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Merge branch 'spi/merge' of git://git.secretlab.ca/git/linux-2.6
[deliverable/linux.git] / fs / btrfs / file.c
1 /*
2 * Copyright (C) 2007 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/fs.h>
20 #include <linux/pagemap.h>
21 #include <linux/highmem.h>
22 #include <linux/time.h>
23 #include <linux/init.h>
24 #include <linux/string.h>
25 #include <linux/backing-dev.h>
26 #include <linux/mpage.h>
27 #include <linux/falloc.h>
28 #include <linux/swap.h>
29 #include <linux/writeback.h>
30 #include <linux/statfs.h>
31 #include <linux/compat.h>
32 #include <linux/slab.h>
33 #include "ctree.h"
34 #include "disk-io.h"
35 #include "transaction.h"
36 #include "btrfs_inode.h"
37 #include "ioctl.h"
38 #include "print-tree.h"
39 #include "tree-log.h"
40 #include "locking.h"
41 #include "compat.h"
42
43
44 /* simple helper to fault in pages and copy. This should go away
45 * and be replaced with calls into generic code.
46 */
47 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
48 int write_bytes,
49 struct page **prepared_pages,
50 struct iov_iter *i)
51 {
52 size_t copied = 0;
53 int pg = 0;
54 int offset = pos & (PAGE_CACHE_SIZE - 1);
55 int total_copied = 0;
56
57 while (write_bytes > 0) {
58 size_t count = min_t(size_t,
59 PAGE_CACHE_SIZE - offset, write_bytes);
60 struct page *page = prepared_pages[pg];
61 /*
62 * Copy data from userspace to the current page
63 *
64 * Disable pagefault to avoid recursive lock since
65 * the pages are already locked
66 */
67 pagefault_disable();
68 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
69 pagefault_enable();
70
71 /* Flush processor's dcache for this page */
72 flush_dcache_page(page);
73 iov_iter_advance(i, copied);
74 write_bytes -= copied;
75 total_copied += copied;
76
77 /* Return to btrfs_file_aio_write to fault page */
78 if (unlikely(copied == 0)) {
79 break;
80 }
81
82 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
83 offset += copied;
84 } else {
85 pg++;
86 offset = 0;
87 }
88 }
89 return total_copied;
90 }
91
92 /*
93 * unlocks pages after btrfs_file_write is done with them
94 */
95 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
96 {
97 size_t i;
98 for (i = 0; i < num_pages; i++) {
99 if (!pages[i])
100 break;
101 /* page checked is some magic around finding pages that
102 * have been modified without going through btrfs_set_page_dirty
103 * clear it here
104 */
105 ClearPageChecked(pages[i]);
106 unlock_page(pages[i]);
107 mark_page_accessed(pages[i]);
108 page_cache_release(pages[i]);
109 }
110 }
111
112 /*
113 * after copy_from_user, pages need to be dirtied and we need to make
114 * sure holes are created between the current EOF and the start of
115 * any next extents (if required).
116 *
117 * this also makes the decision about creating an inline extent vs
118 * doing real data extents, marking pages dirty and delalloc as required.
119 */
120 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
121 struct btrfs_root *root,
122 struct file *file,
123 struct page **pages,
124 size_t num_pages,
125 loff_t pos,
126 size_t write_bytes)
127 {
128 int err = 0;
129 int i;
130 struct inode *inode = fdentry(file)->d_inode;
131 u64 num_bytes;
132 u64 start_pos;
133 u64 end_of_last_block;
134 u64 end_pos = pos + write_bytes;
135 loff_t isize = i_size_read(inode);
136
137 start_pos = pos & ~((u64)root->sectorsize - 1);
138 num_bytes = (write_bytes + pos - start_pos +
139 root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
140
141 end_of_last_block = start_pos + num_bytes - 1;
142 err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
143 NULL);
144 BUG_ON(err);
145
146 for (i = 0; i < num_pages; i++) {
147 struct page *p = pages[i];
148 SetPageUptodate(p);
149 ClearPageChecked(p);
150 set_page_dirty(p);
151 }
152 if (end_pos > isize) {
153 i_size_write(inode, end_pos);
154 /* we've only changed i_size in ram, and we haven't updated
155 * the disk i_size. There is no need to log the inode
156 * at this time.
157 */
158 }
159 return 0;
160 }
161
162 /*
163 * this drops all the extents in the cache that intersect the range
164 * [start, end]. Existing extents are split as required.
