[PATCH] Exterminate PAGE_BUG
[linux-3.10.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  * 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  */
112 void __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
122 void remove_from_page_cache(struct page *page)
123 {
124         struct address_space *mapping = page->mapping;
125
126         BUG_ON(!PageLocked(page));
127
128         write_lock_irq(&mapping->tree_lock);
129         __remove_from_page_cache(page);
130         write_unlock_irq(&mapping->tree_lock);
131 }
132
133 static int sync_page(void *word)
134 {
135         struct address_space *mapping;
136         struct page *page;
137
138         page = container_of((page_flags_t *)word, struct page, flags);
139
140         /*
141          * page_mapping() is being called without PG_locked held.
142          * Some knowledge of the state and use of the page is used to
143          * reduce the requirements down to a memory barrier.
144          * The danger here is of a stale page_mapping() return value
145          * indicating a struct address_space different from the one it's
146          * associated with when it is associated with one.
147          * After smp_mb(), it's either the correct page_mapping() for
148          * the page, or an old page_mapping() and the page's own
149          * page_mapping() has gone NULL.
150          * The ->sync_page() address_space operation must tolerate
151          * page_mapping() going NULL. By an amazing coincidence,
152          * this comes about because none of the users of the page
153          * in the ->sync_page() methods make essential use of the
154          * page_mapping(), merely passing the page down to the backing
155          * device's unplug functions when it's non-NULL, which in turn
156          * ignore it for all cases but swap, where only page->private is
157          * of interest. When page_mapping() does go NULL, the entire
158          * call stack gracefully ignores the page and returns.
159          * -- wli
160          */
161         smp_mb();
162         mapping = page_mapping(page);
163         if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
164                 mapping->a_ops->sync_page(page);
165         io_schedule();
166         return 0;
167 }
168
169 /**
170  * filemap_fdatawrite_range - start writeback against all of a mapping's
171  * dirty pages that lie within the byte offsets <start, end>
172  * @mapping: address space structure to write
173  * @start: offset in bytes where the range starts
174  * @end : offset in bytes where the range ends
175  *
176  * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
177  * opposed to a regular memory * cleansing writeback.  The difference between
178  * these two operations is that if a dirty page/buffer is encountered, it must
179  * be waited upon, and not just skipped over.
180  */
181 static int __filemap_fdatawrite_range(struct address_space *mapping,
182         loff_t start, loff_t end, int sync_mode)
183 {
184         int ret;
185         struct writeback_control wbc = {
186                 .sync_mode = sync_mode,
187                 .nr_to_write = mapping->nrpages * 2,
188                 .start = start,
189                 .end = end,
190         };
191
192         if (!mapping_cap_writeback_dirty(mapping))
193                 return 0;
194
195         ret = do_writepages(mapping, &wbc);
196         return ret;
197 }
198
199 static inline int __filemap_fdatawrite(struct address_space *mapping,
200         int sync_mode)
201 {
202         return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
203 }
204
205 int filemap_fdatawrite(struct address_space *mapping)
206 {
207         return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
208 }
209 EXPORT_SYMBOL(filemap_fdatawrite);
210
211 static int filemap_fdatawrite_range(struct address_space *mapping,
212         loff_t start, loff_t end)
213 {
214         return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
215 }
216
217 /*
218  * This is a mostly non-blocking flush.  Not suitable for data-integrity
219  * purposes - I/O may not be started against all dirty pages.
220  */
221 int filemap_flush(struct address_space *mapping)
222 {
223         return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
224 }
225 EXPORT_SYMBOL(filemap_flush);
226
227 /*
228  * Wait for writeback to complete against pages indexed by start->end
229  * inclusive
230  */
231 static int wait_on_page_writeback_range(struct address_space *mapping,
232                                 pgoff_t start, pgoff_t end)
233 {
234         struct pagevec pvec;
235         int nr_pages;
236         int ret = 0;
237         pgoff_t index;
238
239         if (end < start)
240                 return 0;
241
242         pagevec_init(&pvec, 0);
243         index = start;
244         while ((index <= end) &&
245                         (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
246                         PAGECACHE_TAG_WRITEBACK,
247                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
248                 unsigned i;
249
250                 for (i = 0; i < nr_pages; i++) {
251                         struct page *page = pvec.pages[i];
252
253                         /* until radix tree lookup accepts end_index */
254                         if (page->index > end)
255                                 continue;
256
257                         wait_on_page_writeback(page);
258                         if (PageError(page))
259                                 ret = -EIO;
260                 }
261                 pagevec_release(&pvec);
262                 cond_resched();
263         }
264
265         /* Check for outstanding write errors */
266         if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
267                 ret = -ENOSPC;
268         if (test_and_clear_bit(AS_EIO, &mapping->flags))
269                 ret = -EIO;
270
271         return ret;
272 }
273
274 /*
275  * Write and wait upon all the pages in the passed range.  This is a "data
276  * integrity" operation.  It waits upon in-flight writeout before starting and
277  * waiting upon new writeout.  If there was an IO error, return it.
278  *
279  * We need to re-take i_sem during the generic_osync_inode list walk because
280  * it is otherwise livelockable.
281  */
282 int sync_page_range(struct inode *inode, struct address_space *mapping,
283                         loff_t pos, size_t count)
284 {
285         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
286         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
287         int ret;
288
289         if (!mapping_cap_writeback_dirty(mapping) || !count)
290                 return 0;
291         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
292         if (ret == 0) {
293                 down(&inode->i_sem);
294                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
295                 up(&inode->i_sem);
296         }
297         if (ret == 0)
298                 ret = wait_on_page_writeback_range(mapping, start, end);
299         return ret;
300 }
301 EXPORT_SYMBOL(sync_page_range);
302
303 /*
304  * Note: Holding i_sem across sync_page_range_nolock is not a good idea
305  * as it forces O_SYNC writers to different parts of the same file
306  * to be serialised right until io completion.
307  */
308 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
309                         loff_t pos, size_t count)
310 {
311         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
312         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
313         int ret;
314
315         if (!mapping_cap_writeback_dirty(mapping) || !count)
316                 return 0;
317         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
318         if (ret == 0)
319                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
320         if (ret == 0)
321                 ret = wait_on_page_writeback_range(mapping, start, end);
322         return ret;
323 }
324 EXPORT_SYMBOL(sync_page_range_nolock);
325
326 /**
327  * filemap_fdatawait - walk the list of under-writeback pages of the given
328  *     address space and wait for all of them.
329  *
330  * @mapping: address space structure to wait for
331  */
332 int filemap_fdatawait(struct address_space *mapping)
333 {
334         loff_t i_size = i_size_read(mapping->host);
335
336         if (i_size == 0)
337                 return 0;
338
339         return wait_on_page_writeback_range(mapping, 0,
340                                 (i_size - 1) >> PAGE_CACHE_SHIFT);
341 }
342 EXPORT_SYMBOL(filemap_fdatawait);
343
344 int filemap_write_and_wait(struct address_space *mapping)
345 {
346         int retval = 0;
347
348         if (mapping->nrpages) {
349                 retval = filemap_fdatawrite(mapping);
350                 if (retval == 0)
351                         retval = filemap_fdatawait(mapping);
352         }
353         return retval;
354 }
355
356 int filemap_write_and_wait_range(struct address_space *mapping,
357                                  loff_t lstart, loff_t lend)
358 {
359         int retval = 0;
360
361         if (mapping->nrpages) {
362                 retval = __filemap_fdatawrite_range(mapping, lstart, lend,
363                                                     WB_SYNC_ALL);
364                 if (retval == 0)
365                         retval = wait_on_page_writeback_range(mapping,
366                                                     lstart >> PAGE_CACHE_SHIFT,
367                                                     lend >> PAGE_CACHE_SHIFT);
368         }
369         return retval;
370 }
371
372 /*
373  * This function is used to add newly allocated pagecache pages:
374  * the page is new, so we can just run SetPageLocked() against it.
375  * The other page state flags were set by rmqueue().
376  *
377  * This function does not add the page to the LRU.  The caller must do that.
