[PATCH] mm: migration page refcounting fix
[linux-2.6.git] / mm / filemap.c
1 /*
2  *      linux/mm/filemap.c
3  *
4  * Copyright (C) 1994-1999  Linus Torvalds
5  */
6
7 /*
8  * This file handles the generic file mmap semantics used by
9  * most "normal" filesystems (but you don't /have/ to use this:
10  * the NFS filesystem used to do this differently, for example)
11  */
12 #include <linux/config.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/compiler.h>
16 #include <linux/fs.h>
17 #include <linux/aio.h>
18 #include <linux/capability.h>
19 #include <linux/kernel_stat.h>
20 #include <linux/mm.h>
21 #include <linux/swap.h>
22 #include <linux/mman.h>
23 #include <linux/pagemap.h>
24 #include <linux/file.h>
25 #include <linux/uio.h>
26 #include <linux/hash.h>
27 #include <linux/writeback.h>
28 #include <linux/pagevec.h>
29 #include <linux/blkdev.h>
30 #include <linux/security.h>
31 #include <linux/syscalls.h>
32 #include "filemap.h"
33 /*
34  * FIXME: remove all knowledge of the buffer layer from the core VM
35  */
36 #include <linux/buffer_head.h> /* for generic_osync_inode */
37
38 #include <asm/uaccess.h>
39 #include <asm/mman.h>
40
41 static ssize_t
42 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
43         loff_t offset, unsigned long nr_segs);
44
45 /*
46  * Shared mappings implemented 30.11.1994. It's not fully working yet,
47  * though.
48  *
49  * Shared mappings now work. 15.8.1995  Bruno.
50  *
51  * finished 'unifying' the page and buffer cache and SMP-threaded the
52  * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
53  *
54  * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
55  */
56
57 /*
58  * Lock ordering:
59  *
60  *  ->i_mmap_lock               (vmtruncate)
61  *    ->private_lock            (__free_pte->__set_page_dirty_buffers)
62  *      ->swap_lock             (exclusive_swap_page, others)
63  *        ->mapping->tree_lock
64  *
65  *  ->i_mutex
66  *    ->i_mmap_lock             (truncate->unmap_mapping_range)
67  *
68  *  ->mmap_sem
69  *    ->i_mmap_lock
70  *      ->page_table_lock or pte_lock   (various, mainly in memory.c)
71  *        ->mapping->tree_lock  (arch-dependent flush_dcache_mmap_lock)
72  *
73  *  ->mmap_sem
74  *    ->lock_page               (access_process_vm)
75  *
76  *  ->mmap_sem
77  *    ->i_mutex                 (msync)
78  *
79  *  ->i_mutex
80  *    ->i_alloc_sem             (various)
81  *
82  *  ->inode_lock
83  *    ->sb_lock                 (fs/fs-writeback.c)
84  *    ->mapping->tree_lock      (__sync_single_inode)
85  *
86  *  ->i_mmap_lock
87  *    ->anon_vma.lock           (vma_adjust)
88  *
89  *  ->anon_vma.lock
90  *    ->page_table_lock or pte_lock     (anon_vma_prepare and various)
91  *
92  *  ->page_table_lock or pte_lock
93  *    ->swap_lock               (try_to_unmap_one)
94  *    ->private_lock            (try_to_unmap_one)
95  *    ->tree_lock               (try_to_unmap_one)
96  *    ->zone.lru_lock           (follow_page->mark_page_accessed)
97  *    ->zone.lru_lock           (check_pte_range->isolate_lru_page)
98  *    ->private_lock            (page_remove_rmap->set_page_dirty)
99  *    ->tree_lock               (page_remove_rmap->set_page_dirty)
100  *    ->inode_lock              (page_remove_rmap->set_page_dirty)
101  *    ->inode_lock              (zap_pte_range->set_page_dirty)
102  *    ->private_lock            (zap_pte_range->__set_page_dirty_buffers)
103  *
104  *  ->task->proc_lock
105  *    ->dcache_lock             (proc_pid_lookup)
106  */
107
108 /*
109  * Remove a page from the page cache and free it. Caller has to make
110  * sure the page is locked and that nobody else uses it - or that usage
111  * is safe.  The caller must hold a write_lock on the mapping's tree_lock.
112  */
113 void __remove_from_page_cache(struct page *page)
114 {
115         struct address_space *mapping = page->mapping;
116
117         radix_tree_delete(&mapping->page_tree, page->index);
118         page->mapping = NULL;
119         mapping->nrpages--;
120         pagecache_acct(-1);
121 }
122
123 void remove_from_page_cache(struct page *page)
124 {
125         struct address_space *mapping = page->mapping;
126
127         BUG_ON(!PageLocked(page));
128
129         write_lock_irq(&mapping->tree_lock);
130         __remove_from_page_cache(page);
131         write_unlock_irq(&mapping->tree_lock);
132 }
133
134 static int sync_page(void *word)
135 {
136         struct address_space *mapping;
137         struct page *page;
138
139         page = container_of((unsigned long *)word, struct page, flags);
140
141         /*
142          * page_mapping() is being called without PG_locked held.
143          * Some knowledge of the state and use of the page is used to
144          * reduce the requirements down to a memory barrier.
145          * The danger here is of a stale page_mapping() return value
146          * indicating a struct address_space different from the one it's
147          * associated with when it is associated with one.
148          * After smp_mb(), it's either the correct page_mapping() for
149          * the page, or an old page_mapping() and the page's own
150          * page_mapping() has gone NULL.
151          * The ->sync_page() address_space operation must tolerate
152          * page_mapping() going NULL. By an amazing coincidence,
153          * this comes about because none of the users of the page
154          * in the ->sync_page() methods make essential use of the
155          * page_mapping(), merely passing the page down to the backing
156          * device's unplug functions when it's non-NULL, which in turn
157          * ignore it for all cases but swap, where only page_private(page) is
158          * of interest. When page_mapping() does go NULL, the entire
159          * call stack gracefully ignores the page and returns.
160          * -- wli
161          */
162         smp_mb();
163         mapping = page_mapping(page);
164         if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
165                 mapping->a_ops->sync_page(page);
166         io_schedule();
167         return 0;
168 }
169
170 /**
171  * filemap_fdatawrite_range - start writeback against all of a mapping's
172  * dirty pages that lie within the byte offsets <start, end>
173  * @mapping:    address space structure to write
174  * @start:      offset in bytes where the range starts
175  * @end:        offset in bytes where the range ends
176  * @sync_mode:  enable synchronous operation
177  *
178  * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
179  * opposed to a regular memory * cleansing writeback.  The difference between
180  * these two operations is that if a dirty page/buffer is encountered, it must
181  * be waited upon, and not just skipped over.
182  */
183 static int __filemap_fdatawrite_range(struct address_space *mapping,
184         loff_t start, loff_t end, int sync_mode)
185 {
186         int ret;
187         struct writeback_control wbc = {
188                 .sync_mode = sync_mode,
189                 .nr_to_write = mapping->nrpages * 2,
190                 .start = start,
191                 .end = end,
192         };
193
194         if (!mapping_cap_writeback_dirty(mapping))
195                 return 0;
196
197         ret = do_writepages(mapping, &wbc);
198         return ret;
199 }
200
201 static inline int __filemap_fdatawrite(struct address_space *mapping,
202         int sync_mode)
203 {
204         return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
205 }
206
207 int filemap_fdatawrite(struct address_space *mapping)
208 {
209         return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
210 }
211 EXPORT_SYMBOL(filemap_fdatawrite);
212
213 static int filemap_fdatawrite_range(struct address_space *mapping,
214         loff_t start, loff_t end)
215 {
216         return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
217 }
218
219 /*
220  * This is a mostly non-blocking flush.  Not suitable for data-integrity
221  * purposes - I/O may not be started against all dirty pages.
222  */
223 int filemap_flush(struct address_space *mapping)
224 {
225         return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
226 }
227 EXPORT_SYMBOL(filemap_flush);
228
229 /*
230  * Wait for writeback to complete against pages indexed by start->end
231  * inclusive
232  */
233 static int wait_on_page_writeback_range(struct address_space *mapping,
234                                 pgoff_t start, pgoff_t end)
235 {
236         struct pagevec pvec;
237         int nr_pages;
238         int ret = 0;
239         pgoff_t index;
240
241         if (end < start)
242                 return 0;
243
244         pagevec_init(&pvec, 0);
245         index = start;
246         while ((index <= end) &&
247                         (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
248                         PAGECACHE_TAG_WRITEBACK,
249                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
250                 unsigned i;
251
252                 for (i = 0; i < nr_pages; i++) {
253                         struct page *page = pvec.pages[i];
254
255                         /* until radix tree lookup accepts end_index */
256                         if (page->index > end)
257                                 continue;
258
259                         wait_on_page_writeback(page);
260                         if (PageError(page))
261                                 ret = -EIO;
262                 }
263                 pagevec_release(&pvec);
264                 cond_resched();
265         }
266
267         /* Check for outstanding write errors */
268         if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
269                 ret = -ENOSPC;
270         if (test_and_clear_bit(AS_EIO, &mapping->flags))
271                 ret = -EIO;
272
273         return ret;
274 }
275
276 /*
277  * Write and wait upon all the pages in the passed range.  This is a "data
278  * integrity" operation.  It waits upon in-flight writeout before starting and
279  * waiting upon new writeout.  If there was an IO error, return it.
