fs/btrfs/delayed-inode.c

   1 /*
   2  * Copyright (C) 2011 Fujitsu.  All rights reserved.
   3  * Written by Miao Xie <[email protected]>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public
   7  * License v2 as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public
  15  * License along with this program; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 021110-1307, USA.
  18  */
  19
  20 #include <linux/slab.h>
  21 #include "delayed-inode.h"
  22 #include "disk-io.h"
  23 #include "transaction.h"
  24
  25 #define BTRFS_DELAYED_WRITEBACK         512
  26 #define BTRFS_DELAYED_BACKGROUND        128
  27 #define BTRFS_DELAYED_BATCH             16
  28
  29 static struct kmem_cache *delayed_node_cache;
  30
  31 int __init btrfs_delayed_inode_init(void)
  32 {
  33         delayed_node_cache = kmem_cache_create("btrfs_delayed_node",
  34                                         sizeof(struct btrfs_delayed_node),
  35                                         0,
  36                                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
  37                                         NULL);
  38         if (!delayed_node_cache)
  39                 return -ENOMEM;
  40         return 0;
  41 }
  42
  43 void btrfs_delayed_inode_exit(void)
  44 {
  45         if (delayed_node_cache)
  46                 kmem_cache_destroy(delayed_node_cache);
  47 }
  48
  49 static inline void btrfs_init_delayed_node(
  50                                 struct btrfs_delayed_node *delayed_node,
  51                                 struct btrfs_root *root, u64 inode_id)
  52 {
  53         delayed_node->root = root;
  54         delayed_node->inode_id = inode_id;
  55         atomic_set(&delayed_node->refs, 0);
  56         delayed_node->count = 0;
  57         delayed_node->in_list = 0;
  58         delayed_node->inode_dirty = 0;
  59         delayed_node->ins_root = RB_ROOT;
  60         delayed_node->del_root = RB_ROOT;
  61         mutex_init(&delayed_node->mutex);
  62         delayed_node->index_cnt = 0;
  63         INIT_LIST_HEAD(&delayed_node->n_list);
  64         INIT_LIST_HEAD(&delayed_node->p_list);
  65         delayed_node->bytes_reserved = 0;
  66         memset(&delayed_node->inode_item, 0, sizeof(delayed_node->inode_item));
  67 }
  68
  69 static inline int btrfs_is_continuous_delayed_item(
  70                                         struct btrfs_delayed_item *item1,
  71                                         struct btrfs_delayed_item *item2)
  72 {
  73         if (item1->key.type == BTRFS_DIR_INDEX_KEY &&
  74             item1->key.objectid == item2->key.objectid &&
  75             item1->key.type == item2->key.type &&
  76             item1->key.offset + 1 == item2->key.offset)
  77                 return 1;
  78         return 0;
  79 }
  80
  81 static inline struct btrfs_delayed_root *btrfs_get_delayed_root(
  82                                                         struct btrfs_root *root)
  83 {
  84         return root->fs_info->delayed_root;
  85 }
  86
  87 static struct btrfs_delayed_node *btrfs_get_delayed_node(struct inode *inode)
  88 {
  89         struct btrfs_inode *btrfs_inode = BTRFS_I(inode);
  90         struct btrfs_root *root = btrfs_inode->root;
  91         u64 ino = btrfs_ino(inode);
  92         struct btrfs_delayed_node *node;
  93
  94         node = ACCESS_ONCE(btrfs_inode->delayed_node);
  95         if (node) {
  96                 atomic_inc(&node->refs);
  97                 return node;
  98         }
  99
 100         spin_lock(&root->inode_lock);
 101         node = radix_tree_lookup(&root->delayed_nodes_tree, ino);
 102         if (node) {
 103                 if (btrfs_inode->delayed_node) {
 104                         atomic_inc(&node->refs);        /* can be accessed */
 105                         BUG_ON(btrfs_inode->delayed_node != node);
 106                         spin_unlock(&root->inode_lock);
 107                         return node;
 108                 }
 109                 btrfs_inode->delayed_node = node;
 110                 atomic_inc(&node->refs);        /* can be accessed */
 111                 atomic_inc(&node->refs);        /* cached in the inode */
 112                 spin_unlock(&root->inode_lock);
 113                 return node;
 114         }
 115         spin_unlock(&root->inode_lock);
 116
 117         return NULL;
 118 }
 119
 120 /* Will return either the node or PTR_ERR(-ENOMEM) */
 121 static struct btrfs_delayed_node *btrfs_get_or_create_delayed_node(
 122                                                         struct inode *inode)
 123 {
 124         struct btrfs_delayed_node *node;
 125         struct btrfs_inode *btrfs_inode = BTRFS_I(inode);
 126         struct btrfs_root *root = btrfs_inode->root;
 127         u64 ino = btrfs_ino(inode);
 128         int ret;
 129
 130 again:
 131         node = btrfs_get_delayed_node(inode);
 132         if (node)
 133                 return node;
 134
 135         node = kmem_cache_alloc(delayed_node_cache, GFP_NOFS);
 136         if (!node)
 137                 return ERR_PTR(-ENOMEM);
 138         btrfs_init_delayed_node(node, root, ino);
 139
 140         atomic_inc(&node->refs);        /* cached in the btrfs inode */
 141         atomic_inc(&node->refs);        /* can be accessed */
 142
 143         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
 144         if (ret) {
 145                 kmem_cache_free(delayed_node_cache, node);
 146                 return ERR_PTR(ret);
 147         }
 148
 149         spin_lock(&root->inode_lock);
 150         ret = radix_tree_insert(&root->delayed_nodes_tree, ino, node);
 151         if (ret == -EEXIST) {
 152                 kmem_cache_free(delayed_node_cache, node);
 153                 spin_unlock(&root->inode_lock);
 154                 radix_tree_preload_end();
 155                 goto again;
 156         }
 157         btrfs_inode->delayed_node = node;
 158         spin_unlock(&root->inode_lock);
 159         radix_tree_preload_end();
 160
 161         return node;
 162 }
 163
 164 /*
 165  * Call it when holding delayed_node->mutex
 166  *
 167  * If mod = 1, add this node into the prepared list.
 168  */
 169 static void btrfs_queue_delayed_node(struct btrfs_delayed_root *root,
 170                                      struct btrfs_delayed_node *node,
 171                                      int mod)
 172 {
 173         spin_lock(&root->lock);
 174         if (node->in_list) {
 175                 if (!list_empty(&node->p_list))
 176                         list_move_tail(&node->p_list, &root->prepare_list);
 177                 else if (mod)
 178                         list_add_tail(&node->p_list, &root->prepare_list);
 179         } else {
 180                 list_add_tail(&node->n_list, &root->node_list);
 181                 list_add_tail(&node->p_list, &root->prepare_list);
 182                 atomic_inc(&node->refs);        /* inserted into list */
 183                 root->nodes++;
 184                 node->in_list = 1;
 185         }
 186         spin_unlock(&root->lock);
 187 }
 188
 189 /* Call it when holding delayed_node->mutex */
 190 static void btrfs_dequeue_delayed_node(struct btrfs_delayed_root *root,
 191                                        struct btrfs_delayed_node *node)
 192 {
 193         spin_lock(&root->lock);
 194         if (node->in_list) {
 195                 root->nodes--;
 196                 atomic_dec(&node->refs);        /* not in the list */
 197                 list_del_init(&node->n_list);
 198                 if (!list_empty(&node->p_list))
 199                         list_del_init(&node->p_list);
 200                 node->in_list = 0;
 201         }
 202         spin_unlock(&root->lock);
 203 }
 204
 205 static struct btrfs_delayed_node *btrfs_first_delayed_node(
 206                         struct btrfs_delayed_root *delayed_root)
 207 {
 208         struct list_head *p;
 209         struct btrfs_delayed_node *node = NULL;
 210
 211         spin_lock(&delayed_root->lock);
 212         if (list_empty(&delayed_root->node_list))
 213                 goto out;
 214
 215         p = delayed_root->node_list.next;
 216         node = list_entry(p, struct btrfs_delayed_node, n_list);
 217         atomic_inc(&node->refs);
 218 out:
 219         spin_unlock(&delayed_root->lock);
 220
 221         return node;
 222 }
 223
 224 static struct btrfs_delayed_node *btrfs_next_delayed_node(
 225                                                 struct btrfs_delayed_node *node)
 226 {
 227         struct btrfs_delayed_root *delayed_root;
 228         struct list_head *p;
 229         struct btrfs_delayed_node *next = NULL;
 230
 231         delayed_root = node->root->fs_info->delayed_root;
 232         spin_lock(&delayed_root->lock);
 233         if (!node->in_list) {   /* not in the list */
 234                 if (list_empty(&delayed_root->node_list))
 235                         goto out;
 236                 p = delayed_root->node_list.next;
 237         } else if (list_is_last(&node->n_list, &delayed_root->node_list))
 238                 goto out;
 239         else
 240                 p = node->n_list.next;
 241
 242         next = list_entry(p, struct btrfs_delayed_node, n_list);
 243         atomic_inc(&next->refs);
 244 out:
 245         spin_unlock(&delayed_root->lock);
 246
 247         return next;
 248 }
 249
 250 static void __btrfs_release_delayed_node(
 251                                 struct btrfs_delayed_node *delayed_node,
 252                                 int mod)
 253 {
 254         struct btrfs_delayed_root *delayed_root;
