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1e51764a AB |
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> | |
3f8206d4 | 56 | #include <linux/namei.h> |
1e51764a AB |
57 | |
58 | static int read_block(struct inode *inode, void *addr, unsigned int block, | |
59 | struct ubifs_data_node *dn) | |
60 | { | |
61 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
62 | int err, len, out_len; | |
63 | union ubifs_key key; | |
64 | unsigned int dlen; | |
65 | ||
66 | data_key_init(c, &key, inode->i_ino, block); | |
67 | err = ubifs_tnc_lookup(c, &key, dn); | |
68 | if (err) { | |
69 | if (err == -ENOENT) | |
70 | /* Not found, so it must be a hole */ | |
71 | memset(addr, 0, UBIFS_BLOCK_SIZE); | |
72 | return err; | |
73 | } | |
74 | ||
75 | ubifs_assert(dn->ch.sqnum > ubifs_inode(inode)->creat_sqnum); | |
76 | ||
77 | len = le32_to_cpu(dn->size); | |
78 | if (len <= 0 || len > UBIFS_BLOCK_SIZE) | |
79 | goto dump; | |
80 | ||
81 | dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ; | |
82 | out_len = UBIFS_BLOCK_SIZE; | |
83 | err = ubifs_decompress(&dn->data, dlen, addr, &out_len, | |
84 | le16_to_cpu(dn->compr_type)); | |
85 | if (err || len != out_len) | |
86 | goto dump; | |
87 | ||
88 | /* | |
89 | * Data length can be less than a full block, even for blocks that are | |
90 | * not the last in the file (e.g., as a result of making a hole and | |
91 | * appending data). Ensure that the remainder is zeroed out. | |
92 | */ | |
93 | if (len < UBIFS_BLOCK_SIZE) | |
94 | memset(addr + len, 0, UBIFS_BLOCK_SIZE - len); | |
95 | ||
96 | return 0; | |
97 | ||
98 | dump: | |
99 | ubifs_err("bad data node (block %u, inode %lu)", | |
100 | block, inode->i_ino); | |
101 | dbg_dump_node(c, dn); | |
102 | return -EINVAL; | |
103 | } | |
104 | ||
105 | static int do_readpage(struct page *page) | |
106 | { | |
107 | void *addr; | |
108 | int err = 0, i; | |
109 | unsigned int block, beyond; | |
110 | struct ubifs_data_node *dn; | |
111 | struct inode *inode = page->mapping->host; | |
112 | loff_t i_size = i_size_read(inode); | |
113 | ||
114 | dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx", | |
115 | inode->i_ino, page->index, i_size, page->flags); | |
116 | ubifs_assert(!PageChecked(page)); | |
117 | ubifs_assert(!PagePrivate(page)); | |
118 | ||
119 | addr = kmap(page); | |
120 | ||
121 | block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; | |
122 | beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT; | |
123 | if (block >= beyond) { | |
124 | /* Reading beyond inode */ | |
125 | SetPageChecked(page); | |
126 | memset(addr, 0, PAGE_CACHE_SIZE); | |
127 | goto out; | |
128 | } | |
129 | ||
130 | dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS); | |
131 | if (!dn) { | |
132 | err = -ENOMEM; | |
133 | goto error; | |
134 | } | |
135 | ||
136 | i = 0; | |
137 | while (1) { | |
138 | int ret; | |
139 | ||
140 | if (block >= beyond) { | |
141 | /* Reading beyond inode */ | |
142 | err = -ENOENT; | |
143 | memset(addr, 0, UBIFS_BLOCK_SIZE); | |
144 | } else { | |
145 | ret = read_block(inode, addr, block, dn); | |
146 | if (ret) { | |
147 | err = ret; | |
148 | if (err != -ENOENT) | |
149 | break; | |
150 | } | |
151 | } | |
152 | if (++i >= UBIFS_BLOCKS_PER_PAGE) | |
153 | break; | |
154 | block += 1; | |
155 | addr += UBIFS_BLOCK_SIZE; | |
156 | } | |
157 | if (err) { | |
158 | if (err == -ENOENT) { | |
159 | /* Not found, so it must be a hole */ | |
160 | SetPageChecked(page); | |
161 | dbg_gen("hole"); | |
162 | goto out_free; | |
163 | } | |
164 | ubifs_err("cannot read page %lu of inode %lu, error %d", | |
165 | page->index, inode->i_ino, err); | |
166 | goto error; | |
167 | } | |
168 | ||
169 | out_free: | |
170 | kfree(dn); | |
171 | out: | |
172 | SetPageUptodate(page); | |
173 | ClearPageError(page); | |
174 | flush_dcache_page(page); | |
175 | kunmap(page); | |
176 | return 0; | |
177 | ||
178 | error: | |
179 | kfree(dn); | |
180 | ClearPageUptodate(page); | |
181 | SetPageError(page); | |
182 | flush_dcache_page(page); | |
183 | kunmap(page); | |
184 | return err; | |
185 | } | |
186 | ||
187 | /** | |
188 | * release_new_page_budget - release budget of a new page. | |
189 | * @c: UBIFS file-system description object | |
190 | * | |
191 | * This is a helper function which releases budget corresponding to the budget | |
192 | * of one new page of data. | |
193 | */ | |
194 | static void release_new_page_budget(struct ubifs_info *c) | |
195 | { | |
196 | struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 }; | |
197 | ||
198 | ubifs_release_budget(c, &req); | |
199 | } | |
200 | ||
201 | /** | |
202 | * release_existing_page_budget - release budget of an existing page. | |
203 | * @c: UBIFS file-system description object | |
204 | * | |
205 | * This is a helper function which releases budget corresponding to the budget | |
206 | * of changing one one page of data which already exists on the flash media. | |
207 | */ | |
208 | static void release_existing_page_budget(struct ubifs_info *c) | |
209 | { | |
210 | struct ubifs_budget_req req = { .dd_growth = c->page_budget}; | |
211 | ||
212 | ubifs_release_budget(c, &req); | |
213 | } | |
214 | ||
215 | static int write_begin_slow(struct address_space *mapping, | |
216 | loff_t pos, unsigned len, struct page **pagep) | |
217 | { | |
218 | struct inode *inode = mapping->host; | |
219 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
220 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
221 | struct ubifs_budget_req req = { .new_page = 1 }; | |
222 | int uninitialized_var(err), appending = !!(pos + len > inode->i_size); | |
223 | struct page *page; | |
224 | ||
