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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
29static 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;
56again:
57 /* need to make sure the commit_root doesn't disappear */
58 down_read(&fs_info->commit_root_sem);
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 (WARN_ON(btrfs_header_nritems(leaf) == 0))
82 break;
83
84 /*
85 * Save the key so we can advances forward
86 * in the next search.
87 */
88 btrfs_item_key_to_cpu(leaf, &key, 0);
89 btrfs_release_path(path);
90 root->cache_progress = last;
91 up_read(&fs_info->commit_root_sem);
92 schedule_timeout(1);
93 goto again;
94 } else
95 continue;
96 }
97
98 btrfs_item_key_to_cpu(leaf, &key, slot);
99
100 if (key.type != BTRFS_INODE_ITEM_KEY)
101 goto next;
102
103 if (key.objectid >= root->highest_objectid)
104 break;
105
106 if (last != (u64)-1 && last + 1 != key.objectid) {
107 __btrfs_add_free_space(ctl, last + 1,
108 key.objectid - last - 1);
109 wake_up(&root->cache_wait);
110 }
111
112 last = key.objectid;
113next:
114 path->slots[0]++;
115 }
116
117 if (last < root->highest_objectid - 1) {
118 __btrfs_add_free_space(ctl, last + 1,
119 root->highest_objectid - last - 1);
120 }
121
122 spin_lock(&root->cache_lock);
123 root->cached = BTRFS_CACHE_FINISHED;
124 spin_unlock(&root->cache_lock);
125
126 root->cache_progress = (u64)-1;
127 btrfs_unpin_free_ino(root);
128out:
129 wake_up(&root->cache_wait);
130 up_read(&fs_info->commit_root_sem);
131
132 btrfs_free_path(path);
133
134 return ret;
135}
136
137static void start_caching(struct btrfs_root *root)
138{
139 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
140 struct task_struct *tsk;
141 int ret;
142 u64 objectid;
143
144 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
145 return;
146
147 spin_lock(&root->cache_lock);
148 if (root->cached != BTRFS_CACHE_NO) {
149 spin_unlock(&root->cache_lock);
150 return;
151 }
152
153 root->cached = BTRFS_CACHE_STARTED;
154 spin_unlock(&root->cache_lock);
155
156 ret = load_free_ino_cache(root->fs_info, root);
157 if (ret == 1) {
158 spin_lock(&root->cache_lock);
159 root->cached = BTRFS_CACHE_FINISHED;
160 spin_unlock(&root->cache_lock);
161 return;
162 }
163
164 /*
165 * It can be quite time-consuming to fill the cache by searching
166 * through the extent tree, and this can keep ino allocation path
167 * waiting. Therefore at start we quickly find out the highest
168 * inode number and we know we can use inode numbers which fall in
169 * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
170 */
171 ret = btrfs_find_free_objectid(root, &objectid);
172 if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
173 __btrfs_add_free_space(ctl, objectid,
174 BTRFS_LAST_FREE_OBJECTID - objectid + 1);
175 }
176
177 tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
178 root->root_key.objectid);
179 if (IS_ERR(tsk)) {
180 btrfs_warn(root->fs_info, "failed to start inode caching task");
181 btrfs_clear_and_info(root, CHANGE_INODE_CACHE,
182 "disabling inode map caching");
183 }
184}
185
186int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
187{
188 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
189 return btrfs_find_free_objectid(root, objectid);
190
191again:
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->cache_wait,
200 root->cached == BTRFS_CACHE_FINISHED ||
201 root->free_ino_ctl->free_space > 0);
202
203 if (root->cached == BTRFS_CACHE_FINISHED &&
204 root->free_ino_ctl->free_space == 0)
205 return -ENOSPC;
206 else
207 goto again;
208}
209
210void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
211{
212 struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
213
214 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
215 return;
216again:
217 if (root->cached == BTRFS_CACHE_FINISHED) {
218 __btrfs_add_free_space(pinned, objectid, 1);
219 } else {
220 down_write(&root->fs_info->commit_root_sem);
221 spin_lock(&root->cache_lock);
222 if (root->cached == BTRFS_CACHE_FINISHED) {
223 spin_unlock(&root->cache_lock);
224 up_write(&root->fs_info->commit_root_sem);
225 goto again;
226 }
227 spin_unlock(&root->cache_lock);
228
229 start_caching(root);
230
231 __btrfs_add_free_space(pinned, objectid, 1);
232
233 up_write(&root->fs_info->commit_root_sem);
234 }
235}
236
237/*
238 * When a transaction is committed, we'll move those inode numbers which
239 * are smaller than root->cache_progress from pinned tree to free_ino tree,
240 * and others will just be dropped, because the commit root we were
241 * searching has changed.
