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/delay.h>
20 #include <linux/kthread.h>
21 #include <linux/pagemap.h>
22
23 #include "ctree.h"
24 #include "disk-io.h"
25 #include "free-space-cache.h"
26 #include "inode-map.h"
27 #include "transaction.h"
28
caching_kthread(void * data)29 static int caching_kthread(void *data)
30 {
31 struct btrfs_root *root = data;
32 struct btrfs_fs_info *fs_info = root->fs_info;
33 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
34 struct btrfs_key key;
35 struct btrfs_path *path;
36 struct extent_buffer *leaf;
37 u64 last = (u64)-1;
38 int slot;
39 int ret;
40
41 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
42 return 0;
43
44 path = btrfs_alloc_path();
45 if (!path)
46 return -ENOMEM;
47
48 /* Since the commit root is read-only, we can safely skip locking. */
49 path->skip_locking = 1;
50 path->search_commit_root = 1;
51 path->reada = 2;
52
53 key.objectid = BTRFS_FIRST_FREE_OBJECTID;
54 key.offset = 0;
55 key.type = BTRFS_INODE_ITEM_KEY;
56 again:
57 /* need to make sure the commit_root doesn't disappear */
58 mutex_lock(&root->fs_commit_mutex);
59
60 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
61 if (ret < 0)
62 goto out;
63
64 while (1) {
65 if (btrfs_fs_closing(fs_info))
66 goto out;
67
68 leaf = path->nodes[0];
69 slot = path->slots[0];
70 if (slot >= btrfs_header_nritems(leaf)) {
71 ret = btrfs_next_leaf(root, path);
72 if (ret < 0)
73 goto out;
74 else if (ret > 0)
75 break;
76
77 if (need_resched() ||
78 btrfs_transaction_in_commit(fs_info)) {
79 leaf = path->nodes[0];
80
81 if (btrfs_header_nritems(leaf) == 0) {
82 WARN_ON(1);
83 break;
84 }
85
86 /*
87 * Save the key so we can advances forward
88 * in the next search.
89 */
90 btrfs_item_key_to_cpu(leaf, &key, 0);
91 btrfs_release_path(path);
92 root->cache_progress = last;
93 mutex_unlock(&root->fs_commit_mutex);
94 schedule_timeout(1);
95 goto again;
96 } else
97 continue;
98 }
99
100 btrfs_item_key_to_cpu(leaf, &key, slot);
101
102 if (key.type != BTRFS_INODE_ITEM_KEY)
103 goto next;
104
105 if (key.objectid >= root->highest_objectid)
106 break;
107
108 if (last != (u64)-1 && last + 1 != key.objectid) {
109 __btrfs_add_free_space(ctl, last + 1,
110 key.objectid - last - 1);
111 wake_up(&root->cache_wait);
112 }
113
114 last = key.objectid;
115 next:
116 path->slots[0]++;
117 }
118
119 if (last < root->highest_objectid - 1) {
120 __btrfs_add_free_space(ctl, last + 1,
121 root->highest_objectid - last - 1);
122 }
123
124 spin_lock(&root->cache_lock);
125 root->cached = BTRFS_CACHE_FINISHED;
126 spin_unlock(&root->cache_lock);
127
128 root->cache_progress = (u64)-1;
129 btrfs_unpin_free_ino(root);
130 out:
131 wake_up(&root->cache_wait);
132 mutex_unlock(&root->fs_commit_mutex);
133
134 btrfs_free_path(path);
135
136 return ret;
137 }
138
start_caching(struct btrfs_root * root)139 static void start_caching(struct btrfs_root *root)
140 {
141 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
142 struct task_struct *tsk;
143 int ret;
144 u64 objectid;
145
146 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
147 return;
148
149 spin_lock(&root->cache_lock);
150 if (root->cached != BTRFS_CACHE_NO) {
151 spin_unlock(&root->cache_lock);
152 return;
153 }
154
155 root->cached = BTRFS_CACHE_STARTED;
156 spin_unlock(&root->cache_lock);
157
158 ret = load_free_ino_cache(root->fs_info, root);
159 if (ret == 1) {
160 spin_lock(&root->cache_lock);
161 root->cached = BTRFS_CACHE_FINISHED;
162 spin_unlock(&root->cache_lock);
163 return;
164 }
165
166 /*
167 * It can be quite time-consuming to fill the cache by searching
168 * through the extent tree, and this can keep ino allocation path
169 * waiting. Therefore at start we quickly find out the highest
170 * inode number and we know we can use inode numbers which fall in
