linux/fs/ocfs2/reservations.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * reservations.c
   4 *
   5 * Allocation reservations implementation
   6 *
   7 * Some code borrowed from fs/ext3/balloc.c and is:
   8 *
   9 * Copyright (C) 1992, 1993, 1994, 1995
  10 * Remy Card (card@masi.ibp.fr)
  11 * Laboratoire MASI - Institut Blaise Pascal
  12 * Universite Pierre et Marie Curie (Paris VI)
  13 *
  14 * The rest is copyright (C) 2010 Novell.  All rights reserved.
  15 */
  16
  17#include <linux/fs.h>
  18#include <linux/types.h>
  19#include <linux/highmem.h>
  20#include <linux/bitops.h>
  21#include <linux/list.h>
  22
  23#include <cluster/masklog.h>
  24
  25#include "ocfs2.h"
  26#include "ocfs2_trace.h"
  27
  28#ifdef CONFIG_OCFS2_DEBUG_FS
  29#define OCFS2_CHECK_RESERVATIONS
  30#endif
  31
  32static DEFINE_SPINLOCK(resv_lock);
  33
  34int ocfs2_dir_resv_allowed(struct ocfs2_super *osb)
  35{
  36        return (osb->osb_resv_level && osb->osb_dir_resv_level);
  37}
  38
  39static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap,
  40                                           struct ocfs2_alloc_reservation *resv)
  41{
  42        struct ocfs2_super *osb = resmap->m_osb;
  43        unsigned int bits;
  44
  45        if (!(resv->r_flags & OCFS2_RESV_FLAG_DIR)) {
  46                /* 8, 16, 32, 64, 128, 256, 512, 1024 */
  47                bits = 4 << osb->osb_resv_level;
  48        } else {
  49                bits = 4 << osb->osb_dir_resv_level;
  50        }
  51        return bits;
  52}
  53
  54static inline unsigned int ocfs2_resv_end(struct ocfs2_alloc_reservation *resv)
  55{
  56        if (resv->r_len)
  57                return resv->r_start + resv->r_len - 1;
  58        return resv->r_start;
  59}
  60
  61static inline int ocfs2_resv_empty(struct ocfs2_alloc_reservation *resv)
  62{
  63        return !!(resv->r_len == 0);
  64}
  65
  66static inline int ocfs2_resmap_disabled(struct ocfs2_reservation_map *resmap)
  67{
  68        if (resmap->m_osb->osb_resv_level == 0)
  69                return 1;
  70        return 0;
  71}
  72
  73static void ocfs2_dump_resv(struct ocfs2_reservation_map *resmap)
  74{
  75        struct ocfs2_super *osb = resmap->m_osb;
  76        struct rb_node *node;
  77        struct ocfs2_alloc_reservation *resv;
  78        int i = 0;
  79
  80        mlog(ML_NOTICE, "Dumping resmap for device %s. Bitmap length: %u\n",
  81             osb->dev_str, resmap->m_bitmap_len);
  82
  83        node = rb_first(&resmap->m_reservations);
  84        while (node) {
  85                resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
  86
  87                mlog(ML_NOTICE, "start: %u\tend: %u\tlen: %u\tlast_start: %u"
  88                     "\tlast_len: %u\n", resv->r_start,
  89                     ocfs2_resv_end(resv), resv->r_len, resv->r_last_start,
  90                     resv->r_last_len);
  91
  92                node = rb_next(node);
  93                i++;
  94        }
  95
  96        mlog(ML_NOTICE, "%d reservations found. LRU follows\n", i);
  97
  98        i = 0;
  99        list_for_each_entry(resv, &resmap->m_lru, r_lru) {
 100                mlog(ML_NOTICE, "LRU(%d) start: %u\tend: %u\tlen: %u\t"
 101                     "last_start: %u\tlast_len: %u\n", i, resv->r_start,
 102                     ocfs2_resv_end(resv), resv->r_len, resv->r_last_start,
 103                     resv->r_last_len);
 104
 105                i++;
 106        }
 107}
 108
 109#ifdef OCFS2_CHECK_RESERVATIONS
 110static int ocfs2_validate_resmap_bits(struct ocfs2_reservation_map *resmap,
 111                                      int i,
 112                                      struct ocfs2_alloc_reservation *resv)
 113{
 114        char *disk_bitmap = resmap->m_disk_bitmap;
 115        unsigned int start = resv->r_start;
 116        unsigned int end = ocfs2_resv_end(resv);
 117
 118        while (start <= end) {
 119                if (ocfs2_test_bit(start, disk_bitmap)) {
 120                        mlog(ML_ERROR,
 121                             "reservation %d covers an allocated area "