242 *
243 * Must be called with root->fs_info->commit_root_sem held
244 */
245void btrfs_unpin_free_ino(struct btrfs_root *root)
246{
247 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
248 struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
249 struct btrfs_free_space *info;
250 struct rb_node *n;
251 u64 count;
252
253 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
254 return;
255
256 while (1) {
257 n = rb_first(rbroot);
258 if (!n)
259 break;
260
261 info = rb_entry(n, struct btrfs_free_space, offset_index);
262 BUG_ON(info->bitmap); /* Logic error */
263
264 if (info->offset > root->cache_progress)
265 goto free;
266 else if (info->offset + info->bytes > root->cache_progress)
267 count = root->cache_progress - info->offset + 1;
268 else
269 count = info->bytes;
270
271 __btrfs_add_free_space(ctl, info->offset, count);
272free:
273 rb_erase(&info->offset_index, rbroot);
274 kfree(info);
275 }
276}
277
278#define INIT_THRESHOLD (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
279#define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
280
281/*
282 * The goal is to keep the memory used by the free_ino tree won't
283 * exceed the memory if we use bitmaps only.
284 */
285static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
286{
287 struct btrfs_free_space *info;
288 struct rb_node *n;
289 int max_ino;
290 int max_bitmaps;
291
292 n = rb_last(&ctl->free_space_offset);
293 if (!n) {
294 ctl->extents_thresh = INIT_THRESHOLD;
295 return;
296 }
297 info = rb_entry(n, struct btrfs_free_space, offset_index);
298
299 /*
300 * Find the maximum inode number in the filesystem. Note we
301 * ignore the fact that this can be a bitmap, because we are
302 * not doing precise calculation.
303 */
304 max_ino = info->bytes - 1;
305
306 max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
307 if (max_bitmaps <= ctl->total_bitmaps) {
308 ctl->extents_thresh = 0;
309 return;
310 }
311
312 ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
313 PAGE_CACHE_SIZE / sizeof(*info);
314}
315
316/*
317 * We don't fall back to bitmap, if we are below the extents threshold
318 * or this chunk of inode numbers is a big one.
319 */
320static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
321 struct btrfs_free_space *info)
322{
323 if (ctl->free_extents < ctl->extents_thresh ||
324 info->bytes > INODES_PER_BITMAP / 10)
325 return false;
326
327 return true;
328}
329
330static struct btrfs_free_space_op free_ino_op = {
331 .recalc_thresholds = recalculate_thresholds,
332 .use_bitmap = use_bitmap,
333};
334
335static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
336{
337}
338
339static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
340 struct btrfs_free_space *info)
341{
342 /*
343 * We always use extents for two reasons:
344 *
345 * - The pinned tree is only used during the process of caching
346 * work.
347 * - Make code simpler. See btrfs_unpin_free_ino().
348 */
349 return false;
350}
351
352static struct btrfs_free_space_op pinned_free_ino_op = {
353 .recalc_thresholds = pinned_recalc_thresholds,
354 .use_bitmap = pinned_use_bitmap,
355};
356
357void btrfs_init_free_ino_ctl(struct btrfs_root *root)
358{
359 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
360 struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
361
362 spin_lock_init(&ctl->tree_lock);
363 ctl->unit = 1;
364 ctl->start = 0;
365 ctl->private = NULL;
366 ctl->op = &free_ino_op;
367
368 /*
369 * Initially we allow to use 16K of ram to cache chunks of
370 * inode numbers before we resort to bitmaps. This is somewhat
371 * arbitrary, but it will be adjusted in runtime.