225 | dbg_gen("ino %lu, pos %llu, len %u, i_size %lld", | |
226 | inode->i_ino, pos, len, inode->i_size); | |
227 | ||
228 | /* | |
229 | * At the slow path we have to budget before locking the page, because | |
230 | * budgeting may force write-back, which would wait on locked pages and | |
231 | * deadlock if we had the page locked. At this point we do not know | |
232 | * anything about the page, so assume that this is a new page which is | |
233 | * written to a hole. This corresponds to largest budget. Later the | |
234 | * budget will be amended if this is not true. | |
235 | */ | |
236 | if (appending) | |
237 | /* We are appending data, budget for inode change */ | |
238 | req.dirtied_ino = 1; | |
239 | ||
240 | err = ubifs_budget_space(c, &req); | |
241 | if (unlikely(err)) | |
242 | return err; | |
243 | ||
244 | page = __grab_cache_page(mapping, index); | |
245 | if (unlikely(!page)) { | |
246 | ubifs_release_budget(c, &req); | |
247 | return -ENOMEM; | |
248 | } | |
249 | ||
250 | if (!PageUptodate(page)) { | |
251 | if (!(pos & PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) | |
252 | SetPageChecked(page); | |
253 | else { | |
254 | err = do_readpage(page); | |
255 | if (err) { | |
256 | unlock_page(page); | |
257 | page_cache_release(page); | |
258 | return err; | |
259 | } | |
260 | } | |
261 | ||
262 | SetPageUptodate(page); | |
263 | ClearPageError(page); | |
264 | } | |
265 | ||
266 | if (PagePrivate(page)) | |
267 | /* | |
268 | * The page is dirty, which means it was budgeted twice: | |
269 | * o first time the budget was allocated by the task which | |
270 | * made the page dirty and set the PG_private flag; | |
271 | * o and then we budgeted for it for the second time at the | |
272 | * very beginning of this function. | |
273 | * | |
274 | * So what we have to do is to release the page budget we | |
275 | * allocated. | |
276 | */ | |
277 | release_new_page_budget(c); | |
278 | else if (!PageChecked(page)) | |
279 | /* | |
280 | * We are changing a page which already exists on the media. | |
281 | * This means that changing the page does not make the amount | |
282 | * of indexing information larger, and this part of the budget | |
283 | * which we have already acquired may be released. | |
284 | */ | |
285 | ubifs_convert_page_budget(c); | |
286 | ||
287 | if (appending) { | |
288 | struct ubifs_inode *ui = ubifs_inode(inode); | |
289 | ||
290 | /* | |
291 | * 'ubifs_write_end()' is optimized from the fast-path part of | |
292 | * 'ubifs_write_begin()' and expects the @ui_mutex to be locked | |
293 | * if data is appended. | |
294 | */ | |
295 | mutex_lock(&ui->ui_mutex); | |
296 | if (ui->dirty) | |
297 | /* | |
298 | * The inode is dirty already, so we may free the | |
299 | * budget we allocated. | |
300 | */ | |
301 | ubifs_release_dirty_inode_budget(c, ui); | |
302 | } | |
303 | ||
304 | *pagep = page; | |
305 | return 0; | |
306 | } | |
307 | ||
308 | /** | |
309 | * allocate_budget - allocate budget for 'ubifs_write_begin()'. | |
310 | * @c: UBIFS file-system description object | |
311 | * @page: page to allocate budget for | |
312 | * @ui: UBIFS inode object the page belongs to | |
313 | * @appending: non-zero if the page is appended | |
314 | * | |
315 | * This is a helper function for 'ubifs_write_begin()' which allocates budget | |
316 | * for the operation. The budget is allocated differently depending on whether | |
317 | * this is appending, whether the page is dirty or not, and so on. This | |
318 | * function leaves the @ui->ui_mutex locked in case of appending. Returns zero | |
319 | * in case of success and %-ENOSPC in case of failure. | |
320 | */ | |
321 | static int allocate_budget(struct ubifs_info *c, struct page *page, | |
322 | struct ubifs_inode *ui, int appending) | |
323 | { | |
324 | struct ubifs_budget_req req = { .fast = 1 }; | |
325 | ||
326 | if (PagePrivate(page)) { | |
327 | if (!appending) | |
328 | /* | |
329 | * The page is dirty and we are not appending, which | |
330 | * means no budget is needed at all. | |
331 | */ | |
332 | return 0; | |
333 | ||
334 | mutex_lock(&ui->ui_mutex); | |
335 | if (ui->dirty) | |
336 | /* | |
337 | * The page is dirty and we are appending, so the inode | |
338 | * has to be marked as dirty. However, it is already | |
339 | * dirty, so we do not need any budget. We may return, | |
340 | * but @ui->ui_mutex hast to be left locked because we | |
341 | * should prevent write-back from flushing the inode | |
342 | * and freeing the budget. The lock will be released in | |
343 | * 'ubifs_write_end()'. | |
344 | */ | |
345 | return 0; | |
346 | ||
347 | /* | |
348 | * The page is dirty, we are appending, the inode is clean, so | |
349 | * we need to budget the inode change. | |
350 | */ | |
351 | req.dirtied_ino = 1; | |
352 | } else { | |
353 | if (PageChecked(page)) | |
354 | /* | |
355 | * The page corresponds to a hole and does not | |
356 | * exist on the media. So changing it makes | |
357 | * make the amount of indexing information | |
358 | * larger, and we have to budget for a new | |
359 | * page. | |
360 | */ | |
361 | req.new_page = 1; | |
362 | else | |
363 | /* | |
364 | * Not a hole, the change will not add any new | |
365 | * indexing information, budget for page | |
366 | * change. | |
367 | */ | |
368 | req.dirtied_page = 1; | |
369 | ||
370 | if (appending) { | |
371 | mutex_lock(&ui->ui_mutex); | |
372 | if (!ui->dirty) | |
373 | /* | |
374 | * The inode is clean but we will have to mark | |
375 | * it as dirty because we are appending. This | |
376 | * needs a budget. | |
377 | */ | |
378 | req.dirtied_ino = 1; | |
379 | } | |
380 | } | |
381 | ||
