1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2007 Oracle. All rights reserved.
4 */
5
6 #include <linux/kthread.h>
7 #include <linux/pagemap.h>
8
9 #include "ctree.h"
10 #include "disk-io.h"
11 #include "free-space-cache.h"
12 #include "inode-map.h"
13 #include "transaction.h"
14
fail_caching_thread(struct btrfs_root * root)15 static void fail_caching_thread(struct btrfs_root *root)
16 {
17 struct btrfs_fs_info *fs_info = root->fs_info;
18
19 btrfs_warn(fs_info, "failed to start inode caching task");
20 btrfs_clear_pending_and_info(fs_info, INODE_MAP_CACHE,
21 "disabling inode map caching");
22 spin_lock(&root->ino_cache_lock);
23 root->ino_cache_state = BTRFS_CACHE_ERROR;
24 spin_unlock(&root->ino_cache_lock);
25 wake_up(&root->ino_cache_wait);
26 }
27
caching_kthread(void * data)28 static int caching_kthread(void *data)
29 {
30 struct btrfs_root *root = data;
31 struct btrfs_fs_info *fs_info = root->fs_info;
32 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
33 struct btrfs_key key;
34 struct btrfs_path *path;
35 struct extent_buffer *leaf;
36 u64 last = (u64)-1;
37 int slot;
38 int ret;
39
40 if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
41 return 0;
42
43 path = btrfs_alloc_path();
44 if (!path) {
45 fail_caching_thread(root);
46 return -ENOMEM;
47 }
48
49 /* Since the commit root is read-only, we can safely skip locking. */
50 path->skip_locking = 1;
51 path->search_commit_root = 1;
52 path->reada = READA_FORWARD;
53
54 key.objectid = BTRFS_FIRST_FREE_OBJECTID;
55 key.offset = 0;
56 key.type = BTRFS_INODE_ITEM_KEY;
57 again:
58 /* need to make sure the commit_root doesn't disappear */
59 down_read(&fs_info->commit_root_sem);
60
61 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
62 if (ret < 0)
63 goto out;
64
65 while (1) {
66 if (btrfs_fs_closing(fs_info))
67 goto out;
68
69 leaf = path->nodes[0];
70 slot = path->slots[0];
71 if (slot >= btrfs_header_nritems(leaf)) {
72 ret = btrfs_next_leaf(root, path);
73 if (ret < 0)
74 goto out;
75 else if (ret > 0)
76 break;
77
78 if (need_resched() ||
79 btrfs_transaction_in_commit(fs_info)) {
80 leaf = path->nodes[0];
81
82 if (WARN_ON(btrfs_header_nritems(leaf) == 0))
83 break;
84
85 /*
86 * Save the key so we can advances forward
87 * in the next search.
88 */
89 btrfs_item_key_to_cpu(leaf, &key, 0);
90 btrfs_release_path(path);
91 root->ino_cache_progress = last;
92 up_read(&fs_info->commit_root_sem);
93 schedule_timeout(1);
94 goto again;
95 } else
96 continue;
97 }
98
99 btrfs_item_key_to_cpu(leaf, &key, slot);
100
101 if (key.type != BTRFS_INODE_ITEM_KEY)
102 goto next;
103
104 if (key.objectid >= root->highest_objectid)
105 break;
106
107 if (last != (u64)-1 && last + 1 != key.objectid) {
108 __btrfs_add_free_space(fs_info, ctl, last + 1,
109 key.objectid - last - 1);
110 wake_up(&root->ino_cache_wait);
111 }
112
113 last = key.objectid;
114 next:
115 path->slots[0]++;
116 }
117
118 if (last < root->highest_objectid - 1) {
119 __btrfs_add_free_space(fs_info, ctl, last + 1,
120 root->highest_objectid - last - 1);
121 }
122
123 spin_lock(&root->ino_cache_lock);
124 root->ino_cache_state = BTRFS_CACHE_FINISHED;
125 spin_unlock(&root->ino_cache_lock);
126
127 root->ino_cache_progress = (u64)-1;
128 btrfs_unpin_free_ino(root);
129 out:
130 wake_up(&root->ino_cache_wait);
131 up_read(&fs_info->commit_root_sem);
132
133 btrfs_free_path(path);
134
135 return ret;
136 }
137
start_caching(struct btrfs_root * root)138 static void start_caching(struct btrfs_root *root)
139 {
140 struct btrfs_fs_info *fs_info = root->fs_info;
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(fs_info, INODE_MAP_CACHE))
147 return;
148
149 spin_lock(&root->ino_cache_lock);
150 if (root->ino_cache_state != BTRFS_CACHE_NO) {
151 spin_unlock(&root->ino_cache_lock);
152 return;
153 }
154
155 root->ino_cache_state = BTRFS_CACHE_STARTED;
156 spin_unlock(&root->ino_cache_lock);
157
158 ret = load_free_ino_cache(fs_info, root);
159 if (ret == 1) {
160 spin_lock(&root->ino_cache_lock);
161 root->ino_cache_state = BTRFS_CACHE_FINISHED;
162 spin_unlock(&root->ino_cache_lock);
163 wake_up(&root->ino_cache_wait);