165 */
166 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
167 int skip_pinned)
168 {
169 struct extent_map *em;
170 struct extent_map *split = NULL;
171 struct extent_map *split2 = NULL;
172 struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
173 u64 len = end - start + 1;
174 int ret;
175 int testend = 1;
176 unsigned long flags;
177 int compressed = 0;
178
179 WARN_ON(end < start);
180 if (end == (u64)-1) {
181 len = (u64)-1;
182 testend = 0;
183 }
184 while (1) {
185 if (!split)
186 split = alloc_extent_map(GFP_NOFS);
187 if (!split2)
188 split2 = alloc_extent_map(GFP_NOFS);
189
190 write_lock(&em_tree->lock);
191 em = lookup_extent_mapping(em_tree, start, len);
192 if (!em) {
193 write_unlock(&em_tree->lock);
194 break;
195 }
196 flags = em->flags;
197 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
198 if (testend && em->start + em->len >= start + len) {
199 free_extent_map(em);
200 write_unlock(&em_tree->lock);
201 break;
202 }
203 start = em->start + em->len;
204 if (testend)
205 len = start + len - (em->start + em->len);
206 free_extent_map(em);
207 write_unlock(&em_tree->lock);
208 continue;
209 }
210 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
211 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
212 remove_extent_mapping(em_tree, em);
213
214 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
215 em->start < start) {
216 split->start = em->start;
217 split->len = start - em->start;
218 split->orig_start = em->orig_start;
219 split->block_start = em->block_start;
220
221 if (compressed)
222 split->block_len = em->block_len;
223 else
224 split->block_len = split->len;
225
226 split->bdev = em->bdev;
227 split->flags = flags;
228 split->compress_type = em->compress_type;
229 ret = add_extent_mapping(em_tree, split);
230 BUG_ON(ret);
231 free_extent_map(split);
232 split = split2;
233 split2 = NULL;
234 }
235 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
236 testend && em->start + em->len > start + len) {
237 u64 diff = start + len - em->start;
238
239 split->start = start + len;
240 split->len = em->start + em->len - (start + len);
241 split->bdev = em->bdev;
242 split->flags = flags;
243 split->compress_type = em->compress_type;
244
245 if (compressed) {
246 split->block_len = em->block_len;
247 split->block_start = em->block_start;
248 split->orig_start = em->orig_start;
249 } else {
250 split->block_len = split->len;
251 split->block_start = em->block_start + diff;
252 split->orig_start = split->start;
253 }
254
255 ret = add_extent_mapping(em_tree, split);
256 BUG_ON(ret);
257 free_extent_map(split);
258 split = NULL;
259 }
260 write_unlock(&em_tree->lock);
261
262 /* once for us */
263 free_extent_map(em);
264 /* once for the tree*/
265 free_extent_map(em);
266 }
267 if (split)
268 free_extent_map(split);
269 if (split2)
270 free_extent_map(split2);
271 return 0;
272 }
273
274 /*
275 * this is very complex, but the basic idea is to drop all extents
276 * in the range start - end. hint_block is filled in with a block number
277 * that would be a good hint to the block allocator for this file.
278 *
279 * If an extent intersects the range but is not entirely inside the range
280 * it is either truncated or split. Anything entirely inside the range
281 * is deleted from the tree.
282 */
283 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
284 u64 start, u64 end, u64 *hint_byte, int drop_cache)
285 {
286 struct btrfs_root *root = BTRFS_I(inode)->root;
287 struct extent_buffer *leaf;
288 struct btrfs_file_extent_item *fi;
289 struct btrfs_path *path;
290 struct btrfs_key key;
291 struct btrfs_key new_key;
292 u64 search_start = start;
293 u64 disk_bytenr = 0;
294 u64 num_bytes = 0;
295 u64 extent_offset = 0;
296 u64 extent_end = 0;
297 int del_nr = 0;
298 int del_slot = 0;
299 int extent_type;
300 int recow;
301 int ret;
302
303 if (drop_cache)
304 btrfs_drop_extent_cache(inode, start, end - 1, 0);
305
306 path = btrfs_alloc_path();
307 if (!path)
308 return -ENOMEM;
309
310 while (1) {
311 recow = 0;
312 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
313 search_start, -1);
314 if (ret < 0)
315 break;
316 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
317 leaf = path->nodes[0];
318 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
319 if (key.objectid == inode->i_ino &&
320 key.type == BTRFS_EXTENT_DATA_KEY)
321 path->slots[0]--;
322 }
323 ret = 0;
324 next_slot:
325 leaf = path->nodes[0];
326 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
327 BUG_ON(del_nr > 0);
328 ret = btrfs_next_leaf(root, path);
329 if (ret < 0)
330 break;
331 if (ret > 0) {
332 ret = 0;
333 break;
334 }
335 leaf = path->nodes[0];
336 recow = 1;
337 }
338
339 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
340 if (key.objectid > inode->i_ino ||
341 key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
342 break;
343
344 fi = btrfs_item_ptr(leaf, path->slots[0],
345 struct btrfs_file_extent_item);
346 extent_type = btrfs_file_extent_type(leaf, fi);
347
348 if (extent_type == BTRFS_FILE_EXTENT_REG ||
349 extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
350 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
351 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
352 extent_offset = btrfs_file_extent_offset(leaf, fi);
353 extent_end = key.offset +
354 btrfs_file_extent_num_bytes(leaf, fi);
355 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