 122                             "starting at bit %u!\n", i, start);
 123                        return 1;
 124                }
 125
 126                start++;
 127        }
 128        return 0;
 129}
 130
 131static void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap)
 132{
 133        unsigned int off = 0;
 134        int i = 0;
 135        struct rb_node *node;
 136        struct ocfs2_alloc_reservation *resv;
 137
 138        node = rb_first(&resmap->m_reservations);
 139        while (node) {
 140                resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
 141
 142                if (i > 0 && resv->r_start <= off) {
 143                        mlog(ML_ERROR, "reservation %d has bad start off!\n",
 144                             i);
 145                        goto bad;
 146                }
 147
 148                if (resv->r_len == 0) {
 149                        mlog(ML_ERROR, "reservation %d has no length!\n",
 150                             i);
 151                        goto bad;
 152                }
 153
 154                if (resv->r_start > ocfs2_resv_end(resv)) {
 155                        mlog(ML_ERROR, "reservation %d has invalid range!\n",
 156                             i);
 157                        goto bad;
 158                }
 159
 160                if (ocfs2_resv_end(resv) >= resmap->m_bitmap_len) {
 161                        mlog(ML_ERROR, "reservation %d extends past bitmap!\n",
 162                             i);
 163                        goto bad;
 164                }
 165
 166                if (ocfs2_validate_resmap_bits(resmap, i, resv))
 167                        goto bad;
 168
 169                off = ocfs2_resv_end(resv);
 170                node = rb_next(node);
 171
 172                i++;
 173        }
 174        return;
 175
 176bad:
 177        ocfs2_dump_resv(resmap);
 178        BUG();
 179}
 180#else
 181static inline void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap)
 182{
 183
 184}
 185#endif
 186
 187void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv)
 188{
 189        memset(resv, 0, sizeof(*resv));
 190        INIT_LIST_HEAD(&resv->r_lru);
 191}
 192
 193void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
 194                         unsigned int flags)
 195{
 196        BUG_ON(flags & ~OCFS2_RESV_TYPES);
 197
 198        resv->r_flags |= flags;
 199}
 200
 201int ocfs2_resmap_init(struct ocfs2_super *osb,
 202                      struct ocfs2_reservation_map *resmap)
 203{
 204        memset(resmap, 0, sizeof(*resmap));
 205
 206        resmap->m_osb = osb;
 207        resmap->m_reservations = RB_ROOT;
 208        /* m_bitmap_len is initialized to zero by the above memset. */
 209        INIT_LIST_HEAD(&resmap->m_lru);
 210
 211        return 0;
 212}
 213
 214static void ocfs2_resv_mark_lru(struct ocfs2_reservation_map *resmap,
 215                                struct ocfs2_alloc_reservation *resv)
 216{
 217        assert_spin_locked(&resv_lock);
 218
 219        if (!list_empty(&resv->r_lru))
 220                list_del_init(&resv->r_lru);
 221
 222        list_add_tail(&resv->r_lru, &resmap->m_lru);
 223}
 224
 225static void __ocfs2_resv_trunc(struct ocfs2_alloc_reservation *resv)
 226{
 227        resv->r_len = 0;
 228        resv->r_start = 0;
 229}
 230
 231static void ocfs2_resv_remove(struct ocfs2_reservation_map *resmap,
 232                              struct ocfs2_alloc_reservation *resv)
 233{
 234        if (resv->r_flags & OCFS2_RESV_FLAG_INUSE) {
 235                list_del_init(&resv->r_lru);
 236                rb_erase(&resv->r_node, &resmap->m_reservations);
 237                resv->r_flags &= ~OCFS2_RESV_FLAG_INUSE;
 238        }
 239}
 240
 241static void __ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
 242                                 struct ocfs2_alloc_reservation *resv)
 243{
 244        assert_spin_locked(&resv_lock);
 245
 246        __ocfs2_resv_trunc(resv);
 247        /*
 248         * last_len and last_start no longer make sense if
 249         * we're changing the range of our allocations.
