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0f9dd46c JB |
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/sched.h> | |
20 | #include "ctree.h" | |
fa9c0d79 CM |
21 | #include "free-space-cache.h" |
22 | #include "transaction.h" | |
23 | ||
24 | struct btrfs_free_space { | |
25 | struct rb_node bytes_index; | |
26 | struct rb_node offset_index; | |
27 | u64 offset; | |
28 | u64 bytes; | |
29 | }; | |
0f9dd46c JB |
30 | |
31 | static int tree_insert_offset(struct rb_root *root, u64 offset, | |
32 | struct rb_node *node) | |
33 | { | |
34 | struct rb_node **p = &root->rb_node; | |
35 | struct rb_node *parent = NULL; | |
36 | struct btrfs_free_space *info; | |
37 | ||
38 | while (*p) { | |
39 | parent = *p; | |
40 | info = rb_entry(parent, struct btrfs_free_space, offset_index); | |
41 | ||
42 | if (offset < info->offset) | |
43 | p = &(*p)->rb_left; | |
44 | else if (offset > info->offset) | |
45 | p = &(*p)->rb_right; | |
46 | else | |
47 | return -EEXIST; | |
48 | } | |
49 | ||
50 | rb_link_node(node, parent, p); | |
51 | rb_insert_color(node, root); | |
52 | ||
53 | return 0; | |
54 | } | |
55 | ||
56 | static int tree_insert_bytes(struct rb_root *root, u64 bytes, | |
57 | struct rb_node *node) | |
58 | { | |
59 | struct rb_node **p = &root->rb_node; | |
60 | struct rb_node *parent = NULL; | |
61 | struct btrfs_free_space *info; | |
62 | ||
63 | while (*p) { | |
64 | parent = *p; | |
65 | info = rb_entry(parent, struct btrfs_free_space, bytes_index); | |
66 | ||
67 | if (bytes < info->bytes) | |
68 | p = &(*p)->rb_left; | |
69 | else | |
70 | p = &(*p)->rb_right; | |
71 | } | |
72 | ||
73 | rb_link_node(node, parent, p); | |
74 | rb_insert_color(node, root); | |
75 | ||
76 | return 0; | |
77 | } | |
78 | ||
79 | /* | |
70cb0743 JB |
80 | * searches the tree for the given offset. |
81 | * | |
82 | * fuzzy == 1: this is used for allocations where we are given a hint of where | |
83 | * to look for free space. Because the hint may not be completely on an offset | |
84 | * mark, or the hint may no longer point to free space we need to fudge our | |
85 | * results a bit. So we look for free space starting at or after offset with at | |
86 | * least bytes size. We prefer to find as close to the given offset as we can. | |
87 | * Also if the offset is within a free space range, then we will return the free | |
88 | * space that contains the given offset, which means we can return a free space | |
89 | * chunk with an offset before the provided offset. | |
90 | * | |
91 | * fuzzy == 0: this is just a normal tree search. Give us the free space that | |
92 | * starts at the given offset which is at least bytes size, and if its not there | |
93 | * return NULL. | |
0f9dd46c JB |
94 | */ |
95 | static struct btrfs_free_space *tree_search_offset(struct rb_root *root, | |
96 | u64 offset, u64 bytes, | |
70cb0743 | 97 | int fuzzy) |
0f9dd46c JB |
98 | { |
99 | struct rb_node *n = root->rb_node; | |
100 | struct btrfs_free_space *entry, *ret = NULL; | |
101 | ||
102 | while (n) { | |
103 | entry = rb_entry(n, struct btrfs_free_space, offset_index); | |
104 | ||
105 | if (offset < entry->offset) { | |
70cb0743 | 106 | if (fuzzy && |
0f9dd46c JB |
107 | (!ret || entry->offset < ret->offset) && |
108 | (bytes <= entry->bytes)) | |
109 | ret = entry; | |
110 | n = n->rb_left; | |
111 | } else if (offset > entry->offset) { | |
70cb0743 JB |
112 | if (fuzzy && |
113 | (entry->offset + entry->bytes - 1) >= offset && | |
