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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 for 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
28 * the page is dirty and is used for optimization purposes - dirty pages are
29 * not budgeted so the flag shows that 'ubifs_write_end()' should not release
30 * the budget for this page. The @PG_checked flag is set if full budgeting is
31 * required for the page e.g., when it corresponds to a file hole or it is
32 * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because
33 * it is OK to fail in this function, and the budget is released in
34 * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry
35 * information about how the page was budgeted, to make it possible to release
36 * the budget properly.
37 *
38 * A thing to keep in mind: inode @i_mutex is locked in most VFS operations we
39 * implement. However, this is not true for 'ubifs_writepage()', which may be
40 * called with @i_mutex unlocked. For example, when pdflush is doing background
41 * write-back, it calls 'ubifs_writepage()' with unlocked @i_mutex. At "normal"
42 * work-paths the @i_mutex is locked in 'ubifs_writepage()', e.g. in the
43 * "sys_write -> alloc_pages -> direct reclaim path". So, in 'ubifs_writepage()'
44 * we are only guaranteed that the page is locked.
45 *
46 * Similarly, @i_mutex is not always locked in 'ubifs_readpage()', e.g., the
47 * read-ahead path does not lock it ("sys_read -> generic_file_aio_read ->
48 * ondemand_readahead -> readpage"). In case of readahead, @I_SYNC flag is not
49 * set as well. However, UBIFS disables readahead.
50 */
51
52#include "ubifs.h"
53#include <linux/mount.h>
54#include <linux/namei.h>
55#include <linux/slab.h>
56
57static 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(le64_to_cpu(dn->ch.sqnum) >
75 ubifs_inode(inode)->creat_sqnum);
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
97dump:
98 ubifs_err("bad data node (block %u, inode %lu)",
99 block, inode->i_ino);
100 ubifs_dump_node(c, dn);
101 return -EINVAL;
102}
103
104static 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 } else if (block + 1 == beyond) {
150 int dlen = le32_to_cpu(dn->size);
151 int ilen = i_size & (UBIFS_BLOCK_SIZE - 1);
152
153 if (ilen && ilen < dlen)
154 memset(addr + ilen, 0, dlen - ilen);
155 }
156 }
157 if (++i >= UBIFS_BLOCKS_PER_PAGE)
158 break;
159 block += 1;
160 addr += UBIFS_BLOCK_SIZE;
161 }
162 if (err) {
163 if (err == -ENOENT) {
164 /* Not found, so it must be a hole */
165 SetPageChecked(page);
166 dbg_gen("hole");
167 goto out_free;
168 }
169 ubifs_err("cannot read page %lu of inode %lu, error %d",
170 page->index, inode->i_ino, err);
171 goto error;
172 }
173
174out_free:
175 kfree(dn);
176out:
177 SetPageUptodate(page);
178 ClearPageError(page);
179 flush_dcache_page(page);
180 kunmap(page);
181 return 0;
182
183error:
184 kfree(dn);
185 ClearPageUptodate(page);
186 SetPageError(page);
187 flush_dcache_page(page);
188 kunmap(page);
189 return err;
190}
191
192/**
193 * release_new_page_budget - release budget of a new page.
194 * @c: UBIFS file-system description object
195 *
196 * This is a helper function which releases budget corresponding to the budget
197 * of one new page of data.
198 */
199static void release_new_page_budget(struct ubifs_info *c)
200{
201 struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 };
202
203 ubifs_release_budget(c, &req);
204}
205
206/**
207 * release_existing_page_budget - release budget of an existing page.
208 * @c: UBIFS file-system description object
209 *
210 * This is a helper function which releases budget corresponding to the budget
211 * of changing one one page of data which already exists on the flash media.
212 */
213static void release_existing_page_budget(struct ubifs_info *c)
214{
215 struct ubifs_budget_req req = { .dd_growth = c->bi.page_budget};
216
217 ubifs_release_budget(c, &req);
218}
219
220static int write_begin_slow(struct address_space *mapping,
221 loff_t pos, unsigned len, struct page **pagep,
222 unsigned flags)
223{
224 struct inode *inode = mapping->host;
225 struct ubifs_info *c = inode->i_sb->s_fs_info;
226 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
227 struct ubifs_budget_req req = { .new_page = 1 };
228 int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
229 struct page *page;
230
231 dbg_gen("ino %lu, pos %llu, len %u, i_size %lld",
232 inode->i_ino, pos, len, inode->i_size);
233
234 /*
235 * At the slow path we have to budget before locking the page, because
236 * budgeting may force write-back, which would wait on locked pages and
237 * deadlock if we had the page locked. At this point we do not know
238 * anything about the page, so assume that this is a new page which is
239 * written to a hole. This corresponds to largest budget. Later the
240 * budget will be amended if this is not true.
241 */
242 if (appending)
243 /* We are appending data, budget for inode change */
244 req.dirtied_ino = 1;
245
246 err = ubifs_budget_space(c, &req);
247 if (unlikely(err))
248 return err;
249
250 page = grab_cache_page_write_begin(mapping, index, flags);
251 if (unlikely(!page)) {
252 ubifs_release_budget(c, &req);
253 return -ENOMEM;
254 }
255
256 if (!PageUptodate(page)) {
257 if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
258 SetPageChecked(page);
259 else {
260 err = do_readpage(page);
261 if (err) {
262 unlock_page(page);
263 page_cache_release(page);
264 return err;
265 }
266 }
267
268 SetPageUptodate(page);
269 ClearPageError(page);
270 }
271
272 if (PagePrivate(page))
273 /*
274 * The page is dirty, which means it was budgeted twice:
275 * o first time the budget was allocated by the task which
276 * made the page dirty and set the PG_private flag;
277 * o and then we budgeted for it for the second time at the
278 * very beginning of this function.
279 *
280 * So what we have to do is to release the page budget we
281 * allocated.
282 */
283 release_new_page_budget(c);
284 else if (!PageChecked(page))
285 /*
286 * We are changing a page which already exists on the media.
287 * This means that changing the page does not make the amount
288 * of indexing information larger, and this part of the budget
289 * which we have already acquired may be released.
290 */
291 ubifs_convert_page_budget(c);
292
293 if (appending) {
294 struct ubifs_inode *ui = ubifs_inode(inode);
295
296 /*
297 * 'ubifs_write_end()' is optimized from the fast-path part of
298 * 'ubifs_write_begin()' and expects the @ui_mutex to be locked
299 * if data is appended.
