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KVM: Prevent kvm_init from corrupting debugfs structures
[linux-2.6/verdex.git] / fs / btrfs / free-space-cache.c
blob5edcee3a617f44e4608cefd709a6e8d7c38e14a5
1 /*
2 * Copyright (C) 2008 Red Hat. 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/pagemap.h>
20 #include <linux/sched.h>
21 #include <linux/math64.h>
22 #include "ctree.h"
23 #include "free-space-cache.h"
24 #include "transaction.h"
25
26 #define BITS_PER_BITMAP (PAGE_CACHE_SIZE * 8)
27 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
28
29 static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
30 u64 offset)
31 {
32 BUG_ON(offset < bitmap_start);
33 offset -= bitmap_start;
34 return (unsigned long)(div64_u64(offset, sectorsize));
35 }
36
37 static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize)
38 {
39 return (unsigned long)(div64_u64(bytes, sectorsize));
40 }
41
42 static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group,
43 u64 offset)
44 {
45 u64 bitmap_start;
46 u64 bytes_per_bitmap;
47
48 bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize;
49 bitmap_start = offset - block_group->key.objectid;
50 bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
51 bitmap_start *= bytes_per_bitmap;
52 bitmap_start += block_group->key.objectid;
53
54 return bitmap_start;
55 }
56
57 static int tree_insert_offset(struct rb_root *root, u64 offset,
58 struct rb_node *node, int bitmap)
59 {
60 struct rb_node **p = &root->rb_node;
61 struct rb_node *parent = NULL;
62 struct btrfs_free_space *info;
63
64 while (*p) {
65 parent = *p;
66 info = rb_entry(parent, struct btrfs_free_space, offset_index);
67
68 if (offset < info->offset) {
69 p = &(*p)->rb_left;
70 } else if (offset > info->offset) {
71 p = &(*p)->rb_right;
72 } else {
73 /*
74 * we could have a bitmap entry and an extent entry
75 * share the same offset. If this is the case, we want
76 * the extent entry to always be found first if we do a
77 * linear search through the tree, since we want to have
78 * the quickest allocation time, and allocating from an
79 * extent is faster than allocating from a bitmap. So
80 * if we're inserting a bitmap and we find an entry at
81 * this offset, we want to go right, or after this entry
82 * logically. If we are inserting an extent and we've
83 * found a bitmap, we want to go left, or before
84 * logically.
85 */
86 if (bitmap) {
87 WARN_ON(info->bitmap);
88 p = &(*p)->rb_right;
89 } else {
90 WARN_ON(!info->bitmap);
91 p = &(*p)->rb_left;
92 }
93 }
94 }
95
96 rb_link_node(node, parent, p);
97 rb_insert_color(node, root);
98
99 return 0;
100 }
101
102 /*
103 * searches the tree for the given offset.
104 *
105 * fuzzy - If this is set, then we are trying to make an allocation, and we just
106 * want a section that has at least bytes size and comes at or after the given
107 * offset.
108 */
109 static struct btrfs_free_space *
110 tree_search_offset(struct btrfs_block_group_cache *block_group,
111 u64 offset, int bitmap_only, int fuzzy)
112 {
113 struct rb_node *n = block_group->free_space_offset.rb_node;
114 struct btrfs_free_space *entry, *prev = NULL;
115
116 /* find entry that is closest to the 'offset' */
117 while (1) {
118 if (!n) {
119 entry = NULL;
120 break;
121 }
122
123 entry = rb_entry(n, struct btrfs_free_space, offset_index);
124 prev = entry;
125
126 if (offset < entry->offset)
127 n = n->rb_left;
128 else if (offset > entry->offset)
129 n = n->rb_right;
130 else
131 break;
132 }
133
134 if (bitmap_only) {
135 if (!entry)
136 return NULL;
137 if (entry->bitmap)
138 return entry;
139
140 /*
141 * bitmap entry and extent entry may share same offset,
142 * in that case, bitmap entry comes after extent entry.