372 */
373 ctl->extents_thresh = INIT_THRESHOLD;
374
375 spin_lock_init(&pinned->tree_lock);
376 pinned->unit = 1;
377 pinned->start = 0;
378 pinned->private = NULL;
379 pinned->extents_thresh = 0;
380 pinned->op = &pinned_free_ino_op;
381}
382
383int btrfs_save_ino_cache(struct btrfs_root *root,
384 struct btrfs_trans_handle *trans)
385{
386 struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
387 struct btrfs_path *path;
388 struct inode *inode;
389 struct btrfs_block_rsv *rsv;
390 u64 num_bytes;
391 u64 alloc_hint = 0;
392 int ret;
393 int prealloc;
394 bool retry = false;
395
396 /* only fs tree and subvol/snap needs ino cache */
397 if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
398 (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
399 root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
400 return 0;
401
402 /* Don't save inode cache if we are deleting this root */
403 if (btrfs_root_refs(&root->root_item) == 0)
404 return 0;
405
406 if (!btrfs_test_opt(root, INODE_MAP_CACHE))
407 return 0;
408
409 path = btrfs_alloc_path();
410 if (!path)
411 return -ENOMEM;
412
413 rsv = trans->block_rsv;
414 trans->block_rsv = &root->fs_info->trans_block_rsv;
415
416 num_bytes = trans->bytes_reserved;
417 /*
418 * 1 item for inode item insertion if need
419 * 4 items for inode item update (in the worst case)
420 * 1 items for slack space if we need do truncation
421 * 1 item for free space object
422 * 3 items for pre-allocation
423 */
424 trans->bytes_reserved = btrfs_calc_trans_metadata_size(root, 10);
425 ret = btrfs_block_rsv_add(root, trans->block_rsv,
426 trans->bytes_reserved,
427 BTRFS_RESERVE_NO_FLUSH);
428 if (ret)
429 goto out;
430 trace_btrfs_space_reservation(root->fs_info, "ino_cache",
431 trans->transid, trans->bytes_reserved, 1);
432again:
433 inode = lookup_free_ino_inode(root, path);
434 if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
435 ret = PTR_ERR(inode);
436 goto out_release;
437 }
438
439 if (IS_ERR(inode)) {
440 BUG_ON(retry); /* Logic error */
441 retry = true;
442
443 ret = create_free_ino_inode(root, trans, path);
444 if (ret)
445 goto out_release;
446 goto again;
447 }
448
449 BTRFS_I(inode)->generation = 0;
450 ret = btrfs_update_inode(trans, root, inode);
451 if (ret) {
452 btrfs_abort_transaction(trans, root, ret);
453 goto out_put;
454 }
455
456 if (i_size_read(inode) > 0) {
457 ret = btrfs_truncate_free_space_cache(root, trans, inode);
458 if (ret) {
459 if (ret != -ENOSPC)
460 btrfs_abort_transaction(trans, root, ret);
461 goto out_put;
462 }
463 }
464
465 spin_lock(&root->cache_lock);
466 if (root->cached != BTRFS_CACHE_FINISHED) {
467 ret = -1;
468 spin_unlock(&root->cache_lock);
469 goto out_put;
470 }
471 spin_unlock(&root->cache_lock);
472
473 spin_lock(&ctl->tree_lock);
474 prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
475 prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
476 prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
477 spin_unlock(&ctl->tree_lock);
478
479 /* Just to make sure we have enough space */
480 prealloc += 8 * PAGE_CACHE_SIZE;
481
482 ret = btrfs_delalloc_reserve_space(inode, prealloc);
483 if (ret)
484 goto out_put;
485
486 ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
487 prealloc, prealloc, &alloc_hint);
488 if (ret) {
489 btrfs_delalloc_release_space(inode, prealloc);
490 goto out_put;
491 }
492 btrfs_free_reserved_data_space(inode, prealloc);
493
494 ret = btrfs_write_out_ino_cache(root, trans, path, inode);
495out_put:
496 iput(inode);
497out_release:
498 trace_btrfs_space_reservation(root->fs_info, "ino_cache",
499 trans->transid, trans->bytes_reserved, 0);
500 btrfs_block_rsv_release(root, trans->block_rsv, trans->bytes_reserved);
501out:
502 trans->block_rsv = rsv;
503 trans->bytes_reserved = num_bytes;
504
505 btrfs_free_path(path);
506 return ret;
507}
508
509static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
510{
511 struct btrfs_path *path;
512 int ret;
513 struct extent_buffer *l;
514 struct btrfs_key search_key;
515 struct btrfs_key found_key;
516 int slot;
517
518 path = btrfs_alloc_path();
519 if (!path)
520 return -ENOMEM;
521
522 search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
523 search_key.type = -1;
524 search_key.offset = (u64)-1;
525 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
526 if (ret < 0)
527 goto error;
528 BUG_ON(ret == 0); /* Corruption */
529 if (path->slots[0] > 0) {
530 slot = path->slots[0] - 1;
531 l = path->nodes[0];
532 btrfs_item_key_to_cpu(l, &found_key, slot);
533 *objectid = max_t(u64, found_key.objectid,
534 BTRFS_FIRST_FREE_OBJECTID - 1);
535 } else {
536 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
537 }
538 ret = 0;
539error:
540 btrfs_free_path(path);
541 return ret;
542}
543
544int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
545{
546 int ret;
547 mutex_lock(&root->objectid_mutex);
548
549 if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
550 ret = btrfs_find_highest_objectid(root,
551 &root->highest_objectid);
552 if (ret)
553 goto out;
554 }
555
556 if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
557 ret = -ENOSPC;
558 goto out;
559 }
560
561 *objectid = ++root->highest_objectid;
562 ret = 0;
563out:
564 mutex_unlock(&root->objectid_mutex);
565 return ret;
566}