378  */
379 int add_to_page_cache(struct page *page, struct address_space *mapping,
380                 pgoff_t offset, int gfp_mask)
381 {
382         int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
383
384         if (error == 0) {
385                 write_lock_irq(&mapping->tree_lock);
386                 error = radix_tree_insert(&mapping->page_tree, offset, page);
387                 if (!error) {
388                         page_cache_get(page);
389                         SetPageLocked(page);
390                         page->mapping = mapping;
391                         page->index = offset;
392                         mapping->nrpages++;
393                         pagecache_acct(1);
394                 }
395                 write_unlock_irq(&mapping->tree_lock);
396                 radix_tree_preload_end();
397         }
398         return error;
399 }
400
401 EXPORT_SYMBOL(add_to_page_cache);
402
403 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
404                                 pgoff_t offset, int gfp_mask)
405 {
406         int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
407         if (ret == 0)
408                 lru_cache_add(page);
409         return ret;
410 }
411
412 /*
413  * In order to wait for pages to become available there must be
414  * waitqueues associated with pages. By using a hash table of
415  * waitqueues where the bucket discipline is to maintain all
416  * waiters on the same queue and wake all when any of the pages
417  * become available, and for the woken contexts to check to be
418  * sure the appropriate page became available, this saves space
419  * at a cost of "thundering herd" phenomena during rare hash
420  * collisions.
421  */
422 static wait_queue_head_t *page_waitqueue(struct page *page)
423 {
424         const struct zone *zone = page_zone(page);
425
426         return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
427 }
428
429 static inline void wake_up_page(struct page *page, int bit)
430 {
431         __wake_up_bit(page_waitqueue(page), &page->flags, bit);
432 }
433
434 void fastcall wait_on_page_bit(struct page *page, int bit_nr)
435 {
436         DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
437
438         if (test_bit(bit_nr, &page->flags))
439                 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
440                                                         TASK_UNINTERRUPTIBLE);
441 }
442 EXPORT_SYMBOL(wait_on_page_bit);
443
444 /**
445  * unlock_page() - unlock a locked page
446  *
447  * @page: the page
448  *
449  * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
450  * Also wakes sleepers in wait_on_page_writeback() because the wakeup
451  * mechananism between PageLocked pages and PageWriteback pages is shared.
452  * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
453  *
454  * The first mb is necessary to safely close the critical section opened by the
455  * TestSetPageLocked(), the second mb is necessary to enforce ordering between
456  * the clear_bit and the read of the waitqueue (to avoid SMP races with a
457  * parallel wait_on_page_locked()).
458  */
459 void fastcall unlock_page(struct page *page)
460 {
461         smp_mb__before_clear_bit();
462         if (!TestClearPageLocked(page))
463                 BUG();
464         smp_mb__after_clear_bit(); 
465         wake_up_page(page, PG_locked);
466 }
467 EXPORT_SYMBOL(unlock_page);
468
469 /*
470  * End writeback against a page.
471  */
472 void end_page_writeback(struct page *page)
473 {
474         if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
475                 if (!test_clear_page_writeback(page))
476                         BUG();
477         }
478         smp_mb__after_clear_bit();
479         wake_up_page(page, PG_writeback);
480 }
481 EXPORT_SYMBOL(end_page_writeback);
482
483 /*
484  * Get a lock on the page, assuming we need to sleep to get it.
485  *
486  * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary.  If some
487  * random driver's requestfn sets TASK_RUNNING, we could busywait.  However
488  * chances are that on the second loop, the block layer's plug list is empty,
489  * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
490  */
491 void fastcall __lock_page(struct page *page)
492 {
493         DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
494
495         __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
496                                                         TASK_UNINTERRUPTIBLE);
497 }
498 EXPORT_SYMBOL(__lock_page);
499
500 /*
501  * a rather lightweight function, finding and getting a reference to a
502  * hashed page atomically.
503  */
504 struct page * find_get_page(struct address_space *mapping, unsigned long offset)
505 {
506         struct page *page;
507
508         read_lock_irq(&mapping->tree_lock);
509         page = radix_tree_lookup(&mapping->page_tree, offset);
510         if (page)
511                 page_cache_get(page);
512         read_unlock_irq(&mapping->tree_lock);
513         return page;
514 }
515
516 EXPORT_SYMBOL(find_get_page);
517
518 /*
519  * Same as above, but trylock it instead of incrementing the count.
520  */
521 struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
522 {
523         struct page *page;
524
525         read_lock_irq(&mapping->tree_lock);
526         page = radix_tree_lookup(&mapping->page_tree, offset);
527         if (page && TestSetPageLocked(page))
528                 page = NULL;
529         read_unlock_irq(&mapping->tree_lock);
530         return page;
531 }
532
533 EXPORT_SYMBOL(find_trylock_page);
534
535 /**
536  * find_lock_page - locate, pin and lock a pagecache page
537  *
538  * @mapping - the address_space to search
539  * @offset - the page index
540  *
541  * Locates the desired pagecache page, locks it, increments its reference
542  * count and returns its address.
543  *
544  * Returns zero if the page was not present. find_lock_page() may sleep.
545  */
546 struct page *find_lock_page(struct address_space *mapping,
547                                 unsigned long offset)
548 {
549         struct page *page;
550
551         read_lock_irq(&mapping->tree_lock);
552 repeat:
553         page = radix_tree_lookup(&mapping->page_tree, offset);
554         if (page) {
555                 page_cache_get(page);
556                 if (TestSetPageLocked(page)) {
557                         read_unlock_irq(&mapping->tree_lock);
558                         lock_page(page);
559                         read_lock_irq(&mapping->tree_lock);
560
561                         /* Has the page been truncated while we slept? */
562                         if (page->mapping != mapping || page->index != offset) {
563                                 unlock_page(page);
564                                 page_cache_release(page);
565                                 goto repeat;
566                         }
567                 }
568         }
569         read_unlock_irq(&mapping->tree_lock);
570         return page;
571 }
572
573 EXPORT_SYMBOL(find_lock_page);
574
575 /**
576  * find_or_create_page - locate or add a pagecache page
577  *
578  * @mapping - the page's address_space
579  * @index - the page's index into the mapping
580  * @gfp_mask - page allocation mode
581  *
582  * Locates a page in the pagecache.  If the page is not present, a new page
583  * is allocated using @gfp_mask and is added to the pagecache and to the VM's
584  * LRU list.  The returned page is locked and has its reference count
585  * incremented.
586  *
587  * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
588  * allocation!
589  *
590  * find_or_create_page() returns the desired page's address, or zero on
591  * memory exhaustion.
592  */
593 struct page *find_or_create_page(struct address_space *mapping,
594                 unsigned long index, unsigned int gfp_mask)
595 {
596         struct page *page, *cached_page = NULL;
597         int err;
598 repeat:
599         page = find_lock_page(mapping, index);
600         if (!page) {
601                 if (!cached_page) {
602                         cached_page = alloc_page(gfp_mask);
603                         if (!cached_page)
604                                 return NULL;
605                 }
606                 err = add_to_page_cache_lru(cached_page, mapping,
607                                         index, gfp_mask);
608                 if (!err) {
609                         page = cached_page;
610                         cached_page = NULL;
611                 } else if (err == -EEXIST)
612                         goto repeat;
613         }
614         if (cached_page)
615                 page_cache_release(cached_page);
616         return page;
617 }
618
619 EXPORT_SYMBOL(find_or_create_page);
620
621 /**
622  * find_get_pages - gang pagecache lookup
623  * @mapping:    The address_space to search
624  * @start:      The starting page index
625  * @nr_pages:   The maximum number of pages
626  * @pages:      Where the resulting pages are placed
627  *
628  * find_get_pages() will search for and return a group of up to
629  * @nr_pages pages in the mapping.  The pages are placed at @pages.
630  * find_get_pages() takes a reference against the returned pages.
631  *
632  * The search returns a group of mapping-contiguous pages with ascending
633  * indexes.  There may be holes in the indices due to not-present pages.
634  *
635  * find_get_pages() returns the number of pages which were found.
636  */
637 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
638                             unsigned int nr_pages, struct page **pages)
639 {
640         unsigned int i;
641         unsigned int ret;
642
643         read_lock_irq(&mapping->tree_lock);
644         ret = radix_tree_gang_lookup(&mapping->page_tree,
645                                 (void **)pages, start, nr_pages);
646         for (i = 0; i < ret; i++)
647                 page_cache_get(pages[i]);
648         read_unlock_irq(&mapping->tree_lock);
649         return ret;
650 }
651
652 /*
653  * Like find_get_pages, except we only return pages which are tagged with
654  * `tag'.   We update *index to index the next page for the traversal.
