1 /* 2 * f2fs extent cache support 3 * 4 * Copyright (c) 2015 Motorola Mobility 5 * Copyright (c) 2015 Samsung Electronics 6 * Authors: Jaegeuk Kim <jaegeuk@kernel.org> 7 * Chao Yu <chao2.yu@samsung.com> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 */ 13 14 #include <linux/fs.h> 15 #include <linux/f2fs_fs.h> 16 17 #include "f2fs.h" 18 #include "node.h" 19 #include <trace/events/f2fs.h> 20 21 static struct kmem_cache *extent_tree_slab; 22 static struct kmem_cache *extent_node_slab; 23 24 static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi, 25 struct extent_tree *et, struct extent_info *ei, 26 struct rb_node *parent, struct rb_node **p) 27 { 28 struct extent_node *en; 29 30 en = kmem_cache_alloc(extent_node_slab, GFP_ATOMIC); 31 if (!en) 32 return NULL; 33 34 en->ei = *ei; 35 INIT_LIST_HEAD(&en->list); 36 en->et = et; 37 38 rb_link_node(&en->rb_node, parent, p); 39 rb_insert_color(&en->rb_node, &et->root); 40 atomic_inc(&et->node_cnt); 41 atomic_inc(&sbi->total_ext_node); 42 return en; 43 } 44 45 static void __detach_extent_node(struct f2fs_sb_info *sbi, 46 struct extent_tree *et, struct extent_node *en) 47 { 48 rb_erase(&en->rb_node, &et->root); 49 atomic_dec(&et->node_cnt); 50 atomic_dec(&sbi->total_ext_node); 51 52 if (et->cached_en == en) 53 et->cached_en = NULL; 54 kmem_cache_free(extent_node_slab, en); 55 } 56 57 /* 58 * Flow to release an extent_node: 59 * 1. list_del_init 60 * 2. __detach_extent_node 61 * 3. kmem_cache_free. 62 */ 63 static void __release_extent_node(struct f2fs_sb_info *sbi, 64 struct extent_tree *et, struct extent_node *en) 65 { 66 spin_lock(&sbi->extent_lock); 67 f2fs_bug_on(sbi, list_empty(&en->list)); 68 list_del_init(&en->list); 69 spin_unlock(&sbi->extent_lock); 70 71 __detach_extent_node(sbi, et, en); 72 } 73 74 static struct extent_tree *__grab_extent_tree(struct inode *inode) 75 { 76 struct f2fs_sb_info *sbi = F2FS_I_SB(inode); 77 struct extent_tree *et; 78 nid_t ino = inode->i_ino; 79 80 down_write(&sbi->extent_tree_lock); 81 et = radix_tree_lookup(&sbi->extent_tree_root, ino); 82 if (!et) { 83 et = f2fs_kmem_cache_alloc(extent_tree_slab, GFP_NOFS); 84 f2fs_radix_tree_insert(&sbi->extent_tree_root, ino, et); 85 memset(et, 0, sizeof(struct extent_tree)); 86 et->ino = ino; 87 et->root = RB_ROOT; 88 et->cached_en = NULL; 89 rwlock_init(&et->lock); 90 INIT_LIST_HEAD(&et->list); 91 atomic_set(&et->node_cnt, 0); 92 atomic_inc(&sbi->total_ext_tree); 93 } else { 94 atomic_dec(&sbi->total_zombie_tree); 95 list_del_init(&et->list); 96 } 97 up_write(&sbi->extent_tree_lock); 98 99 /* never died until evict_inode */ 100 F2FS_I(inode)->extent_tree = et; 101 102 return et; 103 } 104 105 static struct extent_node *__lookup_extent_tree(struct f2fs_sb_info *sbi, 106 struct extent_tree *et, unsigned int fofs) 107 { 108 struct rb_node *node = et->root.rb_node; 109 struct extent_node *en = et->cached_en; 110 111 if (en) { 112 struct extent_info *cei = &en->ei; 113 114 if (cei->fofs <= fofs && cei->fofs + cei->len > fofs) { 115 stat_inc_cached_node_hit(sbi); 116 return en; 117 } 118 } 119 120 while (node) { 121 en = rb_entry(node, struct extent_node, rb_node); 122 123 if (fofs < en->ei.fofs) { 124 node = node->rb_left; 125 } else if (fofs >= en->ei.fofs + en->ei.len) { 126 node = node->rb_right; 127 } else { 128 stat_inc_rbtree_node_hit(sbi); 129 return en; 130 } 131 } 132 return NULL; 133 } 134 135 static struct extent_node *__init_extent_tree(struct f2fs_sb_info *sbi, 136 struct extent_tree *et, struct extent_info *ei) 137 { 138 struct rb_node **p = &et->root.rb_node; 139 struct extent_node *en; 140 141 en = __attach_extent_node(sbi, et, ei, NULL, p); 142 if (!en) 143 return NULL; 144 145 et->largest = en->ei; 146 et->cached_en = en; 147 return en; 148 } 149 150 static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi, 151 struct extent_tree *et) 152 { 153 struct rb_node *node, *next; 154 struct extent_node *en; 155 unsigned int count = atomic_read(&et->node_cnt); 156 157 node = rb_first(&et->root); 158 while (node) { 159 next = rb_next(node); 160 en = rb_entry(node, struct extent_node, rb_node); 161 __release_extent_node(sbi, et, en); 162 node = next; 163 } 164 165 return count - atomic_read(&et->node_cnt); 166 } 167 168 static void __drop_largest_extent(struct inode *inode, 169 pgoff_t fofs, unsigned int len) 170 { 171 struct extent_info *largest = &F2FS_I(inode)->extent_tree->largest; 172 173 if (fofs < largest->fofs + largest->len && fofs + len > largest->fofs) 174 largest->len = 0; 175 } 176 177 /* return true, if inode page is changed */ 178 bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext) 179 { 180 struct f2fs_sb_info *sbi = F2FS_I_SB(inode); 181 struct extent_tree *et; 182 struct extent_node *en; 183 struct extent_info ei; 184 185 if (!f2fs_may_extent_tree(inode)) { 186 /* drop largest extent */ 187 if (i_ext && i_ext->len) { 188 i_ext->len = 0; 189 return true; 190 } 191 return false; 192 } 193 194 et = __grab_extent_tree(inode); 195 196 if (!i_ext || !i_ext->len) 197 return false; 198 199 get_extent_info(&ei, i_ext); 200 201 write_lock(&et->lock); 202 if (atomic_read(&et->node_cnt)) 203 goto out; 204 205 en = __init_extent_tree(sbi, et, &ei); 206 if (en) { 207 spin_lock(&sbi->extent_lock); 208 list_add_tail(&en->list, &sbi->extent_list); 209 spin_unlock(&sbi->extent_lock); 210 } 211 out: 212 write_unlock(&et->lock); 213 return false; 214 } 215 216 static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs, 217 struct extent_info *ei) 218 { 219 struct f2fs_sb_info *sbi = F2FS_I_SB(inode); 220 struct extent_tree *et = F2FS_I(inode)->extent_tree; 221 struct extent_node *en; 222 bool ret = false; 223 224 f2fs_bug_on(sbi, !et); 225 226 trace_f2fs_lookup_extent_tree_start(inode, pgofs); 227 228 read_lock(&et->lock); 229 230 if (et->largest.fofs <= pgofs && 231 et->largest.fofs + et->largest.len > pgofs) { 232 *ei = et->largest; 233 ret = true; 234 stat_inc_largest_node_hit(sbi); 235 goto out; 236 } 237 238 en = __lookup_extent_tree(sbi, et, pgofs); 239 if (en) { 240 *ei = en->ei; 241 spin_lock(&sbi->extent_lock); 242 if (!list_empty(&en->list)) { 243 list_move_tail(&en->list, &sbi->extent_list); 244 et->cached_en = en; 245 } 246 spin_unlock(&sbi->extent_lock); 247 ret = true; 248 } 249 out: 250 stat_inc_total_hit(sbi); 251 read_unlock(&et->lock); 252 253 trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei); 254 return ret; 255 } 256 257 258 /* 259 * lookup extent at @fofs, if hit, return the extent 260 * if not, return NULL and 261 * @prev_ex: extent before fofs 262 * @next_ex: extent after fofs 263 * @insert_p: insert point for new extent at fofs 264 * in order to simpfy the insertion after. 