linux/fs/ext4/extents_status.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  fs/ext4/extents_status.c
   4 *
   5 * Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
   6 * Modified by
   7 *      Allison Henderson <achender@linux.vnet.ibm.com>
   8 *      Hugh Dickins <hughd@google.com>
   9 *      Zheng Liu <wenqing.lz@taobao.com>
  10 *
  11 * Ext4 extents status tree core functions.
  12 */
  13#include <linux/list_sort.h>
  14#include <linux/proc_fs.h>
  15#include <linux/seq_file.h>
  16#include "ext4.h"
  17
  18#include <trace/events/ext4.h>
  19
  20/*
  21 * According to previous discussion in Ext4 Developer Workshop, we
  22 * will introduce a new structure called io tree to track all extent
  23 * status in order to solve some problems that we have met
  24 * (e.g. Reservation space warning), and provide extent-level locking.
  25 * Delay extent tree is the first step to achieve this goal.  It is
  26 * original built by Yongqiang Yang.  At that time it is called delay
  27 * extent tree, whose goal is only track delayed extents in memory to
  28 * simplify the implementation of fiemap and bigalloc, and introduce
  29 * lseek SEEK_DATA/SEEK_HOLE support.  That is why it is still called
  30 * delay extent tree at the first commit.  But for better understand
  31 * what it does, it has been rename to extent status tree.
  32 *
  33 * Step1:
  34 * Currently the first step has been done.  All delayed extents are
  35 * tracked in the tree.  It maintains the delayed extent when a delayed
  36 * allocation is issued, and the delayed extent is written out or
  37 * invalidated.  Therefore the implementation of fiemap and bigalloc
  38 * are simplified, and SEEK_DATA/SEEK_HOLE are introduced.
  39 *
  40 * The following comment describes the implemenmtation of extent
  41 * status tree and future works.
  42 *
  43 * Step2:
  44 * In this step all extent status are tracked by extent status tree.
  45 * Thus, we can first try to lookup a block mapping in this tree before
  46 * finding it in extent tree.  Hence, single extent cache can be removed
  47 * because extent status tree can do a better job.  Extents in status
  48 * tree are loaded on-demand.  Therefore, the extent status tree may not
  49 * contain all of the extents in a file.  Meanwhile we define a shrinker
  50 * to reclaim memory from extent status tree because fragmented extent
  51 * tree will make status tree cost too much memory.  written/unwritten/-
  52 * hole extents in the tree will be reclaimed by this shrinker when we
  53 * are under high memory pressure.  Delayed extents will not be
  54 * reclimed because fiemap, bigalloc, and seek_data/hole need it.
  55 */
  56
  57/*
  58 * Extent status tree implementation for ext4.
  59 *
  60 *
  61 * ==========================================================================
  62 * Extent status tree tracks all extent status.
  63 *
  64 * 1. Why we need to implement extent status tree?
  65 *
  66 * Without extent status tree, ext4 identifies a delayed extent by looking
  67 * up page cache, this has several deficiencies - complicated, buggy,
  68 * and inefficient code.
  69 *
  70 * FIEMAP, SEEK_HOLE/DATA, bigalloc, and writeout all need to know if a
  71 * block or a range of blocks are belonged to a delayed extent.
  72 *
  73 * Let us have a look at how they do without extent status tree.
  74 *   -- FIEMAP
  75 *      FIEMAP looks up page cache to identify delayed allocations from holes.
  76 *
  77 *   -- SEEK_HOLE/DATA
  78 *      SEEK_HOLE/DATA has the same problem as FIEMAP.
  79 *
  80 *   -- bigalloc
  81 *      bigalloc looks up page cache to figure out if a block is
  82 *      already under delayed allocation or not to determine whether
  83 *      quota reserving is needed for the cluster.
  84 *
  85 *   -- writeout
  86 *      Writeout looks up whole page cache to see if a buffer is
  87 *      mapped, If there are not very many delayed buffers, then it is
  88 *      time consuming.
  89 *
  90 * With extent status tree implementation, FIEMAP, SEEK_HOLE/DATA,
  91 * bigalloc and writeout can figure out if a block or a range of
  92 * blocks is under delayed allocation(belonged to a delayed extent) or
  93 * not by searching the extent tree.
  94 *
  95 *
  96 * ==========================================================================
  97 * 2. Ext4 extent status tree impelmentation
  98 *
  99 *   -- extent
 100 *      A extent is a range of blocks which are contiguous logically and
 101 *      physically.  Unlike extent in extent tree, this extent in ext4 is
 102 *      a in-memory struct, there is no corresponding on-disk data.  There
 103 *      is no limit on length of extent, so an extent can contain as many
 104 *      blocks as they are contiguous logically and physically.
 105 *
 106 *   -- extent status tree
 107 *      Every inode has an extent status tree and all allocation blocks
 108 *      are added to the tree with different status.  The extent in the
 109 *      tree are ordered by logical block no.
 110 *
 111 *   -- operations on a extent status tree
 112 *      There are three important operations on a delayed extent tree: find
 113 *      next extent, adding a extent(a range of blocks) and removing a extent.
 114 *
 115 *   -- race on a extent status tree
 116 *      Extent status tree is protected by inode->i_es_lock.
 117 *
 118 *   -- memory consumption
 119 *      Fragmented extent tree will make extent status tree cost too much
 120 *      memory.  Hence, we will reclaim written/unwritten/hole extents from
 121 *      the tree under a heavy memory pressure.
 122 *
 123 *
 124 * ==========================================================================
 125 * 3. Performance analysis
 126 *
 127 *   -- overhead
 128 *      1. There is a cache extent for write access, so if writes are
 129 *      not very random, adding space operaions are in O(1) time.
 130 *
 131 *   -- gain
 132 *      2. Code is much simpler, more readable, more maintainable and
 133 *      more efficient.
