[PATCH] Prepare for __copy_from_user_inatomic to not zero missed bytes
[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/uaccess.h>
18 #include <linux/aio.h>
19 #include <linux/capability.h>
20 #include <linux/kernel_stat.h>
21 #include <linux/mm.h>
22 #include <linux/swap.h>
23 #include <linux/mman.h>
24 #include <linux/pagemap.h>
25 #include <linux/file.h>
26 #include <linux/uio.h>
27 #include <linux/hash.h>
28 #include <linux/writeback.h>
29 #include <linux/pagevec.h>
30 #include <linux/blkdev.h>
31 #include <linux/security.h>
32 #include <linux/syscalls.h>
33 #include <linux/cpuset.h>
34 #include "filemap.h"
35 #include "internal.h"
36
37 /*
38  * FIXME: remove all knowledge of the buffer layer from the core VM
39  */
40 #include <linux/buffer_head.h> /* for generic_osync_inode */
41
42 #include <asm/mman.h>
43
44 static ssize_t
45 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
46         loff_t offset, unsigned long nr_segs);
47
48 /*
49  * Shared mappings implemented 30.11.1994. It's not fully working yet,
50  * though.
51  *
52  * Shared mappings now work. 15.8.1995  Bruno.
53  *
54  * finished 'unifying' the page and buffer cache and SMP-threaded the
55  * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
56  *
57  * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
58  */
59
60 /*
61  * Lock ordering:
62  *
63  *  ->i_mmap_lock               (vmtruncate)
64  *    ->private_lock            (__free_pte->__set_page_dirty_buffers)
65  *      ->swap_lock             (exclusive_swap_page, others)
66  *        ->mapping->tree_lock
67  *
68  *  ->i_mutex
69  *    ->i_mmap_lock             (truncate->unmap_mapping_range)
70  *
71  *  ->mmap_sem
72  *    ->i_mmap_lock
73  *      ->page_table_lock or pte_lock   (various, mainly in memory.c)
74  *        ->mapping->tree_lock  (arch-dependent flush_dcache_mmap_lock)
75  *
76  *  ->mmap_sem
77  *    ->lock_page               (access_process_vm)
78  *
79  *  ->mmap_sem
80  *    ->i_mutex                 (msync)
81  *
82  *  ->i_mutex
83  *    ->i_alloc_sem             (various)
84  *
85  *  ->inode_lock
86  *    ->sb_lock                 (fs/fs-writeback.c)
87  *    ->mapping->tree_lock      (__sync_single_inode)
88  *
89  *  ->i_mmap_lock
90  *    ->anon_vma.lock           (vma_adjust)
91  *
92  *  ->anon_vma.lock
93  *    ->page_table_lock or pte_lock     (anon_vma_prepare and various)
94  *
95  *  ->page_table_lock or pte_lock
96  *    ->swap_lock               (try_to_unmap_one)
97  *    ->private_lock            (try_to_unmap_one)
98  *    ->tree_lock               (try_to_unmap_one)
99  *    ->zone.lru_lock           (follow_page->mark_page_accessed)
100  *    ->zone.lru_lock           (check_pte_range->isolate_lru_page)
101  *    ->private_lock            (page_remove_rmap->set_page_dirty)
102  *    ->tree_lock               (page_remove_rmap->set_page_dirty)
103  *    ->inode_lock              (page_remove_rmap->set_page_dirty)
104  *    ->inode_lock              (zap_pte_range->set_page_dirty)
105  *    ->private_lock            (zap_pte_range->__set_page_dirty_buffers)
106  *
107  *  ->task->proc_lock
108  *    ->dcache_lock             (proc_pid_lookup)
109  */
110
111 /*
112  * Remove a page from the page cache and free it. Caller has to make
113  * sure the page is locked and that nobody else uses it - or that usage
114  * is safe.  The caller must hold a write_lock on the mapping's tree_lock.
115  */
116 void __remove_from_page_cache(struct page *page)
117 {
118         struct address_space *mapping = page->mapping;
119
120         radix_tree_delete(&mapping->page_tree, page->index);
121         page->mapping = NULL;
122         mapping->nrpages--;
123         pagecache_acct(-1);
124 }
125
126 void remove_from_page_cache(struct page *page)
127 {
128         struct address_space *mapping = page->mapping;
129
130         BUG_ON(!PageLocked(page));
131
132         write_lock_irq(&mapping->tree_lock);
133         __remove_from_page_cache(page);
134         write_unlock_irq(&mapping->tree_lock);
135 }
136
137 static int sync_page(void *word)
138 {
139         struct address_space *mapping;
140         struct page *page;
141
142         page = container_of((unsigned long *)word, struct page, flags);
143
144         /*
145          * page_mapping() is being called without PG_locked held.
146          * Some knowledge of the state and use of the page is used to
147          * reduce the requirements down to a memory barrier.
148          * The danger here is of a stale page_mapping() return value
149          * indicating a struct address_space different from the one it's
150          * associated with when it is associated with one.
151          * After smp_mb(), it's either the correct page_mapping() for
152          * the page, or an old page_mapping() and the page's own
153          * page_mapping() has gone NULL.
154          * The ->sync_page() address_space operation must tolerate
155          * page_mapping() going NULL. By an amazing coincidence,
156          * this comes about because none of the users of the page
157          * in the ->sync_page() methods make essential use of the
158          * page_mapping(), merely passing the page down to the backing
159          * device's unplug functions when it's non-NULL, which in turn
160          * ignore it for all cases but swap, where only page_private(page) is
161          * of interest. When page_mapping() does go NULL, the entire
162          * call stack gracefully ignores the page and returns.
163          * -- wli
164          */
165         smp_mb();
166         mapping = page_mapping(page);
167         if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
168                 mapping->a_ops->sync_page(page);
169         io_schedule();
170         return 0;
171 }
172
173 /**
174  * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
175  * @mapping:    address space structure to write
176  * @start:      offset in bytes where the range starts
177  * @end:        offset in bytes where the range ends (inclusive)
178  * @sync_mode:  enable synchronous operation
179  *
180  * Start writeback against all of a mapping's dirty pages that lie
181  * within the byte offsets <start, end> inclusive.
182  *
183  * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
184  * opposed to a regular memory cleansing writeback.  The difference between
185  * these two operations is that if a dirty page/buffer is encountered, it must
186  * be waited upon, and not just skipped over.
187  */
188 int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
189                                 loff_t end, int sync_mode)
190 {
191         int ret;
192         struct writeback_control wbc = {
193                 .sync_mode = sync_mode,
194                 .nr_to_write = mapping->nrpages * 2,
195                 .range_start = start,
196                 .range_end = end,
197         };
198
199         if (!mapping_cap_writeback_dirty(mapping))
200                 return 0;
201
202         ret = do_writepages(mapping, &wbc);
203         return ret;
204 }
205
206 static inline int __filemap_fdatawrite(struct address_space *mapping,
207         int sync_mode)
208 {
209         return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
210 }
211
212 int filemap_fdatawrite(struct address_space *mapping)
213 {
214         return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
215 }
216 EXPORT_SYMBOL(filemap_fdatawrite);
217
218 static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
219                                 loff_t end)
220 {
221         return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
222 }
223
224 /**
225  * filemap_flush - mostly a non-blocking flush
226  * @mapping:    target address_space
227  *
228  * This is a mostly non-blocking flush.  Not suitable for data-integrity
229  * purposes - I/O may not be started against all dirty pages.
230  */
231 int filemap_flush(struct address_space *mapping)
232 {
233         return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
234 }
235 EXPORT_SYMBOL(filemap_flush);
236
237 /**
238  * wait_on_page_writeback_range - wait for writeback to complete
239  * @mapping:    target address_space
240  * @start:      beginning page index
241  * @end:        ending page index
242  *
243  * Wait for writeback to complete against pages indexed by start->end
244  * inclusive
245  */
246 int wait_on_page_writeback_range(struct address_space *mapping,
247                                 pgoff_t start, pgoff_t end)
248 {
249         struct pagevec pvec;
250         int nr_pages;
251         int ret = 0;
252         pgoff_t index;
253
254         if (end < start)
255                 return 0;
256
257         pagevec_init(&pvec, 0);
258         index = start;
259         while ((index <= end) &&
260                         (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
261                         PAGECACHE_TAG_WRITEBACK,
262                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
263                 unsigned i;
264
265                 for (i = 0; i < nr_pages; i++) {
266                         struct page *page = pvec.pages[i];
267
268                         /* until radix tree lookup accepts end_index */
269                         if (page->index > end)
270                                 continue;
271
272                         wait_on_page_writeback(page);
273                         if (PageError(page))
274                                 ret = -EIO;
275                 }
276                 pagevec_release(&pvec);
277                 cond_resched();
278         }
279
280         /* Check for outstanding write errors */
281         if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
282                 ret = -ENOSPC;
283         if (test_and_clear_bit(AS_EIO, &mapping->flags))
284                 ret = -EIO;
285
286         return ret;
287 }
288
289 /**
290  * sync_page_range - write and wait on all pages in the passed range
291  * @inode:      target inode
292  * @mapping:    target address_space
293  * @pos:        beginning offset in pages to write
294  * @count:      number of bytes to write
295  *
296  * Write and wait upon all the pages in the passed range.  This is a "data
297  * integrity" operation.  It waits upon in-flight writeout before starting and
298  * waiting upon new writeout.  If there was an IO error, return it.
299  *
300  * We need to re-take i_mutex during the generic_osync_inode list walk because
301  * it is otherwise livelockable.