 250         */
 251        resv->r_last_len = resv->r_last_start = 0;
 252
 253        ocfs2_resv_remove(resmap, resv);
 254}
 255
 256/* does nothing if 'resv' is null */
 257void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
 258                        struct ocfs2_alloc_reservation *resv)
 259{
 260        if (resv) {
 261                spin_lock(&resv_lock);
 262                __ocfs2_resv_discard(resmap, resv);
 263                spin_unlock(&resv_lock);
 264        }
 265}
 266
 267static void ocfs2_resmap_clear_all_resv(struct ocfs2_reservation_map *resmap)
 268{
 269        struct rb_node *node;
 270        struct ocfs2_alloc_reservation *resv;
 271
 272        assert_spin_locked(&resv_lock);
 273
 274        while ((node = rb_last(&resmap->m_reservations)) != NULL) {
 275                resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
 276
 277                __ocfs2_resv_discard(resmap, resv);
 278        }
 279}
 280
 281void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
 282                          unsigned int clen, char *disk_bitmap)
 283{
 284        if (ocfs2_resmap_disabled(resmap))
 285                return;
 286
 287        spin_lock(&resv_lock);
 288
 289        ocfs2_resmap_clear_all_resv(resmap);
 290        resmap->m_bitmap_len = clen;
 291        resmap->m_disk_bitmap = disk_bitmap;
 292
 293        spin_unlock(&resv_lock);
 294}
 295
 296void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap)
 297{
 298        /* Does nothing for now. Keep this around for API symmetry */
 299}
 300
 301static void ocfs2_resv_insert(struct ocfs2_reservation_map *resmap,
 302                              struct ocfs2_alloc_reservation *new)
 303{
 304        struct rb_root *root = &resmap->m_reservations;
 305        struct rb_node *parent = NULL;
 306        struct rb_node **p = &root->rb_node;
 307        struct ocfs2_alloc_reservation *tmp;
 308
 309        assert_spin_locked(&resv_lock);
 310
 311        trace_ocfs2_resv_insert(new->r_start, new->r_len);
 312
 313        while (*p) {
 314                parent = *p;
 315
 316                tmp = rb_entry(parent, struct ocfs2_alloc_reservation, r_node);
 317
 318                if (new->r_start < tmp->r_start) {
 319                        p = &(*p)->rb_left;
 320
 321                        /*
 322                         * This is a good place to check for
 323                         * overlapping reservations.
 324                         */
 325                        BUG_ON(ocfs2_resv_end(new) >= tmp->r_start);
 326                } else if (new->r_start > ocfs2_resv_end(tmp)) {
 327                        p = &(*p)->rb_right;
 328                } else {
 329                        /* This should never happen! */
 330                        mlog(ML_ERROR, "Duplicate reservation window!\n");
 331                        BUG();
 332                }
 333        }
 334
 335        rb_link_node(&new->r_node, parent, p);
 336        rb_insert_color(&new->r_node, root);
 337        new->r_flags |= OCFS2_RESV_FLAG_INUSE;
 338
 339        ocfs2_resv_mark_lru(resmap, new);
 340
 341        ocfs2_check_resmap(resmap);
 342}
 343
 344/**
 345 * ocfs2_find_resv_lhs() - find the window which contains goal
 346 * @resmap: reservation map to search
 347 * @goal: which bit to search for
 348 *
 349 * If a window containing that goal is not found, we return the window
 350 * which comes before goal. Returns NULL on empty rbtree or no window
 351 * before goal.
