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Btrfs: switch extent_map to a rw lock
[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 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
117 u64 hint_byte;
118 u64 num_bytes;
119 u64 start_pos;
120 u64 end_of_last_block;
121 u64 end_pos = pos + write_bytes;
122 loff_t isize = i_size_read(inode);
123
124 start_pos = pos & ~((u64)root->sectorsize - 1);
125 num_bytes = (write_bytes + pos - start_pos +
126 root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
127
128 end_of_last_block = start_pos + num_bytes - 1;
129
130 lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
131 trans = btrfs_join_transaction(root, 1);
132 if (!trans) {
133 err = -ENOMEM;
134 goto out_unlock;
135 }
136 btrfs_set_trans_block_group(trans, inode);
137 hint_byte = 0;
138
139 /* check for reserved extents on each page, we don't want
140 * to reset the delalloc bit on things that already have
141 * extents reserved.
142 */
143 btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
144 for (i = 0; i < num_pages; i++) {
145 struct page *p = pages[i];
146 SetPageUptodate(p);
147 ClearPageChecked(p);
148 set_page_dirty(p);
149 }
150 if (end_pos > isize) {
151 i_size_write(inode, end_pos);
152 /* we've only changed i_size in ram, and we haven't updated
153 * the disk i_size. There is no need to log the inode
154 * at this time.
155 */
156 }
157 err = btrfs_end_transaction(trans, root);
158 out_unlock:
159 unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
160 return err;
161 }
162
163 /*
164 * this drops all the extents in the cache that intersect the range
165 * [start, end]. Existing extents are split as required.
166 */
167 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
168 int skip_pinned)
169 {
170 struct extent_map *em;
171 struct extent_map *split = NULL;
172 struct extent_map *split2 = NULL;
173 struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
174 u64 len = end - start + 1;
175 int ret;
176 int testend = 1;
177 unsigned long flags;
178 int compressed = 0;
179
180 WARN_ON(end < start);
181 if (end == (u64)-1) {
182 len = (u64)-1;
183 testend = 0;
184 }
185 while (1) {
186 if (!split)
187 split = alloc_extent_map(GFP_NOFS);
188 if (!split2)
189 split2 = alloc_extent_map(GFP_NOFS);
190
191 write_lock(&em_tree->lock);
192 em = lookup_extent_mapping(em_tree, start, len);
193 if (!em) {
194 write_unlock(&em_tree->lock);
195 break;
196 }
197 flags = em->flags;
198 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
199 write_unlock(&em_tree->lock);
200 if (em->start <= start &&
201 (!testend || em->start + em->len >= start + len)) {
202 free_extent_map(em);
203 break;
204 }
205 if (start < em->start) {
206 len = em->start - start;
207 } else {
208 len = start + len - (em->start + em->len);
209 start = em->start + em->len;
210 }
211 free_extent_map(em);
212 continue;
213 }
214 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
215 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
216 remove_extent_mapping(em_tree, em);
217
218 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
219 em->start < start) {
220 split->start = em->start;
221 split->len = start - em->start;
222 split->orig_start = em->orig_start;
223 split->block_start = em->block_start;
224
225 if (compressed)
226 split->block_len = em->block_len;
227 else
228 split->block_len = split->len;
229
230 split->bdev = em->bdev;
231 split->flags = flags;
232 ret = add_extent_mapping(em_tree, split);
233 BUG_ON(ret);
234 free_extent_map(split);
235 split = split2;
236 split2 = NULL;
237 }
238 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
239 testend && em->start + em->len > start + len) {
240 u64 diff = start + len - em->start;
241
242 split->start = start + len;
243 split->len = em->start + em->len - (start + len);
244 split->bdev = em->bdev;
245 split->flags = flags;
246
247 if (compressed) {
248 split->block_len = em->block_len;
249 split->block_start = em->block_start;
250 split->orig_start = em->orig_start;
251 } else {
252 split->block_len = split->len;
253 split->block_start = em->block_start + diff;
254 split->orig_start = split->start;
255 }
256
257 ret = add_extent_mapping(em_tree, split);
258 BUG_ON(ret);
259 free_extent_map(split);
260 split = NULL;
261 }
262 write_unlock(&em_tree->lock);
263
264 /* once for us */
265 free_extent_map(em);
266 /* once for the tree*/
267 free_extent_map(em);
268 }
269 if (split)
270 free_extent_map(split);
271 if (split2)
272 free_extent_map(split2);
273 return 0;
274 }
275
276 /*
277 * this is very complex, but the basic idea is to drop all extents
278 * in the range start - end. hint_block is filled in with a block number
279 * that would be a good hint to the block allocator for this file.
