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1 | /* |
2 | * This file is part of UBIFS. | |
3 | * | |
4 | * Copyright (C) 2006-2008 Nokia Corporation. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License version 2 as published by | |
8 | * the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
11 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
12 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
13 | * more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License along with | |
16 | * this program; if not, write to the Free Software Foundation, Inc., 51 | |
17 | * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
18 | * | |
19 | * Authors: Artem Bityutskiy (Битюцкий Артём) | |
20 | * Adrian Hunter | |
21 | */ | |
22 | ||
23 | /* | |
24 | * This file implements VFS file and inode operations of regular files, device | |
25 | * nodes and symlinks as well as address space operations. | |
26 | * | |
27 | * UBIFS uses 2 page flags: PG_private and PG_checked. PG_private is set if the | |
28 | * page is dirty and is used for budgeting purposes - dirty pages should not be | |
29 | * budgeted. The PG_checked flag is set if full budgeting is required for the | |
30 | * page e.g., when it corresponds to a file hole or it is just beyond the file | |
31 | * size. The budgeting is done in 'ubifs_write_begin()', because it is OK to | |
32 | * fail in this function, and the budget is released in 'ubifs_write_end()'. So | |
33 | * the PG_private and PG_checked flags carry the information about how the page | |
34 | * was budgeted, to make it possible to release the budget properly. | |
35 | * | |
36 | * A thing to keep in mind: inode's 'i_mutex' is locked in most VFS operations | |
37 | * we implement. However, this is not true for '->writepage()', which might be | |
38 | * called with 'i_mutex' unlocked. For example, when pdflush is performing | |
39 | * write-back, it calls 'writepage()' with unlocked 'i_mutex', although the | |
40 | * inode has 'I_LOCK' flag in this case. At "normal" work-paths 'i_mutex' is | |
41 | * locked in '->writepage', e.g. in "sys_write -> alloc_pages -> direct reclaim | |
42 | * path'. So, in '->writepage()' we are only guaranteed that the page is | |
43 | * locked. | |
44 | * | |
45 | * Similarly, 'i_mutex' does not have to be locked in readpage(), e.g., | |
46 | * readahead path does not have it locked ("sys_read -> generic_file_aio_read | |
47 | * -> ondemand_readahead -> readpage"). In case of readahead, 'I_LOCK' flag is | |
48 | * not set as well. However, UBIFS disables readahead. | |
49 | * | |
50 | * This, for example means that there might be 2 concurrent '->writepage()' | |
51 | * calls for the same inode, but different inode dirty pages. | |
52 | */ | |
53 | ||
54 | #include "ubifs.h" | |
55 | #include <linux/mount.h> | |
56 | ||
57 | static int read_block(struct inode *inode, void *addr, unsigned int block, | |
58 | struct ubifs_data_node *dn) | |
59 | { | |
60 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
61 | int err, len, out_len; | |
62 | union ubifs_key key; | |
63 | unsigned int dlen; | |
64 | ||
65 | data_key_init(c, &key, inode->i_ino, block); | |
66 | err = ubifs_tnc_lookup(c, &key, dn); | |
67 | if (err) { | |
68 | if (err == -ENOENT) | |
69 | /* Not found, so it must be a hole */ | |
70 | memset(addr, 0, UBIFS_BLOCK_SIZE); | |
71 | return err; | |
72 | } | |
73 | ||
74 | ubifs_assert(dn->ch.sqnum > ubifs_inode(inode)->creat_sqnum); | |
75 | ||
76 | len = le32_to_cpu(dn->size); | |
77 | if (len <= 0 || len > UBIFS_BLOCK_SIZE) | |
78 | goto dump; | |
79 | ||
80 | dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ; | |
81 | out_len = UBIFS_BLOCK_SIZE; | |
82 | err = ubifs_decompress(&dn->data, dlen, addr, &out_len, | |
83 | le16_to_cpu(dn->compr_type)); | |
84 | if (err || len != out_len) | |
85 | goto dump; | |
86 | ||
87 | /* | |
88 | * Data length can be less than a full block, even for blocks that are | |
89 | * not the last in the file (e.g., as a result of making a hole and | |
90 | * appending data). Ensure that the remainder is zeroed out. | |
91 | */ | |
92 | if (len < UBIFS_BLOCK_SIZE) | |
93 | memset(addr + len, 0, UBIFS_BLOCK_SIZE - len); | |
94 | ||
95 | return 0; | |
96 | ||
97 | dump: | |
98 | ubifs_err("bad data node (block %u, inode %lu)", | |
99 | block, inode->i_ino); | |
100 | dbg_dump_node(c, dn); | |
101 | return -EINVAL; | |
102 | } | |
103 | ||
104 | static int do_readpage(struct page *page) | |
105 | { | |
106 | void *addr; | |
107 | int err = 0, i; | |
108 | unsigned int block, beyond; | |
109 | struct ubifs_data_node *dn; | |
110 | struct inode *inode = page->mapping->host; | |
111 | loff_t i_size = i_size_read(inode); | |
112 | ||
113 | dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx", | |
114 | inode->i_ino, page->index, i_size, page->flags); | |
115 | ubifs_assert(!PageChecked(page)); | |
116 | ubifs_assert(!PagePrivate(page)); | |
117 | ||
118 | addr = kmap(page); | |
119 | ||
120 | block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; | |
121 | beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT; | |
122 | if (block >= beyond) { | |
123 | /* Reading beyond inode */ | |
124 | SetPageChecked(page); | |
125 | memset(addr, 0, PAGE_CACHE_SIZE); | |
126 | goto out; | |
127 | } | |
128 | ||
129 | dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS); | |
130 | if (!dn) { | |
131 | err = -ENOMEM; | |
132 | goto error; | |
133 | } | |
134 | ||
135 | i = 0; | |
136 | while (1) { | |
137 | int ret; | |
138 | ||
139 | if (block >= beyond) { | |
140 | /* Reading beyond inode */ | |
141 | err = -ENOENT; | |
142 | memset(addr, 0, UBIFS_BLOCK_SIZE); | |
143 | } else { | |
144 | ret = read_block(inode, addr, block, dn); | |
145 | if (ret) { | |
146 | err = ret; | |
147 | if (err != -ENOENT) | |
148 | break; | |
149 | } | |
150 | } | |
151 | if (++i >= UBIFS_BLOCKS_PER_PAGE) | |
152 | break; | |
153 | block += 1; | |
154 | addr += UBIFS_BLOCK_SIZE; | |
155 | } | |
156 | if (err) { | |