356 extent_end = key.offset +
357 btrfs_file_extent_inline_len(leaf, fi);
358 } else {
359 WARN_ON(1);
360 extent_end = search_start;
361 }
362
363 if (extent_end <= search_start) {
364 path->slots[0]++;
365 goto next_slot;
366 }
367
368 search_start = max(key.offset, start);
369 if (recow) {
370 btrfs_release_path(root, path);
371 continue;
372 }
373
374 /*
375 * | - range to drop - |
376 * | -------- extent -------- |
377 */
378 if (start > key.offset && end < extent_end) {
379 BUG_ON(del_nr > 0);
380 BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
381
382 memcpy(&new_key, &key, sizeof(new_key));
383 new_key.offset = start;
384 ret = btrfs_duplicate_item(trans, root, path,
385 &new_key);
386 if (ret == -EAGAIN) {
387 btrfs_release_path(root, path);
388 continue;
389 }
390 if (ret < 0)
391 break;
392
393 leaf = path->nodes[0];
394 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
395 struct btrfs_file_extent_item);
396 btrfs_set_file_extent_num_bytes(leaf, fi,
397 start - key.offset);
398
399 fi = btrfs_item_ptr(leaf, path->slots[0],
400 struct btrfs_file_extent_item);
401
402 extent_offset += start - key.offset;
403 btrfs_set_file_extent_offset(leaf, fi, extent_offset);
404 btrfs_set_file_extent_num_bytes(leaf, fi,
405 extent_end - start);
406 btrfs_mark_buffer_dirty(leaf);
407
408 if (disk_bytenr > 0) {
409 ret = btrfs_inc_extent_ref(trans, root,
410 disk_bytenr, num_bytes, 0,
411 root->root_key.objectid,
412 new_key.objectid,
413 start - extent_offset);
414 BUG_ON(ret);
415 *hint_byte = disk_bytenr;
416 }
417 key.offset = start;
418 }
419 /*
420 * | ---- range to drop ----- |
421 * | -------- extent -------- |
422 */
423 if (start <= key.offset && end < extent_end) {
424 BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
425
426 memcpy(&new_key, &key, sizeof(new_key));
427 new_key.offset = end;
428 btrfs_set_item_key_safe(trans, root, path, &new_key);
429
430 extent_offset += end - key.offset;
431 btrfs_set_file_extent_offset(leaf, fi, extent_offset);
432 btrfs_set_file_extent_num_bytes(leaf, fi,
433 extent_end - end);
434 btrfs_mark_buffer_dirty(leaf);
435 if (disk_bytenr > 0) {
436 inode_sub_bytes(inode, end - key.offset);
437 *hint_byte = disk_bytenr;
438 }
439 break;
440 }
441
442 search_start = extent_end;
443 /*
444 * | ---- range to drop ----- |
445 * | -------- extent -------- |
446 */
447 if (start > key.offset && end >= extent_end) {
448 BUG_ON(del_nr > 0);
449 BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
450
451 btrfs_set_file_extent_num_bytes(leaf, fi,
452 start - key.offset);
453 btrfs_mark_buffer_dirty(leaf);
454 if (disk_bytenr > 0) {
455 inode_sub_bytes(inode, extent_end - start);
456 *hint_byte = disk_bytenr;
457 }
458 if (end == extent_end)
459 break;
460
461 path->slots[0]++;
462 goto next_slot;
463 }
464
465 /*
466 * | ---- range to drop ----- |
467 * | ------ extent ------ |
468 */
469 if (start <= key.offset && end >= extent_end) {
470 if (del_nr == 0) {
471 del_slot = path->slots[0];
472 del_nr = 1;
473 } else {
474 BUG_ON(del_slot + del_nr != path->slots[0]);
475 del_nr++;
476 }
477
478 if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
479 inode_sub_bytes(inode,
480 extent_end - key.offset);
481 extent_end = ALIGN(extent_end,
482 root->sectorsize);
483 } else if (disk_bytenr > 0) {
484 ret = btrfs_free_extent(trans, root,
485 disk_bytenr, num_bytes, 0,
486 root->root_key.objectid,
487 key.objectid, key.offset -
488 extent_offset);
489 BUG_ON(ret);
490 inode_sub_bytes(inode,
491 extent_end - key.offset);
492 *hint_byte = disk_bytenr;
493 }
494
495 if (end == extent_end)
496 break;
497
498 if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
499 path->slots[0]++;
500 goto next_slot;
501 }
502
503 ret = btrfs_del_items(trans, root, path, del_slot,
504 del_nr);
505 BUG_ON(ret);
506
507 del_nr = 0;
508 del_slot = 0;
509
510 btrfs_release_path(root, path);
511 continue;
512 }
513
514 BUG_ON(1);
515 }
516
517 if (del_nr > 0) {
518 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
519 BUG_ON(ret);
520 }
521
522 btrfs_free_path(path);
523 return ret;
524 }
525
526 static int extent_mergeable(struct extent_buffer *leaf, int slot,
527 u64 objectid, u64 bytenr, u64 orig_offset,
528 u64 *start, u64 *end)
529 {
530 struct btrfs_file_extent_item *fi;
531 struct btrfs_key key;
532 u64 extent_end;
533
534 if (slot < 0 || slot >= btrfs_header_nritems(leaf))
535 return 0;
536
537 btrfs_item_key_to_cpu(leaf, &key, slot);
538 if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
539 return 0;
540
541 fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
542 if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
543 btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
544 btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
545 btrfs_file_extent_compression(leaf, fi) ||
546 btrfs_file_extent_encryption(leaf, fi) ||
547 btrfs_file_extent_other_encoding(leaf, fi))
548 return 0;
549
550 extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
551 if ((*start && *start != key.offset) || (*end && *end != extent_end))
552 return 0;
553
554 *start = key.offset;
555 *end = extent_end;
556 return 1;
557 }
558
559 /*
560 * Mark extent in the range start - end as written.
561 *
562 * This changes extent type from 'pre-allocated' to 'regular'. If only
563 * part of extent is marked as written, the extent will be split into
564 * two or three.