 134 *
 135 *
 136 * ==========================================================================
 137 * 4. TODO list
 138 *
 139 *   -- Refactor delayed space reservation
 140 *
 141 *   -- Extent-level locking
 142 */
 143
 144static struct kmem_cache *ext4_es_cachep;
 145
 146static int __es_insert_extent(struct inode *inode, struct extent_status *newes);
 147static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
 148                              ext4_lblk_t end);
 149static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan);
 150static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
 151                       struct ext4_inode_info *locked_ei);
 152
 153int __init ext4_init_es(void)
 154{
 155        ext4_es_cachep = kmem_cache_create("ext4_extent_status",
 156                                           sizeof(struct extent_status),
 157                                           0, (SLAB_RECLAIM_ACCOUNT), NULL);
 158        if (ext4_es_cachep == NULL)
 159                return -ENOMEM;
 160        return 0;
 161}
 162
 163void ext4_exit_es(void)
 164{
 165        kmem_cache_destroy(ext4_es_cachep);
 166}
 167
 168void ext4_es_init_tree(struct ext4_es_tree *tree)
 169{
 170        tree->root = RB_ROOT;
 171        tree->cache_es = NULL;
 172}
 173
 174#ifdef ES_DEBUG__
 175static void ext4_es_print_tree(struct inode *inode)
 176{
 177        struct ext4_es_tree *tree;
 178        struct rb_node *node;
 179
 180        printk(KERN_DEBUG "status extents for inode %lu:", inode->i_ino);
 181        tree = &EXT4_I(inode)->i_es_tree;
 182        node = rb_first(&tree->root);
 183        while (node) {
 184                struct extent_status *es;
 185                es = rb_entry(node, struct extent_status, rb_node);
 186                printk(KERN_DEBUG " [%u/%u) %llu %x",
 187                       es->es_lblk, es->es_len,
 188                       ext4_es_pblock(es), ext4_es_status(es));
 189                node = rb_next(node);
 190        }
 191        printk(KERN_DEBUG "\n");
 192}
 193#else
 194#define ext4_es_print_tree(inode)
 195#endif
 196
 197static inline ext4_lblk_t ext4_es_end(struct extent_status *es)
 198{
 199        BUG_ON(es->es_lblk + es->es_len < es->es_lblk);
 200        return es->es_lblk + es->es_len - 1;
 201}
 202
 203/*
 204 * search through the tree for an delayed extent with a given offset.  If
 205 * it can't be found, try to find next extent.
 206 */
 207static struct extent_status *__es_tree_search(struct rb_root *root,
 208                                              ext4_lblk_t lblk)
 209{
 210        struct rb_node *node = root->rb_node;
 211        struct extent_status *es = NULL;
 212
 213        while (node) {
 214                es = rb_entry(node, struct extent_status, rb_node);
 215                if (lblk < es->es_lblk)
 216                        node = node->rb_left;
 217                else if (lblk > ext4_es_end(es))
 218                        node = node->rb_right;
 219                else
 220                        return es;
 221        }
 222
 223        if (es && lblk < es->es_lblk)
 224                return es;
 225
 226        if (es && lblk > ext4_es_end(es)) {
 227                node = rb_next(&es->rb_node);
 228                return node ? rb_entry(node, struct extent_status, rb_node) :
 229                              NULL;
 230        }
 231
 232        return NULL;
 233}
 234
 235/*
 236 * ext4_es_find_delayed_extent_range: find the 1st delayed extent covering
 237 * @es->lblk if it exists, otherwise, the next extent after @es->lblk.
 238 *
 239 * @inode: the inode which owns delayed extents
 240 * @lblk: the offset where we start to search
 241 * @end: the offset where we stop to search
 242 * @es: delayed extent that we found
 243 */
 244void ext4_es_find_delayed_extent_range(struct inode *inode,
 245                                 ext4_lblk_t lblk, ext4_lblk_t end,
 246                                 struct extent_status *es)
 247{
 248        struct ext4_es_tree *tree = NULL;
 249        struct extent_status *es1 = NULL;
 250        struct rb_node *node;
 251
 252        BUG_ON(es == NULL);
 253        BUG_ON(end < lblk);
 254        trace_ext4_es_find_delayed_extent_range_enter(inode, lblk);
 255
 256        read_lock(&EXT4_I(inode)->i_es_lock);
 257        tree = &EXT4_I(inode)->i_es_tree;
 258
 259        /* find extent in cache firstly */
 260        es->es_lblk = es->es_len = es->es_pblk = 0;
 261        if (tree->cache_es) {
 262                es1 = tree->cache_es;
 263                if (in_range(lblk, es1->es_lblk, es1->es_len)) {
 264                        es_debug("%u cached by [%u/%u) %llu %x\n",
 265                                 lblk, es1->es_lblk, es1->es_len,
 266                                 ext4_es_pblock(es1), ext4_es_status(es1));
 267                        goto out;
 268                }
 269        }
 270
 271        es1 = __es_tree_search(&tree->root, lblk);
 272
 273out:
 274        if (es1 && !ext4_es_is_delayed(es1)) {
 275                while ((node = rb_next(&es1->rb_node)) != NULL) {
 276                        es1 = rb_entry(node, struct extent_status, rb_node);
 277                        if (es1->es_lblk > end) {
 278                                es1 = NULL;
 279                                break;
 280                        }
 281                        if (ext4_es_is_delayed(es1))
 282                                break;
 283                }
 284        }
 285
 286        if (es1 && ext4_es_is_delayed(es1)) {
 287                tree->cache_es = es1;
 288                es->es_lblk = es1->es_lblk;
 289                es->es_len = es1->es_len;
 290                es->es_pblk = es1->es_pblk;
 291        }
 292
 293        read_unlock(&EXT4_I(inode)->i_es_lock);
 294
 295        trace_ext4_es_find_delayed_extent_range_exit(inode, es);
 296}
 297
 298static void ext4_es_list_add(struct inode *inode)
 299{
 300        struct ext4_inode_info *ei = EXT4_I(inode);
 301        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 302
 303        if (!list_empty(&ei->i_es_list))
 304                return;
 305
 306        spin_lock(&sbi->s_es_lock);
 307        if (list_empty(&ei->i_es_list)) {
 308                list_add_tail(&ei->i_es_list, &sbi->s_es_list);
 309                sbi->s_es_nr_inode++;
 310        }
 311        spin_unlock(&sbi->s_es_lock);
 312}
 313