157 | if (err == -ENOENT) { | |
158 | /* Not found, so it must be a hole */ | |
159 | SetPageChecked(page); | |
160 | dbg_gen("hole"); | |
161 | goto out_free; | |
162 | } | |
163 | ubifs_err("cannot read page %lu of inode %lu, error %d", | |
164 | page->index, inode->i_ino, err); | |
165 | goto error; | |
166 | } | |
167 | ||
168 | out_free: | |
169 | kfree(dn); | |
170 | out: | |
171 | SetPageUptodate(page); | |
172 | ClearPageError(page); | |
173 | flush_dcache_page(page); | |
174 | kunmap(page); | |
175 | return 0; | |
176 | ||
177 | error: | |
178 | kfree(dn); | |
179 | ClearPageUptodate(page); | |
180 | SetPageError(page); | |
181 | flush_dcache_page(page); | |
182 | kunmap(page); | |
183 | return err; | |
184 | } | |
185 | ||
186 | /** | |
187 | * release_new_page_budget - release budget of a new page. | |
188 | * @c: UBIFS file-system description object | |
189 | * | |
190 | * This is a helper function which releases budget corresponding to the budget | |
191 | * of one new page of data. | |
192 | */ | |
193 | static void release_new_page_budget(struct ubifs_info *c) | |
194 | { | |
195 | struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 }; | |
196 | ||
197 | ubifs_release_budget(c, &req); | |
198 | } | |
199 | ||
200 | /** | |
201 | * release_existing_page_budget - release budget of an existing page. | |
202 | * @c: UBIFS file-system description object | |
203 | * | |
204 | * This is a helper function which releases budget corresponding to the budget | |
205 | * of changing one one page of data which already exists on the flash media. | |
206 | */ | |
207 | static void release_existing_page_budget(struct ubifs_info *c) | |
208 | { | |
209 | struct ubifs_budget_req req = { .dd_growth = c->page_budget}; | |
210 | ||
211 | ubifs_release_budget(c, &req); | |
212 | } | |
213 | ||
214 | static int write_begin_slow(struct address_space *mapping, | |
215 | loff_t pos, unsigned len, struct page **pagep) | |
216 | { | |
217 | struct inode *inode = mapping->host; | |
218 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
219 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
220 | struct ubifs_budget_req req = { .new_page = 1 }; | |
221 | int uninitialized_var(err), appending = !!(pos + len > inode->i_size); | |
222 | struct page *page; | |
223 | ||
224 | dbg_gen("ino %lu, pos %llu, len %u, i_size %lld", | |
225 | inode->i_ino, pos, len, inode->i_size); | |
226 | ||
227 | /* | |
228 | * At the slow path we have to budget before locking the page, because | |
229 | * budgeting may force write-back, which would wait on locked pages and | |
230 | * deadlock if we had the page locked. At this point we do not know | |
231 | * anything about the page, so assume that this is a new page which is | |
232 | * written to a hole. This corresponds to largest budget. Later the | |
233 | * budget will be amended if this is not true. | |
234 | */ | |
235 | if (appending) | |
236 | /* We are appending data, budget for inode change */ | |
237 | req.dirtied_ino = 1; | |
238 | ||
239 | err = ubifs_budget_space(c, &req); | |
240 | if (unlikely(err)) | |
241 | return err; | |
242 | ||
243 | page = __grab_cache_page(mapping, index); | |
244 | if (unlikely(!page)) { | |
245 | ubifs_release_budget(c, &req); | |
246 | return -ENOMEM; | |
247 | } | |
248 | ||
249 | if (!PageUptodate(page)) { | |
250 | if (!(pos & PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) | |
251 | SetPageChecked(page); | |
252 | else { | |
253 | err = do_readpage(page); | |
254 | if (err) { | |
255 | unlock_page(page); | |
256 | page_cache_release(page); | |
257 | return err; | |
258 | } | |
259 | } | |
260 | ||
261 | SetPageUptodate(page); | |
262 | ClearPageError(page); | |
263 | } | |
264 | ||
265 | if (PagePrivate(page)) | |
266 | /* | |
267 | * The page is dirty, which means it was budgeted twice: | |
268 | * o first time the budget was allocated by the task which | |
269 | * made the page dirty and set the PG_private flag; | |
270 | * o and then we budgeted for it for the second time at the | |
271 | * very beginning of this function. | |
272 | * | |
273 | * So what we have to do is to release the page budget we | |
274 | * allocated. | |
275 | */ | |
276 | release_new_page_budget(c); | |
277 | else if (!PageChecked(page)) | |
278 | /* | |
279 | * We are changing a page which already exists on the media. | |
280 | * This means that changing the page does not make the amount | |
281 | * of indexing information larger, and this part of the budget | |
282 | * which we have already acquired may be released. | |
283 | */ | |
284 | ubifs_convert_page_budget(c); | |
285 | ||
286 | if (appending) { | |
287 | struct ubifs_inode *ui = ubifs_inode(inode); | |
288 | ||
289 | /* | |
290 | * 'ubifs_write_end()' is optimized from the fast-path part of | |
291 | * 'ubifs_write_begin()' and expects the @ui_mutex to be locked | |
292 | * if data is appended. | |
293 | */ | |
294 | mutex_lock(&ui->ui_mutex); | |
295 | if (ui->dirty) | |
296 | /* | |
297 | * The inode is dirty already, so we may free the | |
298 | * budget we allocated. | |
299 | */ | |
300 | ubifs_release_dirty_inode_budget(c, ui); | |
301 | } | |
302 | ||
303 | *pagep = page; | |
304 | return 0; | |
305 | } | |
306 | ||
307 | /** | |
308 | * allocate_budget - allocate budget for 'ubifs_write_begin()'. | |
309 | * @c: UBIFS file-system description object | |
310 | * @page: page to allocate budget for | |
311 | * @ui: UBIFS inode object the page belongs to | |
312 | * @appending: non-zero if the page is appended | |
313 | * | |
314 | * This is a helper function for 'ubifs_write_begin()' which allocates budget | |
315 | * for the operation. The budget is allocated differently depending on whether | |
316 | * this is appending, whether the page is dirty or not, and so on. This | |
317 | * function leaves the @ui->ui_mutex locked in case of appending. Returns zero | |
318 | * in case of success and %-ENOSPC in case of failure. | |
319 | */ | |