37d3cddd | 114 | bytes <= entry->bytes) { |
0f9dd46c JB |
115 | ret = entry; |
116 | break; | |
117 | } | |
118 | n = n->rb_right; | |
119 | } else { | |
120 | if (bytes > entry->bytes) { | |
121 | n = n->rb_right; | |
122 | continue; | |
123 | } | |
124 | ret = entry; | |
125 | break; | |
126 | } | |
127 | } | |
128 | ||
129 | return ret; | |
130 | } | |
131 | ||
132 | /* | |
133 | * return a chunk at least bytes size, as close to offset that we can get. | |
134 | */ | |
135 | static struct btrfs_free_space *tree_search_bytes(struct rb_root *root, | |
136 | u64 offset, u64 bytes) | |
137 | { | |
138 | struct rb_node *n = root->rb_node; | |
139 | struct btrfs_free_space *entry, *ret = NULL; | |
140 | ||
141 | while (n) { | |
142 | entry = rb_entry(n, struct btrfs_free_space, bytes_index); | |
143 | ||
144 | if (bytes < entry->bytes) { | |
145 | /* | |
146 | * We prefer to get a hole size as close to the size we | |
147 | * are asking for so we don't take small slivers out of | |
148 | * huge holes, but we also want to get as close to the | |
149 | * offset as possible so we don't have a whole lot of | |
150 | * fragmentation. | |
151 | */ | |
152 | if (offset <= entry->offset) { | |
153 | if (!ret) | |
154 | ret = entry; | |
155 | else if (entry->bytes < ret->bytes) | |
156 | ret = entry; | |
157 | else if (entry->offset < ret->offset) | |
158 | ret = entry; | |
159 | } | |
160 | n = n->rb_left; | |
161 | } else if (bytes > entry->bytes) { | |
162 | n = n->rb_right; | |
163 | } else { | |
164 | /* | |
165 | * Ok we may have multiple chunks of the wanted size, | |
166 | * so we don't want to take the first one we find, we | |
167 | * want to take the one closest to our given offset, so | |
168 | * keep searching just in case theres a better match. | |
169 | */ | |
170 | n = n->rb_right; | |
171 | if (offset > entry->offset) | |
172 | continue; | |
173 | else if (!ret || entry->offset < ret->offset) | |
174 | ret = entry; | |
175 | } | |
176 | } | |
177 | ||
178 | return ret; | |
179 | } | |
180 | ||
181 | static void unlink_free_space(struct btrfs_block_group_cache *block_group, | |
182 | struct btrfs_free_space *info) | |
183 | { | |
184 | rb_erase(&info->offset_index, &block_group->free_space_offset); | |
185 | rb_erase(&info->bytes_index, &block_group->free_space_bytes); | |
186 | } | |
187 | ||
188 | static int link_free_space(struct btrfs_block_group_cache *block_group, | |
189 | struct btrfs_free_space *info) | |
190 | { | |
191 | int ret = 0; | |
192 | ||
193 | ||
6226cb0a | 194 | BUG_ON(!info->bytes); |
0f9dd46c JB |
195 | ret = tree_insert_offset(&block_group->free_space_offset, info->offset, |
196 | &info->offset_index); | |
197 | if (ret) | |
198 | return ret; | |
199 | ||
200 | ret = tree_insert_bytes(&block_group->free_space_bytes, info->bytes, | |
201 | &info->bytes_index); | |
202 | if (ret) | |
203 | return ret; | |
204 | ||
205 | return ret; | |
206 | } | |
207 | ||
6226cb0a JB |
208 | int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, |
209 | u64 offset, u64 bytes) | |
0f9dd46c JB |
210 | { |
211 | struct btrfs_free_space *right_info; | |
212 | struct btrfs_free_space *left_info; | |
213 | struct btrfs_free_space *info = NULL; | |
0f9dd46c JB |
214 | int ret = 0; |
215 | ||
6226cb0a JB |
216 | info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS); |
217 | if (!info) | |
218 | return -ENOMEM; | |
219 | ||
220 | info->offset = offset; | |
221 | info->bytes = bytes; | |
222 | ||
223 | spin_lock(&block_group->tree_lock); | |