265 * tree must stay unchanged between lookup and insertion. 266 */ 267 static struct extent_node *__lookup_extent_tree_ret(struct extent_tree *et, 268 unsigned int fofs, 269 struct extent_node **prev_ex, 270 struct extent_node **next_ex, 271 struct rb_node ***insert_p, 272 struct rb_node **insert_parent) 273 { 274 struct rb_node **pnode = &et->root.rb_node; 275 struct rb_node *parent = NULL, *tmp_node; 276 struct extent_node *en = et->cached_en; 277 278 *insert_p = NULL; 279 *insert_parent = NULL; 280 *prev_ex = NULL; 281 *next_ex = NULL; 282 283 if (RB_EMPTY_ROOT(&et->root)) 284 return NULL; 285 286 if (en) { 287 struct extent_info *cei = &en->ei; 288 289 if (cei->fofs <= fofs && cei->fofs + cei->len > fofs) 290 goto lookup_neighbors; 291 } 292 293 while (*pnode) { 294 parent = *pnode; 295 en = rb_entry(*pnode, struct extent_node, rb_node); 296 297 if (fofs < en->ei.fofs) 298 pnode = &(*pnode)->rb_left; 299 else if (fofs >= en->ei.fofs + en->ei.len) 300 pnode = &(*pnode)->rb_right; 301 else 302 goto lookup_neighbors; 303 } 304 305 *insert_p = pnode; 306 *insert_parent = parent; 307 308 en = rb_entry(parent, struct extent_node, rb_node); 309 tmp_node = parent; 310 if (parent && fofs > en->ei.fofs) 311 tmp_node = rb_next(parent); 312 *next_ex = tmp_node ? 313 rb_entry(tmp_node, struct extent_node, rb_node) : NULL; 314 315 tmp_node = parent; 316 if (parent && fofs < en->ei.fofs) 317 tmp_node = rb_prev(parent); 318 *prev_ex = tmp_node ? 319 rb_entry(tmp_node, struct extent_node, rb_node) : NULL; 320 return NULL; 321 322 lookup_neighbors: 323 if (fofs == en->ei.fofs) { 324 /* lookup prev node for merging backward later */ 325 tmp_node = rb_prev(&en->rb_node); 326 *prev_ex = tmp_node ? 327 rb_entry(tmp_node, struct extent_node, rb_node) : NULL; 328 } 329 if (fofs == en->ei.fofs + en->ei.len - 1) { 330 /* lookup next node for merging frontward later */ 331 tmp_node = rb_next(&en->rb_node); 332 *next_ex = tmp_node ? 333 rb_entry(tmp_node, struct extent_node, rb_node) : NULL; 334 } 335 return en; 336 } 337 338 static struct extent_node *__try_merge_extent_node(struct f2fs_sb_info *sbi, 339 struct extent_tree *et, struct extent_info *ei, 340 struct extent_node *prev_ex, 341 struct extent_node *next_ex) 342 { 343 struct extent_node *en = NULL; 344 345 if (prev_ex && __is_back_mergeable(ei, &prev_ex->ei)) { 346 prev_ex->ei.len += ei->len; 347 ei = &prev_ex->ei; 348 en = prev_ex; 349 } 350 351 if (next_ex && __is_front_mergeable(ei, &next_ex->ei)) { 352 if (en) 353 __release_extent_node(sbi, et, prev_ex); 354 next_ex->ei.fofs = ei->fofs; 355 next_ex->ei.blk = ei->blk; 356 next_ex->ei.len += ei->len; 357 en = next_ex; 358 } 359 360 if (!en) 361 return NULL; 362 363 __try_update_largest_extent(et, en); 364 365 spin_lock(&sbi->extent_lock); 366 if (!list_empty(&en->list)) { 367 list_move_tail(&en->list, &sbi->extent_list); 368 et->cached_en = en; 369 } 370 spin_unlock(&sbi->extent_lock); 371 return en; 372 } 373 374 static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi, 375 struct extent_tree *et, struct