 314static void ext4_es_list_del(struct inode *inode)
 315{
 316        struct ext4_inode_info *ei = EXT4_I(inode);
 317        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 318
 319        spin_lock(&sbi->s_es_lock);
 320        if (!list_empty(&ei->i_es_list)) {
 321                list_del_init(&ei->i_es_list);
 322                sbi->s_es_nr_inode--;
 323                WARN_ON_ONCE(sbi->s_es_nr_inode < 0);
 324        }
 325        spin_unlock(&sbi->s_es_lock);
 326}
 327
 328static struct extent_status *
 329ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
 330                     ext4_fsblk_t pblk)
 331{
 332        struct extent_status *es;
 333        es = kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC);
 334        if (es == NULL)
 335                return NULL;
 336        es->es_lblk = lblk;
 337        es->es_len = len;
 338        es->es_pblk = pblk;
 339
 340        /*
 341         * We don't count delayed extent because we never try to reclaim them
 342         */
 343        if (!ext4_es_is_delayed(es)) {
 344                if (!EXT4_I(inode)->i_es_shk_nr++)
 345                        ext4_es_list_add(inode);
 346                percpu_counter_inc(&EXT4_SB(inode->i_sb)->
 347                                        s_es_stats.es_stats_shk_cnt);
 348        }
 349
 350        EXT4_I(inode)->i_es_all_nr++;
 351        percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
 352
 353        return es;
 354}
 355
 356static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
 357{
 358        EXT4_I(inode)->i_es_all_nr--;
 359        percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
 360
 361        /* Decrease the shrink counter when this es is not delayed */
 362        if (!ext4_es_is_delayed(es)) {
 363                BUG_ON(EXT4_I(inode)->i_es_shk_nr == 0);
 364                if (!--EXT4_I(inode)->i_es_shk_nr)
 365                        ext4_es_list_del(inode);
 366                percpu_counter_dec(&EXT4_SB(inode->i_sb)->
 367                                        s_es_stats.es_stats_shk_cnt);
 368        }
 369
 370        kmem_cache_free(ext4_es_cachep, es);
 371}
 372
 373/*
 374 * Check whether or not two extents can be merged
 375 * Condition:
 376 *  - logical block number is contiguous
 377 *  - physical block number is contiguous
 378 *  - status is equal
 379 */
 380static int ext4_es_can_be_merged(struct extent_status *es1,
 381                                 struct extent_status *es2)
 382{
 383        if (ext4_es_type(es1) != ext4_es_type(es2))
 384                return 0;
 385
 386        if (((__u64) es1->es_len) + es2->es_len > EXT_MAX_BLOCKS) {
 387                pr_warn("ES assertion failed when merging extents. "
 388                        "The sum of lengths of es1 (%d) and es2 (%d) "
 389                        "is bigger than allowed file size (%d)\n",
 390                        es1->es_len, es2->es_len, EXT_MAX_BLOCKS);
 391                WARN_ON(1);
 392                return 0;
 393        }
 394
 395        if (((__u64) es1->es_lblk) + es1->es_len != es2->es_lblk)
 396                return 0;
 397
 398        if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) &&
 399            (ext4_es_pblock(es1) + es1->es_len == ext4_es_pblock(es2)))
 400                return 1;
 401
 402        if (ext4_es_is_hole(es1))
 403                return 1;
 404
 405        /* we need to check delayed extent is without unwritten status */
 406        if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1))
 407                return 1;
 408
 409        return 0;
 410}
 411
 412static struct extent_status *
 413ext4_es_try_to_merge_left(struct inode *inode, struct extent_status *es)
 414{
 415        struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
 416        struct extent_status *es1;
 417        struct rb_node *node;
 418
 419        node = rb_prev(&es->rb_node);
 420        if (!node)
 421                return es;
 422
 423        es1 = rb_entry(node, struct extent_status, rb_node);
 424        if (ext4_es_can_be_merged(es1, es)) {
 425                es1->es_len += es->es_len;
 426                if (ext4_es_is_referenced(es))
 427                        ext4_es_set_referenced(es1);
 428                rb_erase(&es->rb_node, &tree->root);
 429                ext4_es_free_extent(inode, es);
 430                es = es1;
 431        }
 432
 433        return es;
 434}
 435
 436static struct extent_status *
 437ext4_es_try_to_merge_right(struct inode *inode, struct extent_status *es)
 438{
 439        struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
 440        struct extent_status *es1;
 441        struct rb_node *node;
 442
 443        node = rb_next(&es->rb_node);
 444        if (!node)
 445                return es;
 446
 447        es1 = rb_entry(node, struct extent_status, rb_node);
 448        if (ext4_es_can_be_merged(es, es1)) {
 449                es->es_len += es1->es_len;
 450                if (ext4_es_is_referenced(es1))
 451                        ext4_es_set_referenced(es);
 452                rb_erase(node, &tree->root);
 453                ext4_es_free_extent(inode, es1);
 454        }
 455
 456        return es;
 457}
 458
 459#ifdef ES_AGGRESSIVE_TEST
 460#include "ext4_extents.h"       /* Needed when ES_AGGRESSIVE_TEST is defined */
 461
 462static void ext4_es_insert_extent_ext_check(struct inode *inode,
 463                                            struct extent_status *es)
 464{
 465        struct ext4_ext_path *path = NULL;
 466        struct ext4_extent *ex;
 467        ext4_lblk_t ee_block;
 468        ext4_fsblk_t ee_start;
 469        unsigned short ee_len;
 470        int depth, ee_status, es_status;
 471
 472        path = ext4_find_extent(inode, es->es_lblk, NULL, EXT4_EX_NOCACHE);
 473        if (IS_ERR(path))
 474                return;
 475
 476        depth = ext_depth(inode);
 477        ex = path[depth].p_ext;
 478
 479        if (ex) {
 480
 481                ee_block = le32_to_cpu(ex->ee_block);
 482                ee_start = ext4_ext_pblock(ex);
 483                ee_len = ext4_ext_get_actual_len(ex);
 484
 485                ee_status = ext4_ext_is_unwritten(ex) ? 1 : 0;
 486                es_status = ext4_es_is_unwritten(es) ? 1 : 0;
 487
 488                /*
 489                 * Make sure ex and es are not overlap when we try to insert
 490                 * a delayed/hole extent.