224 | ||
0f9dd46c JB |
225 | /* |
226 | * first we want to see if there is free space adjacent to the range we | |
227 | * are adding, if there is remove that struct and add a new one to | |
228 | * cover the entire range | |
229 | */ | |
0f9dd46c | 230 | right_info = tree_search_offset(&block_group->free_space_offset, |
70cb0743 | 231 | offset+bytes, 0, 0); |
0f9dd46c JB |
232 | left_info = tree_search_offset(&block_group->free_space_offset, |
233 | offset-1, 0, 1); | |
234 | ||
70cb0743 | 235 | if (right_info) { |
0f9dd46c | 236 | unlink_free_space(block_group, right_info); |
6226cb0a JB |
237 | info->bytes += right_info->bytes; |
238 | kfree(right_info); | |
0f9dd46c JB |
239 | } |
240 | ||
70cb0743 | 241 | if (left_info && left_info->offset + left_info->bytes == offset) { |
0f9dd46c | 242 | unlink_free_space(block_group, left_info); |
6226cb0a JB |
243 | info->offset = left_info->offset; |
244 | info->bytes += left_info->bytes; | |
245 | kfree(left_info); | |
0f9dd46c JB |
246 | } |
247 | ||
0f9dd46c JB |
248 | ret = link_free_space(block_group, info); |
249 | if (ret) | |
250 | kfree(info); | |
6226cb0a JB |
251 | |
252 | spin_unlock(&block_group->tree_lock); | |
253 | ||
0f9dd46c JB |
254 | if (ret) { |
255 | printk(KERN_ERR "btrfs: unable to add free space :%d\n", ret); | |
256 | if (ret == -EEXIST) | |
257 | BUG(); | |
258 | } | |
259 | ||
0f9dd46c JB |
260 | return ret; |
261 | } | |
262 | ||
6226cb0a JB |
263 | int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group, |
264 | u64 offset, u64 bytes) | |
0f9dd46c JB |
265 | { |
266 | struct btrfs_free_space *info; | |
267 | int ret = 0; | |
268 | ||
6226cb0a JB |
269 | spin_lock(&block_group->tree_lock); |
270 | ||
0f9dd46c JB |
271 | info = tree_search_offset(&block_group->free_space_offset, offset, 0, |
272 | 1); | |
0f9dd46c JB |
273 | if (info && info->offset == offset) { |
274 | if (info->bytes < bytes) { | |
d397712b CM |
275 | printk(KERN_ERR "Found free space at %llu, size %llu," |
276 | "trying to use %llu\n", | |
277 | (unsigned long long)info->offset, | |
278 | (unsigned long long)info->bytes, | |
279 | (unsigned long long)bytes); | |
0f9dd46c JB |
280 | WARN_ON(1); |
281 | ret = -EINVAL; | |
6226cb0a | 282 | spin_unlock(&block_group->tree_lock); |
0f9dd46c JB |
283 | goto out; |
284 | } | |
0f9dd46c JB |
285 | unlink_free_space(block_group, info); |
286 | ||
287 | if (info->bytes == bytes) { | |
288 | kfree(info); | |
6226cb0a | 289 | spin_unlock(&block_group->tree_lock); |
0f9dd46c JB |
290 | goto out; |
291 | } | |
292 | ||
293 | info->offset += bytes; | |
294 | info->bytes -= bytes; | |
295 | ||
296 | ret = link_free_space(block_group, info); | |
6226cb0a | 297 | spin_unlock(&block_group->tree_lock); |
0f9dd46c | 298 | BUG_ON(ret); |
9b49c9b9 CM |
299 | } else if (info && info->offset < offset && |
300 | info->offset + info->bytes >= offset + bytes) { | |
301 | u64 old_start = info->offset; | |
302 | /* | |
303 | * we're freeing space in the middle of the info, | |
304 | * this can happen during tree log replay | |
305 | * | |
306 | * first unlink the old info and then | |
307 | * insert it again after the hole we're creating | |
308 | */ | |
309 | unlink_free_space(block_group, info); | |
310 | if (offset + bytes < info->offset + info->bytes) { | |
311 | u64 old_end = info->offset + info->bytes; | |
312 | ||
313 | info->offset = offset + bytes; | |
314 | info->bytes = old_end - info->offset; | |
315 | ret = link_free_space(block_group, info); | |