 352 */
 353static struct ocfs2_alloc_reservation *
 354ocfs2_find_resv_lhs(struct ocfs2_reservation_map *resmap, unsigned int goal)
 355{
 356        struct ocfs2_alloc_reservation *resv = NULL;
 357        struct ocfs2_alloc_reservation *prev_resv = NULL;
 358        struct rb_node *node = resmap->m_reservations.rb_node;
 359
 360        assert_spin_locked(&resv_lock);
 361
 362        if (!node)
 363                return NULL;
 364
 365        node = rb_first(&resmap->m_reservations);
 366        while (node) {
 367                resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
 368
 369                if (resv->r_start <= goal && ocfs2_resv_end(resv) >= goal)
 370                        break;
 371
 372                /* Check if we overshot the reservation just before goal? */
 373                if (resv->r_start > goal) {
 374                        resv = prev_resv;
 375                        break;
 376                }
 377
 378                prev_resv = resv;
 379                node = rb_next(node);
 380        }
 381
 382        return resv;
 383}
 384
 385/*
 386 * We are given a range within the bitmap, which corresponds to a gap
 387 * inside the reservations tree (search_start, search_len). The range
 388 * can be anything from the whole bitmap, to a gap between
 389 * reservations.
 390 *
 391 * The start value of *rstart is insignificant.
 392 *
 393 * This function searches the bitmap range starting at search_start
 394 * with length search_len for a set of contiguous free bits. We try
 395 * to find up to 'wanted' bits, but can sometimes return less.
 396 *
 397 * Returns the length of allocation, 0 if no free bits are found.
 398 *
 399 * *cstart and *clen will also be populated with the result.
 400 */
 401static int ocfs2_resmap_find_free_bits(struct ocfs2_reservation_map *resmap,
 402                                       unsigned int wanted,
 403                                       unsigned int search_start,
 404                                       unsigned int search_len,
 405                                       unsigned int *rstart,
 406                                       unsigned int *rlen)
 407{
 408        void *bitmap = resmap->m_disk_bitmap;
 409        unsigned int best_start, best_len = 0;
 410        int offset, start, found;
 411
 412        trace_ocfs2_resmap_find_free_bits_begin(search_start, search_len,
 413                                                wanted, resmap->m_bitmap_len);
 414
 415        found = best_start = best_len = 0;
 416
 417        start = search_start;
 418        while ((offset = ocfs2_find_next_zero_bit(bitmap, resmap->m_bitmap_len,
 419                                                 start)) != -1) {
 420                /* Search reached end of the region */
 421                if (offset >= (search_start + search_len))
 422                        break;
 423
 424                if (offset == start) {
 425                        /* we found a zero */
 426                        found++;
 427                        /* move start to the next bit to test */
 428                        start++;
 429                } else {
 430                        /* got a zero after some ones */
 431                        found = 1;
 432                        start = offset + 1;
 433                }
 434                if (found > best_len) {
 435                        best_len = found;
 436                        best_start = start - found;
 437                }
 438
 439                if (found >= wanted)
 440                        break;
 441        }
 442
 443        if (best_len == 0)
 444                return 0;
 445
 446        if (best_len >= wanted)
 447                best_len = wanted;
 448
 449        *rlen = best_len;
 450        *rstart = best_start;
 451
 452        trace_ocfs2_resmap_find_free_bits_end(best_start, best_len);
 453
 454        return *rlen;
 455}
 456
 457static void __ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap,
 458                                     struct ocfs2_alloc_reservation *resv,
 459                                     unsigned int goal, unsigned int wanted)
 460{
 461        struct rb_root *root = &resmap->m_reservations;
 462        unsigned int gap_start, gap_end, gap_len;
 463        struct ocfs2_alloc_reservation *prev_resv, *next_resv;
 464        struct rb_node *prev, *next;
 465        unsigned int cstart, clen;
 466        unsigned int best_start = 0, best_len = 0;
 467
 468        /*
 469         * Nasty cases to consider:
 470         *
 471         * - rbtree is empty
 472         * - our window should be first in all reservations
 473         * - our window should be last in all reservations
 474         * - need to make sure we don't go past end of bitmap
 475         */
 476        trace_ocfs2_resv_find_window_begin(resv->r_start, ocfs2_resv_end(resv),
 477                                           goal, wanted, RB_EMPTY_ROOT(root));
 478
 479        assert_spin_locked(&resv_lock);
 480
 481        if (RB_EMPTY_ROOT(root)) {
 482                /*
 483                 * Easiest case - empty tree. We can just take
 484                 * whatever window of free bits we want.