320 | static int allocate_budget(struct ubifs_info *c, struct page *page, | |
321 | struct ubifs_inode *ui, int appending) | |
322 | { | |
323 | struct ubifs_budget_req req = { .fast = 1 }; | |
324 | ||
325 | if (PagePrivate(page)) { | |
326 | if (!appending) | |
327 | /* | |
328 | * The page is dirty and we are not appending, which | |
329 | * means no budget is needed at all. | |
330 | */ | |
331 | return 0; | |
332 | ||
333 | mutex_lock(&ui->ui_mutex); | |
334 | if (ui->dirty) | |
335 | /* | |
336 | * The page is dirty and we are appending, so the inode | |
337 | * has to be marked as dirty. However, it is already | |
338 | * dirty, so we do not need any budget. We may return, | |
339 | * but @ui->ui_mutex hast to be left locked because we | |
340 | * should prevent write-back from flushing the inode | |
341 | * and freeing the budget. The lock will be released in | |
342 | * 'ubifs_write_end()'. | |
343 | */ | |
344 | return 0; | |
345 | ||
346 | /* | |
347 | * The page is dirty, we are appending, the inode is clean, so | |
348 | * we need to budget the inode change. | |
349 | */ | |
350 | req.dirtied_ino = 1; | |
351 | } else { | |
352 | if (PageChecked(page)) | |
353 | /* | |
354 | * The page corresponds to a hole and does not | |
355 | * exist on the media. So changing it makes | |
356 | * make the amount of indexing information | |
357 | * larger, and we have to budget for a new | |
358 | * page. | |
359 | */ | |
360 | req.new_page = 1; | |
361 | else | |
362 | /* | |
363 | * Not a hole, the change will not add any new | |
364 | * indexing information, budget for page | |
365 | * change. | |
366 | */ | |
367 | req.dirtied_page = 1; | |
368 | ||
369 | if (appending) { | |
370 | mutex_lock(&ui->ui_mutex); | |
371 | if (!ui->dirty) | |
372 | /* | |
373 | * The inode is clean but we will have to mark | |
374 | * it as dirty because we are appending. This | |
375 | * needs a budget. | |
376 | */ | |
377 | req.dirtied_ino = 1; | |
378 | } | |
379 | } | |
380 | ||
381 | return ubifs_budget_space(c, &req); | |
382 | } | |
383 | ||
384 | /* | |
385 | * This function is called when a page of data is going to be written. Since | |
386 | * the page of data will not necessarily go to the flash straight away, UBIFS | |
387 | * has to reserve space on the media for it, which is done by means of | |
388 | * budgeting. | |
389 | * | |
390 | * This is the hot-path of the file-system and we are trying to optimize it as | |
391 | * much as possible. For this reasons it is split on 2 parts - slow and fast. | |
392 | * | |
393 | * There many budgeting cases: | |
394 | * o a new page is appended - we have to budget for a new page and for | |
395 | * changing the inode; however, if the inode is already dirty, there is | |
396 | * no need to budget for it; | |
397 | * o an existing clean page is changed - we have budget for it; if the page | |
398 | * does not exist on the media (a hole), we have to budget for a new | |
399 | * page; otherwise, we may budget for changing an existing page; the | |
400 | * difference between these cases is that changing an existing page does | |
401 | * not introduce anything new to the FS indexing information, so it does | |
402 | * not grow, and smaller budget is acquired in this case; | |
403 | * o an existing dirty page is changed - no need to budget at all, because | |
404 | * the page budget has been acquired by earlier, when the page has been | |
405 | * marked dirty. | |
406 | * | |
407 | * UBIFS budgeting sub-system may force write-back if it thinks there is no | |
408 | * space to reserve. This imposes some locking restrictions and makes it | |
409 | * impossible to take into account the above cases, and makes it impossible to | |
410 | * optimize budgeting. | |
411 | * | |
412 | * The solution for this is that the fast path of 'ubifs_write_begin()' assumes | |
413 | * there is a plenty of flash space and the budget will be acquired quickly, | |
414 | * without forcing write-back. The slow path does not make this assumption. | |
415 | */ | |
416 | static int ubifs_write_begin(struct file *file, struct address_space *mapping, | |
417 | loff_t pos, unsigned len, unsigned flags, | |
418 | struct page **pagep, void **fsdata) | |
419 | { | |
420 | struct inode *inode = mapping->host; | |
421 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
422 | struct ubifs_inode *ui = ubifs_inode(inode); | |
423 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
424 | int uninitialized_var(err), appending = !!(pos + len > inode->i_size); | |
425 | struct page *page; | |
426 | ||
427 | ||
428 | ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size); | |
429 | ||
430 | if (unlikely(c->ro_media)) | |
431 | return -EROFS; | |
432 | ||
433 | /* Try out the fast-path part first */ | |
434 | page = __grab_cache_page(mapping, index); | |
435 | if (unlikely(!page)) | |
436 | return -ENOMEM; | |
437 | ||
438 | if (!PageUptodate(page)) { | |
439 | /* The page is not loaded from the flash */ | |
440 | if (!(pos & PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) | |
441 | /* | |
442 | * We change whole page so no need to load it. But we | |
443 | * have to set the @PG_checked flag to make the further | |
444 | * code the page is new. This might be not true, but it | |
445 | * is better to budget more that to read the page from | |
446 | * the media. | |
447 | */ | |
448 | SetPageChecked(page); | |
449 | else { | |
450 | err = do_readpage(page); | |
451 | if (err) { | |
452 | unlock_page(page); | |
453 | page_cache_release(page); | |
454 | return err; | |
455 | } | |
456 | } | |
457 | ||
458 | SetPageUptodate(page); | |
459 | ClearPageError(page); | |
460 | } | |
461 | ||
462 | err = allocate_budget(c, page, ui, appending); | |
463 | if (unlikely(err)) { | |
464 | ubifs_assert(err == -ENOSPC); | |
465 | /* | |
466 | * Budgeting failed which means it would have to force | |
467 | * write-back but didn't, because we set the @fast flag in the | |
468 | * request. Write-back cannot be done now, while we have the | |