300 */
301 mutex_lock(&ui->ui_mutex);
302 if (ui->dirty)
303 /*
304 * The inode is dirty already, so we may free the
305 * budget we allocated.
306 */
307 ubifs_release_dirty_inode_budget(c, ui);
308 }
309
310 *pagep = page;
311 return 0;
312}
313
314/**
315 * allocate_budget - allocate budget for 'ubifs_write_begin()'.
316 * @c: UBIFS file-system description object
317 * @page: page to allocate budget for
318 * @ui: UBIFS inode object the page belongs to
319 * @appending: non-zero if the page is appended
320 *
321 * This is a helper function for 'ubifs_write_begin()' which allocates budget
322 * for the operation. The budget is allocated differently depending on whether
323 * this is appending, whether the page is dirty or not, and so on. This
324 * function leaves the @ui->ui_mutex locked in case of appending. Returns zero
325 * in case of success and %-ENOSPC in case of failure.
326 */
327static int allocate_budget(struct ubifs_info *c, struct page *page,
328 struct ubifs_inode *ui, int appending)
329{
330 struct ubifs_budget_req req = { .fast = 1 };
331
332 if (PagePrivate(page)) {
333 if (!appending)
334 /*
335 * The page is dirty and we are not appending, which
336 * means no budget is needed at all.
337 */
338 return 0;
339
340 mutex_lock(&ui->ui_mutex);
341 if (ui->dirty)
342 /*
343 * The page is dirty and we are appending, so the inode
344 * has to be marked as dirty. However, it is already
345 * dirty, so we do not need any budget. We may return,
346 * but @ui->ui_mutex hast to be left locked because we
347 * should prevent write-back from flushing the inode
348 * and freeing the budget. The lock will be released in
349 * 'ubifs_write_end()'.
350 */
351 return 0;
352
353 /*
354 * The page is dirty, we are appending, the inode is clean, so
355 * we need to budget the inode change.
356 */
357 req.dirtied_ino = 1;
358 } else {
359 if (PageChecked(page))
360 /*
361 * The page corresponds to a hole and does not
362 * exist on the media. So changing it makes
363 * make the amount of indexing information
364 * larger, and we have to budget for a new
365 * page.
366 */
367 req.new_page = 1;
368 else
369 /*
370 * Not a hole, the change will not add any new
371 * indexing information, budget for page
372 * change.
373 */
374 req.dirtied_page = 1;
375
376 if (appending) {
377 mutex_lock(&ui->ui_mutex);
378 if (!ui->dirty)
379 /*
380 * The inode is clean but we will have to mark
381 * it as dirty because we are appending. This
382 * needs a budget.
383 */
384 req.dirtied_ino = 1;
385 }
386 }
387
388 return ubifs_budget_space(c, &req);
389}
390
391/*
392 * This function is called when a page of data is going to be written. Since
393 * the page of data will not necessarily go to the flash straight away, UBIFS
394 * has to reserve space on the media for it, which is done by means of
395 * budgeting.
396 *
397 * This is the hot-path of the file-system and we are trying to optimize it as
398 * much as possible. For this reasons it is split on 2 parts - slow and fast.
399 *
400 * There many budgeting cases:
401 * o a new page is appended - we have to budget for a new page and for
402 * changing the inode; however, if the inode is already dirty, there is
403 * no need to budget for it;
404 * o an existing clean page is changed - we have budget for it; if the page
405 * does not exist on the media (a hole), we have to budget for a new
406 * page; otherwise, we may budget for changing an existing page; the
407 * difference between these cases is that changing an existing page does
408 * not introduce anything new to the FS indexing information, so it does
409 * not grow, and smaller budget is acquired in this case;
410 * o an existing dirty page is changed - no need to budget at all, because
411 * the page budget has been acquired by earlier, when the page has been
412 * marked dirty.
413 *
414 * UBIFS budgeting sub-system may force write-back if it thinks there is no
415 * space to reserve. This imposes some locking restrictions and makes it
416 * impossible to take into account the above cases, and makes it impossible to
417 * optimize budgeting.
418 *
419 * The solution for this is that the fast path of 'ubifs_write_begin()' assumes
420 * there is a plenty of flash space and the budget will be acquired quickly,
421 * without forcing write-back. The slow path does not make this assumption.
422 */
423static int ubifs_write_begin(struct file *file, struct address_space *mapping,
424 loff_t pos, unsigned len, unsigned flags,
425 struct page **pagep, void **fsdata)
426{
427 struct inode *inode = mapping->host;
428 struct ubifs_info *c = inode->i_sb->s_fs_info;
429 struct ubifs_inode *ui = ubifs_inode(inode);
430 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
431 int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
432 int skipped_read = 0;
433 struct page *page;
434
435 ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size);
436 ubifs_assert(!c->ro_media && !c->ro_mount);
437
438 if (unlikely(c->ro_error))
439 return -EROFS;
440
441 /* Try out the fast-path part first */
442 page = grab_cache_page_write_begin(mapping, index, flags);
443 if (unlikely(!page))
444 return -ENOMEM;
445
446 if (!PageUptodate(page)) {
447 /* The page is not loaded from the flash */
448 if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) {
449 /*
450 * We change whole page so no need to load it. But we
451 * do not know whether this page exists on the media or
452 * not, so we assume the latter because it requires
453 * larger budget. The assumption is that it is better
454 * to budget a bit more than to read the page from the
455 * media. Thus, we are setting the @PG_checked flag
456 * here.
457 */
458 SetPageChecked(page);
459 skipped_read = 1;
460 } else {
461 err = do_readpage(page);
462 if (err) {
463 unlock_page(page);
464 page_cache_release(page);
465 return err;
466 }
467 }
468
469 SetPageUptodate(page);
470 ClearPageError(page);
471 }
472
473 err = allocate_budget(c, page, ui, appending);
474 if (unlikely(err)) {
475 ubifs_assert(err == -ENOSPC);
476 /*
477 * If we skipped reading the page because we were going to
478 * write all of it, then it is not up to date.
479 */
480 if (skipped_read) {
481 ClearPageChecked(page);
482 ClearPageUptodate(page);
483 }
484 /*
485 * Budgeting failed which means it would have to force
486 * write-back but didn't, because we set the @fast flag in the
487 * request. Write-back cannot be done now, while we have the
488 * page locked, because it would deadlock. Unlock and free
489 * everything and fall-back to slow-path.
