GNU Linux-libre 4.9.308-gnu1
[releases.git] / fs / btrfs / inode-map.c
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
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->fs_info, 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 = READA_FORWARD;
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         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->ino_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(fs_info, ctl, last + 1,
108                                                key.objectid - last - 1);
109                         wake_up(&root->ino_cache_wait);
110                 }
111
112                 last = key.objectid;
113 next:
114                 path->slots[0]++;
115         }
116
117         if (last < root->highest_objectid - 1) {
118                 __btrfs_add_free_space(fs_info, ctl, last + 1,
119                                        root->highest_objectid - last - 1);
120         }
121
122         spin_lock(&root->ino_cache_lock);
123         root->ino_cache_state = BTRFS_CACHE_FINISHED;
124         spin_unlock(&root->ino_cache_lock);
125
126         root->ino_cache_progress = (u64)-1;
127         btrfs_unpin_free_ino(root);
128 out:
129         wake_up(&root->ino_cache_wait);
130         up_read(&fs_info->commit_root_sem);
131
132         btrfs_free_path(path);
133
134         return ret;
135 }
136
137 static void start_caching(struct btrfs_root *root)
138 {
139         struct btrfs_fs_info *fs_info = root->fs_info;
140         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
141         struct task_struct *tsk;
142         int ret;
143         u64 objectid;
144
145         if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
146                 return;
147
148         spin_lock(&root->ino_cache_lock);
149         if (root->ino_cache_state != BTRFS_CACHE_NO) {
150                 spin_unlock(&root->ino_cache_lock);
151                 return;
152         }
153
154         root->ino_cache_state = BTRFS_CACHE_STARTED;
155         spin_unlock(&root->ino_cache_lock);
156
157         ret = load_free_ino_cache(fs_info, root);
158         if (ret == 1) {
159                 spin_lock(&root->ino_cache_lock);
160                 root->ino_cache_state = BTRFS_CACHE_FINISHED;
161                 spin_unlock(&root->ino_cache_lock);
162                 wake_up(&root->ino_cache_wait);
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(fs_info, ctl, objectid,
176                                        BTRFS_LAST_FREE_OBJECTID - objectid + 1);
177         }
178
179         tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
180                           root->root_key.objectid);
181         if (IS_ERR(tsk)) {
182                 btrfs_warn(fs_info, "failed to start inode caching task");
183                 btrfs_clear_pending_and_info(fs_info, INODE_MAP_CACHE,
184                                 "disabling inode map caching");
185         }
186 }
187
188 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
189 {
190         if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
191                 return btrfs_find_free_objectid(root, objectid);
192
193 again:
194         *objectid = btrfs_find_ino_for_alloc(root);
195
196         if (*objectid != 0)
197                 return 0;
198
199         start_caching(root);
200
201         wait_event(root->ino_cache_wait,
202                    root->ino_cache_state == BTRFS_CACHE_FINISHED ||
203                    root->free_ino_ctl->free_space > 0);
204
205         if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
206             root->free_ino_ctl->free_space == 0)
207                 return -ENOSPC;
208         else
209                 goto again;
210 }
211
212 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
213 {
214         struct btrfs_fs_info *fs_info = root->fs_info;
215         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
216
217         if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
218                 return;
219 again:
220         if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
221                 __btrfs_add_free_space(fs_info, pinned, objectid, 1);
222         } else {
223                 down_write(&fs_info->commit_root_sem);
224                 spin_lock(&root->ino_cache_lock);
225                 if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
226                         spin_unlock(&root->ino_cache_lock);
227                         up_write(&fs_info->commit_root_sem);
228                         goto again;
229                 }
230                 spin_unlock(&root->ino_cache_lock);
231
232                 start_caching(root);
233
234                 __btrfs_add_free_space(fs_info, pinned, objectid, 1);
235
236                 up_write(&fs_info->commit_root_sem);
237         }
238 }
239
240 /*
241  * When a transaction is committed, we'll move those inode numbers which are
242  * smaller than root->ino_cache_progress from pinned tree to free_ino tree, and
243  * others will just be dropped, because the commit root we were searching has
244  * changed.
245  *
246  * Must be called with root->fs_info->commit_root_sem held
247  */
248 void btrfs_unpin_free_ino(struct btrfs_root *root)
249 {
250         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
251         struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
252         spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
253         struct btrfs_free_space *info;
254         struct rb_node *n;
255         u64 count;
256
257         if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
258                 return;
259
260         while (1) {
261                 bool add_to_ctl = true;
262
263                 spin_lock(rbroot_lock);
264                 n = rb_first(rbroot);
265                 if (!n) {
266                         spin_unlock(rbroot_lock);
267                         break;
268                 }
269
270                 info = rb_entry(n, struct btrfs_free_space, offset_index);
271                 BUG_ON(info->bitmap); /* Logic error */
272
273                 if (info->offset > root->ino_cache_progress)
274                         add_to_ctl = false;
275                 else if (info->offset + info->bytes > root->ino_cache_progress)
276                         count = root->ino_cache_progress - info->offset + 1;
277                 else
278                         count = info->bytes;
279
280                 rb_erase(&info->offset_index, rbroot);
281                 spin_unlock(rbroot_lock);
282                 if (add_to_ctl)
283                         __btrfs_add_free_space(root->fs_info, ctl,
284                                                info->offset, count);
285                 kmem_cache_free(btrfs_free_space_cachep, info);
286         }
287 }
288
289 #define INIT_THRESHOLD  ((SZ_32K / 2) / sizeof(struct btrfs_free_space))
290 #define INODES_PER_BITMAP (PAGE_SIZE * 8)
291
292 /*
293  * The goal is to keep the memory used by the free_ino tree won't
294  * exceed the memory if we use bitmaps only.
