blob: 3ef20739e7252232c5822cbeed6e22eaa5247d0c [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080018#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#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>
Paul Jackson44110fe2006-03-24 03:16:04 -080032#include <linux/cpuset.h>
Carsten Otteceffc072005-06-23 22:05:25 -070033#include "filemap.h"
Nick Piggin0f8053a2006-03-22 00:08:33 -080034#include "internal.h"
35
Linus Torvalds1da177e2005-04-16 15:20:36 -070036/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 * 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
Adrian Bunk5ce78522005-09-10 00:26:28 -070044static ssize_t
45generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
46 loff_t offset, unsigned long nr_segs);
47
Linus Torvalds1da177e2005-04-16 15:20:36 -070048/*
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)
Hugh Dickins5d337b92005-09-03 15:54:41 -070065 * ->swap_lock (exclusive_swap_page, others)
66 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080068 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 * ->i_mmap_lock (truncate->unmap_mapping_range)
70 *
71 * ->mmap_sem
72 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070073 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
75 *
76 * ->mmap_sem
77 * ->lock_page (access_process_vm)
78 *
79 * ->mmap_sem
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080080 * ->i_mutex (msync)
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080082 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 * ->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
Hugh Dickinsb8072f02005-10-29 18:16:41 -070093 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070095 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070096 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 * ->private_lock (try_to_unmap_one)
98 * ->tree_lock (try_to_unmap_one)
99 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -0800100 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 * ->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 */
116void __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
126void remove_from_page_cache(struct page *page)
127{
128 struct address_space *mapping = page->mapping;
129
Matt Mackallcd7619d2005-05-01 08:59:01 -0700130 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
132 write_lock_irq(&mapping->tree_lock);
133 __remove_from_page_cache(page);
134 write_unlock_irq(&mapping->tree_lock);
135}
136
137static int sync_page(void *word)
138{
139 struct address_space *mapping;
140 struct page *page;
141
Andi Kleen07808b72005-11-05 17:25:53 +0100142 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
144 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700145 * 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
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700160 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700161 * of interest. When page_mapping() does go NULL, the entire
162 * call stack gracefully ignores the page and returns.
163 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 */
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>
Martin Waitz67be2dd2005-05-01 08:59:26 -0700176 * @mapping: address space structure to write
177 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800178 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700179 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 *
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 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800186int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
187 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188{
189 int ret;
190 struct writeback_control wbc = {
191 .sync_mode = sync_mode,
192 .nr_to_write = mapping->nrpages * 2,
193 .start = start,
194 .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
204static inline int __filemap_fdatawrite(struct address_space *mapping,
205 int sync_mode)
206{
207 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
208}
209
210int filemap_fdatawrite(struct address_space *mapping)
211{
212 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
213}
214EXPORT_SYMBOL(filemap_fdatawrite);
215
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800216static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
217 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218{
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 */
226int filemap_flush(struct address_space *mapping)
227{
228 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
229}
230EXPORT_SYMBOL(filemap_flush);
231
232/*
233 * Wait for writeback to complete against pages indexed by start->end
234 * inclusive
235 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800236int wait_on_page_writeback_range(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 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 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800284 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 * it is otherwise livelockable.
286 */
287int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800288 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289{
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) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800298 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800300 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 }
302 if (ret == 0)
303 ret = wait_on_page_writeback_range(mapping, start, end);
304 return ret;
305}
306EXPORT_SYMBOL(sync_page_range);
307
308/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800309 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 * as it forces O_SYNC writers to different parts of the same file
311 * to be serialised right until io completion.
312 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800313int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
314 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315{
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}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800329EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330
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 */
337int 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}
347EXPORT_SYMBOL(filemap_fdatawait);
348
349int filemap_write_and_wait(struct address_space *mapping)
350{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800351 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352
353 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800354 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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800367 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800369EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Andrew Morton469eb4d2006-03-24 03:17:45 -0800371/*
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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377int filemap_write_and_wait_range(struct address_space *mapping,
378 loff_t lstart, loff_t lend)
379{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800380 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800383 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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800394 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395}
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 */
404int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400405 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
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
426EXPORT_SYMBOL(add_to_page_cache);
427
428int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400429 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430{
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
Paul Jackson44110fe2006-03-24 03:16:04 -0800437#ifdef CONFIG_NUMA
438struct 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}
446EXPORT_SYMBOL(page_cache_alloc);
447
448struct 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}
456EXPORT_SYMBOL(page_cache_alloc_cold);
457#endif
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459/*
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 */
469static 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
476static inline void wake_up_page(struct page *page, int bit)
477{
478 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
479}
480
481void 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}
489EXPORT_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 */
506void 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}
514EXPORT_SYMBOL(unlock_page);
515
516/*
517 * End writeback against a page.
518 */
519void 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}
528EXPORT_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 */
538void 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}
545EXPORT_SYMBOL(__lock_page);
546
547/*
548 * a rather lightweight function, finding and getting a reference to a
549 * hashed page atomically.
550 */
551struct 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
563EXPORT_SYMBOL(find_get_page);
564
565/*
566 * Same as above, but trylock it instead of incrementing the count.
567 */
568struct 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
580EXPORT_SYMBOL(find_trylock_page);
581
582/**
583 * find_lock_page - locate, pin and lock a pagecache page
584 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700585 * @mapping: the address_space to search
586 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 *
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 */
593struct 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);
599repeat:
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);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800605 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 read_lock_irq(&mapping->tree_lock);
607
608 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800609 if (unlikely(page->mapping != mapping ||
610 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 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
621EXPORT_SYMBOL(find_lock_page);
622
623/**
624 * find_or_create_page - locate or add a pagecache page
625 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700626 * @mapping: the page's address_space
627 * @index: the page's index into the mapping
628 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 *
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 */
641struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400642 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643{
644 struct page *page, *cached_page = NULL;
645 int err;
646repeat:
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
667EXPORT_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 */
685unsigned 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 * Like find_get_pages, except we only return pages which are tagged with
702 * `tag'. We update *index to index the next page for the traversal.
703 */
704unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
705 int tag, unsigned int nr_pages, struct page **pages)
706{
707 unsigned int i;
708 unsigned int ret;
709
710 read_lock_irq(&mapping->tree_lock);
711 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
712 (void **)pages, *index, nr_pages, tag);
713 for (i = 0; i < ret; i++)
714 page_cache_get(pages[i]);
715 if (ret)
716 *index = pages[ret - 1]->index + 1;
717 read_unlock_irq(&mapping->tree_lock);
718 return ret;
719}
720
721/*
722 * Same as grab_cache_page, but do not wait if the page is unavailable.