 491                 */
 492                if (!ext4_es_is_written(es) && !ext4_es_is_unwritten(es)) {
 493                        if (in_range(es->es_lblk, ee_block, ee_len)) {
 494                                pr_warn("ES insert assertion failed for "
 495                                        "inode: %lu we can find an extent "
 496                                        "at block [%d/%d/%llu/%c], but we "
 497                                        "want to add a delayed/hole extent "
 498                                        "[%d/%d/%llu/%x]\n",
 499                                        inode->i_ino, ee_block, ee_len,
 500                                        ee_start, ee_status ? 'u' : 'w',
 501                                        es->es_lblk, es->es_len,
 502                                        ext4_es_pblock(es), ext4_es_status(es));
 503                        }
 504                        goto out;
 505                }
 506
 507                /*
 508                 * We don't check ee_block == es->es_lblk, etc. because es
 509                 * might be a part of whole extent, vice versa.
 510                 */
 511                if (es->es_lblk < ee_block ||
 512                    ext4_es_pblock(es) != ee_start + es->es_lblk - ee_block) {
 513                        pr_warn("ES insert assertion failed for inode: %lu "
 514                                "ex_status [%d/%d/%llu/%c] != "
 515                                "es_status [%d/%d/%llu/%c]\n", inode->i_ino,
 516                                ee_block, ee_len, ee_start,
 517                                ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
 518                                ext4_es_pblock(es), es_status ? 'u' : 'w');
 519                        goto out;
 520                }
 521
 522                if (ee_status ^ es_status) {
 523                        pr_warn("ES insert assertion failed for inode: %lu "
 524                                "ex_status [%d/%d/%llu/%c] != "
 525                                "es_status [%d/%d/%llu/%c]\n", inode->i_ino,
 526                                ee_block, ee_len, ee_start,
 527                                ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
 528                                ext4_es_pblock(es), es_status ? 'u' : 'w');
 529                }
 530        } else {
 531                /*
 532                 * We can't find an extent on disk.  So we need to make sure
 533                 * that we don't want to add an written/unwritten extent.
 534                 */
 535                if (!ext4_es_is_delayed(es) && !ext4_es_is_hole(es)) {
 536                        pr_warn("ES insert assertion failed for inode: %lu "
 537                                "can't find an extent at block %d but we want "
 538                                "to add a written/unwritten extent "
 539                                "[%d/%d/%llu/%x]\n", inode->i_ino,
 540                                es->es_lblk, es->es_lblk, es->es_len,
 541                                ext4_es_pblock(es), ext4_es_status(es));
 542                }
 543        }
 544out:
 545        ext4_ext_drop_refs(path);
 546        kfree(path);
 547}
 548
 549static void ext4_es_insert_extent_ind_check(struct inode *inode,
 550                                            struct extent_status *es)
 551{
 552        struct ext4_map_blocks map;
 553        int retval;
 554
 555        /*
 556         * Here we call ext4_ind_map_blocks to lookup a block mapping because
 557         * 'Indirect' structure is defined in indirect.c.  So we couldn't
 558         * access direct/indirect tree from outside.  It is too dirty to define
 559         * this function in indirect.c file.
 560         */
 561
 562        map.m_lblk = es->es_lblk;
 563        map.m_len = es->es_len;
 564
 565        retval = ext4_ind_map_blocks(NULL, inode, &map, 0);
 566        if (retval > 0) {
 567                if (ext4_es_is_delayed(es) || ext4_es_is_hole(es)) {
 568                        /*
 569                         * We want to add a delayed/hole extent but this
 570                         * block has been allocated.
 571                         */
 572                        pr_warn("ES insert assertion failed for inode: %lu "
 573                                "We can find blocks but we want to add a "
 574                                "delayed/hole extent [%d/%d/%llu/%x]\n",
 575                                inode->i_ino, es->es_lblk, es->es_len,
 576                                ext4_es_pblock(es), ext4_es_status(es));
 577                        return;
 578                } else if (ext4_es_is_written(es)) {
 579                        if (retval != es->es_len) {
 580                                pr_warn("ES insert assertion failed for "
 581                                        "inode: %lu retval %d != es_len %d\n",
 582                                        inode->i_ino, retval, es->es_len);
 583                                return;
 584                        }
 585                        if (map.m_pblk != ext4_es_pblock(es)) {
 586                                pr_warn("ES insert assertion failed for "
 587                                        "inode: %lu m_pblk %llu != "
 588                                        "es_pblk %llu\n",
 589                                        inode->i_ino, map.m_pblk,
 590                                        ext4_es_pblock(es));
 591                                return;
 592                        }
 593                } else {
 594                        /*
 595                         * We don't need to check unwritten extent because
 596                         * indirect-based file doesn't have it.
 597                         */
 598                        BUG_ON(1);
 599                }
 600        } else if (retval == 0) {
 601                if (ext4_es_is_written(es)) {
 602                        pr_warn("ES insert assertion failed for inode: %lu "
 603                                "We can't find the block but we want to add "
 604                                "a written extent [%d/%d/%llu/%x]\n",
 605                                inode->i_ino, es->es_lblk, es->es_len,
 606                                ext4_es_pblock(es), ext4_es_status(es));
 607                        return;
 608                }
 609        }
 610}
 611
 612static inline void ext4_es_insert_extent_check(struct inode *inode,
 613                                               struct extent_status *es)
 614{
 615        /*
 616         * We don't need to worry about the race condition because
 617         * caller takes i_data_sem locking.