164 return;
165 }
166
167 /*
168 * It can be quite time-consuming to fill the cache by searching
169 * through the extent tree, and this can keep ino allocation path
170 * waiting. Therefore at start we quickly find out the highest
171 * inode number and we know we can use inode numbers which fall in
172 * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
173 */
174 ret = btrfs_find_free_objectid(root, &objectid);
175 if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
176 __btrfs_add_free_space(fs_info, ctl, objectid,
177 BTRFS_LAST_FREE_OBJECTID - objectid + 1);
178 }
179
180 tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
181 root->root_key.objectid);
182 if (IS_ERR(tsk))
183 fail_caching_thread(root);
184 }
185
btrfs_find_free_ino(struct btrfs_root * root,u64 * objectid)186 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
187 {
188 if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
189 return btrfs_find_free_objectid(root, objectid);
190
191 again:
192 *objectid = btrfs_find_ino_for_alloc(root);
193
194 if (*objectid != 0)
195 return 0;
196
197 start_caching(root);
198
199 wait_event(root->ino_cache_wait,
200 root->ino_cache_state == BTRFS_CACHE_FINISHED ||
201 root->ino_cache_state == BTRFS_CACHE_ERROR ||
202 root->free_ino_ctl->free_space > 0);
203
204 if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
205 root->free_ino_ctl->free_space == 0)
206 return -ENOSPC;
207 else if (root->ino_cache_state == BTRFS_CACHE_ERROR)
208 return btrfs_find_free_objectid(root, objectid);
209 else
210 goto again;
211 }
212
btrfs_return_ino(struct btrfs_root * root,u64 objectid)213 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
214 {
215 struct btrfs_fs_info *fs_info = root->fs_info;
216 struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
217
218 if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
219 return;
220 again:
221 if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
222 __btrfs_add_free_space(fs_info, pinned, objectid, 1);
223 } else {
224 down_write(&fs_info->commit_root_sem);
225 spin_lock(&root->ino_cache_lock);
226 if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
227 spin_unlock(&root->ino_cache_lock);
228 up_write(&fs_info->commit_root_sem);
229 goto again;
230 }
231 spin_unlock(&root->ino_cache_lock);
232
233 start_caching(root);
234
235 __btrfs_add_free_space(fs_info, pinned, objectid, 1);
236
237 up_write(&fs_info->commit_root_sem);
238 }
239 }
240
241 /*
242 * When a transaction is committed, we'll move those inode numbers which are
243 * smaller than root->ino_cache_progress from pinned tree to free_ino tree, and
244 * others will just be dropped, because the commit root we were searching has
245 * changed.
246 *
247 * Must be called with root->fs_info->commit_root_sem held
248 */
btrfs_unpin_free_ino(struct btrfs_root * root)249 void btrfs_unpin_free_ino(struct btrfs_root *root)
250 {
251 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
252 struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
253 spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
254 struct btrfs_free_space *info;
255 struct rb_node *n;
256 u64 count;
257
258 if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
259 return;
260
261 while (1) {
262 spin_lock(rbroot_lock);
263 n = rb_first(rbroot);
264 if (!n) {
265 spin_unlock(rbroot_lock);
266 break;
267 }
268
269 info = rb_entry(n, struct btrfs_free_space, offset_index);
270 BUG_ON(info->bitmap); /* Logic error */
271
272 if (info->offset > root->ino_cache_progress)
273 count = 0;
274 else
275 count = min(root->ino_cache_progress - info->offset + 1,
276 info->bytes);
277
278 rb_erase(&info->offset_index, rbroot);
279 spin_unlock(rbroot_lock);
280 if (count)
281 __btrfs_add_free_space(root->fs_info, ctl,
282 info->offset, count);
283 kmem_cache_free(btrfs_free_space_cachep, info);
284 }
285 }
286
287 #define INIT_THRESHOLD ((SZ_32K / 2) / sizeof(struct btrfs_free_space))
288 #define INODES_PER_BITMAP (PAGE_SIZE * 8)
289
290 /*
291 * The goal is to keep the memory used by the free_ino tree won't
292 * exceed the memory if we use bitmaps only.
