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TOMOYO Linux Cross Reference
Linux/fs/btrfs/inode-map.c

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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 
 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 = 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(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(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_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->ino_cache_lock);
148         if (root->ino_cache_state != BTRFS_CACHE_NO) {
149                 spin_unlock(&root->ino_cache_lock);
150                 return;
151         }
152 
153         root->ino_cache_state = BTRFS_CACHE_STARTED;
154         spin_unlock(&root->ino_cache_lock);
155 
156         ret = load_free_ino_cache(root->fs_info, root);
157         if (ret == 1) {
158                 spin_lock(&root->ino_cache_lock);
159                 root->ino_cache_state = BTRFS_CACHE_FINISHED;
160                 spin_unlock(&root->ino_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",
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_pending_and_info(root->fs_info, INODE_MAP_CACHE,
182                                 "disabling inode map caching");
183         }
184 }
185 
186 int 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 
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->free_ino_ctl->free_space > 0);
202 
203         if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
204             root->free_ino_ctl->free_space == 0)
205                 return -ENOSPC;
206         else
207                 goto again;
208 }
209 
210 void 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;
216 again:
217         if (root->ino_cache_state == 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->ino_cache_lock);
222                 if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
223                         spin_unlock(&root->ino_cache_lock);
224                         up_write(&root->fs_info->commit_root_sem);
225                         goto again;
226                 }
227                 spin_unlock(&root->ino_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 are
239  * smaller than root->ino_cache_progress from pinned tree to free_ino tree, and
240  * others will just be dropped, because the commit root we were searching has
241  * changed.
242  *
243  * Must be called with root->fs_info->commit_root_sem held
244  */
245 void 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         spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
250         struct btrfs_free_space *info;
251         struct rb_node *n;
252         u64 count;
253 
254         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
255                 return;
256 
257         while (1) {
258                 bool add_to_ctl = true;
259 
260                 spin_lock(rbroot_lock);
261                 n = rb_first(rbroot);
262                 if (!n) {
263                         spin_unlock(rbroot_lock);
264                         break;
265                 }
266 
267                 info = rb_entry(n, struct btrfs_free_space, offset_index);
268                 BUG_ON(info->bitmap); /* Logic error */
269 
270                 if (info->offset > root->ino_cache_progress)
271                         add_to_ctl = false;
272                 else if (info->offset + info->bytes > root->ino_cache_progress)
273                         count = root->ino_cache_progress - info->offset + 1;
274                 else
275                         count = info->bytes;
276 
277                 rb_erase(&info->offset_index, rbroot);
278                 spin_unlock(rbroot_lock);
279                 if (add_to_ctl)
280                         __btrfs_add_free_space(ctl, info->offset, count);
281                 kmem_cache_free(btrfs_free_space_cachep, info);
282         }
283 }
284 
285 #define INIT_THRESHOLD  ((SZ_32K / 2) / sizeof(struct btrfs_free_space))
286 #define INODES_PER_BITMAP (PAGE_SIZE * 8)
287 
288 /*
289  * The goal is to keep the memory used by the free_ino tree won't
290  * exceed the memory if we use bitmaps only.
291  */
292 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
293 {
294         struct btrfs_free_space *info;
295         struct rb_node *n;
296         int max_ino;
297         int max_bitmaps;
298 
299         n = rb_last(&ctl->free_space_offset);
300         if (!n) {
301                 ctl->extents_thresh = INIT_THRESHOLD;
302                 return;
303         }
304         info = rb_entry(n, struct btrfs_free_space, offset_index);
305 
306         /*
307          * Find the maximum inode number in the filesystem. Note we
308          * ignore the fact that this can be a bitmap, because we are
309          * not doing precise calculation.
310          */
311         max_ino = info->bytes - 1;
312 
313         max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
314         if (max_bitmaps <= ctl->total_bitmaps) {
315                 ctl->extents_thresh = 0;
316                 return;
317         }
318 
319         ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
320                                 PAGE_SIZE / sizeof(*info);
321 }
322 
323 /*
324  * We don't fall back to bitmap, if we are below the extents threshold
325  * or this chunk of inode numbers is a big one.