723 * This is intended for speculative data generators, where the data can
724 * be regenerated if the page couldn't be grabbed. This routine should
725 * be safe to call while holding the lock for another page.
726 *
727 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
728 * and deadlock against the caller's locked page.
729 */
730struct page *
731grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
732{
733 struct page *page = find_get_page(mapping, index);
Al Viro6daa0e22005-10-21 03:18:50 -0400734 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735
736 if (page) {
737 if (!TestSetPageLocked(page))
738 return page;
739 page_cache_release(page);
740 return NULL;
741 }
742 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
743 page = alloc_pages(gfp_mask, 0);
744 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
745 page_cache_release(page);
746 page = NULL;
747 }
748 return page;
749}
750
751EXPORT_SYMBOL(grab_cache_page_nowait);
752
753/*
754 * This is a generic file read routine, and uses the
755 * mapping->a_ops->readpage() function for the actual low-level
756 * stuff.
757 *
758 * This is really ugly. But the goto's actually try to clarify some
759 * of the logic when it comes to error handling etc.
760 *
761 * Note the struct file* is only passed for the use of readpage. It may be
762 * NULL.
763 */
764void do_generic_mapping_read(struct address_space *mapping,
765 struct file_ra_state *_ra,
766 struct file *filp,
767 loff_t *ppos,
768 read_descriptor_t *desc,
769 read_actor_t actor)
770{
771 struct inode *inode = mapping->host;
772 unsigned long index;
773 unsigned long end_index;
774 unsigned long offset;
775 unsigned long last_index;
776 unsigned long next_index;
777 unsigned long prev_index;
778 loff_t isize;
779 struct page *cached_page;
780 int error;
781 struct file_ra_state ra = *_ra;
782
783 cached_page = NULL;
784 index = *ppos >> PAGE_CACHE_SHIFT;
785 next_index = index;
786 prev_index = ra.prev_page;
787 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
788 offset = *ppos & ~PAGE_CACHE_MASK;
789
790 isize = i_size_read(inode);
791 if (!isize)
792 goto out;
793
794 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
795 for (;;) {
796 struct page *page;
797 unsigned long nr, ret;
798
799 /* nr is the maximum number of bytes to copy from this page */
800 nr = PAGE_CACHE_SIZE;
801 if (index >= end_index) {
802 if (index > end_index)
803 goto out;
804 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
805 if (nr <= offset) {
806 goto out;
807 }
808 }
809 nr = nr - offset;
810
811 cond_resched();
812 if (index == next_index)
813 next_index = page_cache_readahead(mapping, &ra, filp,
814 index, last_index - index);
815
816find_page:
817 page = find_get_page(mapping, index);
818 if (unlikely(page == NULL)) {
819 handle_ra_miss(mapping, &ra, index);
820 goto no_cached_page;
821 }
822 if (!PageUptodate(page))
823 goto page_not_up_to_date;
824page_ok:
825
826 /* If users can be writing to this page using arbitrary
827 * virtual addresses, take care about potential aliasing
828 * before reading the page on the kernel side.
829 */
830 if (mapping_writably_mapped(mapping))
831 flush_dcache_page(page);
832
833 /*
834 * When (part of) the same page is read multiple times
835 * in succession, only mark it as accessed the first time.
836 */
837 if (prev_index != index)
838 mark_page_accessed(page);
839 prev_index = index;
840
841 /*
842 * Ok, we have the page, and it's up-to-date, so
843 * now we can copy it to user space...
844 *
845 * The actor routine returns how many bytes were actually used..
846 * NOTE! This may not be the same as how much of a user buffer
847 * we filled up (we may be padding etc), so we can only update
848 * "pos" here (the actor routine has to update the user buffer
849 * pointers and the remaining count).
850 */
851 ret = actor(desc, page, offset, nr);
852 offset += ret;
853 index += offset >> PAGE_CACHE_SHIFT;
854 offset &= ~PAGE_CACHE_MASK;
855
856 page_cache_release(page);
857 if (ret == nr && desc->count)
858 continue;
859 goto out;
860
861page_not_up_to_date:
862 /* Get exclusive access to the page ... */
863 lock_page(page);
864
865 /* Did it get unhashed before we got the lock? */
866 if (!page->mapping) {
867 unlock_page(page);
868 page_cache_release(page);
869 continue;
870 }
871
872 /* Did somebody else fill it already? */
873 if (PageUptodate(page)) {
874 unlock_page(page);
875 goto page_ok;
876 }
877
878readpage:
879 /* Start the actual read. The read will unlock the page. */
880 error = mapping->a_ops->readpage(filp, page);
881
Zach Brown994fc28c2005-12-15 14:28:17 -0800882 if (unlikely(error)) {
883 if (error == AOP_TRUNCATED_PAGE) {
884 page_cache_release(page);
885 goto find_page;
886 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800888 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889
890 if (!PageUptodate(page)) {
891 lock_page(page);
892 if (!PageUptodate(page)) {
893 if (page->mapping == NULL) {
894 /*
895 * invalidate_inode_pages got it
896 */
897 unlock_page(page);
898 page_cache_release(page);
899 goto find_page;
900 }
901 unlock_page(page);
902 error = -EIO;
903 goto readpage_error;
904 }
905 unlock_page(page);
906 }
907
908 /*
909 * i_size must be checked after we have done ->readpage.
910 *
911 * Checking i_size after the readpage allows us to calculate
912 * the correct value for "nr", which means the zero-filled
913 * part of the page is not copied back to userspace (unless
914 * another truncate extends the file - this is desired though).
915 */
916 isize = i_size_read(inode);
917 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
918 if (unlikely(!isize || index > end_index)) {
919 page_cache_release(page);
920 goto out;
921 }
922
923 /* nr is the maximum number of bytes to copy from this page */
924 nr = PAGE_CACHE_SIZE;
925 if (index == end_index) {
926 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
927 if (nr <= offset) {
928 page_cache_release(page);
929 goto out;
930 }
931 }
932 nr = nr - offset;
933 goto page_ok;
934
935readpage_error:
936 /* UHHUH! A synchronous read error occurred. Report it */
937 desc->error = error;
938 page_cache_release(page);
939 goto out;
940
941no_cached_page:
942 /*
943 * Ok, it wasn't cached, so we need to create a new
944 * page..