316 | BUG_ON(ret); | |
317 | } else { | |
318 | /* the hole we're creating ends at the end | |
319 | * of the info struct, just free the info | |
320 | */ | |
321 | kfree(info); | |
322 | } | |
6226cb0a | 323 | spin_unlock(&block_group->tree_lock); |
9b49c9b9 CM |
324 | /* step two, insert a new info struct to cover anything |
325 | * before the hole | |
326 | */ | |
6226cb0a JB |
327 | ret = btrfs_add_free_space(block_group, old_start, |
328 | offset - old_start); | |
9b49c9b9 | 329 | BUG_ON(ret); |
0f9dd46c | 330 | } else { |
6226cb0a | 331 | spin_unlock(&block_group->tree_lock); |
70cb0743 JB |
332 | if (!info) { |
333 | printk(KERN_ERR "couldn't find space %llu to free\n", | |
334 | (unsigned long long)offset); | |
335 | printk(KERN_ERR "cached is %d, offset %llu bytes %llu\n", | |
336 | block_group->cached, block_group->key.objectid, | |
337 | block_group->key.offset); | |
338 | btrfs_dump_free_space(block_group, bytes); | |
339 | } else if (info) { | |
340 | printk(KERN_ERR "hmm, found offset=%llu bytes=%llu, " | |
341 | "but wanted offset=%llu bytes=%llu\n", | |
342 | info->offset, info->bytes, offset, bytes); | |
343 | } | |
0f9dd46c JB |
344 | WARN_ON(1); |
345 | } | |
346 | out: | |
25179201 JB |
347 | return ret; |
348 | } | |
349 | ||
0f9dd46c JB |
350 | void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group, |
351 | u64 bytes) | |
352 | { | |
353 | struct btrfs_free_space *info; | |
354 | struct rb_node *n; | |
355 | int count = 0; | |
356 | ||
357 | for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) { | |
358 | info = rb_entry(n, struct btrfs_free_space, offset_index); | |
359 | if (info->bytes >= bytes) | |
360 | count++; | |
70cb0743 JB |
361 | printk(KERN_ERR "entry offset %llu, bytes %llu\n", info->offset, |
362 | info->bytes); | |
0f9dd46c JB |
363 | } |
364 | printk(KERN_INFO "%d blocks of free space at or bigger than bytes is" | |
365 | "\n", count); | |
366 | } | |
367 | ||
368 | u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group) | |
369 | { | |
370 | struct btrfs_free_space *info; | |
371 | struct rb_node *n; | |
372 | u64 ret = 0; | |
373 | ||
374 | for (n = rb_first(&block_group->free_space_offset); n; | |
375 | n = rb_next(n)) { | |
376 | info = rb_entry(n, struct btrfs_free_space, offset_index); | |
377 | ret += info->bytes; | |
378 | } | |
379 | ||
380 | return ret; | |
381 | } | |
382 | ||
fa9c0d79 CM |
383 | /* |
384 | * for a given cluster, put all of its extents back into the free | |
385 | * space cache. If the block group passed doesn't match the block group | |
386 | * pointed to by the cluster, someone else raced in and freed the | |
387 | * cluster already. In that case, we just return without changing anything | |
388 | */ | |
389 | static int | |
390 | __btrfs_return_cluster_to_free_space( | |
391 | struct btrfs_block_group_cache *block_group, | |
392 | struct btrfs_free_cluster *cluster) | |
393 | { | |
394 | struct btrfs_free_space *entry; | |
395 | struct rb_node *node; | |
396 | ||
397 | spin_lock(&cluster->lock); | |
398 | if (cluster->block_group != block_group) | |
399 | goto out; | |
400 | ||
401 | cluster->window_start = 0; | |
402 | node = rb_first(&cluster->root); | |
403 | while(node) { | |
404 | entry = rb_entry(node, struct btrfs_free_space, offset_index); | |
405 | node = rb_next(&entry->offset_index); | |
406 | rb_erase(&entry->offset_index, &cluster->root); | |
407 | link_free_space(block_group, entry); | |
408 | } | |