171 * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
172 */
173 ret = btrfs_find_free_objectid(root, &objectid);
174 if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
175 __btrfs_add_free_space(ctl, objectid,
176 BTRFS_LAST_FREE_OBJECTID - objectid + 1);
177 }
178
179 tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
180 root->root_key.objectid);
181 BUG_ON(IS_ERR(tsk)); /* -ENOMEM */
182 }
183
btrfs_find_free_ino(struct btrfs_root * root,u64 * objectid)184 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
185 {
186 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
187 return btrfs_find_free_objectid(root, objectid);
188
189 again:
190 *objectid = btrfs_find_ino_for_alloc(root);
191
192 if (*objectid != 0)
193 return 0;
194
195 start_caching(root);
196
197 wait_event(root->cache_wait,
198 root->cached == BTRFS_CACHE_FINISHED ||
199 root->free_ino_ctl->free_space > 0);
200
201 if (root->cached == BTRFS_CACHE_FINISHED &&
202 root->free_ino_ctl->free_space == 0)
203 return -ENOSPC;
204 else
205 goto again;
206 }
207
btrfs_return_ino(struct btrfs_root * root,u64 objectid)208 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
209 {
210 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
211 struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
212
213 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
214 return;
215
216 again:
217 if (root->cached == BTRFS_CACHE_FINISHED) {
218 __btrfs_add_free_space(ctl, objectid, 1);
219 } else {
220 /*
221 * If we are in the process of caching free ino chunks,
222 * to avoid adding the same inode number to the free_ino
223 * tree twice due to cross transaction, we'll leave it
224 * in the pinned tree until a transaction is committed
225 * or the caching work is done.
226 */
227
228 mutex_lock(&root->fs_commit_mutex);
229 spin_lock(&root->cache_lock);
230 if (root->cached == BTRFS_CACHE_FINISHED) {
231 spin_unlock(&root->cache_lock);
232 mutex_unlock(&root->fs_commit_mutex);
233 goto again;
234 }
235 spin_unlock(&root->cache_lock);
236
237 start_caching(root);
238
239 if (objectid <= root->cache_progress ||
240 objectid > root->highest_objectid)
241 __btrfs_add_free_space(ctl, objectid, 1);
242 else
243 __btrfs_add_free_space(pinned, objectid, 1);
244
245 mutex_unlock(&root->fs_commit_mutex);
246 }
247 }
248
249 /*
250 * When a transaction is committed, we'll move those inode numbers which
251 * are smaller than root->cache_progress from pinned tree to free_ino tree,
252 * and others will just be dropped, because the commit root we were
253 * searching has changed.
254 *
255 * Must be called with root->fs_commit_mutex held
256 */
btrfs_unpin_free_ino(struct btrfs_root * root)257 void btrfs_unpin_free_ino(struct btrfs_root *root)
258 {
259 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
260 struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
261 struct btrfs_free_space *info;
262 struct rb_node *n;
263 u64 count;
264
265 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
266 return;
267
268 while (1) {
269 n = rb_first(rbroot);
270 if (!n)
271 break;
272
273 info = rb_entry(n, struct btrfs_free_space, offset_index);
274 BUG_ON(info->bitmap); /* Logic error */
275
276 if (info->offset > root->cache_progress)
277 goto free;
278 else if (info->offset + info->bytes > root->cache_progress)
279 count = root->cache_progress - info->offset + 1;
280 else
281 count = info->bytes;
282
283 __btrfs_add_free_space(ctl, info->offset, count);
284 free:
285 rb_erase(&info->offset_index, rbroot);
286 kfree(info);
287 }
288 }
289
290 #define INIT_THRESHOLD (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
291 #define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
292
293 /*
294 * The goal is to keep the memory used by the free_ino tree won't
295 * exceed the memory if we use bitmaps only.