469 | * page locked, because it would deadlock. Unlock and free | |
470 | * everything and fall-back to slow-path. | |
471 | */ | |
472 | if (appending) { | |
473 | ubifs_assert(mutex_is_locked(&ui->ui_mutex)); | |
474 | mutex_unlock(&ui->ui_mutex); | |
475 | } | |
476 | unlock_page(page); | |
477 | page_cache_release(page); | |
478 | ||
479 | return write_begin_slow(mapping, pos, len, pagep); | |
480 | } | |
481 | ||
482 | /* | |
483 | * Whee, we aquired budgeting quickly - without involving | |
484 | * garbage-collection, committing or forceing write-back. We return | |
485 | * with @ui->ui_mutex locked if we are appending pages, and unlocked | |
486 | * otherwise. This is an optimization (slightly hacky though). | |
487 | */ | |
488 | *pagep = page; | |
489 | return 0; | |
490 | ||
491 | } | |
492 | ||
493 | /** | |
494 | * cancel_budget - cancel budget. | |
495 | * @c: UBIFS file-system description object | |
496 | * @page: page to cancel budget for | |
497 | * @ui: UBIFS inode object the page belongs to | |
498 | * @appending: non-zero if the page is appended | |
499 | * | |
500 | * This is a helper function for a page write operation. It unlocks the | |
501 | * @ui->ui_mutex in case of appending. | |
502 | */ | |
503 | static void cancel_budget(struct ubifs_info *c, struct page *page, | |
504 | struct ubifs_inode *ui, int appending) | |
505 | { | |
506 | if (appending) { | |
507 | if (!ui->dirty) | |
508 | ubifs_release_dirty_inode_budget(c, ui); | |
509 | mutex_unlock(&ui->ui_mutex); | |
510 | } | |
511 | if (!PagePrivate(page)) { | |
512 | if (PageChecked(page)) | |
513 | release_new_page_budget(c); | |
514 | else | |
515 | release_existing_page_budget(c); | |
516 | } | |
517 | } | |
518 | ||
519 | static int ubifs_write_end(struct file *file, struct address_space *mapping, | |
520 | loff_t pos, unsigned len, unsigned copied, | |
521 | struct page *page, void *fsdata) | |
522 | { | |
523 | struct inode *inode = mapping->host; | |
524 | struct ubifs_inode *ui = ubifs_inode(inode); | |
525 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
526 | loff_t end_pos = pos + len; | |
527 | int appending = !!(end_pos > inode->i_size); | |
528 | ||
529 | dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld", | |
530 | inode->i_ino, pos, page->index, len, copied, inode->i_size); | |
531 | ||
532 | if (unlikely(copied < len && len == PAGE_CACHE_SIZE)) { | |
533 | /* | |
534 | * VFS copied less data to the page that it intended and | |
535 | * declared in its '->write_begin()' call via the @len | |
536 | * argument. If the page was not up-to-date, and @len was | |
537 | * @PAGE_CACHE_SIZE, the 'ubifs_write_begin()' function did | |
538 | * not load it from the media (for optimization reasons). This | |
539 | * means that part of the page contains garbage. So read the | |
540 | * page now. | |
541 | */ | |
542 | dbg_gen("copied %d instead of %d, read page and repeat", | |
543 | copied, len); | |
544 | cancel_budget(c, page, ui, appending); | |
545 | ||
546 | /* | |
547 | * Return 0 to force VFS to repeat the whole operation, or the | |
548 | * error code if 'do_readpage()' failes. | |
549 | */ | |
550 | copied = do_readpage(page); | |
551 | goto out; | |
552 | } | |
553 | ||
554 | if (!PagePrivate(page)) { | |
555 | SetPagePrivate(page); | |
556 | atomic_long_inc(&c->dirty_pg_cnt); | |
557 | __set_page_dirty_nobuffers(page); | |
558 | } | |
559 | ||
560 | if (appending) { | |
561 | i_size_write(inode, end_pos); | |
562 | ui->ui_size = end_pos; | |
563 | /* | |
564 | * Note, we do not set @I_DIRTY_PAGES (which means that the | |
565 | * inode has dirty pages), this has been done in | |
566 | * '__set_page_dirty_nobuffers()'. | |
567 | */ | |
568 | __mark_inode_dirty(inode, I_DIRTY_DATASYNC); | |
569 | ubifs_assert(mutex_is_locked(&ui->ui_mutex)); | |
570 | mutex_unlock(&ui->ui_mutex); | |
571 | } | |
572 | ||
573 | out: | |
574 | unlock_page(page); | |
575 | page_cache_release(page); | |
576 | return copied; | |
577 | } | |
578 | ||
579 | static int ubifs_readpage(struct file *file, struct page *page) | |
580 | { | |
581 | do_readpage(page); | |
582 | unlock_page(page); | |
583 | return 0; | |
584 | } | |
585 | ||
586 | static int do_writepage(struct page *page, int len) | |
587 | { | |
588 | int err = 0, i, blen; | |
589 | unsigned int block; | |
590 | void *addr; | |
591 | union ubifs_key key; | |
592 | struct inode *inode = page->mapping->host; | |
593 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
594 | ||
595 | #ifdef UBIFS_DEBUG | |
596 | spin_lock(&ui->ui_lock); | |
597 | ubifs_assert(page->index <= ui->synced_i_size << PAGE_CACHE_SIZE); | |
598 | spin_unlock(&ui->ui_lock); | |
599 | #endif | |
600 | ||
601 | /* Update radix tree tags */ | |
602 | set_page_writeback(page); | |
603 | ||
604 | addr = kmap(page); | |
605 | block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; | |
606 | i = 0; | |
607 | while (len) { | |
608 | blen = min_t(int, len, UBIFS_BLOCK_SIZE); | |
609 | data_key_init(c, &key, inode->i_ino, block); | |
610 | err = ubifs_jnl_write_data(c, inode, &key, addr, blen); | |
611 | if (err) | |
612 | break; | |
613 | if (++i >= UBIFS_BLOCKS_PER_PAGE) | |
614 | break; | |
615 | block += 1; | |
616 | addr += blen; | |
617 | len -= blen; | |
618 | } | |
619 | if (err) { | |
620 | SetPageError(page); | |
621 | ubifs_err("cannot write page %lu of inode %lu, error %d", | |
622 | page->index, inode->i_ino, err); | |
623 | ubifs_ro_mode(c, err); | |
624 | } | |
625 | ||
626 | ubifs_assert(PagePrivate(page)); | |
627 | if (PageChecked(page)) | |
628 | release_new_page_budget(c); | |
629 | else | |
630 | release_existing_page_budget(c); | |
631 | ||
632 | atomic_long_dec(&c->dirty_pg_cnt); | |
633 | ClearPagePrivate(page); | |
634 | ClearPageChecked(page); | |
635 | ||
636 | kunmap(page); | |
637 | unlock_page(page); | |
638 | end_page_writeback(page); | |
639 | return err; | |
640 | } | |
641 | ||
642 | /* | |