143 */
144 n = rb_next(n);
145 if (!n)
146 return NULL;
147 entry = rb_entry(n, struct btrfs_free_space, offset_index);
148 if (entry->offset != offset)
149 return NULL;
150
151 WARN_ON(!entry->bitmap);
152 return entry;
153 } else if (entry) {
154 if (entry->bitmap) {
155 /*
156 * if previous extent entry covers the offset,
157 * we should return it instead of the bitmap entry
158 */
159 n = &entry->offset_index;
160 while (1) {
161 n = rb_prev(n);
162 if (!n)
163 break;
164 prev = rb_entry(n, struct btrfs_free_space,
165 offset_index);
166 if (!prev->bitmap) {
167 if (prev->offset + prev->bytes > offset)
168 entry = prev;
169 break;
170 }
171 }
172 }
173 return entry;
174 }
175
176 if (!prev)
177 return NULL;
178
179 /* find last entry before the 'offset' */
180 entry = prev;
181 if (entry->offset > offset) {
182 n = rb_prev(&entry->offset_index);
183 if (n) {
184 entry = rb_entry(n, struct btrfs_free_space,
185 offset_index);
186 BUG_ON(entry->offset > offset);
187 } else {
188 if (fuzzy)
189 return entry;
190 else
191 return NULL;
192 }
193 }
194
195 if (entry->bitmap) {
196 n = &entry->offset_index;
197 while (1) {
198 n = rb_prev(n);
199 if (!n)
200 break;
201 prev = rb_entry(n, struct btrfs_free_space,
202 offset_index);
203 if (!prev->bitmap) {
204 if (prev->offset + prev->bytes > offset)
205 return prev;
206 break;
207 }
208 }
209 if (entry->offset + BITS_PER_BITMAP *
210 block_group->sectorsize > offset)
211 return entry;
212 } else if (entry->offset + entry->bytes > offset)
213 return entry;
214
215 if (!fuzzy)
216 return NULL;
217
218 while (1) {
219 if (entry->bitmap) {
220 if (entry->offset + BITS_PER_BITMAP *
221 block_group->sectorsize > offset)
222 break;
223 } else {
224 if (entry->offset + entry->bytes > offset)
225 break;
226 }
227
228 n = rb_next(&entry->offset_index);
229 if (!n)
230 return NULL;
231 entry = rb_entry(n, struct btrfs_free_space, offset_index);
232 }
233 return entry;
234 }
235
236 static void unlink_free_space(struct btrfs_block_group_cache *block_group,
237 struct btrfs_free_space *info)
238 {
239 rb_erase(&info->offset_index, &block_group->free_space_offset);
240 block_group->free_extents--;
241 block_group->free_space -= info->bytes;
242 }
243
244 static int link_free_space(struct btrfs_block_group_cache *block_group,
245 struct btrfs_free_space *info)
246 {
247 int ret = 0;
248
249 BUG_ON(!info->bitmap && !info->bytes);
250 ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
251 &info->offset_index, (info->bitmap != NULL));
252 if (ret)
253 return ret;
254
255 block_group->free_space += info->bytes;
256 block_group->free_extents++;
257 return ret;
258 }
259
260 static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
261 {
262 u64 max_bytes, possible_bytes;
263
264 /*
265 * The goal is to keep the total amount of memory used per 1gb of space
266 * at or below 32k, so we need to adjust how much memory we allow to be
267 * used by extent based free space tracking
268 */
269 max_bytes = MAX_CACHE_BYTES_PER_GIG *
270 (div64_u64(block_group->key.offset, 1024 * 1024 * 1024));
271
272 possible_bytes = (block_group->total_bitmaps * PAGE_CACHE_SIZE) +
273 (sizeof(struct btrfs_free_space) *
274 block_group->extents_thresh);
275
276 if (possible_bytes > max_bytes) {
277 int extent_bytes = max_bytes -
278 (block_group->total_bitmaps * PAGE_CACHE_SIZE);
279
280 if (extent_bytes <= 0) {
281 block_group->extents_thresh = 0;
282 return;
283 }
284
285 block_group->extents_thresh = extent_bytes /
286 (sizeof(struct btrfs_free_space));
287 }
288 }
289
290 static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
291 struct btrfs_free_space *info, u64 offset,
292 u64 bytes)
293 {
294 unsigned long start, end;
295 unsigned long i;
296
297 start = offset_to_bit(info->offset, block_group->sectorsize, offset);
298 end = start + bytes_to_bits(bytes, block_group->sectorsize);
299 BUG_ON(end > BITS_PER_BITMAP);
300
301 for (i = start; i < end; i++)
302 clear_bit(i, info->bitmap);
303
304 info->bytes -= bytes;
305 block_group->free_space -= bytes;
306 }
307
308 static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
309 struct btrfs_free_space *info, u64 offset,
310 u64 bytes)
311 {
312 unsigned long start, end;
313 unsigned long i;
314
315 start = offset_to_bit(info->offset, block_group->sectorsize, offset);
316 end = start + bytes_to_bits(bytes, block_group->sectorsize);
317 BUG_ON(end > BITS_PER_BITMAP);
318
319 for (i = start; i < end; i++)
320 set_bit(i, info->bitmap);
321
322 info->bytes += bytes;
323 block_group->free_space += bytes;
324 }
325