945 */
946 if (!cached_page) {
947 cached_page = page_cache_alloc_cold(mapping);
948 if (!cached_page) {
949 desc->error = -ENOMEM;
950 goto out;
951 }
952 }
953 error = add_to_page_cache_lru(cached_page, mapping,
954 index, GFP_KERNEL);
955 if (error) {
956 if (error == -EEXIST)
957 goto find_page;
958 desc->error = error;
959 goto out;
960 }
961 page = cached_page;
962 cached_page = NULL;
963 goto readpage;
964 }
965
966out:
967 *_ra = ra;
968
969 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
970 if (cached_page)
971 page_cache_release(cached_page);
972 if (filp)
973 file_accessed(filp);
974}
975
976EXPORT_SYMBOL(do_generic_mapping_read);
977
978int file_read_actor(read_descriptor_t *desc, struct page *page,
979 unsigned long offset, unsigned long size)
980{
981 char *kaddr;
982 unsigned long left, count = desc->count;
983
984 if (size > count)
985 size = count;
986
987 /*
988 * Faults on the destination of a read are common, so do it before
989 * taking the kmap.
990 */
991 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
992 kaddr = kmap_atomic(page, KM_USER0);
993 left = __copy_to_user_inatomic(desc->arg.buf,
994 kaddr + offset, size);
995 kunmap_atomic(kaddr, KM_USER0);
996 if (left == 0)
997 goto success;
998 }
999
1000 /* Do it the slow way */
1001 kaddr = kmap(page);
1002 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1003 kunmap(page);
1004
1005 if (left) {
1006 size -= left;
1007 desc->error = -EFAULT;
1008 }
1009success:
1010 desc->count = count - size;
1011 desc->written += size;
1012 desc->arg.buf += size;
1013 return size;
1014}
1015
1016/*
1017 * This is the "read()" routine for all filesystems
1018 * that can use the page cache directly.
1019 */
1020ssize_t
1021__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1022 unsigned long nr_segs, loff_t *ppos)
1023{
1024 struct file *filp = iocb->ki_filp;
1025 ssize_t retval;
1026 unsigned long seg;
1027 size_t count;
1028
1029 count = 0;
1030 for (seg = 0; seg < nr_segs; seg++) {
1031 const struct iovec *iv = &iov[seg];
1032
1033 /*
1034 * If any segment has a negative length, or the cumulative
1035 * length ever wraps negative then return -EINVAL.
1036 */
1037 count += iv->iov_len;
1038 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1039 return -EINVAL;
1040 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1041 continue;
1042 if (seg == 0)
1043 return -EFAULT;
1044 nr_segs = seg;
1045 count -= iv->iov_len; /* This segment is no good */
1046 break;
1047 }
1048
1049 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1050 if (filp->f_flags & O_DIRECT) {
1051 loff_t pos = *ppos, size;
1052 struct address_space *mapping;
1053 struct inode *inode;
1054
1055 mapping = filp->f_mapping;
1056 inode = mapping->host;
1057 retval = 0;
1058 if (!count)
1059 goto out; /* skip atime */
1060 size = i_size_read(inode);
1061 if (pos < size) {
1062 retval = generic_file_direct_IO(READ, iocb,
1063 iov, pos, nr_segs);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001064 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 retval = -EIOCBQUEUED;
1066 if (retval > 0)
1067 *ppos = pos + retval;
1068 }
1069 file_accessed(filp);
1070 goto out;
1071 }
1072
1073 retval = 0;
1074 if (count) {
1075 for (seg = 0; seg < nr_segs; seg++) {
1076 read_descriptor_t desc;
1077
1078 desc.written = 0;
1079 desc.arg.buf = iov[seg].iov_base;
1080 desc.count = iov[seg].iov_len;
1081 if (desc.count == 0)
1082 continue;
1083 desc.error = 0;
1084 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1085 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001086 if (desc.error) {
1087 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 break;
1089 }
1090 }
1091 }
1092out:
1093 return retval;
1094}
1095
1096EXPORT_SYMBOL(__generic_file_aio_read);
1097
1098ssize_t
1099generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1100{
1101 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1102
1103 BUG_ON(iocb->ki_pos != pos);
1104 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1105}
1106
1107EXPORT_SYMBOL(generic_file_aio_read);
1108
1109ssize_t
1110generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1111{
1112 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1113 struct kiocb kiocb;
1114 ssize_t ret;
1115
1116 init_sync_kiocb(&kiocb, filp);
1117 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1118 if (-EIOCBQUEUED == ret)
1119 ret = wait_on_sync_kiocb(&kiocb);
1120 return ret;
1121}
1122
1123EXPORT_SYMBOL(generic_file_read);
1124
1125int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1126{
1127 ssize_t written;
1128 unsigned long count = desc->count;
1129 struct file *file = desc->arg.data;
1130
1131 if (size > count)
1132 size = count;
1133
1134 written = file->f_op->sendpage(file, page, offset,
1135 size, &file->f_pos, size<count);
1136 if (written < 0) {
1137 desc->error = written;
1138 written = 0;
1139 }
1140 desc->count = count - written;
1141 desc->written += written;
1142 return written;
1143}
1144
1145ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1146 size_t count, read_actor_t actor, void *target)
1147{
1148 read_descriptor_t desc;
1149
1150 if (!count)
1151 return 0;
1152
1153 desc.written = 0;
1154 desc.count = count;
1155 desc.arg.data = target;
1156 desc.error = 0;
1157
1158 do_generic_file_read(in_file, ppos, &desc, actor);
1159 if (desc.written)
1160 return desc.written;
1161 return desc.error;
1162}
1163
1164EXPORT_SYMBOL(generic_file_sendfile);
1165
1166static ssize_t
1167do_readahead(struct address_space *mapping, struct file *filp,
1168 unsigned long index, unsigned long nr)
1169{
1170 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1171 return -EINVAL;
1172
1173 force_page_cache_readahead(mapping, filp, index,
1174 max_sane_readahead(nr));
1175 return 0;
1176}
1177
1178asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1179{
1180 ssize_t ret;
1181 struct file *file;
1182
1183 ret = -EBADF;
1184 file = fget(fd);
1185 if (file) {
1186 if (file->f_mode & FMODE_READ) {
1187 struct address_space *mapping = file->f_mapping;
1188 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1189 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1190 unsigned long len = end - start + 1;
1191 ret = do_readahead(mapping, file, start, len);
1192 }
1193 fput(file);
1194 }
1195 return ret;
1196}
1197
1198#ifdef CONFIG_MMU
1199/*
1200 * This adds the requested page to the page cache if it isn't already there,
1201 * and schedules an I/O to read in its contents from disk.