382 | return ubifs_budget_space(c, &req); | |
383 | } | |
384 | ||
385 | /* | |
386 | * This function is called when a page of data is going to be written. Since | |
387 | * the page of data will not necessarily go to the flash straight away, UBIFS | |
388 | * has to reserve space on the media for it, which is done by means of | |
389 | * budgeting. | |
390 | * | |
391 | * This is the hot-path of the file-system and we are trying to optimize it as | |
392 | * much as possible. For this reasons it is split on 2 parts - slow and fast. | |
393 | * | |
394 | * There many budgeting cases: | |
395 | * o a new page is appended - we have to budget for a new page and for | |
396 | * changing the inode; however, if the inode is already dirty, there is | |
397 | * no need to budget for it; | |
398 | * o an existing clean page is changed - we have budget for it; if the page | |
399 | * does not exist on the media (a hole), we have to budget for a new | |
400 | * page; otherwise, we may budget for changing an existing page; the | |
401 | * difference between these cases is that changing an existing page does | |
402 | * not introduce anything new to the FS indexing information, so it does | |
403 | * not grow, and smaller budget is acquired in this case; | |
404 | * o an existing dirty page is changed - no need to budget at all, because | |
405 | * the page budget has been acquired by earlier, when the page has been | |
406 | * marked dirty. | |
407 | * | |
408 | * UBIFS budgeting sub-system may force write-back if it thinks there is no | |
409 | * space to reserve. This imposes some locking restrictions and makes it | |
410 | * impossible to take into account the above cases, and makes it impossible to | |
411 | * optimize budgeting. | |
412 | * | |
413 | * The solution for this is that the fast path of 'ubifs_write_begin()' assumes | |
414 | * there is a plenty of flash space and the budget will be acquired quickly, | |
415 | * without forcing write-back. The slow path does not make this assumption. | |
416 | */ | |
417 | static int ubifs_write_begin(struct file *file, struct address_space *mapping, | |
418 | loff_t pos, unsigned len, unsigned flags, | |
419 | struct page **pagep, void **fsdata) | |
420 | { | |
421 | struct inode *inode = mapping->host; | |
422 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
423 | struct ubifs_inode *ui = ubifs_inode(inode); | |
424 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
425 | int uninitialized_var(err), appending = !!(pos + len > inode->i_size); | |
426 | struct page *page; | |
427 | ||
428 | ||
429 | ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size); | |
430 | ||
431 | if (unlikely(c->ro_media)) | |
432 | return -EROFS; | |
433 | ||
434 | /* Try out the fast-path part first */ | |
435 | page = __grab_cache_page(mapping, index); | |
436 | if (unlikely(!page)) | |
437 | return -ENOMEM; | |
438 | ||
439 | if (!PageUptodate(page)) { | |
440 | /* The page is not loaded from the flash */ | |
441 | if (!(pos & PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) | |
442 | /* | |
443 | * We change whole page so no need to load it. But we | |
444 | * have to set the @PG_checked flag to make the further | |
445 | * code the page is new. This might be not true, but it | |
446 | * is better to budget more that to read the page from | |
447 | * the media. | |
448 | */ | |
449 | SetPageChecked(page); | |
450 | else { | |
451 | err = do_readpage(page); | |
452 | if (err) { | |
453 | unlock_page(page); | |
454 | page_cache_release(page); | |
455 | return err; | |
456 | } | |
457 | } | |
458 | ||
459 | SetPageUptodate(page); | |
460 | ClearPageError(page); | |
461 | } | |
462 | ||
463 | err = allocate_budget(c, page, ui, appending); | |
464 | if (unlikely(err)) { | |
465 | ubifs_assert(err == -ENOSPC); | |
466 | /* | |
467 | * Budgeting failed which means it would have to force | |
468 | * write-back but didn't, because we set the @fast flag in the | |
469 | * request. Write-back cannot be done now, while we have the | |
470 | * page locked, because it would deadlock. Unlock and free | |
471 | * everything and fall-back to slow-path. | |
472 | */ | |
473 | if (appending) { | |
474 | ubifs_assert(mutex_is_locked(&ui->ui_mutex)); | |
475 | mutex_unlock(&ui->ui_mutex); | |
476 | } | |
477 | unlock_page(page); | |
478 | page_cache_release(page); | |
479 | ||
480 | return write_begin_slow(mapping, pos, len, pagep); | |
481 | } | |
482 | ||
483 | /* | |
484 | * Whee, we aquired budgeting quickly - without involving | |
485 | * garbage-collection, committing or forceing write-back. We return | |
486 | * with @ui->ui_mutex locked if we are appending pages, and unlocked | |
487 | * otherwise. This is an optimization (slightly hacky though). | |
488 | */ | |
489 | *pagep = page; | |
490 | return 0; | |
491 | ||
492 | } | |
493 | ||
494 | /** | |
495 | * cancel_budget - cancel budget. | |
496 | * @c: UBIFS file-system description object | |
497 | * @page: page to cancel budget for | |
498 | * @ui: UBIFS inode object the page belongs to | |
499 | * @appending: non-zero if the page is appended | |
500 | * | |
501 | * This is a helper function for a page write operation. It unlocks the | |
502 | * @ui->ui_mutex in case of appending. | |
503 | */ | |
504 | static void cancel_budget(struct ubifs_info *c, struct page *page, | |
505 | struct ubifs_inode *ui, int appending) | |
506 | { | |
507 | if (appending) { | |
508 | if (!ui->dirty) | |
509 | ubifs_release_dirty_inode_budget(c, ui); | |
510 | mutex_unlock(&ui->ui_mutex); | |
511 | } | |
512 | if (!PagePrivate(page)) { | |
513 | if (PageChecked(page)) | |
514 | release_new_page_budget(c); | |
515 | else | |