326 static int search_bitmap(struct btrfs_block_group_cache *block_group,
327 struct btrfs_free_space *bitmap_info, u64 *offset,
328 u64 *bytes)
329 {
330 unsigned long found_bits = 0;
331 unsigned long bits, i;
332 unsigned long next_zero;
333
334 i = offset_to_bit(bitmap_info->offset, block_group->sectorsize,
335 max_t(u64, *offset, bitmap_info->offset));
336 bits = bytes_to_bits(*bytes, block_group->sectorsize);
337
338 for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
339 i < BITS_PER_BITMAP;
340 i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
341 next_zero = find_next_zero_bit(bitmap_info->bitmap,
342 BITS_PER_BITMAP, i);
343 if ((next_zero - i) >= bits) {
344 found_bits = next_zero - i;
345 break;
346 }
347 i = next_zero;
348 }
349
350 if (found_bits) {
351 *offset = (u64)(i * block_group->sectorsize) +
352 bitmap_info->offset;
353 *bytes = (u64)(found_bits) * block_group->sectorsize;
354 return 0;
355 }
356
357 return -1;
358 }
359
360 static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
361 *block_group, u64 *offset,
362 u64 *bytes, int debug)
363 {
364 struct btrfs_free_space *entry;
365 struct rb_node *node;
366 int ret;
367
368 if (!block_group->free_space_offset.rb_node)
369 return NULL;
370
371 entry = tree_search_offset(block_group,
372 offset_to_bitmap(block_group, *offset),
373 0, 1);
374 if (!entry)
375 return NULL;
376
377 for (node = &entry->offset_index; node; node = rb_next(node)) {
378 entry = rb_entry(node, struct btrfs_free_space, offset_index);
379 if (entry->bytes < *bytes)
380 continue;
381
382 if (entry->bitmap) {
383 ret = search_bitmap(block_group, entry, offset, bytes);
384 if (!ret)
385 return entry;
386 continue;
387 }
388
389 *offset = entry->offset;
390 *bytes = entry->bytes;
391 return entry;
392 }
393
394 return NULL;
395 }
396
397 static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
398 struct btrfs_free_space *info, u64 offset)
399 {
400 u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
401 int max_bitmaps = (int)div64_u64(block_group->key.offset +
402 bytes_per_bg - 1, bytes_per_bg);
403 BUG_ON(block_group->total_bitmaps >= max_bitmaps);
404
405 info->offset = offset_to_bitmap(block_group, offset);
406 link_free_space(block_group, info);
407 block_group->total_bitmaps++;
408
409 recalculate_thresholds(block_group);
410 }
411
412 static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
413 struct btrfs_free_space *bitmap_info,
414 u64 *offset, u64 *bytes)
415 {
416 u64 end;
417 u64 search_start, search_bytes;
418 int ret;
419
420 again:
421 end = bitmap_info->offset +
422 (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
423
424 /*
425 * XXX - this can go away after a few releases.
426 *
427 * since the only user of btrfs_remove_free_space is the tree logging
428 * stuff, and the only way to test that is under crash conditions, we
429 * want to have this debug stuff here just in case somethings not
430 * working. Search the bitmap for the space we are trying to use to
431 * make sure its actually there. If its not there then we need to stop
432 * because something has gone wrong.
433 */
434 search_start = *offset;
435 search_bytes = *bytes;
436 ret = search_bitmap(block_group, bitmap_info, &search_start,
437 &search_bytes);
438 BUG_ON(ret < 0 || search_start != *offset);
439
440 if (*offset > bitmap_info->offset && *offset + *bytes > end) {
441 bitmap_clear_bits(block_group, bitmap_info, *offset,
442 end - *offset + 1);
443 *bytes -= end - *offset + 1;
444 *offset = end + 1;
445 } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
446 bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
447 *bytes = 0;
448 }
449
450 if (*bytes) {
451 struct rb_node *next = rb_next(&bitmap_info->offset_index);
452 if (!bitmap_info->bytes) {
453 unlink_free_space(block_group, bitmap_info);
454 kfree(bitmap_info->bitmap);
455 kfree(bitmap_info);
456 block_group->total_bitmaps--;
457 recalculate_thresholds(block_group);
458 }
459
460 /*
461 * no entry after this bitmap, but we still have bytes to
462 * remove, so something has gone wrong.
463 */
464 if (!next)
465 return -EINVAL;
466
467 bitmap_info = rb_entry(next, struct btrfs_free_space,
468 offset_index);
469
470 /*
471 * if the next entry isn't a bitmap we need to return to let the
472 * extent stuff do its work.
473 */
474 if (!bitmap_info->bitmap)
475 return -EAGAIN;
476
477 /*
478 * Ok the next item is a bitmap, but it may not actually hold
479 * the information for the rest of this free space stuff, so
480 * look for it, and if we don't find it return so we can try
481 * everything over again.