1202 */
1203static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1204static int fastcall page_cache_read(struct file * file, unsigned long offset)
1205{
1206 struct address_space *mapping = file->f_mapping;
1207 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001208 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209
Zach Brown994fc28c2005-12-15 14:28:17 -08001210 do {
1211 page = page_cache_alloc_cold(mapping);
1212 if (!page)
1213 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214
Zach Brown994fc28c2005-12-15 14:28:17 -08001215 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1216 if (ret == 0)
1217 ret = mapping->a_ops->readpage(file, page);
1218 else if (ret == -EEXIST)
1219 ret = 0; /* losing race to add is OK */
1220
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222
Zach Brown994fc28c2005-12-15 14:28:17 -08001223 } while (ret == AOP_TRUNCATED_PAGE);
1224
1225 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226}
1227
1228#define MMAP_LOTSAMISS (100)
1229
1230/*
1231 * filemap_nopage() is invoked via the vma operations vector for a
1232 * mapped memory region to read in file data during a page fault.
1233 *
1234 * The goto's are kind of ugly, but this streamlines the normal case of having
1235 * it in the page cache, and handles the special cases reasonably without
1236 * having a lot of duplicated code.
1237 */
1238struct page *filemap_nopage(struct vm_area_struct *area,
1239 unsigned long address, int *type)
1240{
1241 int error;
1242 struct file *file = area->vm_file;
1243 struct address_space *mapping = file->f_mapping;
1244 struct file_ra_state *ra = &file->f_ra;
1245 struct inode *inode = mapping->host;
1246 struct page *page;
1247 unsigned long size, pgoff;
1248 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1249
1250 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1251
1252retry_all:
1253 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1254 if (pgoff >= size)
1255 goto outside_data_content;
1256
1257 /* If we don't want any read-ahead, don't bother */
1258 if (VM_RandomReadHint(area))
1259 goto no_cached_page;
1260
1261 /*
1262 * The readahead code wants to be told about each and every page
1263 * so it can build and shrink its windows appropriately
1264 *
1265 * For sequential accesses, we use the generic readahead logic.
1266 */
1267 if (VM_SequentialReadHint(area))
1268 page_cache_readahead(mapping, ra, file, pgoff, 1);
1269
1270 /*
1271 * Do we have something in the page cache already?
1272 */
1273retry_find:
1274 page = find_get_page(mapping, pgoff);
1275 if (!page) {
1276 unsigned long ra_pages;
1277
1278 if (VM_SequentialReadHint(area)) {
1279 handle_ra_miss(mapping, ra, pgoff);
1280 goto no_cached_page;
1281 }
1282 ra->mmap_miss++;
1283
1284 /*
1285 * Do we miss much more than hit in this file? If so,
1286 * stop bothering with read-ahead. It will only hurt.
1287 */
1288 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1289 goto no_cached_page;
1290
1291 /*
1292 * To keep the pgmajfault counter straight, we need to
1293 * check did_readaround, as this is an inner loop.
1294 */
1295 if (!did_readaround) {
1296 majmin = VM_FAULT_MAJOR;
1297 inc_page_state(pgmajfault);
1298 }
1299 did_readaround = 1;
1300 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1301 if (ra_pages) {
1302 pgoff_t start = 0;
1303
1304 if (pgoff > ra_pages / 2)
1305 start = pgoff - ra_pages / 2;
1306 do_page_cache_readahead(mapping, file, start, ra_pages);
1307 }
1308 page = find_get_page(mapping, pgoff);
1309 if (!page)
1310 goto no_cached_page;
1311 }
1312
1313 if (!did_readaround)
1314 ra->mmap_hit++;
1315
1316 /*
1317 * Ok, found a page in the page cache, now we need to check
1318 * that it's up-to-date.
1319 */
1320 if (!PageUptodate(page))
1321 goto page_not_uptodate;
1322
1323success:
1324 /*
1325 * Found the page and have a reference on it.
1326 */
1327 mark_page_accessed(page);
1328 if (type)
1329 *type = majmin;
1330 return page;
1331
1332outside_data_content:
1333 /*
1334 * An external ptracer can access pages that normally aren't
1335 * accessible..
1336 */
1337 if (area->vm_mm == current->mm)
1338 return NULL;
1339 /* Fall through to the non-read-ahead case */
1340no_cached_page:
1341 /*
1342 * We're only likely to ever get here if MADV_RANDOM is in
1343 * effect.
1344 */
1345 error = page_cache_read(file, pgoff);
1346 grab_swap_token();
1347
1348 /*
1349 * The page we want has now been added to the page cache.
1350 * In the unlikely event that someone removed it in the
1351 * meantime, we'll just come back here and read it again.
1352 */
1353 if (error >= 0)
1354 goto retry_find;
1355
1356 /*
1357 * An error return from page_cache_read can result if the
1358 * system is low on memory, or a problem occurs while trying
1359 * to schedule I/O.
1360 */
1361 if (error == -ENOMEM)
1362 return NOPAGE_OOM;
1363 return NULL;
1364
1365page_not_uptodate:
1366 if (!did_readaround) {
1367 majmin = VM_FAULT_MAJOR;
1368 inc_page_state(pgmajfault);
1369 }
1370 lock_page(page);
1371
1372 /* Did it get unhashed while we waited for it? */
1373 if (!page->mapping) {
1374 unlock_page(page);
1375 page_cache_release(page);
1376 goto retry_all;
1377 }
1378
1379 /* Did somebody else get it up-to-date? */
1380 if (PageUptodate(page)) {
1381 unlock_page(page);
1382 goto success;
1383 }
1384
Zach Brown994fc28c2005-12-15 14:28:17 -08001385 error = mapping->a_ops->readpage(file, page);
1386 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 wait_on_page_locked(page);
1388 if (PageUptodate(page))
1389 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001390 } else if (error == AOP_TRUNCATED_PAGE) {
1391 page_cache_release(page);
1392 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 }
1394
1395 /*
1396 * Umm, take care of errors if the page isn't up-to-date.
1397 * Try to re-read it _once_. We do this synchronously,
1398 * because there really aren't any performance issues here
1399 * and we need to check for errors.
1400 */
1401 lock_page(page);
1402
1403 /* Somebody truncated the page on us? */
1404 if (!page->mapping) {
1405 unlock_page(page);
1406 page_cache_release(page);
1407 goto retry_all;
1408 }
1409
1410 /* Somebody else successfully read it in? */
1411 if (PageUptodate(page)) {
1412 unlock_page(page);
1413 goto success;
1414 }
1415 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001416 error = mapping->a_ops->readpage(file, page);
1417 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 wait_on_page_locked(page);
1419 if (PageUptodate(page))
1420 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001421 } else if (error == AOP_TRUNCATED_PAGE) {
1422 page_cache_release(page);
1423 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 }
1425
1426 /*
1427 * Things didn't work out. Return zero to tell the
1428 * mm layer so, possibly freeing the page cache page first.