 618         */
 619        BUG_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
 620        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
 621                ext4_es_insert_extent_ext_check(inode, es);
 622        else
 623                ext4_es_insert_extent_ind_check(inode, es);
 624}
 625#else
 626static inline void ext4_es_insert_extent_check(struct inode *inode,
 627                                               struct extent_status *es)
 628{
 629}
 630#endif
 631
 632static int __es_insert_extent(struct inode *inode, struct extent_status *newes)
 633{
 634        struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
 635        struct rb_node **p = &tree->root.rb_node;
 636        struct rb_node *parent = NULL;
 637        struct extent_status *es;
 638
 639        while (*p) {
 640                parent = *p;
 641                es = rb_entry(parent, struct extent_status, rb_node);
 642
 643                if (newes->es_lblk < es->es_lblk) {
 644                        if (ext4_es_can_be_merged(newes, es)) {
 645                                /*
 646                                 * Here we can modify es_lblk directly
 647                                 * because it isn't overlapped.
 648                                 */
 649                                es->es_lblk = newes->es_lblk;
 650                                es->es_len += newes->es_len;
 651                                if (ext4_es_is_written(es) ||
 652                                    ext4_es_is_unwritten(es))
 653                                        ext4_es_store_pblock(es,
 654                                                             newes->es_pblk);
 655                                es = ext4_es_try_to_merge_left(inode, es);
 656                                goto out;
 657                        }
 658                        p = &(*p)->rb_left;
 659                } else if (newes->es_lblk > ext4_es_end(es)) {
 660                        if (ext4_es_can_be_merged(es, newes)) {
 661                                es->es_len += newes->es_len;
 662                                es = ext4_es_try_to_merge_right(inode, es);
 663                                goto out;
 664                        }
 665                        p = &(*p)->rb_right;
 666                } else {
 667                        BUG_ON(1);
 668                        return -EINVAL;
 669                }
 670        }
 671
 672        es = ext4_es_alloc_extent(inode, newes->es_lblk, newes->es_len,
 673                                  newes->es_pblk);
 674        if (!es)
 675                return -ENOMEM;
 676        rb_link_node(&es->rb_node, parent, p);
 677        rb_insert_color(&es->rb_node, &tree->root);
 678
 679out:
 680        tree->cache_es = es;
 681        return 0;
 682}
 683
 684/*
 685 * ext4_es_insert_extent() adds information to an inode's extent
 686 * status tree.
 687 *
 688 * Return 0 on success, error code on failure.
 689 */
 690int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 691                          ext4_lblk_t len, ext4_fsblk_t pblk,
 692                          unsigned int status)
 693{
 694        struct extent_status newes;
 695        ext4_lblk_t end = lblk + len - 1;
 696        int err = 0;
 697
 698        es_debug("add [%u/%u) %llu %x to extent status tree of inode %lu\n",
 699                 lblk, len, pblk, status, inode->i_ino);
 700
 701        if (!len)
 702                return 0;
 703
 704        BUG_ON(end < lblk);
 705
 706        if ((status & EXTENT_STATUS_DELAYED) &&
 707            (status & EXTENT_STATUS_WRITTEN)) {
 708                ext4_warning(inode->i_sb, "Inserting extent [%u/%u] as "
 709                                " delayed and written which can potentially "
 710                                " cause data loss.", lblk, len);
 711                WARN_ON(1);
 712        }
 713
 714        newes.es_lblk = lblk;
 715        newes.es_len = len;
 716        ext4_es_store_pblock_status(&newes, pblk, status);
 717        trace_ext4_es_insert_extent(inode, &newes);
 718
 719        ext4_es_insert_extent_check(inode, &newes);
 720
 721        write_lock(&EXT4_I(inode)->i_es_lock);
 722        err = __es_remove_extent(inode, lblk, end);
 723        if (err != 0)
 724                goto error;
 725retry:
 726        err = __es_insert_extent(inode, &newes);
 727        if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
 728                                          128, EXT4_I(inode)))
 729                goto retry;
 730        if (err == -ENOMEM && !ext4_es_is_delayed(&newes))
 731                err = 0;
 732
 733error:
 734        write_unlock(&EXT4_I(inode)->i_es_lock);
 735
 736        ext4_es_print_tree(inode);
 737
 738        return err;
 739}
 740
 741/*
 742 * ext4_es_cache_extent() inserts information into the extent status
 743 * tree if and only if there isn't information about the range in
 744 * question already.
 745 */
 746void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk,
 747                          ext4_lblk_t len, ext4_fsblk_t pblk,
 748                          unsigned int status)
 749{
 750        struct extent_status *es;
 751        struct extent_status newes;
 752        ext4_lblk_t end = lblk + len - 1;
 753
 754        newes.es_lblk = lblk;
 755        newes.es_len = len;
 756        ext4_es_store_pblock_status(&newes, pblk, status);
 757        trace_ext4_es_cache_extent(inode, &newes);
 758
 759        if (!len)
 760                return;
 761
 762        BUG_ON(end < lblk);
 763
 764        write_lock(&EXT4_I(inode)->i_es_lock);
 765
 766        es = __es_tree_search(&EXT4_I(inode)->i_es_tree.root, lblk);
 767        if (!es || es->es_lblk > end)
 768                __es_insert_extent(inode, &newes);
 769        write_unlock(&EXT4_I(inode)->i_es_lock);
 770}
 771
 772/*
 773 * ext4_es_lookup_extent() looks up an extent in extent status tree.