280 *
281 * If an extent intersects the range but is not entirely inside the range
282 * it is either truncated or split. Anything entirely inside the range
283 * is deleted from the tree.
284 *
285 * inline_limit is used to tell this code which offsets in the file to keep
286 * if they contain inline extents.
287 */
288 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
289 struct btrfs_root *root, struct inode *inode,
290 u64 start, u64 end, u64 locked_end,
291 u64 inline_limit, u64 *hint_byte)
292 {
293 u64 extent_end = 0;
294 u64 search_start = start;
295 u64 ram_bytes = 0;
296 u64 disk_bytenr = 0;
297 u64 orig_locked_end = locked_end;
298 u8 compression;
299 u8 encryption;
300 u16 other_encoding = 0;
301 struct extent_buffer *leaf;
302 struct btrfs_file_extent_item *extent;
303 struct btrfs_path *path;
304 struct btrfs_key key;
305 struct btrfs_file_extent_item old;
306 int keep;
307 int slot;
308 int bookend;
309 int found_type = 0;
310 int found_extent;
311 int found_inline;
312 int recow;
313 int ret;
314
315 inline_limit = 0;
316 btrfs_drop_extent_cache(inode, start, end - 1, 0);
317
318 path = btrfs_alloc_path();
319 if (!path)
320 return -ENOMEM;
321 while (1) {
322 recow = 0;
323 btrfs_release_path(root, path);
324 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
325 search_start, -1);
326 if (ret < 0)
327 goto out;
328 if (ret > 0) {
329 if (path->slots[0] == 0) {
330 ret = 0;
331 goto out;
332 }
333 path->slots[0]--;
334 }
335 next_slot:
336 keep = 0;
337 bookend = 0;
338 found_extent = 0;
339 found_inline = 0;
340 compression = 0;
341 encryption = 0;
342 extent = NULL;
343 leaf = path->nodes[0];
344 slot = path->slots[0];
345 ret = 0;
346 btrfs_item_key_to_cpu(leaf, &key, slot);
347 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
348 key.offset >= end) {
349 goto out;
350 }
351 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
352 key.objectid != inode->i_ino) {
353 goto out;
354 }
355 if (recow) {
356 search_start = max(key.offset, start);
357 continue;
358 }
359 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
360 extent = btrfs_item_ptr(leaf, slot,
361 struct btrfs_file_extent_item);
362 found_type = btrfs_file_extent_type(leaf, extent);
363 compression = btrfs_file_extent_compression(leaf,
364 extent);
365 encryption = btrfs_file_extent_encryption(leaf,
366 extent);
367 other_encoding = btrfs_file_extent_other_encoding(leaf,
368 extent);
369 if (found_type == BTRFS_FILE_EXTENT_REG ||
370 found_type == BTRFS_FILE_EXTENT_PREALLOC) {
371 extent_end =
372 btrfs_file_extent_disk_bytenr(leaf,
373 extent);
374 if (extent_end)
375 *hint_byte = extent_end;
376
377 extent_end = key.offset +
378 btrfs_file_extent_num_bytes(leaf, extent);
379 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
380 extent);
381 found_extent = 1;
382 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
383 found_inline = 1;
384 extent_end = key.offset +
385 btrfs_file_extent_inline_len(leaf, extent);
386 }
387 } else {
388 extent_end = search_start;
389 }
390
391 /* we found nothing we can drop */
392 if ((!found_extent && !found_inline) ||
393 search_start >= extent_end) {
394 int nextret;
395 u32 nritems;
396 nritems = btrfs_header_nritems(leaf);
397 if (slot >= nritems - 1) {
398 nextret = btrfs_next_leaf(root, path);
399 if (nextret)
400 goto out;
401 recow = 1;
402 } else {
403 path->slots[0]++;
404 }
405 goto next_slot;
406 }
407
408 if (end <= extent_end && start >= key.offset && found_inline)
409 *hint_byte = EXTENT_MAP_INLINE;
410
411 if (found_extent) {
412 read_extent_buffer(leaf, &old, (unsigned long)extent,
413 sizeof(old));
414 }
415
416 if (end < extent_end && end >= key.offset) {
417 bookend = 1;
418 if (found_inline && start <= key.offset)
419 keep = 1;
420 }
421
422 if (bookend && found_extent) {
423 if (locked_end < extent_end) {
424 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
425 locked_end, extent_end - 1,
426 GFP_NOFS);
427 if (!ret) {
428 btrfs_release_path(root, path);
