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         path = btrfs_alloc_path();
  42         if (!path)
  43                 return -ENOMEM;
  44
  45         /* Since the commit root is read-only, we can safely skip locking. */
  46         path->skip_locking = 1;
  47         path->search_commit_root = 1;
  48         path->reada = 2;
  49
  50         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
  51         key.offset = 0;
  52         key.type = BTRFS_INODE_ITEM_KEY;
  53 again:
  54         /* need to make sure the commit_root doesn't disappear */
  55         mutex_lock(&root->fs_commit_mutex);
  56
  57         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  58         if (ret < 0)
  59                 goto out;
  60
  61         while (1) {
  62                 smp_mb();
  63                 if (fs_info->closing > 1)
  64                         goto out;
  65
  66                 leaf = path->nodes[0];
  67                 slot = path->slots[0];
  68                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
  69                         ret = btrfs_next_leaf(root, path);
  70                         if (ret < 0)
  71                                 goto out;
  72                         else if (ret > 0)
  73                                 break;
  74
  75                         if (need_resched() ||
  76                             btrfs_transaction_in_commit(fs_info)) {
  77                                 leaf = path->nodes[0];
  78
  79                                 if (btrfs_header_nritems(leaf) == 0) {
  80                                         WARN_ON(1);
  81                                         break;
  82                                 }
  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                                 mutex_unlock(&root->fs_commit_mutex);
  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 >= BTRFS_LAST_FREE_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;
 113 next:
 114                 path->slots[0]++;
 115         }
 116
 117         if (last < BTRFS_LAST_FREE_OBJECTID - 1) {
 118                 __btrfs_add_free_space(ctl, last + 1,
 119                                        BTRFS_LAST_FREE_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);
 128 out:
 129         wake_up(&root->cache_wait);
 130         mutex_unlock(&root->fs_commit_mutex);
 131
 132         btrfs_free_path(path);
 133
 134         return ret;
 135 }
 136
 137 static void start_caching(struct btrfs_root *root)
 138 {
 139         struct task_struct *tsk;
 140         int ret;
 141
 142         spin_lock(&root->cache_lock);
 143         if (root->cached != BTRFS_CACHE_NO) {
 144                 spin_unlock(&root->cache_lock);
 145                 return;
 146         }
 147
 148         root->cached = BTRFS_CACHE_STARTED;
 149         spin_unlock(&root->cache_lock);
 150
 151         ret = load_free_ino_cache(root->fs_info, root);
 152         if (ret == 1) {
 153                 spin_lock(&root->cache_lock);
 154                 root->cached = BTRFS_CACHE_FINISHED;
 155                 spin_unlock(&root->cache_lock);
 156                 return;
 157         }
 158
 159         tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
 160                           root->root_key.objectid);
 161         BUG_ON(IS_ERR(tsk));
 162 }
 163
 164 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
 165 {
 166 again:
 167         *objectid = btrfs_find_ino_for_alloc(root);
 168
 169         if (*objectid != 0)
 170                 return 0;
 171
 172         start_caching(root);
 173
 174         wait_event(root->cache_wait,
 175                    root->cached == BTRFS_CACHE_FINISHED ||
 176                    root->free_ino_ctl->free_space > 0);
 177
 178         if (root->cached == BTRFS_CACHE_FINISHED &&
 179             root->free_ino_ctl->free_space == 0)
 180                 return -ENOSPC;
 181         else
 182                 goto again;
 183 }
 184
 185 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
 186 {
 187         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 188         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 189 again:
 190         if (root->cached == BTRFS_CACHE_FINISHED) {
 191                 __btrfs_add_free_space(ctl, objectid, 1);
 192         } else {
 193                 /*
 194                  * If we are in the process of caching free ino chunks,
 195                  * to avoid adding the same inode number to the free_ino
 196                  * tree twice due to cross transaction, we'll leave it
 197                  * in the pinned tree until a transaction is committed
 198                  * or the caching work is done.