565 */
566 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
567 struct inode *inode, u64 start, u64 end)
568 {
569 struct btrfs_root *root = BTRFS_I(inode)->root;
570 struct extent_buffer *leaf;
571 struct btrfs_path *path;
572 struct btrfs_file_extent_item *fi;
573 struct btrfs_key key;
574 struct btrfs_key new_key;
575 u64 bytenr;
576 u64 num_bytes;
577 u64 extent_end;
578 u64 orig_offset;
579 u64 other_start;
580 u64 other_end;
581 u64 split;
582 int del_nr = 0;
583 int del_slot = 0;
584 int recow;
585 int ret;
586
587 btrfs_drop_extent_cache(inode, start, end - 1, 0);
588
589 path = btrfs_alloc_path();
590 BUG_ON(!path);
591 again:
592 recow = 0;
593 split = start;
594 key.objectid = inode->i_ino;
595 key.type = BTRFS_EXTENT_DATA_KEY;
596 key.offset = split;
597
598 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
599 if (ret > 0 && path->slots[0] > 0)
600 path->slots[0]--;
601
602 leaf = path->nodes[0];
603 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
604 BUG_ON(key.objectid != inode->i_ino ||
605 key.type != BTRFS_EXTENT_DATA_KEY);
606 fi = btrfs_item_ptr(leaf, path->slots[0],
607 struct btrfs_file_extent_item);
608 BUG_ON(btrfs_file_extent_type(leaf, fi) !=
609 BTRFS_FILE_EXTENT_PREALLOC);
610 extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
611 BUG_ON(key.offset > start || extent_end < end);
612
613 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
614 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
615 orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
616 memcpy(&new_key, &key, sizeof(new_key));
617
618 if (start == key.offset && end < extent_end) {
619 other_start = 0;
620 other_end = start;
621 if (extent_mergeable(leaf, path->slots[0] - 1,
622 inode->i_ino, bytenr, orig_offset,
623 &other_start, &other_end)) {
624 new_key.offset = end;
625 btrfs_set_item_key_safe(trans, root, path, &new_key);
626 fi = btrfs_item_ptr(leaf, path->slots[0],
627 struct btrfs_file_extent_item);
628 btrfs_set_file_extent_num_bytes(leaf, fi,
629 extent_end - end);
630 btrfs_set_file_extent_offset(leaf, fi,
631 end - orig_offset);
632 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
633 struct btrfs_file_extent_item);
634 btrfs_set_file_extent_num_bytes(leaf, fi,
635 end - other_start);
636 btrfs_mark_buffer_dirty(leaf);
637 goto out;
638 }
639 }
640
641 if (start > key.offset && end == extent_end) {
642 other_start = end;
643 other_end = 0;
644 if (extent_mergeable(leaf, path->slots[0] + 1,
645 inode->i_ino, bytenr, orig_offset,
646 &other_start, &other_end)) {
647 fi = btrfs_item_ptr(leaf, path->slots[0],
648 struct btrfs_file_extent_item);
649 btrfs_set_file_extent_num_bytes(leaf, fi,
650 start - key.offset);
651 path->slots[0]++;
652 new_key.offset = start;
653 btrfs_set_item_key_safe(trans, root, path, &new_key);
654
655 fi = btrfs_item_ptr(leaf, path->slots[0],
656 struct btrfs_file_extent_item);
657 btrfs_set_file_extent_num_bytes(leaf, fi,
658 other_end - start);
659 btrfs_set_file_extent_offset(leaf, fi,
660 start - orig_offset);
661 btrfs_mark_buffer_dirty(leaf);
662 goto out;
663 }
664 }
665
666 while (start > key.offset || end < extent_end) {
667 if (key.offset == start)
668 split = end;
669
670 new_key.offset = split;
671 ret = btrfs_duplicate_item(trans, root, path, &new_key);
672 if (ret == -EAGAIN) {
673 btrfs_release_path(root, path);
674 goto again;
675 }
676 BUG_ON(ret < 0);
677
678 leaf = path->nodes[0];
679 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
680 struct btrfs_file_extent_item);
681 btrfs_set_file_extent_num_bytes(leaf, fi,
682 split - key.offset);
683
684 fi = btrfs_item_ptr(leaf, path->slots[0],
685 struct btrfs_file_extent_item);
686
687 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
688 btrfs_set_file_extent_num_bytes(leaf, fi,
689 extent_end - split);
690 btrfs_mark_buffer_dirty(leaf);
691
692 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
693 root->root_key.objectid,
694 inode->i_ino, orig_offset);
695 BUG_ON(ret);
696
697 if (split == start) {
698 key.offset = start;
699 } else {
700 BUG_ON(start != key.offset);
701 path->slots[0]--;
702 extent_end = end;
703 }
704 recow = 1;
705 }
706
707 other_start = end;
708 other_end = 0;
709 if (extent_mergeable(leaf, path->slots[0] + 1,
710 inode->i_ino, bytenr, orig_offset,
711 &other_start, &other_end)) {
712 if (recow) {
713 btrfs_release_path(root, path);
714 goto again;
715 }
716 extent_end = other_end;
717 del_slot = path->slots[0] + 1;
718 del_nr++;
719 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
720 0, root->root_key.objectid,
721 inode->i_ino, orig_offset);
722 BUG_ON(ret);
723 }
724 other_start = 0;
725 other_end = start;
726 if (extent_mergeable(leaf, path->slots[0] - 1,
727 inode->i_ino, bytenr, orig_offset,
728 &other_start, &other_end)) {
729 if (recow) {
730 btrfs_release_path(root, path);
731 goto again;
732 }
733 key.offset = other_start;
734 del_slot = path->slots[0];
735 del_nr++;
736 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
737 0, root->root_key.objectid,
738 inode->i_ino, orig_offset);
739 BUG_ON(ret);
740 }
741 if (del_nr == 0) {
742 fi = btrfs_item_ptr(leaf, path->slots[0],
743 struct btrfs_file_extent_item);
744 btrfs_set_file_extent_type(leaf, fi,
745 BTRFS_FILE_EXTENT_REG);
746 btrfs_mark_buffer_dirty(leaf);
747 } else {
748 fi = btrfs_item_ptr(leaf, del_slot - 1,
749 struct btrfs_file_extent_item);
750 btrfs_set_file_extent_type(leaf, fi,
751 BTRFS_FILE_EXTENT_REG);
752 btrfs_set_file_extent_num_bytes(leaf, fi,
753 extent_end - key.offset);
754 btrfs_mark_buffer_dirty(leaf);
755
756 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
757 BUG_ON(ret);
758 }
759 out:
760 btrfs_free_path(path);
761 return 0;
762 }
763
764 /*
765 * this gets pages into the page cache and locks them down, it also properly
766 * waits for data=ordered extents to finish before allowing the pages to be
767 * modified.