extent_info *ei, 376 struct rb_node **insert_p, 377 struct rb_node *insert_parent) 378 { 379 struct rb_node **p = &et->root.rb_node; 380 struct rb_node *parent = NULL; 381 struct extent_node *en = NULL; 382 383 if (insert_p && insert_parent) { 384 parent = insert_parent; 385 p = insert_p; 386 goto do_insert; 387 } 388 389 while (*p) { 390 parent = *p; 391 en = rb_entry(parent, struct extent_node, rb_node); 392 393 if (ei->fofs < en->ei.fofs) 394 p = &(*p)->rb_left; 395 else if (ei->fofs >= en->ei.fofs + en->ei.len) 396 p = &(*p)->rb_right; 397 else 398 f2fs_bug_on(sbi, 1); 399 } 400 do_insert: 401 en = __attach_extent_node(sbi, et, ei, parent, p); 402 if (!en) 403 return NULL; 404 405 __try_update_largest_extent(et, en); 406 407 /* update in global extent list */ 408 spin_lock(&sbi->extent_lock); 409 list_add_tail(&en->list, &sbi->extent_list); 410 et->cached_en = en; 411 spin_unlock(&sbi->extent_lock); 412 return en; 413 } 414 415 static unsigned int f2fs_update_extent_tree_range(struct inode *inode, 416 pgoff_t fofs, block_t blkaddr, unsigned int len) 417 { 418 struct f2fs_sb_info *sbi = F2FS_I_SB(inode); 419 struct extent_tree *et = F2FS_I(inode)->extent_tree; 420 struct extent_node *en = NULL, *en1 = NULL; 421 struct extent_node *prev_en = NULL, *next_en = NULL; 422 struct extent_info ei, dei, prev; 423 struct rb_node **insert_p = NULL, *insert_parent = NULL; 424 unsigned int end = fofs + len; 425 unsigned int pos = (unsigned int)fofs; 426 427 if (!et) 428 return false; 429 430 trace_f2fs_update_extent_tree_range(inode, fofs, blkaddr, len); 431 432 write_lock(&et->lock); 433 434 if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT)) { 435 write_unlock(&et->lock); 436 return false; 437 } 438 439 prev = et->largest; 440 dei.len = 0; 441 442 /* 443 * drop largest extent before lookup, in case it's already 444 * been shrunk from extent tree 445 */ 446 __drop_largest_extent(inode, fofs, len); 447 448 /* 1. lookup first extent node in range [fofs, fofs + len - 1] */ 449 en = __lookup_extent_tree_ret(et, fofs, &prev_en, &next_en, 450 &insert_p, &insert_parent); 451 if (!en) 452 en = next_en; 453 454 /* 2. invlidate all extent nodes in range [fofs, fofs + len - 1] */ 455 while (en && en->ei.fofs < end) { 456 unsigned int org_end; 457 int parts = 0; /* # of parts current extent split into */ 458 459 next_en = en1 = NULL; 460 461 dei = en->ei; 462 org_end = dei.fofs + dei.len; 463 f2fs_bug_on(sbi, pos >= org_end); 464 465 if (pos > dei.fofs && pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) { 466 en->ei.len = pos - en->ei.fofs; 467 prev_en = en; 468 parts = 1; 469 } 470 471 if (end < org_end && org_end - end >= F2FS_MIN_EXTENT_LEN) { 472 if (parts) { 473 set_extent_info(&ei, end, 474 end - dei.fofs + dei.blk, 475 org_end - end); 476 en1 = __insert_extent_tree(sbi, et, &ei, 477 NULL, NULL); 478 next_en = en1; 479 } else { 480 en->ei.fofs = end; 481 en->ei.blk += end - dei.fofs; 482 en->ei.len -= end - dei.fofs; 483 next_en = en; 484 } 485 parts++; 486 } 487 488 if (!next_en) { 489 struct rb_node *node = rb_next(&en->rb_node); 490 491 next_en = node ? 