 774 *
 775 * ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
 776 *
 777 * Return: 1 on found, 0 on not
 778 */
 779int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
 780                          struct extent_status *es)
 781{
 782        struct ext4_es_tree *tree;
 783        struct ext4_es_stats *stats;
 784        struct extent_status *es1 = NULL;
 785        struct rb_node *node;
 786        int found = 0;
 787
 788        trace_ext4_es_lookup_extent_enter(inode, lblk);
 789        es_debug("lookup extent in block %u\n", lblk);
 790
 791        tree = &EXT4_I(inode)->i_es_tree;
 792        read_lock(&EXT4_I(inode)->i_es_lock);
 793
 794        /* find extent in cache firstly */
 795        es->es_lblk = es->es_len = es->es_pblk = 0;
 796        if (tree->cache_es) {
 797                es1 = tree->cache_es;
 798                if (in_range(lblk, es1->es_lblk, es1->es_len)) {
 799                        es_debug("%u cached by [%u/%u)\n",
 800                                 lblk, es1->es_lblk, es1->es_len);
 801                        found = 1;
 802                        goto out;
 803                }
 804        }
 805
 806        node = tree->root.rb_node;
 807        while (node) {
 808                es1 = rb_entry(node, struct extent_status, rb_node);
 809                if (lblk < es1->es_lblk)
 810                        node = node->rb_left;
 811                else if (lblk > ext4_es_end(es1))
 812                        node = node->rb_right;
 813                else {
 814                        found = 1;
 815                        break;
 816                }
 817        }
 818
 819out:
 820        stats = &EXT4_SB(inode->i_sb)->s_es_stats;
 821        if (found) {
 822                BUG_ON(!es1);
 823                es->es_lblk = es1->es_lblk;
 824                es->es_len = es1->es_len;
 825                es->es_pblk = es1->es_pblk;
 826                if (!ext4_es_is_referenced(es1))
 827                        ext4_es_set_referenced(es1);
 828                stats->es_stats_cache_hits++;
 829        } else {
 830                stats->es_stats_cache_misses++;
 831        }
 832
 833        read_unlock(&EXT4_I(inode)->i_es_lock);
 834
 835        trace_ext4_es_lookup_extent_exit(inode, es, found);
 836        return found;
 837}
 838
 839static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
 840                              ext4_lblk_t end)
 841{
 842        struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
 843        struct rb_node *node;
 844        struct extent_status *es;
 845        struct extent_status orig_es;
 846        ext4_lblk_t len1, len2;
 847        ext4_fsblk_t block;
 848        int err;
 849
 850retry:
 851        err = 0;
 852        es = __es_tree_search(&tree->root, lblk);
 853        if (!es)
 854                goto out;
 855        if (es->es_lblk > end)
 856                goto out;
 857
 858        /* Simply invalidate cache_es. */
 859        tree->cache_es = NULL;
 860
 861        orig_es.es_lblk = es->es_lblk;
 862        orig_es.es_len = es->es_len;
 863        orig_es.es_pblk = es->es_pblk;
 864
 865        len1 = lblk > es->es_lblk ? lblk - es->es_lblk : 0;
 866        len2 = ext4_es_end(es) > end ? ext4_es_end(es) - end : 0;
 867        if (len1 > 0)
 868                es->es_len = len1;
 869        if (len2 > 0) {
 870                if (len1 > 0) {
 871                        struct extent_status newes;
 872
 873                        newes.es_lblk = end + 1;
 874                        newes.es_len = len2;
 875                        block = 0x7FDEADBEEFULL;
 876                        if (ext4_es_is_written(&orig_es) ||
 877                            ext4_es_is_unwritten(&orig_es))
 878                                block = ext4_es_pblock(&orig_es) +
 879                                        orig_es.es_len - len2;
 880                        ext4_es_store_pblock_status(&newes, block,
 881                                                    ext4_es_status(&orig_es));
 882                        err = __es_insert_extent(inode, &newes);
 883                        if (err) {
 884                                es->es_lblk = orig_es.es_lblk;
 885                                es->es_len = orig_es.es_len;
 886                                if ((err == -ENOMEM) &&
 887                                    __es_shrink(EXT4_SB(inode->i_sb),
 888                                                        128, EXT4_I(inode)))
 889                                        goto retry;
 890                                goto out;
 891                        }
 892                } else {
 893                        es->es_lblk = end + 1;
 894                        es->es_len = len2;
 895                        if (ext4_es_is_written(es) ||
 896                            ext4_es_is_unwritten(es)) {
 897                                block = orig_es.es_pblk + orig_es.es_len - len2;
 898                                ext4_es_store_pblock(es, block);
 899                        }
 900                }
 901                goto out;
 902        }
 903
 904        if (len1 > 0) {
 905                node = rb_next(&es->rb_node);
 906                if (node)
 907                        es = rb_entry(node, struct extent_status, rb_node);
 908                else
 909                        es = NULL;
 910        }
 911
 912        while (es && ext4_es_end(es) <= end) {
 913                node = rb_next(&es->rb_node);
 914                rb_erase(&es->rb_node, &tree->root);
 915                ext4_es_free_extent(inode, es);
 916                if (!node) {
 917                        es = NULL;
 918                        break;
 919                }
 920                es = rb_entry(node, struct extent_status, rb_node);
 921        }
 922
 923        if (es && es->es_lblk < end + 1) {
 924                ext4_lblk_t orig_len = es->es_len;
 925
 926                len1 = ext4_es_end(es) - end;
 927                es->es_lblk = end + 1;
 928                es->es_len = len1;
 929                if (ext4_es_is_written(es) || ext4_es_is_unwritten(es)) {
 930                        block = es->es_pblk + orig_len - len1;
 931                        ext4_es_store_pblock(es, block);
 932                }
 933        }
 934
 935out:
 936        return err;
 937}
 938
 939/*
 940 * ext4_es_remove_extent() removes a space from a extent status tree.
 941 *
 942 * Return 0 on success, error code on failure.
 943 */
 944int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
 945                          ext4_lblk_t len)
 946{
 947        ext4_lblk_t end;
 948        int err = 0;
 949
 950        trace_ext4_es_remove_extent(inode, lblk, len);
 951        es_debug("remove [%u/%u) from extent status tree of inode %lu\n",
 952                 lblk, len, inode->i_ino);
 953
 954        if (!len)
 955                return err;
 956
 957        end = lblk + len - 1;
 958        BUG_ON(end < lblk);
 959
 960        /*
 961         * ext4_clear_inode() depends on us taking i_es_lock unconditionally
 962         * so that we are sure __es_shrink() is done with the inode before it
 963         * is reclaimed.