 255
 256         if (!delayed_node)
 257                 return;
 258
 259         delayed_root = delayed_node->root->fs_info->delayed_root;
 260
 261         mutex_lock(&delayed_node->mutex);
 262         if (delayed_node->count)
 263                 btrfs_queue_delayed_node(delayed_root, delayed_node, mod);
 264         else
 265                 btrfs_dequeue_delayed_node(delayed_root, delayed_node);
 266         mutex_unlock(&delayed_node->mutex);
 267
 268         if (atomic_dec_and_test(&delayed_node->refs)) {
 269                 struct btrfs_root *root = delayed_node->root;
 270                 spin_lock(&root->inode_lock);
 271                 if (atomic_read(&delayed_node->refs) == 0) {
 272                         radix_tree_delete(&root->delayed_nodes_tree,
 273                                           delayed_node->inode_id);
 274                         kmem_cache_free(delayed_node_cache, delayed_node);
 275                 }
 276                 spin_unlock(&root->inode_lock);
 277         }
 278 }
 279
 280 static inline void btrfs_release_delayed_node(struct btrfs_delayed_node *node)
 281 {
 282         __btrfs_release_delayed_node(node, 0);
 283 }
 284
 285 static struct btrfs_delayed_node *btrfs_first_prepared_delayed_node(
 286                                         struct btrfs_delayed_root *delayed_root)
 287 {
 288         struct list_head *p;
 289         struct btrfs_delayed_node *node = NULL;
 290
 291         spin_lock(&delayed_root->lock);
 292         if (list_empty(&delayed_root->prepare_list))
 293                 goto out;
 294
 295         p = delayed_root->prepare_list.next;
 296         list_del_init(p);
 297         node = list_entry(p, struct btrfs_delayed_node, p_list);
 298         atomic_inc(&node->refs);
 299 out:
 300         spin_unlock(&delayed_root->lock);
 301
 302         return node;
 303 }
 304
 305 static inline void btrfs_release_prepared_delayed_node(
 306                                         struct btrfs_delayed_node *node)
 307 {
 308         __btrfs_release_delayed_node(node, 1);
 309 }
 310
 311 static struct btrfs_delayed_item *btrfs_alloc_delayed_item(u32 data_len)
 312 {
 313         struct btrfs_delayed_item *item;
 314         item = kmalloc(sizeof(*item) + data_len, GFP_NOFS);
 315         if (item) {
 316                 item->data_len = data_len;
 317                 item->ins_or_del = 0;
 318                 item->bytes_reserved = 0;
 319                 item->delayed_node = NULL;
 320                 atomic_set(&item->refs, 1);
 321         }
 322         return item;
 323 }
 324
 325 /*
 326  * __btrfs_lookup_delayed_item - look up the delayed item by key
 327  * @delayed_node: pointer to the delayed node
 328  * @key:          the key to look up
 329  * @prev:         used to store the prev item if the right item isn't found
 330  * @next:         used to store the next item if the right item isn't found
 331  *
 332  * Note: if we don't find the right item, we will return the prev item and
 333  * the next item.
 334  */
 335 static struct btrfs_delayed_item *__btrfs_lookup_delayed_item(
 336                                 struct rb_root *root,
 337                                 struct btrfs_key *key,
 338                                 struct btrfs_delayed_item **prev,
 339                                 struct btrfs_delayed_item **next)
 340 {
 341         struct rb_node *node, *prev_node = NULL;
 342         struct btrfs_delayed_item *delayed_item = NULL;
 343         int ret = 0;
 344
 345         node = root->rb_node;
 346
 347         while (node) {
 348                 delayed_item = rb_entry(node, struct btrfs_delayed_item,
 349                                         rb_node);
 350                 prev_node = node;
 351                 ret = btrfs_comp_cpu_keys(&delayed_item->key, key);
 352                 if (ret < 0)
 353                         node = node->rb_right;
 354                 else if (ret > 0)
 355                         node = node->rb_left;
 356                 else
 357                         return delayed_item;
 358         }
 359
 360         if (prev) {
 361                 if (!prev_node)
 362                         *prev = NULL;
 363                 else if (ret < 0)
 364                         *prev = delayed_item;
 365                 else if ((node = rb_prev(prev_node)) != NULL) {
 366                         *prev = rb_entry(node, struct btrfs_delayed_item,
 367                                          rb_node);
 368                 } else
 369                         *prev = NULL;
 370         }
 371
 372         if (next) {
 373                 if (!prev_node)
 374                         *next = NULL;
 375                 else if (ret > 0)
 376                         *next = delayed_item;
 377                 else if ((node = rb_next(prev_node)) != NULL) {
 378                         *next = rb_entry(node, struct btrfs_delayed_item,
 379                                          rb_node);
 380                 } else
 381                         *next = NULL;
 382         }
 383         return NULL;
 384 }
 385
 386 static struct btrfs_delayed_item *__btrfs_lookup_delayed_insertion_item(
 387                                         struct btrfs_delayed_node *delayed_node,
 388                                         struct btrfs_key *key)
 389 {
 390         struct btrfs_delayed_item *item;
 391
 392         item = __btrfs_lookup_delayed_item(&delayed_node->ins_root, key,
 393                                            NULL, NULL);
 394         return item;
 395 }
 396
 397 static int __btrfs_add_delayed_item(struct btrfs_delayed_node *delayed_node,
 398                                     struct btrfs_delayed_item *ins,
 399                                     int action)
 400 {
 401         struct rb_node **p, *node;
 402         struct rb_node *parent_node = NULL;
 403         struct rb_root *root;
 404         struct btrfs_delayed_item *item;
 405         int cmp;
 406
 407         if (action == BTRFS_DELAYED_INSERTION_ITEM)
 408                 root = &delayed_node->ins_root;
 409         else if (action == BTRFS_DELAYED_DELETION_ITEM)
 410                 root = &delayed_node->del_root;
 411         else
 412                 BUG();
 413         p = &root->rb_node;
 414         node = &ins->rb_node;
 415
 416         while (*p) {
 417                 parent_node = *p;
 418                 item = rb_entry(parent_node, struct btrfs_delayed_item,
 419                                  rb_node);
 420
 421                 cmp = btrfs_comp_cpu_keys(&item->key, &ins->key);
 422                 if (cmp < 0)
 423                         p = &(*p)->rb_right;
 424                 else if (cmp > 0)
 425                         p = &(*p)->rb_left;
 426                 else
 427                         return -EEXIST;
 428         }
 429
 430         rb_link_node(node, parent_node, p);
 431         rb_insert_color(node, root);
 432         ins->delayed_node = delayed_node;
 433         ins->ins_or_del = action;
 434
 435         if (ins->key.type == BTRFS_DIR_INDEX_KEY &&
 436             action == BTRFS_DELAYED_INSERTION_ITEM &&
 437             ins->key.offset >= delayed_node->index_cnt)
 438                         delayed_node->index_cnt = ins->key.offset + 1;
 439
 440         delayed_node->count++;
 441         atomic_inc(&delayed_node->root->fs_info->delayed_root->items);
 442         return 0;
 443 }
 444
 445 static int __btrfs_add_delayed_insertion_item(struct btrfs_delayed_node *node,
 446                                               struct btrfs_delayed_item *item)
 447 {
 448         return __btrfs_add_delayed_item(node, item,
 449                                         BTRFS_DELAYED_INSERTION_ITEM);
 450 }
 451
 452 static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node,
 453                                              struct btrfs_delayed_item *item)
 454 {
 455         return __btrfs_add_delayed_item(node, item,
 456                                         BTRFS_DELAYED_DELETION_ITEM);
 457 }
 458
 459 static void finish_one_item(struct btrfs_delayed_root *delayed_root)
 460 {
 461         int seq = atomic_inc_return(&delayed_root->items_seq);
 462         if ((atomic_dec_return(&delayed_root->items) <
 463             BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0) &&
 464             waitqueue_active(&delayed_root->wait))
 465                 wake_up(&delayed_root->wait);
 466 }
 467
 468 static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
 469 {
 470         struct rb_root *root;
 471         struct btrfs_delayed_root *delayed_root;
 472
 473         delayed_root = delayed_item->delayed_node->root->fs_info->delayed_root;
 474
 475         BUG_ON(!delayed_root);
 476         BUG_ON(delayed_item->ins_or_del != BTRFS_DELAYED_DELETION_ITEM &&
 477                delayed_item->ins_or_del != BTRFS_DELAYED_INSERTION_ITEM);
 478
 479         if (delayed_item->ins_or_del == BTRFS_DELAYED_INSERTION_ITEM)
 480                 root = &delayed_item->delayed_node->ins_root;
 481         else
 482                 root = &delayed_item->delayed_node->del_root;
 483
 484         rb_erase(&delayed_item->rb_node, root);
 485         delayed_item->delayed_node->count--;
 486
 487         finish_one_item(delayed_root);
 488 }
 489
 490 static void btrfs_release_delayed_item(struct btrfs_delayed_item *item)
 491 {
 492         if (item) {
 493                 __btrfs_remove_delayed_item(item);
 494                 if (atomic_dec_and_test(&item->refs))
 495                         kfree(item);
 496         }
 497 }
 498