429 lock_extent(&BTRFS_I(inode)->io_tree,
430 locked_end, extent_end - 1,
431 GFP_NOFS);
432 locked_end = extent_end;
433 continue;
434 }
435 locked_end = extent_end;
436 }
437 disk_bytenr = le64_to_cpu(old.disk_bytenr);
438 if (disk_bytenr != 0) {
439 ret = btrfs_inc_extent_ref(trans, root,
440 disk_bytenr,
441 le64_to_cpu(old.disk_num_bytes), 0,
442 root->root_key.objectid,
443 key.objectid, key.offset -
444 le64_to_cpu(old.offset));
445 BUG_ON(ret);
446 }
447 }
448
449 if (found_inline) {
450 u64 mask = root->sectorsize - 1;
451 search_start = (extent_end + mask) & ~mask;
452 } else
453 search_start = extent_end;
454
455 /* truncate existing extent */
456 if (start > key.offset) {
457 u64 new_num;
458 u64 old_num;
459 keep = 1;
460 WARN_ON(start & (root->sectorsize - 1));
461 if (found_extent) {
462 new_num = start - key.offset;
463 old_num = btrfs_file_extent_num_bytes(leaf,
464 extent);
465 *hint_byte =
466 btrfs_file_extent_disk_bytenr(leaf,
467 extent);
468 if (btrfs_file_extent_disk_bytenr(leaf,
469 extent)) {
470 inode_sub_bytes(inode, old_num -
471 new_num);
472 }
473 btrfs_set_file_extent_num_bytes(leaf,
474 extent, new_num);
475 btrfs_mark_buffer_dirty(leaf);
476 } else if (key.offset < inline_limit &&
477 (end > extent_end) &&
478 (inline_limit < extent_end)) {
479 u32 new_size;
480 new_size = btrfs_file_extent_calc_inline_size(
481 inline_limit - key.offset);
482 inode_sub_bytes(inode, extent_end -
483 inline_limit);
484 btrfs_set_file_extent_ram_bytes(leaf, extent,
485 new_size);
486 if (!compression && !encryption) {
487 btrfs_truncate_item(trans, root, path,
488 new_size, 1);
489 }
490 }
491 }
492 /* delete the entire extent */
493 if (!keep) {
494 if (found_inline)
495 inode_sub_bytes(inode, extent_end -
496 key.offset);
497 ret = btrfs_del_item(trans, root, path);
498 /* TODO update progress marker and return */
499 BUG_ON(ret);
500 extent = NULL;
501 btrfs_release_path(root, path);
502 /* the extent will be freed later */
503 }
504 if (bookend && found_inline && start <= key.offset) {
505 u32 new_size;
506 new_size = btrfs_file_extent_calc_inline_size(
507 extent_end - end);
508 inode_sub_bytes(inode, end - key.offset);
509 btrfs_set_file_extent_ram_bytes(leaf, extent,
510 new_size);
511 if (!compression && !encryption)
512 ret = btrfs_truncate_item(trans, root, path,
513 new_size, 0);
514 BUG_ON(ret);
515 }
516 /* create bookend, splitting the extent in two */
517 if (bookend && found_extent) {
518 struct btrfs_key ins;
519 ins.objectid = inode->i_ino;
520 ins.offset = end;
521 btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
522
523 btrfs_release_path(root, path);
524 path->leave_spinning = 1;
525 ret = btrfs_insert_empty_item(trans, root, path, &ins,
526 sizeof(*extent));
527 BUG_ON(ret);
528
529 leaf = path->nodes[0];
530 extent = btrfs_item_ptr(leaf, path->slots[0],
531 struct btrfs_file_extent_item);
532 write_extent_buffer(leaf, &old,
533 (unsigned long)extent, sizeof(old));
534
535 btrfs_set_file_extent_compression(leaf, extent,
536 compression);
537 btrfs_set_file_extent_encryption(leaf, extent,
538 encryption);
539 btrfs_set_file_extent_other_encoding(leaf, extent,
540 other_encoding);
541 btrfs_set_file_extent_offset(leaf, extent,
542 le64_to_cpu(old.offset) + end - key.offset);
543 WARN_ON(le64_to_cpu(old.num_bytes) <
544 (extent_end - end));
545 btrfs_set_file_extent_num_bytes(leaf, extent,
546 extent_end - end);
547
548 /*
549 * set the ram bytes to the size of the full extent
550 * before splitting. This is a worst case flag,
551 * but its the best we can do because we don't know
552 * how splitting affects compression
553 */
554 btrfs_set_file_extent_ram_bytes(leaf, extent,
555 ram_bytes);
556 btrfs_set_file_extent_type(leaf, extent, found_type);
557
558 btrfs_unlock_up_safe(path, 1);
559 btrfs_mark_buffer_dirty(path->nodes[0]);
560 btrfs_set_lock_blocking(path->nodes[0]);
561
562 path->leave_spinning = 0;
563 btrfs_release_path(root, path);
564 if (disk_bytenr != 0)
565 inode_add_bytes(inode, extent_end - end);