302  */
303 int sync_page_range(struct inode *inode, struct address_space *mapping,
304                         loff_t pos, loff_t count)
305 {
306         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
307         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
308         int ret;
309
310         if (!mapping_cap_writeback_dirty(mapping) || !count)
311                 return 0;
312         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
313         if (ret == 0) {
314                 mutex_lock(&inode->i_mutex);
315                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
316                 mutex_unlock(&inode->i_mutex);
317         }
318         if (ret == 0)
319                 ret = wait_on_page_writeback_range(mapping, start, end);
320         return ret;
321 }
322 EXPORT_SYMBOL(sync_page_range);
323
324 /**
325  * sync_page_range_nolock
326  * @inode:      target inode
327  * @mapping:    target address_space
328  * @pos:        beginning offset in pages to write
329  * @count:      number of bytes to write
330  *
331  * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
332  * as it forces O_SYNC writers to different parts of the same file
333  * to be serialised right until io completion.
334  */
335 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
336                            loff_t pos, loff_t count)
337 {
338         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
339         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
340         int ret;
341
342         if (!mapping_cap_writeback_dirty(mapping) || !count)
343                 return 0;
344         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
345         if (ret == 0)
346                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
347         if (ret == 0)
348                 ret = wait_on_page_writeback_range(mapping, start, end);
349         return ret;
350 }
351 EXPORT_SYMBOL(sync_page_range_nolock);
352
353 /**
354  * filemap_fdatawait - wait for all under-writeback pages to complete
355  * @mapping: address space structure to wait for
356  *
357  * Walk the list of under-writeback pages of the given address space
358  * and wait for all of them.
359  */
360 int filemap_fdatawait(struct address_space *mapping)
361 {
362         loff_t i_size = i_size_read(mapping->host);
363
364         if (i_size == 0)
365                 return 0;
366
367         return wait_on_page_writeback_range(mapping, 0,
368                                 (i_size - 1) >> PAGE_CACHE_SHIFT);
369 }
370 EXPORT_SYMBOL(filemap_fdatawait);
371
372 int filemap_write_and_wait(struct address_space *mapping)
373 {
374         int err = 0;
375
376         if (mapping->nrpages) {
377                 err = filemap_fdatawrite(mapping);
378                 /*
379                  * Even if the above returned error, the pages may be
380                  * written partially (e.g. -ENOSPC), so we wait for it.
381                  * But the -EIO is special case, it may indicate the worst
382                  * thing (e.g. bug) happened, so we avoid waiting for it.
383                  */
384                 if (err != -EIO) {
385                         int err2 = filemap_fdatawait(mapping);
386                         if (!err)
387                                 err = err2;
388                 }
389         }
390         return err;
391 }
392 EXPORT_SYMBOL(filemap_write_and_wait);
393
394 /**
395  * filemap_write_and_wait_range - write out & wait on a file range
396  * @mapping:    the address_space for the pages
397  * @lstart:     offset in bytes where the range starts
398  * @lend:       offset in bytes where the range ends (inclusive)
399  *
400  * Write out and wait upon file offsets lstart->lend, inclusive.
401  *
402  * Note that `lend' is inclusive (describes the last byte to be written) so
403  * that this function can be used to write to the very end-of-file (end = -1).
404  */
405 int filemap_write_and_wait_range(struct address_space *mapping,
406                                  loff_t lstart, loff_t lend)
407 {
408         int err = 0;
409
410         if (mapping->nrpages) {
411                 err = __filemap_fdatawrite_range(mapping, lstart, lend,
412                                                  WB_SYNC_ALL);
413                 /* See comment of filemap_write_and_wait() */
414                 if (err != -EIO) {
415                         int err2 = wait_on_page_writeback_range(mapping,
416                                                 lstart >> PAGE_CACHE_SHIFT,
417                                                 lend >> PAGE_CACHE_SHIFT);
418                         if (!err)
419                                 err = err2;
420                 }
421         }
422         return err;
423 }
424
425 /**
426  * add_to_page_cache - add newly allocated pagecache pages
427  * @page:       page to add
428  * @mapping:    the page's address_space
429  * @offset:     page index
430  * @gfp_mask:   page allocation mode
431  *
432  * This function is used to add newly allocated pagecache pages;
433  * the page is new, so we can just run SetPageLocked() against it.
434  * The other page state flags were set by rmqueue().
435  *
436  * This function does not add the page to the LRU.  The caller must do that.
437  */
438 int add_to_page_cache(struct page *page, struct address_space *mapping,
439                 pgoff_t offset, gfp_t gfp_mask)
440 {
441         int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
442
443         if (error == 0) {
444                 write_lock_irq(&mapping->tree_lock);
445                 error = radix_tree_insert(&mapping->page_tree, offset, page);
446                 if (!error) {
447                         page_cache_get(page);
448                         SetPageLocked(page);
449                         page->mapping = mapping;
450                         page->index = offset;
451                         mapping->nrpages++;
452                         pagecache_acct(1);
453                 }
454                 write_unlock_irq(&mapping->tree_lock);
455                 radix_tree_preload_end();
456         }
457         return error;
458 }
459 EXPORT_SYMBOL(add_to_page_cache);
460
461 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
462                                 pgoff_t offset, gfp_t gfp_mask)
463 {
464         int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
465         if (ret == 0)
466                 lru_cache_add(page);
467         return ret;
468 }
469
470 #ifdef CONFIG_NUMA
471 struct page *page_cache_alloc(struct address_space *x)
472 {
473         if (cpuset_do_page_mem_spread()) {
474                 int n = cpuset_mem_spread_node();
475                 return alloc_pages_node(n, mapping_gfp_mask(x), 0);
476         }
477         return alloc_pages(mapping_gfp_mask(x), 0);
478 }
479 EXPORT_SYMBOL(page_cache_alloc);
480
481 struct page *page_cache_alloc_cold(struct address_space *x)
482 {
483         if (cpuset_do_page_mem_spread()) {
484                 int n = cpuset_mem_spread_node();
485                 return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
486         }
487         return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
488 }
489 EXPORT_SYMBOL(page_cache_alloc_cold);
490 #endif
491
492 /*
493  * In order to wait for pages to become available there must be
494  * waitqueues associated with pages. By using a hash table of
495  * waitqueues where the bucket discipline is to maintain all
496  * waiters on the same queue and wake all when any of the pages
497  * become available, and for the woken contexts to check to be
498  * sure the appropriate page became available, this saves space
499  * at a cost of "thundering herd" phenomena during rare hash
500  * collisions.
501  */
502 static wait_queue_head_t *page_waitqueue(struct page *page)
503 {
504         const struct zone *zone = page_zone(page);
505
506         return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
507 }
508
509 static inline void wake_up_page(struct page *page, int bit)
510 {
511         __wake_up_bit(page_waitqueue(page), &page->flags, bit);
512 }
513
514 void fastcall wait_on_page_bit(struct page *page, int bit_nr)
515 {
516         DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
517
518         if (test_bit(bit_nr, &page->flags))
519                 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
520                                                         TASK_UNINTERRUPTIBLE);
521 }
522 EXPORT_SYMBOL(wait_on_page_bit);
523
524 /**
525  * unlock_page - unlock a locked page
526  * @page: the page
527  *
528  * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
529  * Also wakes sleepers in wait_on_page_writeback() because the wakeup
530  * mechananism between PageLocked pages and PageWriteback pages is shared.
531  * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
532  *
533  * The first mb is necessary to safely close the critical section opened by the
534  * TestSetPageLocked(), the second mb is necessary to enforce ordering between
535  * the clear_bit and the read of the waitqueue (to avoid SMP races with a
536  * parallel wait_on_page_locked()).
537  */
538 void fastcall unlock_page(struct page *page)
539 {
540         smp_mb__before_clear_bit();
541         if (!TestClearPageLocked(page))
542                 BUG();
543         smp_mb__after_clear_bit(); 
544         wake_up_page(page, PG_locked);
545 }
546 EXPORT_SYMBOL(unlock_page);
547
548 /**
549  * end_page_writeback - end writeback against a page
550  * @page: the page
551  */
552 void end_page_writeback(struct page *page)
553 {
554         if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
555                 if (!test_clear_page_writeback(page))
556                         BUG();
557         }
558         smp_mb__after_clear_bit();
559         wake_up_page(page, PG_writeback);
560 }
561 EXPORT_SYMBOL(end_page_writeback);
562
563 /**
564  * __lock_page - get a lock on the page, assuming we need to sleep to get it
565  * @page: the page to lock
566  *
567  * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary.  If some
568  * random driver's requestfn sets TASK_RUNNING, we could busywait.  However
569  * chances are that on the second loop, the block layer's plug list is empty,
570  * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
571  */
572 void fastcall __lock_page(struct page *page)
573 {
574         DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
575
576         __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
577                                                         TASK_UNINTERRUPTIBLE);
578 }
579 EXPORT_SYMBOL(__lock_page);
580
581 /**
582  * find_get_page - find and get a page reference
583  * @mapping: the address_space to search
584  * @offset: the page index
585  *
586  * A rather lightweight function, finding and getting a reference to a
587  * hashed page atomically.
588  */
589 struct page * find_get_page(struct address_space *mapping, unsigned long offset)
590 {
591         struct page *page;
592
593         read_lock_irq(&mapping->tree_lock);
594         page = radix_tree_lookup(&mapping->page_tree, offset);
595         if (page)
596                 page_cache_get(page);
597         read_unlock_irq(&mapping->tree_lock);
598         return page;
599 }
600 EXPORT_SYMBOL(find_get_page);
601
602 /**
603  * find_trylock_page - find and lock a page
604  * @mapping: the address_space to search
605  * @offset: the page index
606  *
607  * Same as find_get_page(), but trylock it instead of incrementing the count.