280  *
281  * We need to re-take i_mutex during the generic_osync_inode list walk because
282  * it is otherwise livelockable.
283  */
284 int sync_page_range(struct inode *inode, struct address_space *mapping,
285                         loff_t pos, loff_t count)
286 {
287         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
288         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
289         int ret;
290
291         if (!mapping_cap_writeback_dirty(mapping) || !count)
292                 return 0;
293         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
294         if (ret == 0) {
295                 mutex_lock(&inode->i_mutex);
296                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
297                 mutex_unlock(&inode->i_mutex);
298         }
299         if (ret == 0)
300                 ret = wait_on_page_writeback_range(mapping, start, end);
301         return ret;
302 }
303 EXPORT_SYMBOL(sync_page_range);
304
305 /*
306  * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
307  * as it forces O_SYNC writers to different parts of the same file
308  * to be serialised right until io completion.
309  */
310 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
311                            loff_t pos, loff_t count)
312 {
313         pgoff_t start = pos >> PAGE_CACHE_SHIFT;
314         pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
315         int ret;
316
317         if (!mapping_cap_writeback_dirty(mapping) || !count)
318                 return 0;
319         ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
320         if (ret == 0)
321                 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
322         if (ret == 0)
323                 ret = wait_on_page_writeback_range(mapping, start, end);
324         return ret;
325 }
326 EXPORT_SYMBOL(sync_page_range_nolock);
327
328 /**
329  * filemap_fdatawait - walk the list of under-writeback pages of the given
330  *     address space and wait for all of them.
331  *
332  * @mapping: address space structure to wait for
333  */
334 int filemap_fdatawait(struct address_space *mapping)
335 {
336         loff_t i_size = i_size_read(mapping->host);
337
338         if (i_size == 0)
339                 return 0;
340
341         return wait_on_page_writeback_range(mapping, 0,
342                                 (i_size - 1) >> PAGE_CACHE_SHIFT);
343 }
344 EXPORT_SYMBOL(filemap_fdatawait);
345
346 int filemap_write_and_wait(struct address_space *mapping)
347 {
348         int err = 0;
349
350         if (mapping->nrpages) {
351                 err = filemap_fdatawrite(mapping);
352                 /*
353                  * Even if the above returned error, the pages may be
354                  * written partially (e.g. -ENOSPC), so we wait for it.
355                  * But the -EIO is special case, it may indicate the worst
356                  * thing (e.g. bug) happened, so we avoid waiting for it.
357                  */
358                 if (err != -EIO) {
359                         int err2 = filemap_fdatawait(mapping);
360                         if (!err)
361                                 err = err2;
362                 }
363         }
364         return err;
365 }
366 EXPORT_SYMBOL(filemap_write_and_wait);
367
368 int filemap_write_and_wait_range(struct address_space *mapping,
369                                  loff_t lstart, loff_t lend)
370 {
371         int err = 0;
372
373         if (mapping->nrpages) {
374                 err = __filemap_fdatawrite_range(mapping, lstart, lend,
375                                                  WB_SYNC_ALL);
376                 /* See comment of filemap_write_and_wait() */
377                 if (err != -EIO) {
378                         int err2 = wait_on_page_writeback_range(mapping,
379                                                 lstart >> PAGE_CACHE_SHIFT,
380                                                 lend >> PAGE_CACHE_SHIFT);
381                         if (!err)
382                                 err = err2;
383                 }
384         }
385         return err;
386 }
387
388 /*
389  * This function is used to add newly allocated pagecache pages:
390  * the page is new, so we can just run SetPageLocked() against it.
391  * The other page state flags were set by rmqueue().
392  *
393  * This function does not add the page to the LRU.  The caller must do that.
394  */
395 int add_to_page_cache(struct page *page, struct address_space *mapping,
396                 pgoff_t offset, gfp_t gfp_mask)
397 {
398         int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
399
400         if (error == 0) {
401                 write_lock_irq(&mapping->tree_lock);
402                 error = radix_tree_insert(&mapping->page_tree, offset, page);
403                 if (!error) {
404                         page_cache_get(page);
405                         SetPageLocked(page);
406                         page->mapping = mapping;
407                         page->index = offset;
408                         mapping->nrpages++;
409                         pagecache_acct(1);
410                 }
411                 write_unlock_irq(&mapping->tree_lock);
412                 radix_tree_preload_end();
413         }
414         return error;
415 }
416
417 EXPORT_SYMBOL(add_to_page_cache);
418
419 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
420                                 pgoff_t offset, gfp_t gfp_mask)
421 {
422         int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
423         if (ret == 0)
424                 lru_cache_add(page);
425         return ret;
426 }
427
428 /*
429  * In order to wait for pages to become available there must be
430  * waitqueues associated with pages. By using a hash table of
431  * waitqueues where the bucket discipline is to maintain all
432  * waiters on the same queue and wake all when any of the pages
433  * become available, and for the woken contexts to check to be
434  * sure the appropriate page became available, this saves space
435  * at a cost of "thundering herd" phenomena during rare hash
436  * collisions.
437  */
438 static wait_queue_head_t *page_waitqueue(struct page *page)
439 {
440         const struct zone *zone = page_zone(page);
441
442         return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
443 }
444
445 static inline void wake_up_page(struct page *page, int bit)
446 {
447         __wake_up_bit(page_waitqueue(page), &page->flags, bit);
448 }
449
450 void fastcall wait_on_page_bit(struct page *page, int bit_nr)
451 {
452         DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
453
454         if (test_bit(bit_nr, &page->flags))
455                 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
456                                                         TASK_UNINTERRUPTIBLE);
457 }
458 EXPORT_SYMBOL(wait_on_page_bit);
459
460 /**
461  * unlock_page() - unlock a locked page
462  *
463  * @page: the page
464  *
465  * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
466  * Also wakes sleepers in wait_on_page_writeback() because the wakeup
467  * mechananism between PageLocked pages and PageWriteback pages is shared.
468  * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
469  *
470  * The first mb is necessary to safely close the critical section opened by the
471  * TestSetPageLocked(), the second mb is necessary to enforce ordering between
472  * the clear_bit and the read of the waitqueue (to avoid SMP races with a
473  * parallel wait_on_page_locked()).
474  */
475 void fastcall unlock_page(struct page *page)
476 {
477         smp_mb__before_clear_bit();
478         if (!TestClearPageLocked(page))
479                 BUG();
480         smp_mb__after_clear_bit(); 
481         wake_up_page(page, PG_locked);
482 }
483 EXPORT_SYMBOL(unlock_page);
484
485 /*
486  * End writeback against a page.
487  */
488 void end_page_writeback(struct page *page)
489 {
490         if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
491                 if (!test_clear_page_writeback(page))
492                         BUG();
493         }
494         smp_mb__after_clear_bit();
495         wake_up_page(page, PG_writeback);
496 }
497 EXPORT_SYMBOL(end_page_writeback);
498
499 /*
500  * Get a lock on the page, assuming we need to sleep to get it.
501  *
502  * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary.  If some
503  * random driver's requestfn sets TASK_RUNNING, we could busywait.  However
504  * chances are that on the second loop, the block layer's plug list is empty,
505  * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
506  */
507 void fastcall __lock_page(struct page *page)
508 {
509         DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
510
511         __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
512                                                         TASK_UNINTERRUPTIBLE);
513 }
514 EXPORT_SYMBOL(__lock_page);
515
516 /*
517  * a rather lightweight function, finding and getting a reference to a
518  * hashed page atomically.
519  */
520 struct page * find_get_page(struct address_space *mapping, unsigned long offset)
521 {
522         struct page *page;
523
524         read_lock_irq(&mapping->tree_lock);
525         page = radix_tree_lookup(&mapping->page_tree, offset);
526         if (page)
527                 page_cache_get(page);
528         read_unlock_irq(&mapping->tree_lock);
529         return page;
530 }
531
532 EXPORT_SYMBOL(find_get_page);
533
534 /*
535  * Same as above, but trylock it instead of incrementing the count.
536  */
537 struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
538 {
539         struct page *page;
540
541         read_lock_irq(&mapping->tree_lock);
542         page = radix_tree_lookup(&mapping->page_tree, offset);
543         if (page && TestSetPageLocked(page))
544                 page = NULL;
545         read_unlock_irq(&mapping->tree_lock);
546         return page;
547 }
548
549 EXPORT_SYMBOL(find_trylock_page);
550
551 /**
552  * find_lock_page - locate, pin and lock a pagecache page
553  *
554  * @mapping: the address_space to search
555  * @offset: the page index
556  *
557  * Locates the desired pagecache page, locks it, increments its reference
558  * count and returns its address.