492 rb_entry(node, struct extent_node, rb_node) 493 : NULL; 494 } 495 496 if (parts) 497 __try_update_largest_extent(et, en); 498 else 499 __release_extent_node(sbi, et, en); 500 501 /* 502 * if original extent is split into zero or two parts, extent 503 * tree has been altered by deletion or insertion, therefore 504 * invalidate pointers regard to tree. 505 */ 506 if (parts != 1) { 507 insert_p = NULL; 508 insert_parent = NULL; 509 } 510 en = next_en; 511 } 512 513 /* 3. update extent in extent cache */ 514 if (blkaddr) { 515 516 set_extent_info(&ei, fofs, blkaddr, len); 517 if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en)) 518 __insert_extent_tree(sbi, et, &ei, 519 insert_p, insert_parent); 520 521 /* give up extent_cache, if split and small updates happen */ 522 if (dei.len >= 1 && 523 prev.len < F2FS_MIN_EXTENT_LEN && 524 et->largest.len < F2FS_MIN_EXTENT_LEN) { 525 et->largest.len = 0; 526 set_inode_flag(F2FS_I(inode), FI_NO_EXTENT); 527 } 528 } 529 530 if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT)) 531 __free_extent_tree(sbi, et); 532 533 write_unlock(&et->lock); 534 535 return !__is_extent_same(&prev, &et->largest); 536 } 537 538 unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink) 539 { 540 struct extent_tree *et, *next; 541 struct extent_node *en; 542 unsigned int node_cnt = 0, tree_cnt = 0; 543 int remained; 544 545 if (!test_opt(sbi, EXTENT_CACHE)) 546 return 0; 547 548 if (!atomic_read(&sbi->total_zombie_tree)) 549 goto free_node; 550 551 if (!down_write_trylock(&sbi->extent_tree_lock)) 552 goto out; 553 554 /* 1. remove unreferenced extent tree */ 555 list_for_each_entry_safe(et, next, &sbi->zombie_list, list) { 556 if (atomic_read(&et->node_cnt)) { 557 write_lock(&et->lock); 558 node_cnt += __free_extent_tree(sbi, et); 559 write_unlock(&et->lock); 560 } 561 f2fs_bug_on(sbi, atomic_read(&et->node_cnt)); 562 list_del_init(&et->list); 563 radix_tree_delete(&sbi->extent_tree_root, et->ino); 564 kmem_cache_free(extent_tree_slab, et); 565 atomic_dec(&sbi->total_ext_tree); 566 atomic_dec(&sbi->total_zombie_tree); 567 tree_cnt++; 568 569 if (node_cnt + tree_cnt >= nr_shrink) 570 goto unlock_out; 571 cond_resched(); 572 } 573 up_write(&sbi->extent_tree_lock); 574 575 free_node: 576 /* 2. remove LRU extent entries */ 577 if (!down_write_trylock(&sbi->extent_tree_lock)) 578 goto out; 579 580 remained = nr_shrink - (node_cnt + tree_cnt); 581 582 spin_lock(&sbi->extent_lock); 583 for (; remained > 0; remained--) { 584 if (list_empty(&sbi->extent_list)) 585 break; 586 en = list_first_entry(&sbi->extent_list, 587 struct extent_node, list); 588 et = en->et; 589 if (!write_trylock(&et->lock)) { 590 /* refresh this extent node's position in extent list */ 591 list_move_tail(&en->list, &sbi->extent_list); 592 continue; 593 } 594 595 list_del_init(&en->list); 596 spin_unlock(&sbi->extent_lock); 597 598 __detach_extent_node(sbi, et, en); 599 600 write_unlock(&et->lock); 601 node_cnt++; 602 spin_lock(&sbi->extent_lock); 603 } 604 spin_unlock(&sbi->extent_lock); 605 606 unlock_out: 607 up_write(&sbi->extent_tree_lock); 608 out: 609 trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt); 610 611 return node_cnt + tree_cnt; 612 } 613 614 unsigned int f2fs_destroy_extent_node(struct inode *inode) 615 { 616 struct f2fs_sb_info *sbi = F2FS_I_SB(inode); 617 struct extent_tree *et = F2FS_I(inode)->extent_tree; 