608  */
609 struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
610 {
611         struct page *page;
612
613         read_lock_irq(&mapping->tree_lock);
614         page = radix_tree_lookup(&mapping->page_tree, offset);
615         if (page && TestSetPageLocked(page))
616                 page = NULL;
617         read_unlock_irq(&mapping->tree_lock);
618         return page;
619 }
620 EXPORT_SYMBOL(find_trylock_page);
621
622 /**
623  * find_lock_page - locate, pin and lock a pagecache page
624  * @mapping: the address_space to search
625  * @offset: the page index
626  *
627  * Locates the desired pagecache page, locks it, increments its reference
628  * count and returns its address.
629  *
630  * Returns zero if the page was not present. find_lock_page() may sleep.
631  */
632 struct page *find_lock_page(struct address_space *mapping,
633                                 unsigned long offset)
634 {
635         struct page *page;
636
637         read_lock_irq(&mapping->tree_lock);
638 repeat:
639         page = radix_tree_lookup(&mapping->page_tree, offset);
640         if (page) {
641                 page_cache_get(page);
642                 if (TestSetPageLocked(page)) {
643                         read_unlock_irq(&mapping->tree_lock);
644                         __lock_page(page);
645                         read_lock_irq(&mapping->tree_lock);
646
647                         /* Has the page been truncated while we slept? */
648                         if (unlikely(page->mapping != mapping ||
649                                      page->index != offset)) {
650                                 unlock_page(page);
651                                 page_cache_release(page);
652                                 goto repeat;
653                         }
654                 }
655         }
656         read_unlock_irq(&mapping->tree_lock);
657         return page;
658 }
659 EXPORT_SYMBOL(find_lock_page);
660
661 /**
662  * find_or_create_page - locate or add a pagecache page
663  * @mapping: the page's address_space
664  * @index: the page's index into the mapping
665  * @gfp_mask: page allocation mode
666  *
667  * Locates a page in the pagecache.  If the page is not present, a new page
668  * is allocated using @gfp_mask and is added to the pagecache and to the VM's
669  * LRU list.  The returned page is locked and has its reference count
670  * incremented.
671  *
672  * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
673  * allocation!
674  *
675  * find_or_create_page() returns the desired page's address, or zero on
676  * memory exhaustion.
677  */
678 struct page *find_or_create_page(struct address_space *mapping,
679                 unsigned long index, gfp_t gfp_mask)
680 {
681         struct page *page, *cached_page = NULL;
682         int err;
683 repeat:
684         page = find_lock_page(mapping, index);
685         if (!page) {
686                 if (!cached_page) {
687                         cached_page = alloc_page(gfp_mask);
688                         if (!cached_page)
689                                 return NULL;
690                 }
691                 err = add_to_page_cache_lru(cached_page, mapping,
692                                         index, gfp_mask);
693                 if (!err) {
694                         page = cached_page;
695                         cached_page = NULL;
696                 } else if (err == -EEXIST)
697                         goto repeat;
698         }
699         if (cached_page)
700                 page_cache_release(cached_page);
701         return page;
702 }
703 EXPORT_SYMBOL(find_or_create_page);
704
705 /**
706  * find_get_pages - gang pagecache lookup
707  * @mapping:    The address_space to search
708  * @start:      The starting page index
709  * @nr_pages:   The maximum number of pages
710  * @pages:      Where the resulting pages are placed
711  *
712  * find_get_pages() will search for and return a group of up to
713  * @nr_pages pages in the mapping.  The pages are placed at @pages.
714  * find_get_pages() takes a reference against the returned pages.
715  *
716  * The search returns a group of mapping-contiguous pages with ascending
717  * indexes.  There may be holes in the indices due to not-present pages.
718  *
719  * find_get_pages() returns the number of pages which were found.
720  */
721 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
722                             unsigned int nr_pages, struct page **pages)
723 {
724         unsigned int i;
725         unsigned int ret;
726
727         read_lock_irq(&mapping->tree_lock);
728         ret = radix_tree_gang_lookup(&mapping->page_tree,
729                                 (void **)pages, start, nr_pages);
730         for (i = 0; i < ret; i++)
731                 page_cache_get(pages[i]);
732         read_unlock_irq(&mapping->tree_lock);
733         return ret;
734 }
735
736 /**
737  * find_get_pages_contig - gang contiguous pagecache lookup
738  * @mapping:    The address_space to search
739  * @index:      The starting page index
740  * @nr_pages:   The maximum number of pages
741  * @pages:      Where the resulting pages are placed
742  *
743  * find_get_pages_contig() works exactly like find_get_pages(), except
744  * that the returned number of pages are guaranteed to be contiguous.
745  *
746  * find_get_pages_contig() returns the number of pages which were found.
747  */
748 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
749                                unsigned int nr_pages, struct page **pages)
750 {
751         unsigned int i;
752         unsigned int ret;
753
754         read_lock_irq(&mapping->tree_lock);
755         ret = radix_tree_gang_lookup(&mapping->page_tree,
756                                 (void **)pages, index, nr_pages);
757         for (i = 0; i < ret; i++) {
758                 if (pages[i]->mapping == NULL || pages[i]->index != index)
759                         break;
760
761                 page_cache_get(pages[i]);
762                 index++;
763         }
764         read_unlock_irq(&mapping->tree_lock);
765         return i;
766 }
767
768 /**
769  * find_get_pages_tag - find and return pages that match @tag
770  * @mapping:    the address_space to search
771  * @index:      the starting page index
772  * @tag:        the tag index
773  * @nr_pages:   the maximum number of pages
774  * @pages:      where the resulting pages are placed
775  *
776  * Like find_get_pages, except we only return pages which are tagged with
777  * @tag.   We update @index to index the next page for the traversal.
778  */
779 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
780                         int tag, unsigned int nr_pages, struct page **pages)
781 {
782         unsigned int i;
783         unsigned int ret;
784
785         read_lock_irq(&mapping->tree_lock);
786         ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
787                                 (void **)pages, *index, nr_pages, tag);
788         for (i = 0; i < ret; i++)
789                 page_cache_get(pages[i]);
790         if (ret)
791                 *index = pages[ret - 1]->index + 1;
792         read_unlock_irq(&mapping->tree_lock);
793         return ret;
794 }
795
796 /**
797  * grab_cache_page_nowait - returns locked page at given index in given cache
798  * @mapping: target address_space
799  * @index: the page index
800  *
801  * Same as grab_cache_page, but do not wait if the page is unavailable.
802  * This is intended for speculative data generators, where the data can
803  * be regenerated if the page couldn't be grabbed.  This routine should
804  * be safe to call while holding the lock for another page.
805  *
806  * Clear __GFP_FS when allocating the page to avoid recursion into the fs
807  * and deadlock against the caller's locked page.
808  */
809 struct page *
810 grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
811 {
812         struct page *page = find_get_page(mapping, index);
813         gfp_t gfp_mask;
814
815         if (page) {
816                 if (!TestSetPageLocked(page))
817                         return page;
818                 page_cache_release(page);
819                 return NULL;
820         }
821         gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
822         page = alloc_pages(gfp_mask, 0);
823         if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
824                 page_cache_release(page);
825                 page = NULL;
826         }
827         return page;
828 }
829 EXPORT_SYMBOL(grab_cache_page_nowait);
830
831 /**
832  * do_generic_mapping_read - generic file read routine
833  * @mapping:    address_space to be read
834  * @_ra:        file's readahead state
835  * @filp:       the file to read
836  * @ppos:       current file position
837  * @desc:       read_descriptor
838  * @actor:      read method
839  *
840  * This is a generic file read routine, and uses the
841  * mapping->a_ops->readpage() function for the actual low-level stuff.
842  *
843  * This is really ugly. But the goto's actually try to clarify some
844  * of the logic when it comes to error handling etc.
845  *
846  * Note the struct file* is only passed for the use of readpage.
847  * It may be NULL.
848  */
849 void do_generic_mapping_read(struct address_space *mapping,
850                              struct file_ra_state *_ra,
851                              struct file *filp,
852                              loff_t *ppos,
853                              read_descriptor_t *desc,
854                              read_actor_t actor)
855 {
856         struct inode *inode = mapping->host;
857         unsigned long index;
858         unsigned long end_index;
859         unsigned long offset;
860         unsigned long last_index;
861         unsigned long next_index;
862         unsigned long prev_index;
863         loff_t isize;
864         struct page *cached_page;
865         int error;
866         struct file_ra_state ra = *_ra;
867
868         cached_page = NULL;
869         index = *ppos >> PAGE_CACHE_SHIFT;
870         next_index = index;
871         prev_index = ra.prev_page;
872         last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
873         offset = *ppos & ~PAGE_CACHE_MASK;
874
875         isize = i_size_read(inode);
876         if (!isize)
877                 goto out;
878
879         end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
880         for (;;) {
881                 struct page *page;
882                 unsigned long nr, ret;
883
884                 /* nr is the maximum number of bytes to copy from this page */
885                 nr = PAGE_CACHE_SIZE;
886                 if (index >= end_index) {
887                         if (index > end_index)
888                                 goto out;
889                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
890                         if (nr <= offset) {
891                                 goto out;
892                         }
893                 }
894                 nr = nr - offset;
895
896                 cond_resched();
897                 if (index == next_index)
898                         next_index = page_cache_readahead(mapping, &ra, filp,
899                                         index, last_index - index);
900
901 find_page:
902                 page = find_get_page(mapping, index);
903                 if (unlikely(page == NULL)) {
904                         handle_ra_miss(mapping, &ra, index);
905                         goto no_cached_page;
906                 }
907                 if (!PageUptodate(page))
908                         goto page_not_up_to_date;
909 page_ok:
910
911                 /* If users can be writing to this page using arbitrary
912                  * virtual addresses, take care about potential aliasing
913                  * before reading the page on the kernel side.