768 */
769 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
770 struct page **pages, size_t num_pages,
771 loff_t pos, unsigned long first_index,
772 unsigned long last_index, size_t write_bytes)
773 {
774 struct extent_state *cached_state = NULL;
775 int i;
776 unsigned long index = pos >> PAGE_CACHE_SHIFT;
777 struct inode *inode = fdentry(file)->d_inode;
778 int err = 0;
779 u64 start_pos;
780 u64 last_pos;
781
782 start_pos = pos & ~((u64)root->sectorsize - 1);
783 last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
784
785 if (start_pos > inode->i_size) {
786 err = btrfs_cont_expand(inode, start_pos);
787 if (err)
788 return err;
789 }
790
791 memset(pages, 0, num_pages * sizeof(struct page *));
792 again:
793 for (i = 0; i < num_pages; i++) {
794 pages[i] = grab_cache_page(inode->i_mapping, index + i);
795 if (!pages[i]) {
796 int c;
797 for (c = i - 1; c >= 0; c--) {
798 unlock_page(pages[c]);
799 page_cache_release(pages[c]);
800 }
801 return -ENOMEM;
802 }
803 wait_on_page_writeback(pages[i]);
804 }
805 if (start_pos < inode->i_size) {
806 struct btrfs_ordered_extent *ordered;
807 lock_extent_bits(&BTRFS_I(inode)->io_tree,
808 start_pos, last_pos - 1, 0, &cached_state,
809 GFP_NOFS);
810 ordered = btrfs_lookup_first_ordered_extent(inode,
811 last_pos - 1);
812 if (ordered &&
813 ordered->file_offset + ordered->len > start_pos &&
814 ordered->file_offset < last_pos) {
815 btrfs_put_ordered_extent(ordered);
816 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
817 start_pos, last_pos - 1,
818 &cached_state, GFP_NOFS);
819 for (i = 0; i < num_pages; i++) {
820 unlock_page(pages[i]);
821 page_cache_release(pages[i]);
822 }
823 btrfs_wait_ordered_range(inode, start_pos,
824 last_pos - start_pos);
825 goto again;
826 }
827 if (ordered)
828 btrfs_put_ordered_extent(ordered);
829
830 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
831 last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
832 EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
833 GFP_NOFS);
834 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
835 start_pos, last_pos - 1, &cached_state,
836 GFP_NOFS);
837 }
838 for (i = 0; i < num_pages; i++) {
839 clear_page_dirty_for_io(pages[i]);
840 set_page_extent_mapped(pages[i]);
841 WARN_ON(!PageLocked(pages[i]));
842 }
843 return 0;
844 }
845
846 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
847 const struct iovec *iov,
848 unsigned long nr_segs, loff_t pos)
849 {
850 struct file *file = iocb->ki_filp;
851 struct inode *inode = fdentry(file)->d_inode;
852 struct btrfs_root *root = BTRFS_I(inode)->root;
853 struct page *pinned[2];
854 struct page **pages = NULL;
855 struct iov_iter i;
856 loff_t *ppos = &iocb->ki_pos;
857 loff_t start_pos;
858 ssize_t num_written = 0;
859 ssize_t err = 0;
860 size_t count;
861 size_t ocount;
862 int ret = 0;
863 int nrptrs;
864 unsigned long first_index;
865 unsigned long last_index;
866 int will_write;
867 int buffered = 0;
868 int copied = 0;
869 int dirty_pages = 0;
870
871 will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
872 (file->f_flags & O_DIRECT));
873
874 pinned[0] = NULL;
875 pinned[1] = NULL;
876
877 start_pos = pos;
878
879 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
880
881 mutex_lock(&inode->i_mutex);
882
883 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
884 if (err)
885 goto out;
886 count = ocount;
887
888 current->backing_dev_info = inode->i_mapping->backing_dev_info;
889 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
890 if (err)
891 goto out;
892
893 if (count == 0)
894 goto out;
895
896 err = file_remove_suid(file);
897 if (err)
898 goto out;
899
900 /*
901 * If BTRFS flips readonly due to some impossible error
902 * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
903 * although we have opened a file as writable, we have
904 * to stop this write operation to ensure FS consistency.