 499 static struct btrfs_delayed_item *__btrfs_first_delayed_insertion_item(
 500                                         struct btrfs_delayed_node *delayed_node)
 501 {
 502         struct rb_node *p;
 503         struct btrfs_delayed_item *item = NULL;
 504
 505         p = rb_first(&delayed_node->ins_root);
 506         if (p)
 507                 item = rb_entry(p, struct btrfs_delayed_item, rb_node);
 508
 509         return item;
 510 }
 511
 512 static struct btrfs_delayed_item *__btrfs_first_delayed_deletion_item(
 513                                         struct btrfs_delayed_node *delayed_node)
 514 {
 515         struct rb_node *p;
 516         struct btrfs_delayed_item *item = NULL;
 517
 518         p = rb_first(&delayed_node->del_root);
 519         if (p)
 520                 item = rb_entry(p, struct btrfs_delayed_item, rb_node);
 521
 522         return item;
 523 }
 524
 525 static struct btrfs_delayed_item *__btrfs_next_delayed_item(
 526                                                 struct btrfs_delayed_item *item)
 527 {
 528         struct rb_node *p;
 529         struct btrfs_delayed_item *next = NULL;
 530
 531         p = rb_next(&item->rb_node);
 532         if (p)
 533                 next = rb_entry(p, struct btrfs_delayed_item, rb_node);
 534
 535         return next;
 536 }
 537
 538 static int btrfs_delayed_item_reserve_metadata(struct btrfs_trans_handle *trans,
 539                                                struct btrfs_root *root,
 540                                                struct btrfs_delayed_item *item)
 541 {
 542         struct btrfs_block_rsv *src_rsv;
 543         struct btrfs_block_rsv *dst_rsv;
 544         u64 num_bytes;
 545         int ret;
 546
 547         if (!trans->bytes_reserved)
 548                 return 0;
 549
 550         src_rsv = trans->block_rsv;
 551         dst_rsv = &root->fs_info->delayed_block_rsv;
 552
 553         num_bytes = btrfs_calc_trans_metadata_size(root, 1);
 554         ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
 555         if (!ret) {
 556                 trace_btrfs_space_reservation(root->fs_info, "delayed_item",
 557                                               item->key.objectid,
 558                                               num_bytes, 1);
 559                 item->bytes_reserved = num_bytes;
 560         }
 561
 562         return ret;
 563 }
 564
 565 static void btrfs_delayed_item_release_metadata(struct btrfs_root *root,
 566                                                 struct btrfs_delayed_item *item)
 567 {
 568         struct btrfs_block_rsv *rsv;
 569
 570         if (!item->bytes_reserved)
 571                 return;
 572
 573         rsv = &root->fs_info->delayed_block_rsv;
 574         trace_btrfs_space_reservation(root->fs_info, "delayed_item",
 575                                       item->key.objectid, item->bytes_reserved,
 576                                       0);
 577         btrfs_block_rsv_release(root, rsv,
 578                                 item->bytes_reserved);
 579 }
 580
 581 static int btrfs_delayed_inode_reserve_metadata(
 582                                         struct btrfs_trans_handle *trans,
 583                                         struct btrfs_root *root,
 584                                         struct inode *inode,
 585                                         struct btrfs_delayed_node *node)
 586 {
 587         struct btrfs_block_rsv *src_rsv;
 588         struct btrfs_block_rsv *dst_rsv;
 589         u64 num_bytes;
 590         int ret;
 591         bool release = false;
 592
 593         src_rsv = trans->block_rsv;
 594         dst_rsv = &root->fs_info->delayed_block_rsv;
 595
 596         num_bytes = btrfs_calc_trans_metadata_size(root, 1);
 597
 598         /*
 599          * btrfs_dirty_inode will update the inode under btrfs_join_transaction
 600          * which doesn't reserve space for speed.  This is a problem since we
 601          * still need to reserve space for this update, so try to reserve the
 602          * space.
 603          *
 604          * Now if src_rsv == delalloc_block_rsv we'll let it just steal since
 605          * we're accounted for.
 606          */
 607         if (!src_rsv || (!trans->bytes_reserved &&
 608                          src_rsv->type != BTRFS_BLOCK_RSV_DELALLOC)) {
 609                 ret = btrfs_block_rsv_add(root, dst_rsv, num_bytes,
 610                                           BTRFS_RESERVE_NO_FLUSH);
 611                 /*
 612                  * Since we're under a transaction reserve_metadata_bytes could
 613                  * try to commit the transaction which will make it return
 614                  * EAGAIN to make us stop the transaction we have, so return
 615                  * ENOSPC instead so that btrfs_dirty_inode knows what to do.
 616                  */
 617                 if (ret == -EAGAIN)
 618                         ret = -ENOSPC;
 619                 if (!ret) {
 620                         node->bytes_reserved = num_bytes;
 621                         trace_btrfs_space_reservation(root->fs_info,
 622                                                       "delayed_inode",
 623                                                       btrfs_ino(inode),
 624                                                       num_bytes, 1);
 625                 }
 626                 return ret;
 627         } else if (src_rsv->type == BTRFS_BLOCK_RSV_DELALLOC) {
 628                 spin_lock(&BTRFS_I(inode)->lock);
 629                 if (test_and_clear_bit(BTRFS_INODE_DELALLOC_META_RESERVED,
 630                                        &BTRFS_I(inode)->runtime_flags)) {
 631                         spin_unlock(&BTRFS_I(inode)->lock);
 632                         release = true;
 633                         goto migrate;
 634                 }
 635                 spin_unlock(&BTRFS_I(inode)->lock);
 636
 637                 /* Ok we didn't have space pre-reserved.  This shouldn't happen
 638                  * too often but it can happen if we do delalloc to an existing
 639                  * inode which gets dirtied because of the time update, and then
 640                  * isn't touched again until after the transaction commits and
 641                  * then we try to write out the data.  First try to be nice and
 642                  * reserve something strictly for us.  If not be a pain and try
 643                  * to steal from the delalloc block rsv.
 644                  */
 645                 ret = btrfs_block_rsv_add(root, dst_rsv, num_bytes,
 646                                           BTRFS_RESERVE_NO_FLUSH);
 647                 if (!ret)
 648                         goto out;
 649
 650                 ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
 651                 if (!ret)
 652                         goto out;
 653
 654                 /*
 655                  * Ok this is a problem, let's just steal from the global rsv
 656                  * since this really shouldn't happen that often.
 657                  */
 658                 WARN_ON(1);
 659                 ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
 660                                               dst_rsv, num_bytes);
 661                 goto out;
 662         }
 663
 664 migrate:
 665         ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
 666
 667 out:
 668         /*
 669          * Migrate only takes a reservation, it doesn't touch the size of the
 670          * block_rsv.  This is to simplify people who don't normally have things
 671          * migrated from their block rsv.  If they go to release their
 672          * reservation, that will decrease the size as well, so if migrate
 673          * reduced size we'd end up with a negative size.  But for the
 674          * delalloc_meta_reserved stuff we will only know to drop 1 reservation,
 675          * but we could in fact do this reserve/migrate dance several times
 676          * between the time we did the original reservation and we'd clean it
 677          * up.  So to take care of this, release the space for the meta
 678          * reservation here.  I think it may be time for a documentation page on
 679          * how block rsvs. work.
 680          */
 681         if (!ret) {
 682                 trace_btrfs_space_reservation(root->fs_info, "delayed_inode",
 683                                               btrfs_ino(inode), num_bytes, 1);
 684                 node->bytes_reserved = num_bytes;
 685         }
 686
 687         if (release) {
 688                 trace_btrfs_space_reservation(root->fs_info, "delalloc",
 689                                               btrfs_ino(inode), num_bytes, 0);
 690                 btrfs_block_rsv_release(root, src_rsv, num_bytes);
 691         }
 692
 693         return ret;
 694 }
 695
 696 static void btrfs_delayed_inode_release_metadata(struct btrfs_root *root,
 697                                                 struct btrfs_delayed_node *node)
 698 {
 699         struct btrfs_block_rsv *rsv;
 700
 701         if (!node->bytes_reserved)
 702                 return;
 703
 704         rsv = &root->fs_info->delayed_block_rsv;
 705         trace_btrfs_space_reservation(root->fs_info, "delayed_inode",
 706                                       node->inode_id, node->bytes_reserved, 0);
 707         btrfs_block_rsv_release(root, rsv,
 708                                 node->bytes_reserved);
 709         node->bytes_reserved = 0;
 710 }
 711
 712 /*
 713  * This helper will insert some continuous items into the same leaf according
 714  * to the free space of the leaf.