1429 */
1430 page_cache_release(page);
1431 return NULL;
1432}
1433
1434EXPORT_SYMBOL(filemap_nopage);
1435
1436static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1437 int nonblock)
1438{
1439 struct address_space *mapping = file->f_mapping;
1440 struct page *page;
1441 int error;
1442
1443 /*
1444 * Do we have something in the page cache already?
1445 */
1446retry_find:
1447 page = find_get_page(mapping, pgoff);
1448 if (!page) {
1449 if (nonblock)
1450 return NULL;
1451 goto no_cached_page;
1452 }
1453
1454 /*
1455 * Ok, found a page in the page cache, now we need to check
1456 * that it's up-to-date.
1457 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001458 if (!PageUptodate(page)) {
1459 if (nonblock) {
1460 page_cache_release(page);
1461 return NULL;
1462 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001464 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465
1466success:
1467 /*
1468 * Found the page and have a reference on it.
1469 */
1470 mark_page_accessed(page);
1471 return page;
1472
1473no_cached_page:
1474 error = page_cache_read(file, pgoff);
1475
1476 /*
1477 * The page we want has now been added to the page cache.
1478 * In the unlikely event that someone removed it in the
1479 * meantime, we'll just come back here and read it again.
1480 */
1481 if (error >= 0)
1482 goto retry_find;
1483
1484 /*
1485 * An error return from page_cache_read can result if the
1486 * system is low on memory, or a problem occurs while trying
1487 * to schedule I/O.
1488 */
1489 return NULL;
1490
1491page_not_uptodate:
1492 lock_page(page);
1493
1494 /* Did it get unhashed while we waited for it? */
1495 if (!page->mapping) {
1496 unlock_page(page);
1497 goto err;
1498 }
1499
1500 /* Did somebody else get it up-to-date? */
1501 if (PageUptodate(page)) {
1502 unlock_page(page);
1503 goto success;
1504 }
1505
Zach Brown994fc28c2005-12-15 14:28:17 -08001506 error = mapping->a_ops->readpage(file, page);
1507 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 wait_on_page_locked(page);
1509 if (PageUptodate(page))
1510 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001511 } else if (error == AOP_TRUNCATED_PAGE) {
1512 page_cache_release(page);
1513 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 }
1515
1516 /*
1517 * Umm, take care of errors if the page isn't up-to-date.
1518 * Try to re-read it _once_. We do this synchronously,
1519 * because there really aren't any performance issues here
1520 * and we need to check for errors.
1521 */
1522 lock_page(page);
1523
1524 /* Somebody truncated the page on us? */
1525 if (!page->mapping) {
1526 unlock_page(page);
1527 goto err;
1528 }
1529 /* Somebody else successfully read it in? */
1530 if (PageUptodate(page)) {
1531 unlock_page(page);
1532 goto success;
1533 }
1534
1535 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001536 error = mapping->a_ops->readpage(file, page);
1537 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 wait_on_page_locked(page);
1539 if (PageUptodate(page))
1540 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001541 } else if (error == AOP_TRUNCATED_PAGE) {
1542 page_cache_release(page);
1543 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544 }
1545
1546 /*
1547 * Things didn't work out. Return zero to tell the
1548 * mm layer so, possibly freeing the page cache page first.
1549 */
1550err:
1551 page_cache_release(page);
1552
1553 return NULL;
1554}
1555
1556int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1557 unsigned long len, pgprot_t prot, unsigned long pgoff,
1558 int nonblock)
1559{
1560 struct file *file = vma->vm_file;
1561 struct address_space *mapping = file->f_mapping;
1562 struct inode *inode = mapping->host;
1563 unsigned long size;
1564 struct mm_struct *mm = vma->vm_mm;
1565 struct page *page;
1566 int err;
1567
1568 if (!nonblock)
1569 force_page_cache_readahead(mapping, vma->vm_file,
1570 pgoff, len >> PAGE_CACHE_SHIFT);
1571
1572repeat:
1573 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1574 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1575 return -EINVAL;
1576
1577 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001578
1579 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1580 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 if (!page && !nonblock)
1582 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001583
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 if (page) {
1585 err = install_page(mm, vma, addr, page, prot);
1586 if (err) {
1587 page_cache_release(page);
1588 return err;
1589 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001590 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001591 /* No page was found just because we can't read it in now (being
1592 * here implies nonblock != 0), but the page may exist, so set
1593 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 err = install_file_pte(mm, vma, addr, pgoff, prot);
1595 if (err)
1596 return err;
1597 }
1598
1599 len -= PAGE_SIZE;
1600 addr += PAGE_SIZE;
1601 pgoff++;
1602 if (len)
1603 goto repeat;
1604
1605 return 0;
1606}
Nikita Danilovb1459462005-10-29 18:17:02 -07001607EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
1609struct vm_operations_struct generic_file_vm_ops = {
1610 .nopage = filemap_nopage,
1611 .populate = filemap_populate,
1612};
1613
1614/* This is used for a general mmap of a disk file */
1615
1616int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1617{
1618 struct address_space *mapping = file->f_mapping;
1619
1620 if (!mapping->a_ops->readpage)
1621 return -ENOEXEC;
1622 file_accessed(file);
1623 vma->vm_ops = &generic_file_vm_ops;
1624 return 0;
1625}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626
1627/*
1628 * This is for filesystems which do not implement ->writepage.
1629 */
1630int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1631{
1632 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1633 return -EINVAL;
1634 return generic_file_mmap(file, vma);
1635}
1636#else
1637int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1638{
1639 return -ENOSYS;
1640}
1641int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1642{
1643 return -ENOSYS;
1644}
1645#endif /* CONFIG_MMU */
1646
1647EXPORT_SYMBOL(generic_file_mmap);
1648EXPORT_SYMBOL(generic_file_readonly_mmap);
1649
1650static inline struct page *__read_cache_page(struct address_space *mapping,
1651 unsigned long index,
1652 int (*filler)(void *,struct page*),
1653 void *data)
1654{
1655 struct page *page, *cached_page = NULL;
1656 int err;
1657repeat:
1658 page = find_get_page(mapping, index);
1659 if (!page) {
1660 if (!cached_page) {
1661 cached_page = page_cache_alloc_cold(mapping);
1662 if (!cached_page)
1663 return ERR_PTR(-ENOMEM);
1664 }
1665 err = add_to_page_cache_lru(cached_page, mapping,
1666 index, GFP_KERNEL);
1667 if (err == -EEXIST)
1668 goto repeat;
1669 if (err < 0) {
1670 /* Presumably ENOMEM for radix tree node */
1671 page_cache_release(cached_page);
1672 return ERR_PTR(err);
1673 }
1674 page = cached_page;
1675 cached_page = NULL;
1676 err = filler(data, page);
1677 if (err < 0) {
1678 page_cache_release(page);
1679 page = ERR_PTR(err);
1680 }
1681 }
1682 if (cached_page)
1683 page_cache_release(cached_page);
1684 return page;
1685}
1686
1687/*
1688 * Read into the page cache. If a page already exists,
1689 * and PageUptodate() is not set, try to fill the page.