490 */
491 if (appending) {
492 ubifs_assert(mutex_is_locked(&ui->ui_mutex));
493 mutex_unlock(&ui->ui_mutex);
494 }
495 unlock_page(page);
496 page_cache_release(page);
497
498 return write_begin_slow(mapping, pos, len, pagep, flags);
499 }
500
501 /*
502 * Whee, we acquired budgeting quickly - without involving
503 * garbage-collection, committing or forcing write-back. We return
504 * with @ui->ui_mutex locked if we are appending pages, and unlocked
505 * otherwise. This is an optimization (slightly hacky though).
506 */
507 *pagep = page;
508 return 0;
509
510}
511
512/**
513 * cancel_budget - cancel budget.
514 * @c: UBIFS file-system description object
515 * @page: page to cancel budget for
516 * @ui: UBIFS inode object the page belongs to
517 * @appending: non-zero if the page is appended
518 *
519 * This is a helper function for a page write operation. It unlocks the
520 * @ui->ui_mutex in case of appending.
521 */
522static void cancel_budget(struct ubifs_info *c, struct page *page,
523 struct ubifs_inode *ui, int appending)
524{
525 if (appending) {
526 if (!ui->dirty)
527 ubifs_release_dirty_inode_budget(c, ui);
528 mutex_unlock(&ui->ui_mutex);
529 }
530 if (!PagePrivate(page)) {
531 if (PageChecked(page))
532 release_new_page_budget(c);
533 else
534 release_existing_page_budget(c);
535 }
536}
537
538static int ubifs_write_end(struct file *file, struct address_space *mapping,
539 loff_t pos, unsigned len, unsigned copied,
540 struct page *page, void *fsdata)
541{
542 struct inode *inode = mapping->host;
543 struct ubifs_inode *ui = ubifs_inode(inode);
544 struct ubifs_info *c = inode->i_sb->s_fs_info;
545 loff_t end_pos = pos + len;
546 int appending = !!(end_pos > inode->i_size);
547
548 dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld",
549 inode->i_ino, pos, page->index, len, copied, inode->i_size);
550
551 if (unlikely(copied < len && len == PAGE_CACHE_SIZE)) {
552 /*
553 * VFS copied less data to the page that it intended and
554 * declared in its '->write_begin()' call via the @len
555 * argument. If the page was not up-to-date, and @len was
556 * @PAGE_CACHE_SIZE, the 'ubifs_write_begin()' function did
557 * not load it from the media (for optimization reasons). This
558 * means that part of the page contains garbage. So read the
559 * page now.
560 */
561 dbg_gen("copied %d instead of %d, read page and repeat",
562 copied, len);
563 cancel_budget(c, page, ui, appending);
564 ClearPageChecked(page);
565
566 /*
567 * Return 0 to force VFS to repeat the whole operation, or the
568 * error code if 'do_readpage()' fails.
569 */
570 copied = do_readpage(page);
571 goto out;
572 }
573
574 if (!PagePrivate(page)) {
575 SetPagePrivate(page);
576 atomic_long_inc(&c->dirty_pg_cnt);
577 __set_page_dirty_nobuffers(page);
578 }
579
580 if (appending) {
581 i_size_write(inode, end_pos);
582 ui->ui_size = end_pos;
583 /*
584 * Note, we do not set @I_DIRTY_PAGES (which means that the
585 * inode has dirty pages), this has been done in
586 * '__set_page_dirty_nobuffers()'.
587 */
588 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
589 ubifs_assert(mutex_is_locked(&ui->ui_mutex));
590 mutex_unlock(&ui->ui_mutex);
591 }
592
593out:
594 unlock_page(page);
595 page_cache_release(page);
596 return copied;
597}
598
599/**
600 * populate_page - copy data nodes into a page for bulk-read.
601 * @c: UBIFS file-system description object
602 * @page: page
603 * @bu: bulk-read information
604 * @n: next zbranch slot
605 *
606 * This function returns %0 on success and a negative error code on failure.
607 */
608static int populate_page(struct ubifs_info *c, struct page *page,
609 struct bu_info *bu, int *n)
610{
611 int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 0, read = 0;
612 struct inode *inode = page->mapping->host;
613 loff_t i_size = i_size_read(inode);
614 unsigned int page_block;
615 void *addr, *zaddr;
616 pgoff_t end_index;
617
618 dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
619 inode->i_ino, page->index, i_size, page->flags);
620
621 addr = zaddr = kmap(page);
622
623 end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
624 if (!i_size || page->index > end_index) {
625 hole = 1;
626 memset(addr, 0, PAGE_CACHE_SIZE);
627 goto out_hole;
628 }
629
630 page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
631 while (1) {
632 int err, len, out_len, dlen;
633
634 if (nn >= bu->cnt) {
635 hole = 1;
636 memset(addr, 0, UBIFS_BLOCK_SIZE);
637 } else if (key_block(c, &bu->zbranch[nn].key) == page_block) {
638 struct ubifs_data_node *dn;
639
640 dn = bu->buf + (bu->zbranch[nn].offs - offs);
641
642 ubifs_assert(le64_to_cpu(dn->ch.sqnum) >
643 ubifs_inode(inode)->creat_sqnum);
644
645 len = le32_to_cpu(dn->size);
646 if (len <= 0 || len > UBIFS_BLOCK_SIZE)
647 goto out_err;
648
649 dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
650 out_len = UBIFS_BLOCK_SIZE;
651 err = ubifs_decompress(&dn->data, dlen, addr, &out_len,
652 le16_to_cpu(dn->compr_type));
653 if (err || len != out_len)
654 goto out_err;
655
656 if (len < UBIFS_BLOCK_SIZE)
657 memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
658
659 nn += 1;
660 read = (i << UBIFS_BLOCK_SHIFT) + len;
661 } else if (key_block(c, &bu->zbranch[nn].key) < page_block) {
662 nn += 1;
663 continue;
664 } else {
665 hole = 1;
666 memset(addr, 0, UBIFS_BLOCK_SIZE);
667 }
668 if (++i >= UBIFS_BLOCKS_PER_PAGE)
669 break;
670 addr += UBIFS_BLOCK_SIZE;
671 page_block += 1;
672 }
673
674 if (end_index == page->index) {
675 int len = i_size & (PAGE_CACHE_SIZE - 1);
676
677 if (len && len < read)
678 memset(zaddr + len, 0, read - len);
679 }
680
681out_hole:
682 if (hole) {
683 SetPageChecked(page);
684 dbg_gen("hole");
685 }
686
687 SetPageUptodate(page);
688 ClearPageError(page);
689 flush_dcache_page(page);
690 kunmap(page);
691 *n = nn;
692 return 0;
693
694out_err:
695 ClearPageUptodate(page);
696 SetPageError(page);
697 flush_dcache_page(page);
698 kunmap(page);
699 ubifs_err("bad data node (block %u, inode %lu)",
700 page_block, inode->i_ino);
701 return -EINVAL;
702}
703
704/**
705 * ubifs_do_bulk_read - do bulk-read.