559  *
560  * Returns zero if the page was not present. find_lock_page() may sleep.
561  */
562 struct page *find_lock_page(struct address_space *mapping,
563                                 unsigned long offset)
564 {
565         struct page *page;
566
567         read_lock_irq(&mapping->tree_lock);
568 repeat:
569         page = radix_tree_lookup(&mapping->page_tree, offset);
570         if (page) {
571                 page_cache_get(page);
572                 if (TestSetPageLocked(page)) {
573                         read_unlock_irq(&mapping->tree_lock);
574                         __lock_page(page);
575                         read_lock_irq(&mapping->tree_lock);
576
577                         /* Has the page been truncated while we slept? */
578                         if (unlikely(page->mapping != mapping ||
579                                      page->index != offset)) {
580                                 unlock_page(page);
581                                 page_cache_release(page);
582                                 goto repeat;
583                         }
584                 }
585         }
586         read_unlock_irq(&mapping->tree_lock);
587         return page;
588 }
589
590 EXPORT_SYMBOL(find_lock_page);
591
592 /**
593  * find_or_create_page - locate or add a pagecache page
594  *
595  * @mapping: the page's address_space
596  * @index: the page's index into the mapping
597  * @gfp_mask: page allocation mode
598  *
599  * Locates a page in the pagecache.  If the page is not present, a new page
600  * is allocated using @gfp_mask and is added to the pagecache and to the VM's
601  * LRU list.  The returned page is locked and has its reference count
602  * incremented.
603  *
604  * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
605  * allocation!
606  *
607  * find_or_create_page() returns the desired page's address, or zero on
608  * memory exhaustion.
609  */
610 struct page *find_or_create_page(struct address_space *mapping,
611                 unsigned long index, gfp_t gfp_mask)
612 {
613         struct page *page, *cached_page = NULL;
614         int err;
615 repeat:
616         page = find_lock_page(mapping, index);
617         if (!page) {
618                 if (!cached_page) {
619                         cached_page = alloc_page(gfp_mask);
620                         if (!cached_page)
621                                 return NULL;
622                 }
623                 err = add_to_page_cache_lru(cached_page, mapping,
624                                         index, gfp_mask);
625                 if (!err) {
626                         page = cached_page;
627                         cached_page = NULL;
628                 } else if (err == -EEXIST)
629                         goto repeat;
630         }
631         if (cached_page)
632                 page_cache_release(cached_page);
633         return page;
634 }
635
636 EXPORT_SYMBOL(find_or_create_page);
637
638 /**
639  * find_get_pages - gang pagecache lookup
640  * @mapping:    The address_space to search
641  * @start:      The starting page index
642  * @nr_pages:   The maximum number of pages
643  * @pages:      Where the resulting pages are placed
644  *
645  * find_get_pages() will search for and return a group of up to
646  * @nr_pages pages in the mapping.  The pages are placed at @pages.
647  * find_get_pages() takes a reference against the returned pages.
648  *
649  * The search returns a group of mapping-contiguous pages with ascending
650  * indexes.  There may be holes in the indices due to not-present pages.
651  *
652  * find_get_pages() returns the number of pages which were found.
653  */
654 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
655                             unsigned int nr_pages, struct page **pages)
656 {
657         unsigned int i;
658         unsigned int ret;
659
660         read_lock_irq(&mapping->tree_lock);
661         ret = radix_tree_gang_lookup(&mapping->page_tree,
662                                 (void **)pages, start, nr_pages);
663         for (i = 0; i < ret; i++)
664                 page_cache_get(pages[i]);
665         read_unlock_irq(&mapping->tree_lock);
666         return ret;
667 }
668
669 /*
670  * Like find_get_pages, except we only return pages which are tagged with
671  * `tag'.   We update *index to index the next page for the traversal.
672  */
673 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
674                         int tag, unsigned int nr_pages, struct page **pages)
675 {
676         unsigned int i;
677         unsigned int ret;
678
679         read_lock_irq(&mapping->tree_lock);
680         ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
681                                 (void **)pages, *index, nr_pages, tag);
682         for (i = 0; i < ret; i++)
683                 page_cache_get(pages[i]);
684         if (ret)
685                 *index = pages[ret - 1]->index + 1;
686         read_unlock_irq(&mapping->tree_lock);
687         return ret;
688 }
689
690 /*
691  * Same as grab_cache_page, but do not wait if the page is unavailable.
692  * This is intended for speculative data generators, where the data can
693  * be regenerated if the page couldn't be grabbed.  This routine should
694  * be safe to call while holding the lock for another page.
695  *
696  * Clear __GFP_FS when allocating the page to avoid recursion into the fs
697  * and deadlock against the caller's locked page.
698  */
699 struct page *
700 grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
701 {
702         struct page *page = find_get_page(mapping, index);
703         gfp_t gfp_mask;
704
705         if (page) {
706                 if (!TestSetPageLocked(page))
707                         return page;
708                 page_cache_release(page);
709                 return NULL;
710         }
711         gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
712         page = alloc_pages(gfp_mask, 0);
713         if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
714                 page_cache_release(page);
715                 page = NULL;
716         }
717         return page;
718 }
719
720 EXPORT_SYMBOL(grab_cache_page_nowait);
721
722 /*
723  * This is a generic file read routine, and uses the
724  * mapping->a_ops->readpage() function for the actual low-level
725  * stuff.
726  *
727  * This is really ugly. But the goto's actually try to clarify some
728  * of the logic when it comes to error handling etc.
729  *
730  * Note the struct file* is only passed for the use of readpage.  It may be
731  * NULL.
732  */
733 void do_generic_mapping_read(struct address_space *mapping,
734                              struct file_ra_state *_ra,
735                              struct file *filp,
736                              loff_t *ppos,
737                              read_descriptor_t *desc,
738                              read_actor_t actor)
739 {
740         struct inode *inode = mapping->host;
741         unsigned long index;
742         unsigned long end_index;
743         unsigned long offset;
744         unsigned long last_index;
745         unsigned long next_index;
746         unsigned long prev_index;
747         loff_t isize;
748         struct page *cached_page;
749         int error;
750         struct file_ra_state ra = *_ra;
751
752         cached_page = NULL;
753         index = *ppos >> PAGE_CACHE_SHIFT;
754         next_index = index;
755         prev_index = ra.prev_page;
756         last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
757         offset = *ppos & ~PAGE_CACHE_MASK;
758
759         isize = i_size_read(inode);
760         if (!isize)
761                 goto out;
762
763         end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
764         for (;;) {
765                 struct page *page;
766                 unsigned long nr, ret;
767
768                 /* nr is the maximum number of bytes to copy from this page */
769                 nr = PAGE_CACHE_SIZE;
770                 if (index >= end_index) {
771                         if (index > end_index)
772                                 goto out;
773                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
774                         if (nr <= offset) {
775                                 goto out;
776                         }
777                 }
778                 nr = nr - offset;
779
780                 cond_resched();
781                 if (index == next_index)
782                         next_index = page_cache_readahead(mapping, &ra, filp,
783                                         index, last_index - index);
784
785 find_page:
786                 page = find_get_page(mapping, index);
787                 if (unlikely(page == NULL)) {
788                         handle_ra_miss(mapping, &ra, index);
789                         goto no_cached_page;
790                 }
791                 if (!PageUptodate(page))
792                         goto page_not_up_to_date;
793 page_ok:
794
795                 /* If users can be writing to this page using arbitrary
796                  * virtual addresses, take care about potential aliasing
797                  * before reading the page on the kernel side.
798                  */
799                 if (mapping_writably_mapped(mapping))
800                         flush_dcache_page(page);
801
802                 /*
803                  * When (part of) the same page is read multiple times
804                  * in succession, only mark it as accessed the first time.
805                  */
806                 if (prev_index != index)
807                         mark_page_accessed(page);
808                 prev_index = index;
809
810                 /*
811                  * Ok, we have the page, and it's up-to-date, so
812                  * now we can copy it to user space...
813                  *
814                  * The actor routine returns how many bytes were actually used..
815                  * NOTE! This may not be the same as how much of a user buffer
816                  * we filled up (we may be padding etc), so we can only update
817                  * "pos" here (the actor routine has to update the user buffer
818                  * pointers and the remaining count).