326  */
327 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
328                        struct btrfs_free_space *info)
329 {
330         if (ctl->free_extents < ctl->extents_thresh ||
331             info->bytes > INODES_PER_BITMAP / 10)
332                 return false;
333 
334         return true;
335 }
336 
337 static const struct btrfs_free_space_op free_ino_op = {
338         .recalc_thresholds      = recalculate_thresholds,
339         .use_bitmap             = use_bitmap,
340 };
341 
342 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
343 {
344 }
345 
346 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
347                               struct btrfs_free_space *info)
348 {
349         /*
350          * We always use extents for two reasons:
351          *
352          * - The pinned tree is only used during the process of caching
353          *   work.
354          * - Make code simpler. See btrfs_unpin_free_ino().
355          */
356         return false;
357 }
358 
359 static const struct btrfs_free_space_op pinned_free_ino_op = {
360         .recalc_thresholds      = pinned_recalc_thresholds,
361         .use_bitmap             = pinned_use_bitmap,
362 };
363 
364 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
365 {
366         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
367         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
368 
369         spin_lock_init(&ctl->tree_lock);
370         ctl->unit = 1;
371         ctl->start = 0;
372         ctl->private = NULL;
373         ctl->op = &free_ino_op;
374         INIT_LIST_HEAD(&ctl->trimming_ranges);
375         mutex_init(&ctl->cache_writeout_mutex);
376 
377         /*
378          * Initially we allow to use 16K of ram to cache chunks of
379          * inode numbers before we resort to bitmaps. This is somewhat
380          * arbitrary, but it will be adjusted in runtime.
381          */
382         ctl->extents_thresh = INIT_THRESHOLD;
383 
384         spin_lock_init(&pinned->tree_lock);
385         pinned->unit = 1;
386         pinned->start = 0;
387         pinned->private = NULL;
388         pinned->extents_thresh = 0;
389         pinned->op = &pinned_free_ino_op;
390 }
391 
392 int btrfs_save_ino_cache(struct btrfs_root *root,
393                          struct btrfs_trans_handle *trans)
394 {
395         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
396         struct btrfs_path *path;
397         struct inode *inode;
398         struct btrfs_block_rsv *rsv;
399         u64 num_bytes;
400         u64 alloc_hint = 0;
401         int ret;
402         int prealloc;
403         bool retry = false;
404 
405         /* only fs tree and subvol/snap needs ino cache */
406         if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
407             (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
408              root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
409                 return 0;
410 
411         /* Don't save inode cache if we are deleting this root */
412         if (btrfs_root_refs(&root->root_item) == 0)
413                 return 0;
414 
415         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
416                 return 0;
417 
418         path = btrfs_alloc_path();
419         if (!path)
420                 return -ENOMEM;
421 
422         rsv = trans->block_rsv;
423         trans->block_rsv = &root->fs_info->trans_block_rsv;
424 
425         num_bytes = trans->bytes_reserved;
426         /*
427          * 1 item for inode item insertion if need
428          * 4 items for inode item update (in the worst case)
429          * 1 items for slack space if we need do truncation
430          * 1 item for free space object
431          * 3 items for pre-allocation
432          */
433         trans->bytes_reserved = btrfs_calc_trans_metadata_size(root, 10);
434         ret = btrfs_block_rsv_add(root, trans->block_rsv,
435                                   trans->bytes_reserved,
436                                   BTRFS_RESERVE_NO_FLUSH);
437         if (ret)
438                 goto out;
439         trace_btrfs_space_reservation(root->fs_info, "ino_cache",
440                                       trans->transid, trans->bytes_reserved, 1);
441 again:
442         inode = lookup_free_ino_inode(root, path);
443         if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
444                 ret = PTR_ERR(inode);
445                 goto out_release;
446         }
447 
