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, 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         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                 wake_up(&root->ino_cache_wait);
 162                 return;
 163         }
 164
 165         /*
 166          * It can be quite time-consuming to fill the cache by searching
 167          * through the extent tree, and this can keep ino allocation path
 168          * waiting. Therefore at start we quickly find out the highest
 169          * inode number and we know we can use inode numbers which fall in
 170          * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
 171          */
 172         ret = btrfs_find_free_objectid(root, &objectid);
 173         if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
 174                 __btrfs_add_free_space(ctl, objectid,
 175                                        BTRFS_LAST_FREE_OBJECTID - objectid + 1);
 176         }
 177
 178         tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
 179                           root->root_key.objectid);
 180         if (IS_ERR(tsk)) {
 181                 btrfs_warn(root->fs_info, "failed to start inode caching task");
 182                 btrfs_clear_pending_and_info(root->fs_info, INODE_MAP_CACHE,
 183                                 "disabling inode map caching");
 184         }
 185 }
 186
 187 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
 188 {
 189         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 190                 return btrfs_find_free_objectid(root, objectid);
 191
 192 again:
 193         *objectid = btrfs_find_ino_for_alloc(root);
 194
 195         if (*objectid != 0)
 196                 return 0;
 197
 198         start_caching(root);
 199
 200         wait_event(root->ino_cache_wait,
 201                    root->ino_cache_state == BTRFS_CACHE_FINISHED ||
 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
 208                 goto again;
 209 }
 210
 211 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
 212 {
 213         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 214
 215         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 216                 return;
 217 again:
 218         if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
 219                 __btrfs_add_free_space(pinned, objectid, 1);
 220         } else {
 221                 down_write(&root->fs_info->commit_root_sem);
 222                 spin_lock(&root->ino_cache_lock);
 223                 if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
 224                         spin_unlock(&root->ino_cache_lock);
 225                         up_write(&root->fs_info->commit_root_sem);
 226                         goto again;
 227                 }
 228                 spin_unlock(&root->ino_cache_lock);
 229
 230                 start_caching(root);
 231
 232                 __btrfs_add_free_space(pinned, objectid, 1);
 233
 234                 up_write(&root->fs_info->commit_root_sem);
 235         }
 236 }
 237
 238 /*
 239  * When a transaction is committed, we'll move those inode numbers which are
 240  * smaller than root->ino_cache_progress from pinned tree to free_ino tree, and
 241  * others will just be dropped, because the commit root we were searching has
 242  * changed.
 243  *
 244  * Must be called with root->fs_info->commit_root_sem held
 245  */
 246 void btrfs_unpin_free_ino(struct btrfs_root *root)
 247 {
 248         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 249         struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
 250         spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
 251         struct btrfs_free_space *info;
 252         struct rb_node *n;
 253         u64 count;
 254
 255         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 256                 return;
 257
 258         while (1) {
 259                 bool add_to_ctl = true;
 260
 261                 spin_lock(rbroot_lock);
 262                 n = rb_first(rbroot);
 263                 if (!n) {
 264                         spin_unlock(rbroot_lock);
 265                         break;
 266                 }
 267
 268                 info = rb_entry(n, struct btrfs_free_space, offset_index);
 269                 BUG_ON(info->bitmap); /* Logic error */
 270
 271                 if (info->offset > root->ino_cache_progress)
 272                         add_to_ctl = false;
 273                 else if (info->offset + info->bytes > root->ino_cache_progress)
 274                         count = root->ino_cache_progress - info->offset + 1;
 275                 else
 276                         count = info->bytes;
 277
 278                 rb_erase(&info->offset_index, rbroot);
 279                 spin_unlock(rbroot_lock);
 280                 if (add_to_ctl)
 281                         __btrfs_add_free_space(ctl, info->offset, count);
 282                 kmem_cache_free(btrfs_free_space_cachep, info);
 283         }
 284 }
 285
 286 #define INIT_THRESHOLD  (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
 287 #define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
 288
 289 /*
 290  * The goal is to keep the memory used by the free_ino tree won't
 291  * exceed the memory if we use bitmaps only.
 292  */
 293 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
 294 {
 295         struct btrfs_free_space *info;
 296         struct rb_node *n;
 297         int max_ino;
 298         int max_bitmaps;
 299
 300         n = rb_last(&ctl->free_space_offset);
 301         if (!n) {
 302                 ctl->extents_thresh = INIT_THRESHOLD;
 303                 return;
 304         }
 305         info = rb_entry(n, struct btrfs_free_space, offset_index);
 306
 307         /*
 308          * Find the maximum inode number in the filesystem. Note we
 309          * ignore the fact that this can be a bitmap, because we are
 310          * not doing precise calculation.
 311          */
 312         max_ino = info->bytes - 1;
 313
 314         max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
 315         if (max_bitmaps <= ctl->total_bitmaps) {
 316                 ctl->extents_thresh = 0;
 317                 return;
 318         }
 319
 320         ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
 321                                 PAGE_CACHE_SIZE / sizeof(*info);
 322 }
 323
 324 /*
 325  * We don't fall back to bitmap, if we are below the extents threshold
 326  * or this chunk of inode numbers is a big one.