914                  */
915                 if (mapping_writably_mapped(mapping))
916                         flush_dcache_page(page);
917
918                 /*
919                  * When (part of) the same page is read multiple times
920                  * in succession, only mark it as accessed the first time.
921                  */
922                 if (prev_index != index)
923                         mark_page_accessed(page);
924                 prev_index = index;
925
926                 /*
927                  * Ok, we have the page, and it's up-to-date, so
928                  * now we can copy it to user space...
929                  *
930                  * The actor routine returns how many bytes were actually used..
931                  * NOTE! This may not be the same as how much of a user buffer
932                  * we filled up (we may be padding etc), so we can only update
933                  * "pos" here (the actor routine has to update the user buffer
934                  * pointers and the remaining count).
935                  */
936                 ret = actor(desc, page, offset, nr);
937                 offset += ret;
938                 index += offset >> PAGE_CACHE_SHIFT;
939                 offset &= ~PAGE_CACHE_MASK;
940
941                 page_cache_release(page);
942                 if (ret == nr && desc->count)
943                         continue;
944                 goto out;
945
946 page_not_up_to_date:
947                 /* Get exclusive access to the page ... */
948                 lock_page(page);
949
950                 /* Did it get unhashed before we got the lock? */
951                 if (!page->mapping) {
952                         unlock_page(page);
953                         page_cache_release(page);
954                         continue;
955                 }
956
957                 /* Did somebody else fill it already? */
958                 if (PageUptodate(page)) {
959                         unlock_page(page);
960                         goto page_ok;
961                 }
962
963 readpage:
964                 /* Start the actual read. The read will unlock the page. */
965                 error = mapping->a_ops->readpage(filp, page);
966
967                 if (unlikely(error)) {
968                         if (error == AOP_TRUNCATED_PAGE) {
969                                 page_cache_release(page);
970                                 goto find_page;
971                         }
972                         goto readpage_error;
973                 }
974
975                 if (!PageUptodate(page)) {
976                         lock_page(page);
977                         if (!PageUptodate(page)) {
978                                 if (page->mapping == NULL) {
979                                         /*
980                                          * invalidate_inode_pages got it
981                                          */
982                                         unlock_page(page);
983                                         page_cache_release(page);
984                                         goto find_page;
985                                 }
986                                 unlock_page(page);
987                                 error = -EIO;
988                                 goto readpage_error;
989                         }
990                         unlock_page(page);
991                 }
992
993                 /*
994                  * i_size must be checked after we have done ->readpage.
995                  *
996                  * Checking i_size after the readpage allows us to calculate
997                  * the correct value for "nr", which means the zero-filled
998                  * part of the page is not copied back to userspace (unless
999                  * another truncate extends the file - this is desired though).
1000                  */
1001                 isize = i_size_read(inode);
1002                 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1003                 if (unlikely(!isize || index > end_index)) {
1004                         page_cache_release(page);
1005                         goto out;
1006                 }
1007
1008                 /* nr is the maximum number of bytes to copy from this page */
1009                 nr = PAGE_CACHE_SIZE;
1010                 if (index == end_index) {
1011                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1012                         if (nr <= offset) {
1013                                 page_cache_release(page);
1014                                 goto out;
1015                         }
1016                 }
1017                 nr = nr - offset;
1018                 goto page_ok;
1019
1020 readpage_error:
1021                 /* UHHUH! A synchronous read error occurred. Report it */
1022                 desc->error = error;
1023                 page_cache_release(page);
1024                 goto out;
1025
1026 no_cached_page:
1027                 /*
1028                  * Ok, it wasn't cached, so we need to create a new
1029                  * page..
1030                  */
1031                 if (!cached_page) {
1032                         cached_page = page_cache_alloc_cold(mapping);
1033                         if (!cached_page) {
1034                                 desc->error = -ENOMEM;
1035                                 goto out;
1036                         }
1037                 }
1038                 error = add_to_page_cache_lru(cached_page, mapping,
1039                                                 index, GFP_KERNEL);
1040                 if (error) {
1041                         if (error == -EEXIST)
1042                                 goto find_page;
1043                         desc->error = error;
1044                         goto out;
1045                 }
1046                 page = cached_page;
1047                 cached_page = NULL;
1048                 goto readpage;
1049         }
1050
1051 out:
1052         *_ra = ra;
1053
1054         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1055         if (cached_page)
1056                 page_cache_release(cached_page);
1057         if (filp)
1058                 file_accessed(filp);
1059 }
1060 EXPORT_SYMBOL(do_generic_mapping_read);
1061
1062 int file_read_actor(read_descriptor_t *desc, struct page *page,
1063                         unsigned long offset, unsigned long size)
1064 {
1065         char *kaddr;
1066         unsigned long left, count = desc->count;
1067
1068         if (size > count)
1069                 size = count;
1070
1071         /*
1072          * Faults on the destination of a read are common, so do it before
1073          * taking the kmap.
1074          */
1075         if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1076                 kaddr = kmap_atomic(page, KM_USER0);
1077                 left = __copy_to_user_inatomic(desc->arg.buf,
1078                                                 kaddr + offset, size);
1079                 kunmap_atomic(kaddr, KM_USER0);
1080                 if (left == 0)
1081                         goto success;
1082         }
1083
1084         /* Do it the slow way */
1085         kaddr = kmap(page);
1086         left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1087         kunmap(page);
1088
1089         if (left) {
1090                 size -= left;
1091                 desc->error = -EFAULT;
1092         }
1093 success:
1094         desc->count = count - size;
1095         desc->written += size;
1096         desc->arg.buf += size;
1097         return size;
1098 }
1099
1100 /**
1101  * __generic_file_aio_read - generic filesystem read routine
1102  * @iocb:       kernel I/O control block
1103  * @iov:        io vector request
1104  * @nr_segs:    number of segments in the iovec
1105  * @ppos:       current file position
1106  *
1107  * This is the "read()" routine for all filesystems
1108  * that can use the page cache directly.
1109  */
1110 ssize_t
1111 __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1112                 unsigned long nr_segs, loff_t *ppos)
1113 {
1114         struct file *filp = iocb->ki_filp;
1115         ssize_t retval;
1116         unsigned long seg;
1117         size_t count;
1118
1119         count = 0;
1120         for (seg = 0; seg < nr_segs; seg++) {
1121                 const struct iovec *iv = &iov[seg];
1122
1123                 /*
1124                  * If any segment has a negative length, or the cumulative
1125                  * length ever wraps negative then return -EINVAL.
1126                  */
1127                 count += iv->iov_len;
1128                 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1129                         return -EINVAL;
1130                 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1131                         continue;
1132                 if (seg == 0)
1133                         return -EFAULT;
1134                 nr_segs = seg;
1135                 count -= iv->iov_len;   /* This segment is no good */
1136                 break;
1137         }
1138
1139         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1140         if (filp->f_flags & O_DIRECT) {
1141                 loff_t pos = *ppos, size;
1142                 struct address_space *mapping;
1143                 struct inode *inode;
1144
1145                 mapping = filp->f_mapping;
1146                 inode = mapping->host;
1147                 retval = 0;
1148                 if (!count)
1149                         goto out; /* skip atime */
1150                 size = i_size_read(inode);
1151                 if (pos < size) {
1152                         retval = generic_file_direct_IO(READ, iocb,
1153                                                 iov, pos, nr_segs);
1154                         if (retval > 0 && !is_sync_kiocb(iocb))
1155                                 retval = -EIOCBQUEUED;
1156                         if (retval > 0)
1157                                 *ppos = pos + retval;
1158                 }
1159                 file_accessed(filp);
1160                 goto out;
1161         }
1162
1163         retval = 0;
1164         if (count) {
1165                 for (seg = 0; seg < nr_segs; seg++) {
1166                         read_descriptor_t desc;
1167
1168                         desc.written = 0;
1169                         desc.arg.buf = iov[seg].iov_base;
1170                         desc.count = iov[seg].iov_len;
1171                         if (desc.count == 0)
1172                                 continue;
1173                         desc.error = 0;
1174                         do_generic_file_read(filp,ppos,&desc,file_read_actor);
1175                         retval += desc.written;
1176                         if (desc.error) {
1177                                 retval = retval ?: desc.error;
1178                                 break;
1179                         }
1180                 }
1181         }
1182 out:
1183         return retval;
1184 }
1185 EXPORT_SYMBOL(__generic_file_aio_read);
1186
1187 ssize_t
1188 generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1189 {
1190         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1191
1192         BUG_ON(iocb->ki_pos != pos);
1193         return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1194 }
1195 EXPORT_SYMBOL(generic_file_aio_read);
1196
1197 ssize_t
1198 generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1199 {
1200         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1201         struct kiocb kiocb;
1202         ssize_t ret;
1203
1204         init_sync_kiocb(&kiocb, filp);
1205         ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1206         if (-EIOCBQUEUED == ret)
1207                 ret = wait_on_sync_kiocb(&kiocb);
1208         return ret;
1209 }
1210 EXPORT_SYMBOL(generic_file_read);
1211
1212 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1213 {
1214         ssize_t written;
1215         unsigned long count = desc->count;
1216         struct file *file = desc->arg.data;
1217
1218         if (size > count)
1219                 size = count;
1220
1221         written = file->f_op->sendpage(file, page, offset,
1222                                        size, &file->f_pos, size<count);
1223         if (written < 0) {
1224                 desc->error = written;
1225                 written = 0;
1226         }
1227         desc->count = count - written;
1228         desc->written += written;
1229         return written;
1230 }
1231
1232 ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1233                          size_t count, read_actor_t actor, void *target)
1234 {
1235         read_descriptor_t desc;
1236
1237         if (!count)
1238                 return 0;
1239
1240         desc.written = 0;
1241         desc.count = count;
1242         desc.arg.data = target;
1243         desc.error = 0;
1244
1245         do_generic_file_read(in_file, ppos, &desc, actor);
1246         if (desc.written)
1247                 return desc.written;
1248         return desc.error;
1249 }
1250 EXPORT_SYMBOL(generic_file_sendfile);
1251
1252 static ssize_t
1253 do_readahead(struct address_space *mapping, struct file *filp,
1254              unsigned long index, unsigned long nr)
1255 {
1256         if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1257                 return -EINVAL;
1258
1259         force_page_cache_readahead(mapping, filp, index,
1260                                         max_sane_readahead(nr));
1261         return 0;
1262 }
1263
1264 asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1265 {
1266         ssize_t ret;
1267         struct file *file;
1268
1269         ret = -EBADF;
1270         file = fget(fd);
1271         if (file) {
1272                 if (file->f_mode & FMODE_READ) {
1273                         struct address_space *mapping = file->f_mapping;
1274                         unsigned long start = offset >> PAGE_CACHE_SHIFT;
1275                         unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1276                         unsigned long len = end - start + 1;
1277                         ret = do_readahead(mapping, file, start, len);
1278                 }
1279                 fput(file);
1280         }
1281         return ret;
1282 }
1283
1284 #ifdef CONFIG_MMU
1285 static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1286 /**
1287  * page_cache_read - adds requested page to the page cache if not already there
1288  * @file:       file to read
1289  * @offset:     page index
1290  *
1291  * This adds the requested page to the page cache if it isn't already there,
1292  * and schedules an I/O to read in its contents from disk.
