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Btrfs: Fix extent replacment race
[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/smp_lock.h>
26 #include <linux/backing-dev.h>
27 #include <linux/mpage.h>
28 #include <linux/swap.h>
29 #include <linux/writeback.h>
30 #include <linux/statfs.h>
31 #include <linux/compat.h>
32 #include "ctree.h"
33 #include "disk-io.h"
34 #include "transaction.h"
35 #include "btrfs_inode.h"
36 #include "ioctl.h"
37 #include "print-tree.h"
38 #include "tree-log.h"
39 #include "locking.h"
40 #include "compat.h"
41
42
43 /* simple helper to fault in pages and copy. This should go away
44 * and be replaced with calls into generic code.
45 */
46 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
47 int write_bytes,
48 struct page **prepared_pages,
49 const char __user *buf)
50 {
51 long page_fault = 0;
52 int i;
53 int offset = pos & (PAGE_CACHE_SIZE - 1);
54
55 for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
56 size_t count = min_t(size_t,
57 PAGE_CACHE_SIZE - offset, write_bytes);
58 struct page *page = prepared_pages[i];
59 fault_in_pages_readable(buf, count);
60
61 /* Copy data from userspace to the current page */
62 kmap(page);
63 page_fault = __copy_from_user(page_address(page) + offset,
64 buf, count);
65 /* Flush processor's dcache for this page */
66 flush_dcache_page(page);
67 kunmap(page);
68 buf += count;
69 write_bytes -= count;
70
71 if (page_fault)
72 break;
73 }
74 return page_fault ? -EFAULT : 0;
75 }
76
77 /*
78 * unlocks pages after btrfs_file_write is done with them
79 */
80 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
81 {
82 size_t i;
83 for (i = 0; i < num_pages; i++) {
84 if (!pages[i])
85 break;
86 /* page checked is some magic around finding pages that
87 * have been modified without going through btrfs_set_page_dirty
88 * clear it here
89 */
90 ClearPageChecked(pages[i]);
91 unlock_page(pages[i]);
92 mark_page_accessed(pages[i]);
93 page_cache_release(pages[i]);
94 }
95 }
96
97 /*
98 * after copy_from_user, pages need to be dirtied and we need to make
99 * sure holes are created between the current EOF and the start of
100 * any next extents (if required).
101 *
102 * this also makes the decision about creating an inline extent vs
103 * doing real data extents, marking pages dirty and delalloc as required.
104 */
105 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
106 struct btrfs_root *root,
107 struct file *file,
108 struct page **pages,
109 size_t num_pages,
110 loff_t pos,
111 size_t write_bytes)
112 {
113 int err = 0;
114 int i;
115 struct inode *inode = fdentry(file)->d_inode;
116 u64 num_bytes;
117 u64 start_pos;
118 u64 end_of_last_block;
119 u64 end_pos = pos + write_bytes;
120 loff_t isize = i_size_read(inode);
121
122 start_pos = pos & ~((u64)root->sectorsize - 1);
123 num_bytes = (write_bytes + pos - start_pos +
124 root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
125
126 end_of_last_block = start_pos + num_bytes - 1;
127 btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
128 for (i = 0; i < num_pages; i++) {
129 struct page *p = pages[i];
130 SetPageUptodate(p);
131 ClearPageChecked(p);
132 set_page_dirty(p);
133 }
134 if (end_pos > isize) {
135 i_size_write(inode, end_pos);
136 /* we've only changed i_size in ram, and we haven't updated
137 * the disk i_size. There is no need to log the inode
138 * at this time.
139 */
140 }
141 return err;
142 }
143
144 /*
145 * this drops all the extents in the cache that intersect the range
146 * [start, end]. Existing extents are split as required.