482 */
483 search_start = *offset;
484 search_bytes = *bytes;
485 ret = search_bitmap(block_group, bitmap_info, &search_start,
486 &search_bytes);
487 if (ret < 0 || search_start != *offset)
488 return -EAGAIN;
489
490 goto again;
491 } else if (!bitmap_info->bytes) {
492 unlink_free_space(block_group, bitmap_info);
493 kfree(bitmap_info->bitmap);
494 kfree(bitmap_info);
495 block_group->total_bitmaps--;
496 recalculate_thresholds(block_group);
497 }
498
499 return 0;
500 }
501
502 static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
503 struct btrfs_free_space *info)
504 {
505 struct btrfs_free_space *bitmap_info;
506 int added = 0;
507 u64 bytes, offset, end;
508 int ret;
509
510 /*
511 * If we are below the extents threshold then we can add this as an
512 * extent, and don't have to deal with the bitmap
513 */
514 if (block_group->free_extents < block_group->extents_thresh &&
515 info->bytes > block_group->sectorsize * 4)
516 return 0;
517
518 /*
519 * some block groups are so tiny they can't be enveloped by a bitmap, so
520 * don't even bother to create a bitmap for this
521 */
522 if (BITS_PER_BITMAP * block_group->sectorsize >
523 block_group->key.offset)
524 return 0;
525
526 bytes = info->bytes;
527 offset = info->offset;
528
529 again:
530 bitmap_info = tree_search_offset(block_group,
531 offset_to_bitmap(block_group, offset),
532 1, 0);
533 if (!bitmap_info) {
534 BUG_ON(added);
535 goto new_bitmap;
536 }
537
538 end = bitmap_info->offset +
539 (u64)(BITS_PER_BITMAP * block_group->sectorsize);
540
541 if (offset >= bitmap_info->offset && offset + bytes > end) {
542 bitmap_set_bits(block_group, bitmap_info, offset,
543 end - offset);
544 bytes -= end - offset;
545 offset = end;
546 added = 0;
547 } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
548 bitmap_set_bits(block_group, bitmap_info, offset, bytes);
549 bytes = 0;
550 } else {
551 BUG();
552 }
553
554 if (!bytes) {
555 ret = 1;
556 goto out;
557 } else
558 goto again;
559
560 new_bitmap:
561 if (info && info->bitmap) {
562 add_new_bitmap(block_group, info, offset);
563 added = 1;
564 info = NULL;
565 goto again;
566 } else {
567 spin_unlock(&block_group->tree_lock);
568
569 /* no pre-allocated info, allocate a new one */
570 if (!info) {
571 info = kzalloc(sizeof(struct btrfs_free_space),
572 GFP_NOFS);
573 if (!info) {
574 spin_lock(&block_group->tree_lock);
575 ret = -ENOMEM;
576 goto out;
577 }
578 }
579
580 /* allocate the bitmap */
581 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
582 spin_lock(&block_group->tree_lock);
583 if (!info->bitmap) {
584 ret = -ENOMEM;
585 goto out;
586 }
587 goto again;
588 }
589
590 out:
591 if (info) {
592 if (info->bitmap)
593 kfree(info->bitmap);
594 kfree(info);
595 }
596
597 return ret;
598 }
599
600 int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
601 u64 offset, u64 bytes)
602 {
603 struct btrfs_free_space *right_info = NULL;
604 struct btrfs_free_space *left_info = NULL;
605 struct btrfs_free_space *info = NULL;
606 int ret = 0;
607
608 info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
609 if (!info)
610 return -ENOMEM;
611
612 info->offset = offset;
613 info->bytes = bytes;
614
615 spin_lock(&block_group->tree_lock);
616
617 /*
618 * first we want to see if there is free space adjacent to the range we
619 * are adding, if there is remove that struct and add a new one to
620 * cover the entire range
621 */
622 right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
623 if (right_info && rb_prev(&right_info->offset_index))
624 left_info = rb_entry(rb_prev(&right_info->offset_index),
625 struct btrfs_free_space, offset_index);
626 else
627 left_info = tree_search_offset(block_group, offset - 1, 0, 0);
628
629 /*
630 * If there was no extent directly to the left or right of this new
631 * extent then we know we're going to have to allocate a new extent, so
632 * before we do that see if we need to drop this into a bitmap
633 */
634 if ((!left_info || left_info->bitmap) &&
635 (!right_info || right_info->bitmap)) {
636 ret = insert_into_bitmap(block_group, info);
637
638 if (ret < 0) {
639 goto out;
640 } else if (ret) {
641 ret = 0;
642 goto out;
643 }
644 }
645
646 if (right_info && !right_info->bitmap) {
647 unlink_free_space(block_group, right_info);
648 info->bytes += right_info->bytes;
649 kfree(right_info);
650 }
651
652 if (left_info && !left_info->bitmap &&
653 left_info->offset + left_info->bytes == offset) {
654 unlink_free_space(block_group, left_info);
655 info->offset = left_info->offset;
656 info->bytes += left_info->bytes;
657 kfree(left_info);
658 }
659
660 ret = link_free_space(block_group, info);
661 if (ret)
662 kfree(info);
663 out:
664 spin_unlock(&block_group->tree_lock);
665
666 if (ret) {
667 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