655  */
656 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
657                         int tag, unsigned int nr_pages, struct page **pages)
658 {
659         unsigned int i;
660         unsigned int ret;
661
662         read_lock_irq(&mapping->tree_lock);
663         ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
664                                 (void **)pages, *index, nr_pages, tag);
665         for (i = 0; i < ret; i++)
666                 page_cache_get(pages[i]);
667         if (ret)
668                 *index = pages[ret - 1]->index + 1;
669         read_unlock_irq(&mapping->tree_lock);
670         return ret;
671 }
672
673 /*
674  * Same as grab_cache_page, but do not wait if the page is unavailable.
675  * This is intended for speculative data generators, where the data can
676  * be regenerated if the page couldn't be grabbed.  This routine should
677  * be safe to call while holding the lock for another page.
678  *
679  * Clear __GFP_FS when allocating the page to avoid recursion into the fs
680  * and deadlock against the caller's locked page.
681  */
682 struct page *
683 grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
684 {
685         struct page *page = find_get_page(mapping, index);
686         unsigned int gfp_mask;
687
688         if (page) {
689                 if (!TestSetPageLocked(page))
690                         return page;
691                 page_cache_release(page);
692                 return NULL;
693         }
694         gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
695         page = alloc_pages(gfp_mask, 0);
696         if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
697                 page_cache_release(page);
698                 page = NULL;
699         }
700         return page;
701 }
702
703 EXPORT_SYMBOL(grab_cache_page_nowait);
704
705 /*
706  * This is a generic file read routine, and uses the
707  * mapping->a_ops->readpage() function for the actual low-level
708  * stuff.
709  *
710  * This is really ugly. But the goto's actually try to clarify some
711  * of the logic when it comes to error handling etc.
712  *
713  * Note the struct file* is only passed for the use of readpage.  It may be
714  * NULL.
715  */
716 void do_generic_mapping_read(struct address_space *mapping,
717                              struct file_ra_state *_ra,
718                              struct file *filp,
719                              loff_t *ppos,
720                              read_descriptor_t *desc,
721                              read_actor_t actor)
722 {
723         struct inode *inode = mapping->host;
724         unsigned long index;
725         unsigned long end_index;
726         unsigned long offset;
727         unsigned long last_index;
728         unsigned long next_index;
729         unsigned long prev_index;
730         loff_t isize;
731         struct page *cached_page;
732         int error;
733         struct file_ra_state ra = *_ra;
734
735         cached_page = NULL;
736         index = *ppos >> PAGE_CACHE_SHIFT;
737         next_index = index;
738         prev_index = ra.prev_page;
739         last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
740         offset = *ppos & ~PAGE_CACHE_MASK;
741
742         isize = i_size_read(inode);
743         if (!isize)
744                 goto out;
745
746         end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
747         for (;;) {
748                 struct page *page;
749                 unsigned long nr, ret;
750
751                 /* nr is the maximum number of bytes to copy from this page */
752                 nr = PAGE_CACHE_SIZE;
753                 if (index >= end_index) {
754                         if (index > end_index)
755                                 goto out;
756                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
757                         if (nr <= offset) {
758                                 goto out;
759                         }
760                 }
761                 nr = nr - offset;
762
763                 cond_resched();
764                 if (index == next_index)
765                         next_index = page_cache_readahead(mapping, &ra, filp,
766                                         index, last_index - index);
767
768 find_page:
769                 page = find_get_page(mapping, index);
770                 if (unlikely(page == NULL)) {
771                         handle_ra_miss(mapping, &ra, index);
772                         goto no_cached_page;
773                 }
774                 if (!PageUptodate(page))
775                         goto page_not_up_to_date;
776 page_ok:
777
778                 /* If users can be writing to this page using arbitrary
779                  * virtual addresses, take care about potential aliasing
780                  * before reading the page on the kernel side.
781                  */
782                 if (mapping_writably_mapped(mapping))
783                         flush_dcache_page(page);
784
785                 /*
786                  * When (part of) the same page is read multiple times
787                  * in succession, only mark it as accessed the first time.
788                  */
789                 if (prev_index != index)
790                         mark_page_accessed(page);
791                 prev_index = index;
792
793                 /*
794                  * Ok, we have the page, and it's up-to-date, so
795                  * now we can copy it to user space...
796                  *
797                  * The actor routine returns how many bytes were actually used..
798                  * NOTE! This may not be the same as how much of a user buffer
799                  * we filled up (we may be padding etc), so we can only update
800                  * "pos" here (the actor routine has to update the user buffer
801                  * pointers and the remaining count).
802                  */
803                 ret = actor(desc, page, offset, nr);
804                 offset += ret;
805                 index += offset >> PAGE_CACHE_SHIFT;
806                 offset &= ~PAGE_CACHE_MASK;
807
808                 page_cache_release(page);
809                 if (ret == nr && desc->count)
810                         continue;
811                 goto out;
812
813 page_not_up_to_date:
814                 /* Get exclusive access to the page ... */
815                 lock_page(page);
816
817                 /* Did it get unhashed before we got the lock? */
818                 if (!page->mapping) {
819                         unlock_page(page);
820                         page_cache_release(page);
821                         continue;
822                 }
823
824                 /* Did somebody else fill it already? */
825                 if (PageUptodate(page)) {
826                         unlock_page(page);
827                         goto page_ok;
828                 }
829
830 readpage:
831                 /* Start the actual read. The read will unlock the page. */
832                 error = mapping->a_ops->readpage(filp, page);
833
834                 if (unlikely(error))
835                         goto readpage_error;
836
837                 if (!PageUptodate(page)) {
838                         lock_page(page);
839                         if (!PageUptodate(page)) {
840                                 if (page->mapping == NULL) {
841                                         /*
842                                          * invalidate_inode_pages got it
843                                          */
844                                         unlock_page(page);
845                                         page_cache_release(page);
846                                         goto find_page;
847                                 }
848                                 unlock_page(page);
849                                 error = -EIO;
850                                 goto readpage_error;
851                         }
852                         unlock_page(page);
853                 }
854
855                 /*
856                  * i_size must be checked after we have done ->readpage.
857                  *
858                  * Checking i_size after the readpage allows us to calculate
859                  * the correct value for "nr", which means the zero-filled
860                  * part of the page is not copied back to userspace (unless
861                  * another truncate extends the file - this is desired though).
862                  */
863                 isize = i_size_read(inode);
864                 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
865                 if (unlikely(!isize || index > end_index)) {
866                         page_cache_release(page);
867                         goto out;
868                 }
869
870                 /* nr is the maximum number of bytes to copy from this page */
871                 nr = PAGE_CACHE_SIZE;
872                 if (index == end_index) {
873                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
874                         if (nr <= offset) {
875                                 page_cache_release(page);
876                                 goto out;
877                         }
878                 }
879                 nr = nr - offset;
880                 goto page_ok;
881
882 readpage_error:
883                 /* UHHUH! A synchronous read error occurred. Report it */
884                 desc->error = error;
885                 page_cache_release(page);
886                 goto out;
887
888 no_cached_page:
889                 /*
890                  * Ok, it wasn't cached, so we need to create a new
891                  * page..
892                  */
893                 if (!cached_page) {
894                         cached_page = page_cache_alloc_cold(mapping);
895                         if (!cached_page) {
896                                 desc->error = -ENOMEM;
897                                 goto out;
898                         }
899                 }
900                 error = add_to_page_cache_lru(cached_page, mapping,
901                                                 index, GFP_KERNEL);
902                 if (error) {
903                         if (error == -EEXIST)
904                                 goto find_page;
905                         desc->error = error;
906                         goto out;
907                 }
908                 page = cached_page;
909                 cached_page = NULL;
910                 goto readpage;
911         }
912
913 out:
914         *_ra = ra;
915
916         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
917         if (cached_page)
918                 page_cache_release(cached_page);
919         if (filp)
920                 file_accessed(filp);
921 }
922
923 EXPORT_SYMBOL(do_generic_mapping_read);
924
925 int file_read_actor(read_descriptor_t *desc, struct page *page,
926                         unsigned long offset, unsigned long size)
927 {
928         char *kaddr;
929         unsigned long left, count = desc->count;
930
931         if (size > count)
932                 size = count;
933
934         /*
935          * Faults on the destination of a read are common, so do it before
936          * taking the kmap.