147 */
148 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
149 int skip_pinned)
150 {
151 struct extent_map *em;
152 struct extent_map *split = NULL;
153 struct extent_map *split2 = NULL;
154 struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
155 u64 len = end - start + 1;
156 int ret;
157 int testend = 1;
158 unsigned long flags;
159 int compressed = 0;
160
161 WARN_ON(end < start);
162 if (end == (u64)-1) {
163 len = (u64)-1;
164 testend = 0;
165 }
166 while (1) {
167 if (!split)
168 split = alloc_extent_map(GFP_NOFS);
169 if (!split2)
170 split2 = alloc_extent_map(GFP_NOFS);
171
172 write_lock(&em_tree->lock);
173 em = lookup_extent_mapping(em_tree, start, len);
174 if (!em) {
175 write_unlock(&em_tree->lock);
176 break;
177 }
178 flags = em->flags;
179 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
180 if (em->start <= start &&
181 (!testend || em->start + em->len >= start + len)) {
182 free_extent_map(em);
183 write_unlock(&em_tree->lock);
184 break;
185 }
186 if (start < em->start) {
187 len = em->start - start;
188 } else {
189 len = start + len - (em->start + em->len);
190 start = em->start + em->len;
191 }
192 free_extent_map(em);
193 write_unlock(&em_tree->lock);
194 continue;
195 }
196 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
197 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
198 remove_extent_mapping(em_tree, em);
199
200 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
201 em->start < start) {
202 split->start = em->start;
203 split->len = start - em->start;
204 split->orig_start = em->orig_start;
205 split->block_start = em->block_start;
206
207 if (compressed)
208 split->block_len = em->block_len;
209 else
210 split->block_len = split->len;
211
212 split->bdev = em->bdev;
213 split->flags = flags;
214 ret = add_extent_mapping(em_tree, split);
215 BUG_ON(ret);
216 free_extent_map(split);
217 split = split2;
218 split2 = NULL;
219 }
220 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
221 testend && em->start + em->len > start + len) {
222 u64 diff = start + len - em->start;
223
224 split->start = start + len;
225 split->len = em->start + em->len - (start + len);
226 split->bdev = em->bdev;
227 split->flags = flags;
228
229 if (compressed) {
230 split->block_len = em->block_len;
231 split->block_start = em->block_start;
232 split->orig_start = em->orig_start;
233 } else {
234 split->block_len = split->len;
235 split->block_start = em->block_start + diff;
236 split->orig_start = split->start;
237 }
238
239 ret = add_extent_mapping(em_tree, split);
240 BUG_ON(ret);
241 free_extent_map(split);
242 split = NULL;
243 }
244 write_unlock(&em_tree->lock);
245
246 /* once for us */
247 free_extent_map(em);
248 /* once for the tree*/
249 free_extent_map(em);
250 }
251 if (split)
252 free_extent_map(split);
253 if (split2)
254 free_extent_map(split2);
255 return 0;
256 }
257
258 /*
259 * this is very complex, but the basic idea is to drop all extents
260 * in the range start - end. hint_block is filled in with a block number
261 * that would be a good hint to the block allocator for this file.
262 *
263 * If an extent intersects the range but is not entirely inside the range
264 * it is either truncated or split. Anything entirely inside the range
265 * is deleted from the tree.
266 *
267 * inline_limit is used to tell this code which offsets in the file to keep
268 * if they contain inline extents.
269 */
270 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
271 struct btrfs_root *root, struct inode *inode,
272 u64 start, u64 end, u64 locked_end,
273 u64 inline_limit, u64 *hint_byte, int drop_cache)
274 {
275 u64 extent_end = 0;
276 u64 search_start = start;
277 u64 ram_bytes = 0;
278 u64 disk_bytenr = 0;
279 u64 orig_locked_end = locked_end;
280 u8 compression;
281 u8 encryption;
282 u16 other_encoding = 0;
283 struct extent_buffer *leaf;
284 struct btrfs_file_extent_item *extent;
285 struct btrfs_path *path;
286 struct btrfs_key key;
287 struct btrfs_file_extent_item old;
288 int keep;
289 int slot;
290 int bookend;
291 int found_type = 0;
292 int found_extent;
293 int found_inline;
294 int recow;
295 int ret;
296
297 inline_limit = 0;
298 if (drop_cache)
299 btrfs_drop_extent_cache(inode, start, end - 1, 0);
300
301 path = btrfs_alloc_path();
302 if (!path)
303 return -ENOMEM;
304 while (1) {
305 recow = 0;