819                  */
820                 ret = actor(desc, page, offset, nr);
821                 offset += ret;
822                 index += offset >> PAGE_CACHE_SHIFT;
823                 offset &= ~PAGE_CACHE_MASK;
824
825                 page_cache_release(page);
826                 if (ret == nr && desc->count)
827                         continue;
828                 goto out;
829
830 page_not_up_to_date:
831                 /* Get exclusive access to the page ... */
832                 lock_page(page);
833
834                 /* Did it get unhashed before we got the lock? */
835                 if (!page->mapping) {
836                         unlock_page(page);
837                         page_cache_release(page);
838                         continue;
839                 }
840
841                 /* Did somebody else fill it already? */
842                 if (PageUptodate(page)) {
843                         unlock_page(page);
844                         goto page_ok;
845                 }
846
847 readpage:
848                 /* Start the actual read. The read will unlock the page. */
849                 error = mapping->a_ops->readpage(filp, page);
850
851                 if (unlikely(error)) {
852                         if (error == AOP_TRUNCATED_PAGE) {
853                                 page_cache_release(page);
854                                 goto find_page;
855                         }
856                         goto readpage_error;
857                 }
858
859                 if (!PageUptodate(page)) {
860                         lock_page(page);
861                         if (!PageUptodate(page)) {
862                                 if (page->mapping == NULL) {
863                                         /*
864                                          * invalidate_inode_pages got it
865                                          */
866                                         unlock_page(page);
867                                         page_cache_release(page);
868                                         goto find_page;
869                                 }
870                                 unlock_page(page);
871                                 error = -EIO;
872                                 goto readpage_error;
873                         }
874                         unlock_page(page);
875                 }
876
877                 /*
878                  * i_size must be checked after we have done ->readpage.
879                  *
880                  * Checking i_size after the readpage allows us to calculate
881                  * the correct value for "nr", which means the zero-filled
882                  * part of the page is not copied back to userspace (unless
883                  * another truncate extends the file - this is desired though).
884                  */
885                 isize = i_size_read(inode);
886                 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
887                 if (unlikely(!isize || index > end_index)) {
888                         page_cache_release(page);
889                         goto out;
890                 }
891
892                 /* nr is the maximum number of bytes to copy from this page */
893                 nr = PAGE_CACHE_SIZE;
894                 if (index == end_index) {
895                         nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
896                         if (nr <= offset) {
897                                 page_cache_release(page);
898                                 goto out;
899                         }
900                 }
901                 nr = nr - offset;
902                 goto page_ok;
903
904 readpage_error:
905                 /* UHHUH! A synchronous read error occurred. Report it */
906                 desc->error = error;
907                 page_cache_release(page);
908                 goto out;
909
910 no_cached_page:
911                 /*
912                  * Ok, it wasn't cached, so we need to create a new
913                  * page..
914                  */
915                 if (!cached_page) {
916                         cached_page = page_cache_alloc_cold(mapping);
917                         if (!cached_page) {
918                                 desc->error = -ENOMEM;
919                                 goto out;
920                         }
921                 }
922                 error = add_to_page_cache_lru(cached_page, mapping,
923                                                 index, GFP_KERNEL);
924                 if (error) {
925                         if (error == -EEXIST)
926                                 goto find_page;
927                         desc->error = error;
928                         goto out;
929                 }
930                 page = cached_page;
931                 cached_page = NULL;
932                 goto readpage;
933         }
934
935 out:
936         *_ra = ra;
937
938         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
939         if (cached_page)
940                 page_cache_release(cached_page);
941         if (filp)
942                 file_accessed(filp);
943 }
944
945 EXPORT_SYMBOL(do_generic_mapping_read);
946
947 int file_read_actor(read_descriptor_t *desc, struct page *page,
948                         unsigned long offset, unsigned long size)
949 {
950         char *kaddr;
951         unsigned long left, count = desc->count;
952
953         if (size > count)
954                 size = count;
955
956         /*
957          * Faults on the destination of a read are common, so do it before
958          * taking the kmap.
959          */
960         if (!fault_in_pages_writeable(desc->arg.buf, size)) {
961                 kaddr = kmap_atomic(page, KM_USER0);
962                 left = __copy_to_user_inatomic(desc->arg.buf,
963                                                 kaddr + offset, size);
964                 kunmap_atomic(kaddr, KM_USER0);
965                 if (left == 0)
966                         goto success;
967         }
968
969         /* Do it the slow way */
970         kaddr = kmap(page);
971         left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
972         kunmap(page);
973
974         if (left) {
975                 size -= left;
976                 desc->error = -EFAULT;
977         }
978 success:
979         desc->count = count - size;
980         desc->written += size;
981         desc->arg.buf += size;
982         return size;
983 }
984
985 /*
986  * This is the "read()" routine for all filesystems
987  * that can use the page cache directly.
988  */
989 ssize_t
990 __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
991                 unsigned long nr_segs, loff_t *ppos)
992 {
993         struct file *filp = iocb->ki_filp;
994         ssize_t retval;
995         unsigned long seg;
996         size_t count;
997
998         count = 0;
999         for (seg = 0; seg < nr_segs; seg++) {
1000                 const struct iovec *iv = &iov[seg];
1001
1002                 /*
1003                  * If any segment has a negative length, or the cumulative
1004                  * length ever wraps negative then return -EINVAL.
1005                  */
1006                 count += iv->iov_len;
1007                 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1008                         return -EINVAL;
1009                 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1010                         continue;
1011                 if (seg == 0)
1012                         return -EFAULT;
1013                 nr_segs = seg;
1014                 count -= iv->iov_len;   /* This segment is no good */
1015                 break;
1016         }
1017
1018         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1019         if (filp->f_flags & O_DIRECT) {
1020                 loff_t pos = *ppos, size;
1021                 struct address_space *mapping;
1022                 struct inode *inode;
1023
1024                 mapping = filp->f_mapping;
1025                 inode = mapping->host;
1026                 retval = 0;
1027                 if (!count)
1028                         goto out; /* skip atime */
1029                 size = i_size_read(inode);
1030                 if (pos < size) {
1031                         retval = generic_file_direct_IO(READ, iocb,
1032                                                 iov, pos, nr_segs);
1033                         if (retval > 0 && !is_sync_kiocb(iocb))
1034                                 retval = -EIOCBQUEUED;
1035                         if (retval > 0)
1036                                 *ppos = pos + retval;
1037                 }
1038                 file_accessed(filp);
1039                 goto out;
1040         }
1041
1042         retval = 0;
1043         if (count) {
1044                 for (seg = 0; seg < nr_segs; seg++) {
1045                         read_descriptor_t desc;
1046
1047                         desc.written = 0;
1048                         desc.arg.buf = iov[seg].iov_base;
1049                         desc.count = iov[seg].iov_len;
1050                         if (desc.count == 0)
1051                                 continue;
1052                         desc.error = 0;
1053                         do_generic_file_read(filp,ppos,&desc,file_read_actor);
1054                         retval += desc.written;
1055                         if (desc.error) {
1056                                 retval = retval ?: desc.error;
1057                                 break;
1058                         }
1059                 }
1060         }
1061 out:
1062         return retval;
1063 }
1064
1065 EXPORT_SYMBOL(__generic_file_aio_read);
1066
1067 ssize_t
1068 generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1069 {
1070         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1071
1072         BUG_ON(iocb->ki_pos != pos);
1073         return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1074 }
1075
1076 EXPORT_SYMBOL(generic_file_aio_read);
1077
1078 ssize_t
1079 generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1080 {
1081         struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1082         struct kiocb kiocb;
1083         ssize_t ret;
1084
1085         init_sync_kiocb(&kiocb, filp);
1086         ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1087         if (-EIOCBQUEUED == ret)
1088                 ret = wait_on_sync_kiocb(&kiocb);
1089         return ret;
1090 }
1091
1092 EXPORT_SYMBOL(generic_file_read);
1093
1094 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1095 {
1096         ssize_t written;
1097         unsigned long count = desc->count;
1098         struct file *file = desc->arg.data;
1099
1100         if (size > count)
1101                 size = count;
1102
1103         written = file->f_op->sendpage(file, page, offset,
1104                                        size, &file->f_pos, size<count);
1105         if (written < 0) {
1106                 desc->error = written;
1107                 written = 0;
1108         }
1109         desc->count = count - written;
1110         desc->written += written;
1111         return written;
1112 }
1113
1114 ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1115                          size_t count, read_actor_t actor, void *target)
1116 {
1117         read_descriptor_t desc;
1118
1119         if (!count)
1120                 return 0;
1121
1122         desc.written = 0;
1123         desc.count = count;
1124         desc.arg.data = target;
1125         desc.error = 0;
1126
1127         do_generic_file_read(in_file, ppos, &desc, actor);
1128         if (desc.written)
1129                 return desc.written;
1130         return desc.error;
1131 }
1132
1133 EXPORT_SYMBOL(generic_file_sendfile);
1134
1135 static ssize_t
1136 do_readahead(struct address_space *mapping, struct file *filp,
1137              unsigned long index, unsigned long nr)
1138 {
1139         if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1140                 return -EINVAL;
1141
1142         force_page_cache_readahead(mapping, filp, index,
1143                                         max_sane_readahead(nr));
1144         return 0;
1145 }
1146
1147 asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1148 {
1149         ssize_t ret;
1150         struct file *file;
1151
1152         ret = -EBADF;
1153         file = fget(fd);
1154         if (file) {
1155                 if (file->f_mode & FMODE_READ) {
1156                         struct address_space *mapping = file->f_mapping;
1157                         unsigned long start = offset >> PAGE_CACHE_SHIFT;
1158                         unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1159                         unsigned long len = end - start + 1;
1160                         ret = do_readahead(mapping, file, start, len);
1161                 }
1162                 fput(file);
1163         }
1164         return ret;
1165 }
1166
1167 #ifdef CONFIG_MMU
1168 /*
1169  * This adds the requested page to the page cache if it isn't already there,
1170  * and schedules an I/O to read in its contents from disk.