706 * @c: UBIFS file-system description object
707 * @bu: bulk-read information
708 * @page1: first page to read
709 *
710 * This function returns %1 if the bulk-read is done, otherwise %0 is returned.
711 */
712static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu,
713 struct page *page1)
714{
715 pgoff_t offset = page1->index, end_index;
716 struct address_space *mapping = page1->mapping;
717 struct inode *inode = mapping->host;
718 struct ubifs_inode *ui = ubifs_inode(inode);
719 int err, page_idx, page_cnt, ret = 0, n = 0;
720 int allocate = bu->buf ? 0 : 1;
721 loff_t isize;
722
723 err = ubifs_tnc_get_bu_keys(c, bu);
724 if (err)
725 goto out_warn;
726
727 if (bu->eof) {
728 /* Turn off bulk-read at the end of the file */
729 ui->read_in_a_row = 1;
730 ui->bulk_read = 0;
731 }
732
733 page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT;
734 if (!page_cnt) {
735 /*
736 * This happens when there are multiple blocks per page and the
737 * blocks for the first page we are looking for, are not
738 * together. If all the pages were like this, bulk-read would
739 * reduce performance, so we turn it off for a while.
740 */
741 goto out_bu_off;
742 }
743
744 if (bu->cnt) {
745 if (allocate) {
746 /*
747 * Allocate bulk-read buffer depending on how many data
748 * nodes we are going to read.
749 */
750 bu->buf_len = bu->zbranch[bu->cnt - 1].offs +
751 bu->zbranch[bu->cnt - 1].len -
752 bu->zbranch[0].offs;
753 ubifs_assert(bu->buf_len > 0);
754 ubifs_assert(bu->buf_len <= c->leb_size);
755 bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
756 if (!bu->buf)
757 goto out_bu_off;
758 }
759
760 err = ubifs_tnc_bulk_read(c, bu);
761 if (err)
762 goto out_warn;
763 }
764
765 err = populate_page(c, page1, bu, &n);
766 if (err)
767 goto out_warn;
768
769 unlock_page(page1);
770 ret = 1;
771
772 isize = i_size_read(inode);
773 if (isize == 0)
774 goto out_free;
775 end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
776
777 for (page_idx = 1; page_idx < page_cnt; page_idx++) {
778 pgoff_t page_offset = offset + page_idx;
779 struct page *page;
780
781 if (page_offset > end_index)
782 break;
783 page = find_or_create_page(mapping, page_offset,
784 GFP_NOFS | __GFP_COLD);
785 if (!page)
786 break;
787 if (!PageUptodate(page))
788 err = populate_page(c, page, bu, &n);
789 unlock_page(page);
790 page_cache_release(page);
791 if (err)
792 break;
793 }
794
795 ui->last_page_read = offset + page_idx - 1;
796
797out_free:
798 if (allocate)
799 kfree(bu->buf);
800 return ret;
801
802out_warn:
803 ubifs_warn("ignoring error %d and skipping bulk-read", err);
804 goto out_free;
805
806out_bu_off:
807 ui->read_in_a_row = ui->bulk_read = 0;
808 goto out_free;
809}
810
811/**
812 * ubifs_bulk_read - determine whether to bulk-read and, if so, do it.
813 * @page: page from which to start bulk-read.
814 *
815 * Some flash media are capable of reading sequentially at faster rates. UBIFS
816 * bulk-read facility is designed to take advantage of that, by reading in one
817 * go consecutive data nodes that are also located consecutively in the same
818 * LEB. This function returns %1 if a bulk-read is done and %0 otherwise.
819 */
820static int ubifs_bulk_read(struct page *page)
821{
822 struct inode *inode = page->mapping->host;
823 struct ubifs_info *c = inode->i_sb->s_fs_info;
824 struct ubifs_inode *ui = ubifs_inode(inode);
825 pgoff_t index = page->index, last_page_read = ui->last_page_read;
826 struct bu_info *bu;
827 int err = 0, allocated = 0;
828
829 ui->last_page_read = index;
830 if (!c->bulk_read)
831 return 0;
832
833 /*
834 * Bulk-read is protected by @ui->ui_mutex, but it is an optimization,
835 * so don't bother if we cannot lock the mutex.
836 */
837 if (!mutex_trylock(&ui->ui_mutex))
838 return 0;
839
840 if (index != last_page_read + 1) {
841 /* Turn off bulk-read if we stop reading sequentially */
842 ui->read_in_a_row = 1;
843 if (ui->bulk_read)
844 ui->bulk_read = 0;
845 goto out_unlock;
846 }
847
848 if (!ui->bulk_read) {
849 ui->read_in_a_row += 1;
850 if (ui->read_in_a_row < 3)
851 goto out_unlock;
852 /* Three reads in a row, so switch on bulk-read */
853 ui->bulk_read = 1;
854 }
855
856 /*
857 * If possible, try to use pre-allocated bulk-read information, which
858 * is protected by @c->bu_mutex.