306 btrfs_release_path(root, path);
307 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
308 search_start, -1);
309 if (ret < 0)
310 goto out;
311 if (ret > 0) {
312 if (path->slots[0] == 0) {
313 ret = 0;
314 goto out;
315 }
316 path->slots[0]--;
317 }
318 next_slot:
319 keep = 0;
320 bookend = 0;
321 found_extent = 0;
322 found_inline = 0;
323 compression = 0;
324 encryption = 0;
325 extent = NULL;
326 leaf = path->nodes[0];
327 slot = path->slots[0];
328 ret = 0;
329 btrfs_item_key_to_cpu(leaf, &key, slot);
330 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
331 key.offset >= end) {
332 goto out;
333 }
334 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
335 key.objectid != inode->i_ino) {
336 goto out;
337 }
338 if (recow) {
339 search_start = max(key.offset, start);
340 continue;
341 }
342 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
343 extent = btrfs_item_ptr(leaf, slot,
344 struct btrfs_file_extent_item);
345 found_type = btrfs_file_extent_type(leaf, extent);
346 compression = btrfs_file_extent_compression(leaf,
347 extent);
348 encryption = btrfs_file_extent_encryption(leaf,
349 extent);
350 other_encoding = btrfs_file_extent_other_encoding(leaf,
351 extent);
352 if (found_type == BTRFS_FILE_EXTENT_REG ||
353 found_type == BTRFS_FILE_EXTENT_PREALLOC) {
354 extent_end =
355 btrfs_file_extent_disk_bytenr(leaf,
356 extent);
357 if (extent_end)
358 *hint_byte = extent_end;
359
360 extent_end = key.offset +
361 btrfs_file_extent_num_bytes(leaf, extent);
362 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
363 extent);
364 found_extent = 1;
365 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
366 found_inline = 1;
367 extent_end = key.offset +
368 btrfs_file_extent_inline_len(leaf, extent);
369 }
370 } else {
371 extent_end = search_start;
372 }
373
374 /* we found nothing we can drop */
375 if ((!found_extent && !found_inline) ||
376 search_start >= extent_end) {
377 int nextret;
378 u32 nritems;
379 nritems = btrfs_header_nritems(leaf);
380 if (slot >= nritems - 1) {
381 nextret = btrfs_next_leaf(root, path);
382 if (nextret)
383 goto out;
384 recow = 1;
385 } else {
386 path->slots[0]++;
387 }
388 goto next_slot;
389 }
390
391 if (end <= extent_end && start >= key.offset && found_inline)
392 *hint_byte = EXTENT_MAP_INLINE;
393
394 if (found_extent) {
395 read_extent_buffer(leaf, &old, (unsigned long)extent,
396 sizeof(old));
397 }
398
399 if (end < extent_end && end >= key.offset) {
400 bookend = 1;
401 if (found_inline && start <= key.offset)
402 keep = 1;
403 }
404
405 if (bookend && found_extent) {
406 if (locked_end < extent_end) {
407 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
408 locked_end, extent_end - 1,
409 GFP_NOFS);
410 if (!ret) {
411 btrfs_release_path(root, path);
412 lock_extent(&BTRFS_I(inode)->io_tree,
413 locked_end, extent_end - 1,
414 GFP_NOFS);
415 locked_end = extent_end;
416 continue;
417 }
418 locked_end = extent_end;
419 }
420 disk_bytenr = le64_to_cpu(old.disk_bytenr);
421 if (disk_bytenr != 0) {
422 ret = btrfs_inc_extent_ref(trans, root,
423 disk_bytenr,
424 le64_to_cpu(old.disk_num_bytes), 0,
425 root->root_key.objectid,
426 key.objectid, key.offset -
427 le64_to_cpu(old.offset));
428 BUG_ON(ret);
429 }
430 }
431
432 if (found_inline) {
433 u64 mask = root->sectorsize - 1;
434 search_start = (extent_end + mask) & ~mask;
435 } else
436 search_start = extent_end;
437
438 /* truncate existing extent */
439 if (start > key.offset) {
440 u64 new_num;
441 u64 old_num;
442 keep = 1;
443 WARN_ON(start & (root->sectorsize - 1));
444 if (found_extent) {
445 new_num = start - key.offset;
446 old_num = btrfs_file_extent_num_bytes(leaf,
447 extent);
448 *hint_byte =
449 btrfs_file_extent_disk_bytenr(leaf,
450 extent);
451 if (btrfs_file_extent_disk_bytenr(leaf,
452 extent)) {
453 inode_sub_bytes(inode, old_num -
454 new_num);
455 }
456 btrfs_set_file_extent_num_bytes(leaf,
457 extent, new_num);
458 btrfs_mark_buffer_dirty(leaf);
459 } else if (key.offset < inline_limit &&
460 (end > extent_end) &&
461 (inline_limit < extent_end)) {
462 u32 new_size;
463 new_size = btrfs_file_extent_calc_inline_size(
464 inline_limit - key.offset);
465 inode_sub_bytes(inode, extent_end -
466 inline_limit);
467 btrfs_set_file_extent_ram_bytes(leaf, extent,
468 new_size);
469 if (!compression && !encryption) {
470 btrfs_truncate_item(trans, root, path,