 964         */
 965        write_lock(&EXT4_I(inode)->i_es_lock);
 966        err = __es_remove_extent(inode, lblk, end);
 967        write_unlock(&EXT4_I(inode)->i_es_lock);
 968        ext4_es_print_tree(inode);
 969        return err;
 970}
 971
 972static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
 973                       struct ext4_inode_info *locked_ei)
 974{
 975        struct ext4_inode_info *ei;
 976        struct ext4_es_stats *es_stats;
 977        ktime_t start_time;
 978        u64 scan_time;
 979        int nr_to_walk;
 980        int nr_shrunk = 0;
 981        int retried = 0, nr_skipped = 0;
 982
 983        es_stats = &sbi->s_es_stats;
 984        start_time = ktime_get();
 985
 986retry:
 987        spin_lock(&sbi->s_es_lock);
 988        nr_to_walk = sbi->s_es_nr_inode;
 989        while (nr_to_walk-- > 0) {
 990                if (list_empty(&sbi->s_es_list)) {
 991                        spin_unlock(&sbi->s_es_lock);
 992                        goto out;
 993                }
 994                ei = list_first_entry(&sbi->s_es_list, struct ext4_inode_info,
 995                                      i_es_list);
 996                /* Move the inode to the tail */
 997                list_move_tail(&ei->i_es_list, &sbi->s_es_list);
 998
 999                /*
1000                 * Normally we try hard to avoid shrinking precached inodes,
1001                 * but we will as a last resort.
1002                 */
1003                if (!retried && ext4_test_inode_state(&ei->vfs_inode,
1004                                                EXT4_STATE_EXT_PRECACHED)) {
1005                        nr_skipped++;
1006                        continue;
1007                }
1008
1009                if (ei == locked_ei || !write_trylock(&ei->i_es_lock)) {
1010                        nr_skipped++;
1011                        continue;
1012                }
1013                /*
1014                 * Now we hold i_es_lock which protects us from inode reclaim
1015                 * freeing inode under us
1016                 */
1017                spin_unlock(&sbi->s_es_lock);
1018
1019                nr_shrunk += es_reclaim_extents(ei, &nr_to_scan);
1020                write_unlock(&ei->i_es_lock);
1021
1022                if (nr_to_scan <= 0)
1023                        goto out;
1024                spin_lock(&sbi->s_es_lock);
1025        }
1026        spin_unlock(&sbi->s_es_lock);
1027
1028        /*
1029         * If we skipped any inodes, and we weren't able to make any
1030         * forward progress, try again to scan precached inodes.
1031         */
1032        if ((nr_shrunk == 0) && nr_skipped && !retried) {
1033                retried++;
1034                goto retry;
1035        }
1036
1037        if (locked_ei && nr_shrunk == 0)
1038                nr_shrunk = es_reclaim_extents(locked_ei, &nr_to_scan);
1039
1040out:
1041        scan_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1042        if (likely(es_stats->es_stats_scan_time))
1043                es_stats->es_stats_scan_time = (scan_time +
1044                                es_stats->es_stats_scan_time*3) / 4;
1045        else
1046                es_stats->es_stats_scan_time = scan_time;
1047        if (scan_time > es_stats->es_stats_max_scan_time)
1048                es_stats->es_stats_max_scan_time = scan_time;
1049        if (likely(es_stats->es_stats_shrunk))
1050                es_stats->es_stats_shrunk = (nr_shrunk +
1051                                es_stats->es_stats_shrunk*3) / 4;
1052        else
1053                es_stats->es_stats_shrunk = nr_shrunk;
1054
1055        trace_ext4_es_shrink(sbi->s_sb, nr_shrunk, scan_time,
1056                             nr_skipped, retried);
1057        return nr_shrunk;
1058}
1059
1060static unsigned long ext4_es_count(struct shrinker *shrink,
1061                                   struct shrink_control *sc)
1062{
1063        unsigned long nr;
1064        struct ext4_sb_info *sbi;
1065
1066        sbi = container_of(shrink, struct ext4_sb_info, s_es_shrinker);
1067        nr = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
1068        trace_ext4_es_shrink_count(sbi->s_sb, sc->nr_to_scan, nr);
1069        return nr;
1070}
1071
1072static unsigned long ext4_es_scan(struct shrinker *shrink,
1073                                  struct shrink_control *sc)
1074{
1075        struct ext4_sb_info *sbi = container_of(shrink,
1076                                        struct ext4_sb_info, s_es_shrinker);
1077        int nr_to_scan = sc->nr_to_scan;
1078        int ret, nr_shrunk;
1079
1080        ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
1081        trace_ext4_es_shrink_scan_enter(sbi->s_sb, nr_to_scan, ret);
1082
1083        if (!nr_to_scan)
1084                return ret;
1085
1086        nr_shrunk = __es_shrink(sbi, nr_to_scan, NULL);
1087
1088        trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);
1089        return nr_shrunk;
1090}
1091
1092int ext4_seq_es_shrinker_info_show(struct seq_file *seq, void *v)
1093{
1094        struct ext4_sb_info *sbi = EXT4_SB((struct super_block *) seq->private);
1095        struct ext4_es_stats *es_stats = &sbi->s_es_stats;
1096        struct ext4_inode_info *ei, *max = NULL;
1097        unsigned int inode_cnt = 0;
1098
1099        if (v != SEQ_START_TOKEN)
1100                return 0;
1101
1102        /* here we just find an inode that has the max nr. of objects */
1103        spin_lock(&sbi->s_es_lock);
1104        list_for_each_entry(ei, &sbi->s_es_list, i_es_list) {
1105                inode_cnt++;
1106                if (max && max->i_es_all_nr < ei->i_es_all_nr)
1107                        max = ei;
1108                else if (!max)
1109                        max = ei;
1110        }
1111        spin_unlock(&sbi->s_es_lock);