859 */
860 if (mutex_trylock(&c->bu_mutex))
861 bu = &c->bu;
862 else {
863 bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
864 if (!bu)
865 goto out_unlock;
866
867 bu->buf = NULL;
868 allocated = 1;
869 }
870
871 bu->buf_len = c->max_bu_buf_len;
872 data_key_init(c, &bu->key, inode->i_ino,
873 page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
874 err = ubifs_do_bulk_read(c, bu, page);
875
876 if (!allocated)
877 mutex_unlock(&c->bu_mutex);
878 else
879 kfree(bu);
880
881out_unlock:
882 mutex_unlock(&ui->ui_mutex);
883 return err;
884}
885
886static int ubifs_readpage(struct file *file, struct page *page)
887{
888 if (ubifs_bulk_read(page))
889 return 0;
890 do_readpage(page);
891 unlock_page(page);
892 return 0;
893}
894
895static int do_writepage(struct page *page, int len)
896{
897 int err = 0, i, blen;
898 unsigned int block;
899 void *addr;
900 union ubifs_key key;
901 struct inode *inode = page->mapping->host;
902 struct ubifs_info *c = inode->i_sb->s_fs_info;
903
904#ifdef UBIFS_DEBUG
905 spin_lock(&ui->ui_lock);
906 ubifs_assert(page->index <= ui->synced_i_size << PAGE_CACHE_SIZE);
907 spin_unlock(&ui->ui_lock);
908#endif
909
910 /* Update radix tree tags */
911 set_page_writeback(page);
912
913 addr = kmap(page);
914 block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
915 i = 0;
916 while (len) {
917 blen = min_t(int, len, UBIFS_BLOCK_SIZE);
918 data_key_init(c, &key, inode->i_ino, block);
919 err = ubifs_jnl_write_data(c, inode, &key, addr, blen);
920 if (err)
921 break;
922 if (++i >= UBIFS_BLOCKS_PER_PAGE)
923 break;
924 block += 1;
925 addr += blen;
926 len -= blen;
927 }
928 if (err) {
929 SetPageError(page);
930 ubifs_err("cannot write page %lu of inode %lu, error %d",
931 page->index, inode->i_ino, err);
932 ubifs_ro_mode(c, err);
933 }
934
935 ubifs_assert(PagePrivate(page));
936 if (PageChecked(page))
937 release_new_page_budget(c);
938 else
939 release_existing_page_budget(c);
940
941 atomic_long_dec(&c->dirty_pg_cnt);
942 ClearPagePrivate(page);
943 ClearPageChecked(page);
944
945 kunmap(page);
946 unlock_page(page);
947 end_page_writeback(page);
948 return err;
949}
950
951/*
952 * When writing-back dirty inodes, VFS first writes-back pages belonging to the
953 * inode, then the inode itself. For UBIFS this may cause a problem. Consider a
954 * situation when a we have an inode with size 0, then a megabyte of data is
955 * appended to the inode, then write-back starts and flushes some amount of the
956 * dirty pages, the journal becomes full, commit happens and finishes, and then
957 * an unclean reboot happens. When the file system is mounted next time, the
958 * inode size would still be 0, but there would be many pages which are beyond
959 * the inode size, they would be indexed and consume flash space. Because the
960 * journal has been committed, the replay would not be able to detect this
961 * situation and correct the inode size. This means UBIFS would have to scan
962 * whole index and correct all inode sizes, which is long an unacceptable.
963 *
964 * To prevent situations like this, UBIFS writes pages back only if they are
965 * within the last synchronized inode size, i.e. the size which has been
966 * written to the flash media last time. Otherwise, UBIFS forces inode
967 * write-back, thus making sure the on-flash inode contains current inode size,
968 * and then keeps writing pages back.
969 *
970 * Some locking issues explanation. 'ubifs_writepage()' first is called with
971 * the page locked, and it locks @ui_mutex. However, write-back does take inode
972 * @i_mutex, which means other VFS operations may be run on this inode at the
973 * same time. And the problematic one is truncation to smaller size, from where
974 * we have to call 'truncate_setsize()', which first changes @inode->i_size,
975 * then drops the truncated pages. And while dropping the pages, it takes the
976 * page lock. This means that 'do_truncation()' cannot call 'truncate_setsize()'
977 * with @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'.
978 * This means that @inode->i_size is changed while @ui_mutex is unlocked.
979 *
980 * XXX(truncate): with the new truncate sequence this is not true anymore,
981 * and the calls to truncate_setsize can be move around freely. They should
982 * be moved to the very end of the truncate sequence.
983 *
984 * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond
985 * inode size. How do we do this if @inode->i_size may became smaller while we
986 * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the
987 * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size
988 * internally and updates it under @ui_mutex.
989 *
990 * Q: why we do not worry that if we race with truncation, we may end up with a
991 * situation when the inode is truncated while we are in the middle of
992 * 'do_writepage()', so we do write beyond inode size?
993 * A: If we are in the middle of 'do_writepage()', truncation would be locked
994 * on the page lock and it would not write the truncated inode node to the
995 * journal before we have finished.
996 */
997static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
998{
999 struct inode *inode = page->mapping->host;
1000 struct ubifs_inode *ui = ubifs_inode(inode);
1001 loff_t i_size = i_size_read(inode), synced_i_size;
1002 pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
1003 int err, len = i_size & (PAGE_CACHE_SIZE - 1);
1004 void *kaddr;
1005
1006 dbg_gen("ino %lu, pg %lu, pg flags %#lx",
1007 inode->i_ino, page->index, page->flags);
1008 ubifs_assert(PagePrivate(page));
1009
1010 /* Is the page fully outside @i_size? (truncate in progress) */
1011 if (page->index > end_index || (page->index == end_index && !len)) {
1012 err = 0;
1013 goto out_unlock;
1014 }
1015
1016 spin_lock(&ui->ui_lock);
1017 synced_i_size = ui->synced_i_size;
1018 spin_unlock(&ui->ui_lock);
1019
1020 /* Is the page fully inside @i_size? */
1021 if (page->index < end_index) {
1022 if (page->index >= synced_i_size >> PAGE_CACHE_SHIFT) {
1023 err = inode->i_sb->s_op->write_inode(inode, NULL);
1024 if (err)
1025 goto out_unlock;
1026 /*
1027 * The inode has been written, but the write-buffer has
1028 * not been synchronized, so in case of an unclean
1029 * reboot we may end up with some pages beyond inode
1030 * size, but they would be in the journal (because
1031 * commit flushes write buffers) and recovery would deal
1032 * with this.
1033 */
1034 }
1035 return do_writepage(page, PAGE_CACHE_SIZE);
1036 }
1037
1038 /*
1039 * The page straddles @i_size. It must be zeroed out on each and every
1040 * writepage invocation because it may be mmapped. "A file is mapped
1041 * in multiples of the page size. For a file that is not a multiple of
1042 * the page size, the remaining memory is zeroed when mapped, and
1043 * writes to that region are not written out to the file."