516 | release_existing_page_budget(c); | |
517 | } | |
518 | } | |
519 | ||
520 | static int ubifs_write_end(struct file *file, struct address_space *mapping, | |
521 | loff_t pos, unsigned len, unsigned copied, | |
522 | struct page *page, void *fsdata) | |
523 | { | |
524 | struct inode *inode = mapping->host; | |
525 | struct ubifs_inode *ui = ubifs_inode(inode); | |
526 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
527 | loff_t end_pos = pos + len; | |
528 | int appending = !!(end_pos > inode->i_size); | |
529 | ||
530 | dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld", | |
531 | inode->i_ino, pos, page->index, len, copied, inode->i_size); | |
532 | ||
533 | if (unlikely(copied < len && len == PAGE_CACHE_SIZE)) { | |
534 | /* | |
535 | * VFS copied less data to the page that it intended and | |
536 | * declared in its '->write_begin()' call via the @len | |
537 | * argument. If the page was not up-to-date, and @len was | |
538 | * @PAGE_CACHE_SIZE, the 'ubifs_write_begin()' function did | |
539 | * not load it from the media (for optimization reasons). This | |
540 | * means that part of the page contains garbage. So read the | |
541 | * page now. | |
542 | */ | |
543 | dbg_gen("copied %d instead of %d, read page and repeat", | |
544 | copied, len); | |
545 | cancel_budget(c, page, ui, appending); | |
546 | ||
547 | /* | |
548 | * Return 0 to force VFS to repeat the whole operation, or the | |
549 | * error code if 'do_readpage()' failes. | |
550 | */ | |
551 | copied = do_readpage(page); | |
552 | goto out; | |
553 | } | |
554 | ||
555 | if (!PagePrivate(page)) { | |
556 | SetPagePrivate(page); | |
557 | atomic_long_inc(&c->dirty_pg_cnt); | |
558 | __set_page_dirty_nobuffers(page); | |
559 | } | |
560 | ||
561 | if (appending) { | |
562 | i_size_write(inode, end_pos); | |
563 | ui->ui_size = end_pos; | |
564 | /* | |
565 | * Note, we do not set @I_DIRTY_PAGES (which means that the | |
566 | * inode has dirty pages), this has been done in | |
567 | * '__set_page_dirty_nobuffers()'. | |
568 | */ | |
569 | __mark_inode_dirty(inode, I_DIRTY_DATASYNC); | |
570 | ubifs_assert(mutex_is_locked(&ui->ui_mutex)); | |
571 | mutex_unlock(&ui->ui_mutex); | |
572 | } | |
573 | ||
574 | out: | |
575 | unlock_page(page); | |
576 | page_cache_release(page); | |
577 | return copied; | |
578 | } | |
579 | ||
580 | static int ubifs_readpage(struct file *file, struct page *page) | |
581 | { | |
582 | do_readpage(page); | |
583 | unlock_page(page); | |
584 | return 0; | |
585 | } | |
586 | ||
587 | static int do_writepage(struct page *page, int len) | |
588 | { | |
589 | int err = 0, i, blen; | |
590 | unsigned int block; | |
591 | void *addr; | |
592 | union ubifs_key key; | |
593 | struct inode *inode = page->mapping->host; | |
594 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
595 | ||
596 | #ifdef UBIFS_DEBUG | |
597 | spin_lock(&ui->ui_lock); | |
598 | ubifs_assert(page->index <= ui->synced_i_size << PAGE_CACHE_SIZE); | |
599 | spin_unlock(&ui->ui_lock); | |
600 | #endif | |
601 | ||
602 | /* Update radix tree tags */ | |
603 | set_page_writeback(page); | |
604 | ||
605 | addr = kmap(page); | |
606 | block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; | |
607 | i = 0; | |
608 | while (len) { | |
609 | blen = min_t(int, len, UBIFS_BLOCK_SIZE); | |
610 | data_key_init(c, &key, inode->i_ino, block); | |
611 | err = ubifs_jnl_write_data(c, inode, &key, addr, blen); | |
612 | if (err) | |
613 | break; | |
614 | if (++i >= UBIFS_BLOCKS_PER_PAGE) | |
615 | break; | |
616 | block += 1; | |
617 | addr += blen; | |
618 | len -= blen; | |
619 | } | |
620 | if (err) { | |
621 | SetPageError(page); | |
622 | ubifs_err("cannot write page %lu of inode %lu, error %d", | |
623 | page->index, inode->i_ino, err); | |
624 | ubifs_ro_mode(c, err); | |
625 | } | |
626 | ||
627 | ubifs_assert(PagePrivate(page)); | |
628 | if (PageChecked(page)) | |
629 | release_new_page_budget(c); | |
630 | else | |
631 | release_existing_page_budget(c); | |
632 | ||
633 | atomic_long_dec(&c->dirty_pg_cnt); | |
634 | ClearPagePrivate(page); | |
635 | ClearPageChecked(page); | |
636 | ||
637 | kunmap(page); | |
638 | unlock_page(page); | |
639 | end_page_writeback(page); | |
640 | return err; | |
641 | } | |
642 | ||
643 | /* | |
644 | * When writing-back dirty inodes, VFS first writes-back pages belonging to the | |
645 | * inode, then the inode itself. For UBIFS this may cause a problem. Consider a | |
646 | * situation when a we have an inode with size 0, then a megabyte of data is | |
647 | * appended to the inode, then write-back starts and flushes some amount of the | |
648 | * dirty pages, the journal becomes full, commit happens and finishes, and then | |
649 | * an unclean reboot happens. When the file system is mounted next time, the | |
650 | * inode size would still be 0, but there would be many pages which are beyond | |
651 | * the inode size, they would be indexed and consume flash space. Because the | |
652 | * journal has been committed, the replay would not be able to detect this | |
653 | * situation and correct the inode size. This means UBIFS would have to scan | |
654 | * whole index and correct all inode sizes, which is long an unacceptable. | |
655 | * | |
656 | * To prevent situations like this, UBIFS writes pages back only if they are | |
657 | * within last synchronized inode size, i.e. the the size which has been | |
658 | * written to the flash media last time. Otherwise, UBIFS forces inode | |
659 | * write-back, thus making sure the on-flash inode contains current inode size, | |
660 | * and then keeps writing pages back. | |
661 | * | |