1293  */
1294 static int fastcall page_cache_read(struct file * file, unsigned long offset)
1295 {
1296         struct address_space *mapping = file->f_mapping;
1297         struct page *page; 
1298         int ret;
1299
1300         do {
1301                 page = page_cache_alloc_cold(mapping);
1302                 if (!page)
1303                         return -ENOMEM;
1304
1305                 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1306                 if (ret == 0)
1307                         ret = mapping->a_ops->readpage(file, page);
1308                 else if (ret == -EEXIST)
1309                         ret = 0; /* losing race to add is OK */
1310
1311                 page_cache_release(page);
1312
1313         } while (ret == AOP_TRUNCATED_PAGE);
1314                 
1315         return ret;
1316 }
1317
1318 #define MMAP_LOTSAMISS  (100)
1319
1320 /**
1321  * filemap_nopage - read in file data for page fault handling
1322  * @area:       the applicable vm_area
1323  * @address:    target address to read in
1324  * @type:       returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1325  *
1326  * filemap_nopage() is invoked via the vma operations vector for a
1327  * mapped memory region to read in file data during a page fault.
1328  *
1329  * The goto's are kind of ugly, but this streamlines the normal case of having
1330  * it in the page cache, and handles the special cases reasonably without
1331  * having a lot of duplicated code.
1332  */
1333 struct page *filemap_nopage(struct vm_area_struct *area,
1334                                 unsigned long address, int *type)
1335 {
1336         int error;
1337         struct file *file = area->vm_file;
1338         struct address_space *mapping = file->f_mapping;
1339         struct file_ra_state *ra = &file->f_ra;
1340         struct inode *inode = mapping->host;
1341         struct page *page;
1342         unsigned long size, pgoff;
1343         int did_readaround = 0, majmin = VM_FAULT_MINOR;
1344
1345         pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1346
1347 retry_all:
1348         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1349         if (pgoff >= size)
1350                 goto outside_data_content;
1351
1352         /* If we don't want any read-ahead, don't bother */
1353         if (VM_RandomReadHint(area))
1354                 goto no_cached_page;
1355
1356         /*
1357          * The readahead code wants to be told about each and every page
1358          * so it can build and shrink its windows appropriately
1359          *
1360          * For sequential accesses, we use the generic readahead logic.
1361          */
1362         if (VM_SequentialReadHint(area))
1363                 page_cache_readahead(mapping, ra, file, pgoff, 1);
1364
1365         /*
1366          * Do we have something in the page cache already?
1367          */
1368 retry_find:
1369         page = find_get_page(mapping, pgoff);
1370         if (!page) {
1371                 unsigned long ra_pages;
1372
1373                 if (VM_SequentialReadHint(area)) {
1374                         handle_ra_miss(mapping, ra, pgoff);
1375                         goto no_cached_page;
1376                 }
1377                 ra->mmap_miss++;
1378
1379                 /*
1380                  * Do we miss much more than hit in this file? If so,
1381                  * stop bothering with read-ahead. It will only hurt.
1382                  */
1383                 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1384                         goto no_cached_page;
1385
1386                 /*
1387                  * To keep the pgmajfault counter straight, we need to
1388                  * check did_readaround, as this is an inner loop.
1389                  */
1390                 if (!did_readaround) {
1391                         majmin = VM_FAULT_MAJOR;
1392                         inc_page_state(pgmajfault);
1393                 }
1394                 did_readaround = 1;
1395                 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1396                 if (ra_pages) {
1397                         pgoff_t start = 0;
1398
1399                         if (pgoff > ra_pages / 2)
1400                                 start = pgoff - ra_pages / 2;
1401                         do_page_cache_readahead(mapping, file, start, ra_pages);
1402                 }
1403                 page = find_get_page(mapping, pgoff);
1404                 if (!page)
1405                         goto no_cached_page;
1406         }
1407
1408         if (!did_readaround)
1409                 ra->mmap_hit++;
1410
1411         /*
1412          * Ok, found a page in the page cache, now we need to check
1413          * that it's up-to-date.
1414          */
1415         if (!PageUptodate(page))
1416                 goto page_not_uptodate;
1417
1418 success:
1419         /*
1420          * Found the page and have a reference on it.
1421          */
1422         mark_page_accessed(page);
1423         if (type)
1424                 *type = majmin;
1425         return page;
1426
1427 outside_data_content:
1428         /*
1429          * An external ptracer can access pages that normally aren't
1430          * accessible..
1431          */
1432         if (area->vm_mm == current->mm)
1433                 return NULL;
1434         /* Fall through to the non-read-ahead case */
1435 no_cached_page:
1436         /*
1437          * We're only likely to ever get here if MADV_RANDOM is in
1438          * effect.
1439          */
1440         error = page_cache_read(file, pgoff);
1441         grab_swap_token();
1442
1443         /*
1444          * The page we want has now been added to the page cache.
1445          * In the unlikely event that someone removed it in the
1446          * meantime, we'll just come back here and read it again.
1447          */
1448         if (error >= 0)
1449                 goto retry_find;
1450
1451         /*
1452          * An error return from page_cache_read can result if the
1453          * system is low on memory, or a problem occurs while trying
1454          * to schedule I/O.
1455          */
1456         if (error == -ENOMEM)
1457                 return NOPAGE_OOM;
1458         return NULL;
1459
1460 page_not_uptodate:
1461         if (!did_readaround) {
1462                 majmin = VM_FAULT_MAJOR;
1463                 inc_page_state(pgmajfault);
1464         }
1465         lock_page(page);
1466
1467         /* Did it get unhashed while we waited for it? */
1468         if (!page->mapping) {
1469                 unlock_page(page);
1470                 page_cache_release(page);
1471                 goto retry_all;
1472         }
1473
1474         /* Did somebody else get it up-to-date? */
1475         if (PageUptodate(page)) {
1476                 unlock_page(page);
1477                 goto success;
1478         }
1479
1480         error = mapping->a_ops->readpage(file, page);
1481         if (!error) {
1482                 wait_on_page_locked(page);
1483                 if (PageUptodate(page))
1484                         goto success;
1485         } else if (error == AOP_TRUNCATED_PAGE) {
1486                 page_cache_release(page);
1487                 goto retry_find;
1488         }
1489
1490         /*
1491          * Umm, take care of errors if the page isn't up-to-date.
1492          * Try to re-read it _once_. We do this synchronously,
1493          * because there really aren't any performance issues here
1494          * and we need to check for errors.
1495          */
1496         lock_page(page);
1497
1498         /* Somebody truncated the page on us? */
1499         if (!page->mapping) {
1500                 unlock_page(page);
1501                 page_cache_release(page);
1502                 goto retry_all;
1503         }
1504
1505         /* Somebody else successfully read it in? */
1506         if (PageUptodate(page)) {
1507                 unlock_page(page);
1508                 goto success;
1509         }
1510         ClearPageError(page);
1511         error = mapping->a_ops->readpage(file, page);
1512         if (!error) {
1513                 wait_on_page_locked(page);
1514                 if (PageUptodate(page))
1515                         goto success;
1516         } else if (error == AOP_TRUNCATED_PAGE) {
1517                 page_cache_release(page);
1518                 goto retry_find;
1519         }
1520
1521         /*
1522          * Things didn't work out. Return zero to tell the
1523          * mm layer so, possibly freeing the page cache page first.