471 new_size, 1);
472 }
473 }
474 }
475 /* delete the entire extent */
476 if (!keep) {
477 if (found_inline)
478 inode_sub_bytes(inode, extent_end -
479 key.offset);
480 ret = btrfs_del_item(trans, root, path);
481 /* TODO update progress marker and return */
482 BUG_ON(ret);
483 extent = NULL;
484 btrfs_release_path(root, path);
485 /* the extent will be freed later */
486 }
487 if (bookend && found_inline && start <= key.offset) {
488 u32 new_size;
489 new_size = btrfs_file_extent_calc_inline_size(
490 extent_end - end);
491 inode_sub_bytes(inode, end - key.offset);
492 btrfs_set_file_extent_ram_bytes(leaf, extent,
493 new_size);
494 if (!compression && !encryption)
495 ret = btrfs_truncate_item(trans, root, path,
496 new_size, 0);
497 BUG_ON(ret);
498 }
499 /* create bookend, splitting the extent in two */
500 if (bookend && found_extent) {
501 struct btrfs_key ins;
502 ins.objectid = inode->i_ino;
503 ins.offset = end;
504 btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
505
506 btrfs_release_path(root, path);
507 path->leave_spinning = 1;
508 ret = btrfs_insert_empty_item(trans, root, path, &ins,
509 sizeof(*extent));
510 BUG_ON(ret);
511
512 leaf = path->nodes[0];
513 extent = btrfs_item_ptr(leaf, path->slots[0],
514 struct btrfs_file_extent_item);
515 write_extent_buffer(leaf, &old,
516 (unsigned long)extent, sizeof(old));
517
518 btrfs_set_file_extent_compression(leaf, extent,
519 compression);
520 btrfs_set_file_extent_encryption(leaf, extent,
521 encryption);
522 btrfs_set_file_extent_other_encoding(leaf, extent,
523 other_encoding);
524 btrfs_set_file_extent_offset(leaf, extent,
525 le64_to_cpu(old.offset) + end - key.offset);
526 WARN_ON(le64_to_cpu(old.num_bytes) <
527 (extent_end - end));
528 btrfs_set_file_extent_num_bytes(leaf, extent,
529 extent_end - end);
530
531 /*
532 * set the ram bytes to the size of the full extent
533 * before splitting. This is a worst case flag,
534 * but its the best we can do because we don't know
535 * how splitting affects compression
536 */
537 btrfs_set_file_extent_ram_bytes(leaf, extent,
538 ram_bytes);
539 btrfs_set_file_extent_type(leaf, extent, found_type);
540
541 btrfs_unlock_up_safe(path, 1);
542 btrfs_mark_buffer_dirty(path->nodes[0]);
543 btrfs_set_lock_blocking(path->nodes[0]);
544
545 path->leave_spinning = 0;
546 btrfs_release_path(root, path);
547 if (disk_bytenr != 0)
548 inode_add_bytes(inode, extent_end - end);
549 }
550
551 if (found_extent && !keep) {
552 u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
553
554 if (old_disk_bytenr != 0) {
555 inode_sub_bytes(inode,
556 le64_to_cpu(old.num_bytes));
557 ret = btrfs_free_extent(trans, root,
558 old_disk_bytenr,
559 le64_to_cpu(old.disk_num_bytes),
560 0, root->root_key.objectid,
561 key.objectid, key.offset -
562 le64_to_cpu(old.offset));
563 BUG_ON(ret);
564 *hint_byte = old_disk_bytenr;
565 }
566 }
567
568 if (search_start >= end) {
569 ret = 0;
570 goto out;
571 }
572 }
573 out:
574 btrfs_free_path(path);
575 if (locked_end > orig_locked_end) {
576 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
577 locked_end - 1, GFP_NOFS);
578 }
579 return ret;
580 }
581
582 static int extent_mergeable(struct extent_buffer *leaf, int slot,
583 u64 objectid, u64 bytenr, u64 *start, u64 *end)
584 {
585 struct btrfs_file_extent_item *fi;
586 struct btrfs_key key;
587 u64 extent_end;
588
589 if (slot < 0 || slot >= btrfs_header_nritems(leaf))
590 return 0;
591
592 btrfs_item_key_to_cpu(leaf, &key, slot);
593 if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
594 return 0;
595
596 fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
597 if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
598 btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
599 btrfs_file_extent_compression(leaf, fi) ||
600 btrfs_file_extent_encryption(leaf, fi) ||
601 btrfs_file_extent_other_encoding(leaf, fi))
602 return 0;
603
604 extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
605 if ((*start && *start != key.offset) || (*end && *end != extent_end))
606 return 0;
607
608 *start = key.offset;
609 *end = extent_end;
610 return 1;
611 }
612
613 /*
614 * Mark extent in the range start - end as written.
615 *
616 * This changes extent type from 'pre-allocated' to 'regular'. If only
617 * part of extent is marked as written, the extent will be split into
618 * two or three.