448         if (IS_ERR(inode)) {
449                 BUG_ON(retry); /* Logic error */
450                 retry = true;
451 
452                 ret = create_free_ino_inode(root, trans, path);
453                 if (ret)
454                         goto out_release;
455                 goto again;
456         }
457 
458         BTRFS_I(inode)->generation = 0;
459         ret = btrfs_update_inode(trans, root, inode);
460         if (ret) {
461                 btrfs_abort_transaction(trans, root, ret);
462                 goto out_put;
463         }
464 
465         if (i_size_read(inode) > 0) {
466                 ret = btrfs_truncate_free_space_cache(root, trans, NULL, inode);
467                 if (ret) {
468                         if (ret != -ENOSPC)
469                                 btrfs_abort_transaction(trans, root, ret);
470                         goto out_put;
471                 }
472         }
473 
474         spin_lock(&root->ino_cache_lock);
475         if (root->ino_cache_state != BTRFS_CACHE_FINISHED) {
476                 ret = -1;
477                 spin_unlock(&root->ino_cache_lock);
478                 goto out_put;
479         }
480         spin_unlock(&root->ino_cache_lock);
481 
482         spin_lock(&ctl->tree_lock);
483         prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
484         prealloc = ALIGN(prealloc, PAGE_SIZE);
485         prealloc += ctl->total_bitmaps * PAGE_SIZE;
486         spin_unlock(&ctl->tree_lock);
487 
488         /* Just to make sure we have enough space */
489         prealloc += 8 * PAGE_SIZE;
490 
491         ret = btrfs_delalloc_reserve_space(inode, 0, prealloc);
492         if (ret)
493                 goto out_put;
494 
495         ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
496                                               prealloc, prealloc, &alloc_hint);
497         if (ret) {
498                 btrfs_delalloc_release_space(inode, 0, prealloc);
499                 goto out_put;
500         }
501         btrfs_free_reserved_data_space(inode, 0, prealloc);
502 
503         ret = btrfs_write_out_ino_cache(root, trans, path, inode);
504 out_put:
505         iput(inode);
506 out_release:
507         trace_btrfs_space_reservation(root->fs_info, "ino_cache",
508                                       trans->transid, trans->bytes_reserved, 0);
509         btrfs_block_rsv_release(root, trans->block_rsv, trans->bytes_reserved);
510 out:
511         trans->block_rsv = rsv;
512         trans->bytes_reserved = num_bytes;
513 
514         btrfs_free_path(path);
515         return ret;
516 }
517 
518 int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
519 {
520         struct btrfs_path *path;
521         int ret;
522         struct extent_buffer *l;
523         struct btrfs_key search_key;
524         struct btrfs_key found_key;
525         int slot;
526 
527         path = btrfs_alloc_path();
528         if (!path)
529                 return -ENOMEM;
530 
531         search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
532         search_key.type = -1;
533         search_key.offset = (u64)-1;
534         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
535         if (ret < 0)
536                 goto error;
537         BUG_ON(ret == 0); /* Corruption */
538         if (path->slots[0] > 0) {
539                 slot = path->slots[0] - 1;
540                 l = path->nodes[0];
541                 btrfs_item_key_to_cpu(l, &found_key, slot);
542                 *objectid = max_t(u64, found_key.objectid,
543                                   BTRFS_FIRST_FREE_OBJECTID - 1);
544         } else {
545                 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
546         }
547         ret = 0;
548 error:
549         btrfs_free_path(path);
550         return ret;
551 }
552 
553 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
554 {
555         int ret;
556         mutex_lock(&root->objectid_mutex);
557 
558         if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
559                 btrfs_warn(root->fs_info,
560                            "the objectid of root %llu reaches its highest value",
561                            root->root_key.objectid);
562                 ret = -ENOSPC;
563                 goto out;
564         }
565 
566         *objectid = ++root->highest_objectid;
567         ret = 0;
568 out:
569         mutex_unlock(&root->objectid_mutex);
570         return ret;
571 }
572 

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