662 | * Some locking issues explanation. 'ubifs_writepage()' first is called with | |
663 | * the page locked, and it locks @ui_mutex. However, write-back does take inode | |
664 | * @i_mutex, which means other VFS operations may be run on this inode at the | |
665 | * same time. And the problematic one is truncation to smaller size, from where | |
666 | * we have to call 'vmtruncate()', which first changes @inode->i_size, then | |
667 | * drops the truncated pages. And while dropping the pages, it takes the page | |
668 | * lock. This means that 'do_truncation()' cannot call 'vmtruncate()' with | |
669 | * @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'. This | |
670 | * means that @inode->i_size is changed while @ui_mutex is unlocked. | |
671 | * | |
672 | * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond | |
673 | * inode size. How do we do this if @inode->i_size may became smaller while we | |
674 | * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the | |
675 | * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size | |
676 | * internally and updates it under @ui_mutex. | |
677 | * | |
678 | * Q: why we do not worry that if we race with truncation, we may end up with a | |
679 | * situation when the inode is truncated while we are in the middle of | |
680 | * 'do_writepage()', so we do write beyond inode size? | |
681 | * A: If we are in the middle of 'do_writepage()', truncation would be locked | |
682 | * on the page lock and it would not write the truncated inode node to the | |
683 | * journal before we have finished. | |
684 | */ | |
685 | static int ubifs_writepage(struct page *page, struct writeback_control *wbc) | |
686 | { | |
687 | struct inode *inode = page->mapping->host; | |
688 | struct ubifs_inode *ui = ubifs_inode(inode); | |
689 | loff_t i_size = i_size_read(inode), synced_i_size; | |
690 | pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
691 | int err, len = i_size & (PAGE_CACHE_SIZE - 1); | |
692 | void *kaddr; | |
693 | ||
694 | dbg_gen("ino %lu, pg %lu, pg flags %#lx", | |
695 | inode->i_ino, page->index, page->flags); | |
696 | ubifs_assert(PagePrivate(page)); | |
697 | ||
698 | /* Is the page fully outside @i_size? (truncate in progress) */ | |
699 | if (page->index > end_index || (page->index == end_index && !len)) { | |
700 | err = 0; | |
701 | goto out_unlock; | |
702 | } | |
703 | ||
704 | spin_lock(&ui->ui_lock); | |
705 | synced_i_size = ui->synced_i_size; | |
706 | spin_unlock(&ui->ui_lock); | |
707 | ||
708 | /* Is the page fully inside @i_size? */ | |
709 | if (page->index < end_index) { | |
710 | if (page->index >= synced_i_size >> PAGE_CACHE_SHIFT) { | |
711 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
712 | if (err) | |
713 | goto out_unlock; | |
714 | /* | |
715 | * The inode has been written, but the write-buffer has | |
716 | * not been synchronized, so in case of an unclean | |
717 | * reboot we may end up with some pages beyond inode | |
718 | * size, but they would be in the journal (because | |
719 | * commit flushes write buffers) and recovery would deal | |
720 | * with this. | |
721 | */ | |
722 | } | |
723 | return do_writepage(page, PAGE_CACHE_SIZE); | |
724 | } | |
725 | ||
726 | /* | |
727 | * The page straddles @i_size. It must be zeroed out on each and every | |
728 | * writepage invocation because it may be mmapped. "A file is mapped | |
729 | * in multiples of the page size. For a file that is not a multiple of | |
730 | * the page size, the remaining memory is zeroed when mapped, and | |
731 | * writes to that region are not written out to the file." | |
732 | */ | |
733 | kaddr = kmap_atomic(page, KM_USER0); | |
734 | memset(kaddr + len, 0, PAGE_CACHE_SIZE - len); | |
735 | flush_dcache_page(page); | |
736 | kunmap_atomic(kaddr, KM_USER0); | |
737 | ||
738 | if (i_size > synced_i_size) { | |
739 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
740 | if (err) | |
741 | goto out_unlock; | |
742 | } | |
743 | ||
744 | return do_writepage(page, len); | |
745 | ||
746 | out_unlock: | |
747 | unlock_page(page); | |
748 | return err; | |
749 | } | |
750 | ||
751 | /** | |
752 | * do_attr_changes - change inode attributes. | |
753 | * @inode: inode to change attributes for | |
754 | * @attr: describes attributes to change | |
755 | */ | |
756 | static void do_attr_changes(struct inode *inode, const struct iattr *attr) | |
757 | { | |
758 | if (attr->ia_valid & ATTR_UID) | |
759 | inode->i_uid = attr->ia_uid; | |
760 | if (attr->ia_valid & ATTR_GID) | |
761 | inode->i_gid = attr->ia_gid; | |
762 | if (attr->ia_valid & ATTR_ATIME) | |
763 | inode->i_atime = timespec_trunc(attr->ia_atime, | |
764 | inode->i_sb->s_time_gran); | |
765 | if (attr->ia_valid & ATTR_MTIME) | |
766 | inode->i_mtime = timespec_trunc(attr->ia_mtime, | |
767 | inode->i_sb->s_time_gran); | |
768 | if (attr->ia_valid & ATTR_CTIME) | |
769 | inode->i_ctime = timespec_trunc(attr->ia_ctime, | |
770 | inode->i_sb->s_time_gran); | |
771 | if (attr->ia_valid & ATTR_MODE) { | |
772 | umode_t mode = attr->ia_mode; | |
773 | ||
774 | if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) | |
775 | mode &= ~S_ISGID; | |
776 | inode->i_mode = mode; | |
777 | } | |
778 | } | |
779 | ||
780 | /** | |
781 | * do_truncation - truncate an inode. | |
782 | * @c: UBIFS file-system description object | |
783 | * @inode: inode to truncate | |
784 | * @attr: inode attribute changes description | |
785 | * | |
786 | * This function implements VFS '->setattr()' call when the inode is truncated | |
787 | * to a smaller size. Returns zero in case of success and a negative error code | |
788 | * in case of failure. | |
789 | */ | |