1044 */
1045 kaddr = kmap_atomic(page);
1046 memset(kaddr + len, 0, PAGE_CACHE_SIZE - len);
1047 flush_dcache_page(page);
1048 kunmap_atomic(kaddr);
1049
1050 if (i_size > synced_i_size) {
1051 err = inode->i_sb->s_op->write_inode(inode, NULL);
1052 if (err)
1053 goto out_unlock;
1054 }
1055
1056 return do_writepage(page, len);
1057
1058out_unlock:
1059 unlock_page(page);
1060 return err;
1061}
1062
1063/**
1064 * do_attr_changes - change inode attributes.
1065 * @inode: inode to change attributes for
1066 * @attr: describes attributes to change
1067 */
1068static void do_attr_changes(struct inode *inode, const struct iattr *attr)
1069{
1070 if (attr->ia_valid & ATTR_UID)
1071 inode->i_uid = attr->ia_uid;
1072 if (attr->ia_valid & ATTR_GID)
1073 inode->i_gid = attr->ia_gid;
1074 if (attr->ia_valid & ATTR_ATIME)
1075 inode->i_atime = timespec_trunc(attr->ia_atime,
1076 inode->i_sb->s_time_gran);
1077 if (attr->ia_valid & ATTR_MTIME)
1078 inode->i_mtime = timespec_trunc(attr->ia_mtime,
1079 inode->i_sb->s_time_gran);
1080 if (attr->ia_valid & ATTR_CTIME)
1081 inode->i_ctime = timespec_trunc(attr->ia_ctime,
1082 inode->i_sb->s_time_gran);
1083 if (attr->ia_valid & ATTR_MODE) {
1084 umode_t mode = attr->ia_mode;
1085
1086 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
1087 mode &= ~S_ISGID;
1088 inode->i_mode = mode;
1089 }
1090}
1091
1092/**
1093 * do_truncation - truncate an inode.
1094 * @c: UBIFS file-system description object
1095 * @inode: inode to truncate
1096 * @attr: inode attribute changes description
1097 *
1098 * This function implements VFS '->setattr()' call when the inode is truncated
1099 * to a smaller size. Returns zero in case of success and a negative error code
1100 * in case of failure.
1101 */
1102static int do_truncation(struct ubifs_info *c, struct inode *inode,
1103 const struct iattr *attr)
1104{
1105 int err;
1106 struct ubifs_budget_req req;
1107 loff_t old_size = inode->i_size, new_size = attr->ia_size;
1108 int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1;
1109 struct ubifs_inode *ui = ubifs_inode(inode);
1110
1111 dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size);
1112 memset(&req, 0, sizeof(struct ubifs_budget_req));
1113
1114 /*
1115 * If this is truncation to a smaller size, and we do not truncate on a
1116 * block boundary, budget for changing one data block, because the last
1117 * block will be re-written.
1118 */
1119 if (new_size & (UBIFS_BLOCK_SIZE - 1))
1120 req.dirtied_page = 1;
1121
1122 req.dirtied_ino = 1;
1123 /* A funny way to budget for truncation node */
1124 req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ;
1125 err = ubifs_budget_space(c, &req);
1126 if (err) {
1127 /*
1128 * Treat truncations to zero as deletion and always allow them,
1129 * just like we do for '->unlink()'.
1130 */
1131 if (new_size || err != -ENOSPC)
1132 return err;
1133 budgeted = 0;
1134 }
1135
1136 truncate_setsize(inode, new_size);
1137
1138 if (offset) {
1139 pgoff_t index = new_size >> PAGE_CACHE_SHIFT;
1140 struct page *page;
1141
1142 page = find_lock_page(inode->i_mapping, index);
1143 if (page) {
1144 if (PageDirty(page)) {
1145 /*
1146 * 'ubifs_jnl_truncate()' will try to truncate
1147 * the last data node, but it contains
1148 * out-of-date data because the page is dirty.
1149 * Write the page now, so that
1150 * 'ubifs_jnl_truncate()' will see an already
1151 * truncated (and up to date) data node.
1152 */
1153 ubifs_assert(PagePrivate(page));
1154
1155 clear_page_dirty_for_io(page);
1156 if (UBIFS_BLOCKS_PER_PAGE_SHIFT)
1157 offset = new_size &
1158 (PAGE_CACHE_SIZE - 1);
1159 err = do_writepage(page, offset);
1160 page_cache_release(page);
1161 if (err)
1162 goto out_budg;
1163 /*
1164 * We could now tell 'ubifs_jnl_truncate()' not
1165 * to read the last block.
1166 */
1167 } else {
1168 /*
1169 * We could 'kmap()' the page and pass the data
1170 * to 'ubifs_jnl_truncate()' to save it from
1171 * having to read it.
1172 */
1173 unlock_page(page);
1174 page_cache_release(page);
1175 }
1176 }
1177 }
1178
1179 mutex_lock(&ui->ui_mutex);
1180 ui->ui_size = inode->i_size;
1181 /* Truncation changes inode [mc]time */
1182 inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1183 /* Other attributes may be changed at the same time as well */
1184 do_attr_changes(inode, attr);
1185 err = ubifs_jnl_truncate(c, inode, old_size, new_size);
1186 mutex_unlock(&ui->ui_mutex);
1187
1188out_budg:
1189 if (budgeted)
1190 ubifs_release_budget(c, &req);
1191 else {
1192 c->bi.nospace = c->bi.nospace_rp = 0;
1193 smp_wmb();
1194 }
1195 return err;
1196}
1197
1198/**
1199 * do_setattr - change inode attributes.
1200 * @c: UBIFS file-system description object
1201 * @inode: inode to change attributes for
1202 * @attr: inode attribute changes description
1203 *
1204 * This function implements VFS '->setattr()' call for all cases except
1205 * truncations to smaller size. Returns zero in case of success and a negative
1206 * error code in case of failure.