1690 */
1691struct page *read_cache_page(struct address_space *mapping,
1692 unsigned long index,
1693 int (*filler)(void *,struct page*),
1694 void *data)
1695{
1696 struct page *page;
1697 int err;
1698
1699retry:
1700 page = __read_cache_page(mapping, index, filler, data);
1701 if (IS_ERR(page))
1702 goto out;
1703 mark_page_accessed(page);
1704 if (PageUptodate(page))
1705 goto out;
1706
1707 lock_page(page);
1708 if (!page->mapping) {
1709 unlock_page(page);
1710 page_cache_release(page);
1711 goto retry;
1712 }
1713 if (PageUptodate(page)) {
1714 unlock_page(page);
1715 goto out;
1716 }
1717 err = filler(data, page);
1718 if (err < 0) {
1719 page_cache_release(page);
1720 page = ERR_PTR(err);
1721 }
1722 out:
1723 return page;
1724}
1725
1726EXPORT_SYMBOL(read_cache_page);
1727
1728/*
1729 * If the page was newly created, increment its refcount and add it to the
1730 * caller's lru-buffering pagevec. This function is specifically for
1731 * generic_file_write().
1732 */
1733static inline struct page *
1734__grab_cache_page(struct address_space *mapping, unsigned long index,
1735 struct page **cached_page, struct pagevec *lru_pvec)
1736{
1737 int err;
1738 struct page *page;
1739repeat:
1740 page = find_lock_page(mapping, index);
1741 if (!page) {
1742 if (!*cached_page) {
1743 *cached_page = page_cache_alloc(mapping);
1744 if (!*cached_page)
1745 return NULL;
1746 }
1747 err = add_to_page_cache(*cached_page, mapping,
1748 index, GFP_KERNEL);
1749 if (err == -EEXIST)
1750 goto repeat;
1751 if (err == 0) {
1752 page = *cached_page;
1753 page_cache_get(page);
1754 if (!pagevec_add(lru_pvec, page))
1755 __pagevec_lru_add(lru_pvec);
1756 *cached_page = NULL;
1757 }
1758 }
1759 return page;
1760}
1761
1762/*
1763 * The logic we want is
1764 *
1765 * if suid or (sgid and xgrp)
1766 * remove privs
1767 */
1768int remove_suid(struct dentry *dentry)
1769{
1770 mode_t mode = dentry->d_inode->i_mode;
1771 int kill = 0;
1772 int result = 0;
1773
1774 /* suid always must be killed */
1775 if (unlikely(mode & S_ISUID))
1776 kill = ATTR_KILL_SUID;
1777
1778 /*
1779 * sgid without any exec bits is just a mandatory locking mark; leave
1780 * it alone. If some exec bits are set, it's a real sgid; kill it.
1781 */
1782 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1783 kill |= ATTR_KILL_SGID;
1784
1785 if (unlikely(kill && !capable(CAP_FSETID))) {
1786 struct iattr newattrs;
1787
1788 newattrs.ia_valid = ATTR_FORCE | kill;
1789 result = notify_change(dentry, &newattrs);
1790 }
1791 return result;
1792}
1793EXPORT_SYMBOL(remove_suid);
1794
Carsten Otteceffc072005-06-23 22:05:25 -07001795size_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796__filemap_copy_from_user_iovec(char *vaddr,
1797 const struct iovec *iov, size_t base, size_t bytes)
1798{
1799 size_t copied = 0, left = 0;
1800
1801 while (bytes) {
1802 char __user *buf = iov->iov_base + base;
1803 int copy = min(bytes, iov->iov_len - base);
1804
1805 base = 0;
1806 left = __copy_from_user_inatomic(vaddr, buf, copy);
1807 copied += copy;
1808 bytes -= copy;
1809 vaddr += copy;
1810 iov++;
1811
1812 if (unlikely(left)) {
1813 /* zero the rest of the target like __copy_from_user */
1814 if (bytes)
1815 memset(vaddr, 0, bytes);
1816 break;
1817 }
1818 }
1819 return copied - left;
1820}
1821
1822/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 * Performs necessary checks before doing a write
1824 *
1825 * Can adjust writing position aor amount of bytes to write.
1826 * Returns appropriate error code that caller should return or
1827 * zero in case that write should be allowed.
1828 */
1829inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1830{
1831 struct inode *inode = file->f_mapping->host;
1832 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1833
1834 if (unlikely(*pos < 0))
1835 return -EINVAL;
1836
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837 if (!isblk) {
1838 /* FIXME: this is for backwards compatibility with 2.4 */
1839 if (file->f_flags & O_APPEND)
1840 *pos = i_size_read(inode);
1841
1842 if (limit != RLIM_INFINITY) {
1843 if (*pos >= limit) {
1844 send_sig(SIGXFSZ, current, 0);
1845 return -EFBIG;
1846 }
1847 if (*count > limit - (typeof(limit))*pos) {
1848 *count = limit - (typeof(limit))*pos;
1849 }
1850 }
1851 }
1852
1853 /*
1854 * LFS rule
1855 */
1856 if (unlikely(*pos + *count > MAX_NON_LFS &&
1857 !(file->f_flags & O_LARGEFILE))) {
1858 if (*pos >= MAX_NON_LFS) {
1859 send_sig(SIGXFSZ, current, 0);
1860 return -EFBIG;
1861 }
1862 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1863 *count = MAX_NON_LFS - (unsigned long)*pos;
1864 }
1865 }
1866
1867 /*
1868 * Are we about to exceed the fs block limit ?
1869 *
1870 * If we have written data it becomes a short write. If we have
1871 * exceeded without writing data we send a signal and return EFBIG.
1872 * Linus frestrict idea will clean these up nicely..