1171  */
1172 static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1173 static int fastcall page_cache_read(struct file * file, unsigned long offset)
1174 {
1175         struct address_space *mapping = file->f_mapping;
1176         struct page *page; 
1177         int ret;
1178
1179         do {
1180                 page = page_cache_alloc_cold(mapping);
1181                 if (!page)
1182                         return -ENOMEM;
1183
1184                 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1185                 if (ret == 0)
1186                         ret = mapping->a_ops->readpage(file, page);
1187                 else if (ret == -EEXIST)
1188                         ret = 0; /* losing race to add is OK */
1189
1190                 page_cache_release(page);
1191
1192         } while (ret == AOP_TRUNCATED_PAGE);
1193                 
1194         return ret;
1195 }
1196
1197 #define MMAP_LOTSAMISS  (100)
1198
1199 /*
1200  * filemap_nopage() is invoked via the vma operations vector for a
1201  * mapped memory region to read in file data during a page fault.
1202  *
1203  * The goto's are kind of ugly, but this streamlines the normal case of having
1204  * it in the page cache, and handles the special cases reasonably without
1205  * having a lot of duplicated code.
1206  */
1207 struct page *filemap_nopage(struct vm_area_struct *area,
1208                                 unsigned long address, int *type)
1209 {
1210         int error;
1211         struct file *file = area->vm_file;
1212         struct address_space *mapping = file->f_mapping;
1213         struct file_ra_state *ra = &file->f_ra;
1214         struct inode *inode = mapping->host;
1215         struct page *page;
1216         unsigned long size, pgoff;
1217         int did_readaround = 0, majmin = VM_FAULT_MINOR;
1218
1219         pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1220
1221 retry_all:
1222         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1223         if (pgoff >= size)
1224                 goto outside_data_content;
1225
1226         /* If we don't want any read-ahead, don't bother */
1227         if (VM_RandomReadHint(area))
1228                 goto no_cached_page;
1229
1230         /*
1231          * The readahead code wants to be told about each and every page
1232          * so it can build and shrink its windows appropriately
1233          *
1234          * For sequential accesses, we use the generic readahead logic.
1235          */
1236         if (VM_SequentialReadHint(area))
1237                 page_cache_readahead(mapping, ra, file, pgoff, 1);
1238
1239         /*
1240          * Do we have something in the page cache already?
1241          */
1242 retry_find:
1243         page = find_get_page(mapping, pgoff);
1244         if (!page) {
1245                 unsigned long ra_pages;
1246
1247                 if (VM_SequentialReadHint(area)) {
1248                         handle_ra_miss(mapping, ra, pgoff);
1249                         goto no_cached_page;
1250                 }
1251                 ra->mmap_miss++;
1252
1253                 /*
1254                  * Do we miss much more than hit in this file? If so,
1255                  * stop bothering with read-ahead. It will only hurt.
1256                  */
1257                 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1258                         goto no_cached_page;
1259
1260                 /*
1261                  * To keep the pgmajfault counter straight, we need to
1262                  * check did_readaround, as this is an inner loop.
1263                  */
1264                 if (!did_readaround) {
1265                         majmin = VM_FAULT_MAJOR;
1266                         inc_page_state(pgmajfault);
1267                 }
1268                 did_readaround = 1;
1269                 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1270                 if (ra_pages) {
1271                         pgoff_t start = 0;
1272
1273                         if (pgoff > ra_pages / 2)
1274                                 start = pgoff - ra_pages / 2;
1275                         do_page_cache_readahead(mapping, file, start, ra_pages);
1276                 }
1277                 page = find_get_page(mapping, pgoff);
1278                 if (!page)
1279                         goto no_cached_page;
1280         }
1281
1282         if (!did_readaround)
1283                 ra->mmap_hit++;
1284
1285         /*
1286          * Ok, found a page in the page cache, now we need to check
1287          * that it's up-to-date.
1288          */
1289         if (!PageUptodate(page))
1290                 goto page_not_uptodate;
1291
1292 success:
1293         /*
1294          * Found the page and have a reference on it.
1295          */
1296         mark_page_accessed(page);
1297         if (type)
1298                 *type = majmin;
1299         return page;
1300
1301 outside_data_content:
1302         /*
1303          * An external ptracer can access pages that normally aren't
1304          * accessible..
1305          */
1306         if (area->vm_mm == current->mm)
1307                 return NULL;
1308         /* Fall through to the non-read-ahead case */
1309 no_cached_page:
1310         /*
1311          * We're only likely to ever get here if MADV_RANDOM is in
1312          * effect.
1313          */
1314         error = page_cache_read(file, pgoff);
1315         grab_swap_token();
1316
1317         /*
1318          * The page we want has now been added to the page cache.
1319          * In the unlikely event that someone removed it in the
1320          * meantime, we'll just come back here and read it again.
1321          */
1322         if (error >= 0)
1323                 goto retry_find;
1324
1325         /*
1326          * An error return from page_cache_read can result if the
1327          * system is low on memory, or a problem occurs while trying
1328          * to schedule I/O.
1329          */
1330         if (error == -ENOMEM)
1331                 return NOPAGE_OOM;
1332         return NULL;
1333
1334 page_not_uptodate:
1335         if (!did_readaround) {
1336                 majmin = VM_FAULT_MAJOR;
1337                 inc_page_state(pgmajfault);
1338         }
1339         lock_page(page);
1340
1341         /* Did it get unhashed while we waited for it? */
1342         if (!page->mapping) {
1343                 unlock_page(page);
1344                 page_cache_release(page);
1345                 goto retry_all;
1346         }
1347
1348         /* Did somebody else get it up-to-date? */
1349         if (PageUptodate(page)) {
1350                 unlock_page(page);
1351                 goto success;
1352         }
1353
1354         error = mapping->a_ops->readpage(file, page);
1355         if (!error) {
1356                 wait_on_page_locked(page);
1357                 if (PageUptodate(page))
1358                         goto success;
1359         } else if (error == AOP_TRUNCATED_PAGE) {
1360                 page_cache_release(page);
1361                 goto retry_find;
1362         }
1363
1364         /*
1365          * Umm, take care of errors if the page isn't up-to-date.
1366          * Try to re-read it _once_. We do this synchronously,
1367          * because there really aren't any performance issues here
1368          * and we need to check for errors.
1369          */
1370         lock_page(page);
1371
1372         /* Somebody truncated the page on us? */
1373         if (!page->mapping) {
1374                 unlock_page(page);
1375                 page_cache_release(page);
1376                 goto retry_all;
1377         }
1378
1379         /* Somebody else successfully read it in? */
1380         if (PageUptodate(page)) {
1381                 unlock_page(page);
1382                 goto success;
1383         }
1384         ClearPageError(page);
1385         error = mapping->a_ops->readpage(file, page);
1386         if (!error) {
1387                 wait_on_page_locked(page);
1388                 if (PageUptodate(page))
1389                         goto success;
1390         } else if (error == AOP_TRUNCATED_PAGE) {
1391                 page_cache_release(page);
1392                 goto retry_find;
1393         }
1394
1395         /*
1396          * Things didn't work out. Return zero to tell the
1397          * mm layer so, possibly freeing the page cache page first.
1398          */
1399         page_cache_release(page);
1400         return NULL;
1401 }
1402
1403 EXPORT_SYMBOL(filemap_nopage);
1404
1405 static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1406                                         int nonblock)
1407 {
1408         struct address_space *mapping = file->f_mapping;
1409         struct page *page;
1410         int error;
1411
1412         /*
1413          * Do we have something in the page cache already?
1414          */
1415 retry_find:
1416         page = find_get_page(mapping, pgoff);
1417         if (!page) {
1418                 if (nonblock)
1419                         return NULL;
1420                 goto no_cached_page;
1421         }
1422
1423         /*
1424          * Ok, found a page in the page cache, now we need to check
1425          * that it's up-to-date.
1426          */
1427         if (!PageUptodate(page)) {
1428                 if (nonblock) {
1429                         page_cache_release(page);
1430                         return NULL;
1431                 }
1432                 goto page_not_uptodate;
1433         }
1434
1435 success:
1436         /*
1437          * Found the page and have a reference on it.
1438          */
1439         mark_page_accessed(page);
1440         return page;
1441
1442 no_cached_page:
1443         error = page_cache_read(file, pgoff);
1444
1445         /*
1446          * The page we want has now been added to the page cache.
1447          * In the unlikely event that someone removed it in the
1448          * meantime, we'll just come back here and read it again.
1449          */
1450         if (error >= 0)
1451                 goto retry_find;
1452
1453         /*
1454          * An error return from page_cache_read can result if the
1455          * system is low on memory, or a problem occurs while trying
1456          * to schedule I/O.