668 BUG_ON(ret == -EEXIST);
669 }
670
671 return ret;
672 }
673
674 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
675 u64 offset, u64 bytes)
676 {
677 struct btrfs_free_space *info;
678 struct btrfs_free_space *next_info = NULL;
679 int ret = 0;
680
681 spin_lock(&block_group->tree_lock);
682
683 again:
684 info = tree_search_offset(block_group, offset, 0, 0);
685 if (!info) {
686 /*
687 * oops didn't find an extent that matched the space we wanted
688 * to remove, look for a bitmap instead
689 */
690 info = tree_search_offset(block_group,
691 offset_to_bitmap(block_group, offset),
692 1, 0);
693 if (!info) {
694 WARN_ON(1);
695 goto out_lock;
696 }
697 }
698
699 if (info->bytes < bytes && rb_next(&info->offset_index)) {
700 u64 end;
701 next_info = rb_entry(rb_next(&info->offset_index),
702 struct btrfs_free_space,
703 offset_index);
704
705 if (next_info->bitmap)
706 end = next_info->offset + BITS_PER_BITMAP *
707 block_group->sectorsize - 1;
708 else
709 end = next_info->offset + next_info->bytes;
710
711 if (next_info->bytes < bytes ||
712 next_info->offset > offset || offset > end) {
713 printk(KERN_CRIT "Found free space at %llu, size %llu,"
714 " trying to use %llu\n",
715 (unsigned long long)info->offset,
716 (unsigned long long)info->bytes,
717 (unsigned long long)bytes);
718 WARN_ON(1);
719 ret = -EINVAL;
720 goto out_lock;
721 }
722
723 info = next_info;
724 }
725
726 if (info->bytes == bytes) {
727 unlink_free_space(block_group, info);
728 if (info->bitmap) {
729 kfree(info->bitmap);
730 block_group->total_bitmaps--;
731 }
732 kfree(info);
733 goto out_lock;
734 }
735
736 if (!info->bitmap && info->offset == offset) {
737 unlink_free_space(block_group, info);
738 info->offset += bytes;
739 info->bytes -= bytes;
740 link_free_space(block_group, info);
741 goto out_lock;
742 }
743
744 if (!info->bitmap && info->offset <= offset &&
745 info->offset + info->bytes >= offset + bytes) {
746 u64 old_start = info->offset;
747 /*
748 * we're freeing space in the middle of the info,
749 * this can happen during tree log replay
750 *
751 * first unlink the old info and then
752 * insert it again after the hole we're creating
753 */
754 unlink_free_space(block_group, info);
755 if (offset + bytes < info->offset + info->bytes) {
756 u64 old_end = info->offset + info->bytes;
757
758 info->offset = offset + bytes;
759 info->bytes = old_end - info->offset;
760 ret = link_free_space(block_group, info);
761 WARN_ON(ret);
762 if (ret)
763 goto out_lock;
764 } else {
765 /* the hole we're creating ends at the end
766 * of the info struct, just free the info
767 */
768 kfree(info);
769 }
770 spin_unlock(&block_group->tree_lock);
771
772 /* step two, insert a new info struct to cover
773 * anything before the hole
774 */
775 ret = btrfs_add_free_space(block_group, old_start,
776 offset - old_start);
777 WARN_ON(ret);
778 goto out;
779 }
780
781 ret = remove_from_bitmap(block_group, info, &offset, &bytes);
782 if (ret == -EAGAIN)
783 goto again;
784 BUG_ON(ret);
785 out_lock:
786 spin_unlock(&block_group->tree_lock);
787 out:
788 return ret;
789 }
790
791 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
792 u64 bytes)
793 {
794 struct btrfs_free_space *info;
795 struct rb_node *n;
796 int count = 0;
797
798 for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
799 info = rb_entry(n, struct btrfs_free_space, offset_index);
800 if (info->bytes >= bytes)
801 count++;
802 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
803 (unsigned long long)info->offset,
804 (unsigned long long)info->bytes,
805 (info->bitmap) ? "yes" : "no");
806 }
807 printk(KERN_INFO "block group has cluster?: %s\n",
808 list_empty(&block_group->cluster_list) ? "no" : "yes");
809 printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
810 "\n", count);
811 }
812
813 u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
814 {
815 struct btrfs_free_space *info;
816 struct rb_node *n;
817 u64 ret = 0;
818
819 for (n = rb_first(&block_group->free_space_offset); n;
820 n = rb_next(n)) {
821 info = rb_entry(n, struct btrfs_free_space, offset_index);
822 ret += info->bytes;
823 }
824
825 return ret;
826 }
827
828 /*
829 * for a given cluster, put all of its extents back into the free
830 * space cache. If the block group passed doesn't match the block group
831 * pointed to by the cluster, someone else raced in and freed the
832 * cluster already. In that case, we just return without changing anything
833 */
834 static int
835 __btrfs_return_cluster_to_free_space(
836 struct btrfs_block_group_cache *block_group,
837 struct btrfs_free_cluster *cluster)
838 {
839 struct btrfs_free_space *entry;
840 struct rb_node *node;
841 bool bitmap;
842
843 spin_lock(&cluster->lock);
844 if (cluster->block_group != block_group)
845 goto out;
846
847 bitmap = cluster->points_to_bitmap;