566 }
567
568 if (found_extent && !keep) {
569 u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
570
571 if (old_disk_bytenr != 0) {
572 inode_sub_bytes(inode,
573 le64_to_cpu(old.num_bytes));
574 ret = btrfs_free_extent(trans, root,
575 old_disk_bytenr,
576 le64_to_cpu(old.disk_num_bytes),
577 0, root->root_key.objectid,
578 key.objectid, key.offset -
579 le64_to_cpu(old.offset));
580 BUG_ON(ret);
581 *hint_byte = old_disk_bytenr;
582 }
583 }
584
585 if (search_start >= end) {
586 ret = 0;
587 goto out;
588 }
589 }
590 out:
591 btrfs_free_path(path);
592 if (locked_end > orig_locked_end) {
593 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
594 locked_end - 1, GFP_NOFS);
595 }
596 return ret;
597 }
598
599 static int extent_mergeable(struct extent_buffer *leaf, int slot,
600 u64 objectid, u64 bytenr, u64 *start, u64 *end)
601 {
602 struct btrfs_file_extent_item *fi;
603 struct btrfs_key key;
604 u64 extent_end;
605
606 if (slot < 0 || slot >= btrfs_header_nritems(leaf))
607 return 0;
608
609 btrfs_item_key_to_cpu(leaf, &key, slot);
610 if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
611 return 0;
612
613 fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
614 if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
615 btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
616 btrfs_file_extent_compression(leaf, fi) ||
617 btrfs_file_extent_encryption(leaf, fi) ||
618 btrfs_file_extent_other_encoding(leaf, fi))
619 return 0;
620
621 extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
622 if ((*start && *start != key.offset) || (*end && *end != extent_end))
623 return 0;
624
625 *start = key.offset;
626 *end = extent_end;
627 return 1;
628 }
629
630 /*
631 * Mark extent in the range start - end as written.
632 *
633 * This changes extent type from 'pre-allocated' to 'regular'. If only
634 * part of extent is marked as written, the extent will be split into
635 * two or three.
636 */
637 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
638 struct btrfs_root *root,
639 struct inode *inode, u64 start, u64 end)
640 {
641 struct extent_buffer *leaf;
642 struct btrfs_path *path;
643 struct btrfs_file_extent_item *fi;
644 struct btrfs_key key;
645 u64 bytenr;
646 u64 num_bytes;
647 u64 extent_end;
648 u64 orig_offset;
649 u64 other_start;
650 u64 other_end;
651 u64 split = start;
652 u64 locked_end = end;
653 int extent_type;
654 int split_end = 1;
655 int ret;
656
657 btrfs_drop_extent_cache(inode, start, end - 1, 0);
658
659 path = btrfs_alloc_path();
660 BUG_ON(!path);
661 again:
662 key.objectid = inode->i_ino;
663 key.type = BTRFS_EXTENT_DATA_KEY;
664 if (split == start)
665 key.offset = split;
666 else
667 key.offset = split - 1;
668
669 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
670 if (ret > 0 && path->slots[0] > 0)
671 path->slots[0]--;
672
673 leaf = path->nodes[0];
674 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
675 BUG_ON(key.objectid != inode->i_ino ||
676 key.type != BTRFS_EXTENT_DATA_KEY);
677 fi = btrfs_item_ptr(leaf, path->slots[0],
678 struct btrfs_file_extent_item);
679 extent_type = btrfs_file_extent_type(leaf, fi);
680 BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
681 extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
682 BUG_ON(key.offset > start || extent_end < end);
683
684 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
685 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
686 orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
687
688 if (key.offset == start)
689 split = end;
690
691 if (key.offset == start && extent_end == end) {
692 int del_nr = 0;
693 int del_slot = 0;
694 other_start = end;
695 other_end = 0;
696 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
697 bytenr, &other_start, &other_end)) {
698 extent_end = other_end;
699 del_slot = path->slots[0] + 1;
700 del_nr++;
701 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
702 0, root->root_key.objectid,
703 inode->i_ino, orig_offset);