1457          */
1458         return NULL;
1459
1460 page_not_uptodate:
1461         lock_page(page);
1462
1463         /* Did it get unhashed while we waited for it? */
1464         if (!page->mapping) {
1465                 unlock_page(page);
1466                 goto err;
1467         }
1468
1469         /* Did somebody else get it up-to-date? */
1470         if (PageUptodate(page)) {
1471                 unlock_page(page);
1472                 goto success;
1473         }
1474
1475         error = mapping->a_ops->readpage(file, page);
1476         if (!error) {
1477                 wait_on_page_locked(page);
1478                 if (PageUptodate(page))
1479                         goto success;
1480         } else if (error == AOP_TRUNCATED_PAGE) {
1481                 page_cache_release(page);
1482                 goto retry_find;
1483         }
1484
1485         /*
1486          * Umm, take care of errors if the page isn't up-to-date.
1487          * Try to re-read it _once_. We do this synchronously,
1488          * because there really aren't any performance issues here
1489          * and we need to check for errors.
1490          */
1491         lock_page(page);
1492
1493         /* Somebody truncated the page on us? */
1494         if (!page->mapping) {
1495                 unlock_page(page);
1496                 goto err;
1497         }
1498         /* Somebody else successfully read it in? */
1499         if (PageUptodate(page)) {
1500                 unlock_page(page);
1501                 goto success;
1502         }
1503
1504         ClearPageError(page);
1505         error = mapping->a_ops->readpage(file, page);
1506         if (!error) {
1507                 wait_on_page_locked(page);
1508                 if (PageUptodate(page))
1509                         goto success;
1510         } else if (error == AOP_TRUNCATED_PAGE) {
1511                 page_cache_release(page);
1512                 goto retry_find;
1513         }
1514
1515         /*
1516          * Things didn't work out. Return zero to tell the
1517          * mm layer so, possibly freeing the page cache page first.
1518          */
1519 err:
1520         page_cache_release(page);
1521
1522         return NULL;
1523 }
1524
1525 int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1526                 unsigned long len, pgprot_t prot, unsigned long pgoff,
1527                 int nonblock)
1528 {
1529         struct file *file = vma->vm_file;
1530         struct address_space *mapping = file->f_mapping;
1531         struct inode *inode = mapping->host;
1532         unsigned long size;
1533         struct mm_struct *mm = vma->vm_mm;
1534         struct page *page;
1535         int err;
1536
1537         if (!nonblock)
1538                 force_page_cache_readahead(mapping, vma->vm_file,
1539                                         pgoff, len >> PAGE_CACHE_SHIFT);
1540
1541 repeat:
1542         size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1543         if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1544                 return -EINVAL;
1545
1546         page = filemap_getpage(file, pgoff, nonblock);
1547
1548         /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1549          * done in shmem_populate calling shmem_getpage */
1550         if (!page && !nonblock)
1551                 return -ENOMEM;
1552
1553         if (page) {
1554                 err = install_page(mm, vma, addr, page, prot);
1555                 if (err) {
1556                         page_cache_release(page);
1557                         return err;
1558                 }
1559         } else if (vma->vm_flags & VM_NONLINEAR) {
1560                 /* No page was found just because we can't read it in now (being
1561                  * here implies nonblock != 0), but the page may exist, so set
1562                  * the PTE to fault it in later. */
1563                 err = install_file_pte(mm, vma, addr, pgoff, prot);
1564                 if (err)
1565                         return err;
1566         }
1567
1568         len -= PAGE_SIZE;
1569         addr += PAGE_SIZE;
1570         pgoff++;
1571         if (len)
1572                 goto repeat;
1573
1574         return 0;
1575 }
1576 EXPORT_SYMBOL(filemap_populate);
1577
1578 struct vm_operations_struct generic_file_vm_ops = {
1579         .nopage         = filemap_nopage,
1580         .populate       = filemap_populate,
1581 };
1582
1583 /* This is used for a general mmap of a disk file */
1584
1585 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1586 {
1587         struct address_space *mapping = file->f_mapping;
1588
1589         if (!mapping->a_ops->readpage)
1590                 return -ENOEXEC;
1591         file_accessed(file);
1592         vma->vm_ops = &generic_file_vm_ops;
1593         return 0;
1594 }
1595
1596 /*
1597  * This is for filesystems which do not implement ->writepage.
1598  */
1599 int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1600 {
1601         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1602                 return -EINVAL;
1603         return generic_file_mmap(file, vma);
1604 }
1605 #else
1606 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1607 {
1608         return -ENOSYS;
1609 }
1610 int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1611 {
1612         return -ENOSYS;
1613 }
1614 #endif /* CONFIG_MMU */
1615
1616 EXPORT_SYMBOL(generic_file_mmap);
1617 EXPORT_SYMBOL(generic_file_readonly_mmap);
1618
1619 static inline struct page *__read_cache_page(struct address_space *mapping,
1620                                 unsigned long index,
1621                                 int (*filler)(void *,struct page*),
1622                                 void *data)
1623 {
1624         struct page *page, *cached_page = NULL;
1625         int err;
1626 repeat:
1627         page = find_get_page(mapping, index);
1628         if (!page) {
1629                 if (!cached_page) {
1630                         cached_page = page_cache_alloc_cold(mapping);
1631                         if (!cached_page)
1632                                 return ERR_PTR(-ENOMEM);
1633                 }
1634                 err = add_to_page_cache_lru(cached_page, mapping,
1635                                         index, GFP_KERNEL);
1636                 if (err == -EEXIST)
1637                         goto repeat;
1638                 if (err < 0) {
1639                         /* Presumably ENOMEM for radix tree node */
1640                         page_cache_release(cached_page);
1641                         return ERR_PTR(err);
1642                 }
1643                 page = cached_page;
1644                 cached_page = NULL;
1645                 err = filler(data, page);
1646                 if (err < 0) {
1647                         page_cache_release(page);
1648                         page = ERR_PTR(err);
1649                 }
1650         }
1651         if (cached_page)
1652                 page_cache_release(cached_page);
1653         return page;
1654 }
1655
1656 /*
1657  * Read into the page cache. If a page already exists,
1658  * and PageUptodate() is not set, try to fill the page.
1659  */
1660 struct page *read_cache_page(struct address_space *mapping,
1661                                 unsigned long index,
1662                                 int (*filler)(void *,struct page*),
1663                                 void *data)
1664 {
1665         struct page *page;
1666         int err;
1667
1668 retry:
1669         page = __read_cache_page(mapping, index, filler, data);
1670         if (IS_ERR(page))
1671                 goto out;
1672         mark_page_accessed(page);
1673         if (PageUptodate(page))
1674                 goto out;
1675
1676         lock_page(page);
1677         if (!page->mapping) {
1678                 unlock_page(page);
1679                 page_cache_release(page);
1680                 goto retry;
1681         }
1682         if (PageUptodate(page)) {
1683                 unlock_page(page);
1684                 goto out;
1685         }
1686         err = filler(data, page);
1687         if (err < 0) {
1688                 page_cache_release(page);
1689                 page = ERR_PTR(err);
1690         }
1691  out:
1692         return page;
1693 }
1694
1695 EXPORT_SYMBOL(read_cache_page);
1696
1697 /*
1698  * If the page was newly created, increment its refcount and add it to the
1699  * caller's lru-buffering pagevec.  This function is specifically for
1700  * generic_file_write().
1701  */
1702 static inline struct page *
1703 __grab_cache_page(struct address_space *mapping, unsigned long index,
1704                         struct page **cached_page, struct pagevec *lru_pvec)
1705 {
1706         int err;
1707         struct page *page;
1708 repeat:
1709         page = find_lock_page(mapping, index);
1710         if (!page) {
1711                 if (!*cached_page) {
1712                         *cached_page = page_cache_alloc(mapping);
1713                         if (!*cached_page)
1714                                 return NULL;
1715                 }
1716                 err = add_to_page_cache(*cached_page, mapping,
1717                                         index, GFP_KERNEL);
1718                 if (err == -EEXIST)
1719                         goto repeat;
1720                 if (err == 0) {
1721                         page = *cached_page;
1722                         page_cache_get(page);
1723                         if (!pagevec_add(lru_pvec, page))
1724                                 __pagevec_lru_add(lru_pvec);
1725                         *cached_page = NULL;
1726                 }
1727         }
1728         return page;
1729 }
1730
1731 /*
1732  * The logic we want is
1733  *
1734  *      if suid or (sgid and xgrp)
1735  *              remove privs
1736  */
1737 int remove_suid(struct dentry *dentry)
1738 {
1739         mode_t mode = dentry->d_inode->i_mode;
1740         int kill = 0;
1741         int result = 0;
1742
1743         /* suid always must be killed */
1744         if (unlikely(mode & S_ISUID))
1745                 kill = ATTR_KILL_SUID;
1746
1747         /*
1748          * sgid without any exec bits is just a mandatory locking mark; leave
1749          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1750          */
1751         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1752                 kill |= ATTR_KILL_SGID;
1753
1754         if (unlikely(kill && !capable(CAP_FSETID))) {
1755                 struct iattr newattrs;
1756
1757                 newattrs.ia_valid = ATTR_FORCE | kill;
1758                 result = notify_change(dentry, &newattrs);
1759         }
1760         return result;
1761 }
1762 EXPORT_SYMBOL(remove_suid);
1763
1764 size_t
1765 __filemap_copy_from_user_iovec(char *vaddr, 
1766                         const struct iovec *iov, size_t base, size_t bytes)
1767 {
1768         size_t copied = 0, left = 0;
1769
1770         while (bytes) {
1771                 char __user *buf = iov->iov_base + base;
1772                 int copy = min(bytes, iov->iov_len - base);
1773
1774                 base = 0;
1775                 left = __copy_from_user_inatomic(vaddr, buf, copy);
1776                 copied += copy;
1777                 bytes -= copy;
1778                 vaddr += copy;
1779                 iov++;
1780
1781                 if (unlikely(left)) {
1782                         /* zero the rest of the target like __copy_from_user */
1783                         if (bytes)
1784                                 memset(vaddr, 0, bytes);
1785                         break;
1786                 }
1787         }
1788         return copied - left;
1789 }
1790
1791 /*
1792  * Performs necessary checks before doing a write
1793  *
1794  * Can adjust writing position aor amount of bytes to write.