848 cluster->block_group = NULL;
849 cluster->window_start = 0;
850 list_del_init(&cluster->block_group_list);
851 cluster->points_to_bitmap = false;
852
853 if (bitmap)
854 goto out;
855
856 node = rb_first(&cluster->root);
857 while (node) {
858 entry = rb_entry(node, struct btrfs_free_space, offset_index);
859 node = rb_next(&entry->offset_index);
860 rb_erase(&entry->offset_index, &cluster->root);
861 BUG_ON(entry->bitmap);
862 tree_insert_offset(&block_group->free_space_offset,
863 entry->offset, &entry->offset_index, 0);
864 }
865 cluster->root.rb_node = NULL;
866
867 out:
868 spin_unlock(&cluster->lock);
869 btrfs_put_block_group(block_group);
870 return 0;
871 }
872
873 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
874 {
875 struct btrfs_free_space *info;
876 struct rb_node *node;
877 struct btrfs_free_cluster *cluster;
878 struct list_head *head;
879
880 spin_lock(&block_group->tree_lock);
881 while ((head = block_group->cluster_list.next) !=
882 &block_group->cluster_list) {
883 cluster = list_entry(head, struct btrfs_free_cluster,
884 block_group_list);
885
886 WARN_ON(cluster->block_group != block_group);
887 __btrfs_return_cluster_to_free_space(block_group, cluster);
888 if (need_resched()) {
889 spin_unlock(&block_group->tree_lock);
890 cond_resched();
891 spin_lock(&block_group->tree_lock);
892 }
893 }
894
895 while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
896 info = rb_entry(node, struct btrfs_free_space, offset_index);
897 unlink_free_space(block_group, info);
898 if (info->bitmap)
899 kfree(info->bitmap);
900 kfree(info);
901 if (need_resched()) {
902 spin_unlock(&block_group->tree_lock);
903 cond_resched();
904 spin_lock(&block_group->tree_lock);
905 }
906 }
907
908 spin_unlock(&block_group->tree_lock);
909 }
910
911 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
912 u64 offset, u64 bytes, u64 empty_size)
913 {
914 struct btrfs_free_space *entry = NULL;
915 u64 bytes_search = bytes + empty_size;
916 u64 ret = 0;
917
918 spin_lock(&block_group->tree_lock);
919 entry = find_free_space(block_group, &offset, &bytes_search, 0);
920 if (!entry)
921 goto out;
922
923 ret = offset;
924 if (entry->bitmap) {
925 bitmap_clear_bits(block_group, entry, offset, bytes);
926 if (!entry->bytes) {
927 unlink_free_space(block_group, entry);
928 kfree(entry->bitmap);
929 kfree(entry);
930 block_group->total_bitmaps--;
931 recalculate_thresholds(block_group);
932 }
933 } else {
934 unlink_free_space(block_group, entry);
935 entry->offset += bytes;
936 entry->bytes -= bytes;
937 if (!entry->bytes)
938 kfree(entry);
939 else
940 link_free_space(block_group, entry);
941 }
942
943 out:
944 spin_unlock(&block_group->tree_lock);
945
946 return ret;
947 }
948
949 /*
950 * given a cluster, put all of its extents back into the free space
951 * cache. If a block group is passed, this function will only free
952 * a cluster that belongs to the passed block group.
953 *
954 * Otherwise, it'll get a reference on the block group pointed to by the
955 * cluster and remove the cluster from it.
956 */
957 int btrfs_return_cluster_to_free_space(
958 struct btrfs_block_group_cache *block_group,
959 struct btrfs_free_cluster *cluster)
960 {
961 int ret;
962
963 /* first, get a safe pointer to the block group */
964 spin_lock(&cluster->lock);
965 if (!block_group) {
966 block_group = cluster->block_group;
967 if (!block_group) {
968 spin_unlock(&cluster->lock);
969 return 0;
970 }
971 } else if (cluster->block_group != block_group) {
972 /* someone else has already freed it don't redo their work */
973 spin_unlock(&cluster->lock);
974 return 0;
975 }
976 atomic_inc(&block_group->count);
977 spin_unlock(&cluster->lock);
978
979 /* now return any extents the cluster had on it */
980 spin_lock(&block_group->tree_lock);
981 ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
982 spin_unlock(&block_group->tree_lock);
983
984 /* finally drop our ref */
985 btrfs_put_block_group(block_group);
986 return ret;
987 }
988
989 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
990 struct btrfs_free_cluster *cluster,
991 u64 bytes, u64 min_start)
992 {
993 struct btrfs_free_space *entry;
994 int err;
995 u64 search_start = cluster->window_start;
996 u64 search_bytes = bytes;
997 u64 ret = 0;
998
999 spin_lock(&block_group->tree_lock);
1000 spin_lock(&cluster->lock);
1001
1002 if (!cluster->points_to_bitmap)
1003 goto out;
1004
1005 if (cluster->block_group != block_group)
1006 goto out;
1007
1008 /*
1009 * search_start is the beginning of the bitmap, but at some point it may
1010 * be a good idea to point to the actual start of the free area in the
1011 * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
1012 * to 1 to make sure we get the bitmap entry
1013 */
1014 entry = tree_search_offset(block_group,