704 BUG_ON(ret);
705 }
706 other_start = 0;
707 other_end = start;
708 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
709 bytenr, &other_start, &other_end)) {
710 key.offset = other_start;
711 del_slot = path->slots[0];
712 del_nr++;
713 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
714 0, root->root_key.objectid,
715 inode->i_ino, orig_offset);
716 BUG_ON(ret);
717 }
718 split_end = 0;
719 if (del_nr == 0) {
720 btrfs_set_file_extent_type(leaf, fi,
721 BTRFS_FILE_EXTENT_REG);
722 goto done;
723 }
724
725 fi = btrfs_item_ptr(leaf, del_slot - 1,
726 struct btrfs_file_extent_item);
727 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
728 btrfs_set_file_extent_num_bytes(leaf, fi,
729 extent_end - key.offset);
730 btrfs_mark_buffer_dirty(leaf);
731
732 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
733 BUG_ON(ret);
734 goto release;
735 } else if (split == start) {
736 if (locked_end < extent_end) {
737 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
738 locked_end, extent_end - 1, GFP_NOFS);
739 if (!ret) {
740 btrfs_release_path(root, path);
741 lock_extent(&BTRFS_I(inode)->io_tree,
742 locked_end, extent_end - 1, GFP_NOFS);
743 locked_end = extent_end;
744 goto again;
745 }
746 locked_end = extent_end;
747 }
748 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
749 } else {
750 BUG_ON(key.offset != start);
751 key.offset = split;
752 btrfs_set_file_extent_offset(leaf, fi, key.offset -
753 orig_offset);
754 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
755 btrfs_set_item_key_safe(trans, root, path, &key);
756 extent_end = split;
757 }
758
759 if (extent_end == end) {
760 split_end = 0;
761 extent_type = BTRFS_FILE_EXTENT_REG;
762 }
763 if (extent_end == end && split == start) {
764 other_start = end;
765 other_end = 0;
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 key.offset = split;
772 btrfs_set_item_key_safe(trans, root, path, &key);
773 btrfs_set_file_extent_offset(leaf, fi, key.offset -
774 orig_offset);
775 btrfs_set_file_extent_num_bytes(leaf, fi,
776 other_end - split);
777 goto done;
778 }
779 }
780 if (extent_end == end && split == end) {
781 other_start = 0;
782 other_end = start;
783 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
784 bytenr, &other_start, &other_end)) {
785 path->slots[0]--;
786 fi = btrfs_item_ptr(leaf, path->slots[0],
787 struct btrfs_file_extent_item);
788 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
789 other_start);
790 goto done;
791 }
792 }
793
794 btrfs_mark_buffer_dirty(leaf);
795
796 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
797 root->root_key.objectid,
798 inode->i_ino, orig_offset);
799 BUG_ON(ret);
800 btrfs_release_path(root, path);
801
802 key.offset = start;
803 ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
804 BUG_ON(ret);
805
806 leaf = path->nodes[0];
807 fi = btrfs_item_ptr(leaf, path->slots[0],
808 struct btrfs_file_extent_item);
809 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
810 btrfs_set_file_extent_type(leaf, fi, extent_type);
811 btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
812 btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
813 btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
814 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
815 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
816 btrfs_set_file_extent_compression(leaf, fi, 0);
817 btrfs_set_file_extent_encryption(leaf, fi, 0);
818 btrfs_set_file_extent_other_encoding(leaf, fi, 0);
819 done:
820 btrfs_mark_buffer_dirty(leaf);
821
822 release:
823 btrfs_release_path(root, path);
824 if (split_end && split == start) {
825 split = end;
826 goto again;
827 }
828 if (locked_end > end) {
829 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
830 GFP_NOFS);
831 }
832 btrfs_free_path(path);
833 return 0;
834 }
835
836 /*
837 * this gets pages into the page cache and locks them down, it also properly
838 * waits for data=ordered extents to finish before allowing the pages to be
839 * modified.