790 | static int do_truncation(struct ubifs_info *c, struct inode *inode, | |
791 | const struct iattr *attr) | |
792 | { | |
793 | int err; | |
794 | struct ubifs_budget_req req; | |
795 | loff_t old_size = inode->i_size, new_size = attr->ia_size; | |
796 | int offset = new_size & (UBIFS_BLOCK_SIZE - 1); | |
797 | struct ubifs_inode *ui = ubifs_inode(inode); | |
798 | ||
799 | dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size); | |
800 | memset(&req, 0, sizeof(struct ubifs_budget_req)); | |
801 | ||
802 | /* | |
803 | * If this is truncation to a smaller size, and we do not truncate on a | |
804 | * block boundary, budget for changing one data block, because the last | |
805 | * block will be re-written. | |
806 | */ | |
807 | if (new_size & (UBIFS_BLOCK_SIZE - 1)) | |
808 | req.dirtied_page = 1; | |
809 | ||
810 | req.dirtied_ino = 1; | |
811 | /* A funny way to budget for truncation node */ | |
812 | req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ; | |
813 | err = ubifs_budget_space(c, &req); | |
814 | if (err) | |
815 | return err; | |
816 | ||
817 | err = vmtruncate(inode, new_size); | |
818 | if (err) | |
819 | goto out_budg; | |
820 | ||
821 | if (offset) { | |
822 | pgoff_t index = new_size >> PAGE_CACHE_SHIFT; | |
823 | struct page *page; | |
824 | ||
825 | page = find_lock_page(inode->i_mapping, index); | |
826 | if (page) { | |
827 | if (PageDirty(page)) { | |
828 | /* | |
829 | * 'ubifs_jnl_truncate()' will try to truncate | |
830 | * the last data node, but it contains | |
831 | * out-of-date data because the page is dirty. | |
832 | * Write the page now, so that | |
833 | * 'ubifs_jnl_truncate()' will see an already | |
834 | * truncated (and up to date) data node. | |
835 | */ | |
836 | ubifs_assert(PagePrivate(page)); | |
837 | ||
838 | clear_page_dirty_for_io(page); | |
839 | if (UBIFS_BLOCKS_PER_PAGE_SHIFT) | |
840 | offset = new_size & | |
841 | (PAGE_CACHE_SIZE - 1); | |
842 | err = do_writepage(page, offset); | |
843 | page_cache_release(page); | |
844 | if (err) | |
845 | goto out_budg; | |
846 | /* | |
847 | * We could now tell 'ubifs_jnl_truncate()' not | |
848 | * to read the last block. | |
849 | */ | |
850 | } else { | |
851 | /* | |
852 | * We could 'kmap()' the page and pass the data | |
853 | * to 'ubifs_jnl_truncate()' to save it from | |
854 | * having to read it. | |
855 | */ | |
856 | unlock_page(page); | |
857 | page_cache_release(page); | |
858 | } | |
859 | } | |
860 | } | |
861 | ||
862 | mutex_lock(&ui->ui_mutex); | |
863 | ui->ui_size = inode->i_size; | |
864 | /* Truncation changes inode [mc]time */ | |
865 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
866 | /* The other attributes may be changed at the same time as well */ | |
867 | do_attr_changes(inode, attr); | |
868 | ||
869 | err = ubifs_jnl_truncate(c, inode, old_size, new_size); | |
870 | mutex_unlock(&ui->ui_mutex); | |
871 | out_budg: | |
872 | ubifs_release_budget(c, &req); | |
873 | return err; | |
874 | } | |
875 | ||
876 | /** | |
877 | * do_setattr - change inode attributes. | |
878 | * @c: UBIFS file-system description object | |
879 | * @inode: inode to change attributes for | |
880 | * @attr: inode attribute changes description | |
881 | * | |
882 | * This function implements VFS '->setattr()' call for all cases except | |
883 | * truncations to smaller size. Returns zero in case of success and a negative | |
884 | * error code in case of failure. | |
885 | */ | |
886 | static int do_setattr(struct ubifs_info *c, struct inode *inode, | |
887 | const struct iattr *attr) | |
888 | { | |
889 | int err, release; | |
890 | loff_t new_size = attr->ia_size; | |
891 | struct ubifs_inode *ui = ubifs_inode(inode); | |
892 | struct ubifs_budget_req req = { .dirtied_ino = 1, | |
893 | .dirtied_ino_d = ui->data_len }; | |
894 | ||
895 | err = ubifs_budget_space(c, &req); | |
896 | if (err) | |
897 | return err; | |
898 | ||
899 | if (attr->ia_valid & ATTR_SIZE) { | |
900 | dbg_gen("size %lld -> %lld", inode->i_size, new_size); | |
901 | err = vmtruncate(inode, new_size); | |
902 | if (err) | |
903 | goto out; | |
904 | } | |
905 | ||
906 | mutex_lock(&ui->ui_mutex); | |
907 | if (attr->ia_valid & ATTR_SIZE) { | |
908 | /* Truncation changes inode [mc]time */ | |
909 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
910 | /* 'vmtruncate()' changed @i_size, update @ui_size */ | |
911 | ui->ui_size = inode->i_size; | |
912 | } | |
913 | ||
914 | do_attr_changes(inode, attr); | |
915 | ||
916 | release = ui->dirty; | |
917 | if (attr->ia_valid & ATTR_SIZE) | |
918 | /* | |
919 | * Inode length changed, so we have to make sure | |
920 | * @I_DIRTY_DATASYNC is set. | |
921 | */ | |
922 | __mark_inode_dirty(inode, I_DIRTY_SYNC | I_DIRTY_DATASYNC); | |
923 | else | |
924 | mark_inode_dirty_sync(inode); | |
925 | mutex_unlock(&ui->ui_mutex); | |
926 | ||
927 | if (release) | |
928 | ubifs_release_budget(c, &req); | |
929 | if (IS_SYNC(inode)) | |
930 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
931 | return err; | |
932 | ||
933 | out: | |
934 | ubifs_release_budget(c, &req); | |
935 | return err; | |
936 | } | |
937 | ||
938 | int ubifs_setattr(struct dentry *dentry, struct iattr *attr) | |
939 | { | |
940 | int err; | |
941 | struct inode *inode = dentry->d_inode; | |
942 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
943 | ||
7d32c2bb AB |
944 | dbg_gen("ino %lu, mode %#x, ia_valid %#x", |
945 | inode->i_ino, inode->i_mode, attr->ia_valid); | |
1e51764a AB |
946 | err = inode_change_ok(inode, attr); |
947 | if (err) | |
948 | return err; | |
949 | ||
950 | err = dbg_check_synced_i_size(inode); | |
951 | if (err) | |
952 | return err; | |
953 | ||