 327  */
 328 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
 329                        struct btrfs_free_space *info)
 330 {
 331         if (ctl->free_extents < ctl->extents_thresh ||
 332             info->bytes > INODES_PER_BITMAP / 10)
 333                 return false;
 334
 335         return true;
 336 }
 337
 338 static struct btrfs_free_space_op free_ino_op = {
 339         .recalc_thresholds      = recalculate_thresholds,
 340         .use_bitmap             = use_bitmap,
 341 };
 342
 343 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
 344 {
 345 }
 346
 347 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
 348                               struct btrfs_free_space *info)
 349 {
 350         /*
 351          * We always use extents for two reasons:
 352          *
 353          * - The pinned tree is only used during the process of caching
 354          *   work.
 355          * - Make code simpler. See btrfs_unpin_free_ino().
 356          */
 357         return false;
 358 }
 359
 360 static struct btrfs_free_space_op pinned_free_ino_op = {
 361         .recalc_thresholds      = pinned_recalc_thresholds,
 362         .use_bitmap             = pinned_use_bitmap,
 363 };
 364
 365 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
 366 {
 367         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 368         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 369
 370         spin_lock_init(&ctl->tree_lock);
 371         ctl->unit = 1;
 372         ctl->start = 0;
 373         ctl->private = NULL;
 374         ctl->op = &free_ino_op;
 375         INIT_LIST_HEAD(&ctl->trimming_ranges);
 376         mutex_init(&ctl->cache_writeout_mutex);
 377
 378         /*
 379          * Initially we allow to use 16K of ram to cache chunks of
 380          * inode numbers before we resort to bitmaps. This is somewhat
 381          * arbitrary, but it will be adjusted in runtime.
 382          */
 383         ctl->extents_thresh = INIT_THRESHOLD;
 384
 385         spin_lock_init(&pinned->tree_lock);
 386         pinned->unit = 1;
 387         pinned->start = 0;
 388         pinned->private = NULL;
 389         pinned->extents_thresh = 0;
 390         pinned->op = &pinned_free_ino_op;
 391 }
 392
 393 int btrfs_save_ino_cache(struct btrfs_root *root,
 394                          struct btrfs_trans_handle *trans)
 395 {
 396         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 397         struct btrfs_path *path;
 398         struct inode *inode;
 399         struct btrfs_block_rsv *rsv;
 400         u64 num_bytes;
 401         u64 alloc_hint = 0;
 402         int ret;
 403         int prealloc;
 404         bool retry = false;
 405
 406         /* only fs tree and subvol/snap needs ino cache */
 407         if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
 408             (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
 409              root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
 410                 return 0;
 411
 412         /* Don't save inode cache if we are deleting this root */
 413         if (btrfs_root_refs(&root->root_item) == 0)
 414                 return 0;
 415
 416         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 417                 return 0;
 418
 419         path = btrfs_alloc_path();
 420         if (!path)
 421                 return -ENOMEM;
 422
 423         rsv = trans->block_rsv;
 424         trans->block_rsv = &root->fs_info->trans_block_rsv;
 425
 426         num_bytes = trans->bytes_reserved;
 427         /*
 428          * 1 item for inode item insertion if need
 429          * 4 items for inode item update (in the worst case)
 430          * 1 items for slack space if we need do truncation
 431          * 1 item for free space object
 432          * 3 items for pre-allocation
 433          */
 434         trans->bytes_reserved = btrfs_calc_trans_metadata_size(root, 10);
 435         ret = btrfs_block_rsv_add(root, trans->block_rsv,
 436                                   trans->bytes_reserved,
 437                                   BTRFS_RESERVE_NO_FLUSH);
 438         if (ret)
 439                 goto out;
 440         trace_btrfs_space_reservation(root->fs_info, "ino_cache",
 441                                       trans->transid, trans->bytes_reserved, 1);
 442 again:
 443         inode = lookup_free_ino_inode(root, path);
 444         if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
 445                 ret = PTR_ERR(inode);
 446                 goto out_release;
 447         }
 448
 449         if (IS_ERR(inode)) {
 450                 BUG_ON(retry); /* Logic error */
 451                 retry = true;
 452
 453                 ret = create_free_ino_inode(root, trans, path);
 454                 if (ret)
 455                         goto out_release;
 456                 goto again;
 457         }
 458
 459         BTRFS_I(inode)->generation = 0;
 460         ret = btrfs_update_inode(trans, root, inode);
 461         if (ret) {
 462                 btrfs_abort_transaction(trans, root, ret);
 463                 goto out_put;
 464         }
 465
 466         if (i_size_read(inode) > 0) {
 467                 ret = btrfs_truncate_free_space_cache(root, trans, NULL, inode);
 468                 if (ret) {
 469                         if (ret != -ENOSPC)
 470                                 btrfs_abort_transaction(trans, root, ret);
 471                         goto out_put;
 472                 }
 473         }
 474
 475         spin_lock(&root->ino_cache_lock);
 476         if (root->ino_cache_state != BTRFS_CACHE_FINISHED) {
 477                 ret = -1;
 478                 spin_unlock(&root->ino_cache_lock);
 479                 goto out_put;
 480         }
 481         spin_unlock(&root->ino_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, 0, 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, 0, prealloc);
 500                 goto out_put;
 501         }
 502         btrfs_free_reserved_data_space(inode, 0, prealloc);
 503
 504         ret = btrfs_write_out_ino_cache(root, trans, path, inode);
 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
 519 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
 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_LAST_FREE_OBJECTID)) {
 560                 ret = -ENOSPC;
 561                 goto out;
 562         }
 563
 564         *objectid = ++root->highest_objectid;
 565         ret = 0;
 566 out:
 567         mutex_unlock(&root->objectid_mutex);
 568         return ret;
 569 }