643 | * When writing-back dirty inodes, VFS first writes-back pages belonging to the | |
644 | * inode, then the inode itself. For UBIFS this may cause a problem. Consider a | |
645 | * situation when a we have an inode with size 0, then a megabyte of data is | |
646 | * appended to the inode, then write-back starts and flushes some amount of the | |
647 | * dirty pages, the journal becomes full, commit happens and finishes, and then | |
648 | * an unclean reboot happens. When the file system is mounted next time, the | |
649 | * inode size would still be 0, but there would be many pages which are beyond | |
650 | * the inode size, they would be indexed and consume flash space. Because the | |
651 | * journal has been committed, the replay would not be able to detect this | |
652 | * situation and correct the inode size. This means UBIFS would have to scan | |
653 | * whole index and correct all inode sizes, which is long an unacceptable. | |
654 | * | |
655 | * To prevent situations like this, UBIFS writes pages back only if they are | |
656 | * within last synchronized inode size, i.e. the the size which has been | |
657 | * written to the flash media last time. Otherwise, UBIFS forces inode | |
658 | * write-back, thus making sure the on-flash inode contains current inode size, | |
659 | * and then keeps writing pages back. | |
660 | * | |
661 | * Some locking issues explanation. 'ubifs_writepage()' first is called with | |
662 | * the page locked, and it locks @ui_mutex. However, write-back does take inode | |
663 | * @i_mutex, which means other VFS operations may be run on this inode at the | |
664 | * same time. And the problematic one is truncation to smaller size, from where | |
665 | * we have to call 'vmtruncate()', which first changes @inode->i_size, then | |
666 | * drops the truncated pages. And while dropping the pages, it takes the page | |
667 | * lock. This means that 'do_truncation()' cannot call 'vmtruncate()' with | |
668 | * @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'. This | |
669 | * means that @inode->i_size is changed while @ui_mutex is unlocked. | |
670 | * | |
671 | * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond | |
672 | * inode size. How do we do this if @inode->i_size may became smaller while we | |
673 | * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the | |
674 | * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size | |
675 | * internally and updates it under @ui_mutex. | |
676 | * | |
677 | * Q: why we do not worry that if we race with truncation, we may end up with a | |
678 | * situation when the inode is truncated while we are in the middle of | |
679 | * 'do_writepage()', so we do write beyond inode size? | |
680 | * A: If we are in the middle of 'do_writepage()', truncation would be locked | |
681 | * on the page lock and it would not write the truncated inode node to the | |
682 | * journal before we have finished. | |
683 | */ | |
684 | static int ubifs_writepage(struct page *page, struct writeback_control *wbc) | |
685 | { | |
686 | struct inode *inode = page->mapping->host; | |
687 | struct ubifs_inode *ui = ubifs_inode(inode); | |
688 | loff_t i_size = i_size_read(inode), synced_i_size; | |
689 | pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
690 | int err, len = i_size & (PAGE_CACHE_SIZE - 1); | |
691 | void *kaddr; | |
692 | ||
693 | dbg_gen("ino %lu, pg %lu, pg flags %#lx", | |
694 | inode->i_ino, page->index, page->flags); | |
695 | ubifs_assert(PagePrivate(page)); | |
696 | ||
697 | /* Is the page fully outside @i_size? (truncate in progress) */ | |
698 | if (page->index > end_index || (page->index == end_index && !len)) { | |
699 | err = 0; | |
700 | goto out_unlock; | |
701 | } | |
702 | ||
703 | spin_lock(&ui->ui_lock); | |
704 | synced_i_size = ui->synced_i_size; | |
705 | spin_unlock(&ui->ui_lock); | |
706 | ||
707 | /* Is the page fully inside @i_size? */ | |
708 | if (page->index < end_index) { | |
709 | if (page->index >= synced_i_size >> PAGE_CACHE_SHIFT) { | |
710 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
711 | if (err) | |
712 | goto out_unlock; | |
713 | /* | |
714 | * The inode has been written, but the write-buffer has | |
715 | * not been synchronized, so in case of an unclean | |
716 | * reboot we may end up with some pages beyond inode | |
717 | * size, but they would be in the journal (because | |
718 | * commit flushes write buffers) and recovery would deal | |
719 | * with this. | |
720 | */ | |
721 | } | |
722 | return do_writepage(page, PAGE_CACHE_SIZE); | |
723 | } | |
724 | ||
725 | /* | |
726 | * The page straddles @i_size. It must be zeroed out on each and every | |
727 | * writepage invocation because it may be mmapped. "A file is mapped | |
728 | * in multiples of the page size. For a file that is not a multiple of | |
729 | * the page size, the remaining memory is zeroed when mapped, and | |
730 | * writes to that region are not written out to the file." | |
731 | */ | |
732 | kaddr = kmap_atomic(page, KM_USER0); | |
733 | memset(kaddr + len, 0, PAGE_CACHE_SIZE - len); | |
734 | flush_dcache_page(page); | |
735 | kunmap_atomic(kaddr, KM_USER0); | |
736 | ||
737 | if (i_size > synced_i_size) { | |
738 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
739 | if (err) | |
740 | goto out_unlock; | |
741 | } | |
742 | ||
743 | return do_writepage(page, len); | |
744 | ||
745 | out_unlock: | |
746 | unlock_page(page); | |
747 | return err; | |
748 | } | |
749 | ||
750 | /** | |
751 | * do_attr_changes - change inode attributes. | |
752 | * @inode: inode to change attributes for | |
753 | * @attr: describes attributes to change | |
754 | */ | |
755 | static void do_attr_changes(struct inode *inode, const struct iattr *attr) | |
756 | { | |
757 | if (attr->ia_valid & ATTR_UID) | |
758 | inode->i_uid = attr->ia_uid; | |
759 | if (attr->ia_valid & ATTR_GID) | |
760 | inode->i_gid = attr->ia_gid; | |
761 | if (attr->ia_valid & ATTR_ATIME) | |
762 | inode->i_atime = timespec_trunc(attr->ia_atime, | |
