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(root, 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
 141         spin_lock(&root->cache_lock);
 142         if (root->cached != BTRFS_CACHE_NO) {
 143                 spin_unlock(&root->cache_lock);
 144                 return;
 145         }
 146
 147         root->cached = BTRFS_CACHE_STARTED;
 148         spin_unlock(&root->cache_lock);
 149
 150         tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
 151                           root->root_key.objectid);
 152         BUG_ON(IS_ERR(tsk));
 153 }
 154
 155 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
 156 {
 157 again:
 158         *objectid = btrfs_find_ino_for_alloc(root);
 159
 160         if (*objectid != 0)
 161                 return 0;
 162
 163         start_caching(root);
 164
 165         wait_event(root->cache_wait,
 166                    root->cached == BTRFS_CACHE_FINISHED ||
 167                    root->free_ino_ctl->free_space > 0);
 168
 169         if (root->cached == BTRFS_CACHE_FINISHED &&
 170             root->free_ino_ctl->free_space == 0)
 171                 return -ENOSPC;
 172         else
 173                 goto again;
 174 }
 175
 176 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
 177 {
 178         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 179         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 180 again:
 181         if (root->cached == BTRFS_CACHE_FINISHED) {
 182                 __btrfs_add_free_space(ctl, objectid, 1);
 183         } else {
 184                 /*
 185                  * If we are in the process of caching free ino chunks,
 186                  * to avoid adding the same inode number to the free_ino
 187                  * tree twice due to cross transaction, we'll leave it
 188                  * in the pinned tree until a transaction is committed
 189                  * or the caching work is done.
 190                  */
 191
 192                 mutex_lock(&root->fs_commit_mutex);
 193                 spin_lock(&root->cache_lock);
 194                 if (root->cached == BTRFS_CACHE_FINISHED) {
 195                         spin_unlock(&root->cache_lock);
 196                         mutex_unlock(&root->fs_commit_mutex);
 197                         goto again;
 198                 }
 199                 spin_unlock(&root->cache_lock);
 200
 201                 start_caching(root);
 202
 203                 if (objectid <= root->cache_progress)
 204                         __btrfs_add_free_space(ctl, objectid, 1);
 205                 else
 206                         __btrfs_add_free_space(pinned, objectid, 1);
 207
 208                 mutex_unlock(&root->fs_commit_mutex);
 209         }
 210 }
 211
 212 /*
 213  * When a transaction is committed, we'll move those inode numbers which
 214  * are smaller than root->cache_progress from pinned tree to free_ino tree,
 215  * and others will just be dropped, because the commit root we were
 216  * searching has changed.
 217  *
 218  * Must be called with root->fs_commit_mutex held
 219  */
 220 void btrfs_unpin_free_ino(struct btrfs_root *root)
 221 {
 222         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 223         struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
 224         struct btrfs_free_space *info;
 225         struct rb_node *n;
 226         u64 count;
 227
 228         while (1) {
 229                 n = rb_first(rbroot);
 230                 if (!n)
 231                         break;
 232
 233                 info = rb_entry(n, struct btrfs_free_space, offset_index);
 234                 BUG_ON(info->bitmap);
 235
 236                 if (info->offset > root->cache_progress)
 237                         goto free;
 238                 else if (info->offset + info->bytes > root->cache_progress)
 239                         count = root->cache_progress - info->offset + 1;
 240                 else
 241                         count = info->bytes;
 242
 243                 __btrfs_add_free_space(ctl, info->offset, count);
 244 free:
 245                 rb_erase(&info->offset_index, rbroot);
 246                 kfree(info);
 247         }
 248 }
 249
 250 #define INIT_THRESHOLD  (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
 251 #define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
 252
 253 /*
 254  * The goal is to keep the memory used by the free_ino tree won't
 255  * exceed the memory if we use bitmaps only.
 256  */
 257 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
 258 {
 259         struct btrfs_free_space *info;
 260         struct rb_node *n;
 261         int max_ino;
 262         int max_bitmaps;
 263
 264         n = rb_last(&ctl->free_space_offset);
 265         if (!n) {
 266                 ctl->extents_thresh = INIT_THRESHOLD;
 267                 return;
 268         }
 269         info = rb_entry(n, struct btrfs_free_space, offset_index);
 270
 271         /*
 272          * Find the maximum inode number in the filesystem. Note we
 273          * ignore the fact that this can be a bitmap, because we are
 274          * not doing precise calculation.