1873 */
1874 if (likely(!isblk)) {
1875 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1876 if (*count || *pos > inode->i_sb->s_maxbytes) {
1877 send_sig(SIGXFSZ, current, 0);
1878 return -EFBIG;
1879 }
1880 /* zero-length writes at ->s_maxbytes are OK */
1881 }
1882
1883 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1884 *count = inode->i_sb->s_maxbytes - *pos;
1885 } else {
1886 loff_t isize;
1887 if (bdev_read_only(I_BDEV(inode)))
1888 return -EPERM;
1889 isize = i_size_read(inode);
1890 if (*pos >= isize) {
1891 if (*count || *pos > isize)
1892 return -ENOSPC;
1893 }
1894
1895 if (*pos + *count > isize)
1896 *count = isize - *pos;
1897 }
1898 return 0;
1899}
1900EXPORT_SYMBOL(generic_write_checks);
1901
1902ssize_t
1903generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1904 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1905 size_t count, size_t ocount)
1906{
1907 struct file *file = iocb->ki_filp;
1908 struct address_space *mapping = file->f_mapping;
1909 struct inode *inode = mapping->host;
1910 ssize_t written;
1911
1912 if (count != ocount)
1913 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1914
1915 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1916 if (written > 0) {
1917 loff_t end = pos + written;
1918 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1919 i_size_write(inode, end);
1920 mark_inode_dirty(inode);
1921 }
1922 *ppos = end;
1923 }
1924
1925 /*
1926 * Sync the fs metadata but not the minor inode changes and
1927 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001928 * i_mutex is held, which protects generic_osync_inode() from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 * livelocking.
1930 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07001931 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1932 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1933 if (err < 0)
1934 written = err;
1935 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936 if (written == count && !is_sync_kiocb(iocb))
1937 written = -EIOCBQUEUED;
1938 return written;
1939}
1940EXPORT_SYMBOL(generic_file_direct_write);
1941
1942ssize_t
1943generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1944 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1945 size_t count, ssize_t written)
1946{
1947 struct file *file = iocb->ki_filp;
1948 struct address_space * mapping = file->f_mapping;
1949 struct address_space_operations *a_ops = mapping->a_ops;
1950 struct inode *inode = mapping->host;
1951 long status = 0;
1952 struct page *page;
1953 struct page *cached_page = NULL;
1954 size_t bytes;
1955 struct pagevec lru_pvec;
1956 const struct iovec *cur_iov = iov; /* current iovec */
1957 size_t iov_base = 0; /* offset in the current iovec */
1958 char __user *buf;
1959
1960 pagevec_init(&lru_pvec, 0);
1961
1962 /*
1963 * handle partial DIO write. Adjust cur_iov if needed.
1964 */
1965 if (likely(nr_segs == 1))
1966 buf = iov->iov_base + written;
1967 else {
1968 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001969 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970 }
1971
1972 do {
1973 unsigned long index;
1974 unsigned long offset;
Martin Schwidefskya5117182005-06-06 13:35:54 -07001975 unsigned long maxlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976 size_t copied;
1977
1978 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1979 index = pos >> PAGE_CACHE_SHIFT;
1980 bytes = PAGE_CACHE_SIZE - offset;
1981 if (bytes > count)
1982 bytes = count;
1983
1984 /*
1985 * Bring in the user page that we will copy from _first_.
1986 * Otherwise there's a nasty deadlock on copying from the
1987 * same page as we're writing to, without it being marked
1988 * up-to-date.
1989 */
Martin Schwidefskya5117182005-06-06 13:35:54 -07001990 maxlen = cur_iov->iov_len - iov_base;
1991 if (maxlen > bytes)
1992 maxlen = bytes;
1993 fault_in_pages_readable(buf, maxlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994
1995 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1996 if (!page) {
1997 status = -ENOMEM;
1998 break;
1999 }
2000
2001 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2002 if (unlikely(status)) {
2003 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08002004
2005 if (status != AOP_TRUNCATED_PAGE)
2006 unlock_page(page);
2007 page_cache_release(page);
2008 if (status == AOP_TRUNCATED_PAGE)
2009 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 /*
2011 * prepare_write() may have instantiated a few blocks
2012 * outside i_size. Trim these off again.
2013 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014 if (pos + bytes > isize)
2015 vmtruncate(inode, isize);
2016 break;
2017 }
2018 if (likely(nr_segs == 1))
2019 copied = filemap_copy_from_user(page, offset,
2020 buf, bytes);
2021 else
2022 copied = filemap_copy_from_user_iovec(page, offset,
2023 cur_iov, iov_base, bytes);
2024 flush_dcache_page(page);
2025 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08002026 if (status == AOP_TRUNCATED_PAGE) {
2027 page_cache_release(page);
2028 continue;
2029 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 if (likely(copied > 0)) {
2031 if (!status)
2032 status = copied;
2033
2034 if (status >= 0) {
2035 written += status;
2036 count -= status;
2037 pos += status;
2038 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002039 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040 filemap_set_next_iovec(&cur_iov,
2041 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002042 if (count)
2043 buf = cur_iov->iov_base +
2044 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002045 } else {
2046 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002047 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048 }
2049 }
2050 if (unlikely(copied != bytes))
2051 if (status >= 0)
2052 status = -EFAULT;
2053 unlock_page(page);
2054 mark_page_accessed(page);
2055 page_cache_release(page);
2056 if (status < 0)
2057 break;
2058 balance_dirty_pages_ratelimited(mapping);
2059 cond_resched();
2060 } while (count);
2061 *ppos = pos;
2062
2063 if (cached_page)
2064 page_cache_release(cached_page);
2065
2066 /*
2067 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2068 */
2069 if (likely(status >= 0)) {
2070 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2071 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2072 status = generic_osync_inode(inode, mapping,
2073 OSYNC_METADATA|OSYNC_DATA);
2074 }
2075 }
2076
2077 /*
2078 * If we get here for O_DIRECT writes then we must have fallen through
2079 * to buffered writes (block instantiation inside i_size). So we sync
2080 * the file data here, to try to honour O_DIRECT expectations.
2081 */
2082 if (unlikely(file->f_flags & O_DIRECT) && written)
2083 status = filemap_write_and_wait(mapping);
2084
2085 pagevec_lru_add(&lru_pvec);
2086 return written ? written : status;
2087}
2088EXPORT_SYMBOL(generic_file_buffered_write);
2089
Adrian Bunk5ce78522005-09-10 00:26:28 -07002090static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2092 unsigned long nr_segs, loff_t *ppos)
2093{
2094 struct file *file = iocb->ki_filp;
2095 struct address_space * mapping = file->f_mapping;
2096 size_t ocount; /* original count */
2097 size_t count; /* after file limit checks */
2098 struct inode *inode = mapping->host;
2099 unsigned long seg;
2100 loff_t pos;
2101 ssize_t written;
2102 ssize_t err;
2103
2104 ocount = 0;
2105 for (seg = 0; seg < nr_segs; seg++) {
2106 const struct iovec *iv = &iov[seg];
2107
2108 /*
2109 * If any segment has a negative length, or the cumulative
2110 * length ever wraps negative then return -EINVAL.