 715  */
 716 static int btrfs_batch_insert_items(struct btrfs_root *root,
 717                                     struct btrfs_path *path,
 718                                     struct btrfs_delayed_item *item)
 719 {
 720         struct btrfs_delayed_item *curr, *next;
 721         int free_space;
 722         int total_data_size = 0, total_size = 0;
 723         struct extent_buffer *leaf;
 724         char *data_ptr;
 725         struct btrfs_key *keys;
 726         u32 *data_size;
 727         struct list_head head;
 728         int slot;
 729         int nitems;
 730         int i;
 731         int ret = 0;
 732
 733         BUG_ON(!path->nodes[0]);
 734
 735         leaf = path->nodes[0];
 736         free_space = btrfs_leaf_free_space(root, leaf);
 737         INIT_LIST_HEAD(&head);
 738
 739         next = item;
 740         nitems = 0;
 741
 742         /*
 743          * count the number of the continuous items that we can insert in batch
 744          */
 745         while (total_size + next->data_len + sizeof(struct btrfs_item) <=
 746                free_space) {
 747                 total_data_size += next->data_len;
 748                 total_size += next->data_len + sizeof(struct btrfs_item);
 749                 list_add_tail(&next->tree_list, &head);
 750                 nitems++;
 751
 752                 curr = next;
 753                 next = __btrfs_next_delayed_item(curr);
 754                 if (!next)
 755                         break;
 756
 757                 if (!btrfs_is_continuous_delayed_item(curr, next))
 758                         break;
 759         }
 760
 761         if (!nitems) {
 762                 ret = 0;
 763                 goto out;
 764         }
 765
 766         /*
 767          * we need allocate some memory space, but it might cause the task
 768          * to sleep, so we set all locked nodes in the path to blocking locks
 769          * first.
 770          */
 771         btrfs_set_path_blocking(path);
 772
 773         keys = kmalloc(sizeof(struct btrfs_key) * nitems, GFP_NOFS);
 774         if (!keys) {
 775                 ret = -ENOMEM;
 776                 goto out;
 777         }
 778
 779         data_size = kmalloc(sizeof(u32) * nitems, GFP_NOFS);
 780         if (!data_size) {
 781                 ret = -ENOMEM;
 782                 goto error;
 783         }
 784
 785         /* get keys of all the delayed items */
 786         i = 0;
 787         list_for_each_entry(next, &head, tree_list) {
 788                 keys[i] = next->key;
 789                 data_size[i] = next->data_len;
 790                 i++;
 791         }
 792
 793         /* reset all the locked nodes in the patch to spinning locks. */
 794         btrfs_clear_path_blocking(path, NULL, 0);
 795
 796         /* insert the keys of the items */
 797         setup_items_for_insert(root, path, keys, data_size,
 798                                total_data_size, total_size, nitems);
 799
 800         /* insert the dir index items */
 801         slot = path->slots[0];
 802         list_for_each_entry_safe(curr, next, &head, tree_list) {
 803                 data_ptr = btrfs_item_ptr(leaf, slot, char);
 804                 write_extent_buffer(leaf, &curr->data,
 805                                     (unsigned long)data_ptr,
 806                                     curr->data_len);
 807                 slot++;
 808
 809                 btrfs_delayed_item_release_metadata(root, curr);
 810
 811                 list_del(&curr->tree_list);
 812                 btrfs_release_delayed_item(curr);
 813         }
 814
 815 error:
 816         kfree(data_size);
 817         kfree(keys);
 818 out:
 819         return ret;
 820 }
 821
 822 /*
 823  * This helper can just do simple insertion that needn't extend item for new
 824  * data, such as directory name index insertion, inode insertion.
 825  */
 826 static int btrfs_insert_delayed_item(struct btrfs_trans_handle *trans,
 827                                      struct btrfs_root *root,
 828                                      struct btrfs_path *path,
 829                                      struct btrfs_delayed_item *delayed_item)
 830 {
 831         struct extent_buffer *leaf;
 832         char *ptr;
 833         int ret;
 834
 835         ret = btrfs_insert_empty_item(trans, root, path, &delayed_item->key,
 836                                       delayed_item->data_len);
 837         if (ret < 0 && ret != -EEXIST)
 838                 return ret;
 839
 840         leaf = path->nodes[0];
 841
 842         ptr = btrfs_item_ptr(leaf, path->slots[0], char);
 843
 844         write_extent_buffer(leaf, delayed_item->data, (unsigned long)ptr,
 845                             delayed_item->data_len);
 846         btrfs_mark_buffer_dirty(leaf);
 847
 848         btrfs_delayed_item_release_metadata(root, delayed_item);
 849         return 0;
 850 }
 851
 852 /*
 853  * we insert an item first, then if there are some continuous items, we try
 854  * to insert those items into the same leaf.
 855  */
 856 static int btrfs_insert_delayed_items(struct btrfs_trans_handle *trans,
 857                                       struct btrfs_path *path,
 858                                       struct btrfs_root *root,
 859                                       struct btrfs_delayed_node *node)
 860 {
 861         struct btrfs_delayed_item *curr, *prev;
 862         int ret = 0;
 863
 864 do_again:
 865         mutex_lock(&node->mutex);
 866         curr = __btrfs_first_delayed_insertion_item(node);
 867         if (!curr)
 868                 goto insert_end;
 869
 870         ret = btrfs_insert_delayed_item(trans, root, path, curr);
 871         if (ret < 0) {
 872                 btrfs_release_path(path);
 873                 goto insert_end;
 874         }
 875
 876         prev = curr;
 877         curr = __btrfs_next_delayed_item(prev);
 878         if (curr && btrfs_is_continuous_delayed_item(prev, curr)) {
 879                 /* insert the continuous items into the same leaf */
 880                 path->slots[0]++;
 881                 btrfs_batch_insert_items(root, path, curr);
 882         }
 883         btrfs_release_delayed_item(prev);
 884         btrfs_mark_buffer_dirty(path->nodes[0]);
 885
 886         btrfs_release_path(path);
 887         mutex_unlock(&node->mutex);
 888         goto do_again;
 889
 890 insert_end:
 891         mutex_unlock(&node->mutex);
 892         return ret;
 893 }
 894
 895 static int btrfs_batch_delete_items(struct btrfs_trans_handle *trans,
 896                                     struct btrfs_root *root,
 897                                     struct btrfs_path *path,
 898                                     struct btrfs_delayed_item *item)
 899 {
 900         struct btrfs_delayed_item *curr, *next;
 901         struct extent_buffer *leaf;
 902         struct btrfs_key key;
 903         struct list_head head;
 904         int nitems, i, last_item;
 905         int ret = 0;
 906
 907         BUG_ON(!path->nodes[0]);
 908
 909         leaf = path->nodes[0];
 910
 911         i = path->slots[0];
 912         last_item = btrfs_header_nritems(leaf) - 1;
 913         if (i > last_item)
 914                 return -ENOENT; /* FIXME: Is errno suitable? */
 915
 916         next = item;
 917         INIT_LIST_HEAD(&head);
 918         btrfs_item_key_to_cpu(leaf, &key, i);
 919         nitems = 0;
 920         /*
 921          * count the number of the dir index items that we can delete in batch
 922          */
 923         while (btrfs_comp_cpu_keys(&next->key, &key) == 0) {
 924                 list_add_tail(&next->tree_list, &head);
 925                 nitems++;
 926
 927                 curr = next;
 928                 next = __btrfs_next_delayed_item(curr);
 929                 if (!next)
 930                         break;
 931
 932                 if (!btrfs_is_continuous_delayed_item(curr, next))
 933                         break;
 934
 935                 i++;
 936                 if (i > last_item)
 937                         break;
 938                 btrfs_item_key_to_cpu(leaf, &key, i);
 939         }
 940
 941         if (!nitems)
 942                 return 0;
 943
 944         ret = btrfs_del_items(trans, root, path, path->slots[0], nitems);
 945         if (ret)
 946                 goto out;
 947
 948         list_for_each_entry_safe(curr, next, &head, tree_list) {
 949                 btrfs_delayed_item_release_metadata(root, curr);
 950                 list_del(&curr->tree_list);
 951                 btrfs_release_delayed_item(curr);
 952         }
 953
 954 out:
 955         return ret;
 956 }
 957
 958 static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans,
 959                                       struct btrfs_path *path,
 960                                       struct btrfs_root *root,
 961                                       struct btrfs_delayed_node *node)
 962 {
 963         struct btrfs_delayed_item *curr, *prev;
 964         int ret = 0;
 965
 966 do_again:
 967         mutex_lock(&node->mutex);
 968         curr = __btrfs_first_delayed_deletion_item(node);
 969         if (!curr)
 970                 goto delete_fail;
 971
 972         ret = btrfs_search_slot(trans, root, &curr->key, path, -1, 1);
 973         if (ret < 0)
 974                 goto delete_fail;
 975         else if (ret > 0) {
 976                 /*
 977                  * can't find the item which the node points to, so this node
 978                  * is invalid, just drop it.