840 */
841 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
842 struct page **pages, size_t num_pages,
843 loff_t pos, unsigned long first_index,
844 unsigned long last_index, size_t write_bytes)
845 {
846 int i;
847 unsigned long index = pos >> PAGE_CACHE_SHIFT;
848 struct inode *inode = fdentry(file)->d_inode;
849 int err = 0;
850 u64 start_pos;
851 u64 last_pos;
852
853 start_pos = pos & ~((u64)root->sectorsize - 1);
854 last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
855
856 if (start_pos > inode->i_size) {
857 err = btrfs_cont_expand(inode, start_pos);
858 if (err)
859 return err;
860 }
861
862 memset(pages, 0, num_pages * sizeof(struct page *));
863 again:
864 for (i = 0; i < num_pages; i++) {
865 pages[i] = grab_cache_page(inode->i_mapping, index + i);
866 if (!pages[i]) {
867 err = -ENOMEM;
868 BUG_ON(1);
869 }
870 wait_on_page_writeback(pages[i]);
871 }
872 if (start_pos < inode->i_size) {
873 struct btrfs_ordered_extent *ordered;
874 lock_extent(&BTRFS_I(inode)->io_tree,
875 start_pos, last_pos - 1, GFP_NOFS);
876 ordered = btrfs_lookup_first_ordered_extent(inode,
877 last_pos - 1);
878 if (ordered &&
879 ordered->file_offset + ordered->len > start_pos &&
880 ordered->file_offset < last_pos) {
881 btrfs_put_ordered_extent(ordered);
882 unlock_extent(&BTRFS_I(inode)->io_tree,
883 start_pos, last_pos - 1, GFP_NOFS);
884 for (i = 0; i < num_pages; i++) {
885 unlock_page(pages[i]);
886 page_cache_release(pages[i]);
887 }
888 btrfs_wait_ordered_range(inode, start_pos,
889 last_pos - start_pos);
890 goto again;
891 }
892 if (ordered)
893 btrfs_put_ordered_extent(ordered);
894
895 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
896 last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
897 GFP_NOFS);
898 unlock_extent(&BTRFS_I(inode)->io_tree,
899 start_pos, last_pos - 1, GFP_NOFS);
900 }
901 for (i = 0; i < num_pages; i++) {
902 clear_page_dirty_for_io(pages[i]);
903 set_page_extent_mapped(pages[i]);
904 WARN_ON(!PageLocked(pages[i]));
905 }
906 return 0;
907 }
908
909 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
910 size_t count, loff_t *ppos)
911 {
912 loff_t pos;
913 loff_t start_pos;
914 ssize_t num_written = 0;
915 ssize_t err = 0;
916 int ret = 0;
917 struct inode *inode = fdentry(file)->d_inode;
918 struct btrfs_root *root = BTRFS_I(inode)->root;
919 struct page **pages = NULL;
920 int nrptrs;
921 struct page *pinned[2];
922 unsigned long first_index;
923 unsigned long last_index;
924 int will_write;
925
926 will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
927 (file->f_flags & O_DIRECT));
928
929 nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
930 PAGE_CACHE_SIZE / (sizeof(struct page *)));
931 pinned[0] = NULL;
932 pinned[1] = NULL;
933
934 pos = *ppos;
935 start_pos = pos;
936
937 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
938 current->backing_dev_info = inode->i_mapping->backing_dev_info;
939 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
940 if (err)
941 goto out_nolock;
942 if (count == 0)
943 goto out_nolock;
944
945 err = file_remove_suid(file);
946 if (err)
947 goto out_nolock;
948 file_update_time(file);
949
950 pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
951
952 mutex_lock(&inode->i_mutex);
953 BTRFS_I(inode)->sequence++;
954 first_index = pos >> PAGE_CACHE_SHIFT;
955 last_index = (pos + count) >> PAGE_CACHE_SHIFT;
956
957 /*
958 * there are lots of better ways to do this, but this code
959 * makes sure the first and last page in the file range are
960 * up to date and ready for cow
961 */
962 if ((pos & (PAGE_CACHE_SIZE - 1))) {
963 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
964 if (!PageUptodate(pinned[0])) {
965 ret = btrfs_readpage(NULL, pinned[0]);
966 BUG_ON(ret);
967 wait_on_page_locked(pinned[0]);
968 } else {
969 unlock_page(pinned[0]);
970 }
971 }
972 if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