937          */
938         if (!fault_in_pages_writeable(desc->arg.buf, size)) {
939                 kaddr = kmap_atomic(page, KM_USER0);
940                 left = __copy_to_user_inatomic(desc->arg.buf,
941                                                 kaddr + offset, size);
942                 kunmap_atomic(kaddr, KM_USER0);
943                 if (left == 0)
944                         goto success;
945         }
946
947         /* Do it the slow way */
948         kaddr = kmap(page);
949         left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
950         kunmap(page);
951
952         if (left) {
953                 size -= left;
954                 desc->error = -EFAULT;
955         }
956 success:
957         desc->count = count - size;
958         desc->written += size;
959         desc->arg.buf += size;
960         return size;
961 }
962
963 /*
964  * This is the "read()" routine for all filesystems
965  * that can use the page cache directly.
966  */
967 ssize_t
968 __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
969                 unsigned long nr_segs, loff_t *ppos)
970 {
971         struct file *filp = iocb->ki_filp;
972         ssize_t retval;
973         unsigned long seg;
974         size_t count;
975
976         count = 0;
977         for (seg = 0; seg < nr_segs; seg++) {
978                 const struct iovec *iv = &iov[seg];
979
980                 /*
981                  * If any segment has a negative length, or the cumulative
982                  * length ever wraps negative then return -EINVAL.
983                  */
984                 count += iv->iov_len;
985                 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
986                         return -EINVAL;
987                 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
988                         continue;
989                 if (seg == 0)
990                         return -EFAULT;
991                 nr_segs = seg;
992                 count -= iv->iov_len;   /* This segment is no good */
993                 break;
994         }
995
996         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
997         if (filp->f_flags & O_DIRECT) {
998                 loff_t pos = *ppos, size;
999                 struct address_space *mapping;
1000                 struct inode *inode;
1001
1002                 mapping = filp->f_mapping;
1003                 inode = mapping->host;
1004                 retval = 0;
1005                 if (!count)
1006                         goto out; /* skip atime */
1007                 size = i_size_read(inode);
1008                 if (pos < size) {
1009                         retval = generic_file_direct_IO(READ, iocb,
1010                                                 iov, pos, nr_segs);
1011                         if (retval >= 0 && !is_sync_kiocb(iocb))
1012                                 retval = -EIOCBQUEUED;
1013                         if (retval > 0)
1014                                 *ppos = pos + retval;
1015                 }
1016                 file_accessed(filp);
1017                 goto out;
1018         }
1019
1020         retval = 0;
1021         if (count) {
1022                 for (seg = 0; seg < nr_segs; seg++) {
1023                         read_descriptor_t desc;
1024
1025                         desc.written = 0;
1026                         desc.arg.buf = iov[seg].iov_base;
1027                         desc.count = iov[seg].iov_len;
1028                         if (desc.count == 0)
1029                                 continue;
1030                         desc.error = 0;
1031                         do_generic_file_read(filp,ppos,&desc,file_read_actor);
1032                         retval += desc.written;
1033                         if (!retval) {
1034                                 retval = desc.error;
1035                                 break;
1036                         }
1037                 }
1038         }
1039 out:
1040         return retval;
1041 }
1042
1043 EXPORT_SYMBOL(__generic_file_aio_read);
1044
1045 ssize_t
1046 generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1047 {
1048         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1049
1050         BUG_ON(iocb->ki_pos != pos);
1051         return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1052 }
1053
1054 EXPORT_SYMBOL(generic_file_aio_read);
1055
1056 ssize_t
1057 generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1058 {
1059         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1060         struct kiocb kiocb;
1061         ssize_t ret;
1062
1063         init_sync_kiocb(&kiocb, filp);
1064         ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1065         if (-EIOCBQUEUED == ret)
1066                 ret = wait_on_sync_kiocb(&kiocb);
1067         return ret;
1068 }
1069
1070 EXPORT_SYMBOL(generic_file_read);
1071
1072 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1073 {
1074         ssize_t written;
1075         unsigned long count = desc->count;
1076         struct file *file = desc->arg.data;
1077
1078         if (size > count)
1079                 size = count;
1080
1081         written = file->f_op->sendpage(file, page, offset,
1082                                        size, &file->f_pos, size<count);
1083         if (written < 0) {
1084                 desc->error = written;
1085                 written = 0;
1086         }
1087         desc->count = count - written;
1088         desc->written += written;
1089         return written;
1090 }
1091
1092 ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1093                          size_t count, read_actor_t actor, void *target)
1094 {
1095         read_descriptor_t desc;
1096
1097         if (!count)
1098                 return 0;
1099
1100         desc.written = 0;
1101         desc.count = count;
1102         desc.arg.data = target;
1103         desc.error = 0;
1104
1105         do_generic_file_read(in_file, ppos, &desc, actor);
1106         if (desc.written)
1107                 return desc.written;
1108         return desc.error;
1109 }
1110
1111 EXPORT_SYMBOL(generic_file_sendfile);
1112
1113 static ssize_t
1114 do_readahead(struct address_space *mapping, struct file *filp,
1115              unsigned long index, unsigned long nr)
1116 {
1117         if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1118                 return -EINVAL;
1119
1120         force_page_cache_readahead(mapping, filp, index,
1121                                         max_sane_readahead(nr));
1122         return 0;
1123 }
1124
1125 asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1126 {
1127         ssize_t ret;
1128         struct file *file;
1129
1130         ret = -EBADF;
1131         file = fget(fd);
1132         if (file) {
1133                 if (file->f_mode & FMODE_READ) {
1134                         struct address_space *mapping = file->f_mapping;
1135                         unsigned long start = offset >> PAGE_CACHE_SHIFT;
1136                         unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1137                         unsigned long len = end - start + 1;
1138                         ret = do_readahead(mapping, file, start, len);
1139                 }
1140                 fput(file);
1141         }
1142         return ret;
1143 }
1144
1145 #ifdef CONFIG_MMU
1146 /*
1147  * This adds the requested page to the page cache if it isn't already there,
1148  * and schedules an I/O to read in its contents from disk.
1149  */
1150 static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1151 static int fastcall page_cache_read(struct file * file, unsigned long offset)
1152 {
1153         struct address_space *mapping = file->f_mapping;
1154         struct page *page; 
1155         int error;
1156
1157         page = page_cache_alloc_cold(mapping);
1158         if (!page)
1159                 return -ENOMEM;
1160
1161         error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1162         if (!error) {
1163                 error = mapping->a_ops->readpage(file, page);
1164                 page_cache_release(page);
1165                 return error;
1166         }
1167
1168         /*
1169          * We arrive here in the unlikely event that someone 
1170          * raced with us and added our page to the cache first
1171          * or we are out of memory for radix-tree nodes.
1172          */
1173         page_cache_release(page);
1174         return error == -EEXIST ? 0 : error;
1175 }
1176
1177 #define MMAP_LOTSAMISS  (100)
1178
1179 /*
1180  * filemap_nopage() is invoked via the vma operations vector for a
1181  * mapped memory region to read in file data during a page fault.
1182  *
1183  * The goto's are kind of ugly, but this streamlines the normal case of having
1184  * it in the page cache, and handles the special cases reasonably without
1185  * having a lot of duplicated code.
1186  */
1187 struct page *filemap_nopage(struct vm_area_struct *area,
1188                                 unsigned long address, int *type)
1189 {
1190         int error;
1191         struct file *file = area->vm_file;
1192         struct address_space *mapping = file->f_mapping;
1193         struct file_ra_state *ra = &file->f_ra;
1194         struct inode *inode = mapping->host;
1195         struct page *page;
1196         unsigned long size, pgoff;
1197         int did_readaround = 0, majmin = VM_FAULT_MINOR;
1198
1199         pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1200
1201 retry_all:
1202         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1203         if (pgoff >= size)
1204                 goto outside_data_content;
1205
1206         /* If we don't want any read-ahead, don't bother */
1207         if (VM_RandomReadHint(area))
1208                 goto no_cached_page;
1209
1210         /*
1211          * The readahead code wants to be told about each and every page
1212          * so it can build and shrink its windows appropriately
1213          *
1214          * For sequential accesses, we use the generic readahead logic.
1215          */
1216         if (VM_SequentialReadHint(area))
1217                 page_cache_readahead(mapping, ra, file, pgoff, 1);
1218
1219         /*
1220          * Do we have something in the page cache already?
1221          */
1222 retry_find:
1223         page = find_get_page(mapping, pgoff);
1224         if (!page) {
1225                 unsigned long ra_pages;
1226
1227                 if (VM_SequentialReadHint(area)) {
1228                         handle_ra_miss(mapping, ra, pgoff);
1229                         goto no_cached_page;
1230                 }
1231                 ra->mmap_miss++;
1232
1233                 /*
1234                  * Do we miss much more than hit in this file? If so,
1235                  * stop bothering with read-ahead. It will only hurt.