1795  * Returns appropriate error code that caller should return or
1796  * zero in case that write should be allowed.
1797  */
1798 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1799 {
1800         struct inode *inode = file->f_mapping->host;
1801         unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1802
1803         if (unlikely(*pos < 0))
1804                 return -EINVAL;
1805
1806         if (!isblk) {
1807                 /* FIXME: this is for backwards compatibility with 2.4 */
1808                 if (file->f_flags & O_APPEND)
1809                         *pos = i_size_read(inode);
1810
1811                 if (limit != RLIM_INFINITY) {
1812                         if (*pos >= limit) {
1813                                 send_sig(SIGXFSZ, current, 0);
1814                                 return -EFBIG;
1815                         }
1816                         if (*count > limit - (typeof(limit))*pos) {
1817                                 *count = limit - (typeof(limit))*pos;
1818                         }
1819                 }
1820         }
1821
1822         /*
1823          * LFS rule
1824          */
1825         if (unlikely(*pos + *count > MAX_NON_LFS &&
1826                                 !(file->f_flags & O_LARGEFILE))) {
1827                 if (*pos >= MAX_NON_LFS) {
1828                         send_sig(SIGXFSZ, current, 0);
1829                         return -EFBIG;
1830                 }
1831                 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1832                         *count = MAX_NON_LFS - (unsigned long)*pos;
1833                 }
1834         }
1835
1836         /*
1837          * Are we about to exceed the fs block limit ?
1838          *
1839          * If we have written data it becomes a short write.  If we have
1840          * exceeded without writing data we send a signal and return EFBIG.
1841          * Linus frestrict idea will clean these up nicely..
1842          */
1843         if (likely(!isblk)) {
1844                 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1845                         if (*count || *pos > inode->i_sb->s_maxbytes) {
1846                                 send_sig(SIGXFSZ, current, 0);
1847                                 return -EFBIG;
1848                         }
1849                         /* zero-length writes at ->s_maxbytes are OK */
1850                 }
1851
1852                 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1853                         *count = inode->i_sb->s_maxbytes - *pos;
1854         } else {
1855                 loff_t isize;
1856                 if (bdev_read_only(I_BDEV(inode)))
1857                         return -EPERM;
1858                 isize = i_size_read(inode);
1859                 if (*pos >= isize) {
1860                         if (*count || *pos > isize)
1861                                 return -ENOSPC;
1862                 }
1863
1864                 if (*pos + *count > isize)
1865                         *count = isize - *pos;
1866         }
1867         return 0;
1868 }
1869 EXPORT_SYMBOL(generic_write_checks);
1870
1871 ssize_t
1872 generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1873                 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1874                 size_t count, size_t ocount)
1875 {
1876         struct file     *file = iocb->ki_filp;
1877         struct address_space *mapping = file->f_mapping;
1878         struct inode    *inode = mapping->host;
1879         ssize_t         written;
1880
1881         if (count != ocount)
1882                 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1883
1884         written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1885         if (written > 0) {
1886                 loff_t end = pos + written;
1887                 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1888                         i_size_write(inode,  end);
1889                         mark_inode_dirty(inode);
1890                 }
1891                 *ppos = end;
1892         }
1893
1894         /*
1895          * Sync the fs metadata but not the minor inode changes and
1896          * of course not the data as we did direct DMA for the IO.
1897          * i_mutex is held, which protects generic_osync_inode() from
1898          * livelocking.
1899          */
1900         if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1901                 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1902                 if (err < 0)
1903                         written = err;
1904         }
1905         if (written == count && !is_sync_kiocb(iocb))
1906                 written = -EIOCBQUEUED;
1907         return written;
1908 }
1909 EXPORT_SYMBOL(generic_file_direct_write);
1910
1911 ssize_t
1912 generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1913                 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1914                 size_t count, ssize_t written)
1915 {
1916         struct file *file = iocb->ki_filp;
1917         struct address_space * mapping = file->f_mapping;
1918         struct address_space_operations *a_ops = mapping->a_ops;
1919         struct inode    *inode = mapping->host;
1920         long            status = 0;
1921         struct page     *page;
1922         struct page     *cached_page = NULL;
1923         size_t          bytes;
1924         struct pagevec  lru_pvec;
1925         const struct iovec *cur_iov = iov; /* current iovec */
1926         size_t          iov_base = 0;      /* offset in the current iovec */
1927         char __user     *buf;
1928
1929         pagevec_init(&lru_pvec, 0);
1930
1931         /*
1932          * handle partial DIO write.  Adjust cur_iov if needed.
1933          */
1934         if (likely(nr_segs == 1))
1935                 buf = iov->iov_base + written;
1936         else {
1937                 filemap_set_next_iovec(&cur_iov, &iov_base, written);
1938                 buf = cur_iov->iov_base + iov_base;
1939         }
1940
1941         do {
1942                 unsigned long index;
1943                 unsigned long offset;
1944                 unsigned long maxlen;
1945                 size_t copied;
1946
1947                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1948                 index = pos >> PAGE_CACHE_SHIFT;
1949                 bytes = PAGE_CACHE_SIZE - offset;
1950                 if (bytes > count)
1951                         bytes = count;
1952
1953                 /*
1954                  * Bring in the user page that we will copy from _first_.
1955                  * Otherwise there's a nasty deadlock on copying from the
1956                  * same page as we're writing to, without it being marked
1957                  * up-to-date.
1958                  */
1959                 maxlen = cur_iov->iov_len - iov_base;
1960                 if (maxlen > bytes)
1961                         maxlen = bytes;
1962                 fault_in_pages_readable(buf, maxlen);
1963
1964                 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1965                 if (!page) {
1966                         status = -ENOMEM;
1967                         break;
1968                 }
1969
1970                 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1971                 if (unlikely(status)) {
1972                         loff_t isize = i_size_read(inode);
1973
1974                         if (status != AOP_TRUNCATED_PAGE)
1975                                 unlock_page(page);
1976                         page_cache_release(page);
1977                         if (status == AOP_TRUNCATED_PAGE)
1978                                 continue;
1979                         /*
1980                          * prepare_write() may have instantiated a few blocks
1981                          * outside i_size.  Trim these off again.
1982                          */
1983                         if (pos + bytes > isize)
1984                                 vmtruncate(inode, isize);
1985                         break;
1986                 }
1987                 if (likely(nr_segs == 1))
1988                         copied = filemap_copy_from_user(page, offset,
1989                                                         buf, bytes);
1990                 else
1991                         copied = filemap_copy_from_user_iovec(page, offset,
1992                                                 cur_iov, iov_base, bytes);
1993                 flush_dcache_page(page);
1994                 status = a_ops->commit_write(file, page, offset, offset+bytes);
1995                 if (status == AOP_TRUNCATED_PAGE) {
1996                         page_cache_release(page);
1997                         continue;
1998                 }
1999                 if (likely(copied > 0)) {
2000                         if (!status)
2001                                 status = copied;
2002
2003                         if (status >= 0) {
2004                                 written += status;
2005                                 count -= status;
2006                                 pos += status;
2007                                 buf += status;
2008                                 if (unlikely(nr_segs > 1)) {
2009                                         filemap_set_next_iovec(&cur_iov,
2010                                                         &iov_base, status);
2011                                         if (count)
2012                                                 buf = cur_iov->iov_base +
2013                                                         iov_base;
2014                                 } else {
2015                                         iov_base += status;
2016                                 }
2017                         }
2018                 }
2019                 if (unlikely(copied != bytes))
2020                         if (status >= 0)
2021                                 status = -EFAULT;
2022                 unlock_page(page);
2023                 mark_page_accessed(page);
2024                 page_cache_release(page);
2025                 if (status < 0)
2026                         break;
2027                 balance_dirty_pages_ratelimited(mapping);
2028                 cond_resched();
2029         } while (count);
2030         *ppos = pos;
2031
2032         if (cached_page)
2033                 page_cache_release(cached_page);
2034
2035         /*
2036          * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2037          */
2038         if (likely(status >= 0)) {
2039                 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2040                         if (!a_ops->writepage || !is_sync_kiocb(iocb))
2041                                 status = generic_osync_inode(inode, mapping,
2042                                                 OSYNC_METADATA|OSYNC_DATA);
2043                 }
2044         }
2045         
2046         /*
2047          * If we get here for O_DIRECT writes then we must have fallen through
2048          * to buffered writes (block instantiation inside i_size).  So we sync
2049          * the file data here, to try to honour O_DIRECT expectations.
