info = mapping->backing_dev_info;
2111         written = 0;
2112
2113         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2114         if (err)
2115                 goto out;
2116
2117         if (count == 0)
2118                 goto out;
2119
2120         err = remove_suid(file->f_dentry);
2121         if (err)
2122                 goto out;
2123
2124         inode_update_time(inode, 1);
2125
2126         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2127         if (unlikely(file->f_flags & O_DIRECT)) {
2128                 written = generic_file_direct_write(iocb, iov,
2129                                 &nr_segs, pos, ppos, count, ocount);
2130                 if (written < 0 || written == count)
2131                         goto out;
2132                 /*
2133                  * direct-io write to a hole: fall through to buffered I/O
2134                  * for completing the rest of the request.
2135                  */
2136                 pos += written;
2137                 count -= written;
2138         }
2139
2140         written = generic_file_buffered_write(iocb, iov, nr_segs,
2141                         pos, ppos, count, written);
2142 out:
2143         current->backing_dev_info = NULL;
2144         return written ? written : err;
2145 }
2146 EXPORT_SYMBOL(generic_file_aio_write_nolock);
2147
2148 ssize_t
2149 generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2150                                 unsigned long nr_segs, loff_t *ppos)
2151 {
2152         struct file *file = iocb->ki_filp;
2153         struct address_space *mapping = file->f_mapping;
2154         struct inode *inode = mapping->host;
2155         ssize_t ret;
2156         loff_t pos = *ppos;
2157
2158         ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2159
2160         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2161                 int err;
2162
2163                 err = sync_page_range_nolock(inode, mapping, pos, ret);
2164                 if (err < 0)
2165                         ret = err;
2166         }
2167         return ret;
2168 }
2169
2170 ssize_t
2171 __generic_file_write_nolock(struct file *file, const struct iovec *iov,
2172                                 unsigned long nr_segs, loff_t *ppos)
2173 {
2174         struct kiocb kiocb;
2175         ssize_t ret;
2176
2177         init_sync_kiocb(&kiocb, file);
2178         ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2179         if (ret == -EIOCBQUEUED)
2180                 ret = wait_on_sync_kiocb(&kiocb);
2181         return ret;
2182 }
2183
2184 ssize_t
2185 generic_file_write_nolock(struct file *file, const struct iovec *iov,
2186                                 unsigned long nr_segs, loff_t *ppos)
2187 {
2188         struct kiocb kiocb;
2189         ssize_t ret;
2190
2191         init_sync_kiocb(&kiocb, file);
2192         ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2193         if (-EIOCBQUEUED == ret)
2194                 ret = wait_on_sync_kiocb(&kiocb);
2195         return ret;
2196 }
2197 EXPORT_SYMBOL(generic_file_write_nolock);
2198
2199 ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2200                                size_t count, loff_t pos)
2201 {
2202         struct file *file = iocb->ki_filp;
2203         struct address_space *mapping = file->f_mapping;
2204         struct inode *inode = mapping->host;
2205         ssize_t ret;
2206         struct iovec local_iov = { .iov_base = (void __user *)buf,
2207                                         .iov_len = count };
2208
2209         BUG_ON(iocb->ki_pos != pos);
2210
2211         down(&inode->i_sem);
2212         ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2213                                                 &iocb->ki_pos);
2214         up(&inode->i_sem);
2215
2216         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2217                 ssize_t err;
2218
2219                 err = sync_page_range(inode, mapping, pos, ret);
2220                 if (err < 0)
2221                         ret = err;
2222         }
2223         return ret;
2224 }
2225 EXPORT_SYMBOL(generic_file_aio_write);
2226
2227 ssize_t generic_file_write(struct file *file, const char __user *buf,
2228                            size_t count, loff_t *ppos)
2229 {
2230         struct address_space *mapping = file->f_mapping;
2231         struct inode *inode = mapping->host;
2232         ssize_t ret;
2233         struct iovec local_iov = { .iov_base = (void __user *)buf,
2234                                         .iov_len = count };
2235
2236         down(&inode->i_sem);
2237         ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2238         up(&inode->i_sem);
2239
2240         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2241                 ssize_t err;
2242
2243                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2244                 if (err < 0)
2245                         ret = err;
2246         }
2247         return ret;
2248 }
2249 EXPORT_SYMBOL(generic_file_write);
2250
2251 ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2252                         unsigned long nr_segs, loff_t *ppos)
2253 {
2254         struct kiocb kiocb;
2255         ssize_t ret;
2256
2257         init_sync_kiocb(&kiocb, filp);
2258         ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2259         if (-EIOCBQUEUED == ret)
2260                 ret = wait_on_sync_kiocb(&kiocb);
2261         return ret;
2262 }
2263 EXPORT_SYMBOL(generic_file_readv);
2264
2265 ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2266                         unsigned long nr_segs, loff_t *ppos)
2267 {
2268         struct address_space *mapping = file->f_mapping;
2269         struct inode *inode = mapping->host;
2270         ssize_t ret;
2271
2272         down(&inode->i_sem);
2273         ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2274         up(&inode->i_sem);
2275
2276         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2277                 int err;
2278
2279                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2280                 if (err < 0)
2281                         ret = err;
2282         }
2283         return ret;
2284 }
2285 EXPORT_SYMBOL(generic_file_writev);
2286
2287 /*
2288  * Called under i_sem for writes to S_ISREG files.   Returns -EIO if something
2289  * went wrong during pagecache shootdown.
2290  */
2291 ssize_t
2292 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2293         loff_t offset, unsigned long nr_segs)
2294 {
2295         struct file *file = iocb->ki_filp;
2296         struct address_space *mapping = file->f_mapping;
2297         ssize_t retval;
2298         size_t write_len = 0;
2299
2300         /*
2301          * If it's a write, unmap all mmappings of the file up-front.  This
2302          * will cause any pte dirty bits to be propagated into the pageframes
2303          * for the subsequent filemap_write_and_wait().
2304          */
2305         if (rw == WRITE) {
2306                 write_len = iov_length(iov, nr_segs);
2307                 if (mapping_mapped(mapping))
2308                         unmap_mapping_range(mapping, offset, write_len, 0);
2309         }
2310
2311         retval = filemap_write_and_wait(mapping);
2312         if (retval == 0) {
2313                 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2314                                                 offset, nr_segs);
2315                 if (rw == WRITE && mapping->nrpages) {
2316                         pgoff_t end = (offset + write_len - 1)
2317                                                 >> PAGE_CACHE_SHIFT;
2318                         int err = invalidate_inode_pages2_range(mapping,
2319                                         offset >> PAGE_CACHE_SHIFT, end);
2320                         if (err)
2321                                 retval = err;
2322                 }
2323         }
2324         return retval;
2325 }
2326 EXPORT_SYMBOL_GPL(generic_file_direct_IO);