1236                  */
1237                 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1238                         goto no_cached_page;
1239
1240                 /*
1241                  * To keep the pgmajfault counter straight, we need to
1242                  * check did_readaround, as this is an inner loop.
1243                  */
1244                 if (!did_readaround) {
1245                         majmin = VM_FAULT_MAJOR;
1246                         inc_page_state(pgmajfault);
1247                 }
1248                 did_readaround = 1;
1249                 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1250                 if (ra_pages) {
1251                         pgoff_t start = 0;
1252
1253                         if (pgoff > ra_pages / 2)
1254                                 start = pgoff - ra_pages / 2;
1255                         do_page_cache_readahead(mapping, file, start, ra_pages);
1256                 }
1257                 page = find_get_page(mapping, pgoff);
1258                 if (!page)
1259                         goto no_cached_page;
1260         }
1261
1262         if (!did_readaround)
1263                 ra->mmap_hit++;
1264
1265         /*
1266          * Ok, found a page in the page cache, now we need to check
1267          * that it's up-to-date.
1268          */
1269         if (!PageUptodate(page))
1270                 goto page_not_uptodate;
1271
1272 success:
1273         /*
1274          * Found the page and have a reference on it.
1275          */
1276         mark_page_accessed(page);
1277         if (type)
1278                 *type = majmin;
1279         return page;
1280
1281 outside_data_content:
1282         /*
1283          * An external ptracer can access pages that normally aren't
1284          * accessible..
1285          */
1286         if (area->vm_mm == current->mm)
1287                 return NULL;
1288         /* Fall through to the non-read-ahead case */
1289 no_cached_page:
1290         /*
1291          * We're only likely to ever get here if MADV_RANDOM is in
1292          * effect.
1293          */
1294         error = page_cache_read(file, pgoff);
1295         grab_swap_token();
1296
1297         /*
1298          * The page we want has now been added to the page cache.
1299          * In the unlikely event that someone removed it in the
1300          * meantime, we'll just come back here and read it again.
1301          */
1302         if (error >= 0)
1303                 goto retry_find;
1304
1305         /*
1306          * An error return from page_cache_read can result if the
1307          * system is low on memory, or a problem occurs while trying
1308          * to schedule I/O.
1309          */
1310         if (error == -ENOMEM)
1311                 return NOPAGE_OOM;
1312         return NULL;
1313
1314 page_not_uptodate:
1315         if (!did_readaround) {
1316                 majmin = VM_FAULT_MAJOR;
1317                 inc_page_state(pgmajfault);
1318         }
1319         lock_page(page);
1320
1321         /* Did it get unhashed while we waited for it? */
1322         if (!page->mapping) {
1323                 unlock_page(page);
1324                 page_cache_release(page);
1325                 goto retry_all;
1326         }
1327
1328         /* Did somebody else get it up-to-date? */
1329         if (PageUptodate(page)) {
1330                 unlock_page(page);
1331                 goto success;
1332         }
1333
1334         if (!mapping->a_ops->readpage(file, page)) {
1335                 wait_on_page_locked(page);
1336                 if (PageUptodate(page))
1337                         goto success;
1338         }
1339
1340         /*
1341          * Umm, take care of errors if the page isn't up-to-date.
1342          * Try to re-read it _once_. We do this synchronously,
1343          * because there really aren't any performance issues here
1344          * and we need to check for errors.
1345          */
1346         lock_page(page);
1347
1348         /* Somebody truncated the page on us? */
1349         if (!page->mapping) {
1350                 unlock_page(page);
1351                 page_cache_release(page);
1352                 goto retry_all;
1353         }
1354
1355         /* Somebody else successfully read it in? */
1356         if (PageUptodate(page)) {
1357                 unlock_page(page);
1358                 goto success;
1359         }
1360         ClearPageError(page);
1361         if (!mapping->a_ops->readpage(file, page)) {
1362                 wait_on_page_locked(page);
1363                 if (PageUptodate(page))
1364                         goto success;
1365         }
1366
1367         /*
1368          * Things didn't work out. Return zero to tell the
1369          * mm layer so, possibly freeing the page cache page first.
1370          */
1371         page_cache_release(page);
1372         return NULL;
1373 }
1374
1375 EXPORT_SYMBOL(filemap_nopage);
1376
1377 static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1378                                         int nonblock)
1379 {
1380         struct address_space *mapping = file->f_mapping;
1381         struct page *page;
1382         int error;
1383
1384         /*
1385          * Do we have something in the page cache already?
1386          */
1387 retry_find:
1388         page = find_get_page(mapping, pgoff);
1389         if (!page) {
1390                 if (nonblock)
1391                         return NULL;
1392                 goto no_cached_page;
1393         }
1394
1395         /*
1396          * Ok, found a page in the page cache, now we need to check
1397          * that it's up-to-date.
1398          */
1399         if (!PageUptodate(page)) {
1400                 if (nonblock) {
1401                         page_cache_release(page);
1402                         return NULL;
1403                 }
1404                 goto page_not_uptodate;
1405         }
1406
1407 success:
1408         /*
1409          * Found the page and have a reference on it.
1410          */
1411         mark_page_accessed(page);
1412         return page;
1413
1414 no_cached_page:
1415         error = page_cache_read(file, pgoff);
1416
1417         /*
1418          * The page we want has now been added to the page cache.
1419          * In the unlikely event that someone removed it in the
1420          * meantime, we'll just come back here and read it again.
1421          */
1422         if (error >= 0)
1423                 goto retry_find;
1424
1425         /*
1426          * An error return from page_cache_read can result if the
1427          * system is low on memory, or a problem occurs while trying
1428          * to schedule I/O.
1429          */
1430         return NULL;
1431
1432 page_not_uptodate:
1433         lock_page(page);
1434
1435         /* Did it get unhashed while we waited for it? */
1436         if (!page->mapping) {
1437                 unlock_page(page);
1438                 goto err;
1439         }
1440
1441         /* Did somebody else get it up-to-date? */
1442         if (PageUptodate(page)) {
1443                 unlock_page(page);
1444                 goto success;
1445         }
1446
1447         if (!mapping->a_ops->readpage(file, page)) {
1448                 wait_on_page_locked(page);
1449                 if (PageUptodate(page))
1450                         goto success;
1451         }
1452
1453         /*
1454          * Umm, take care of errors if the page isn't up-to-date.
1455          * Try to re-read it _once_. We do this synchronously,
1456          * because there really aren't any performance issues here
1457          * and we need to check for errors.
1458          */
1459         lock_page(page);
1460
1461         /* Somebody truncated the page on us? */
1462         if (!page->mapping) {
1463                 unlock_page(page);
1464                 goto err;
1465         }
1466         /* Somebody else successfully read it in? */
1467         if (PageUptodate(page)) {
1468                 unlock_page(page);
1469                 goto success;
1470         }
1471
1472         ClearPageError(page);
1473         if (!mapping->a_ops->readpage(file, page)) {
1474                 wait_on_page_locked(page);
1475                 if (PageUptodate(page))
1476                         goto success;
1477         }
1478
1479         /*
1480          * Things didn't work out. Return zero to tell the
1481          * mm layer so, possibly freeing the page cache page first.
1482          */
1483 err:
1484         page_cache_release(page);
1485
1486         return NULL;
1487 }
1488
1489 int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1490                 unsigned long len, pgprot_t prot, unsigned long pgoff,
1491                 int nonblock)
1492 {
1493         struct file *file = vma->vm_file;
1494         struct address_space *mapping = file->f_mapping;
1495         struct inode *inode = mapping->host;
1496         unsigned long size;
1497         struct mm_struct *mm = vma->vm_mm;
1498         struct page *page;
1499         int err;
1500
1501         if (!nonblock)
1502                 force_page_cache_readahead(mapping, vma->vm_file,
1503                                         pgoff, len >> PAGE_CACHE_SHIFT);
1504
1505 repeat:
1506         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1507         if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1508                 return -EINVAL;
1509
1510         page = filemap_getpage(file, pgoff, nonblock);
1511         if (!page && !nonblock)
1512                 return -ENOMEM;
1513         if (page) {
1514                 err = install_page(mm, vma, addr, page, prot);
1515                 if (err) {
1516                         page_cache_release(page);
1517                         return err;
1518                 }
1519         } else {
1520                 err = install_file_pte(mm, vma, addr, pgoff, prot);
1521                 if (err)
1522                         return err;
1523         }
1524
1525         len -= PAGE_SIZE;
1526         addr += PAGE_SIZE;
1527         pgoff++;
1528         if (len)
1529                 goto repeat;
1530
1531         return 0;
1532 }
1533
1534 struct vm_operations_struct generic_file_vm_ops = {
1535         .nopage         = filemap_nopage,
1536         .populate       = filemap_populate,
1537 };
1538
1539 /* This is used for a general mmap of a disk file */
1540
1541 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1542 {
1543         struct address_space *mapping = file->f_mapping;
1544
1545         if (!mapping->a_ops->readpage)
1546                 return -ENOEXEC;
1547         file_accessed(file);
1548         vma->vm_ops = &generic_file_vm_ops;
1549         return 0;
1550 }
1551 EXPORT_SYMBOL(filemap_populate);
1552
1553 /*
1554  * This is for filesystems which do not implement ->writepage.