1112
1113        seq_printf(seq, "stats:\n  %lld objects\n  %lld reclaimable objects\n",
1114                   percpu_counter_sum_positive(&es_stats->es_stats_all_cnt),
1115                   percpu_counter_sum_positive(&es_stats->es_stats_shk_cnt));
1116        seq_printf(seq, "  %lu/%lu cache hits/misses\n",
1117                   es_stats->es_stats_cache_hits,
1118                   es_stats->es_stats_cache_misses);
1119        if (inode_cnt)
1120                seq_printf(seq, "  %d inodes on list\n", inode_cnt);
1121
1122        seq_printf(seq, "average:\n  %llu us scan time\n",
1123            div_u64(es_stats->es_stats_scan_time, 1000));
1124        seq_printf(seq, "  %lu shrunk objects\n", es_stats->es_stats_shrunk);
1125        if (inode_cnt)
1126                seq_printf(seq,
1127                    "maximum:\n  %lu inode (%u objects, %u reclaimable)\n"
1128                    "  %llu us max scan time\n",
1129                    max->vfs_inode.i_ino, max->i_es_all_nr, max->i_es_shk_nr,
1130                    div_u64(es_stats->es_stats_max_scan_time, 1000));
1131
1132        return 0;
1133}
1134
1135int ext4_es_register_shrinker(struct ext4_sb_info *sbi)
1136{
1137        int err;
1138
1139        /* Make sure we have enough bits for physical block number */
1140        BUILD_BUG_ON(ES_SHIFT < 48);
1141        INIT_LIST_HEAD(&sbi->s_es_list);
1142        sbi->s_es_nr_inode = 0;
1143        spin_lock_init(&sbi->s_es_lock);
1144        sbi->s_es_stats.es_stats_shrunk = 0;
1145        sbi->s_es_stats.es_stats_cache_hits = 0;
1146        sbi->s_es_stats.es_stats_cache_misses = 0;
1147        sbi->s_es_stats.es_stats_scan_time = 0;
1148        sbi->s_es_stats.es_stats_max_scan_time = 0;
1149        err = percpu_counter_init(&sbi->s_es_stats.es_stats_all_cnt, 0, GFP_KERNEL);
1150        if (err)
1151                return err;
1152        err = percpu_counter_init(&sbi->s_es_stats.es_stats_shk_cnt, 0, GFP_KERNEL);
1153        if (err)
1154                goto err1;
1155
1156        sbi->s_es_shrinker.scan_objects = ext4_es_scan;
1157        sbi->s_es_shrinker.count_objects = ext4_es_count;
1158        sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
1159        err = register_shrinker(&sbi->s_es_shrinker);
1160        if (err)
1161                goto err2;
1162
1163        return 0;
1164
1165err2:
1166        percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
1167err1:
1168        percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
1169        return err;
1170}
1171
1172void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
1173{
1174        percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
1175        percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
1176        unregister_shrinker(&sbi->s_es_shrinker);
1177}
1178
1179/*
1180 * Shrink extents in given inode from ei->i_es_shrink_lblk till end. Scan at
1181 * most *nr_to_scan extents, update *nr_to_scan accordingly.
1182 *
1183 * Return 0 if we hit end of tree / interval, 1 if we exhausted nr_to_scan.
1184 * Increment *nr_shrunk by the number of reclaimed extents. Also update
1185 * ei->i_es_shrink_lblk to where we should continue scanning.
1186 */
1187static int es_do_reclaim_extents(struct ext4_inode_info *ei, ext4_lblk_t end,
1188                                 int *nr_to_scan, int *nr_shrunk)
1189{
1190        struct inode *inode = &ei->vfs_inode;
1191        struct ext4_es_tree *tree = &ei->i_es_tree;
1192        struct extent_status *es;
1193        struct rb_node *node;
1194
1195        es = __es_tree_search(&tree->root, ei->i_es_shrink_lblk);
1196        if (!es)
1197                goto out_wrap;
1198        node = &es->rb_node;
1199        while (*nr_to_scan > 0) {
1200                if (es->es_lblk > end) {
1201                        ei->i_es_shrink_lblk = end + 1;
1202                        return 0;
1203                }
1204
1205                (*nr_to_scan)--;
1206                node = rb_next(&es->rb_node);
1207                /*
1208                 * We can't reclaim delayed extent from status tree because
1209                 * fiemap, bigallic, and seek_data/hole need to use it.
1210                 */
1211                if (ext4_es_is_delayed(es))
1212                        goto next;
1213                if (ext4_es_is_referenced(es)) {
1214                        ext4_es_clear_referenced(es);
1215                        goto next;
1216                }
1217
1218                rb_erase(&es->rb_node, &tree->root);
1219                ext4_es_free_extent(inode, es);
1220                (*nr_shrunk)++;
1221next:
1222                if (!node)
1223                        goto out_wrap;
1224                es = rb_entry(node, struct extent_status, rb_node);
1225        }
1226        ei->i_es_shrink_lblk = es->es_lblk;
1227        return 1;
1228out_wrap:
1229        ei->i_es_shrink_lblk = 0;
1230        return 0;
1231}
1232
1233static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan)
1234{
1235        struct inode *inode = &ei->vfs_inode;
1236        int nr_shrunk = 0;
1237        ext4_lblk_t start = ei->i_es_shrink_lblk;
1238        static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
1239                                      DEFAULT_RATELIMIT_BURST);
1240
1241        if (ei->i_es_shk_nr == 0)
1242                return 0;
1243
1244        if (ext4_test_inode_state(inode, EXT4_STATE_EXT_PRECACHED) &&
1245            __ratelimit(&_rs))
1246                ext4_warning(inode->i_sb, "forced shrink of precached extents");
1247
1248        if (!es_do_reclaim_extents(ei, EXT_MAX_BLOCKS, nr_to_scan, &nr_shrunk) &&
1249            start != 0)
1250                es_do_reclaim_extents(ei, start - 1, nr_to_scan, &nr_shrunk);
1251
1252        ei->i_es_tree.cache_es = NULL;
1253        return nr_shrunk;
1254}
1255