summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/free-space-cache.c
blob: 69b023ff6f72bf32600be301596cba723adc1708 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
/*
 * Copyright (C) 2008 Red Hat.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/sched.h>
#include "ctree.h"

static int tree_insert_offset(struct rb_root *root, u64 offset,
			      struct rb_node *node)
{
	struct rb_node **p = &root->rb_node;
	struct rb_node *parent = NULL;
	struct btrfs_free_space *info;

	while (*p) {
		parent = *p;
		info = rb_entry(parent, struct btrfs_free_space, offset_index);

		if (offset < info->offset)
			p = &(*p)->rb_left;
		else if (offset > info->offset)
			p = &(*p)->rb_right;
		else
			return -EEXIST;
	}

	rb_link_node(node, parent, p);
	rb_insert_color(node, root);

	return 0;
}

static int tree_insert_bytes(struct rb_root *root, u64 bytes,
			     struct rb_node *node)
{
	struct rb_node **p = &root->rb_node;
	struct rb_node *parent = NULL;
	struct btrfs_free_space *info;

	while (*p) {
		parent = *p;
		info = rb_entry(parent, struct btrfs_free_space, bytes_index);

		if (bytes < info->bytes)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	rb_link_node(node, parent, p);
	rb_insert_color(node, root);

	return 0;
}

/*
 * searches the tree for the given offset.
 *
 * fuzzy == 1: this is used for allocations where we are given a hint of where
 * to look for free space.  Because the hint may not be completely on an offset
 * mark, or the hint may no longer point to free space we need to fudge our
 * results a bit.  So we look for free space starting at or after offset with at
 * least bytes size.  We prefer to find as close to the given offset as we can.
 * Also if the offset is within a free space range, then we will return the free
 * space that contains the given offset, which means we can return a free space
 * chunk with an offset before the provided offset.
 *
 * fuzzy == 0: this is just a normal tree search.  Give us the free space that
 * starts at the given offset which is at least bytes size, and if its not there
 * return NULL.
 */
static struct btrfs_free_space *tree_search_offset(struct rb_root *root,
						   u64 offset, u64 bytes,
						   int fuzzy)
{
	struct rb_node *n = root->rb_node;
	struct btrfs_free_space *entry, *ret = NULL;

	while (n) {
		entry = rb_entry(n, struct btrfs_free_space, offset_index);

		if (offset < entry->offset) {
			if (fuzzy &&
			    (!ret || entry->offset < ret->offset) &&
			    (bytes <= entry->bytes))
				ret = entry;
			n = n->rb_left;
		} else if (offset > entry->offset) {
			if (fuzzy &&
			    (entry->offset + entry->bytes - 1) >= offset &&
			    bytes <= entry->bytes) {
				ret = entry;
				break;
			}
			n = n->rb_right;
		} else {
			if (bytes > entry->bytes) {
				n = n->rb_right;
				continue;
			}
			ret = entry;
			break;
		}
	}

	return ret;
}

/*
 * return a chunk at least bytes size, as close to offset that we can get.
 */
static struct btrfs_free_space *tree_search_bytes(struct rb_root *root,
						  u64 offset, u64 bytes)
{
	struct rb_node *n = root->rb_node;
	struct btrfs_free_space *entry, *ret = NULL;

	while (n) {
		entry = rb_entry(n, struct btrfs_free_space, bytes_index);

		if (bytes < entry->bytes) {
			/*
			 * We prefer to get a hole size as close to the size we
			 * are asking for so we don't take small slivers out of
			 * huge holes, but we also want to get as close to the
			 * offset as possible so we don't have a whole lot of
			 * fragmentation.
			 */
			if (offset <= entry->offset) {
				if (!ret)
					ret = entry;
				else if (entry->bytes < ret->bytes)
					ret = entry;
				else if (entry->offset < ret->offset)
					ret = entry;
			}
			n = n->rb_left;
		} else if (bytes > entry->bytes) {
			n = n->rb_right;
		} else {
			/*
			 * Ok we may have multiple chunks of the wanted size,
			 * so we don't want to take the first one we find, we
			 * want to take the one closest to our given offset, so
			 * keep searching just in case theres a better match.
			 */
			n = n->rb_right;
			if (offset > entry->offset)
				continue;
			else if (!ret || entry->offset < ret->offset)
				ret = entry;
		}
	}

	return ret;
}

static void unlink_free_space(struct btrfs_block_group_cache *block_group,
			      struct btrfs_free_space *info)
{
	rb_erase(&info->offset_index, &block_group->free_space_offset);
	rb_erase(&info->bytes_index, &block_group->free_space_bytes);
}

static int link_free_space(struct btrfs_block_group_cache *block_group,
			   struct btrfs_free_space *info)
{
	int ret = 0;


	ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
				 &info->offset_index);
	if (ret)
		return ret;

	ret = tree_insert_bytes(&block_group->free_space_bytes, info->bytes,
				&info->bytes_index);
	if (ret)
		return ret;

	return ret;
}

static int __btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
				  u64 offset, u64 bytes)
{
	struct btrfs_free_space *right_info;
	struct btrfs_free_space *left_info;
	struct btrfs_free_space *info = NULL;
	int ret = 0;

	/*
	 * first we want to see if there is free space adjacent to the range we
	 * are adding, if there is remove that struct and add a new one to
	 * cover the entire range
	 */
	right_info = tree_search_offset(&block_group->free_space_offset,
					offset+bytes, 0, 0);
	left_info = tree_search_offset(&block_group->free_space_offset,
				       offset-1, 0, 1);

	if (right_info) {
		unlink_free_space(block_group, right_info);
		info = right_info;
		info->offset = offset;
		info->bytes += bytes;
	}

	if (left_info && left_info->offset + left_info->bytes == offset) {
		unlink_free_space(block_group, left_info);

		if (info) {
			info->offset = left_info->offset;
			info->bytes += left_info->bytes;
			kfree(left_info);
		} else {
			info = left_info;
			info->bytes += bytes;
		}
	}

	if (info) {
		ret = link_free_space(block_group, info);
		if (ret)
			kfree(info);
		goto out;
	}

	info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
	if (!info)
		return -ENOMEM;

	info->offset = offset;
	info->bytes = bytes;

	ret = link_free_space(block_group, info);
	if (ret)
		kfree(info);
out:
	if (ret) {
		printk(KERN_ERR "btrfs: unable to add free space :%d\n", ret);
		if (ret == -EEXIST)
			BUG();
	}

	return ret;
}

static int
__btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
			  u64 offset, u64 bytes)
{
	struct btrfs_free_space *info;
	int ret = 0;

	BUG_ON(!block_group->cached);
	info = tree_search_offset(&block_group->free_space_offset, offset, 0,
				  1);

	if (info && info->offset == offset) {
		if (info->bytes < bytes) {
			printk(KERN_ERR "Found free space at %llu, size %llu,"
			       "trying to use %llu\n",
			       (unsigned long long)info->offset,
			       (unsigned long long)info->bytes,
			       (unsigned long long)bytes);
			WARN_ON(1);
			ret = -EINVAL;
			goto out;
		}
		unlink_free_space(block_group, info);

		if (info->bytes == bytes) {
			kfree(info);
			goto out;
		}

		info->offset += bytes;
		info->bytes -= bytes;

		ret = link_free_space(block_group, info);
		BUG_ON(ret);
	} else if (info && info->offset < offset &&
		   info->offset + info->bytes >= offset + bytes) {
		u64 old_start = info->offset;
		/*
		 * we're freeing space in the middle of the info,
		 * this can happen during tree log replay
		 *
		 * first unlink the old info and then
		 * insert it again after the hole we're creating
		 */
		unlink_free_space(block_group, info);
		if (offset + bytes < info->offset + info->bytes) {
			u64 old_end = info->offset + info->bytes;

			info->offset = offset + bytes;
			info->bytes = old_end - info->offset;
			ret = link_free_space(block_group, info);
			BUG_ON(ret);
		} else {
			/* the hole we're creating ends at the end
			 * of the info struct, just free the info
			 */
			kfree(info);
		}