 275          */
 276         max_ino = info->bytes - 1;
 277
 278         max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
 279         if (max_bitmaps <= ctl->total_bitmaps) {
 280                 ctl->extents_thresh = 0;
 281                 return;
 282         }
 283
 284         ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
 285                                 PAGE_CACHE_SIZE / sizeof(*info);
 286 }
 287
 288 /*
 289  * We don't fall back to bitmap, if we are below the extents threshold
 290  * or this chunk of inode numbers is a big one.
 291  */
 292 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
 293                        struct btrfs_free_space *info)
 294 {
 295         if (ctl->free_extents < ctl->extents_thresh ||
 296             info->bytes > INODES_PER_BITMAP / 10)
 297                 return false;
 298
 299         return true;
 300 }
 301
 302 static struct btrfs_free_space_op free_ino_op = {
 303         .recalc_thresholds      = recalculate_thresholds,
 304         .use_bitmap             = use_bitmap,
 305 };
 306
 307 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
 308 {
 309 }
 310
 311 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
 312                               struct btrfs_free_space *info)
 313 {
 314         /*
 315          * We always use extents for two reasons:
 316          *
 317          * - The pinned tree is only used during the process of caching
 318          *   work.
 319          * - Make code simpler. See btrfs_unpin_free_ino().
 320          */
 321         return false;
 322 }
 323
 324 static struct btrfs_free_space_op pinned_free_ino_op = {
 325         .recalc_thresholds      = pinned_recalc_thresholds,
 326         .use_bitmap             = pinned_use_bitmap,
 327 };
 328
 329 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
 330 {
 331         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 332         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 333
 334         spin_lock_init(&ctl->tree_lock);
 335         ctl->unit = 1;
 336         ctl->start = 0;
 337         ctl->private = NULL;
 338         ctl->op = &free_ino_op;
 339
 340         /*
 341          * Initially we allow to use 16K of ram to cache chunks of
 342          * inode numbers before we resort to bitmaps. This is somewhat
 343          * arbitrary, but it will be adjusted in runtime.
 344          */
 345         ctl->extents_thresh = INIT_THRESHOLD;
 346
 347         spin_lock_init(&pinned->tree_lock);
 348         pinned->unit = 1;
 349         pinned->start = 0;
 350         pinned->private = NULL;
 351         pinned->extents_thresh = 0;
 352         pinned->op = &pinned_free_ino_op;
 353 }
 354
 355 static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
 356 {
 357         struct btrfs_path *path;
 358         int ret;
 359         struct extent_buffer *l;
 360         struct btrfs_key search_key;
 361         struct btrfs_key found_key;
 362         int slot;
 363
 364         path = btrfs_alloc_path();
 365         if (!path)
 366                 return -ENOMEM;
 367
 368         search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
 369         search_key.type = -1;
 370         search_key.offset = (u64)-1;
 371         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
 372         if (ret < 0)
 373                 goto error;
 374         BUG_ON(ret == 0);
 375         if (path->slots[0] > 0) {
 376                 slot = path->slots[0] - 1;
 377                 l = path->nodes[0];
 378                 btrfs_item_key_to_cpu(l, &found_key, slot);
 379                 *objectid = max_t(u64, found_key.objectid,
 380                                   BTRFS_FIRST_FREE_OBJECTID - 1);
 381         } else {
 382                 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
 383         }
 384         ret = 0;
 385 error:
 386         btrfs_free_path(path);
 387         return ret;
 388 }
 389
 390 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
 391 {
 392         int ret;
 393         mutex_lock(&root->objectid_mutex);
 394
 395         if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
 396                 ret = btrfs_find_highest_objectid(root,
 397                                                   &root->highest_objectid);
 398                 if (ret)
 399                         goto out;
 400         }
 401
 402         if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
 403                 ret = -ENOSPC;
 404                 goto out;
 405         }
 406
 407         *objectid = ++root->highest_objectid;
 408         ret = 0;
 409 out:
 410         mutex_unlock(&root->objectid_mutex);
 411         return ret;
 412 }