1015 offset_to_bitmap(block_group, search_start),
1016 1, 0);
1017 if (!entry || !entry->bitmap)
1018 goto out;
1019
1020 search_start = min_start;
1021 search_bytes = bytes;
1022
1023 err = search_bitmap(block_group, entry, &search_start,
1024 &search_bytes);
1025 if (err)
1026 goto out;
1027
1028 ret = search_start;
1029 bitmap_clear_bits(block_group, entry, ret, bytes);
1030 out:
1031 spin_unlock(&cluster->lock);
1032 spin_unlock(&block_group->tree_lock);
1033
1034 return ret;
1035 }
1036
1037 /*
1038 * given a cluster, try to allocate 'bytes' from it, returns 0
1039 * if it couldn't find anything suitably large, or a logical disk offset
1040 * if things worked out
1041 */
1042 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1043 struct btrfs_free_cluster *cluster, u64 bytes,
1044 u64 min_start)
1045 {
1046 struct btrfs_free_space *entry = NULL;
1047 struct rb_node *node;
1048 u64 ret = 0;
1049
1050 if (cluster->points_to_bitmap)
1051 return btrfs_alloc_from_bitmap(block_group, cluster, bytes,
1052 min_start);
1053
1054 spin_lock(&cluster->lock);
1055 if (bytes > cluster->max_size)
1056 goto out;
1057
1058 if (cluster->block_group != block_group)
1059 goto out;
1060
1061 node = rb_first(&cluster->root);
1062 if (!node)
1063 goto out;
1064
1065 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1066
1067 while(1) {
1068 if (entry->bytes < bytes || entry->offset < min_start) {
1069 struct rb_node *node;
1070
1071 node = rb_next(&entry->offset_index);
1072 if (!node)
1073 break;
1074 entry = rb_entry(node, struct btrfs_free_space,
1075 offset_index);
1076 continue;
1077 }
1078 ret = entry->offset;
1079
1080 entry->offset += bytes;
1081 entry->bytes -= bytes;
1082
1083 if (entry->bytes == 0) {
1084 rb_erase(&entry->offset_index, &cluster->root);
1085 kfree(entry);
1086 }
1087 break;
1088 }
1089 out:
1090 spin_unlock(&cluster->lock);
1091
1092 return ret;
1093 }
1094
1095 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
1096 struct btrfs_free_space *entry,
1097 struct btrfs_free_cluster *cluster,
1098 u64 offset, u64 bytes, u64 min_bytes)
1099 {
1100 unsigned long next_zero;
1101 unsigned long i;
1102 unsigned long search_bits;
1103 unsigned long total_bits;
1104 unsigned long found_bits;
1105 unsigned long start = 0;
1106 unsigned long total_found = 0;
1107 bool found = false;
1108
1109 i = offset_to_bit(entry->offset, block_group->sectorsize,
1110 max_t(u64, offset, entry->offset));
1111 search_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
1112 total_bits = bytes_to_bits(bytes, block_group->sectorsize);
1113
1114 again:
1115 found_bits = 0;
1116 for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
1117 i < BITS_PER_BITMAP;
1118 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
1119 next_zero = find_next_zero_bit(entry->bitmap,
1120 BITS_PER_BITMAP, i);
1121 if (next_zero - i >= search_bits) {
1122 found_bits = next_zero - i;
1123 break;
1124 }
1125 i = next_zero;
1126 }
1127
1128 if (!found_bits)
1129 return -1;
1130
1131 if (!found) {
1132 start = i;
1133 found = true;
1134 }
1135
1136 total_found += found_bits;
1137
1138 if (cluster->max_size < found_bits * block_group->sectorsize)
1139 cluster->max_size = found_bits * block_group->sectorsize;
1140
1141 if (total_found < total_bits) {
1142 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
1143 if (i - start > total_bits * 2) {
1144 total_found = 0;
1145 cluster->max_size = 0;
1146 found = false;
1147 }
1148 goto again;
1149 }
1150
1151 cluster->window_start = start * block_group->sectorsize +
1152 entry->offset;
1153 cluster->points_to_bitmap = true;
1154
1155 return 0;
1156 }
1157
1158 /*
1159 * here we try to find a cluster of blocks in a block group. The goal
1160 * is to find at least bytes free and up to empty_size + bytes free.
1161 * We might not find them all in one contiguous area.
1162 *
1163 * returns zero and sets up cluster if things worked out, otherwise
1164 * it returns -enospc
1165 */
1166 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
1167 struct btrfs_root *root,
1168 struct btrfs_block_group_cache *block_group,
1169 struct btrfs_free_cluster *cluster,
1170 u64 offset, u64 bytes, u64 empty_size)
1171 {
1172 struct btrfs_free_space *entry = NULL;
1173 struct rb_node *node;
1174 struct btrfs_free_space *next;
1175 struct btrfs_free_space *last = NULL;
1176 u64 min_bytes;
1177 u64 window_start;
1178 u64 window_free;
1179 u64 max_extent = 0;
1180 bool found_bitmap = false;
1181 int ret;
1182
1183 /* for metadata, allow allocates with more holes */
1184 if (btrfs_test_opt(root, SSD_SPREAD)) {
1185 min_bytes = bytes + empty_size;
1186 } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
1187 /*
1188 * we want to do larger allocations when we are
1189 * flushing out the delayed refs, it helps prevent
1190 * making more work as we go along.