905 */
906 if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
907 err = -EROFS;
908 goto out;
909 }
910
911 file_update_time(file);
912 BTRFS_I(inode)->sequence++;
913
914 if (unlikely(file->f_flags & O_DIRECT)) {
915 num_written = generic_file_direct_write(iocb, iov, &nr_segs,
916 pos, ppos, count,
917 ocount);
918 /*
919 * the generic O_DIRECT will update in-memory i_size after the
920 * DIOs are done. But our endio handlers that update the on
921 * disk i_size never update past the in memory i_size. So we
922 * need one more update here to catch any additions to the
923 * file
924 */
925 if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
926 btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
927 mark_inode_dirty(inode);
928 }
929
930 if (num_written < 0) {
931 ret = num_written;
932 num_written = 0;
933 goto out;
934 } else if (num_written == count) {
935 /* pick up pos changes done by the generic code */
936 pos = *ppos;
937 goto out;
938 }
939 /*
940 * We are going to do buffered for the rest of the range, so we
941 * need to make sure to invalidate the buffered pages when we're
942 * done.
943 */
944 buffered = 1;
945 pos += num_written;
946 }
947
948 iov_iter_init(&i, iov, nr_segs, count, num_written);
949 nrptrs = min((iov_iter_count(&i) + PAGE_CACHE_SIZE - 1) /
950 PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
951 (sizeof(struct page *)));
952 pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
953 if (!pages) {
954 ret = -ENOMEM;
955 goto out;
956 }
957
958 /* generic_write_checks can change our pos */
959 start_pos = pos;
960
961 first_index = pos >> PAGE_CACHE_SHIFT;
962 last_index = (pos + iov_iter_count(&i)) >> PAGE_CACHE_SHIFT;
963
964 /*
965 * there are lots of better ways to do this, but this code
966 * makes sure the first and last page in the file range are
967 * up to date and ready for cow
968 */
969 if ((pos & (PAGE_CACHE_SIZE - 1))) {
970 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
971 if (!PageUptodate(pinned[0])) {
972 ret = btrfs_readpage(NULL, pinned[0]);
973 BUG_ON(ret);
974 wait_on_page_locked(pinned[0]);
975 } else {
976 unlock_page(pinned[0]);
977 }
978 }
979 if ((pos + iov_iter_count(&i)) & (PAGE_CACHE_SIZE - 1)) {
980 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
981 if (!PageUptodate(pinned[1])) {
982 ret = btrfs_readpage(NULL, pinned[1]);
983 BUG_ON(ret);
984 wait_on_page_locked(pinned[1]);
985 } else {
986 unlock_page(pinned[1]);
987 }
988 }
989
990 while (iov_iter_count(&i) > 0) {
991 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
992 size_t write_bytes = min(iov_iter_count(&i),
993 nrptrs * (size_t)PAGE_CACHE_SIZE -
994 offset);
995 size_t num_pages = (write_bytes + offset +
996 PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
997
998 WARN_ON(num_pages > nrptrs);
999 memset(pages, 0, sizeof(struct page *) * nrptrs);
1000
1001 /*
1002 * Fault pages before locking them in prepare_pages
1003 * to avoid recursive lock
1004 */
1005 if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) {
1006 ret = -EFAULT;
1007 goto out;
1008 }
1009
1010 ret = btrfs_delalloc_reserve_space(inode,
1011 num_pages << PAGE_CACHE_SHIFT);
1012 if (ret)
1013 goto out;
1014
1015 ret = prepare_pages(root, file, pages, num_pages,
1016 pos, first_index, last_index,
1017 write_bytes);
1018 if (ret) {
1019 btrfs_delalloc_release_space(inode,
1020 num_pages << PAGE_CACHE_SHIFT);
1021 goto out;
1022 }
1023
1024 copied = btrfs_copy_from_user(pos, num_pages,
1025 write_bytes, pages, &i);
1026 dirty_pages = (copied + offset + PAGE_CACHE_SIZE - 1) >>
1027 PAGE_CACHE_SHIFT;
1028
1029 if (num_pages > dirty_pages) {
1030 if (copied > 0)
1031 atomic_inc(
1032 &BTRFS_I(inode)->outstanding_extents);
1033 btrfs_delalloc_release_space(inode,
1034 (num_pages - dirty_pages) <<
1035 PAGE_CACHE_SHIFT);
1036 }
1037
1038 if (copied > 0) {
1039 dirty_and_release_pages(NULL, root, file, pages,
1040 dirty_pages, pos, copied);
1041 }
1042
1043 btrfs_drop_pages(pages, num_pages);
1044
1045 if (copied > 0) {
1046 if (will_write) {
1047 filemap_fdatawrite_range(inode->i_mapping, pos,
1048 pos + copied - 1);
1049 } else {
1050 balance_dirty_pages_ratelimited_nr(
1051 inode->i_mapping,
1052 dirty_pages);
1053 if (dirty_pages <
1054 (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1055 btrfs_btree_balance_dirty(root, 1);
1056 btrfs_throttle(root);
1057 }
1058 }
1059
1060 pos += copied;
1061 num_written += copied;
1062
1063 cond_resched();
1064 }
1065 out:
1066 mutex_unlock(&inode->i_mutex);
1067 if (ret)
1068 err = ret;
1069
1070 kfree(pages);
1071 if (pinned[0])
1072 page_cache_release(pinned[0]);
1073 if (pinned[1])
1074 page_cache_release(pinned[1]);
1075 *ppos = pos;
1076
1077 /*
1078 * we want to make sure fsync finds this change
1079 * but we haven't joined a transaction running right now.