763 | inode->i_sb->s_time_gran); | |
764 | if (attr->ia_valid & ATTR_MTIME) | |
765 | inode->i_mtime = timespec_trunc(attr->ia_mtime, | |
766 | inode->i_sb->s_time_gran); | |
767 | if (attr->ia_valid & ATTR_CTIME) | |
768 | inode->i_ctime = timespec_trunc(attr->ia_ctime, | |
769 | inode->i_sb->s_time_gran); | |
770 | if (attr->ia_valid & ATTR_MODE) { | |
771 | umode_t mode = attr->ia_mode; | |
772 | ||
773 | if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) | |
774 | mode &= ~S_ISGID; | |
775 | inode->i_mode = mode; | |
776 | } | |
777 | } | |
778 | ||
779 | /** | |
780 | * do_truncation - truncate an inode. | |
781 | * @c: UBIFS file-system description object | |
782 | * @inode: inode to truncate | |
783 | * @attr: inode attribute changes description | |
784 | * | |
785 | * This function implements VFS '->setattr()' call when the inode is truncated | |
786 | * to a smaller size. Returns zero in case of success and a negative error code | |
787 | * in case of failure. | |
788 | */ | |
789 | static int do_truncation(struct ubifs_info *c, struct inode *inode, | |
790 | const struct iattr *attr) | |
791 | { | |
792 | int err; | |
793 | struct ubifs_budget_req req; | |
794 | loff_t old_size = inode->i_size, new_size = attr->ia_size; | |
795 | int offset = new_size & (UBIFS_BLOCK_SIZE - 1); | |
796 | struct ubifs_inode *ui = ubifs_inode(inode); | |
797 | ||
798 | dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size); | |
799 | memset(&req, 0, sizeof(struct ubifs_budget_req)); | |
800 | ||
801 | /* | |
802 | * If this is truncation to a smaller size, and we do not truncate on a | |
803 | * block boundary, budget for changing one data block, because the last | |
804 | * block will be re-written. | |
805 | */ | |
806 | if (new_size & (UBIFS_BLOCK_SIZE - 1)) | |
807 | req.dirtied_page = 1; | |
808 | ||
809 | req.dirtied_ino = 1; | |
810 | /* A funny way to budget for truncation node */ | |
811 | req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ; | |
812 | err = ubifs_budget_space(c, &req); | |
813 | if (err) | |
814 | return err; | |
815 | ||
816 | err = vmtruncate(inode, new_size); | |
817 | if (err) | |
818 | goto out_budg; | |
819 | ||
820 | if (offset) { | |
821 | pgoff_t index = new_size >> PAGE_CACHE_SHIFT; | |
822 | struct page *page; | |
823 | ||
824 | page = find_lock_page(inode->i_mapping, index); | |
825 | if (page) { | |
826 | if (PageDirty(page)) { | |
827 | /* | |
828 | * 'ubifs_jnl_truncate()' will try to truncate | |
829 | * the last data node, but it contains | |
830 | * out-of-date data because the page is dirty. | |
831 | * Write the page now, so that | |
832 | * 'ubifs_jnl_truncate()' will see an already | |
833 | * truncated (and up to date) data node. | |
834 | */ | |
835 | ubifs_assert(PagePrivate(page)); | |
836 | ||
837 | clear_page_dirty_for_io(page); | |
838 | if (UBIFS_BLOCKS_PER_PAGE_SHIFT) | |
839 | offset = new_size & | |
840 | (PAGE_CACHE_SIZE - 1); | |
841 | err = do_writepage(page, offset); | |
842 | page_cache_release(page); | |
843 | if (err) | |
844 | goto out_budg; | |
845 | /* | |
846 | * We could now tell 'ubifs_jnl_truncate()' not | |
847 | * to read the last block. | |
848 | */ | |
849 | } else { | |
850 | /* | |
851 | * We could 'kmap()' the page and pass the data | |
852 | * to 'ubifs_jnl_truncate()' to save it from | |
853 | * having to read it. | |
854 | */ | |
855 | unlock_page(page); | |
856 | page_cache_release(page); | |
857 | } | |
858 | } | |
859 | } | |
860 | ||
861 | mutex_lock(&ui->ui_mutex); | |
862 | ui->ui_size = inode->i_size; | |
863 | /* Truncation changes inode [mc]time */ | |
864 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
865 | /* The other attributes may be changed at the same time as well */ | |
866 | do_attr_changes(inode, attr); | |
867 | ||
868 | err = ubifs_jnl_truncate(c, inode, old_size, new_size); | |
869 | mutex_unlock(&ui->ui_mutex); | |
870 | out_budg: | |
871 | ubifs_release_budget(c, &req); | |
872 | return err; | |
873 | } | |
874 | ||
875 | /** | |
876 | * do_setattr - change inode attributes. | |
877 | * @c: UBIFS file-system description object | |
878 | * @inode: inode to change attributes for | |
879 | * @attr: inode attribute changes description | |
880 | * | |
881 | * This function implements VFS '->setattr()' call for all cases except | |
882 | * truncations to smaller size. Returns zero in case of success and a negative | |
883 | * error code in case of failure. | |
884 | */ | |
885 | static int do_setattr(struct ubifs_info *c, struct inode *inode, | |
886 | const struct iattr *attr) | |
887 | { | |
888 | int err, release; | |
889 | loff_t new_size = attr->ia_size; | |
890 | struct ubifs_inode *ui = ubifs_inode(inode); | |
891 | struct ubifs_budget_req req = { .dirtied_ino = 1, | |
892 | .dirtied_ino_d = ui->data_len }; | |
893 | ||
894 | err = ubifs_budget_space(c, &req); | |
895 | if (err) | |
896 | return err; | |
897 | ||
898 | if (attr->ia_valid & ATTR_SIZE) { | |
899 | dbg_gen("size %lld -> %lld", inode->i_size, new_size); | |
900 | err = vmtruncate(inode, new_size); | |
901 | if (err) | |
902 | goto out; | |
903 | } | |
904 | ||
905 | mutex_lock(&ui->ui_mutex); | |
906 | if (attr->ia_valid & ATTR_SIZE) { | |
907 | /* Truncation changes inode [mc]time */ | |
908 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
909 | /* 'vmtruncate()' changed @i_size, update @ui_size */ | |
910 | ui->ui_size = inode->i_size; | |
911 | } | |
912 | ||
913 | do_attr_changes(inode, attr); | |
914 | ||
915 | release = ui->dirty; | |
916 | if (attr->ia_valid & ATTR_SIZE) | |
917 | /* | |
918 | * Inode length changed, so we have to make sure | |
919 | * @I_DIRTY_DATASYNC is set. | |
920 | */ | |
921 | __mark_inode_dirty(inode, I_DIRTY_SYNC | I_DIRTY_DATASYNC); | |
922 | else | |
923 | mark_inode_dirty_sync(inode); | |
924 | mutex_unlock(&ui->ui_mutex); | |
925 | ||
926 | if (release) | |
927 | ubifs_release_budget(c, &req); | |
928 | if (IS_SYNC(inode)) | |
929 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