1524          */
1525         page_cache_release(page);
1526         return NULL;
1527 }
1528 EXPORT_SYMBOL(filemap_nopage);
1529
1530 static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1531                                         int nonblock)
1532 {
1533         struct address_space *mapping = file->f_mapping;
1534         struct page *page;
1535         int error;
1536
1537         /*
1538          * Do we have something in the page cache already?
1539          */
1540 retry_find:
1541         page = find_get_page(mapping, pgoff);
1542         if (!page) {
1543                 if (nonblock)
1544                         return NULL;
1545                 goto no_cached_page;
1546         }
1547
1548         /*
1549          * Ok, found a page in the page cache, now we need to check
1550          * that it's up-to-date.
1551          */
1552         if (!PageUptodate(page)) {
1553                 if (nonblock) {
1554                         page_cache_release(page);
1555                         return NULL;
1556                 }
1557                 goto page_not_uptodate;
1558         }
1559
1560 success:
1561         /*
1562          * Found the page and have a reference on it.
1563          */
1564         mark_page_accessed(page);
1565         return page;
1566
1567 no_cached_page:
1568         error = page_cache_read(file, pgoff);
1569
1570         /*
1571          * The page we want has now been added to the page cache.
1572          * In the unlikely event that someone removed it in the
1573          * meantime, we'll just come back here and read it again.
1574          */
1575         if (error >= 0)
1576                 goto retry_find;
1577
1578         /*
1579          * An error return from page_cache_read can result if the
1580          * system is low on memory, or a problem occurs while trying
1581          * to schedule I/O.
1582          */
1583         return NULL;
1584
1585 page_not_uptodate:
1586         lock_page(page);
1587
1588         /* Did it get unhashed while we waited for it? */
1589         if (!page->mapping) {
1590                 unlock_page(page);
1591                 goto err;
1592         }
1593
1594         /* Did somebody else get it up-to-date? */
1595         if (PageUptodate(page)) {
1596                 unlock_page(page);
1597                 goto success;
1598         }
1599
1600         error = mapping->a_ops->readpage(file, page);
1601         if (!error) {
1602                 wait_on_page_locked(page);
1603                 if (PageUptodate(page))
1604                         goto success;
1605         } else if (error == AOP_TRUNCATED_PAGE) {
1606                 page_cache_release(page);
1607                 goto retry_find;
1608         }
1609
1610         /*
1611          * Umm, take care of errors if the page isn't up-to-date.
1612          * Try to re-read it _once_. We do this synchronously,
1613          * because there really aren't any performance issues here
1614          * and we need to check for errors.
1615          */
1616         lock_page(page);
1617
1618         /* Somebody truncated the page on us? */
1619         if (!page->mapping) {
1620                 unlock_page(page);
1621                 goto err;
1622         }
1623         /* Somebody else successfully read it in? */
1624         if (PageUptodate(page)) {
1625                 unlock_page(page);
1626                 goto success;
1627         }
1628
1629         ClearPageError(page);
1630         error = mapping->a_ops->readpage(file, page);
1631         if (!error) {
1632                 wait_on_page_locked(page);
1633                 if (PageUptodate(page))
1634                         goto success;
1635         } else if (error == AOP_TRUNCATED_PAGE) {
1636                 page_cache_release(page);
1637                 goto retry_find;
1638         }
1639
1640         /*
1641          * Things didn't work out. Return zero to tell the
1642          * mm layer so, possibly freeing the page cache page first.
1643          */
1644 err:
1645         page_cache_release(page);
1646
1647         return NULL;
1648 }
1649
1650 int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1651                 unsigned long len, pgprot_t prot, unsigned long pgoff,
1652                 int nonblock)
1653 {
1654         struct file *file = vma->vm_file;
1655         struct address_space *mapping = file->f_mapping;
1656         struct inode *inode = mapping->host;
1657         unsigned long size;
1658         struct mm_struct *mm = vma->vm_mm;
1659         struct page *page;
1660         int err;
1661
1662         if (!nonblock)
1663                 force_page_cache_readahead(mapping, vma->vm_file,
1664                                         pgoff, len >> PAGE_CACHE_SHIFT);
1665
1666 repeat:
1667         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1668         if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1669                 return -EINVAL;
1670
1671         page = filemap_getpage(file, pgoff, nonblock);
1672
1673         /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1674          * done in shmem_populate calling shmem_getpage */
1675         if (!page && !nonblock)
1676                 return -ENOMEM;
1677
1678         if (page) {
1679                 err = install_page(mm, vma, addr, page, prot);
1680                 if (err) {
1681                         page_cache_release(page);
1682                         return err;
1683                 }
1684         } else if (vma->vm_flags & VM_NONLINEAR) {
1685                 /* No page was found just because we can't read it in now (being
1686                  * here implies nonblock != 0), but the page may exist, so set
1687                  * the PTE to fault it in later. */
1688                 err = install_file_pte(mm, vma, addr, pgoff, prot);
1689                 if (err)
1690                         return err;
1691         }
1692
1693         len -= PAGE_SIZE;
1694         addr += PAGE_SIZE;
1695         pgoff++;
1696         if (len)
1697                 goto repeat;
1698
1699         return 0;
1700 }
1701 EXPORT_SYMBOL(filemap_populate);
1702
1703 struct vm_operations_struct generic_file_vm_ops = {
1704         .nopage         = filemap_nopage,
1705         .populate       = filemap_populate,
1706 };
1707
1708 /* This is used for a general mmap of a disk file */
1709
1710 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1711 {
1712         struct address_space *mapping = file->f_mapping;
1713
1714         if (!mapping->a_ops->readpage)
1715                 return -ENOEXEC;
1716         file_accessed(file);
1717         vma->vm_ops = &generic_file_vm_ops;
1718         return 0;
1719 }
1720
1721 /*
1722  * This is for filesystems which do not implement ->writepage.
1723  */
1724 int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1725 {
1726         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1727                 return -EINVAL;
1728         return generic_file_mmap(file, vma);
1729 }
1730 #else
1731 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1732 {
1733         return -ENOSYS;
1734 }
1735 int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1736 {
1737         return -ENOSYS;
1738 }
1739 #endif /* CONFIG_MMU */
1740
1741 EXPORT_SYMBOL(generic_file_mmap);
1742 EXPORT_SYMBOL(generic_file_readonly_mmap);
1743
1744 static inline struct page *__read_cache_page(struct address_space *mapping,
1745                                 unsigned long index,
1746                                 int (*filler)(void *,struct page*),
1747                                 void *data)
1748 {
1749         struct page *page, *cached_page = NULL;
1750         int err;
1751 repeat:
1752         page = find_get_page(mapping, index);
1753         if (!page) {
1754                 if (!cached_page) {
1755                         cached_page = page_cache_alloc_cold(mapping);
1756                         if (!cached_page)
1757                                 return ERR_PTR(-ENOMEM);
1758                 }
1759                 err = add_to_page_cache_lru(cached_page, mapping,
1760                                         index, GFP_KERNEL);
1761                 if (err == -EEXIST)
1762                         goto repeat;
1763                 if (err < 0) {
1764                         /* Presumably ENOMEM for radix tree node */
1765                         page_cache_release(cached_page);
1766                         return ERR_PTR(err);
1767                 }
1768                 page = cached_page;
1769                 cached_page = NULL;
1770                 err = filler(data, page);
1771                 if (err < 0) {
1772                         page_cache_release(page);
1773                         page = ERR_PTR(err);
1774                 }
1775         }
1776         if (cached_page)
1777                 page_cache_release(cached_page);
1778         return page;
1779 }
1780
1781 /**
1782  * read_cache_page - read into page cache, fill it if needed
1783  * @mapping:    the page's address_space
1784  * @index:      the page index
1785  * @filler:     function to perform the read
1786  * @data:       destination for read data
1787  *
1788  * Read into the page cache. If a page already exists,
1789  * and PageUptodate() is not set, try to fill the page.
1790  */
1791 struct page *read_cache_page(struct address_space *mapping,
1792                                 unsigned long index,
1793                                 int (*filler)(void *,struct page*),
1794                                 void *data)
1795 {
1796         struct page *page;
1797         int err;
1798
1799 retry:
1800         page = __read_cache_page(mapping, index, filler, data);
1801         if (IS_ERR(page))
1802                 goto out;
1803         mark_page_accessed(page);
1804         if (PageUptodate(page))
1805                 goto out;
1806
1807         lock_page(page);
1808         if (!page->mapping) {
1809                 unlock_page(page);
1810                 page_cache_release(page);
1811                 goto retry;
1812         }
1813         if (PageUptodate(page)) {
1814                 unlock_page(page);
1815                 goto out;
1816         }
1817         err = filler(data, page);
1818         if (err < 0) {
1819                 page_cache_release(page);
1820                 page = ERR_PTR(err);
1821         }
1822  out:
1823         return page;
1824 }
1825 EXPORT_SYMBOL(read_cache_page);
1826
1827 /*
1828  * If the page was newly created, increment its refcount and add it to the
1829  * caller's lru-buffering pagevec.  This function is specifically for
1830  * generic_file_write().