 979                  */
 980                 prev = curr;
 981                 curr = __btrfs_next_delayed_item(prev);
 982                 btrfs_release_delayed_item(prev);
 983                 ret = 0;
 984                 btrfs_release_path(path);
 985                 if (curr) {
 986                         mutex_unlock(&node->mutex);
 987                         goto do_again;
 988                 } else
 989                         goto delete_fail;
 990         }
 991
 992         btrfs_batch_delete_items(trans, root, path, curr);
 993         btrfs_release_path(path);
 994         mutex_unlock(&node->mutex);
 995         goto do_again;
 996
 997 delete_fail:
 998         btrfs_release_path(path);
 999         mutex_unlock(&node->mutex);
1000         return ret;
1001 }
1002
1003 static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
1004 {
1005         struct btrfs_delayed_root *delayed_root;
1006
1007         if (delayed_node && delayed_node->inode_dirty) {
1008                 BUG_ON(!delayed_node->root);
1009                 delayed_node->inode_dirty = 0;
1010                 delayed_node->count--;
1011
1012                 delayed_root = delayed_node->root->fs_info->delayed_root;
1013                 finish_one_item(delayed_root);
1014         }
1015 }
1016
1017 static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
1018                                         struct btrfs_root *root,
1019                                         struct btrfs_path *path,
1020                                         struct btrfs_delayed_node *node)
1021 {
1022         struct btrfs_key key;
1023         struct btrfs_inode_item *inode_item;
1024         struct extent_buffer *leaf;
1025         int ret;
1026
1027         key.objectid = node->inode_id;
1028         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
1029         key.offset = 0;
1030
1031         ret = btrfs_lookup_inode(trans, root, path, &key, 1);
1032         if (ret > 0) {
1033                 btrfs_release_path(path);
1034                 return -ENOENT;
1035         } else if (ret < 0) {
1036                 return ret;
1037         }
1038
1039         btrfs_unlock_up_safe(path, 1);
1040         leaf = path->nodes[0];
1041         inode_item = btrfs_item_ptr(leaf, path->slots[0],
1042                                     struct btrfs_inode_item);
1043         write_extent_buffer(leaf, &node->inode_item, (unsigned long)inode_item,
1044                             sizeof(struct btrfs_inode_item));
1045         btrfs_mark_buffer_dirty(leaf);
1046         btrfs_release_path(path);
1047
1048         btrfs_delayed_inode_release_metadata(root, node);
1049         btrfs_release_delayed_inode(node);
1050
1051         return 0;
1052 }
1053
1054 static inline int btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
1055                                              struct btrfs_root *root,
1056                                              struct btrfs_path *path,
1057                                              struct btrfs_delayed_node *node)
1058 {
1059         int ret;
1060
1061         mutex_lock(&node->mutex);
1062         if (!node->inode_dirty) {
1063                 mutex_unlock(&node->mutex);
1064                 return 0;
1065         }
1066
1067         ret = __btrfs_update_delayed_inode(trans, root, path, node);
1068         mutex_unlock(&node->mutex);
1069         return ret;
1070 }
1071
1072 static inline int
1073 __btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
1074                                    struct btrfs_path *path,
1075                                    struct btrfs_delayed_node *node)
1076 {
1077         int ret;
1078
1079         ret = btrfs_insert_delayed_items(trans, path, node->root, node);
1080         if (ret)
1081                 return ret;
1082
1083         ret = btrfs_delete_delayed_items(trans, path, node->root, node);
1084         if (ret)
1085                 return ret;
1086
1087         ret = btrfs_update_delayed_inode(trans, node->root, path, node);
1088         return ret;
1089 }
1090
1091 /*
1092  * Called when committing the transaction.
1093  * Returns 0 on success.
1094  * Returns < 0 on error and returns with an aborted transaction with any
1095  * outstanding delayed items cleaned up.
1096  */
1097 static int __btrfs_run_delayed_items(struct btrfs_trans_handle *trans,
1098                                      struct btrfs_root *root, int nr)
1099 {
1100         struct btrfs_delayed_root *delayed_root;
1101         struct btrfs_delayed_node *curr_node, *prev_node;
1102         struct btrfs_path *path;
1103         struct btrfs_block_rsv *block_rsv;
1104         int ret = 0;
1105         bool count = (nr > 0);
1106
1107         if (trans->aborted)
1108                 return -EIO;
1109
1110         path = btrfs_alloc_path();
1111         if (!path)
1112                 return -ENOMEM;
1113         path->leave_spinning = 1;
1114
1115         block_rsv = trans->block_rsv;
1116         trans->block_rsv = &root->fs_info->delayed_block_rsv;
1117
1118         delayed_root = btrfs_get_delayed_root(root);
1119
1120         curr_node = btrfs_first_delayed_node(delayed_root);
1121         while (curr_node && (!count || (count && nr--))) {
1122                 ret = __btrfs_commit_inode_delayed_items(trans, path,
1123                                                          curr_node);
1124                 if (ret) {
1125                         btrfs_release_delayed_node(curr_node);
1126                         curr_node = NULL;
1127                         btrfs_abort_transaction(trans, root, ret);
1128                         break;
1129                 }
1130
1131                 prev_node = curr_node;
1132                 curr_node = btrfs_next_delayed_node(curr_node);
1133                 btrfs_release_delayed_node(prev_node);
1134         }
1135
1136         if (curr_node)
1137                 btrfs_release_delayed_node(curr_node);
1138         btrfs_free_path(path);
1139         trans->block_rsv = block_rsv;
1140
1141         return ret;
1142 }
1143
1144 int btrfs_run_delayed_items(struct btrfs_trans_handle *trans,
1145                             struct btrfs_root *root)
1146 {
1147         return __btrfs_run_delayed_items(trans, root, -1);
1148 }
1149
1150 int btrfs_run_delayed_items_nr(struct btrfs_trans_handle *trans,
1151                                struct btrfs_root *root, int nr)
1152 {
1153         return __btrfs_run_delayed_items(trans, root, nr);
1154 }
1155
1156 int btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
1157                                      struct inode *inode)
1158 {
1159         struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);
1160         struct btrfs_path *path;
1161         struct btrfs_block_rsv *block_rsv;
1162         int ret;
1163
1164         if (!delayed_node)
1165                 return 0;
1166
1167         mutex_lock(&delayed_node->mutex);
1168         if (!delayed_node->count) {
1169                 mutex_unlock(&delayed_node->mutex);
1170                 btrfs_release_delayed_node(delayed_node);
1171                 return 0;
1172         }
1173         mutex_unlock(&delayed_node->mutex);
1174
1175         path = btrfs_alloc_path();
1176         if (!path)
1177                 return -ENOMEM;
1178         path->leave_spinning = 1;
1179
1180         block_rsv = trans->block_rsv;
1181         trans->block_rsv = &delayed_node->root->fs_info->delayed_block_rsv;
1182
1183         ret = __btrfs_commit_inode_delayed_items(trans, path, delayed_node);
1184
1185         btrfs_release_delayed_node(delayed_node);
1186         btrfs_free_path(path);
1187         trans->block_rsv = block_rsv;
1188
1189         return ret;
1190 }
1191
1192 int btrfs_commit_inode_delayed_inode(struct inode *inode)
1193 {
1194         struct btrfs_trans_handle *trans;
1195         struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);
1196         struct btrfs_path *path;
1197         struct btrfs_block_rsv *block_rsv;
1198         int ret;
1199
1200         if (!delayed_node)
1201                 return 0;
1202
1203         mutex_lock(&delayed_node->mutex);
1204         if (!delayed_node->inode_dirty) {
1205                 mutex_unlock(&delayed_node->mutex);
1206                 btrfs_release_delayed_node(delayed_node);
1207                 return 0;
1208         }
1209         mutex_unlock(&delayed_node->mutex);
1210
1211         trans = btrfs_join_transaction(delayed_node->root);
1212         if (IS_ERR(trans)) {
1213                 ret = PTR_ERR(trans);
1214                 goto out;
1215         }
1216
1217         path = btrfs_alloc_path();
1218         if (!path) {
1219                 ret = -ENOMEM;
1220                 goto trans_out;
1221         }
1222         path->leave_spinning = 1;
1223
1224         block_rsv = trans->block_rsv;
1225         trans->block_rsv = &delayed_node->root->fs_info->delayed_block_rsv;
1226
1227         mutex_lock(&delayed_node->mutex);
1228         if (delayed_node->inode_dirty)
1229                 ret = __btrfs_update_delayed_inode(trans, delayed_node->root,
1230                                                    path, delayed_node);
1231         else
1232                 ret = 0;
1233         mutex_unlock(&delayed_node->mutex);
1234
1235         btrfs_free_path(path);
1236         trans->block_rsv = block_rsv;
1237 trans_out:
1238         btrfs_end_transaction(trans, delayed_node->root);
1239         btrfs_btree_balance_dirty(delayed_node->root);
1240 out:
1241         btrfs_release_delayed_node(delayed_node);
1242
1243         return ret;
1244 }
1245
1246 void btrfs_remove_delayed_node(struct inode *inode)
1247 {
1248         struct btrfs_delayed_node *delayed_node;
1249
1250         delayed_node = ACCESS_ONCE(BTRFS_I(inode)->delayed_node);
1251         if (!delayed_node)
1252                 return;
1253
1254         BTRFS_I(inode)->delayed_node = NULL;
1255         btrfs_release_delayed_node(delayed_node);
1256 }
1257
1258 struct btrfs_async_delayed_work {
1259         struct btrfs_delayed_root *delayed_root;
1260         int nr;
1261         struct btrfs_work work;
1262 };
1263
1264 static void btrfs_async_run_delayed_root(struct btrfs_work *work)
1265 {
1266         struct btrfs_async_delayed_work *async_work;
1267         struct btrfs_delayed_root *delayed_root;
1268         struct btrfs_trans_handle *trans;
1269         struct btrfs_path *path;
1270         struct btrfs_delayed_node *delayed_node = NULL;
1271         struct btrfs_root *root;
1272         struct btrfs_block_rsv *block_rsv;
1273         int total_done = 0;
1274
1275         async_work = container_of(work, struct btrfs_async_delayed_work, work);
1276         delayed_root = async_work->delayed_root;
1277
1278         path = btrfs_alloc_path();
1279         if (!path)
1280                 goto out;
1281
1282 again:
1283         if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND / 2)
1284                 goto free_path;
1285
1286         delayed_node = btrfs_first_prepared_delayed_node(delayed_root);
1287         if (!delayed_node)
1288                 goto free_path;
1289
1290         path->leave_spinning = 1;
1291         root = delayed_node->root;
1292
1293         trans = btrfs_join_transaction(root);
1294         if (IS_ERR(trans))
1295                 goto release_path;
1296
1297         block_rsv = trans->block_rsv;
1298         trans->block_rsv = &root->fs_info->delayed_block_rsv;
1299
1300         __btrfs_commit_inode_delayed_items(trans, path, delayed_node);
1301         /*
1302          * Maybe new delayed items have been inserted, so we need requeue
1303          * the work. Besides that, we must dequeue the empty delayed nodes
1304          * to avoid the race between delayed items balance and the worker.