296 */
recalculate_thresholds(struct btrfs_free_space_ctl * ctl)297 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
298 {
299 struct btrfs_free_space *info;
300 struct rb_node *n;
301 int max_ino;
302 int max_bitmaps;
303
304 n = rb_last(&ctl->free_space_offset);
305 if (!n) {
306 ctl->extents_thresh = INIT_THRESHOLD;
307 return;
308 }
309 info = rb_entry(n, struct btrfs_free_space, offset_index);
310
311 /*
312 * Find the maximum inode number in the filesystem. Note we
313 * ignore the fact that this can be a bitmap, because we are
314 * not doing precise calculation.
315 */
316 max_ino = info->bytes - 1;
317
318 max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
319 if (max_bitmaps <= ctl->total_bitmaps) {
320 ctl->extents_thresh = 0;
321 return;
322 }
323
324 ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
325 PAGE_CACHE_SIZE / sizeof(*info);
326 }
327
328 /*
329 * We don't fall back to bitmap, if we are below the extents threshold
330 * or this chunk of inode numbers is a big one.
331 */
use_bitmap(struct btrfs_free_space_ctl * ctl,struct btrfs_free_space * info)332 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
333 struct btrfs_free_space *info)
334 {
335 if (ctl->free_extents < ctl->extents_thresh ||
336 info->bytes > INODES_PER_BITMAP / 10)
337 return false;
338
339 return true;
340 }
341
342 static struct btrfs_free_space_op free_ino_op = {
343 .recalc_thresholds = recalculate_thresholds,
344 .use_bitmap = use_bitmap,
345 };
346
pinned_recalc_thresholds(struct btrfs_free_space_ctl * ctl)347 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
348 {
349 }
350
pinned_use_bitmap(struct btrfs_free_space_ctl * ctl,struct btrfs_free_space * info)351 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
352 struct btrfs_free_space *info)
353 {
354 /*
355 * We always use extents for two reasons:
356 *
357 * - The pinned tree is only used during the process of caching
358 * work.
359 * - Make code simpler. See btrfs_unpin_free_ino().
360 */
361 return false;
362 }
363
364 static struct btrfs_free_space_op pinned_free_ino_op = {
365 .recalc_thresholds = pinned_recalc_thresholds,
366 .use_bitmap = pinned_use_bitmap,
367 };
368
btrfs_init_free_ino_ctl(struct btrfs_root * root)369 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
370 {
371 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
372 struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
373
374 spin_lock_init(&ctl->tree_lock);
375 ctl->unit = 1;
376 ctl->start = 0;
377 ctl->private = NULL;
378 ctl->op = &free_ino_op;
379
380 /*
381 * Initially we allow to use 16K of ram to cache chunks of
382 * inode numbers before we resort to bitmaps. This is somewhat
383 * arbitrary, but it will be adjusted in runtime.
384 */
385 ctl->extents_thresh = INIT_THRESHOLD;
386
387 spin_lock_init(&pinned->tree_lock);
388 pinned->unit = 1;
389 pinned->start = 0;
390 pinned->private = NULL;
391 pinned->extents_thresh = 0;
392 pinned->op = &pinned_free_ino_op;
393 }
394
btrfs_save_ino_cache(struct btrfs_root * root,struct btrfs_trans_handle * trans)395 int btrfs_save_ino_cache(struct btrfs_root *root,
396 struct btrfs_trans_handle *trans)
397 {
398 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
399 struct btrfs_path *path;
400 struct inode *inode;
401 struct btrfs_block_rsv *rsv;
402 u64 num_bytes;
403 u64 alloc_hint = 0;
404 int ret;
405 int prealloc;
406 bool retry = false;
407
408 /* only fs tree and subvol/snap needs ino cache */
409 if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
410 (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
411 root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
412 return 0;
413
414 /* Don't save inode cache if we are deleting this root */
415 if (btrfs_root_refs(&root->root_item) == 0 &&
416 root != root->fs_info->tree_root)
417 return 0;
418
419 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
420 return 0;
421
422 path = btrfs_alloc_path();
423 if (!path)
424 return -ENOMEM;
425
426 rsv = trans->block_rsv;
427 trans->block_rsv = &root->fs_info->trans_block_rsv;
428
429 num_bytes = trans->bytes_reserved;