 485                 */
 486                clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal,
 487                                                   resmap->m_bitmap_len - goal,
 488                                                   &cstart, &clen);
 489
 490                /*
 491                 * This should never happen - the local alloc window
 492                 * will always have free bits when we're called.
 493                 */
 494                BUG_ON(goal == 0 && clen == 0);
 495
 496                if (clen == 0)
 497                        return;
 498
 499                resv->r_start = cstart;
 500                resv->r_len = clen;
 501
 502                ocfs2_resv_insert(resmap, resv);
 503                return;
 504        }
 505
 506        prev_resv = ocfs2_find_resv_lhs(resmap, goal);
 507
 508        if (prev_resv == NULL) {
 509                /*
 510                 * A NULL here means that the search code couldn't
 511                 * find a window that starts before goal.
 512                 *
 513                 * However, we can take the first window after goal,
 514                 * which is also by definition, the leftmost window in
 515                 * the entire tree. If we can find free bits in the
 516                 * gap between goal and the LHS window, then the
 517                 * reservation can safely be placed there.
 518                 *
 519                 * Otherwise we fall back to a linear search, checking
 520                 * the gaps in between windows for a place to
 521                 * allocate.
 522                 */
 523
 524                next = rb_first(root);
 525                next_resv = rb_entry(next, struct ocfs2_alloc_reservation,
 526                                     r_node);
 527
 528                /*
 529                 * The search should never return such a window. (see
 530                 * comment above
 531                 */
 532                if (next_resv->r_start <= goal) {
 533                        mlog(ML_ERROR, "goal: %u next_resv: start %u len %u\n",
 534                             goal, next_resv->r_start, next_resv->r_len);
 535                        ocfs2_dump_resv(resmap);
 536                        BUG();
 537                }
 538
 539                clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal,
 540                                                   next_resv->r_start - goal,
 541                                                   &cstart, &clen);
 542                if (clen) {
 543                        best_len = clen;
 544                        best_start = cstart;
 545                        if (best_len == wanted)
 546                                goto out_insert;
 547                }
 548
 549                prev_resv = next_resv;
 550                next_resv = NULL;
 551        }
 552
 553        trace_ocfs2_resv_find_window_prev(prev_resv->r_start,
 554                                          ocfs2_resv_end(prev_resv));
 555
 556        prev = &prev_resv->r_node;
 557
 558        /* Now we do a linear search for a window, starting at 'prev_rsv' */
 559        while (1) {
 560                next = rb_next(prev);
 561                if (next) {
 562                        next_resv = rb_entry(next,
 563                                             struct ocfs2_alloc_reservation,
 564                                             r_node);
 565
 566                        gap_start = ocfs2_resv_end(prev_resv) + 1;
 567                        gap_end = next_resv->r_start - 1;
 568                        gap_len = gap_end - gap_start + 1;
 569                } else {
 570                        /*
 571                         * We're at the rightmost edge of the
 572                         * tree. See if a reservation between this
 573                         * window and the end of the bitmap will work.
 574                         */
 575                        gap_start = ocfs2_resv_end(prev_resv) + 1;
 576                        gap_len = resmap->m_bitmap_len - gap_start;
 577                        gap_end = resmap->m_bitmap_len - 1;
 578                }
 579
 580                trace_ocfs2_resv_find_window_next(next ? next_resv->r_start: -1,
 581                                        next ? ocfs2_resv_end(next_resv) : -1);
 582                /*
 583                 * No need to check this gap if we have already found
 584                 * a larger region of free bits.