1555  */
1556 int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1557 {
1558         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1559                 return -EINVAL;
1560         return generic_file_mmap(file, vma);
1561 }
1562 #else
1563 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1564 {
1565         return -ENOSYS;
1566 }
1567 int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1568 {
1569         return -ENOSYS;
1570 }
1571 #endif /* CONFIG_MMU */
1572
1573 EXPORT_SYMBOL(generic_file_mmap);
1574 EXPORT_SYMBOL(generic_file_readonly_mmap);
1575
1576 static inline struct page *__read_cache_page(struct address_space *mapping,
1577                                 unsigned long index,
1578                                 int (*filler)(void *,struct page*),
1579                                 void *data)
1580 {
1581         struct page *page, *cached_page = NULL;
1582         int err;
1583 repeat:
1584         page = find_get_page(mapping, index);
1585         if (!page) {
1586                 if (!cached_page) {
1587                         cached_page = page_cache_alloc_cold(mapping);
1588                         if (!cached_page)
1589                                 return ERR_PTR(-ENOMEM);
1590                 }
1591                 err = add_to_page_cache_lru(cached_page, mapping,
1592                                         index, GFP_KERNEL);
1593                 if (err == -EEXIST)
1594                         goto repeat;
1595                 if (err < 0) {
1596                         /* Presumably ENOMEM for radix tree node */
1597                         page_cache_release(cached_page);
1598                         return ERR_PTR(err);
1599                 }
1600                 page = cached_page;
1601                 cached_page = NULL;
1602                 err = filler(data, page);
1603                 if (err < 0) {
1604                         page_cache_release(page);
1605                         page = ERR_PTR(err);
1606                 }
1607         }
1608         if (cached_page)
1609                 page_cache_release(cached_page);
1610         return page;
1611 }
1612
1613 /*
1614  * Read into the page cache. If a page already exists,
1615  * and PageUptodate() is not set, try to fill the page.
1616  */
1617 struct page *read_cache_page(struct address_space *mapping,
1618                                 unsigned long index,
1619                                 int (*filler)(void *,struct page*),
1620                                 void *data)
1621 {
1622         struct page *page;
1623         int err;
1624
1625 retry:
1626         page = __read_cache_page(mapping, index, filler, data);
1627         if (IS_ERR(page))
1628                 goto out;
1629         mark_page_accessed(page);
1630         if (PageUptodate(page))
1631                 goto out;
1632
1633         lock_page(page);
1634         if (!page->mapping) {
1635                 unlock_page(page);
1636                 page_cache_release(page);
1637                 goto retry;
1638         }
1639         if (PageUptodate(page)) {
1640                 unlock_page(page);
1641                 goto out;
1642         }
1643         err = filler(data, page);
1644         if (err < 0) {
1645                 page_cache_release(page);
1646                 page = ERR_PTR(err);
1647         }
1648  out:
1649         return page;
1650 }
1651
1652 EXPORT_SYMBOL(read_cache_page);
1653
1654 /*
1655  * If the page was newly created, increment its refcount and add it to the
1656  * caller's lru-buffering pagevec.  This function is specifically for
1657  * generic_file_write().
1658  */
1659 static inline struct page *
1660 __grab_cache_page(struct address_space *mapping, unsigned long index,
1661                         struct page **cached_page, struct pagevec *lru_pvec)
1662 {
1663         int err;
1664         struct page *page;
1665 repeat:
1666         page = find_lock_page(mapping, index);
1667         if (!page) {
1668                 if (!*cached_page) {
1669                         *cached_page = page_cache_alloc(mapping);
1670                         if (!*cached_page)
1671                                 return NULL;
1672                 }
1673                 err = add_to_page_cache(*cached_page, mapping,
1674                                         index, GFP_KERNEL);
1675                 if (err == -EEXIST)
1676                         goto repeat;
1677                 if (err == 0) {
1678                         page = *cached_page;
1679                         page_cache_get(page);
1680                         if (!pagevec_add(lru_pvec, page))
1681                                 __pagevec_lru_add(lru_pvec);
1682                         *cached_page = NULL;
1683                 }
1684         }
1685         return page;
1686 }
1687
1688 /*
1689  * The logic we want is
1690  *
1691  *      if suid or (sgid and xgrp)
1692  *              remove privs
1693  */
1694 int remove_suid(struct dentry *dentry)
1695 {
1696         mode_t mode = dentry->d_inode->i_mode;
1697         int kill = 0;
1698         int result = 0;
1699
1700         /* suid always must be killed */
1701         if (unlikely(mode & S_ISUID))
1702                 kill = ATTR_KILL_SUID;
1703
1704         /*
1705          * sgid without any exec bits is just a mandatory locking mark; leave
1706          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1707          */
1708         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1709                 kill |= ATTR_KILL_SGID;
1710
1711         if (unlikely(kill && !capable(CAP_FSETID))) {
1712                 struct iattr newattrs;
1713
1714                 newattrs.ia_valid = ATTR_FORCE | kill;
1715                 result = notify_change(dentry, &newattrs);
1716         }
1717         return result;
1718 }
1719 EXPORT_SYMBOL(remove_suid);
1720
1721 /*
1722  * Copy as much as we can into the page and return the number of bytes which
1723  * were sucessfully copied.  If a fault is encountered then clear the page
1724  * out to (offset+bytes) and return the number of bytes which were copied.
1725  */
1726 static inline size_t
1727 filemap_copy_from_user(struct page *page, unsigned long offset,
1728                         const char __user *buf, unsigned bytes)
1729 {
1730         char *kaddr;
1731         int left;
1732
1733         kaddr = kmap_atomic(page, KM_USER0);
1734         left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
1735         kunmap_atomic(kaddr, KM_USER0);
1736
1737         if (left != 0) {
1738                 /* Do it the slow way */
1739                 kaddr = kmap(page);
1740                 left = __copy_from_user(kaddr + offset, buf, bytes);
1741                 kunmap(page);
1742         }
1743         return bytes - left;
1744 }
1745
1746 static size_t
1747 __filemap_copy_from_user_iovec(char *vaddr, 
1748                         const struct iovec *iov, size_t base, size_t bytes)
1749 {
1750         size_t copied = 0, left = 0;
1751
1752         while (bytes) {
1753                 char __user *buf = iov->iov_base + base;
1754                 int copy = min(bytes, iov->iov_len - base);
1755
1756                 base = 0;
1757                 left = __copy_from_user_inatomic(vaddr, buf, copy);
1758                 copied += copy;
1759                 bytes -= copy;
1760                 vaddr += copy;
1761                 iov++;
1762
1763                 if (unlikely(left)) {
1764                         /* zero the rest of the target like __copy_from_user */
1765                         if (bytes)
1766                                 memset(vaddr, 0, bytes);
1767                         break;
1768                 }
1769         }
1770         return copied - left;
1771 }
1772
1773 /*
1774  * This has the same sideeffects and return value as filemap_copy_from_user().
1775  * The difference is that on a fault we need to memset the remainder of the
1776  * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
1777  * single-segment behaviour.