1080 *
1081 * Later on, someone is sure to update the inode and get the
1082 * real transid recorded.
1083 *
1084 * We set last_trans now to the fs_info generation + 1,
1085 * this will either be one more than the running transaction
1086 * or the generation used for the next transaction if there isn't
1087 * one running right now.
1088 */
1089 BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1090
1091 if (num_written > 0 && will_write) {
1092 struct btrfs_trans_handle *trans;
1093
1094 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1095 if (err)
1096 num_written = err;
1097
1098 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1099 trans = btrfs_start_transaction(root, 0);
1100 if (IS_ERR(trans)) {
1101 num_written = PTR_ERR(trans);
1102 goto done;
1103 }
1104 mutex_lock(&inode->i_mutex);
1105 ret = btrfs_log_dentry_safe(trans, root,
1106 file->f_dentry);
1107 mutex_unlock(&inode->i_mutex);
1108 if (ret == 0) {
1109 ret = btrfs_sync_log(trans, root);
1110 if (ret == 0)
1111 btrfs_end_transaction(trans, root);
1112 else
1113 btrfs_commit_transaction(trans, root);
1114 } else if (ret != BTRFS_NO_LOG_SYNC) {
1115 btrfs_commit_transaction(trans, root);
1116 } else {
1117 btrfs_end_transaction(trans, root);
1118 }
1119 }
1120 if (file->f_flags & O_DIRECT && buffered) {
1121 invalidate_mapping_pages(inode->i_mapping,
1122 start_pos >> PAGE_CACHE_SHIFT,
1123 (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1124 }
1125 }
1126 done:
1127 current->backing_dev_info = NULL;
1128 return num_written ? num_written : err;
1129 }
1130
1131 int btrfs_release_file(struct inode *inode, struct file *filp)
1132 {
1133 /*
1134 * ordered_data_close is set by settattr when we are about to truncate
1135 * a file from a non-zero size to a zero size. This tries to
1136 * flush down new bytes that may have been written if the
1137 * application were using truncate to replace a file in place.
1138 */
1139 if (BTRFS_I(inode)->ordered_data_close) {
1140 BTRFS_I(inode)->ordered_data_close = 0;
1141 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1142 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1143 filemap_flush(inode->i_mapping);
1144 }
1145 if (filp->private_data)
1146 btrfs_ioctl_trans_end(filp);
1147 return 0;
1148 }
1149
1150 /*
1151 * fsync call for both files and directories. This logs the inode into
1152 * the tree log instead of forcing full commits whenever possible.
1153 *
1154 * It needs to call filemap_fdatawait so that all ordered extent updates are
1155 * in the metadata btree are up to date for copying to the log.
1156 *
1157 * It drops the inode mutex before doing the tree log commit. This is an
1158 * important optimization for directories because holding the mutex prevents
1159 * new operations on the dir while we write to disk.
1160 */
1161 int btrfs_sync_file(struct file *file, int datasync)
1162 {
1163 struct dentry *dentry = file->f_path.dentry;
1164 struct inode *inode = dentry->d_inode;
1165 struct btrfs_root *root = BTRFS_I(inode)->root;
1166 int ret = 0;
1167 struct btrfs_trans_handle *trans;
1168
1169
1170 /* we wait first, since the writeback may change the inode */
1171 root->log_batch++;
1172 /* the VFS called filemap_fdatawrite for us */
1173 btrfs_wait_ordered_range(inode, 0, (u64)-1);
1174 root->log_batch++;
1175
1176 /*
1177 * check the transaction that last modified this inode
1178 * and see if its already been committed
1179 */
1180 if (!BTRFS_I(inode)->last_trans)
1181 goto out;
1182
1183 /*
1184 * if the last transaction that changed this file was before
1185 * the current transaction, we can bail out now without any
1186 * syncing
1187 */
1188 mutex_lock(&root->fs_info->trans_mutex);
1189 if (BTRFS_I(inode)->last_trans <=
1190 root->fs_info->last_trans_committed) {
1191 BTRFS_I(inode)->last_trans = 0;
1192 mutex_unlock(&root->fs_info->trans_mutex);
1193 goto out;
1194 }
1195 mutex_unlock(&root->fs_info->trans_mutex);
1196
1197 /*
1198 * ok we haven't committed the transaction yet, lets do a commit
1199 */
1200 if (file->private_data)
1201 btrfs_ioctl_trans_end(file);
1202
1203 trans = btrfs_start_transaction(root, 0);
1204 if (IS_ERR(trans)) {
1205 ret = PTR_ERR(trans);
1206 goto out;
1207 }
1208
1209 ret = btrfs_log_dentry_safe(trans, root, dentry);
1210 if (ret < 0)
1211 goto out;
1212
1213 /* we've logged all the items and now have a consistent
1214 * version of the file in the log. It is possible that
1215 * someone will come in and modify the file, but that's
1216 * fine because the log is consistent on disk, and we
1217 * have references to all of the file's extents
1218 *
1219 * It is possible that someone will come in and log the
1220 * file again, but that will end up using the synchronization
1221 * inside btrfs_sync_log to keep things safe.