2050          */
2051         if (unlikely(file->f_flags & O_DIRECT) && written)
2052                 status = filemap_write_and_wait(mapping);
2053
2054         pagevec_lru_add(&lru_pvec);
2055         return written ? written : status;
2056 }
2057 EXPORT_SYMBOL(generic_file_buffered_write);
2058
2059 static ssize_t
2060 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2061                                 unsigned long nr_segs, loff_t *ppos)
2062 {
2063         struct file *file = iocb->ki_filp;
2064         struct address_space * mapping = file->f_mapping;
2065         size_t ocount;          /* original count */
2066         size_t count;           /* after file limit checks */
2067         struct inode    *inode = mapping->host;
2068         unsigned long   seg;
2069         loff_t          pos;
2070         ssize_t         written;
2071         ssize_t         err;
2072
2073         ocount = 0;
2074         for (seg = 0; seg < nr_segs; seg++) {
2075                 const struct iovec *iv = &iov[seg];
2076
2077                 /*
2078                  * If any segment has a negative length, or the cumulative
2079                  * length ever wraps negative then return -EINVAL.
2080                  */
2081                 ocount += iv->iov_len;
2082                 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2083                         return -EINVAL;
2084                 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2085                         continue;
2086                 if (seg == 0)
2087                         return -EFAULT;
2088                 nr_segs = seg;
2089                 ocount -= iv->iov_len;  /* This segment is no good */
2090                 break;
2091         }
2092
2093         count = ocount;
2094         pos = *ppos;
2095
2096         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2097
2098         /* We can write back this queue in page reclaim */
2099         current->backing_dev_info = mapping->backing_dev_info;
2100         written = 0;
2101
2102         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2103         if (err)
2104                 goto out;
2105
2106         if (count == 0)
2107                 goto out;
2108
2109         err = remove_suid(file->f_dentry);
2110         if (err)
2111                 goto out;
2112
2113         file_update_time(file);
2114
2115         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2116         if (unlikely(file->f_flags & O_DIRECT)) {
2117                 written = generic_file_direct_write(iocb, iov,
2118                                 &nr_segs, pos, ppos, count, ocount);
2119                 if (written < 0 || written == count)
2120                         goto out;
2121                 /*
2122                  * direct-io write to a hole: fall through to buffered I/O
2123                  * for completing the rest of the request.
2124                  */
2125                 pos += written;
2126                 count -= written;
2127         }
2128
2129         written = generic_file_buffered_write(iocb, iov, nr_segs,
2130                         pos, ppos, count, written);
2131 out:
2132         current->backing_dev_info = NULL;
2133         return written ? written : err;
2134 }
2135 EXPORT_SYMBOL(generic_file_aio_write_nolock);
2136
2137 ssize_t
2138 generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2139                                 unsigned long nr_segs, loff_t *ppos)
2140 {
2141         struct file *file = iocb->ki_filp;
2142         struct address_space *mapping = file->f_mapping;
2143         struct inode *inode = mapping->host;
2144         ssize_t ret;
2145         loff_t pos = *ppos;
2146
2147         ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2148
2149         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2150                 int err;
2151
2152                 err = sync_page_range_nolock(inode, mapping, pos, ret);
2153                 if (err < 0)
2154                         ret = err;
2155         }
2156         return ret;
2157 }
2158
2159 static ssize_t
2160 __generic_file_write_nolock(struct file *file, const struct iovec *iov,
2161                                 unsigned long nr_segs, loff_t *ppos)
2162 {
2163         struct kiocb kiocb;
2164         ssize_t ret;
2165
2166         init_sync_kiocb(&kiocb, file);
2167         ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2168         if (ret == -EIOCBQUEUED)
2169                 ret = wait_on_sync_kiocb(&kiocb);
2170         return ret;
2171 }
2172
2173 ssize_t
2174 generic_file_write_nolock(struct file *file, const struct iovec *iov,
2175                                 unsigned long nr_segs, loff_t *ppos)
2176 {
2177         struct kiocb kiocb;
2178         ssize_t ret;
2179
2180         init_sync_kiocb(&kiocb, file);
2181         ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2182         if (-EIOCBQUEUED == ret)
2183                 ret = wait_on_sync_kiocb(&kiocb);
2184         return ret;
2185 }
2186 EXPORT_SYMBOL(generic_file_write_nolock);
2187
2188 ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2189                                size_t count, loff_t pos)
2190 {
2191         struct file *file = iocb->ki_filp;
2192         struct address_space *mapping = file->f_mapping;
2193         struct inode *inode = mapping->host;
2194         ssize_t ret;
2195         struct iovec local_iov = { .iov_base = (void __user *)buf,
2196                                         .iov_len = count };
2197
2198         BUG_ON(iocb->ki_pos != pos);
2199
2200         mutex_lock(&inode->i_mutex);
2201         ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2202                                                 &iocb->ki_pos);
2203         mutex_unlock(&inode->i_mutex);
2204
2205         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2206                 ssize_t err;
2207
2208                 err = sync_page_range(inode, mapping, pos, ret);
2209                 if (err < 0)
2210                         ret = err;
2211         }
2212         return ret;
2213 }
2214 EXPORT_SYMBOL(generic_file_aio_write);
2215
2216 ssize_t generic_file_write(struct file *file, const char __user *buf,
2217                            size_t count, loff_t *ppos)
2218 {
2219         struct address_space *mapping = file->f_mapping;
2220         struct inode *inode = mapping->host;
2221         ssize_t ret;
2222         struct iovec local_iov = { .iov_base = (void __user *)buf,
2223                                         .iov_len = count };
2224
2225         mutex_lock(&inode->i_mutex);
2226         ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2227         mutex_unlock(&inode->i_mutex);
2228
2229         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2230                 ssize_t err;
2231
2232                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2233                 if (err < 0)
2234                         ret = err;
2235         }
2236         return ret;
2237 }
2238 EXPORT_SYMBOL(generic_file_write);
2239
2240 ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2241                         unsigned long nr_segs, loff_t *ppos)
2242 {
2243         struct kiocb kiocb;
2244         ssize_t ret;
2245
2246         init_sync_kiocb(&kiocb, filp);
2247         ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2248         if (-EIOCBQUEUED == ret)
2249                 ret = wait_on_sync_kiocb(&kiocb);
2250         return ret;
2251 }
2252 EXPORT_SYMBOL(generic_file_readv);
2253
2254 ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2255                         unsigned long nr_segs, loff_t *ppos)
2256 {
2257         struct address_space *mapping = file->f_mapping;
2258         struct inode *inode = mapping->host;
2259         ssize_t ret;
2260
2261         mutex_lock(&inode->i_mutex);
2262         ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2263         mutex_unlock(&inode->i_mutex);
2264
2265         if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2266                 int err;
2267
2268                 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2269                 if (err < 0)
2270                         ret = err;
2271         }
2272         return ret;
2273 }
2274 EXPORT_SYMBOL(generic_file_writev);
2275
2276 /*
2277  * Called under i_mutex for writes to S_ISREG files.   Returns -EIO if something
2278  * went wrong during pagecache shootdown.
2279  */
2280 static ssize_t
2281 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2282         loff_t offset, unsigned long nr_segs)
2283 {
2284         struct file *file = iocb->ki_filp;
2285         struct address_space *mapping = file->f_mapping;
2286         ssize_t retval;
2287         size_t write_len = 0;
2288
2289         /*
2290          * If it's a write, unmap all mmappings of the file up-front.  This
2291          * will cause any pte dirty bits to be propagated into the pageframes
2292          * for the subsequent filemap_write_and_wait().
2293          */
2294         if (rw == WRITE) {
2295                 write_len = iov_length(iov, nr_segs);
2296                 if (mapping_mapped(mapping))
2297                         unmap_mapping_range(mapping, offset, write_len, 0);
2298         }
2299
2300         retval = filemap_write_and_wait(mapping);
2301         if (retval == 0) {
2302                 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2303                                                 offset, nr_segs);
2304                 if (rw == WRITE && mapping->nrpages) {
2305                         pgoff_t end = (offset + write_len - 1)
2306                                                 >> PAGE_CACHE_SHIFT;
2307                         int err = invalidate_inode_pages2_range(mapping,
2308                                         offset >> PAGE_CACHE_SHIFT, end);
2309                         if (err)
2310                                 retval = err;
2311                 }
2312         }
2313         return retval;
2314 }