619 */
620 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
621 struct btrfs_root *root,
622 struct inode *inode, u64 start, u64 end)
623 {
624 struct extent_buffer *leaf;
625 struct btrfs_path *path;
626 struct btrfs_file_extent_item *fi;
627 struct btrfs_key key;
628 u64 bytenr;
629 u64 num_bytes;
630 u64 extent_end;
631 u64 orig_offset;
632 u64 other_start;
633 u64 other_end;
634 u64 split = start;
635 u64 locked_end = end;
636 int extent_type;
637 int split_end = 1;
638 int ret;
639
640 btrfs_drop_extent_cache(inode, start, end - 1, 0);
641
642 path = btrfs_alloc_path();
643 BUG_ON(!path);
644 again:
645 key.objectid = inode->i_ino;
646 key.type = BTRFS_EXTENT_DATA_KEY;
647 if (split == start)
648 key.offset = split;
649 else
650 key.offset = split - 1;
651
652 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
653 if (ret > 0 && path->slots[0] > 0)
654 path->slots[0]--;
655
656 leaf = path->nodes[0];
657 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
658 BUG_ON(key.objectid != inode->i_ino ||
659 key.type != BTRFS_EXTENT_DATA_KEY);
660 fi = btrfs_item_ptr(leaf, path->slots[0],
661 struct btrfs_file_extent_item);
662 extent_type = btrfs_file_extent_type(leaf, fi);
663 BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
664 extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
665 BUG_ON(key.offset > start || extent_end < end);
666
667 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
668 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
669 orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
670
671 if (key.offset == start)
672 split = end;
673
674 if (key.offset == start && extent_end == end) {
675 int del_nr = 0;
676 int del_slot = 0;
677 other_start = end;
678 other_end = 0;
679 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
680 bytenr, &other_start, &other_end)) {
681 extent_end = other_end;
682 del_slot = path->slots[0] + 1;
683 del_nr++;
684 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
685 0, root->root_key.objectid,
686 inode->i_ino, orig_offset);
687 BUG_ON(ret);
688 }
689 other_start = 0;
690 other_end = start;
691 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
692 bytenr, &other_start, &other_end)) {
693 key.offset = other_start;
694 del_slot = path->slots[0];
695 del_nr++;
696 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
697 0, root->root_key.objectid,
698 inode->i_ino, orig_offset);
699 BUG_ON(ret);
700 }
701 split_end = 0;
702 if (del_nr == 0) {
703 btrfs_set_file_extent_type(leaf, fi,
704 BTRFS_FILE_EXTENT_REG);
705 goto done;
706 }
707
708 fi = btrfs_item_ptr(leaf, del_slot - 1,
709 struct btrfs_file_extent_item);
710 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
711 btrfs_set_file_extent_num_bytes(leaf, fi,
712 extent_end - key.offset);
713 btrfs_mark_buffer_dirty(leaf);
714
715 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
716 BUG_ON(ret);
717 goto release;
718 } else if (split == start) {
719 if (locked_end < extent_end) {
720 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
721 locked_end, extent_end - 1, GFP_NOFS);
722 if (!ret) {
723 btrfs_release_path(root, path);
724 lock_extent(&BTRFS_I(inode)->io_tree,
725 locked_end, extent_end - 1, GFP_NOFS);
726 locked_end = extent_end;
727 goto again;
728 }
729 locked_end = extent_end;
730 }
731 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
732 } else {
733 BUG_ON(key.offset != start);
734 key.offset = split;
735 btrfs_set_file_extent_offset(leaf, fi, key.offset -
736 orig_offset);
737 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
738 btrfs_set_item_key_safe(trans, root, path, &key);
739 extent_end = split;
740 }
741
742 if (extent_end == end) {
743 split_end = 0;
744 extent_type = BTRFS_FILE_EXTENT_REG;
745 }
746 if (extent_end == end && split == start) {
747 other_start = end;
748 other_end = 0;
749 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
750 bytenr, &other_start, &other_end)) {
751 path->slots[0]++;
752 fi = btrfs_item_ptr(leaf, path->slots[0],
753 struct btrfs_file_extent_item);
754 key.offset = split;
755 btrfs_set_item_key_safe(trans, root, path, &key);
756 btrfs_set_file_extent_offset(leaf, fi, key.offset -
757 orig_offset);
758 btrfs_set_file_extent_num_bytes(leaf, fi,
759 other_end - split);
760 goto done;
761 }
762 }
763 if (extent_end == end && split == end) {
764 other_start = 0;
765 other_end = start;
766 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
767 bytenr, &other_start, &other_end)) {
768 path->slots[0]--;
769 fi = btrfs_item_ptr(leaf, path->slots[0],
770 struct btrfs_file_extent_item);
771 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
772 other_start);
773 goto done;
774 }
775 }
776
777 btrfs_mark_buffer_dirty(leaf);
778
779 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
780 root->root_key.objectid,
781 inode->i_ino, orig_offset);
782 BUG_ON(ret);
783 btrfs_release_path(root, path);
784
785 key.offset = start;
786 ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
787 BUG_ON(ret);
788
789 leaf = path->nodes[0];
790 fi = btrfs_item_ptr(leaf, path->slots[0],
791 struct btrfs_file_extent_item);
792 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
793 btrfs_set_file_extent_type(leaf, fi, extent_type);
794 btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
795 btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
796 btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
797 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
798 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
799 btrfs_set_file_extent_compression(leaf, fi, 0);
800 btrfs_set_file_extent_encryption(leaf, fi, 0);
801 btrfs_set_file_extent_other_encoding(leaf, fi, 0);
802 done:
803 btrfs_mark_buffer_dirty(leaf);
804
805 release:
806 btrfs_release_path(root, path);
807 if (split_end && split == start) {
808 split = end;
809 goto again;
810 }
811 if (locked_end > end) {
812 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
813 GFP_NOFS);
814 }
815 btrfs_free_path(path);
816 return 0;
817 }
818
819 /*
820 * this gets pages into the page cache and locks them down, it also properly
821 * waits for data=ordered extents to finish before allowing the pages to be
822 * modified.