		/* step two, insert a new info struct to cover anything
		 * before the hole
		 */
		ret = __btrfs_add_free_space(block_group, old_start,
					     offset - old_start);
		BUG_ON(ret);
	} else {
		if (!info) {
			printk(KERN_ERR "couldn't find space %llu to free\n",
			       (unsigned long long)offset);
			printk(KERN_ERR "cached is %d, offset %llu bytes %llu\n",
			       block_group->cached, block_group->key.objectid,
			       block_group->key.offset);
			btrfs_dump_free_space(block_group, bytes);
		} else if (info) {
			printk(KERN_ERR "hmm, found offset=%llu bytes=%llu, "
			       "but wanted offset=%llu bytes=%llu\n",
			       info->offset, info->bytes, offset, bytes);
		}
		WARN_ON(1);
	}
out:
	return ret;
}

int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
			 u64 offset, u64 bytes)
{
	int ret;

	mutex_lock(&block_group->alloc_mutex);
	ret = __btrfs_add_free_space(block_group, offset, bytes);
	mutex_unlock(&block_group->alloc_mutex);

	return ret;
}

int btrfs_add_free_space_lock(struct btrfs_block_group_cache *block_group,
			      u64 offset, u64 bytes)
{
	int ret;

	ret = __btrfs_add_free_space(block_group, offset, bytes);

	return ret;
}

int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
			    u64 offset, u64 bytes)
{
	int ret = 0;

	mutex_lock(&block_group->alloc_mutex);
	ret = __btrfs_remove_free_space(block_group, offset, bytes);
	mutex_unlock(&block_group->alloc_mutex);

	return ret;
}

int btrfs_remove_free_space_lock(struct btrfs_block_group_cache *block_group,
				 u64 offset, u64 bytes)
{
	int ret;

	ret = __btrfs_remove_free_space(block_group, offset, bytes);

	return ret;
}

void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
			   u64 bytes)
{
	struct btrfs_free_space *info;
	struct rb_node *n;
	int count = 0;

	for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
		info = rb_entry(n, struct btrfs_free_space, offset_index);
		if (info->bytes >= bytes)
			count++;
		printk(KERN_ERR "entry offset %llu, bytes %llu\n", info->offset,
		       info->bytes);
	}
	printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
	       "\n", count);
}

u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
{
	struct btrfs_free_space *info;
	struct rb_node *n;
	u64 ret = 0;

	for (n = rb_first(&block_group->free_space_offset); n;
	     n = rb_next(n)) {
		info = rb_entry(n, struct btrfs_free_space, offset_index);
		ret += info->bytes;
	}

	return ret;
}

void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
{
	struct btrfs_free_space *info;
	struct rb_node *node;

	mutex_lock(&block_group->alloc_mutex);
	while ((node = rb_last(&block_group->free_space_bytes)) != NULL) {
		info = rb_entry(node, struct btrfs_free_space, bytes_index);
		unlink_free_space(block_group, info);
		kfree(info);
		if (need_resched()) {
			mutex_unlock(&block_group->alloc_mutex);
			cond_resched();
			mutex_lock(&block_group->alloc_mutex);
		}
	}
	mutex_unlock(&block_group->alloc_mutex);
}

#if 0
static struct btrfs_free_space *btrfs_find_free_space_offset(struct
						      btrfs_block_group_cache
						      *block_group, u64 offset,
						      u64 bytes)
{
	struct btrfs_free_space *ret;

	mutex_lock(&block_group->alloc_mutex);
	ret = tree_search_offset(&block_group->free_space_offset, offset,
				 bytes, 0);
	mutex_unlock(&block_group->alloc_mutex);

	return ret;
}

static struct btrfs_free_space *btrfs_find_free_space_bytes(struct
						     btrfs_block_group_cache
						     *block_group, u64 offset,
						     u64 bytes)
{
	struct btrfs_free_space *ret;

	mutex_lock(&block_group->alloc_mutex);

	ret = tree_search_bytes(&block_group->free_space_bytes, offset, bytes);
	mutex_unlock(&block_group->alloc_mutex);

	return ret;
}
#endif

struct btrfs_free_space *btrfs_find_free_space(struct btrfs_block_group_cache
					       *block_group, u64 offset,
					       u64 bytes)
{
	struct btrfs_free_space *ret = NULL;

	ret = tree_search_offset(&block_group->free_space_offset, offset,
				 bytes, 1);
	if (!ret)
		ret = tree_search_bytes(&block_group->free_space_bytes,
					offset, bytes);

	return ret;
}
OpenPOWER on IntegriCloud