1207 */
1208static int do_setattr(struct ubifs_info *c, struct inode *inode,
1209 const struct iattr *attr)
1210{
1211 int err, release;
1212 loff_t new_size = attr->ia_size;
1213 struct ubifs_inode *ui = ubifs_inode(inode);
1214 struct ubifs_budget_req req = { .dirtied_ino = 1,
1215 .dirtied_ino_d = ALIGN(ui->data_len, 8) };
1216
1217 err = ubifs_budget_space(c, &req);
1218 if (err)
1219 return err;
1220
1221 if (attr->ia_valid & ATTR_SIZE) {
1222 dbg_gen("size %lld -> %lld", inode->i_size, new_size);
1223 truncate_setsize(inode, new_size);
1224 }
1225
1226 mutex_lock(&ui->ui_mutex);
1227 if (attr->ia_valid & ATTR_SIZE) {
1228 /* Truncation changes inode [mc]time */
1229 inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1230 /* 'truncate_setsize()' changed @i_size, update @ui_size */
1231 ui->ui_size = inode->i_size;
1232 }
1233
1234 do_attr_changes(inode, attr);
1235
1236 release = ui->dirty;
1237 if (attr->ia_valid & ATTR_SIZE)
1238 /*
1239 * Inode length changed, so we have to make sure
1240 * @I_DIRTY_DATASYNC is set.
1241 */
1242 __mark_inode_dirty(inode, I_DIRTY_SYNC | I_DIRTY_DATASYNC);
1243 else
1244 mark_inode_dirty_sync(inode);
1245 mutex_unlock(&ui->ui_mutex);
1246
1247 if (release)
1248 ubifs_release_budget(c, &req);
1249 if (IS_SYNC(inode))
1250 err = inode->i_sb->s_op->write_inode(inode, NULL);
1251 return err;
1252}
1253
1254int ubifs_setattr(struct dentry *dentry, struct iattr *attr)
1255{
1256 int err;
1257 struct inode *inode = dentry->d_inode;
1258 struct ubifs_info *c = inode->i_sb->s_fs_info;
1259
1260 dbg_gen("ino %lu, mode %#x, ia_valid %#x",
1261 inode->i_ino, inode->i_mode, attr->ia_valid);
1262 err = inode_change_ok(inode, attr);
1263 if (err)
1264 return err;
1265
1266 err = dbg_check_synced_i_size(c, inode);
1267 if (err)
1268 return err;
1269
1270 if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size)
1271 /* Truncation to a smaller size */
1272 err = do_truncation(c, inode, attr);
1273 else
1274 err = do_setattr(c, inode, attr);
1275
1276 return err;
1277}
1278
1279static void ubifs_invalidatepage(struct page *page, unsigned long offset)
1280{
1281 struct inode *inode = page->mapping->host;
1282 struct ubifs_info *c = inode->i_sb->s_fs_info;
1283
1284 ubifs_assert(PagePrivate(page));
1285 if (offset)
1286 /* Partial page remains dirty */
1287 return;
1288
1289 if (PageChecked(page))
1290 release_new_page_budget(c);
1291 else
1292 release_existing_page_budget(c);
1293
1294 atomic_long_dec(&c->dirty_pg_cnt);
1295 ClearPagePrivate(page);
1296 ClearPageChecked(page);
1297}
1298
1299static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd)
1300{
1301 struct ubifs_inode *ui = ubifs_inode(dentry->d_inode);
1302
1303 nd_set_link(nd, ui->data);
1304 return NULL;
1305}
1306
1307int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1308{
1309 struct inode *inode = file->f_mapping->host;
1310 struct ubifs_info *c = inode->i_sb->s_fs_info;
1311 int err;
1312
1313 dbg_gen("syncing inode %lu", inode->i_ino);
1314
1315 if (c->ro_mount)
1316 /*
1317 * For some really strange reasons VFS does not filter out
1318 * 'fsync()' for R/O mounted file-systems as per 2.6.39.
1319 */
1320 return 0;
1321
1322 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
1323 if (err)
1324 return err;
1325 mutex_lock(&inode->i_mutex);
1326
1327 /* Synchronize the inode unless this is a 'datasync()' call. */
1328 if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) {
1329 err = inode->i_sb->s_op->write_inode(inode, NULL);
1330 if (err)
1331 goto out;
1332 }
1333
1334 /*
1335 * Nodes related to this inode may still sit in a write-buffer. Flush
1336 * them.
1337 */
1338 err = ubifs_sync_wbufs_by_inode(c, inode);
1339out:
1340 mutex_unlock(&inode->i_mutex);
1341 return err;
1342}
1343
1344/**
1345 * mctime_update_needed - check if mtime or ctime update is needed.
1346 * @inode: the inode to do the check for
1347 * @now: current time
1348 *
1349 * This helper function checks if the inode mtime/ctime should be updated or
1350 * not. If current values of the time-stamps are within the UBIFS inode time
1351 * granularity, they are not updated. This is an optimization.
1352 */
1353static inline int mctime_update_needed(const struct inode *inode,
1354 const struct timespec *now)
1355{
1356 if (!timespec_equal(&inode->i_mtime, now) ||
1357 !timespec_equal(&inode->i_ctime, now))
1358 return 1;
1359 return 0;
1360}
1361
1362/**
1363 * update_ctime - update mtime and ctime of an inode.
1364 * @c: UBIFS file-system description object
1365 * @inode: inode to update
1366 *
1367 * This function updates mtime and ctime of the inode if it is not equivalent to
1368 * current time. Returns zero in case of success and a negative error code in
1369 * case of failure.
1370 */
1371static int update_mctime(struct ubifs_info *c, struct inode *inode)
1372{
1373 struct timespec now = ubifs_current_time(inode);
1374 struct ubifs_inode *ui = ubifs_inode(inode);
1375
1376 if (mctime_update_needed(inode, &now)) {
1377 int err, release;
1378 struct ubifs_budget_req req = { .dirtied_ino = 1,
1379 .dirtied_ino_d = ALIGN(ui->data_len, 8) };
1380
1381 err = ubifs_budget_space(c, &req);
1382 if (err)
1383 return err;
1384
1385 mutex_lock(&ui->ui_mutex);
1386 inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1387 release = ui->dirty;
1388 mark_inode_dirty_sync(inode);
1389 mutex_unlock(&ui->ui_mutex);
1390 if (release)
1391 ubifs_release_budget(c, &req);
1392 }
1393
1394 return 0;
1395}
1396
1397static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov,
1398 unsigned long nr_segs, loff_t pos)
1399{
1400 int err;
1401 struct inode *inode = iocb->ki_filp->f_mapping->host;
1402 struct ubifs_info *c = inode->i_sb->s_fs_info;
1403
1404 err = update_mctime(c, inode);
1405 if (err)
1406 return err;
1407
1408 return generic_file_aio_write(iocb, iov, nr_segs, pos);
1409}
1410
1411static int ubifs_set_page_dirty(struct page *page)
1412{
1413 int ret;
1414
1415 ret = __set_page_dirty_nobuffers(page);
1416 /*
1417 * An attempt to dirty a page without budgeting for it - should not
1418 * happen.