 199                  */
 200
 201                 mutex_lock(&root->fs_commit_mutex);
 202                 spin_lock(&root->cache_lock);
 203                 if (root->cached == BTRFS_CACHE_FINISHED) {
 204                         spin_unlock(&root->cache_lock);
 205                         mutex_unlock(&root->fs_commit_mutex);
 206                         goto again;
 207                 }
 208                 spin_unlock(&root->cache_lock);
 209
 210                 start_caching(root);
 211
 212                 if (objectid <= root->cache_progress)
 213                         __btrfs_add_free_space(ctl, objectid, 1);
 214                 else
 215                         __btrfs_add_free_space(pinned, objectid, 1);
 216
 217                 mutex_unlock(&root->fs_commit_mutex);
 218         }
 219 }
 220
 221 /*
 222  * When a transaction is committed, we'll move those inode numbers which
 223  * are smaller than root->cache_progress from pinned tree to free_ino tree,
 224  * and others will just be dropped, because the commit root we were
 225  * searching has changed.
 226  *
 227  * Must be called with root->fs_commit_mutex held
 228  */
 229 void btrfs_unpin_free_ino(struct btrfs_root *root)
 230 {
 231         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 232         struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
 233         struct btrfs_free_space *info;
 234         struct rb_node *n;
 235         u64 count;
 236
 237         while (1) {
 238                 n = rb_first(rbroot);
 239                 if (!n)
 240                         break;
 241
 242                 info = rb_entry(n, struct btrfs_free_space, offset_index);
 243                 BUG_ON(info->bitmap);
 244
 245                 if (info->offset > root->cache_progress)
 246                         goto free;
 247                 else if (info->offset + info->bytes > root->cache_progress)
 248                         count = root->cache_progress - info->offset + 1;
 249                 else
 250                         count = info->bytes;
 251
 252                 __btrfs_add_free_space(ctl, info->offset, count);
 253 free:
 254                 rb_erase(&info->offset_index, rbroot);
 255                 kfree(info);
 256         }
 257 }
 258
 259 #define INIT_THRESHOLD  (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
 260 #define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
 261
 262 /*
 263  * The goal is to keep the memory used by the free_ino tree won't
 264  * exceed the memory if we use bitmaps only.
 265  */
 266 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
 267 {
 268         struct btrfs_free_space *info;
 269         struct rb_node *n;
 270         int max_ino;
 271         int max_bitmaps;
 272
 273         n = rb_last(&ctl->free_space_offset);
 274         if (!n) {
 275                 ctl->extents_thresh = INIT_THRESHOLD;
 276                 return;
 277         }
 278         info = rb_entry(n, struct btrfs_free_space, offset_index);
 279
 280         /*
 281          * Find the maximum inode number in the filesystem. Note we
 282          * ignore the fact that this can be a bitmap, because we are
 283          * not doing precise calculation.
 284          */
 285         max_ino = info->bytes - 1;
 286
 287         max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
 288         if (max_bitmaps <= ctl->total_bitmaps) {
 289                 ctl->extents_thresh = 0;
 290                 return;
 291         }
 292
 293         ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
 294                                 PAGE_CACHE_SIZE / sizeof(*info);
 295 }
 296
 297 /*
 298  * We don't fall back to bitmap, if we are below the extents threshold
 299  * or this chunk of inode numbers is a big one.
 300  */
 301 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
 302                        struct btrfs_free_space *info)
 303 {
 304         if (ctl->free_extents < ctl->extents_thresh ||
 305             info->bytes > INODES_PER_BITMAP / 10)
 306                 return false;
 307
 308         return true;
 309 }
 310
 311 static struct btrfs_free_space_op free_ino_op = {
 312         .recalc_thresholds      = recalculate_thresholds,
 313         .use_bitmap             = use_bitmap,
 314 };
 315
 316 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
 317 {
 318 }
 319
 320 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
 321                               struct btrfs_free_space *info)
 322 {
 323         /*
 324          * We always use extents for two reasons:
 325          *
 326          * - The pinned tree is only used during the process of caching
 327          *   work.
 328          * - Make code simpler. See btrfs_unpin_free_ino().
 329          */
 330         return false;
 331 }
 332
 333 static struct btrfs_free_space_op pinned_free_ino_op = {
 334         .recalc_thresholds      = pinned_recalc_thresholds,
 335         .use_bitmap             = pinned_use_bitmap,
 336 };
 337
 338 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
 339 {
 340         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 341         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 342
 343         spin_lock_init(&ctl->tree_lock);
 344         ctl->unit = 1;
 345         ctl->start = 0;
 346         ctl->private = NULL;
 347         ctl->op = &free_ino_op;
 348
 349         /*
 350          * Initially we allow to use 16K of ram to cache chunks of
 351          * inode numbers before we resort to bitmaps. This is somewhat
 352          * arbitrary, but it will be adjusted in runtime.