954 | if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size) | |
955 | /* Truncation to a smaller size */ | |
956 | err = do_truncation(c, inode, attr); | |
957 | else | |
958 | err = do_setattr(c, inode, attr); | |
959 | ||
960 | return err; | |
961 | } | |
962 | ||
963 | static void ubifs_invalidatepage(struct page *page, unsigned long offset) | |
964 | { | |
965 | struct inode *inode = page->mapping->host; | |
966 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
967 | ||
968 | ubifs_assert(PagePrivate(page)); | |
969 | if (offset) | |
970 | /* Partial page remains dirty */ | |
971 | return; | |
972 | ||
973 | if (PageChecked(page)) | |
974 | release_new_page_budget(c); | |
975 | else | |
976 | release_existing_page_budget(c); | |
977 | ||
978 | atomic_long_dec(&c->dirty_pg_cnt); | |
979 | ClearPagePrivate(page); | |
980 | ClearPageChecked(page); | |
981 | } | |
982 | ||
983 | static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd) | |
984 | { | |
985 | struct ubifs_inode *ui = ubifs_inode(dentry->d_inode); | |
986 | ||
987 | nd_set_link(nd, ui->data); | |
988 | return NULL; | |
989 | } | |
990 | ||
991 | int ubifs_fsync(struct file *file, struct dentry *dentry, int datasync) | |
992 | { | |
993 | struct inode *inode = dentry->d_inode; | |
994 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
995 | int err; | |
996 | ||
997 | dbg_gen("syncing inode %lu", inode->i_ino); | |
998 | ||
999 | /* | |
1000 | * VFS has already synchronized dirty pages for this inode. Synchronize | |
1001 | * the inode unless this is a 'datasync()' call. | |
1002 | */ | |
1003 | if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) { | |
1004 | err = inode->i_sb->s_op->write_inode(inode, 1); | |
1005 | if (err) | |
1006 | return err; | |
1007 | } | |
1008 | ||
1009 | /* | |
1010 | * Nodes related to this inode may still sit in a write-buffer. Flush | |
1011 | * them. | |
1012 | */ | |
1013 | err = ubifs_sync_wbufs_by_inode(c, inode); | |
1014 | if (err) | |
1015 | return err; | |
1016 | ||
1017 | return 0; | |
1018 | } | |
1019 | ||
1020 | /** | |
1021 | * mctime_update_needed - check if mtime or ctime update is needed. | |
1022 | * @inode: the inode to do the check for | |
1023 | * @now: current time | |
1024 | * | |
1025 | * This helper function checks if the inode mtime/ctime should be updated or | |
1026 | * not. If current values of the time-stamps are within the UBIFS inode time | |
1027 | * granularity, they are not updated. This is an optimization. | |
1028 | */ | |
1029 | static inline int mctime_update_needed(const struct inode *inode, | |
1030 | const struct timespec *now) | |
1031 | { | |
1032 | if (!timespec_equal(&inode->i_mtime, now) || | |
1033 | !timespec_equal(&inode->i_ctime, now)) | |
1034 | return 1; | |
1035 | return 0; | |
1036 | } | |
1037 | ||
1038 | /** | |
1039 | * update_ctime - update mtime and ctime of an inode. | |
1040 | * @c: UBIFS file-system description object | |
1041 | * @inode: inode to update | |
1042 | * | |
1043 | * This function updates mtime and ctime of the inode if it is not equivalent to | |
1044 | * current time. Returns zero in case of success and a negative error code in | |
1045 | * case of failure. | |
1046 | */ | |
1047 | static int update_mctime(struct ubifs_info *c, struct inode *inode) | |
1048 | { | |
1049 | struct timespec now = ubifs_current_time(inode); | |
1050 | struct ubifs_inode *ui = ubifs_inode(inode); | |
1051 | ||
1052 | if (mctime_update_needed(inode, &now)) { | |
1053 | int err, release; | |
1054 | struct ubifs_budget_req req = { .dirtied_ino = 1, | |
1055 | .dirtied_ino_d = ui->data_len }; | |
1056 | ||
1057 | err = ubifs_budget_space(c, &req); | |
1058 | if (err) | |
1059 | return err; | |
1060 | ||
1061 | mutex_lock(&ui->ui_mutex); | |
1062 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
1063 | release = ui->dirty; | |
1064 | mark_inode_dirty_sync(inode); | |
1065 | mutex_unlock(&ui->ui_mutex); | |
1066 | if (release) | |
1067 | ubifs_release_budget(c, &req); | |
1068 | } | |
1069 | ||
1070 | return 0; | |
1071 | } | |
1072 | ||
1073 | static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov, | |
1074 | unsigned long nr_segs, loff_t pos) | |
1075 | { | |
1076 | int err; | |
1077 | ssize_t ret; | |
1078 | struct inode *inode = iocb->ki_filp->f_mapping->host; | |
1079 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
1080 | ||
1081 | err = update_mctime(c, inode); | |
1082 | if (err) | |
1083 | return err; | |
1084 | ||
1085 | ret = generic_file_aio_write(iocb, iov, nr_segs, pos); | |
1086 | if (ret < 0) | |
1087 | return ret; | |
1088 | ||
1089 | if (ret > 0 && (IS_SYNC(inode) || iocb->ki_filp->f_flags & O_SYNC)) { | |
1090 | err = ubifs_sync_wbufs_by_inode(c, inode); | |
1091 | if (err) | |
1092 | return err; | |
1093 | } | |
1094 | ||
1095 | return ret; | |
1096 | } | |
1097 | ||
1098 | static int ubifs_set_page_dirty(struct page *page) | |
1099 | { | |
1100 | int ret; | |
1101 | ||
1102 | ret = __set_page_dirty_nobuffers(page); | |
1103 | /* | |
1104 | * An attempt to dirty a page without budgeting for it - should not | |
1105 | * happen. | |
1106 | */ | |
1107 | ubifs_assert(ret == 0); | |
1108 | return ret; | |
1109 | } | |
1110 | ||
1111 | static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags) | |
1112 | { | |
1113 | /* | |
1114 | * An attempt to release a dirty page without budgeting for it - should | |
1115 | * not happen. | |
1116 | */ | |
1117 | if (PageWriteback(page)) | |
1118 | return 0; | |
1119 | ubifs_assert(PagePrivate(page)); | |
1120 | ubifs_assert(0); | |
1121 | ClearPagePrivate(page); | |
1122 | ClearPageChecked(page); | |
1123 | return 1; | |
1124 | } | |
1125 | ||
1126 | /* | |