823 */
824 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
825 struct page **pages, size_t num_pages,
826 loff_t pos, unsigned long first_index,
827 unsigned long last_index, size_t write_bytes)
828 {
829 int i;
830 unsigned long index = pos >> PAGE_CACHE_SHIFT;
831 struct inode *inode = fdentry(file)->d_inode;
832 int err = 0;
833 u64 start_pos;
834 u64 last_pos;
835
836 start_pos = pos & ~((u64)root->sectorsize - 1);
837 last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
838
839 if (start_pos > inode->i_size) {
840 err = btrfs_cont_expand(inode, start_pos);
841 if (err)
842 return err;
843 }
844
845 memset(pages, 0, num_pages * sizeof(struct page *));
846 again:
847 for (i = 0; i < num_pages; i++) {
848 pages[i] = grab_cache_page(inode->i_mapping, index + i);
849 if (!pages[i]) {
850 err = -ENOMEM;
851 BUG_ON(1);
852 }
853 wait_on_page_writeback(pages[i]);
854 }
855 if (start_pos < inode->i_size) {
856 struct btrfs_ordered_extent *ordered;
857 lock_extent(&BTRFS_I(inode)->io_tree,
858 start_pos, last_pos - 1, GFP_NOFS);
859 ordered = btrfs_lookup_first_ordered_extent(inode,
860 last_pos - 1);
861 if (ordered &&
862 ordered->file_offset + ordered->len > start_pos &&
863 ordered->file_offset < last_pos) {
864 btrfs_put_ordered_extent(ordered);
865 unlock_extent(&BTRFS_I(inode)->io_tree,
866 start_pos, last_pos - 1, GFP_NOFS);
867 for (i = 0; i < num_pages; i++) {
868 unlock_page(pages[i]);
869 page_cache_release(pages[i]);
870 }
871 btrfs_wait_ordered_range(inode, start_pos,
872 last_pos - start_pos);
873 goto again;
874 }
875 if (ordered)
876 btrfs_put_ordered_extent(ordered);
877
878 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
879 last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
880 GFP_NOFS);
881 unlock_extent(&BTRFS_I(inode)->io_tree,
882 start_pos, last_pos - 1, GFP_NOFS);
883 }
884 for (i = 0; i < num_pages; i++) {
885 clear_page_dirty_for_io(pages[i]);
886 set_page_extent_mapped(pages[i]);
887 WARN_ON(!PageLocked(pages[i]));
888 }
889 return 0;
890 }
891
892 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
893 size_t count, loff_t *ppos)
894 {
895 loff_t pos;
896 loff_t start_pos;
897 ssize_t num_written = 0;
898 ssize_t err = 0;
899 int ret = 0;
900 struct inode *inode = fdentry(file)->d_inode;
901 struct btrfs_root *root = BTRFS_I(inode)->root;
902 struct page **pages = NULL;
903 int nrptrs;
904 struct page *pinned[2];
905 unsigned long first_index;
906 unsigned long last_index;
907 int will_write;
908
909 will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
910 (file->f_flags & O_DIRECT));
911
912 nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
913 PAGE_CACHE_SIZE / (sizeof(struct page *)));
914 pinned[0] = NULL;
915 pinned[1] = NULL;
916
917 pos = *ppos;
918 start_pos = pos;
919
920 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
921 current->backing_dev_info = inode->i_mapping->backing_dev_info;
922 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
923 if (err)
924 goto out_nolock;
925 if (count == 0)
926 goto out_nolock;
927
928 err = file_remove_suid(file);
929 if (err)
930 goto out_nolock;
931 file_update_time(file);
932
933 pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
934
935 mutex_lock(&inode->i_mutex);
936 BTRFS_I(inode)->sequence++;
937 first_index = pos >> PAGE_CACHE_SHIFT;
938 last_index = (pos + count) >> PAGE_CACHE_SHIFT;
939
940 /*
941 * there are lots of better ways to do this, but this code
942 * makes sure the first and last page in the file range are
943 * up to date and ready for cow
944 */
945 if ((pos & (PAGE_CACHE_SIZE - 1))) {
946 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
947 if (!PageUptodate(pinned[0])) {
948 ret = btrfs_readpage(NULL, pinned[0]);
949 BUG_ON(ret);
950 wait_on_page_locked(pinned[0]);
951 } else {
952 unlock_page(pinned[0]);
953 }
954 }
955 if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