2111 */
2112 ocount += iv->iov_len;
2113 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2114 return -EINVAL;
2115 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2116 continue;
2117 if (seg == 0)
2118 return -EFAULT;
2119 nr_segs = seg;
2120 ocount -= iv->iov_len; /* This segment is no good */
2121 break;
2122 }
2123
2124 count = ocount;
2125 pos = *ppos;
2126
2127 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2128
2129 /* We can write back this queue in page reclaim */
2130 current->backing_dev_info = mapping->backing_dev_info;
2131 written = 0;
2132
2133 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2134 if (err)
2135 goto out;
2136
2137 if (count == 0)
2138 goto out;
2139
2140 err = remove_suid(file->f_dentry);
2141 if (err)
2142 goto out;
2143
Christoph Hellwig870f4812006-01-09 20:52:01 -08002144 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145
2146 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2147 if (unlikely(file->f_flags & O_DIRECT)) {
2148 written = generic_file_direct_write(iocb, iov,
2149 &nr_segs, pos, ppos, count, ocount);
2150 if (written < 0 || written == count)
2151 goto out;
2152 /*
2153 * direct-io write to a hole: fall through to buffered I/O
2154 * for completing the rest of the request.
2155 */
2156 pos += written;
2157 count -= written;
2158 }
2159
2160 written = generic_file_buffered_write(iocb, iov, nr_segs,
2161 pos, ppos, count, written);
2162out:
2163 current->backing_dev_info = NULL;
2164 return written ? written : err;
2165}
2166EXPORT_SYMBOL(generic_file_aio_write_nolock);
2167
2168ssize_t
2169generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2170 unsigned long nr_segs, loff_t *ppos)
2171{
2172 struct file *file = iocb->ki_filp;
2173 struct address_space *mapping = file->f_mapping;
2174 struct inode *inode = mapping->host;
2175 ssize_t ret;
2176 loff_t pos = *ppos;
2177
2178 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2179
2180 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2181 int err;
2182
2183 err = sync_page_range_nolock(inode, mapping, pos, ret);
2184 if (err < 0)
2185 ret = err;
2186 }
2187 return ret;
2188}
2189
Adrian Bunk5ce78522005-09-10 00:26:28 -07002190static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2192 unsigned long nr_segs, loff_t *ppos)
2193{
2194 struct kiocb kiocb;
2195 ssize_t ret;
2196
2197 init_sync_kiocb(&kiocb, file);
2198 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2199 if (ret == -EIOCBQUEUED)
2200 ret = wait_on_sync_kiocb(&kiocb);
2201 return ret;
2202}
2203
2204ssize_t
2205generic_file_write_nolock(struct file *file, const struct iovec *iov,
2206 unsigned long nr_segs, loff_t *ppos)
2207{
2208 struct kiocb kiocb;
2209 ssize_t ret;
2210
2211 init_sync_kiocb(&kiocb, file);
2212 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2213 if (-EIOCBQUEUED == ret)
2214 ret = wait_on_sync_kiocb(&kiocb);
2215 return ret;
2216}
2217EXPORT_SYMBOL(generic_file_write_nolock);
2218
2219ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2220 size_t count, loff_t pos)
2221{
2222 struct file *file = iocb->ki_filp;
2223 struct address_space *mapping = file->f_mapping;
2224 struct inode *inode = mapping->host;
2225 ssize_t ret;
2226 struct iovec local_iov = { .iov_base = (void __user *)buf,
2227 .iov_len = count };
2228
2229 BUG_ON(iocb->ki_pos != pos);
2230
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002231 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2233 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002234 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235
2236 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2237 ssize_t err;
2238
2239 err = sync_page_range(inode, mapping, pos, ret);
2240 if (err < 0)
2241 ret = err;
2242 }
2243 return ret;
2244}
2245EXPORT_SYMBOL(generic_file_aio_write);
2246
2247ssize_t generic_file_write(struct file *file, const char __user *buf,
2248 size_t count, loff_t *ppos)
2249{
2250 struct address_space *mapping = file->f_mapping;
2251 struct inode *inode = mapping->host;
2252 ssize_t ret;
2253 struct iovec local_iov = { .iov_base = (void __user *)buf,
2254 .iov_len = count };
2255
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002256 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002258 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259
2260 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2261 ssize_t err;
2262
2263 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2264 if (err < 0)
2265 ret = err;
2266 }
2267 return ret;
2268}
2269EXPORT_SYMBOL(generic_file_write);
2270
2271ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2272 unsigned long nr_segs, loff_t *ppos)
2273{
2274 struct kiocb kiocb;
2275 ssize_t ret;
2276
2277 init_sync_kiocb(&kiocb, filp);
2278 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2279 if (-EIOCBQUEUED == ret)
2280 ret = wait_on_sync_kiocb(&kiocb);
2281 return ret;
2282}
2283EXPORT_SYMBOL(generic_file_readv);
2284
2285ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2286 unsigned long nr_segs, loff_t *ppos)
2287{
2288 struct address_space *mapping = file->f_mapping;
2289 struct inode *inode = mapping->host;
2290 ssize_t ret;
2291
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002292 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002293 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002294 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295
2296 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2297 int err;
2298
2299 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2300 if (err < 0)
2301 ret = err;
2302 }
2303 return ret;
2304}
2305EXPORT_SYMBOL(generic_file_writev);
2306
2307/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002308 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002309 * went wrong during pagecache shootdown.
2310 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002311static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2313 loff_t offset, unsigned long nr_segs)
2314{
2315 struct file *file = iocb->ki_filp;
2316 struct address_space *mapping = file->f_mapping;
2317 ssize_t retval;
2318 size_t write_len = 0;
2319
2320 /*
2321 * If it's a write, unmap all mmappings of the file up-front. This
2322 * will cause any pte dirty bits to be propagated into the pageframes
2323 * for the subsequent filemap_write_and_wait().
2324 */
2325 if (rw == WRITE) {
2326 write_len = iov_length(iov, nr_segs);
2327 if (mapping_mapped(mapping))
2328 unmap_mapping_range(mapping, offset, write_len, 0);
2329 }
2330
2331 retval = filemap_write_and_wait(mapping);
2332 if (retval == 0) {
2333 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2334 offset, nr_segs);
2335 if (rw == WRITE && mapping->nrpages) {
2336 pgoff_t end = (offset + write_len - 1)
2337 >> PAGE_CACHE_SHIFT;
2338 int err = invalidate_inode_pages2_range(mapping,
2339 offset >> PAGE_CACHE_SHIFT, end);
2340 if (err)
2341 retval = err;
2342 }
2343 }
2344 return retval;
2345}