1222 */
1223 mutex_unlock(&dentry->d_inode->i_mutex);
1224
1225 if (ret != BTRFS_NO_LOG_SYNC) {
1226 if (ret > 0) {
1227 ret = btrfs_commit_transaction(trans, root);
1228 } else {
1229 ret = btrfs_sync_log(trans, root);
1230 if (ret == 0)
1231 ret = btrfs_end_transaction(trans, root);
1232 else
1233 ret = btrfs_commit_transaction(trans, root);
1234 }
1235 } else {
1236 ret = btrfs_end_transaction(trans, root);
1237 }
1238 mutex_lock(&dentry->d_inode->i_mutex);
1239 out:
1240 return ret > 0 ? -EIO : ret;
1241 }
1242
1243 static const struct vm_operations_struct btrfs_file_vm_ops = {
1244 .fault = filemap_fault,
1245 .page_mkwrite = btrfs_page_mkwrite,
1246 };
1247
1248 static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma)
1249 {
1250 struct address_space *mapping = filp->f_mapping;
1251
1252 if (!mapping->a_ops->readpage)
1253 return -ENOEXEC;
1254
1255 file_accessed(filp);
1256 vma->vm_ops = &btrfs_file_vm_ops;
1257 vma->vm_flags |= VM_CAN_NONLINEAR;
1258
1259 return 0;
1260 }
1261
1262 static long btrfs_fallocate(struct file *file, int mode,
1263 loff_t offset, loff_t len)
1264 {
1265 struct inode *inode = file->f_path.dentry->d_inode;
1266 struct extent_state *cached_state = NULL;
1267 u64 cur_offset;
1268 u64 last_byte;
1269 u64 alloc_start;
1270 u64 alloc_end;
1271 u64 alloc_hint = 0;
1272 u64 locked_end;
1273 u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1274 struct extent_map *em;
1275 int ret;
1276
1277 alloc_start = offset & ~mask;
1278 alloc_end = (offset + len + mask) & ~mask;
1279
1280 /* We only support the FALLOC_FL_KEEP_SIZE mode */
1281 if (mode & ~FALLOC_FL_KEEP_SIZE)
1282 return -EOPNOTSUPP;
1283
1284 /*
1285 * wait for ordered IO before we have any locks. We'll loop again
1286 * below with the locks held.
1287 */
1288 btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1289
1290 mutex_lock(&inode->i_mutex);
1291 ret = inode_newsize_ok(inode, alloc_end);
1292 if (ret)
1293 goto out;
1294
1295 if (alloc_start > inode->i_size) {
1296 ret = btrfs_cont_expand(inode, alloc_start);
1297 if (ret)
1298 goto out;
1299 }
1300
1301 ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
1302 if (ret)
1303 goto out;
1304
1305 locked_end = alloc_end - 1;
1306 while (1) {
1307 struct btrfs_ordered_extent *ordered;
1308
1309 /* the extent lock is ordered inside the running
1310 * transaction
1311 */
1312 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1313 locked_end, 0, &cached_state, GFP_NOFS);
1314 ordered = btrfs_lookup_first_ordered_extent(inode,
1315 alloc_end - 1);
1316 if (ordered &&
1317 ordered->file_offset + ordered->len > alloc_start &&
1318 ordered->file_offset < alloc_end) {
1319 btrfs_put_ordered_extent(ordered);
1320 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1321 alloc_start, locked_end,
1322 &cached_state, GFP_NOFS);
1323 /*
1324 * we can't wait on the range with the transaction
1325 * running or with the extent lock held
1326 */
1327 btrfs_wait_ordered_range(inode, alloc_start,
1328 alloc_end - alloc_start);
1329 } else {
1330 if (ordered)
1331 btrfs_put_ordered_extent(ordered);
1332 break;
1333 }
1334 }
1335
1336 cur_offset = alloc_start;
1337 while (1) {
1338 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1339 alloc_end - cur_offset, 0);
1340 BUG_ON(IS_ERR(em) || !em);
1341 last_byte = min(extent_map_end(em), alloc_end);
1342 last_byte = (last_byte + mask) & ~mask;
1343 if (em->block_start == EXTENT_MAP_HOLE ||
1344 (cur_offset >= inode->i_size &&
1345 !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1346 ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1347 last_byte - cur_offset,
1348 1 << inode->i_blkbits,
1349 offset + len,
1350 &alloc_hint);
1351 if (ret < 0) {
1352 free_extent_map(em);
1353 break;
1354 }
1355 }
1356 free_extent_map(em);
1357
1358 cur_offset = last_byte;
1359 if (cur_offset >= alloc_end) {
1360 ret = 0;
1361 break;
1362 }
1363 }
1364 unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1365 &cached_state, GFP_NOFS);
1366
1367 btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
1368 out:
1369 mutex_unlock(&inode->i_mutex);
1370 return ret;
1371 }
1372
1373 const struct file_operations btrfs_file_operations = {
1374 .llseek = generic_file_llseek,
1375 .read = do_sync_read,
1376 .write = do_sync_write,
1377 .aio_read = generic_file_aio_read,
1378 .splice_read = generic_file_splice_read,
1379 .aio_write = btrfs_file_aio_write,
1380 .mmap = btrfs_file_mmap,
1381 .open = generic_file_open,
1382 .release = btrfs_release_file,
1383 .fsync = btrfs_sync_file,
1384 .fallocate = btrfs_fallocate,
1385 .unlocked_ioctl = btrfs_ioctl,
1386 #ifdef CONFIG_COMPAT
1387 .compat_ioctl = btrfs_ioctl,
1388 #endif
1389 };
Linux kernel - Deliverables
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