293 */
recalculate_thresholds(struct btrfs_free_space_ctl * ctl)294 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
295 {
296 struct btrfs_free_space *info;
297 struct rb_node *n;
298 int max_ino;
299 int max_bitmaps;
300
301 n = rb_last(&ctl->free_space_offset);
302 if (!n) {
303 ctl->extents_thresh = INIT_THRESHOLD;
304 return;
305 }
306 info = rb_entry(n, struct btrfs_free_space, offset_index);
307
308 /*
309 * Find the maximum inode number in the filesystem. Note we
310 * ignore the fact that this can be a bitmap, because we are
311 * not doing precise calculation.
312 */
313 max_ino = info->bytes - 1;
314
315 max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
316 if (max_bitmaps <= ctl->total_bitmaps) {
317 ctl->extents_thresh = 0;
318 return;
319 }
320
321 ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
322 PAGE_SIZE / sizeof(*info);
323 }
324
325 /*
326 * We don't fall back to bitmap, if we are below the extents threshold
327 * or this chunk of inode numbers is a big one.
328 */
use_bitmap(struct btrfs_free_space_ctl * ctl,struct btrfs_free_space * info)329 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
330 struct btrfs_free_space *info)
331 {
332 if (ctl->free_extents < ctl->extents_thresh ||
333 info->bytes > INODES_PER_BITMAP / 10)
334 return false;
335
336 return true;
337 }
338
339 static const struct btrfs_free_space_op free_ino_op = {
340 .recalc_thresholds = recalculate_thresholds,
341 .use_bitmap = use_bitmap,
342 };
343
pinned_recalc_thresholds(struct btrfs_free_space_ctl * ctl)344 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
345 {
346 }
347
pinned_use_bitmap(struct btrfs_free_space_ctl * ctl,struct btrfs_free_space * info)348 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
349 struct btrfs_free_space *info)
350 {
351 /*
352 * We always use extents for two reasons:
353 *
354 * - The pinned tree is only used during the process of caching
355 * work.
356 * - Make code simpler. See btrfs_unpin_free_ino().
357 */
358 return false;
359 }
360
361 static const struct btrfs_free_space_op pinned_free_ino_op = {
362 .recalc_thresholds = pinned_recalc_thresholds,
363 .use_bitmap = pinned_use_bitmap,
364 };
365
btrfs_init_free_ino_ctl(struct btrfs_root * root)366 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
367 {
368 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
369 struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
370
371 spin_lock_init(&ctl->tree_lock);
372 ctl->unit = 1;
373 ctl->start = 0;
374 ctl->private = NULL;
375 ctl->op = &free_ino_op;
376 INIT_LIST_HEAD(&ctl->trimming_ranges);
377 mutex_init(&ctl->cache_writeout_mutex);
378
379 /*
380 * Initially we allow to use 16K of ram to cache chunks of
381 * inode numbers before we resort to bitmaps. This is somewhat
382 * arbitrary, but it will be adjusted in runtime.
383 */
384 ctl->extents_thresh = INIT_THRESHOLD;
385
386 spin_lock_init(&pinned->tree_lock);
387 pinned->unit = 1;
388 pinned->start = 0;
389 pinned->private = NULL;
390 pinned->extents_thresh = 0;
391 pinned->op = &pinned_free_ino_op;
392 }
393
btrfs_save_ino_cache(struct btrfs_root * root,struct btrfs_trans_handle * trans)394 int btrfs_save_ino_cache(struct btrfs_root *root,
395 struct btrfs_trans_handle *trans)
396 {
397 struct btrfs_fs_info *fs_info = root->fs_info;
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 struct extent_changeset *data_reserved = NULL;
403 u64 num_bytes;
404 u64 alloc_hint = 0;
405 int ret;
406 int prealloc;
407 bool retry = false;
408
409 /* only fs tree and subvol/snap needs ino cache */
410 if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
411 (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
412 root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
413 return 0;
414
415 /* Don't save inode cache if we are deleting this root */
416 if (btrfs_root_refs(&root->root_item) == 0)
417 return 0;
418
419 if (!btrfs_test_opt(fs_info, 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 = &fs_info->trans_block_rsv;
428
429 num_bytes = trans->bytes_reserved;
430 /*
431 * 1 item for inode item insertion if need
432 * 4 items for inode item update (in the worst case)