 585                 */
 586                if (gap_len <= best_len)
 587                        goto next_resv;
 588
 589                clen = ocfs2_resmap_find_free_bits(resmap, wanted, gap_start,
 590                                                   gap_len, &cstart, &clen);
 591                if (clen == wanted) {
 592                        best_len = clen;
 593                        best_start = cstart;
 594                        goto out_insert;
 595                } else if (clen > best_len) {
 596                        best_len = clen;
 597                        best_start = cstart;
 598                }
 599
 600next_resv:
 601                if (!next)
 602                        break;
 603
 604                prev = next;
 605                prev_resv = rb_entry(prev, struct ocfs2_alloc_reservation,
 606                                     r_node);
 607        }
 608
 609out_insert:
 610        if (best_len) {
 611                resv->r_start = best_start;
 612                resv->r_len = best_len;
 613                ocfs2_resv_insert(resmap, resv);
 614        }
 615}
 616
 617static void ocfs2_cannibalize_resv(struct ocfs2_reservation_map *resmap,
 618                                   struct ocfs2_alloc_reservation *resv,
 619                                   unsigned int wanted)
 620{
 621        struct ocfs2_alloc_reservation *lru_resv;
 622        int tmpwindow = !!(resv->r_flags & OCFS2_RESV_FLAG_TMP);
 623        unsigned int min_bits;
 624
 625        if (!tmpwindow)
 626                min_bits = ocfs2_resv_window_bits(resmap, resv) >> 1;
 627        else
 628                min_bits = wanted; /* We at know the temp window will use all
 629                                    * of these bits */
 630
 631        /*
 632         * Take the first reservation off the LRU as our 'target'. We
 633         * don't try to be smart about it. There might be a case for
 634         * searching based on size but I don't have enough data to be
 635         * sure. --Mark (3/16/2010)
 636         */
 637        lru_resv = list_first_entry(&resmap->m_lru,
 638                                    struct ocfs2_alloc_reservation, r_lru);
 639
 640        trace_ocfs2_cannibalize_resv_begin(lru_resv->r_start,
 641                                           lru_resv->r_len,
 642                                           ocfs2_resv_end(lru_resv));
 643
 644        /*
 645         * Cannibalize (some or all) of the target reservation and
 646         * feed it to the current window.
 647         */
 648        if (lru_resv->r_len <= min_bits) {
 649                /*
 650                 * Discard completely if size is less than or equal to a
 651                 * reasonable threshold - 50% of window bits for non temporary
 652                 * windows.
 653                 */
 654                resv->r_start = lru_resv->r_start;
 655                resv->r_len = lru_resv->r_len;
 656
 657                __ocfs2_resv_discard(resmap, lru_resv);
 658        } else {
 659                unsigned int shrink;
 660                if (tmpwindow)
 661                        shrink = min_bits;
 662                else
 663                        shrink = lru_resv->r_len / 2;
 664
 665                lru_resv->r_len -= shrink;
 666
 667                resv->r_start = ocfs2_resv_end(lru_resv) + 1;
 668                resv->r_len = shrink;
 669        }
 670
 671        trace_ocfs2_cannibalize_resv_end(resv->r_start, ocfs2_resv_end(resv),
 672                                         resv->r_len, resv->r_last_start,
 673                                         resv->r_last_len);
 674
 675        ocfs2_resv_insert(resmap, resv);
 676}
 677
 678static void ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap,
 679                                   struct ocfs2_alloc_reservation *resv,
 680                                   unsigned int wanted)
 681{
 682        unsigned int goal = 0;
 683
 684        BUG_ON(!ocfs2_resv_empty(resv));
 685
 686        /*
 687         * Begin by trying to get a window as close to the previous
 688         * one as possible. Using the most recent allocation as a
 689         * start goal makes sense.
 690         */
 691        if (resv->r_last_len) {
 692                goal = resv->r_last_start + resv->r_last_len;
 693                if (goal >= resmap->m_bitmap_len)
 694                        goal = 0;
 695        }
 696
 697        __ocfs2_resv_find_window(resmap, resv, goal, wanted);
 698
 699        /* Search from last alloc didn't work, try once more from beginning. */
 700        if (ocfs2_resv_empty(resv) && goal != 0)
 701                __ocfs2_resv_find_window(resmap, resv, 0, wanted);
 702
 703        if (ocfs2_resv_empty(resv)) {
 704                /*
 705                 * Still empty? Pull oldest one off the LRU, remove it from
 706                 * tree, put this one in it's place.