1305          * The race like this:
1306          *      Task1                           Worker thread
1307          *                                      count == 0, needn't requeue
1308          *                                        also needn't insert the
1309          *                                        delayed node into prepare
1310          *                                        list again.
1311          *      add lots of delayed items
1312          *      queue the delayed node
1313          *        already in the list,
1314          *        and not in the prepare
1315          *        list, it means the delayed
1316          *        node is being dealt with
1317          *        by the worker.
1318          *      do delayed items balance
1319          *        the delayed node is being
1320          *        dealt with by the worker
1321          *        now, just wait.
1322          *                                      the worker goto idle.
1323          * Task1 will sleep until the transaction is commited.
1324          */
1325         mutex_lock(&delayed_node->mutex);
1326         btrfs_dequeue_delayed_node(root->fs_info->delayed_root, delayed_node);
1327         mutex_unlock(&delayed_node->mutex);
1328
1329         trans->block_rsv = block_rsv;
1330         btrfs_end_transaction_dmeta(trans, root);
1331         btrfs_btree_balance_dirty_nodelay(root);
1332
1333 release_path:
1334         btrfs_release_path(path);
1335         total_done++;
1336
1337         btrfs_release_prepared_delayed_node(delayed_node);
1338         if (async_work->nr == 0 || total_done < async_work->nr)
1339                 goto again;
1340
1341 free_path:
1342         btrfs_free_path(path);
1343 out:
1344         wake_up(&delayed_root->wait);
1345         kfree(async_work);
1346 }
1347
1348
1349 static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root,
1350                                      struct btrfs_root *root, int nr)
1351 {
1352         struct btrfs_async_delayed_work *async_work;
1353
1354         if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
1355                 return 0;
1356
1357         async_work = kmalloc(sizeof(*async_work), GFP_NOFS);
1358         if (!async_work)
1359                 return -ENOMEM;
1360
1361         async_work->delayed_root = delayed_root;
1362         async_work->work.func = btrfs_async_run_delayed_root;
1363         async_work->work.flags = 0;
1364         async_work->nr = nr;
1365
1366         btrfs_queue_worker(&root->fs_info->delayed_workers, &async_work->work);
1367         return 0;
1368 }
1369
1370 void btrfs_assert_delayed_root_empty(struct btrfs_root *root)
1371 {
1372         struct btrfs_delayed_root *delayed_root;
1373         delayed_root = btrfs_get_delayed_root(root);
1374         WARN_ON(btrfs_first_delayed_node(delayed_root));
1375 }
1376
1377 static int refs_newer(struct btrfs_delayed_root *delayed_root,
1378                       int seq, int count)
1379 {
1380         int val = atomic_read(&delayed_root->items_seq);
1381
1382         if (val < seq || val >= seq + count)
1383                 return 1;
1384         return 0;
1385 }
1386
1387 void btrfs_balance_delayed_items(struct btrfs_root *root)
1388 {
1389         struct btrfs_delayed_root *delayed_root;
1390         int seq;
1391
1392         delayed_root = btrfs_get_delayed_root(root);
1393
1394         if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
1395                 return;
1396
1397         seq = atomic_read(&delayed_root->items_seq);
1398
1399         if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) {
1400                 int ret;
1401                 DEFINE_WAIT(__wait);
1402
1403                 ret = btrfs_wq_run_delayed_node(delayed_root, root, 0);
1404                 if (ret)
1405                         return;
1406
1407                 while (1) {
1408                         prepare_to_wait(&delayed_root->wait, &__wait,
1409                                         TASK_INTERRUPTIBLE);
1410
1411                         if (refs_newer(delayed_root, seq,
1412                                        BTRFS_DELAYED_BATCH) ||
1413                             atomic_read(&delayed_root->items) <
1414                             BTRFS_DELAYED_BACKGROUND) {
1415                                 break;
1416                         }
1417                         if (!signal_pending(current))
1418                                 schedule();
1419                         else
1420                                 break;
1421                 }
1422                 finish_wait(&delayed_root->wait, &__wait);
1423         }
1424
1425         btrfs_wq_run_delayed_node(delayed_root, root, BTRFS_DELAYED_BATCH);
1426 }
1427
1428 /* Will return 0 or -ENOMEM */
1429 int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,
1430                                    struct btrfs_root *root, const char *name,
1431                                    int name_len, struct inode *dir,
1432                                    struct btrfs_disk_key *disk_key, u8 type,
1433                                    u64 index)
1434 {
1435         struct btrfs_delayed_node *delayed_node;
1436         struct btrfs_delayed_item *delayed_item;
1437         struct btrfs_dir_item *dir_item;
1438         int ret;
1439
1440         delayed_node = btrfs_get_or_create_delayed_node(dir);
1441         if (IS_ERR(delayed_node))
1442                 return PTR_ERR(delayed_node);
1443
1444         delayed_item = btrfs_alloc_delayed_item(sizeof(*dir_item) + name_len);
1445         if (!delayed_item) {
1446                 ret = -ENOMEM;
1447                 goto release_node;
1448         }
1449
1450         delayed_item->key.objectid = btrfs_ino(dir);
1451         btrfs_set_key_type(&delayed_item->key, BTRFS_DIR_INDEX_KEY);
1452         delayed_item->key.offset = index;
1453
1454         dir_item = (struct btrfs_dir_item *)delayed_item->data;
1455         dir_item->location = *disk_key;
1456         dir_item->transid = cpu_to_le64(trans->transid);
1457         dir_item->data_len = 0;
1458         dir_item->name_len = cpu_to_le16(name_len);
1459         dir_item->type = type;
1460         memcpy((char *)(dir_item + 1), name, name_len);
1461
1462         ret = btrfs_delayed_item_reserve_metadata(trans, root, delayed_item);
1463         /*
1464          * we have reserved enough space when we start a new transaction,
1465          * so reserving metadata failure is impossible
1466          */
1467         BUG_ON(ret);
1468
1469
1470         mutex_lock(&delayed_node->mutex);
1471         ret = __btrfs_add_delayed_insertion_item(delayed_node, delayed_item);
1472         if (unlikely(ret)) {
1473                 printk(KERN_ERR "err add delayed dir index item(name: %s) into "
1474                                 "the insertion tree of the delayed node"
1475                                 "(root id: %llu, inode id: %llu, errno: %d)\n",
1476                                 name,
1477                                 (unsigned long long)delayed_node->root->objectid,
1478                                 (unsigned long long)delayed_node->inode_id,
1479                                 ret);
1480                 BUG();
1481         }
1482         mutex_unlock(&delayed_node->mutex);
1483
1484 release_node:
1485         btrfs_release_delayed_node(delayed_node);
1486         return ret;
1487 }
1488
1489 static int btrfs_delete_delayed_insertion_item(struct btrfs_root *root,
1490                                                struct btrfs_delayed_node *node,
1491                                                struct btrfs_key *key)
1492 {
1493         struct btrfs_delayed_item *item;
1494
1495         mutex_lock(&node->mutex);
1496         item = __btrfs_lookup_delayed_insertion_item(node, key);
1497         if (!item) {
1498                 mutex_unlock(&node->mutex);
1499                 return 1;
1500         }
1501
1502         btrfs_delayed_item_release_metadata(root, item);
1503         btrfs_release_delayed_item(item);
1504         mutex_unlock(&node->mutex);
1505         return 0;
1506 }
1507
1508 int btrfs_delete_delayed_dir_index(struct btrfs_trans_handle *trans,
1509                                    struct btrfs_root *root, struct inode *dir,
1510                                    u64 index)
1511 {
1512         struct btrfs_delayed_node *node;
1513         struct btrfs_delayed_item *item;
1514         struct btrfs_key item_key;
1515         int ret;
1516
1517         node = btrfs_get_or_create_delayed_node(dir);
1518         if (IS_ERR(node))
1519                 return PTR_ERR(node);
1520
1521         item_key.objectid = btrfs_ino(dir);
1522         btrfs_set_key_type(&item_key, BTRFS_DIR_INDEX_KEY);
1523         item_key.offset = index;
1524
1525         ret = btrfs_delete_delayed_insertion_item(root, node, &item_key);
1526         if (!ret)
1527                 goto end;
1528
1529         item = btrfs_alloc_delayed_item(0);
1530         if (!item) {
1531                 ret = -ENOMEM;
1532                 goto end;
1533         }
1534
1535         item->key = item_key;
1536
1537         ret = btrfs_delayed_item_reserve_metadata(trans, root, item);
1538         /*
1539          * we have reserved enough space when we start a new transaction,
1540          * so reserving metadata failure is impossible.