433 * 1 items for slack space if we need do truncation
434 * 1 item for free space object
435 * 3 items for pre-allocation
436 */
437 trans->bytes_reserved = btrfs_calc_trans_metadata_size(fs_info, 10);
438 ret = btrfs_block_rsv_add(root, trans->block_rsv,
439 trans->bytes_reserved,
440 BTRFS_RESERVE_NO_FLUSH);
441 if (ret)
442 goto out;
443 trace_btrfs_space_reservation(fs_info, "ino_cache", trans->transid,
444 trans->bytes_reserved, 1);
445 again:
446 inode = lookup_free_ino_inode(root, path);
447 if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
448 ret = PTR_ERR(inode);
449 goto out_release;
450 }
451
452 if (IS_ERR(inode)) {
453 BUG_ON(retry); /* Logic error */
454 retry = true;
455
456 ret = create_free_ino_inode(root, trans, path);
457 if (ret)
458 goto out_release;
459 goto again;
460 }
461
462 BTRFS_I(inode)->generation = 0;
463 ret = btrfs_update_inode(trans, root, inode);
464 if (ret) {
465 btrfs_abort_transaction(trans, ret);
466 goto out_put;
467 }
468
469 if (i_size_read(inode) > 0) {
470 ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
471 if (ret) {
472 if (ret != -ENOSPC)
473 btrfs_abort_transaction(trans, ret);
474 goto out_put;
475 }
476 }
477
478 spin_lock(&root->ino_cache_lock);
479 if (root->ino_cache_state != BTRFS_CACHE_FINISHED) {
480 ret = -1;
481 spin_unlock(&root->ino_cache_lock);
482 goto out_put;
483 }
484 spin_unlock(&root->ino_cache_lock);
485
486 spin_lock(&ctl->tree_lock);
487 prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
488 prealloc = ALIGN(prealloc, PAGE_SIZE);
489 prealloc += ctl->total_bitmaps * PAGE_SIZE;
490 spin_unlock(&ctl->tree_lock);
491
492 /* Just to make sure we have enough space */
493 prealloc += 8 * PAGE_SIZE;
494
495 ret = btrfs_delalloc_reserve_space(inode, &data_reserved, 0, prealloc);
496 if (ret)
497 goto out_put;
498
499 ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
500 prealloc, prealloc, &alloc_hint);
501 if (ret) {
502 btrfs_delalloc_release_extents(BTRFS_I(inode), prealloc);
503 btrfs_delalloc_release_metadata(BTRFS_I(inode), prealloc, true);
504 goto out_put;
505 }
506
507 ret = btrfs_write_out_ino_cache(root, trans, path, inode);
508 btrfs_delalloc_release_extents(BTRFS_I(inode), prealloc);
509 out_put:
510 iput(inode);
511 out_release:
512 trace_btrfs_space_reservation(fs_info, "ino_cache", trans->transid,
513 trans->bytes_reserved, 0);
514 btrfs_block_rsv_release(fs_info, trans->block_rsv,
515 trans->bytes_reserved);
516 out:
517 trans->block_rsv = rsv;
518 trans->bytes_reserved = num_bytes;
519
520 btrfs_free_path(path);
521 extent_changeset_free(data_reserved);
522 return ret;
523 }
524
btrfs_find_highest_objectid(struct btrfs_root * root,u64 * objectid)525 int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
526 {
527 struct btrfs_path *path;
528 int ret;
529 struct extent_buffer *l;
530 struct btrfs_key search_key;
531 struct btrfs_key found_key;
532 int slot;
533
534 path = btrfs_alloc_path();
535 if (!path)
536 return -ENOMEM;
537
538 search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
539 search_key.type = -1;
540 search_key.offset = (u64)-1;
541 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
542 if (ret < 0)
543 goto error;
544 BUG_ON(ret == 0); /* Corruption */
545 if (path->slots[0] > 0) {
546 slot = path->slots[0] - 1;
547 l = path->nodes[0];
548 btrfs_item_key_to_cpu(l, &found_key, slot);
549 *objectid = max_t(u64, found_key.objectid,
550 BTRFS_FIRST_FREE_OBJECTID - 1);
551 } else {
552 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
553 }
554 ret = 0;
555 error:
556 btrfs_free_path(path);
557 return ret;
558 }
559
btrfs_find_free_objectid(struct btrfs_root * root,u64 * objectid)560 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
561 {
562 int ret;
563 mutex_lock(&root->objectid_mutex);
564
565 if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
566 btrfs_warn(root->fs_info,
567 "the objectid of root %llu reaches its highest value",
568 root->root_key.objectid);
569 ret = -ENOSPC;
570 goto out;
571 }
572
573 *objectid = ++root->highest_objectid;
574 ret = 0;
575 out:
576 mutex_unlock(&root->objectid_mutex);
577 return ret;
578 }
579