618 unsigned int node_cnt = 0; 619 620 if (!et || !atomic_read(&et->node_cnt)) 621 return 0; 622 623 write_lock(&et->lock); 624 node_cnt = __free_extent_tree(sbi, et); 625 write_unlock(&et->lock); 626 627 return node_cnt; 628 } 629 630 void f2fs_destroy_extent_tree(struct inode *inode) 631 { 632 struct f2fs_sb_info *sbi = F2FS_I_SB(inode); 633 struct extent_tree *et = F2FS_I(inode)->extent_tree; 634 unsigned int node_cnt = 0; 635 636 if (!et) 637 return; 638 639 if (inode->i_nlink && !is_bad_inode(inode) && 640 atomic_read(&et->node_cnt)) { 641 down_write(&sbi->extent_tree_lock); 642 list_add_tail(&et->list, &sbi->zombie_list); 643 atomic_inc(&sbi->total_zombie_tree); 644 up_write(&sbi->extent_tree_lock); 645 return; 646 } 647 648 /* free all extent info belong to this extent tree */ 649 node_cnt = f2fs_destroy_extent_node(inode); 650 651 /* delete extent tree entry in radix tree */ 652 down_write(&sbi->extent_tree_lock); 653 f2fs_bug_on(sbi, atomic_read(&et->node_cnt)); 654 radix_tree_delete(&sbi->extent_tree_root, inode->i_ino); 655 kmem_cache_free(extent_tree_slab, et); 656 atomic_dec(&sbi->total_ext_tree); 657 up_write(&sbi->extent_tree_lock); 658 659 F2FS_I(inode)->extent_tree = NULL; 660 661 trace_f2fs_destroy_extent_tree(inode, node_cnt); 662 } 663 664 bool f2fs_lookup_extent_cache(struct inode *inode, pgoff_t pgofs, 665 struct extent_info *ei) 666 { 667 if (!f2fs_may_extent_tree(inode)) 668 return false; 669 670 return f2fs_lookup_extent_tree(inode, pgofs, ei); 671 } 672 673 void f2fs_update_extent_cache(struct dnode_of_data *dn) 674 { 675 pgoff_t fofs; 676 block_t blkaddr; 677 678 if (!f2fs_may_extent_tree(dn->inode)) 679 return; 680 681 if (dn->data_blkaddr == NEW_ADDR) 682 blkaddr = NULL_ADDR; 683 else 684 blkaddr = dn->data_blkaddr; 685 686 fofs = start_bidx_of_node(ofs_of_node(dn->node_page), dn->inode) + 687 dn->ofs_in_node; 688 689 if (f2fs_update_extent_tree_range(dn->inode, fofs, blkaddr, 1)) 690 sync_inode_page(dn); 691 } 692 693 void f2fs_update_extent_cache_range(struct dnode_of_data *dn, 694 pgoff_t fofs, block_t blkaddr, unsigned int len) 695 696 { 697 if (!f2fs_may_extent_tree(dn->inode)) 698 return; 699 700 if (f2fs_update_extent_tree_range(dn->inode, fofs, blkaddr, len)) 701 sync_inode_page(dn); 702 } 703 704 void init_extent_cache_info(struct f2fs_sb_info *sbi) 705 { 706 INIT_RADIX_TREE(&sbi->extent_tree_root, GFP_NOIO); 707 init_rwsem(&sbi->extent_tree_lock); 708 INIT_LIST_HEAD(&sbi->extent_list); 709 spin_lock_init(&sbi->extent_lock); 710 atomic_set(&sbi->total_ext_tree, 0); 711 INIT_LIST_HEAD(&sbi->zombie_list); 712 atomic_set(&sbi->total_zombie_tree, 0); 713 atomic_set(&sbi->total_ext_node, 0); 714 } 715 716 int __init create_extent_cache(void) 717 { 718 extent_tree_slab = f2fs_kmem_cache_create("f2fs_extent_tree", 719 sizeof(struct extent_tree)); 720 if (!extent_tree_slab) 721 return -ENOMEM; 722 extent_node_slab = f2fs_kmem_cache_create("f2fs_extent_node", 723 sizeof(struct extent_node)); 724 if (!extent_node_slab) { 725 kmem_cache_destroy(extent_tree_slab); 726 return -ENOMEM; 727 } 728 return 0; 729 } 730 731 void destroy_extent_cache(void) 732 { 733 kmem_cache_destroy(extent_node_slab); 734 kmem_cache_destroy(extent_tree_slab); 735 } 736