430 /*
431 * 1 item for inode item insertion if need
432 * 3 items for inode item update (in the worst case)
433 * 1 item for free space object
434 * 3 items for pre-allocation
435 */
436 trans->bytes_reserved = btrfs_calc_trans_metadata_size(root, 8);
437 ret = btrfs_block_rsv_add_noflush(root, trans->block_rsv,
438 trans->bytes_reserved);
439 if (ret)
440 goto out;
441 trace_btrfs_space_reservation(root->fs_info, "ino_cache",
442 trans->transid, trans->bytes_reserved, 1);
443 again:
444 inode = lookup_free_ino_inode(root, path);
445 if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
446 ret = PTR_ERR(inode);
447 goto out_release;
448 }
449
450 if (IS_ERR(inode)) {
451 BUG_ON(retry); /* Logic error */
452 retry = true;
453
454 ret = create_free_ino_inode(root, trans, path);
455 if (ret)
456 goto out_release;
457 goto again;
458 }
459
460 BTRFS_I(inode)->generation = 0;
461 ret = btrfs_update_inode(trans, root, inode);
462 if (ret) {
463 btrfs_abort_transaction(trans, root, ret);
464 goto out_put;
465 }
466
467 if (i_size_read(inode) > 0) {
468 ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
469 if (ret) {
470 btrfs_abort_transaction(trans, root, ret);
471 goto out_put;
472 }
473 }
474
475 spin_lock(&root->cache_lock);
476 if (root->cached != BTRFS_CACHE_FINISHED) {
477 ret = -1;
478 spin_unlock(&root->cache_lock);
479 goto out_put;
480 }
481 spin_unlock(&root->cache_lock);
482
483 spin_lock(&ctl->tree_lock);
484 prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
485 prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
486 prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
487 spin_unlock(&ctl->tree_lock);
488
489 /* Just to make sure we have enough space */
490 prealloc += 8 * PAGE_CACHE_SIZE;
491
492 ret = btrfs_delalloc_reserve_space(inode, prealloc);
493 if (ret)
494 goto out_put;
495
496 ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
497 prealloc, prealloc, &alloc_hint);
498 if (ret) {
499 btrfs_delalloc_release_space(inode, prealloc);
500 goto out_put;
501 }
502 btrfs_free_reserved_data_space(inode, prealloc);
503
504 ret = btrfs_write_out_ino_cache(root, trans, path);
505 out_put:
506 iput(inode);
507 out_release:
508 trace_btrfs_space_reservation(root->fs_info, "ino_cache",
509 trans->transid, trans->bytes_reserved, 0);
510 btrfs_block_rsv_release(root, trans->block_rsv, trans->bytes_reserved);
511 out:
512 trans->block_rsv = rsv;
513 trans->bytes_reserved = num_bytes;
514
515 btrfs_free_path(path);
516 return ret;
517 }
518
btrfs_find_highest_objectid(struct btrfs_root * root,u64 * objectid)519 static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
520 {
521 struct btrfs_path *path;
522 int ret;
523 struct extent_buffer *l;
524 struct btrfs_key search_key;
525 struct btrfs_key found_key;
526 int slot;
527
528 path = btrfs_alloc_path();
529 if (!path)
530 return -ENOMEM;
531
532 search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
533 search_key.type = -1;
534 search_key.offset = (u64)-1;
535 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
536 if (ret < 0)
537 goto error;
538 BUG_ON(ret == 0); /* Corruption */
539 if (path->slots[0] > 0) {
540 slot = path->slots[0] - 1;
541 l = path->nodes[0];
542 btrfs_item_key_to_cpu(l, &found_key, slot);
543 *objectid = max_t(u64, found_key.objectid,
544 BTRFS_FIRST_FREE_OBJECTID - 1);
545 } else {
546 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
547 }
548 ret = 0;
549 error:
550 btrfs_free_path(path);
551 return ret;
552 }
553
btrfs_find_free_objectid(struct btrfs_root * root,u64 * objectid)554 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
555 {
556 int ret;
557 mutex_lock(&root->objectid_mutex);
558
559 if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
560 ret = btrfs_find_highest_objectid(root,
561 &root->highest_objectid);
562 if (ret)
563 goto out;
564 }
565
566 if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
567 ret = -ENOSPC;
568 goto out;
569 }
570
571 *objectid = ++root->highest_objectid;
572 ret = 0;
573 out:
574 mutex_unlock(&root->objectid_mutex);
575 return ret;
576 }
577