930 | return err; | |
931 | ||
932 | out: | |
933 | ubifs_release_budget(c, &req); | |
934 | return err; | |
935 | } | |
936 | ||
937 | int ubifs_setattr(struct dentry *dentry, struct iattr *attr) | |
938 | { | |
939 | int err; | |
940 | struct inode *inode = dentry->d_inode; | |
941 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
942 | ||
943 | dbg_gen("ino %lu, ia_valid %#x", inode->i_ino, attr->ia_valid); | |
944 | err = inode_change_ok(inode, attr); | |
945 | if (err) | |
946 | return err; | |
947 | ||
948 | err = dbg_check_synced_i_size(inode); | |
949 | if (err) | |
950 | return err; | |
951 | ||
952 | if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size) | |
953 | /* Truncation to a smaller size */ | |
954 | err = do_truncation(c, inode, attr); | |
955 | else | |
956 | err = do_setattr(c, inode, attr); | |
957 | ||
958 | return err; | |
959 | } | |
960 | ||
961 | static void ubifs_invalidatepage(struct page *page, unsigned long offset) | |
962 | { | |
963 | struct inode *inode = page->mapping->host; | |
964 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
965 | ||
966 | ubifs_assert(PagePrivate(page)); | |
967 | if (offset) | |
968 | /* Partial page remains dirty */ | |
969 | return; | |
970 | ||
971 | if (PageChecked(page)) | |
972 | release_new_page_budget(c); | |
973 | else | |
974 | release_existing_page_budget(c); | |
975 | ||
976 | atomic_long_dec(&c->dirty_pg_cnt); | |
977 | ClearPagePrivate(page); | |
978 | ClearPageChecked(page); | |
979 | } | |
980 | ||
981 | static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd) | |
982 | { | |
983 | struct ubifs_inode *ui = ubifs_inode(dentry->d_inode); | |
984 | ||
985 | nd_set_link(nd, ui->data); | |
986 | return NULL; | |
987 | } | |
988 | ||
989 | int ubifs_fsync(struct file *file, struct dentry *dentry, int datasync) | |
990 | { | |
991 | struct inode *inode = dentry->d_inode; | |
992 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
993 | int err; | |
994 | ||
995 | dbg_gen("syncing inode %lu", inode->i_ino); | |
996 | ||
997 | /* | |
998 | * VFS has already synchronized dirty pages for this inode. Synchronize | |
999 | * the inode unless this is a 'datasync()' call. | |
1000 | */ | |
1001 | if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) { | |
1002 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
1003 | if (err) | |
1004 | return err; | |
1005 | } | |
1006 | ||
1007 | /* | |
1008 | * Nodes related to this inode may still sit in a write-buffer. Flush | |
1009 | * them. | |
1010 | */ | |
1011 | err = ubifs_sync_wbufs_by_inode(c, inode); | |
1012 | if (err) | |
1013 | return err; | |
1014 | ||
1015 | return 0; | |
1016 | } | |
1017 | ||
1018 | /** | |
1019 | * mctime_update_needed - check if mtime or ctime update is needed. | |
1020 | * @inode: the inode to do the check for | |
1021 | * @now: current time | |
1022 | * | |
1023 | * This helper function checks if the inode mtime/ctime should be updated or | |
1024 | * not. If current values of the time-stamps are within the UBIFS inode time | |
1025 | * granularity, they are not updated. This is an optimization. | |
1026 | */ | |
1027 | static inline int mctime_update_needed(const struct inode *inode, | |
1028 | const struct timespec *now) | |
1029 | { | |
1030 | if (!timespec_equal(&inode->i_mtime, now) || | |
1031 | !timespec_equal(&inode->i_ctime, now)) | |
1032 | return 1; | |
1033 | return 0; | |
1034 | } | |
1035 | ||
1036 | /** | |
1037 | * update_ctime - update mtime and ctime of an inode. | |
1038 | * @c: UBIFS file-system description object | |
1039 | * @inode: inode to update | |
1040 | * | |
1041 | * This function updates mtime and ctime of the inode if it is not equivalent to | |
1042 | * current time. Returns zero in case of success and a negative error code in | |
1043 | * case of failure. | |
1044 | */ | |
1045 | static int update_mctime(struct ubifs_info *c, struct inode *inode) | |
1046 | { | |
1047 | struct timespec now = ubifs_current_time(inode); | |
1048 | struct ubifs_inode *ui = ubifs_inode(inode); | |
1049 | ||
1050 | if (mctime_update_needed(inode, &now)) { | |
1051 | int err, release; | |
1052 | struct ubifs_budget_req req = { .dirtied_ino = 1, | |
1053 | .dirtied_ino_d = ui->data_len }; | |
1054 | ||
1055 | err = ubifs_budget_space(c, &req); | |
1056 | if (err) | |
1057 | return err; | |
1058 | ||
1059 | mutex_lock(&ui->ui_mutex); | |
1060 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
1061 | release = ui->dirty; | |
1062 | mark_inode_dirty_sync(inode); | |
1063 | mutex_unlock(&ui->ui_mutex); | |
1064 | if (release) | |
1065 | ubifs_release_budget(c, &req); | |
1066 | } | |
1067 | ||
1068 | return 0; | |
1069 | } | |
1070 | ||
1071 | static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov, | |
1072 | unsigned long nr_segs, loff_t pos) | |
1073 | { | |
1074 | int err; | |
1075 | ssize_t ret; | |
1076 | struct inode *inode = iocb->ki_filp->f_mapping->host; | |
1077 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
1078 | ||
1079 | err = update_mctime(c, inode); | |
1080 | if (err) | |
1081 | return err; | |
1082 | ||
1083 | ret = generic_file_aio_write(iocb, iov, nr_segs, pos); | |
1084 | if (ret < 0) | |
1085 | return ret; | |
1086 | ||
1087 | if (ret > 0 && (IS_SYNC(inode) || iocb->ki_filp->f_flags & O_SYNC)) { | |
1088 | err = ubifs_sync_wbufs_by_inode(c, inode); | |
1089 | if (err) | |
1090 | return err; | |
1091 | } | |
1092 | ||
1093 | return ret; | |
1094 | } | |
1095 | ||
1096 | static int ubifs_set_page_dirty(struct page *page) | |
1097 | { | |
1098 | int ret; | |
1099 | ||
1100 | ret = __set_page_dirty_nobuffers(page); | |
1101 | /* | |
1102 | * An attempt to dirty a page without budgeting for it - should not | |
1103 | * happen. | |
1104 | */ | |
1105 | ubifs_assert(ret == 0); | |
1106 | return ret; | |
1107 | } | |
1108 | ||
1109 | static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags) | |
1110 | { | |
1111 | /* | |
1112 | * An attempt to release a dirty page without budgeting for it - should | |