295  */
296 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
297 {
298         struct btrfs_free_space *info;
299         struct rb_node *n;
300         int max_ino;
301         int max_bitmaps;
302
303         n = rb_last(&ctl->free_space_offset);
304         if (!n) {
305                 ctl->extents_thresh = INIT_THRESHOLD;
306                 return;
307         }
308         info = rb_entry(n, struct btrfs_free_space, offset_index);
309
310         /*
311          * Find the maximum inode number in the filesystem. Note we
312          * ignore the fact that this can be a bitmap, because we are
313          * not doing precise calculation.
314          */
315         max_ino = info->bytes - 1;
316
317         max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
318         if (max_bitmaps <= ctl->total_bitmaps) {
319                 ctl->extents_thresh = 0;
320                 return;
321         }
322
323         ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
324                                 PAGE_SIZE / sizeof(*info);
325 }
326
327 /*
328  * We don't fall back to bitmap, if we are below the extents threshold
329  * or this chunk of inode numbers is a big one.
330  */
331 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
332                        struct btrfs_free_space *info)
333 {
334         if (ctl->free_extents < ctl->extents_thresh ||
335             info->bytes > INODES_PER_BITMAP / 10)
336                 return false;
337
338         return true;
339 }
340
341 static const struct btrfs_free_space_op free_ino_op = {
342         .recalc_thresholds      = recalculate_thresholds,
343         .use_bitmap             = use_bitmap,
344 };
345
346 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
347 {
348 }
349
350 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
351                               struct btrfs_free_space *info)
352 {
353         /*
354          * We always use extents for two reasons:
355          *
356          * - The pinned tree is only used during the process of caching
357          *   work.
358          * - Make code simpler. See btrfs_unpin_free_ino().
359          */
360         return false;
361 }
362
363 static const struct btrfs_free_space_op pinned_free_ino_op = {
364         .recalc_thresholds      = pinned_recalc_thresholds,
365         .use_bitmap             = pinned_use_bitmap,
366 };
367
368 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
369 {
370         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
371         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
372
373         spin_lock_init(&ctl->tree_lock);
374         ctl->unit = 1;
375         ctl->start = 0;
376         ctl->private = NULL;
377         ctl->op = &free_ino_op;
378         INIT_LIST_HEAD(&ctl->trimming_ranges);
379         mutex_init(&ctl->cache_writeout_mutex);
380
381         /*
382          * Initially we allow to use 16K of ram to cache chunks of
383          * inode numbers before we resort to bitmaps. This is somewhat
384          * arbitrary, but it will be adjusted in runtime.
385          */
386         ctl->extents_thresh = INIT_THRESHOLD;
387
388         spin_lock_init(&pinned->tree_lock);
389         pinned->unit = 1;
390         pinned->start = 0;
391         pinned->private = NULL;
392         pinned->extents_thresh = 0;
393         pinned->op = &pinned_free_ino_op;
394 }
395
396 int btrfs_save_ino_cache(struct btrfs_root *root,
397                          struct btrfs_trans_handle *trans)
398 {
399         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
400         struct btrfs_path *path;
401         struct inode *inode;
402         struct btrfs_block_rsv *rsv;
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(root->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 = &root->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(root, 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(root->fs_info, "ino_cache",
444                                       trans->transid, 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(root, 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, 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_metadata(inode, prealloc);
503                 goto out_put;
504         }
505
506         ret = btrfs_write_out_ino_cache(root, trans, path, inode);
507 out_put:
508         iput(inode);
509 out_release:
510         trace_btrfs_space_reservation(root->fs_info, "ino_cache",
511                                       trans->transid, trans->bytes_reserved, 0);
512         btrfs_block_rsv_release(root, trans->block_rsv, trans->bytes_reserved);
513 out:
514         trans->block_rsv = rsv;
515         trans->bytes_reserved = num_bytes;
516
517         btrfs_free_path(path);
518         return ret;
519 }
520
521 int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
522 {
523         struct btrfs_path *path;
524         int ret;
525         struct extent_buffer *l;
526         struct btrfs_key search_key;
527         struct btrfs_key found_key;
528         int slot;
529
530         path = btrfs_alloc_path();
531         if (!path)
532                 return -ENOMEM;
533
534         search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
535         search_key.type = -1;
536         search_key.offset = (u64)-1;
537         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
538         if (ret < 0)
539                 goto error;
540         BUG_ON(ret == 0); /* Corruption */
541         if (path->slots[0] > 0) {
542                 slot = path->slots[0] - 1;
543                 l = path->nodes[0];
544                 btrfs_item_key_to_cpu(l, &found_key, slot);
545                 *objectid = max_t(u64, found_key.objectid,
546                                   BTRFS_FIRST_FREE_OBJECTID - 1);
547         } else {
548                 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
549         }
550         ret = 0;
551 error:
552         btrfs_free_path(path);
553         return ret;
554 }
555
556 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
557 {
558         int ret;
559         mutex_lock(&root->objectid_mutex);
560
561         if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
562                 btrfs_warn(root->fs_info,
563                            "the objectid of root %llu reaches its highest value",
564                            root->root_key.objectid);
565                 ret = -ENOSPC;
566                 goto out;
567         }
568
569         *objectid = ++root->highest_objectid;
570         ret = 0;
571 out:
572         mutex_unlock(&root->objectid_mutex);
573         return ret;
574 }