409 | list_del_init(&cluster->block_group_list); | |
410 | ||
411 | btrfs_put_block_group(cluster->block_group); | |
412 | cluster->block_group = NULL; | |
413 | cluster->root.rb_node = NULL; | |
414 | out: | |
415 | spin_unlock(&cluster->lock); | |
416 | return 0; | |
417 | } | |
418 | ||
0f9dd46c JB |
419 | void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group) |
420 | { | |
421 | struct btrfs_free_space *info; | |
422 | struct rb_node *node; | |
fa9c0d79 CM |
423 | struct btrfs_free_cluster *cluster; |
424 | struct btrfs_free_cluster *safe; | |
0f9dd46c | 425 | |
6226cb0a | 426 | spin_lock(&block_group->tree_lock); |
fa9c0d79 CM |
427 | |
428 | list_for_each_entry_safe(cluster, safe, &block_group->cluster_list, | |
429 | block_group_list) { | |
430 | ||
431 | WARN_ON(cluster->block_group != block_group); | |
432 | __btrfs_return_cluster_to_free_space(block_group, cluster); | |
433 | } | |
434 | ||
0f9dd46c JB |
435 | while ((node = rb_last(&block_group->free_space_bytes)) != NULL) { |
436 | info = rb_entry(node, struct btrfs_free_space, bytes_index); | |
437 | unlink_free_space(block_group, info); | |
438 | kfree(info); | |
439 | if (need_resched()) { | |
6226cb0a | 440 | spin_unlock(&block_group->tree_lock); |
0f9dd46c | 441 | cond_resched(); |
6226cb0a | 442 | spin_lock(&block_group->tree_lock); |
0f9dd46c JB |
443 | } |
444 | } | |
6226cb0a | 445 | spin_unlock(&block_group->tree_lock); |
0f9dd46c JB |
446 | } |
447 | ||
6226cb0a JB |
448 | u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group, |
449 | u64 offset, u64 bytes, u64 empty_size) | |
0f9dd46c | 450 | { |
6226cb0a JB |
451 | struct btrfs_free_space *entry = NULL; |
452 | u64 ret = 0; | |
0f9dd46c | 453 | |
6226cb0a JB |
454 | spin_lock(&block_group->tree_lock); |
455 | entry = tree_search_offset(&block_group->free_space_offset, offset, | |
456 | bytes + empty_size, 1); | |
457 | if (!entry) | |
458 | entry = tree_search_bytes(&block_group->free_space_bytes, | |
459 | offset, bytes + empty_size); | |
460 | if (entry) { | |
461 | unlink_free_space(block_group, entry); | |
462 | ret = entry->offset; | |
463 | entry->offset += bytes; | |
464 | entry->bytes -= bytes; | |
465 | ||
466 | if (!entry->bytes) | |
467 | kfree(entry); | |
468 | else | |
469 | link_free_space(block_group, entry); | |
470 | } | |
471 | spin_unlock(&block_group->tree_lock); | |
0f9dd46c | 472 | |
0f9dd46c JB |
473 | return ret; |
474 | } | |
fa9c0d79 CM |
475 | |
476 | /* | |
477 | * given a cluster, put all of its extents back into the free space | |
478 | * cache. If a block group is passed, this function will only free | |
479 | * a cluster that belongs to the passed block group. | |
480 | * | |
481 | * Otherwise, it'll get a reference on the block group pointed to by the | |
482 | * cluster and remove the cluster from it. | |
483 | */ | |
484 | int btrfs_return_cluster_to_free_space( | |
485 | struct btrfs_block_group_cache *block_group, | |
486 | struct btrfs_free_cluster *cluster) | |
487 | { | |
488 | int ret; | |
489 | ||
490 | /* first, get a safe pointer to the block group */ | |
491 | spin_lock(&cluster->lock); | |
492 | if (!block_group) { | |
493 | block_group = cluster->block_group; | |
494 | if (!block_group) { | |
495 | spin_unlock(&cluster->lock); | |
496 | return 0; | |
497 | } | |
498 | } else if (cluster->block_group != block_group) { | |
499 | /* someone else has already freed it don't redo their work */ | |
500 | spin_unlock(&cluster->lock); | |
501 | return 0; | |
502 | } | |