973 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
974 if (!PageUptodate(pinned[1])) {
975 ret = btrfs_readpage(NULL, pinned[1]);
976 BUG_ON(ret);
977 wait_on_page_locked(pinned[1]);
978 } else {
979 unlock_page(pinned[1]);
980 }
981 }
982
983 while (count > 0) {
984 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
985 size_t write_bytes = min(count, nrptrs *
986 (size_t)PAGE_CACHE_SIZE -
987 offset);
988 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
989 PAGE_CACHE_SHIFT;
990
991 WARN_ON(num_pages > nrptrs);
992 memset(pages, 0, sizeof(struct page *) * nrptrs);
993
994 ret = btrfs_check_data_free_space(root, inode, write_bytes);
995 if (ret)
996 goto out;
997
998 ret = prepare_pages(root, file, pages, num_pages,
999 pos, first_index, last_index,
1000 write_bytes);
1001 if (ret) {
1002 btrfs_free_reserved_data_space(root, inode,
1003 write_bytes);
1004 goto out;
1005 }
1006
1007 ret = btrfs_copy_from_user(pos, num_pages,
1008 write_bytes, pages, buf);
1009 if (ret) {
1010 btrfs_free_reserved_data_space(root, inode,
1011 write_bytes);
1012 btrfs_drop_pages(pages, num_pages);
1013 goto out;
1014 }
1015
1016 ret = dirty_and_release_pages(NULL, root, file, pages,
1017 num_pages, pos, write_bytes);
1018 btrfs_drop_pages(pages, num_pages);
1019 if (ret) {
1020 btrfs_free_reserved_data_space(root, inode,
1021 write_bytes);
1022 goto out;
1023 }
1024
1025 if (will_write) {
1026 btrfs_fdatawrite_range(inode->i_mapping, pos,
1027 pos + write_bytes - 1,
1028 WB_SYNC_ALL);
1029 } else {
1030 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1031 num_pages);
1032 if (num_pages <
1033 (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1034 btrfs_btree_balance_dirty(root, 1);
1035 btrfs_throttle(root);
1036 }
1037
1038 buf += write_bytes;
1039 count -= write_bytes;
1040 pos += write_bytes;
1041 num_written += write_bytes;
1042
1043 cond_resched();
1044 }
1045 out:
1046 mutex_unlock(&inode->i_mutex);
1047 if (ret)
1048 err = ret;
1049
1050 out_nolock:
1051 kfree(pages);
1052 if (pinned[0])
1053 page_cache_release(pinned[0]);
1054 if (pinned[1])
1055 page_cache_release(pinned[1]);
1056 *ppos = pos;
1057
1058 /*
1059 * we want to make sure fsync finds this change
1060 * but we haven't joined a transaction running right now.
1061 *
1062 * Later on, someone is sure to update the inode and get the
1063 * real transid recorded.
1064 *
1065 * We set last_trans now to the fs_info generation + 1,
1066 * this will either be one more than the running transaction
1067 * or the generation used for the next transaction if there isn't
1068 * one running right now.
1069 */
1070 BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1071
1072 if (num_written > 0 && will_write) {
1073 struct btrfs_trans_handle *trans;
1074
1075 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1076 if (err)
1077 num_written = err;
1078
1079 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1080 trans = btrfs_start_transaction(root, 1);
1081 ret = btrfs_log_dentry_safe(trans, root,
1082 file->f_dentry);
1083 if (ret == 0) {
1084 ret = btrfs_sync_log(trans, root);
1085 if (ret == 0)
1086 btrfs_end_transaction(trans, root);
1087 else
1088 btrfs_commit_transaction(trans, root);
1089 } else {
1090 btrfs_commit_transaction(trans, root);
1091 }
1092 }
1093 if (file->f_flags & O_DIRECT) {
1094 invalidate_mapping_pages(inode->i_mapping,
1095 start_pos >> PAGE_CACHE_SHIFT,
1096 (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1097 }
1098 }
1099 current->backing_dev_info = NULL;
1100 return num_written ? num_written : err;
1101 }
1102
1103 int btrfs_release_file(struct inode *inode, struct file *filp)
1104 {
1105 /*
1106 * ordered_data_close is set by settattr when we are about to truncate
1107 * a file from a non-zero size to a zero size. This tries to
1108 * flush down new bytes that may have been written if the
1109 * application were using truncate to replace a file in place.