1191 */
1192 if (trans->transaction->delayed_refs.flushing)
1193 min_bytes = max(bytes, (bytes + empty_size) >> 1);
1194 else
1195 min_bytes = max(bytes, (bytes + empty_size) >> 4);
1196 } else
1197 min_bytes = max(bytes, (bytes + empty_size) >> 2);
1198
1199 spin_lock(&block_group->tree_lock);
1200 spin_lock(&cluster->lock);
1201
1202 /* someone already found a cluster, hooray */
1203 if (cluster->block_group) {
1204 ret = 0;
1205 goto out;
1206 }
1207 again:
1208 entry = tree_search_offset(block_group, offset, found_bitmap, 1);
1209 if (!entry) {
1210 ret = -ENOSPC;
1211 goto out;
1212 }
1213
1214 /*
1215 * If found_bitmap is true, we exhausted our search for extent entries,
1216 * and we just want to search all of the bitmaps that we can find, and
1217 * ignore any extent entries we find.
1218 */
1219 while (entry->bitmap || found_bitmap ||
1220 (!entry->bitmap && entry->bytes < min_bytes)) {
1221 struct rb_node *node = rb_next(&entry->offset_index);
1222
1223 if (entry->bitmap && entry->bytes > bytes + empty_size) {
1224 ret = btrfs_bitmap_cluster(block_group, entry, cluster,
1225 offset, bytes + empty_size,
1226 min_bytes);
1227 if (!ret)
1228 goto got_it;
1229 }
1230
1231 if (!node) {
1232 ret = -ENOSPC;
1233 goto out;
1234 }
1235 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1236 }
1237
1238 /*
1239 * We already searched all the extent entries from the passed in offset
1240 * to the end and didn't find enough space for the cluster, and we also
1241 * didn't find any bitmaps that met our criteria, just go ahead and exit
1242 */
1243 if (found_bitmap) {
1244 ret = -ENOSPC;
1245 goto out;
1246 }
1247
1248 cluster->points_to_bitmap = false;
1249 window_start = entry->offset;
1250 window_free = entry->bytes;
1251 last = entry;
1252 max_extent = entry->bytes;
1253
1254 while (1) {
1255 /* out window is just right, lets fill it */
1256 if (window_free >= bytes + empty_size)
1257 break;
1258
1259 node = rb_next(&last->offset_index);
1260 if (!node) {
1261 if (found_bitmap)
1262 goto again;
1263 ret = -ENOSPC;
1264 goto out;
1265 }
1266 next = rb_entry(node, struct btrfs_free_space, offset_index);
1267
1268 /*
1269 * we found a bitmap, so if this search doesn't result in a
1270 * cluster, we know to go and search again for the bitmaps and
1271 * start looking for space there
1272 */
1273 if (next->bitmap) {
1274 if (!found_bitmap)
1275 offset = next->offset;
1276 found_bitmap = true;
1277 last = next;
1278 continue;
1279 }
1280
1281 /*
1282 * we haven't filled the empty size and the window is
1283 * very large. reset and try again
1284 */
1285 if (next->offset - (last->offset + last->bytes) > 128 * 1024 ||
1286 next->offset - window_start > (bytes + empty_size) * 2) {
1287 entry = next;
1288 window_start = entry->offset;
1289 window_free = entry->bytes;
1290 last = entry;
1291 max_extent = 0;
1292 } else {
1293 last = next;
1294 window_free += next->bytes;
1295 if (entry->bytes > max_extent)
1296 max_extent = entry->bytes;
1297 }
1298 }
1299
1300 cluster->window_start = entry->offset;
1301
1302 /*
1303 * now we've found our entries, pull them out of the free space
1304 * cache and put them into the cluster rbtree
1305 *
1306 * The cluster includes an rbtree, but only uses the offset index
1307 * of each free space cache entry.
1308 */
1309 while (1) {
1310 node = rb_next(&entry->offset_index);
1311 if (entry->bitmap && node) {
1312 entry = rb_entry(node, struct btrfs_free_space,
1313 offset_index);
1314 continue;
1315 } else if (entry->bitmap && !node) {
1316 break;
1317 }
1318
1319 rb_erase(&entry->offset_index, &block_group->free_space_offset);
1320 ret = tree_insert_offset(&cluster->root, entry->offset,
1321 &entry->offset_index, 0);
1322 BUG_ON(ret);
1323
1324 if (!node || entry == last)
1325 break;
1326
1327 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1328 }
1329
1330 cluster->max_size = max_extent;
1331 got_it:
1332 ret = 0;
1333 atomic_inc(&block_group->count);
1334 list_add_tail(&cluster->block_group_list, &block_group->cluster_list);
1335 cluster->block_group = block_group;
1336 out:
1337 spin_unlock(&cluster->lock);
1338 spin_unlock(&block_group->tree_lock);
1339
1340 return ret;
1341 }
1342
1343 /*
1344 * simple code to zero out a cluster
1345 */
1346 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
1347 {
1348 spin_lock_init(&cluster->lock);
1349 spin_lock_init(&cluster->refill_lock);
1350 cluster->root.rb_node = NULL;
1351 cluster->max_size = 0;
1352 cluster->points_to_bitmap = false;
1353 INIT_LIST_HEAD(&cluster->block_group_list);
1354 cluster->block_group = NULL;
1355 }
1356
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