 353          */
 354         ctl->extents_thresh = INIT_THRESHOLD;
 355
 356         spin_lock_init(&pinned->tree_lock);
 357         pinned->unit = 1;
 358         pinned->start = 0;
 359         pinned->private = NULL;
 360         pinned->extents_thresh = 0;
 361         pinned->op = &pinned_free_ino_op;
 362 }
 363
 364 int btrfs_save_ino_cache(struct btrfs_root *root,
 365                          struct btrfs_trans_handle *trans)
 366 {
 367         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 368         struct btrfs_path *path;
 369         struct inode *inode;
 370         u64 alloc_hint = 0;
 371         int ret;
 372         int prealloc;
 373         bool retry = false;
 374
 375         path = btrfs_alloc_path();
 376         if (!path)
 377                 return -ENOMEM;
 378 again:
 379         inode = lookup_free_ino_inode(root, path);
 380         if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
 381                 ret = PTR_ERR(inode);
 382                 goto out;
 383         }
 384
 385         if (IS_ERR(inode)) {
 386                 BUG_ON(retry);
 387                 retry = true;
 388
 389                 ret = create_free_ino_inode(root, trans, path);
 390                 if (ret)
 391                         goto out;
 392                 goto again;
 393         }
 394
 395         BTRFS_I(inode)->generation = 0;
 396         ret = btrfs_update_inode(trans, root, inode);
 397         WARN_ON(ret);
 398
 399         if (i_size_read(inode) > 0) {
 400                 ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
 401                 if (ret)
 402                         goto out_put;
 403         }
 404
 405         spin_lock(&root->cache_lock);
 406         if (root->cached != BTRFS_CACHE_FINISHED) {
 407                 ret = -1;
 408                 spin_unlock(&root->cache_lock);
 409                 goto out_put;
 410         }
 411         spin_unlock(&root->cache_lock);
 412
 413         spin_lock(&ctl->tree_lock);
 414         prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
 415         prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
 416         prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
 417         spin_unlock(&ctl->tree_lock);
 418
 419         /* Just to make sure we have enough space */
 420         prealloc += 8 * PAGE_CACHE_SIZE;
 421
 422         ret = btrfs_check_data_free_space(inode, prealloc);
 423         if (ret)
 424                 goto out_put;
 425
 426         ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
 427                                               prealloc, prealloc, &alloc_hint);
 428         if (ret)
 429                 goto out_put;
 430         btrfs_free_reserved_data_space(inode, prealloc);
 431
 432 out_put:
 433         iput(inode);
 434 out:
 435         if (ret == 0)
 436                 ret = btrfs_write_out_ino_cache(root, trans, path);
 437
 438         btrfs_free_path(path);
 439         return ret;
 440 }
 441
 442 static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
 443 {
 444         struct btrfs_path *path;
 445         int ret;
 446         struct extent_buffer *l;
 447         struct btrfs_key search_key;
 448         struct btrfs_key found_key;
 449         int slot;
 450
 451         path = btrfs_alloc_path();
 452         if (!path)
 453                 return -ENOMEM;
 454
 455         search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
 456         search_key.type = -1;
 457         search_key.offset = (u64)-1;
 458         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
 459         if (ret < 0)
 460                 goto error;
 461         BUG_ON(ret == 0);
 462         if (path->slots[0] > 0) {
 463                 slot = path->slots[0] - 1;
 464                 l = path->nodes[0];
 465                 btrfs_item_key_to_cpu(l, &found_key, slot);
 466                 *objectid = max_t(u64, found_key.objectid,
 467                                   BTRFS_FIRST_FREE_OBJECTID - 1);
 468         } else {
 469                 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
 470         }
 471         ret = 0;
 472 error:
 473         btrfs_free_path(path);
 474         return ret;
 475 }
 476
 477 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
 478 {
 479         int ret;
 480         mutex_lock(&root->objectid_mutex);
 481
 482         if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
 483                 ret = btrfs_find_highest_objectid(root,
 484                                                   &root->highest_objectid);
 485                 if (ret)
 486                         goto out;
 487         }
 488
 489         if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
 490                 ret = -ENOSPC;
 491                 goto out;
 492         }
 493
 494         *objectid = ++root->highest_objectid;
 495         ret = 0;
 496 out:
 497         mutex_unlock(&root->objectid_mutex);
 498         return ret;
 499 }