1110 */
1111 if (BTRFS_I(inode)->ordered_data_close) {
1112 BTRFS_I(inode)->ordered_data_close = 0;
1113 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1114 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1115 filemap_flush(inode->i_mapping);
1116 }
1117 if (filp->private_data)
1118 btrfs_ioctl_trans_end(filp);
1119 return 0;
1120 }
1121
1122 /*
1123 * fsync call for both files and directories. This logs the inode into
1124 * the tree log instead of forcing full commits whenever possible.
1125 *
1126 * It needs to call filemap_fdatawait so that all ordered extent updates are
1127 * in the metadata btree are up to date for copying to the log.
1128 *
1129 * It drops the inode mutex before doing the tree log commit. This is an
1130 * important optimization for directories because holding the mutex prevents
1131 * new operations on the dir while we write to disk.
1132 */
1133 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1134 {
1135 struct inode *inode = dentry->d_inode;
1136 struct btrfs_root *root = BTRFS_I(inode)->root;
1137 int ret = 0;
1138 struct btrfs_trans_handle *trans;
1139
1140 /*
1141 * check the transaction that last modified this inode
1142 * and see if its already been committed
1143 */
1144 if (!BTRFS_I(inode)->last_trans)
1145 goto out;
1146
1147 mutex_lock(&root->fs_info->trans_mutex);
1148 if (BTRFS_I(inode)->last_trans <=
1149 root->fs_info->last_trans_committed) {
1150 BTRFS_I(inode)->last_trans = 0;
1151 mutex_unlock(&root->fs_info->trans_mutex);
1152 goto out;
1153 }
1154 mutex_unlock(&root->fs_info->trans_mutex);
1155
1156 root->log_batch++;
1157 filemap_fdatawrite(inode->i_mapping);
1158 btrfs_wait_ordered_range(inode, 0, (u64)-1);
1159 root->log_batch++;
1160
1161 if (datasync && !(inode->i_state & I_DIRTY_PAGES))
1162 goto out;
1163 /*
1164 * ok we haven't committed the transaction yet, lets do a commit
1165 */
1166 if (file && file->private_data)
1167 btrfs_ioctl_trans_end(file);
1168
1169 trans = btrfs_start_transaction(root, 1);
1170 if (!trans) {
1171 ret = -ENOMEM;
1172 goto out;
1173 }
1174
1175 ret = btrfs_log_dentry_safe(trans, root, dentry);
1176 if (ret < 0)
1177 goto out;
1178
1179 /* we've logged all the items and now have a consistent
1180 * version of the file in the log. It is possible that
1181 * someone will come in and modify the file, but that's
1182 * fine because the log is consistent on disk, and we
1183 * have references to all of the file's extents
1184 *
1185 * It is possible that someone will come in and log the
1186 * file again, but that will end up using the synchronization
1187 * inside btrfs_sync_log to keep things safe.
1188 */
1189 mutex_unlock(&dentry->d_inode->i_mutex);
1190
1191 if (ret > 0) {
1192 ret = btrfs_commit_transaction(trans, root);
1193 } else {
1194 ret = btrfs_sync_log(trans, root);
1195 if (ret == 0)
1196 ret = btrfs_end_transaction(trans, root);
1197 else
1198 ret = btrfs_commit_transaction(trans, root);
1199 }
1200 mutex_lock(&dentry->d_inode->i_mutex);
1201 out:
1202 return ret > 0 ? EIO : ret;
1203 }
1204
1205 static struct vm_operations_struct btrfs_file_vm_ops = {
1206 .fault = filemap_fault,
1207 .page_mkwrite = btrfs_page_mkwrite,
1208 };
1209
1210 static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma)
1211 {
1212 vma->vm_ops = &btrfs_file_vm_ops;
1213 file_accessed(filp);
1214 return 0;
1215 }
1216
1217 struct file_operations btrfs_file_operations = {
1218 .llseek = generic_file_llseek,
1219 .read = do_sync_read,
1220 .aio_read = generic_file_aio_read,
1221 .splice_read = generic_file_splice_read,
1222 .write = btrfs_file_write,
1223 .mmap = btrfs_file_mmap,
1224 .open = generic_file_open,
1225 .release = btrfs_release_file,
1226 .fsync = btrfs_sync_file,
1227 .unlocked_ioctl = btrfs_ioctl,
1228 #ifdef CONFIG_COMPAT
1229 .compat_ioctl = btrfs_ioctl,
1230 #endif
1231 };
Linux kernel - Deliverables
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