1541          */
1542         BUG_ON(ret);
1543
1544         mutex_lock(&node->mutex);
1545         ret = __btrfs_add_delayed_deletion_item(node, item);
1546         if (unlikely(ret)) {
1547                 printk(KERN_ERR "err add delayed dir index item(index: %llu) "
1548                                 "into the deletion tree of the delayed node"
1549                                 "(root id: %llu, inode id: %llu, errno: %d)\n",
1550                                 (unsigned long long)index,
1551                                 (unsigned long long)node->root->objectid,
1552                                 (unsigned long long)node->inode_id,
1553                                 ret);
1554                 BUG();
1555         }
1556         mutex_unlock(&node->mutex);
1557 end:
1558         btrfs_release_delayed_node(node);
1559         return ret;
1560 }
1561
1562 int btrfs_inode_delayed_dir_index_count(struct inode *inode)
1563 {
1564         struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);
1565
1566         if (!delayed_node)
1567                 return -ENOENT;
1568
1569         /*
1570          * Since we have held i_mutex of this directory, it is impossible that
1571          * a new directory index is added into the delayed node and index_cnt
1572          * is updated now. So we needn't lock the delayed node.
1573          */
1574         if (!delayed_node->index_cnt) {
1575                 btrfs_release_delayed_node(delayed_node);
1576                 return -EINVAL;
1577         }
1578
1579         BTRFS_I(inode)->index_cnt = delayed_node->index_cnt;
1580         btrfs_release_delayed_node(delayed_node);
1581         return 0;
1582 }
1583
1584 void btrfs_get_delayed_items(struct inode *inode, struct list_head *ins_list,
1585                              struct list_head *del_list)
1586 {
1587         struct btrfs_delayed_node *delayed_node;
1588         struct btrfs_delayed_item *item;
1589
1590         delayed_node = btrfs_get_delayed_node(inode);
1591         if (!delayed_node)
1592                 return;
1593
1594         mutex_lock(&delayed_node->mutex);
1595         item = __btrfs_first_delayed_insertion_item(delayed_node);
1596         while (item) {
1597                 atomic_inc(&item->refs);
1598                 list_add_tail(&item->readdir_list, ins_list);
1599                 item = __btrfs_next_delayed_item(item);
1600         }
1601
1602         item = __btrfs_first_delayed_deletion_item(delayed_node);
1603         while (item) {
1604                 atomic_inc(&item->refs);
1605                 list_add_tail(&item->readdir_list, del_list);
1606                 item = __btrfs_next_delayed_item(item);
1607         }
1608         mutex_unlock(&delayed_node->mutex);
1609         /*
1610          * This delayed node is still cached in the btrfs inode, so refs
1611          * must be > 1 now, and we needn't check it is going to be freed
1612          * or not.
1613          *
1614          * Besides that, this function is used to read dir, we do not
1615          * insert/delete delayed items in this period. So we also needn't
1616          * requeue or dequeue this delayed node.
1617          */
1618         atomic_dec(&delayed_node->refs);
1619 }
1620
1621 void btrfs_put_delayed_items(struct list_head *ins_list,
1622                              struct list_head *del_list)
1623 {
1624         struct btrfs_delayed_item *curr, *next;
1625
1626         list_for_each_entry_safe(curr, next, ins_list, readdir_list) {
1627                 list_del(&curr->readdir_list);
1628                 if (atomic_dec_and_test(&curr->refs))
1629                         kfree(curr);
1630         }
1631
1632         list_for_each_entry_safe(curr, next, del_list, readdir_list) {
1633                 list_del(&curr->readdir_list);
1634                 if (atomic_dec_and_test(&curr->refs))
1635                         kfree(curr);
1636         }
1637 }
1638
1639 int btrfs_should_delete_dir_index(struct list_head *del_list,
1640                                   u64 index)
1641 {
1642         struct btrfs_delayed_item *curr, *next;
1643         int ret;
1644
1645         if (list_empty(del_list))
1646                 return 0;
1647
1648         list_for_each_entry_safe(curr, next, del_list, readdir_list) {
1649                 if (curr->key.offset > index)
1650                         break;
1651
1652                 list_del(&curr->readdir_list);
1653                 ret = (curr->key.offset == index);
1654
1655                 if (atomic_dec_and_test(&curr->refs))
1656                         kfree(curr);
1657
1658                 if (ret)
1659                         return 1;
1660                 else
1661                         continue;
1662         }
1663         return 0;
1664 }
1665
1666 /*
1667  * btrfs_readdir_delayed_dir_index - read dir info stored in the delayed tree
1668  *
1669  */
1670 int btrfs_readdir_delayed_dir_index(struct dir_context *ctx,
1671                                     struct list_head *ins_list)
1672 {
1673         struct btrfs_dir_item *di;
1674         struct btrfs_delayed_item *curr, *next;
1675         struct btrfs_key location;
1676         char *name;
1677         int name_len;
1678         int over = 0;
1679         unsigned char d_type;
1680
1681         if (list_empty(ins_list))
1682                 return 0;
1683
1684         /*
1685          * Changing the data of the delayed item is impossible. So
1686          * we needn't lock them. And we have held i_mutex of the
1687          * directory, nobody can delete any directory indexes now.
1688          */
1689         list_for_each_entry_safe(curr, next, ins_list, readdir_list) {
1690                 list_del(&curr->readdir_list);
1691
1692                 if (curr->key.offset < ctx->pos) {
1693                         if (atomic_dec_and_test(&curr->refs))
1694                                 kfree(curr);
1695                         continue;
1696                 }
1697
1698                 ctx->pos = curr->key.offset;
1699
1700                 di = (struct btrfs_dir_item *)curr->data;
1701                 name = (char *)(di + 1);
1702                 name_len = le16_to_cpu(di->name_len);
1703
1704                 d_type = btrfs_filetype_table[di->type];
1705                 btrfs_disk_key_to_cpu(&location, &di->location);
1706
1707                 over = !dir_emit(ctx, name, name_len,
1708                                location.objectid, d_type);
1709
1710                 if (atomic_dec_and_test(&curr->refs))
1711                         kfree(curr);
1712
1713                 if (over)
1714                         return 1;
1715         }
1716         return 0;
1717 }
1718
1719 BTRFS_SETGET_STACK_FUNCS(stack_inode_generation, struct btrfs_inode_item,
1720                          generation, 64);
1721 BTRFS_SETGET_STACK_FUNCS(stack_inode_sequence, struct btrfs_inode_item,
1722                          sequence, 64);
1723 BTRFS_SETGET_STACK_FUNCS(stack_inode_transid, struct btrfs_inode_item,
1724                          transid, 64);
1725 BTRFS_SETGET_STACK_FUNCS(stack_inode_size, struct btrfs_inode_item, size, 64);
1726 BTRFS_SETGET_STACK_FUNCS(stack_inode_nbytes, struct btrfs_inode_item,
1727                          nbytes, 64);
1728 BTRFS_SETGET_STACK_FUNCS(stack_inode_block_group, struct btrfs_inode_item,
1729                          block_group, 64);
1730 BTRFS_SETGET_STACK_FUNCS(stack_inode_nlink, struct btrfs_inode_item, nlink, 32);
1731 BTRFS_SETGET_STACK_FUNCS(stack_inode_uid, struct btrfs_inode_item, uid, 32);
1732 BTRFS_SETGET_STACK_FUNCS(stack_inode_gid, struct btrfs_inode_item, gid, 32);
1733 BTRFS_SETGET_STACK_FUNCS(stack_inode_mode, struct btrfs_inode_item, mode, 32);
1734 BTRFS_SETGET_STACK_FUNCS(stack_inode_rdev, struct btrfs_inode_item, rdev, 64);
1735 BTRFS_SETGET_STACK_FUNCS(stack_inode_flags, struct btrfs_inode_item, flags, 64);
1736
1737 BTRFS_SETGET_STACK_FUNCS(stack_timespec_sec, struct btrfs_timespec, sec, 64);
1738 BTRFS_SETGET_STACK_FUNCS(stack_timespec_nsec, struct btrfs_timespec, nsec, 32);
1739
1740 static void fill_stack_inode_item(struct btrfs_trans_handle *trans,
1741                                   struct btrfs_inode_item *inode_item,
1742                                   struct inode *inode)
1743 {
1744         btrfs_set_stack_inode_uid(inode_item, i_uid_read(inode));
1745         btrfs_set_stack_inode_gid(inode_item, i_gid_read(inode));
1746         btrfs_set_stack_inode_size(inode_item, BTRFS_I(inode)->disk_i_size);