 707                 */
 708                ocfs2_cannibalize_resv(resmap, resv, wanted);
 709        }
 710
 711        BUG_ON(ocfs2_resv_empty(resv));
 712}
 713
 714int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
 715                           struct ocfs2_alloc_reservation *resv,
 716                           int *cstart, int *clen)
 717{
 718        if (resv == NULL || ocfs2_resmap_disabled(resmap))
 719                return -ENOSPC;
 720
 721        spin_lock(&resv_lock);
 722
 723        if (ocfs2_resv_empty(resv)) {
 724                /*
 725                 * We don't want to over-allocate for temporary
 726                 * windows. Otherwise, we run the risk of fragmenting the
 727                 * allocation space.
 728                 */
 729                unsigned int wanted = ocfs2_resv_window_bits(resmap, resv);
 730
 731                if ((resv->r_flags & OCFS2_RESV_FLAG_TMP) || wanted < *clen)
 732                        wanted = *clen;
 733
 734                /*
 735                 * Try to get a window here. If it works, we must fall
 736                 * through and test the bitmap . This avoids some
 737                 * ping-ponging of windows due to non-reserved space
 738                 * being allocation before we initialize a window for
 739                 * that inode.
 740                 */
 741                ocfs2_resv_find_window(resmap, resv, wanted);
 742                trace_ocfs2_resmap_resv_bits(resv->r_start, resv->r_len);
 743        }
 744
 745        BUG_ON(ocfs2_resv_empty(resv));
 746
 747        *cstart = resv->r_start;
 748        *clen = resv->r_len;
 749
 750        spin_unlock(&resv_lock);
 751        return 0;
 752}
 753
 754static void
 755        ocfs2_adjust_resv_from_alloc(struct ocfs2_reservation_map *resmap,
 756                                     struct ocfs2_alloc_reservation *resv,
 757                                     unsigned int start, unsigned int end)
 758{
 759        unsigned int rhs = 0;
 760        unsigned int old_end = ocfs2_resv_end(resv);
 761
 762        BUG_ON(start != resv->r_start || old_end < end);
 763
 764        /*
 765         * Completely used? We can remove it then.
 766         */
 767        if (old_end == end) {
 768                __ocfs2_resv_discard(resmap, resv);
 769                return;
 770        }
 771
 772        rhs = old_end - end;
 773
 774        /*
 775         * This should have been trapped above.
 776         */
 777        BUG_ON(rhs == 0);
 778
 779        resv->r_start = end + 1;
 780        resv->r_len = old_end - resv->r_start + 1;
 781}
 782
 783void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
 784                               struct ocfs2_alloc_reservation *resv,
 785                               u32 cstart, u32 clen)
 786{
 787        unsigned int cend = cstart + clen - 1;
 788
 789        if (resmap == NULL || ocfs2_resmap_disabled(resmap))
 790                return;
 791
 792        if (resv == NULL)
 793                return;
 794
 795        BUG_ON(cstart != resv->r_start);
 796
 797        spin_lock(&resv_lock);
 798
 799        trace_ocfs2_resmap_claimed_bits_begin(cstart, cend, clen, resv->r_start,
 800                                              ocfs2_resv_end(resv), resv->r_len,
 801                                              resv->r_last_start,
 802                                              resv->r_last_len);
 803
 804        BUG_ON(cstart < resv->r_start);
 805        BUG_ON(cstart > ocfs2_resv_end(resv));
 806        BUG_ON(cend > ocfs2_resv_end(resv));
 807
 808        ocfs2_adjust_resv_from_alloc(resmap, resv, cstart, cend);
 809        resv->r_last_start = cstart;
 810        resv->r_last_len = clen;
 811
 812        /*
 813         * May have been discarded above from
 814         * ocfs2_adjust_resv_from_alloc().
 815         */
 816        if (!ocfs2_resv_empty(resv))
 817                ocfs2_resv_mark_lru(resmap, resv);
 818
 819        trace_ocfs2_resmap_claimed_bits_end(resv->r_start, ocfs2_resv_end(resv),
 820                                            resv->r_len, resv->r_last_start,
 821                                            resv->r_last_len);
 822
 823        ocfs2_check_resmap(resmap);
 824
 825        spin_unlock(&resv_lock);
 826}
 827