956 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
957 if (!PageUptodate(pinned[1])) {
958 ret = btrfs_readpage(NULL, pinned[1]);
959 BUG_ON(ret);
960 wait_on_page_locked(pinned[1]);
961 } else {
962 unlock_page(pinned[1]);
963 }
964 }
965
966 while (count > 0) {
967 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
968 size_t write_bytes = min(count, nrptrs *
969 (size_t)PAGE_CACHE_SIZE -
970 offset);
971 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
972 PAGE_CACHE_SHIFT;
973
974 WARN_ON(num_pages > nrptrs);
975 memset(pages, 0, sizeof(struct page *) * nrptrs);
976
977 ret = btrfs_check_data_free_space(root, inode, write_bytes);
978 if (ret)
979 goto out;
980
981 ret = prepare_pages(root, file, pages, num_pages,
982 pos, first_index, last_index,
983 write_bytes);
984 if (ret) {
985 btrfs_free_reserved_data_space(root, inode,
986 write_bytes);
987 goto out;
988 }
989
990 ret = btrfs_copy_from_user(pos, num_pages,
991 write_bytes, pages, buf);
992 if (ret) {
993 btrfs_free_reserved_data_space(root, inode,
994 write_bytes);
995 btrfs_drop_pages(pages, num_pages);
996 goto out;
997 }
998
999 ret = dirty_and_release_pages(NULL, root, file, pages,
1000 num_pages, pos, write_bytes);
1001 btrfs_drop_pages(pages, num_pages);
1002 if (ret) {
1003 btrfs_free_reserved_data_space(root, inode,
1004 write_bytes);
1005 goto out;
1006 }
1007
1008 if (will_write) {
1009 btrfs_fdatawrite_range(inode->i_mapping, pos,
1010 pos + write_bytes - 1,
1011 WB_SYNC_ALL);
1012 } else {
1013 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1014 num_pages);
1015 if (num_pages <
1016 (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1017 btrfs_btree_balance_dirty(root, 1);
1018 btrfs_throttle(root);
1019 }
1020
1021 buf += write_bytes;
1022 count -= write_bytes;
1023 pos += write_bytes;
1024 num_written += write_bytes;
1025
1026 cond_resched();
1027 }
1028 out:
1029 mutex_unlock(&inode->i_mutex);
1030 if (ret)
1031 err = ret;
1032
1033 out_nolock:
1034 kfree(pages);
1035 if (pinned[0])
1036 page_cache_release(pinned[0]);
1037 if (pinned[1])
1038 page_cache_release(pinned[1]);
1039 *ppos = pos;
1040
1041 /*
1042 * we want to make sure fsync finds this change
1043 * but we haven't joined a transaction running right now.
1044 *
1045 * Later on, someone is sure to update the inode and get the
1046 * real transid recorded.
1047 *
1048 * We set last_trans now to the fs_info generation + 1,
1049 * this will either be one more than the running transaction
1050 * or the generation used for the next transaction if there isn't
1051 * one running right now.
1052 */
1053 BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1054
1055 if (num_written > 0 && will_write) {
1056 struct btrfs_trans_handle *trans;
1057
1058 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1059 if (err)
1060 num_written = err;
1061
1062 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1063 trans = btrfs_start_transaction(root, 1);
1064 ret = btrfs_log_dentry_safe(trans, root,
1065 file->f_dentry);
1066 if (ret == 0) {
1067 ret = btrfs_sync_log(trans, root);
1068 if (ret == 0)
1069 btrfs_end_transaction(trans, root);
1070 else
1071 btrfs_commit_transaction(trans, root);
1072 } else {
1073 btrfs_commit_transaction(trans, root);
1074 }
1075 }
1076 if (file->f_flags & O_DIRECT) {
1077 invalidate_mapping_pages(inode->i_mapping,
1078 start_pos >> PAGE_CACHE_SHIFT,
1079 (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1080 }
1081 }
1082 current->backing_dev_info = NULL;
1083 return num_written ? num_written : err;
1084 }
1085
1086 int btrfs_release_file(struct inode *inode, struct file *filp)
1087 {
1088 /*
1089 * ordered_data_close is set by settattr when we are about to truncate
1090 * a file from a non-zero size to a zero size. This tries to
1091 * flush down new bytes that may have been written if the
1092 * application were using truncate to replace a file in place.