1127 | * mmap()d file has taken write protection fault and is being made | |
1128 | * writable. UBIFS must ensure page is budgeted for. | |
1129 | */ | |
1130 | static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page) | |
1131 | { | |
1132 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; | |
1133 | struct ubifs_info *c = inode->i_sb->s_fs_info; | |
1134 | struct timespec now = ubifs_current_time(inode); | |
1135 | struct ubifs_budget_req req = { .new_page = 1 }; | |
1136 | int err, update_time; | |
1137 | ||
1138 | dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index, | |
1139 | i_size_read(inode)); | |
1140 | ubifs_assert(!(inode->i_sb->s_flags & MS_RDONLY)); | |
1141 | ||
1142 | if (unlikely(c->ro_media)) | |
1143 | return -EROFS; | |
1144 | ||
1145 | /* | |
1146 | * We have not locked @page so far so we may budget for changing the | |
1147 | * page. Note, we cannot do this after we locked the page, because | |
1148 | * budgeting may cause write-back which would cause deadlock. | |
1149 | * | |
1150 | * At the moment we do not know whether the page is dirty or not, so we | |
1151 | * assume that it is not and budget for a new page. We could look at | |
1152 | * the @PG_private flag and figure this out, but we may race with write | |
1153 | * back and the page state may change by the time we lock it, so this | |
1154 | * would need additional care. We do not bother with this at the | |
1155 | * moment, although it might be good idea to do. Instead, we allocate | |
1156 | * budget for a new page and amend it later on if the page was in fact | |
1157 | * dirty. | |
1158 | * | |
1159 | * The budgeting-related logic of this function is similar to what we | |
1160 | * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there | |
1161 | * for more comments. | |
1162 | */ | |
1163 | update_time = mctime_update_needed(inode, &now); | |
1164 | if (update_time) | |
1165 | /* | |
1166 | * We have to change inode time stamp which requires extra | |
1167 | * budgeting. | |
1168 | */ | |
1169 | req.dirtied_ino = 1; | |
1170 | ||
1171 | err = ubifs_budget_space(c, &req); | |
1172 | if (unlikely(err)) { | |
1173 | if (err == -ENOSPC) | |
1174 | ubifs_warn("out of space for mmapped file " | |
1175 | "(inode number %lu)", inode->i_ino); | |
1176 | return err; | |
1177 | } | |
1178 | ||
1179 | lock_page(page); | |
1180 | if (unlikely(page->mapping != inode->i_mapping || | |
1181 | page_offset(page) > i_size_read(inode))) { | |
1182 | /* Page got truncated out from underneath us */ | |
1183 | err = -EINVAL; | |
1184 | goto out_unlock; | |
1185 | } | |
1186 | ||
1187 | if (PagePrivate(page)) | |
1188 | release_new_page_budget(c); | |
1189 | else { | |
1190 | if (!PageChecked(page)) | |
1191 | ubifs_convert_page_budget(c); | |
1192 | SetPagePrivate(page); | |
1193 | atomic_long_inc(&c->dirty_pg_cnt); | |
1194 | __set_page_dirty_nobuffers(page); | |
1195 | } | |
1196 | ||
1197 | if (update_time) { | |
1198 | int release; | |
1199 | struct ubifs_inode *ui = ubifs_inode(inode); | |
1200 | ||
1201 | mutex_lock(&ui->ui_mutex); | |
1202 | inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); | |
1203 | release = ui->dirty; | |
1204 | mark_inode_dirty_sync(inode); | |
1205 | mutex_unlock(&ui->ui_mutex); | |
1206 | if (release) | |
1207 | ubifs_release_dirty_inode_budget(c, ui); | |
1208 | } | |
1209 | ||
1210 | unlock_page(page); | |
1211 | return 0; | |
1212 | ||
1213 | out_unlock: | |
1214 | unlock_page(page); | |
1215 | ubifs_release_budget(c, &req); | |
1216 | return err; | |
1217 | } | |
1218 | ||
1219 | static struct vm_operations_struct ubifs_file_vm_ops = { | |
1220 | .fault = filemap_fault, | |
1221 | .page_mkwrite = ubifs_vm_page_mkwrite, | |
1222 | }; | |
1223 | ||
1224 | static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma) | |
1225 | { | |
1226 | int err; | |
1227 | ||
1228 | /* 'generic_file_mmap()' takes care of NOMMU case */ | |
1229 | err = generic_file_mmap(file, vma); | |
1230 | if (err) | |
1231 | return err; | |
1232 | vma->vm_ops = &ubifs_file_vm_ops; | |
1233 | return 0; | |
1234 | } | |
1235 | ||
1236 | struct address_space_operations ubifs_file_address_operations = { | |
1237 | .readpage = ubifs_readpage, | |
1238 | .writepage = ubifs_writepage, | |
1239 | .write_begin = ubifs_write_begin, | |
1240 | .write_end = ubifs_write_end, | |
1241 | .invalidatepage = ubifs_invalidatepage, | |
1242 | .set_page_dirty = ubifs_set_page_dirty, | |
1243 | .releasepage = ubifs_releasepage, | |
1244 | }; | |
1245 | ||
1246 | struct inode_operations ubifs_file_inode_operations = { | |
1247 | .setattr = ubifs_setattr, | |
1248 | .getattr = ubifs_getattr, | |
1249 | #ifdef CONFIG_UBIFS_FS_XATTR | |
1250 | .setxattr = ubifs_setxattr, | |
1251 | .getxattr = ubifs_getxattr, | |
1252 | .listxattr = ubifs_listxattr, | |
1253 | .removexattr = ubifs_removexattr, | |
1254 | #endif | |
1255 | }; | |
1256 | ||
1257 | struct inode_operations ubifs_symlink_inode_operations = { | |
1258 | .readlink = generic_readlink, | |
1259 | .follow_link = ubifs_follow_link, | |
1260 | .setattr = ubifs_setattr, | |
1261 | .getattr = ubifs_getattr, | |
1262 | }; | |
1263 | ||
1264 | struct file_operations ubifs_file_operations = { | |
1265 | .llseek = generic_file_llseek, | |
1266 | .read = do_sync_read, | |
1267 | .write = do_sync_write, | |
1268 | .aio_read = generic_file_aio_read, | |
1269 | .aio_write = ubifs_aio_write, | |
1270 | .mmap = ubifs_file_mmap, | |
1271 | .fsync = ubifs_fsync, | |
1272 | .unlocked_ioctl = ubifs_ioctl, | |
1273 | .splice_read = generic_file_splice_read, | |
1274 | #ifdef CONFIG_COMPAT | |
1275 | .compat_ioctl = ubifs_compat_ioctl, | |
1276 | #endif | |
1277 | }; |