1778  */
1779 static inline size_t
1780 filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
1781                         const struct iovec *iov, size_t base, size_t bytes)
1782 {
1783         char *kaddr;
1784         size_t copied;
1785
1786         kaddr = kmap_atomic(page, KM_USER0);
1787         copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1788                                                 base, bytes);
1789         kunmap_atomic(kaddr, KM_USER0);
1790         if (copied != bytes) {
1791                 kaddr = kmap(page);
1792                 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1793                                                         base, bytes);
1794                 kunmap(page);
1795         }
1796         return copied;
1797 }
1798
1799 static inline void
1800 filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
1801 {
1802         const struct iovec *iov = *iovp;
1803         size_t base = *basep;
1804
1805         while (bytes) {
1806                 int copy = min(bytes, iov->iov_len - base);
1807
1808                 bytes -= copy;
1809                 base += copy;
1810                 if (iov->iov_len == base) {
1811                         iov++;
1812                         base = 0;
1813                 }
1814         }
1815         *iovp = iov;
1816         *basep = base;
1817 }
1818
1819 /*
1820  * Performs necessary checks before doing a write
1821  *
1822  * Can adjust writing position aor amount of bytes to write.
1823  * Returns appropriate error code that caller should return or
1824  * zero in case that write should be allowed.
1825  */
1826 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1827 {
1828         struct inode *inode = file->f_mapping->host;
1829         unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1830
1831         if (unlikely(*pos < 0))
1832                 return -EINVAL;
1833
1834         if (unlikely(file->f_error)) {
1835                 int err = file->f_error;
1836                 file->f_error = 0;
1837                 return err;
1838         }
1839
1840         if (!isblk) {
1841                 /* FIXME: this is for backwards compatibility with 2.4 */
1842                 if (file->f_flags & O_APPEND)
1843                         *pos = i_size_read(inode);
1844
1845                 if (limit != RLIM_INFINITY) {
1846                         if (*pos >= limit) {
1847                                 send_sig(SIGXFSZ, current, 0);
1848                                 return -EFBIG;
1849                         }
1850                         if (*count > limit - (typeof(limit))*pos) {
1851                                 *count = limit - (typeof(limit))*pos;
1852                         }
1853                 }
1854         }
1855
1856         /*
1857          * LFS rule
1858          */
1859         if (unlikely(*pos + *count > MAX_NON_LFS &&
1860                                 !(file->f_flags & O_LARGEFILE))) {
1861                 if (*pos >= MAX_NON_LFS) {
1862                         send_sig(SIGXFSZ, current, 0);
1863                         return -EFBIG;
1864                 }
1865                 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1866                         *count = MAX_NON_LFS - (unsigned long)*pos;
1867                 }
1868         }
1869
1870         /*
1871          * Are we about to exceed the fs block limit ?
1872          *
1873          * If we have written data it becomes a short write.  If we have
1874          * exceeded without writing data we send a signal and return EFBIG.
1875          * Linus frestrict idea will clean these up nicely..
1876          */
1877         if (likely(!isblk)) {
1878                 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1879                         if (*count || *pos > inode->i_sb->s_maxbytes) {
1880                                 send_sig(SIGXFSZ, current, 0);
1881                                 return -EFBIG;
1882                         }
1883                         /* zero-length writes at ->s_maxbytes are OK */
1884                 }
1885
1886                 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1887                         *count = inode->i_sb->s_maxbytes - *pos;
1888         } else {
1889                 loff_t isize;
1890                 if (bdev_read_only(I_BDEV(inode)))
1891                         return -EPERM;
1892                 isize = i_size_read(inode);
1893                 if (*pos >= isize) {
1894                         if (*count || *pos > isize)
1895                                 return -ENOSPC;
1896                 }
1897
1898                 if (*pos + *count > isize)
1899                         *count = isize - *pos;
1900         }
1901         return 0;
1902 }
1903 EXPORT_SYMBOL(generic_write_checks);
1904
1905 ssize_t
1906 generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1907                 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1908                 size_t count, size_t ocount)
1909 {
1910         struct file     *file = iocb->ki_filp;
1911         struct address_space *mapping = file->f_mapping;
1912         struct inode    *inode = mapping->host;
1913         ssize_t         written;
1914
1915         if (count != ocount)
1916                 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1917
1918         written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1919         if (written > 0) {
1920                 loff_t end = pos + written;
1921                 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1922                         i_size_write(inode,  end);
1923                         mark_inode_dirty(inode);
1924                 }
1925                 *ppos = end;
1926         }
1927
1928         /*
1929          * Sync the fs metadata but not the minor inode changes and
1930          * of course not the data as we did direct DMA for the IO.
1931          * i_sem is held, which protects generic_osync_inode() from
1932          * livelocking.
1933          */
1934         if (written >= 0 && file->f_flags & O_SYNC)
1935                 generic_osync_inode(inode, mapping, OSYNC_METADATA);
1936         if (written == count && !is_sync_kiocb(iocb))
1937                 written = -EIOCBQUEUED;
1938         return written;
1939 }
1940 EXPORT_SYMBOL(generic_file_direct_write);
1941
1942 ssize_t
1943 generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1944                 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1945                 size_t count, ssize_t written)
1946 {
1947         struct file *file = iocb->ki_filp;
1948         struct address_space * mapping = file->f_mapping;
1949         struct address_space_operations *a_ops = mapping->a_ops;
1950         struct inode    *inode = mapping->host;
1951         long            status = 0;
1952         struct page     *page;
1953         struct page     *cached_page = NULL;
1954         size_t          bytes;
1955         struct pagevec  lru_pvec;
1956         const struct iovec *cur_iov = iov; /* current iovec */
1957         size_t          iov_base = 0;      /* offset in the current iovec */
1958         char __user     *buf;
1959
1960         pagevec_init(&lru_pvec, 0);
1961
1962         /*
1963          * handle partial DIO write.  Adjust cur_iov if needed.
1964          */
1965         if (likely(nr_segs == 1))
1966                 buf = iov->iov_base + written;
1967         else {
1968                 filemap_set_next_iovec(&cur_iov, &iov_base, written);
1969                 buf = cur_iov->iov_base + iov_base;
1970         }
1971
1972         do {
1973                 unsigned long index;
1974                 unsigned long offset;
1975                 size_t copied;
1976
1977                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1978                 index = pos >> PAGE_CACHE_SHIFT;
1979                 bytes = PAGE_CACHE_SIZE - offset;
1980                 if (bytes > count)
1981                         bytes = count;
1982
1983                 /*
1984                  * Bring in the user page that we will copy from _first_.
1985                  * Otherwise there's a nasty deadlock on copying from the
1986                  * same page as we're writing to, without it being marked
1987                  * up-to-date.
1988                  */
1989                 fault_in_pages_readable(buf, bytes);
1990
1991                 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1992                 if (!page) {
1993                         status = -ENOMEM;
1994                         break;
1995                 }
1996
1997                 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1998                 if (unlikely(status)) {
1999                         loff_t isize = i_size_read(inode);
2000                         /*
2001                          * prepare_write() may have instantiated a few blocks
2002                          * outside i_size.  Trim these off again.
2003                          */
2004                         unlock_page(page);
2005                         page_cache_release(page);
2006                         if (pos + bytes > isize)
2007                                 vmtruncate(inode, isize);
2008                         break;
2009                 }
2010                 if (likely(nr_segs == 1))
2011                         copied = filemap_copy_from_user(page, offset,
2012                                                         buf, bytes);
2013                 else
2014                         copied = filemap_copy_from_user_iovec(page, offset,
2015                                                 cur_iov, iov_base, bytes);
2016                 flush_dcache_page(page);
2017                 status = a_ops->commit_write(file, page, offset, offset+bytes);
2018                 if (likely(copied > 0)) {
2019                         if (!status)
2020                                 status = copied;
2021
2022                         if (status >= 0) {
2023                                 written += status;
2024                                 count -= status;
2025                                 pos += status;
2026                                 buf += status;
2027                                 if (unlikely(nr_segs > 1)) {
2028                                         filemap_set_next_iovec(&cur_iov,
2029                                                         &iov_base, status);
2030                                         buf = cur_iov->iov_base + iov_base;
2031                                 }
2032                         }
2033                 }
2034                 if (unlikely(copied != bytes))
2035                         if (status >= 0)
2036                                 status = -EFAULT;
2037                 unlock_page(page);
2038                 mark_page_accessed(page);
2039                 page_cache_release(page);
2040                 if (status < 0)
2041                         break;
2042                 balance_dirty_pages_ratelimited(mapping);
2043                 cond_resched();
2044         } while (count);
2045         *ppos = pos;
2046
2047         if (cached_page)
2048                 page_cache_release(cached_page);
2049
2050         /*
2051          * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2052          */
2053         if (likely(status >= 0)) {
2054                 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2055                         if (!a_ops->writepage || !is_sync_kiocb(iocb))
2056                                 status = generic_osync_inode(inode, mapping,
2057                                                 OSYNC_METADATA|OSYNC_DATA);
2058                 }
2059         }
2060         
2061         /*
2062          * If we get here for O_DIRECT writes then we must have fallen through
2063          * to buffered writes (block instantiation inside i_size).  So we sync
2064          * the file data here, to try to honour O_DIRECT expectations.
