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