1113 | * not happen. | |
1114 | */ | |
1115 | if (PageWriteback(page)) | |
1116 | return 0; | |
1117 | ubifs_assert(PagePrivate(page)); | |
1118 | ubifs_assert(0); | |
1119 | ClearPagePrivate(page); | |
1120 | ClearPageChecked(page); | |
1121 | return 1; | |
1122 | } | |
1123 | ||
1124 | /* | |
1125 | * mmap()d file has taken write protection fault and is being made | |
1126 | * writable. UBIFS must ensure page is budgeted for. | |
1127 | */ | |
1128 | static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page) | |
1129 | { | |
1130 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; | |
1131 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
1132 | struct timespec now = ubifs_current_time(inode); | |
1133 | struct ubifs_budget_req req = { .new_page = 1 }; | |
1134 | int err, update_time; | |
1135 | ||
1136 | dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index, | |
1137 | i_size_read(inode)); | |
1138 | ubifs_assert(!(inode->i_sb->s_flags & MS_RDONLY)); | |
1139 | ||
1140 | if (unlikely(c->ro_media)) | |
1141 | return -EROFS; | |
1142 | ||
1143 | /* | |
1144 | * We have not locked @page so far so we may budget for changing the | |
1145 | * page. Note, we cannot do this after we locked the page, because | |
1146 | * budgeting may cause write-back which would cause deadlock. | |
1147 | * | |
1148 | * At the moment we do not know whether the page is dirty or not, so we | |
1149 | * assume that it is not and budget for a new page. We could look at | |
1150 | * the @PG_private flag and figure this out, but we may race with write | |
1151 | * back and the page state may change by the time we lock it, so this | |
1152 | * would need additional care. We do not bother with this at the | |
1153 | * moment, although it might be good idea to do. Instead, we allocate | |
1154 | * budget for a new page and amend it later on if the page was in fact | |
1155 | * dirty. | |
1156 | * | |
1157 | * The budgeting-related logic of this function is similar to what we | |
1158 | * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there | |
1159 | * for more comments. | |
1160 | */ | |
1161 | update_time = mctime_update_needed(inode, &now); | |
1162 | if (update_time) | |
1163 | /* | |
1164 | * We have to change inode time stamp which requires extra | |
1165 | * budgeting. | |
1166 | */ | |
1167 | req.dirtied_ino = 1; | |
1168 | ||
1169 | err = ubifs_budget_space(c, &req); | |
1170 | if (unlikely(err)) { | |
1171 | if (err == -ENOSPC) | |
1172 | ubifs_warn("out of space for mmapped file " | |
1173 | "(inode number %lu)", inode->i_ino); | |
1174 | return err; | |
1175 | } | |
1176 | ||
1177 | lock_page(page); | |
1178 | if (unlikely(page->mapping != inode->i_mapping || | |
1179 | page_offset(page) > i_size_read(inode))) { | |
1180 | /* Page got truncated out from underneath us */ | |
1181 | err = -EINVAL; | |
1182 | goto out_unlock; | |
1183 | } | |
1184 | ||
1185 | if (PagePrivate(page)) | |
1186 | release_new_page_budget(c); | |
1187 | else { | |
1188 | if (!PageChecked(page)) | |
1189 | ubifs_convert_page_budget(c); | |
1190 | SetPagePrivate(page); | |
1191 | atomic_long_inc(&c->dirty_pg_cnt); | |
1192 | __set_page_dirty_nobuffers(page); | |
1193 | } | |
1194 | ||
1195 | if (update_time) { | |
1196 | int release; | |
1197 | struct ubifs_inode *ui = ubifs_inode(inode); | |
1198 | ||
1199 | mutex_lock(&ui->ui_mutex); | |
1200 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
1201 | release = ui->dirty; | |
1202 | mark_inode_dirty_sync(inode); | |
1203 | mutex_unlock(&ui->ui_mutex); | |
1204 | if (release) | |
1205 | ubifs_release_dirty_inode_budget(c, ui); | |
1206 | } | |
1207 | ||
1208 | unlock_page(page); | |
1209 | return 0; | |
1210 | ||
1211 | out_unlock: | |
1212 | unlock_page(page); | |
1213 | ubifs_release_budget(c, &req); | |
1214 | return err; | |
1215 | } | |
1216 | ||
1217 | static struct vm_operations_struct ubifs_file_vm_ops = { | |
1218 | .fault = filemap_fault, | |
1219 | .page_mkwrite = ubifs_vm_page_mkwrite, | |
1220 | }; | |
1221 | ||
1222 | static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma) | |
1223 | { | |
1224 | int err; | |
1225 | ||
1226 | /* 'generic_file_mmap()' takes care of NOMMU case */ | |
1227 | err = generic_file_mmap(file, vma); | |
1228 | if (err) | |
1229 | return err; | |
1230 | vma->vm_ops = &ubifs_file_vm_ops; | |
1231 | return 0; | |
1232 | } | |
1233 | ||
1234 | struct address_space_operations ubifs_file_address_operations = { | |
1235 | .readpage = ubifs_readpage, | |
1236 | .writepage = ubifs_writepage, | |
1237 | .write_begin = ubifs_write_begin, | |
1238 | .write_end = ubifs_write_end, | |
1239 | .invalidatepage = ubifs_invalidatepage, | |
1240 | .set_page_dirty = ubifs_set_page_dirty, | |
1241 | .releasepage = ubifs_releasepage, | |
1242 | }; | |
1243 | ||
1244 | struct inode_operations ubifs_file_inode_operations = { | |
1245 | .setattr = ubifs_setattr, | |
1246 | .getattr = ubifs_getattr, | |
1247 | #ifdef CONFIG_UBIFS_FS_XATTR | |
1248 | .setxattr = ubifs_setxattr, | |
1249 | .getxattr = ubifs_getxattr, | |
1250 | .listxattr = ubifs_listxattr, | |
1251 | .removexattr = ubifs_removexattr, | |
1252 | #endif | |
1253 | }; | |
1254 | ||
1255 | struct inode_operations ubifs_symlink_inode_operations = { | |
1256 | .readlink = generic_readlink, | |
1257 | .follow_link = ubifs_follow_link, | |
1258 | .setattr = ubifs_setattr, | |
1259 | .getattr = ubifs_getattr, | |
1260 | }; | |
1261 | ||
1262 | struct file_operations ubifs_file_operations = { | |
1263 | .llseek = generic_file_llseek, | |
1264 | .read = do_sync_read, | |
1265 | .write = do_sync_write, | |
1266 | .aio_read = generic_file_aio_read, | |
1267 | .aio_write = ubifs_aio_write, | |
1268 | .mmap = ubifs_file_mmap, | |
1269 | .fsync = ubifs_fsync, | |
1270 | .unlocked_ioctl = ubifs_ioctl, | |
1271 | .splice_read = generic_file_splice_read, | |
1272 | #ifdef CONFIG_COMPAT | |
1273 | .compat_ioctl = ubifs_compat_ioctl, | |
1274 | #endif | |
1275 | }; |