2065          */
2066         if (unlikely(file->f_flags & O_DIRECT) && written)
2067                 status = filemap_write_and_wait(mapping);
2068
2069         pagevec_lru_add(&lru_pvec);
2070         return written ? written : status;
2071 }
2072 EXPORT_SYMBOL(generic_file_buffered_write);
2073
2074 ssize_t
2075 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2076                                 unsigned long nr_segs, loff_t *ppos)
2077 {
2078         struct file *file = iocb->ki_filp;
2079         struct address_space * mapping = file->f_mapping;
2080         size_t ocount;          /* original count */
2081         size_t count;           /* after file limit checks */
2082         struct inode    *inode = mapping->host;
2083         unsigned long   seg;
2084         loff_t          pos;
2085         ssize_t         written;
2086         ssize_t         err;
2087
2088         ocount = 0;
2089         for (seg = 0; seg < nr_segs; seg++) {
2090                 const struct iovec *iv = &iov[seg];
2091
2092                 /*
2093                  * If any segment has a negative length, or the cumulative
2094                  * length ever wraps negative then return -EINVAL.
2095                  */
2096                 ocount += iv->iov_len;
2097                 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2098                         return -EINVAL;
2099                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2100                         continue;
2101                 if (seg == 0)
2102                         return -EFAULT;
2103                 nr_segs = seg;
2104                 ocount -= iv->iov_len;  /* This segment is no good */
2105                 break;
2106         }
2107
2108         count = ocount;
2109         pos = *ppos;
2110
2111         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2112
2113         /* We can write back this queue in page reclaim */
2114         current->backing_dev_info = mapping->backing_dev_info;
2115         written = 0;
2116
2117         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2118         if (err)
2119                 goto out;
2120
2121         if (count == 0)
2122                 goto out;
2123
2124         err = remove_suid(file->f_dentry);
2125         if (err)
2126                 goto out;
2127
2128         inode_update_time(inode, 1);
2129
2130         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2131         if (unlikely(file->f_flags & O_DIRECT)) {
2132                 written = generic_file_direct_write(iocb, iov,
2133                                 &nr_segs, pos, ppos, count, ocount);
2134                 if (written < 0 || written == count)
2135                         goto out;
2136                 /*
2137                  * direct-io write to a hole: fall through to buffered I/O
2138                  * for completing the rest of the request.
2139                  */
2140                 pos += written;
2141                 count -= written;
2142         }
2143
2144         written = generic_file_buffered_write(iocb, iov, nr_segs,
2145                         pos, ppos, count, written);
2146 out:
2147         current->backing_dev_info = NULL;
2148         return written ? written : err;
2149 }
2150 EXPORT_SYMBOL(generic_file_aio_write_nolock);
2151
2152 ssize_t
2153 generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2154                                 unsigned long nr_segs, loff_t *ppos)
2155 {
2156         struct file *file = iocb->ki_filp;
2157         struct address_space *mapping = file->f_mapping;
2158         struct inode *inode = mapping->host;
2159         ssize_t ret;
2160         loff_t pos = *ppos;
2161
2162         ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2163
2164         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2165                 int err;
2166
2167                 err = sync_page_range_nolock(inode, mapping, pos, ret);
2168                 if (err < 0)
2169                         ret = err;
2170         }
2171         return ret;
2172 }
2173
2174 ssize_t
2175 __generic_file_write_nolock(struct file *file, const struct iovec *iov,
2176                                 unsigned long nr_segs, loff_t *ppos)
2177 {
2178         struct kiocb kiocb;
2179         ssize_t ret;
2180
2181         init_sync_kiocb(&kiocb, file);
2182         ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2183         if (ret == -EIOCBQUEUED)
2184                 ret = wait_on_sync_kiocb(&kiocb);
2185         return ret;
2186 }
2187
2188 ssize_t
2189 generic_file_write_nolock(struct file *file, const struct iovec *iov,
2190                                 unsigned long nr_segs, loff_t *ppos)
2191 {
2192         struct kiocb kiocb;
2193         ssize_t ret;
2194
2195         init_sync_kiocb(&kiocb, file);
2196         ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2197         if (-EIOCBQUEUED == ret)
2198                 ret = wait_on_sync_kiocb(&kiocb);
2199         return ret;
2200 }
2201 EXPORT_SYMBOL(generic_file_write_nolock);
2202
2203 ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2204                                size_t count, loff_t pos)
2205 {
2206         struct file *file = iocb->ki_filp;
2207         struct address_space *mapping = file->f_mapping;
2208         struct inode *inode = mapping->host;
2209         ssize_t ret;
2210         struct iovec local_iov = { .iov_base = (void __user *)buf,
2211                                         .iov_len = count };
2212
2213         BUG_ON(iocb->ki_pos != pos);
2214
2215         down(&inode->i_sem);
2216         ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2217                                                 &iocb->ki_pos);
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, pos, ret);
2224                 if (err < 0)
2225                         ret = err;
2226         }
2227         return ret;
2228 }
2229 EXPORT_SYMBOL(generic_file_aio_write);
2230
2231 ssize_t generic_file_write(struct file *file, const char __user *buf,
2232                            size_t count, loff_t *ppos)
2233 {
2234         struct address_space *mapping = file->f_mapping;
2235         struct inode *inode = mapping->host;
2236         ssize_t ret;
2237         struct iovec local_iov = { .iov_base = (void __user *)buf,
2238                                         .iov_len = count };
2239
2240         down(&inode->i_sem);
2241         ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2242         up(&inode->i_sem);
2243
2244         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2245                 ssize_t err;
2246
2247                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2248                 if (err < 0)
2249                         ret = err;
2250         }
2251         return ret;
2252 }
2253 EXPORT_SYMBOL(generic_file_write);
2254
2255 ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2256                         unsigned long nr_segs, loff_t *ppos)
2257 {
2258         struct kiocb kiocb;
2259         ssize_t ret;
2260
2261         init_sync_kiocb(&kiocb, filp);
2262         ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2263         if (-EIOCBQUEUED == ret)
2264                 ret = wait_on_sync_kiocb(&kiocb);
2265         return ret;
2266 }
2267 EXPORT_SYMBOL(generic_file_readv);
2268
2269 ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2270                         unsigned long nr_segs, loff_t *ppos)
2271 {
2272         struct address_space *mapping = file->f_mapping;
2273         struct inode *inode = mapping->host;
2274         ssize_t ret;
2275
2276         down(&inode->i_sem);
2277         ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2278         up(&inode->i_sem);
2279
2280         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2281                 int err;
2282
2283                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2284                 if (err < 0)
2285                         ret = err;
2286         }
2287         return ret;
2288 }
2289 EXPORT_SYMBOL(generic_file_writev);
2290
2291 /*
2292  * Called under i_sem for writes to S_ISREG files.   Returns -EIO if something
2293  * went wrong during pagecache shootdown.
2294  */
2295 ssize_t
2296 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2297         loff_t offset, unsigned long nr_segs)
2298 {
2299         struct file *file = iocb->ki_filp;
2300         struct address_space *mapping = file->f_mapping;
2301         ssize_t retval;
2302         size_t write_len = 0;
2303
2304         /*
2305          * If it's a write, unmap all mmappings of the file up-front.  This
2306          * will cause any pte dirty bits to be propagated into the pageframes
2307          * for the subsequent filemap_write_and_wait().
2308          */
2309         if (rw == WRITE) {
2310                 write_len = iov_length(iov, nr_segs);
2311                 if (mapping_mapped(mapping))
2312                         unmap_mapping_range(mapping, offset, write_len, 0);
2313         }
2314
2315         retval = filemap_write_and_wait(mapping);
2316         if (retval == 0) {
2317                 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2318                                                 offset, nr_segs);
2319                 if (rw == WRITE && mapping->nrpages) {
2320                         pgoff_t end = (offset + write_len - 1)
2321                                                 >> PAGE_CACHE_SHIFT;
2322                         int err = invalidate_inode_pages2_range(mapping,
2323                                         offset >> PAGE_CACHE_SHIFT, end);
2324                         if (err)
2325                                 retval = err;
2326                 }
2327         }
2328         return retval;
2329 }
2330 EXPORT_SYMBOL_GPL(generic_file_direct_IO);