1831  */
1832 static inline struct page *
1833 __grab_cache_page(struct address_space *mapping, unsigned long index,
1834                         struct page **cached_page, struct pagevec *lru_pvec)
1835 {
1836         int err;
1837         struct page *page;
1838 repeat:
1839         page = find_lock_page(mapping, index);
1840         if (!page) {
1841                 if (!*cached_page) {
1842                         *cached_page = page_cache_alloc(mapping);
1843                         if (!*cached_page)
1844                                 return NULL;
1845                 }
1846                 err = add_to_page_cache(*cached_page, mapping,
1847                                         index, GFP_KERNEL);
1848                 if (err == -EEXIST)
1849                         goto repeat;
1850                 if (err == 0) {
1851                         page = *cached_page;
1852                         page_cache_get(page);
1853                         if (!pagevec_add(lru_pvec, page))
1854                                 __pagevec_lru_add(lru_pvec);
1855                         *cached_page = NULL;
1856                 }
1857         }
1858         return page;
1859 }
1860
1861 /*
1862  * The logic we want is
1863  *
1864  *      if suid or (sgid and xgrp)
1865  *              remove privs
1866  */
1867 int remove_suid(struct dentry *dentry)
1868 {
1869         mode_t mode = dentry->d_inode->i_mode;
1870         int kill = 0;
1871         int result = 0;
1872
1873         /* suid always must be killed */
1874         if (unlikely(mode & S_ISUID))
1875                 kill = ATTR_KILL_SUID;
1876
1877         /*
1878          * sgid without any exec bits is just a mandatory locking mark; leave
1879          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1880          */
1881         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1882                 kill |= ATTR_KILL_SGID;
1883
1884         if (unlikely(kill && !capable(CAP_FSETID))) {
1885                 struct iattr newattrs;
1886
1887                 newattrs.ia_valid = ATTR_FORCE | kill;
1888                 result = notify_change(dentry, &newattrs);
1889         }
1890         return result;
1891 }
1892 EXPORT_SYMBOL(remove_suid);
1893
1894 size_t
1895 __filemap_copy_from_user_iovec_inatomic(char *vaddr,
1896                         const struct iovec *iov, size_t base, size_t bytes)
1897 {
1898         size_t copied = 0, left = 0;
1899
1900         while (bytes) {
1901                 char __user *buf = iov->iov_base + base;
1902                 int copy = min(bytes, iov->iov_len - base);
1903
1904                 base = 0;
1905                 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
1906                 copied += copy;
1907                 bytes -= copy;
1908                 vaddr += copy;
1909                 iov++;
1910
1911                 if (unlikely(left))
1912                         break;
1913         }
1914         return copied - left;
1915 }
1916
1917 /*
1918  * Performs necessary checks before doing a write
1919  *
1920  * Can adjust writing position or amount of bytes to write.
1921  * Returns appropriate error code that caller should return or
1922  * zero in case that write should be allowed.
1923  */
1924 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1925 {
1926         struct inode *inode = file->f_mapping->host;
1927         unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1928
1929         if (unlikely(*pos < 0))
1930                 return -EINVAL;
1931
1932         if (!isblk) {
1933                 /* FIXME: this is for backwards compatibility with 2.4 */
1934                 if (file->f_flags & O_APPEND)
1935                         *pos = i_size_read(inode);
1936
1937                 if (limit != RLIM_INFINITY) {
1938                         if (*pos >= limit) {
1939                                 send_sig(SIGXFSZ, current, 0);
1940                                 return -EFBIG;
1941                         }
1942                         if (*count > limit - (typeof(limit))*pos) {
1943                                 *count = limit - (typeof(limit))*pos;
1944                         }
1945                 }
1946         }
1947
1948         /*
1949          * LFS rule
1950          */
1951         if (unlikely(*pos + *count > MAX_NON_LFS &&
1952                                 !(file->f_flags & O_LARGEFILE))) {
1953                 if (*pos >= MAX_NON_LFS) {
1954                         send_sig(SIGXFSZ, current, 0);
1955                         return -EFBIG;
1956                 }
1957                 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1958                         *count = MAX_NON_LFS - (unsigned long)*pos;
1959                 }
1960         }
1961
1962         /*
1963          * Are we about to exceed the fs block limit ?
1964          *
1965          * If we have written data it becomes a short write.  If we have
1966          * exceeded without writing data we send a signal and return EFBIG.
1967          * Linus frestrict idea will clean these up nicely..
1968          */
1969         if (likely(!isblk)) {
1970                 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1971                         if (*count || *pos > inode->i_sb->s_maxbytes) {
1972                                 send_sig(SIGXFSZ, current, 0);
1973                                 return -EFBIG;
1974                         }
1975                         /* zero-length writes at ->s_maxbytes are OK */
1976                 }
1977
1978                 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1979                         *count = inode->i_sb->s_maxbytes - *pos;
1980         } else {
1981                 loff_t isize;
1982                 if (bdev_read_only(I_BDEV(inode)))
1983                         return -EPERM;
1984                 isize = i_size_read(inode);
1985                 if (*pos >= isize) {
1986                         if (*count || *pos > isize)
1987                                 return -ENOSPC;
1988                 }
1989
1990                 if (*pos + *count > isize)
1991                         *count = isize - *pos;
1992         }
1993         return 0;
1994 }
1995 EXPORT_SYMBOL(generic_write_checks);
1996
1997 ssize_t
1998 generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1999                 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2000                 size_t count, size_t ocount)
2001 {
2002         struct file     *file = iocb->ki_filp;
2003         struct address_space *mapping = file->f_mapping;
2004         struct inode    *inode = mapping->host;
2005         ssize_t         written;
2006
2007         if (count != ocount)
2008                 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2009
2010         written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2011         if (written > 0) {
2012                 loff_t end = pos + written;
2013                 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2014                         i_size_write(inode,  end);
2015                         mark_inode_dirty(inode);
2016                 }
2017                 *ppos = end;
2018         }
2019
2020         /*
2021          * Sync the fs metadata but not the minor inode changes and
2022          * of course not the data as we did direct DMA for the IO.
2023          * i_mutex is held, which protects generic_osync_inode() from
2024          * livelocking.
2025          */
2026         if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2027                 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2028                 if (err < 0)
2029                         written = err;
2030         }
2031         if (written == count && !is_sync_kiocb(iocb))
2032                 written = -EIOCBQUEUED;
2033         return written;
2034 }
2035 EXPORT_SYMBOL(generic_file_direct_write);
2036
2037 ssize_t
2038 generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2039                 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2040                 size_t count, ssize_t written)
2041 {
2042         struct file *file = iocb->ki_filp;
2043         struct address_space * mapping = file->f_mapping;
2044         struct address_space_operations *a_ops = mapping->a_ops;
2045         struct inode    *inode = mapping->host;
2046         long            status = 0;
2047         struct page     *page;
2048         struct page     *cached_page = NULL;
2049         size_t          bytes;
2050         struct pagevec  lru_pvec;
2051         const struct iovec *cur_iov = iov; /* current iovec */
2052         size_t          iov_base = 0;      /* offset in the current iovec */
2053         char __user     *buf;
2054
2055         pagevec_init(&lru_pvec, 0);
2056
2057         /*
2058          * handle partial DIO write.  Adjust cur_iov if needed.
2059          */
2060         if (likely(nr_segs == 1))
2061                 buf = iov->iov_base + written;
2062         else {
2063                 filemap_set_next_iovec(&cur_iov, &iov_base, written);
2064                 buf = cur_iov->iov_base + iov_base;
2065         }
2066
2067         do {
2068                 unsigned long index;
2069                 unsigned long offset;
2070                 unsigned long maxlen;
2071                 size_t copied;
2072
2073                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2074                 index = pos >> PAGE_CACHE_SHIFT;
2075                 bytes = PAGE_CACHE_SIZE - offset;
2076                 if (bytes > count)
2077                         bytes = count;
2078
2079                 /*
2080                  * Bring in the user page that we will copy from _first_.
2081                  * Otherwise there's a nasty deadlock on copying from the
2082                  * same page as we're writing to, without it being marked
2083                  * up-to-date.
2084                  */
2085                 maxlen = cur_iov->iov_len - iov_base;
2086                 if (maxlen > bytes)
2087                         maxlen = bytes;
2088                 fault_in_pages_readable(buf, maxlen);
2089
2090                 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2091                 if (!page) {
2092                         status = -ENOMEM;
2093                         break;
2094                 }
2095
2096                 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2097                 if (unlikely(status)) {
2098                         loff_t isize = i_size_read(inode);
2099
2100                         if (status != AOP_TRUNCATED_PAGE)
2101                                 unlock_page(page);
2102                         page_cache_release(page);
2103                         if (status == AOP_TRUNCATED_PAGE)
2104                                 continue;
2105                         /*
2106                          * prepare_write() may have instantiated a few blocks
2107                          * outside i_size.  Trim these off again.