503 | atomic_inc(&block_group->count); | |
504 | spin_unlock(&cluster->lock); | |
505 | ||
506 | /* now return any extents the cluster had on it */ | |
507 | spin_lock(&block_group->tree_lock); | |
508 | ret = __btrfs_return_cluster_to_free_space(block_group, cluster); | |
509 | spin_unlock(&block_group->tree_lock); | |
510 | ||
511 | /* finally drop our ref */ | |
512 | btrfs_put_block_group(block_group); | |
513 | return ret; | |
514 | } | |
515 | ||
516 | /* | |
517 | * given a cluster, try to allocate 'bytes' from it, returns 0 | |
518 | * if it couldn't find anything suitably large, or a logical disk offset | |
519 | * if things worked out | |
520 | */ | |
521 | u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group, | |
522 | struct btrfs_free_cluster *cluster, u64 bytes, | |
523 | u64 min_start) | |
524 | { | |
525 | struct btrfs_free_space *entry = NULL; | |
526 | struct rb_node *node; | |
527 | u64 ret = 0; | |
528 | ||
529 | spin_lock(&cluster->lock); | |
530 | if (bytes > cluster->max_size) | |
531 | goto out; | |
532 | ||
533 | if (cluster->block_group != block_group) | |
534 | goto out; | |
535 | ||
536 | node = rb_first(&cluster->root); | |
537 | if (!node) | |
538 | goto out; | |
539 | ||
540 | entry = rb_entry(node, struct btrfs_free_space, offset_index); | |
541 | ||
542 | while(1) { | |
543 | if (entry->bytes < bytes || entry->offset < min_start) { | |
544 | struct rb_node *node; | |
545 | ||
546 | node = rb_next(&entry->offset_index); | |
547 | if (!node) | |
548 | break; | |
549 | entry = rb_entry(node, struct btrfs_free_space, | |
550 | offset_index); | |
551 | continue; | |
552 | } | |
553 | ret = entry->offset; | |
554 | ||
555 | entry->offset += bytes; | |
556 | entry->bytes -= bytes; | |
557 | ||
558 | if (entry->bytes == 0) { | |
559 | rb_erase(&entry->offset_index, &cluster->root); | |
560 | kfree(entry); | |
561 | } | |
562 | break; | |
563 | } | |
564 | out: | |
565 | spin_unlock(&cluster->lock); | |
566 | return ret; | |
567 | } | |
568 | ||
569 | /* | |
570 | * here we try to find a cluster of blocks in a block group. The goal | |
571 | * is to find at least bytes free and up to empty_size + bytes free. | |
572 | * We might not find them all in one contiguous area. | |
573 | * | |
574 | * returns zero and sets up cluster if things worked out, otherwise | |
575 | * it returns -enospc | |
576 | */ | |
577 | int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, | |
578 | struct btrfs_block_group_cache *block_group, | |
579 | struct btrfs_free_cluster *cluster, | |
580 | u64 offset, u64 bytes, u64 empty_size) | |
581 | { | |
582 | struct btrfs_free_space *entry = NULL; | |
583 | struct rb_node *node; | |
584 | struct btrfs_free_space *next; | |
585 | struct btrfs_free_space *last; | |
586 | u64 min_bytes; | |
587 | u64 window_start; | |
588 | u64 window_free; | |
589 | u64 max_extent = 0; | |
590 | int total_retries = 0; | |
591 | int ret; | |
592 | ||
593 | /* for metadata, allow allocates with more holes */ | |
594 | if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) { | |
595 | /* | |
596 | * we want to do larger allocations when we are | |
597 | * flushing out the delayed refs, it helps prevent | |
598 | * making more work as we go along. | |
599 | */ | |
600 | if (trans->transaction->delayed_refs.flushing) | |
601 | min_bytes = max(bytes, (bytes + empty_size) >> 1); | |
602 | else | |
603 | min_bytes = max(bytes, (bytes + empty_size) >> 4); | |
604 | } else | |