1419 */
1420 ubifs_assert(ret == 0);
1421 return ret;
1422}
1423
1424static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
1425{
1426 /*
1427 * An attempt to release a dirty page without budgeting for it - should
1428 * not happen.
1429 */
1430 if (PageWriteback(page))
1431 return 0;
1432 ubifs_assert(PagePrivate(page));
1433 ubifs_assert(0);
1434 ClearPagePrivate(page);
1435 ClearPageChecked(page);
1436 return 1;
1437}
1438
1439/*
1440 * mmap()d file has taken write protection fault and is being made writable.
1441 * UBIFS must ensure page is budgeted for.
1442 */
1443static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma,
1444 struct vm_fault *vmf)
1445{
1446 struct page *page = vmf->page;
1447 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1448 struct ubifs_info *c = inode->i_sb->s_fs_info;
1449 struct timespec now = ubifs_current_time(inode);
1450 struct ubifs_budget_req req = { .new_page = 1 };
1451 int err, update_time;
1452
1453 dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index,
1454 i_size_read(inode));
1455 ubifs_assert(!c->ro_media && !c->ro_mount);
1456
1457 if (unlikely(c->ro_error))
1458 return VM_FAULT_SIGBUS; /* -EROFS */
1459
1460 /*
1461 * We have not locked @page so far so we may budget for changing the
1462 * page. Note, we cannot do this after we locked the page, because
1463 * budgeting may cause write-back which would cause deadlock.
1464 *
1465 * At the moment we do not know whether the page is dirty or not, so we
1466 * assume that it is not and budget for a new page. We could look at
1467 * the @PG_private flag and figure this out, but we may race with write
1468 * back and the page state may change by the time we lock it, so this
1469 * would need additional care. We do not bother with this at the
1470 * moment, although it might be good idea to do. Instead, we allocate
1471 * budget for a new page and amend it later on if the page was in fact
1472 * dirty.
1473 *
1474 * The budgeting-related logic of this function is similar to what we
1475 * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there
1476 * for more comments.
1477 */
1478 update_time = mctime_update_needed(inode, &now);
1479 if (update_time)
1480 /*
1481 * We have to change inode time stamp which requires extra
1482 * budgeting.
1483 */
1484 req.dirtied_ino = 1;
1485
1486 err = ubifs_budget_space(c, &req);
1487 if (unlikely(err)) {
1488 if (err == -ENOSPC)
1489 ubifs_warn("out of space for mmapped file "
1490 "(inode number %lu)", inode->i_ino);
1491 return VM_FAULT_SIGBUS;
1492 }
1493
1494 lock_page(page);
1495 if (unlikely(page->mapping != inode->i_mapping ||
1496 page_offset(page) > i_size_read(inode))) {
1497 /* Page got truncated out from underneath us */
1498 err = -EINVAL;
1499 goto out_unlock;
1500 }
1501
1502 if (PagePrivate(page))
1503 release_new_page_budget(c);
1504 else {
1505 if (!PageChecked(page))
1506 ubifs_convert_page_budget(c);
1507 SetPagePrivate(page);
1508 atomic_long_inc(&c->dirty_pg_cnt);
1509 __set_page_dirty_nobuffers(page);
1510 }
1511
1512 if (update_time) {
1513 int release;
1514 struct ubifs_inode *ui = ubifs_inode(inode);
1515
1516 mutex_lock(&ui->ui_mutex);
1517 inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1518 release = ui->dirty;
1519 mark_inode_dirty_sync(inode);
1520 mutex_unlock(&ui->ui_mutex);
1521 if (release)
1522 ubifs_release_dirty_inode_budget(c, ui);
1523 }
1524
1525 unlock_page(page);
1526 return 0;
1527
1528out_unlock:
1529 unlock_page(page);
1530 ubifs_release_budget(c, &req);
1531 if (err)
1532 err = VM_FAULT_SIGBUS;
1533 return err;
1534}
1535
1536static const struct vm_operations_struct ubifs_file_vm_ops = {
1537 .fault = filemap_fault,
1538 .page_mkwrite = ubifs_vm_page_mkwrite,
1539};
1540
1541static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
1542{
1543 int err;
1544
1545 err = generic_file_mmap(file, vma);
1546 if (err)
1547 return err;
1548 vma->vm_ops = &ubifs_file_vm_ops;
1549 return 0;
1550}
1551
1552const struct address_space_operations ubifs_file_address_operations = {
1553 .readpage = ubifs_readpage,
1554 .writepage = ubifs_writepage,
1555 .write_begin = ubifs_write_begin,
1556 .write_end = ubifs_write_end,
1557 .invalidatepage = ubifs_invalidatepage,
1558 .set_page_dirty = ubifs_set_page_dirty,
1559 .releasepage = ubifs_releasepage,
1560};
1561
1562const struct inode_operations ubifs_file_inode_operations = {
1563 .setattr = ubifs_setattr,
1564 .getattr = ubifs_getattr,
1565 .setxattr = ubifs_setxattr,
1566 .getxattr = ubifs_getxattr,
1567 .listxattr = ubifs_listxattr,
1568 .removexattr = ubifs_removexattr,
1569};
1570
1571const struct inode_operations ubifs_symlink_inode_operations = {
1572 .readlink = generic_readlink,
1573 .follow_link = ubifs_follow_link,
1574 .setattr = ubifs_setattr,
1575 .getattr = ubifs_getattr,
1576};
1577
1578const struct file_operations ubifs_file_operations = {
1579 .llseek = generic_file_llseek,
1580 .read = do_sync_read,
1581 .write = do_sync_write,
1582 .aio_read = generic_file_aio_read,
1583 .aio_write = ubifs_aio_write,
1584 .mmap = ubifs_file_mmap,
1585 .fsync = ubifs_fsync,
1586 .unlocked_ioctl = ubifs_ioctl,
1587 .splice_read = generic_file_splice_read,
1588 .splice_write = generic_file_splice_write,
1589#ifdef CONFIG_COMPAT
1590 .compat_ioctl = ubifs_compat_ioctl,
1591#endif
1592};