1093 */
1094 if (BTRFS_I(inode)->ordered_data_close) {
1095 BTRFS_I(inode)->ordered_data_close = 0;
1096 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1097 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1098 filemap_flush(inode->i_mapping);
1099 }
1100 if (filp->private_data)
1101 btrfs_ioctl_trans_end(filp);
1102 return 0;
1103 }
1104
1105 /*
1106 * fsync call for both files and directories. This logs the inode into
1107 * the tree log instead of forcing full commits whenever possible.
1108 *
1109 * It needs to call filemap_fdatawait so that all ordered extent updates are
1110 * in the metadata btree are up to date for copying to the log.
1111 *
1112 * It drops the inode mutex before doing the tree log commit. This is an
1113 * important optimization for directories because holding the mutex prevents
1114 * new operations on the dir while we write to disk.
1115 */
1116 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1117 {
1118 struct inode *inode = dentry->d_inode;
1119 struct btrfs_root *root = BTRFS_I(inode)->root;
1120 int ret = 0;
1121 struct btrfs_trans_handle *trans;
1122
1123 /*
1124 * check the transaction that last modified this inode
1125 * and see if its already been committed
1126 */
1127 if (!BTRFS_I(inode)->last_trans)
1128 goto out;
1129
1130 mutex_lock(&root->fs_info->trans_mutex);
1131 if (BTRFS_I(inode)->last_trans <=
1132 root->fs_info->last_trans_committed) {
1133 BTRFS_I(inode)->last_trans = 0;
1134 mutex_unlock(&root->fs_info->trans_mutex);
1135 goto out;
1136 }
1137 mutex_unlock(&root->fs_info->trans_mutex);
1138
1139 root->log_batch++;
1140 filemap_fdatawrite(inode->i_mapping);
1141 btrfs_wait_ordered_range(inode, 0, (u64)-1);
1142 root->log_batch++;
1143
1144 if (datasync && !(inode->i_state & I_DIRTY_PAGES))
1145 goto out;
1146 /*
1147 * ok we haven't committed the transaction yet, lets do a commit
1148 */
1149 if (file && file->private_data)
1150 btrfs_ioctl_trans_end(file);
1151
1152 trans = btrfs_start_transaction(root, 1);
1153 if (!trans) {
1154 ret = -ENOMEM;
1155 goto out;
1156 }
1157
1158 ret = btrfs_log_dentry_safe(trans, root, dentry);
1159 if (ret < 0)
1160 goto out;
1161
1162 /* we've logged all the items and now have a consistent
1163 * version of the file in the log. It is possible that
1164 * someone will come in and modify the file, but that's
1165 * fine because the log is consistent on disk, and we
1166 * have references to all of the file's extents
1167 *
1168 * It is possible that someone will come in and log the
1169 * file again, but that will end up using the synchronization
1170 * inside btrfs_sync_log to keep things safe.
1171 */
1172 mutex_unlock(&dentry->d_inode->i_mutex);
1173
1174 if (ret > 0) {
1175 ret = btrfs_commit_transaction(trans, root);
1176 } else {
1177 ret = btrfs_sync_log(trans, root);
1178 if (ret == 0)
1179 ret = btrfs_end_transaction(trans, root);
1180 else
1181 ret = btrfs_commit_transaction(trans, root);
1182 }
1183 mutex_lock(&dentry->d_inode->i_mutex);
1184 out:
1185 return ret > 0 ? EIO : ret;
1186 }
1187
1188 static struct vm_operations_struct btrfs_file_vm_ops = {
1189 .fault = filemap_fault,
1190 .page_mkwrite = btrfs_page_mkwrite,
1191 };
1192
1193 static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma)
1194 {
1195 vma->vm_ops = &btrfs_file_vm_ops;
1196 file_accessed(filp);
1197 return 0;
1198 }
1199
1200 struct file_operations btrfs_file_operations = {
1201 .llseek = generic_file_llseek,
1202 .read = do_sync_read,
1203 .aio_read = generic_file_aio_read,
1204 .splice_read = generic_file_splice_read,
1205 .write = btrfs_file_write,
1206 .mmap = btrfs_file_mmap,
1207 .open = generic_file_open,
1208 .release = btrfs_release_file,
1209 .fsync = btrfs_sync_file,
1210 .unlocked_ioctl = btrfs_ioctl,
1211 #ifdef CONFIG_COMPAT
1212 .compat_ioctl = btrfs_ioctl,
1213 #endif
1214 };
Linux kernel - Deliverables
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