605 | min_bytes = max(bytes, (bytes + empty_size) >> 2); | |
606 | ||
607 | spin_lock(&block_group->tree_lock); | |
608 | spin_lock(&cluster->lock); | |
609 | ||
610 | /* someone already found a cluster, hooray */ | |
611 | if (cluster->block_group) { | |
612 | ret = 0; | |
613 | goto out; | |
614 | } | |
615 | again: | |
616 | min_bytes = min(min_bytes, bytes + empty_size); | |
617 | entry = tree_search_bytes(&block_group->free_space_bytes, | |
618 | offset, min_bytes); | |
619 | if (!entry) { | |
620 | ret = -ENOSPC; | |
621 | goto out; | |
622 | } | |
623 | window_start = entry->offset; | |
624 | window_free = entry->bytes; | |
625 | last = entry; | |
626 | max_extent = entry->bytes; | |
627 | ||
628 | while(1) { | |
629 | /* out window is just right, lets fill it */ | |
630 | if (window_free >= bytes + empty_size) | |
631 | break; | |
632 | ||
633 | node = rb_next(&last->offset_index); | |
634 | if (!node) { | |
635 | ret = -ENOSPC; | |
636 | goto out; | |
637 | } | |
638 | next = rb_entry(node, struct btrfs_free_space, offset_index); | |
639 | ||
640 | /* | |
641 | * we haven't filled the empty size and the window is | |
642 | * very large. reset and try again | |
643 | */ | |
644 | if (next->offset - window_start > (bytes + empty_size) * 2) { | |
645 | entry = next; | |
646 | window_start = entry->offset; | |
647 | window_free = entry->bytes; | |
648 | last = entry; | |
649 | max_extent = 0; | |
650 | total_retries++; | |
651 | if (total_retries % 256 == 0) { | |
652 | if (min_bytes >= (bytes + empty_size)) { | |
653 | ret = -ENOSPC; | |
654 | goto out; | |
655 | } | |
656 | /* | |
657 | * grow our allocation a bit, we're not having | |
658 | * much luck | |
659 | */ | |
660 | min_bytes *= 2; | |
661 | goto again; | |
662 | } | |
663 | } else { | |
664 | last = next; | |
665 | window_free += next->bytes; | |
666 | if (entry->bytes > max_extent) | |
667 | max_extent = entry->bytes; | |
668 | } | |
669 | } | |
670 | ||
671 | cluster->window_start = entry->offset; | |
672 | ||
673 | /* | |
674 | * now we've found our entries, pull them out of the free space | |
675 | * cache and put them into the cluster rbtree | |
676 | * | |
677 | * The cluster includes an rbtree, but only uses the offset index | |
678 | * of each free space cache entry. | |
679 | */ | |
680 | while(1) { | |
681 | node = rb_next(&entry->offset_index); | |
682 | unlink_free_space(block_group, entry); | |
683 | ret = tree_insert_offset(&cluster->root, entry->offset, | |
684 | &entry->offset_index); | |
685 | BUG_ON(ret); | |
686 | ||
687 | if (!node || entry == last) | |
688 | break; | |
689 | ||
690 | entry = rb_entry(node, struct btrfs_free_space, offset_index); | |
691 | } | |
692 | ret = 0; | |
693 | cluster->max_size = max_extent; | |
694 | atomic_inc(&block_group->count); | |
695 | list_add_tail(&cluster->block_group_list, &block_group->cluster_list); | |
696 | cluster->block_group = block_group; | |
697 | out: | |
698 | spin_unlock(&cluster->lock); | |
699 | spin_unlock(&block_group->tree_lock); | |
700 | ||
701 | return ret; | |
702 | } | |
703 | ||
704 | /* | |
705 | * simple code to zero out a cluster | |
706 | */ | |
707 | void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster) | |
708 | { | |
709 | spin_lock_init(&cluster->lock); | |
710 | spin_lock_init(&cluster->refill_lock); | |
711 | cluster->root.rb_node = NULL; | |
712 | cluster->max_size = 0; | |
713 | INIT_LIST_HEAD(&cluster->block_group_list); | |
714 | cluster->block_group = NULL; | |
715 | } | |
716 |