1747         btrfs_set_stack_inode_mode(inode_item, inode->i_mode);
1748         btrfs_set_stack_inode_nlink(inode_item, inode->i_nlink);
1749         btrfs_set_stack_inode_nbytes(inode_item, inode_get_bytes(inode));
1750         btrfs_set_stack_inode_generation(inode_item,
1751                                          BTRFS_I(inode)->generation);
1752         btrfs_set_stack_inode_sequence(inode_item, inode->i_version);
1753         btrfs_set_stack_inode_transid(inode_item, trans->transid);
1754         btrfs_set_stack_inode_rdev(inode_item, inode->i_rdev);
1755         btrfs_set_stack_inode_flags(inode_item, BTRFS_I(inode)->flags);
1756         btrfs_set_stack_inode_block_group(inode_item, 0);
1757
1758         btrfs_set_stack_timespec_sec(btrfs_inode_atime(inode_item),
1759                                      inode->i_atime.tv_sec);
1760         btrfs_set_stack_timespec_nsec(btrfs_inode_atime(inode_item),
1761                                       inode->i_atime.tv_nsec);
1762
1763         btrfs_set_stack_timespec_sec(btrfs_inode_mtime(inode_item),
1764                                      inode->i_mtime.tv_sec);
1765         btrfs_set_stack_timespec_nsec(btrfs_inode_mtime(inode_item),
1766                                       inode->i_mtime.tv_nsec);
1767
1768         btrfs_set_stack_timespec_sec(btrfs_inode_ctime(inode_item),
1769                                      inode->i_ctime.tv_sec);
1770         btrfs_set_stack_timespec_nsec(btrfs_inode_ctime(inode_item),
1771                                       inode->i_ctime.tv_nsec);
1772 }
1773
1774 int btrfs_fill_inode(struct inode *inode, u32 *rdev)
1775 {
1776         struct btrfs_delayed_node *delayed_node;
1777         struct btrfs_inode_item *inode_item;
1778         struct btrfs_timespec *tspec;
1779
1780         delayed_node = btrfs_get_delayed_node(inode);
1781         if (!delayed_node)
1782                 return -ENOENT;
1783
1784         mutex_lock(&delayed_node->mutex);
1785         if (!delayed_node->inode_dirty) {
1786                 mutex_unlock(&delayed_node->mutex);
1787                 btrfs_release_delayed_node(delayed_node);
1788                 return -ENOENT;
1789         }
1790
1791         inode_item = &delayed_node->inode_item;
1792
1793         i_uid_write(inode, btrfs_stack_inode_uid(inode_item));
1794         i_gid_write(inode, btrfs_stack_inode_gid(inode_item));
1795         btrfs_i_size_write(inode, btrfs_stack_inode_size(inode_item));
1796         inode->i_mode = btrfs_stack_inode_mode(inode_item);
1797         set_nlink(inode, btrfs_stack_inode_nlink(inode_item));
1798         inode_set_bytes(inode, btrfs_stack_inode_nbytes(inode_item));
1799         BTRFS_I(inode)->generation = btrfs_stack_inode_generation(inode_item);
1800         inode->i_version = btrfs_stack_inode_sequence(inode_item);
1801         inode->i_rdev = 0;
1802         *rdev = btrfs_stack_inode_rdev(inode_item);
1803         BTRFS_I(inode)->flags = btrfs_stack_inode_flags(inode_item);
1804
1805         tspec = btrfs_inode_atime(inode_item);
1806         inode->i_atime.tv_sec = btrfs_stack_timespec_sec(tspec);
1807         inode->i_atime.tv_nsec = btrfs_stack_timespec_nsec(tspec);
1808
1809         tspec = btrfs_inode_mtime(inode_item);
1810         inode->i_mtime.tv_sec = btrfs_stack_timespec_sec(tspec);
1811         inode->i_mtime.tv_nsec = btrfs_stack_timespec_nsec(tspec);
1812
1813         tspec = btrfs_inode_ctime(inode_item);
1814         inode->i_ctime.tv_sec = btrfs_stack_timespec_sec(tspec);
1815         inode->i_ctime.tv_nsec = btrfs_stack_timespec_nsec(tspec);
1816
1817         inode->i_generation = BTRFS_I(inode)->generation;
1818         BTRFS_I(inode)->index_cnt = (u64)-1;
1819
1820         mutex_unlock(&delayed_node->mutex);
1821         btrfs_release_delayed_node(delayed_node);
1822         return 0;
1823 }
1824
1825 int btrfs_delayed_update_inode(struct btrfs_trans_handle *trans,
1826                                struct btrfs_root *root, struct inode *inode)
1827 {
1828         struct btrfs_delayed_node *delayed_node;
1829         int ret = 0;
1830
1831         delayed_node = btrfs_get_or_create_delayed_node(inode);
1832         if (IS_ERR(delayed_node))
1833                 return PTR_ERR(delayed_node);
1834
1835         mutex_lock(&delayed_node->mutex);
1836         if (delayed_node->inode_dirty) {
1837                 fill_stack_inode_item(trans, &delayed_node->inode_item, inode);
1838                 goto release_node;
1839         }
1840
1841         ret = btrfs_delayed_inode_reserve_metadata(trans, root, inode,
1842                                                    delayed_node);
1843         if (ret)
1844                 goto release_node;
1845
1846         fill_stack_inode_item(trans, &delayed_node->inode_item, inode);
1847         delayed_node->inode_dirty = 1;
1848         delayed_node->count++;
1849         atomic_inc(&root->fs_info->delayed_root->items);
1850 release_node:
1851         mutex_unlock(&delayed_node->mutex);
1852         btrfs_release_delayed_node(delayed_node);
1853         return ret;
1854 }
1855
1856 static void __btrfs_kill_delayed_node(struct btrfs_delayed_node *delayed_node)
1857 {
1858         struct btrfs_root *root = delayed_node->root;
1859         struct btrfs_delayed_item *curr_item, *prev_item;
1860
1861         mutex_lock(&delayed_node->mutex);
1862         curr_item = __btrfs_first_delayed_insertion_item(delayed_node);
1863         while (curr_item) {
1864                 btrfs_delayed_item_release_metadata(root, curr_item);
1865                 prev_item = curr_item;
1866                 curr_item = __btrfs_next_delayed_item(prev_item);
1867                 btrfs_release_delayed_item(prev_item);
1868         }
1869
1870         curr_item = __btrfs_first_delayed_deletion_item(delayed_node);
1871         while (curr_item) {
1872                 btrfs_delayed_item_release_metadata(root, curr_item);
1873                 prev_item = curr_item;
1874                 curr_item = __btrfs_next_delayed_item(prev_item);
1875                 btrfs_release_delayed_item(prev_item);
1876         }
1877
1878         if (delayed_node->inode_dirty) {
1879                 btrfs_delayed_inode_release_metadata(root, delayed_node);
1880                 btrfs_release_delayed_inode(delayed_node);
1881         }
1882         mutex_unlock(&delayed_node->mutex);
1883 }
1884
1885 void btrfs_kill_delayed_inode_items(struct inode *inode)
1886 {
1887         struct btrfs_delayed_node *delayed_node;
1888
1889         delayed_node = btrfs_get_delayed_node(inode);
1890         if (!delayed_node)
1891                 return;
1892
1893         __btrfs_kill_delayed_node(delayed_node);
1894         btrfs_release_delayed_node(delayed_node);
1895 }
1896
1897 void btrfs_kill_all_delayed_nodes(struct btrfs_root *root)
1898 {
1899         u64 inode_id = 0;
1900         struct btrfs_delayed_node *delayed_nodes[8];
1901         int i, n;
1902
1903         while (1) {
1904                 spin_lock(&root->inode_lock);
1905                 n = radix_tree_gang_lookup(&root->delayed_nodes_tree,
1906                                            (void **)delayed_nodes, inode_id,
1907                                            ARRAY_SIZE(delayed_nodes));
1908                 if (!n) {
1909                         spin_unlock(&root->inode_lock);
1910                         break;
1911                 }
1912
1913                 inode_id = delayed_nodes[n - 1]->inode_id + 1;
1914
1915                 for (i = 0; i < n; i++)
1916                         atomic_inc(&delayed_nodes[i]->refs);
1917                 spin_unlock(&root->inode_lock);
1918
1919                 for (i = 0; i < n; i++) {
1920                         __btrfs_kill_delayed_node(delayed_nodes[i]);
1921                         btrfs_release_delayed_node(delayed_nodes[i]);
1922                 }
1923         }
1924 }
1925
1926 void btrfs_destroy_delayed_inodes(struct btrfs_root *root)
1927 {
1928         struct btrfs_delayed_root *delayed_root;
1929         struct btrfs_delayed_node *curr_node, *prev_node;
1930
1931         delayed_root = btrfs_get_delayed_root(root);
1932
1933         curr_node = btrfs_first_delayed_node(delayed_root);
1934         while (curr_node) {
1935                 __btrfs_kill_delayed_node(curr_node);
1936
1937                 prev_node = curr_node;
1938                 curr_node = btrfs_next_delayed_node(curr_node);
1939                 btrfs_release_delayed_node(prev_node);
1940         }
1941 }
1942