2108                          */
2109                         if (pos + bytes > isize)
2110                                 vmtruncate(inode, isize);
2111                         break;
2112                 }
2113                 if (likely(nr_segs == 1))
2114                         copied = filemap_copy_from_user(page, offset,
2115                                                         buf, bytes);
2116                 else
2117                         copied = filemap_copy_from_user_iovec(page, offset,
2118                                                 cur_iov, iov_base, bytes);
2119                 flush_dcache_page(page);
2120                 status = a_ops->commit_write(file, page, offset, offset+bytes);
2121                 if (status == AOP_TRUNCATED_PAGE) {
2122                         page_cache_release(page);
2123                         continue;
2124                 }
2125                 if (likely(copied > 0)) {
2126                         if (!status)
2127                                 status = copied;
2128
2129                         if (status >= 0) {
2130                                 written += status;
2131                                 count -= status;
2132                                 pos += status;
2133                                 buf += status;
2134                                 if (unlikely(nr_segs > 1)) {
2135                                         filemap_set_next_iovec(&cur_iov,
2136                                                         &iov_base, status);
2137                                         if (count)
2138                                                 buf = cur_iov->iov_base +
2139                                                         iov_base;
2140                                 } else {
2141                                         iov_base += status;
2142                                 }
2143                         }
2144                 }
2145                 if (unlikely(copied != bytes))
2146                         if (status >= 0)
2147                                 status = -EFAULT;
2148                 unlock_page(page);
2149                 mark_page_accessed(page);
2150                 page_cache_release(page);
2151                 if (status < 0)
2152                         break;
2153                 balance_dirty_pages_ratelimited(mapping);
2154                 cond_resched();
2155         } while (count);
2156         *ppos = pos;
2157
2158         if (cached_page)
2159                 page_cache_release(cached_page);
2160
2161         /*
2162          * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2163          */
2164         if (likely(status >= 0)) {
2165                 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2166                         if (!a_ops->writepage || !is_sync_kiocb(iocb))
2167                                 status = generic_osync_inode(inode, mapping,
2168                                                 OSYNC_METADATA|OSYNC_DATA);
2169                 }
2170         }
2171         
2172         /*
2173          * If we get here for O_DIRECT writes then we must have fallen through
2174          * to buffered writes (block instantiation inside i_size).  So we sync
2175          * the file data here, to try to honour O_DIRECT expectations.
2176          */
2177         if (unlikely(file->f_flags & O_DIRECT) && written)
2178                 status = filemap_write_and_wait(mapping);
2179
2180         pagevec_lru_add(&lru_pvec);
2181         return written ? written : status;
2182 }
2183 EXPORT_SYMBOL(generic_file_buffered_write);
2184
2185 static ssize_t
2186 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2187                                 unsigned long nr_segs, loff_t *ppos)
2188 {
2189         struct file *file = iocb->ki_filp;
2190         struct address_space * mapping = file->f_mapping;
2191         size_t ocount;          /* original count */
2192         size_t count;           /* after file limit checks */
2193         struct inode    *inode = mapping->host;
2194         unsigned long   seg;
2195         loff_t          pos;
2196         ssize_t         written;
2197         ssize_t         err;
2198
2199         ocount = 0;
2200         for (seg = 0; seg < nr_segs; seg++) {
2201                 const struct iovec *iv = &iov[seg];
2202
2203                 /*
2204                  * If any segment has a negative length, or the cumulative
2205                  * length ever wraps negative then return -EINVAL.
2206                  */
2207                 ocount += iv->iov_len;
2208                 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2209                         return -EINVAL;
2210                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2211                         continue;
2212                 if (seg == 0)
2213                         return -EFAULT;
2214                 nr_segs = seg;
2215                 ocount -= iv->iov_len;  /* This segment is no good */
2216                 break;
2217         }
2218
2219         count = ocount;
2220         pos = *ppos;
2221
2222         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2223
2224         /* We can write back this queue in page reclaim */
2225         current->backing_dev_info = mapping->backing_dev_info;
2226         written = 0;
2227
2228         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2229         if (err)
2230                 goto out;
2231
2232         if (count == 0)
2233                 goto out;
2234
2235         err = remove_suid(file->f_dentry);
2236         if (err)
2237                 goto out;
2238
2239         file_update_time(file);
2240
2241         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2242         if (unlikely(file->f_flags & O_DIRECT)) {
2243                 written = generic_file_direct_write(iocb, iov,
2244                                 &nr_segs, pos, ppos, count, ocount);
2245                 if (written < 0 || written == count)
2246                         goto out;
2247                 /*
2248                  * direct-io write to a hole: fall through to buffered I/O
2249                  * for completing the rest of the request.
2250                  */
2251                 pos += written;
2252                 count -= written;
2253         }
2254
2255         written = generic_file_buffered_write(iocb, iov, nr_segs,
2256                         pos, ppos, count, written);
2257 out:
2258         current->backing_dev_info = NULL;
2259         return written ? written : err;
2260 }
2261 EXPORT_SYMBOL(generic_file_aio_write_nolock);
2262
2263 ssize_t
2264 generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2265                                 unsigned long nr_segs, loff_t *ppos)
2266 {
2267         struct file *file = iocb->ki_filp;
2268         struct address_space *mapping = file->f_mapping;
2269         struct inode *inode = mapping->host;
2270         ssize_t ret;
2271         loff_t pos = *ppos;
2272
2273         ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2274
2275         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2276                 int err;
2277
2278                 err = sync_page_range_nolock(inode, mapping, pos, ret);
2279                 if (err < 0)
2280                         ret = err;
2281         }
2282         return ret;
2283 }
2284
2285 static ssize_t
2286 __generic_file_write_nolock(struct file *file, const struct iovec *iov,
2287                                 unsigned long nr_segs, loff_t *ppos)
2288 {
2289         struct kiocb kiocb;
2290         ssize_t ret;
2291
2292         init_sync_kiocb(&kiocb, file);
2293         ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2294         if (ret == -EIOCBQUEUED)
2295                 ret = wait_on_sync_kiocb(&kiocb);
2296         return ret;
2297 }
2298
2299 ssize_t
2300 generic_file_write_nolock(struct file *file, const struct iovec *iov,
2301                                 unsigned long nr_segs, loff_t *ppos)
2302 {
2303         struct kiocb kiocb;
2304         ssize_t ret;
2305
2306         init_sync_kiocb(&kiocb, file);
2307         ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2308         if (-EIOCBQUEUED == ret)
2309                 ret = wait_on_sync_kiocb(&kiocb);
2310         return ret;
2311 }
2312 EXPORT_SYMBOL(generic_file_write_nolock);
2313
2314 ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2315                                size_t count, loff_t pos)
2316 {
2317         struct file *file = iocb->ki_filp;
2318         struct address_space *mapping = file->f_mapping;
2319         struct inode *inode = mapping->host;
2320         ssize_t ret;
2321         struct iovec local_iov = { .iov_base = (void __user *)buf,
2322                                         .iov_len = count };
2323
2324         BUG_ON(iocb->ki_pos != pos);
2325
2326         mutex_lock(&inode->i_mutex);
2327         ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2328                                                 &iocb->ki_pos);
2329         mutex_unlock(&inode->i_mutex);
2330
2331         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2332                 ssize_t err;
2333
2334                 err = sync_page_range(inode, mapping, pos, ret);
2335                 if (err < 0)
2336                         ret = err;
2337         }
2338         return ret;
2339 }
2340 EXPORT_SYMBOL(generic_file_aio_write);
2341
2342 ssize_t generic_file_write(struct file *file, const char __user *buf,
2343                            size_t count, loff_t *ppos)
2344 {
2345         struct address_space *mapping = file->f_mapping;
2346         struct inode *inode = mapping->host;
2347         ssize_t ret;
2348         struct iovec local_iov = { .iov_base = (void __user *)buf,
2349                                         .iov_len = count };
2350
2351         mutex_lock(&inode->i_mutex);
2352         ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2353         mutex_unlock(&inode->i_mutex);
2354
2355         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2356                 ssize_t err;
2357
2358                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2359                 if (err < 0)
2360                         ret = err;
2361         }
2362         return ret;
2363 }
2364 EXPORT_SYMBOL(generic_file_write);
2365
2366 ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2367                         unsigned long nr_segs, loff_t *ppos)
2368 {
2369         struct kiocb kiocb;
2370         ssize_t ret;
2371
2372         init_sync_kiocb(&kiocb, filp);
2373         ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2374         if (-EIOCBQUEUED == ret)
2375                 ret = wait_on_sync_kiocb(&kiocb);
2376         return ret;
2377 }
2378 EXPORT_SYMBOL(generic_file_readv);
2379
2380 ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2381                         unsigned long nr_segs, loff_t *ppos)
2382 {
2383         struct address_space *mapping = file->f_mapping;
2384         struct inode *inode = mapping->host;
2385         ssize_t ret;
2386
2387         mutex_lock(&inode->i_mutex);
2388         ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2389         mutex_unlock(&inode->i_mutex);
2390
2391         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2392                 int err;
2393
2394                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2395                 if (err < 0)
2396                         ret = err;
2397         }
2398         return ret;
2399 }
2400 EXPORT_SYMBOL(generic_file_writev);
2401
2402 /*
2403  * Called under i_mutex for writes to S_ISREG files.   Returns -EIO if something
2404  * went wrong during pagecache shootdown.
2405  */
2406 static ssize_t
2407 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2408         loff_t offset, unsigned long nr_segs)
2409 {
2410         struct file *file = iocb->ki_filp;
2411         struct address_space *mapping = file->f_mapping;
2412         ssize_t retval;
2413         size_t write_len = 0;
2414
2415         /*
2416          * If it's a write, unmap all mmappings of the file up-front.  This
2417          * will cause any pte dirty bits to be propagated into the pageframes
2418          * for the subsequent filemap_write_and_wait().
2419          */
2420         if (rw == WRITE) {
2421                 write_len = iov_length(iov, nr_segs);
2422                 if (mapping_mapped(mapping))
2423                         unmap_mapping_range(mapping, offset, write_len, 0);
2424         }
2425
2426         retval = filemap_write_and_wait(mapping);
2427         if (retval == 0) {
2428                 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2429                                                 offset, nr_segs);
2430                 if (rw == WRITE && mapping->nrpages) {
2431                         pgoff_t end = (offset + write_len - 1)
2432                                                 >> PAGE_CACHE_SHIFT;
2433                         int err = invalidate_inode_pages2_range(mapping,
2434                                         offset >> PAGE_CACHE_SHIFT, end);
2435                         if (err)
2436                                 retval = err;
2437                 }
2438         }
2439         return retval;
2440 }