fs/xfs/libxfs/xfs_rmap_btree.c

   1 /*
   2  * Copyright (c) 2014 Red Hat, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19 #include "xfs_fs.h"
  20 #include "xfs_shared.h"
  21 #include "xfs_format.h"
  22 #include "xfs_log_format.h"
  23 #include "xfs_trans_resv.h"
  24 #include "xfs_bit.h"
  25 #include "xfs_sb.h"
  26 #include "xfs_mount.h"
  27 #include "xfs_defer.h"
  28 #include "xfs_inode.h"
  29 #include "xfs_trans.h"
  30 #include "xfs_alloc.h"
  31 #include "xfs_btree.h"
  32 #include "xfs_rmap.h"
  33 #include "xfs_rmap_btree.h"
  34 #include "xfs_trace.h"
  35 #include "xfs_cksum.h"
  36 #include "xfs_error.h"
  37 #include "xfs_extent_busy.h"
  38 #include "xfs_ag_resv.h"
  39
  40 /*
  41  * Reverse map btree.
  42  *
  43  * This is a per-ag tree used to track the owner(s) of a given extent. With
  44  * reflink it is possible for there to be multiple owners, which is a departure
  45  * from classic XFS. Owner records for data extents are inserted when the
  46  * extent is mapped and removed when an extent is unmapped.  Owner records for
  47  * all other block types (i.e. metadata) are inserted when an extent is
  48  * allocated and removed when an extent is freed. There can only be one owner
  49  * of a metadata extent, usually an inode or some other metadata structure like
  50  * an AG btree.
  51  *
  52  * The rmap btree is part of the free space management, so blocks for the tree
  53  * are sourced from the agfl. Hence we need transaction reservation support for
  54  * this tree so that the freelist is always large enough. This also impacts on
  55  * the minimum space we need to leave free in the AG.
  56  *
  57  * The tree is ordered by [ag block, owner, offset]. This is a large key size,
  58  * but it is the only way to enforce unique keys when a block can be owned by
  59  * multiple files at any offset. There's no need to order/search by extent
  60  * size for online updating/management of the tree. It is intended that most
  61  * reverse lookups will be to find the owner(s) of a particular block, or to
  62  * try to recover tree and file data from corrupt primary metadata.
  63  */
  64
  65 static struct xfs_btree_cur *
  66 xfs_rmapbt_dup_cursor(
  67         struct xfs_btree_cur    *cur)
  68 {
  69         return xfs_rmapbt_init_cursor(cur->bc_mp, cur->bc_tp,
  70                         cur->bc_private.a.agbp, cur->bc_private.a.agno);
  71 }
  72
  73 STATIC void
  74 xfs_rmapbt_set_root(
  75         struct xfs_btree_cur    *cur,
  76         union xfs_btree_ptr     *ptr,
  77         int                     inc)
  78 {
  79         struct xfs_buf          *agbp = cur->bc_private.a.agbp;
  80         struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
  81         xfs_agnumber_t          seqno = be32_to_cpu(agf->agf_seqno);
  82         int                     btnum = cur->bc_btnum;
  83         struct xfs_perag        *pag = xfs_perag_get(cur->bc_mp, seqno);
  84
  85         ASSERT(ptr->s != 0);
  86
  87         agf->agf_roots[btnum] = ptr->s;
  88         be32_add_cpu(&agf->agf_levels[btnum], inc);
  89         pag->pagf_levels[btnum] += inc;
  90         xfs_perag_put(pag);
  91
  92         xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
  93 }
  94
  95 STATIC int
  96 xfs_rmapbt_alloc_block(
  97         struct xfs_btree_cur    *cur,
  98         union xfs_btree_ptr     *start,
  99         union xfs_btree_ptr     *new,
 100         int                     *stat)
 101 {
 102         struct xfs_buf          *agbp = cur->bc_private.a.agbp;
 103         struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
 104         int                     error;
 105         xfs_agblock_t           bno;
 106
 107         XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
 108
 109         /* Allocate the new block from the freelist. If we can't, give up.  */
 110         error = xfs_alloc_get_freelist(cur->bc_tp, cur->bc_private.a.agbp,
 111                                        &bno, 1);
 112         if (error) {
 113                 XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
 114                 return error;
 115         }
 116
 117         trace_xfs_rmapbt_alloc_block(cur->bc_mp, cur->bc_private.a.agno,
 118                         bno, 1);
 119         if (bno == NULLAGBLOCK) {
 120                 XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
 121                 *stat = 0;
 122                 return 0;
 123         }
 124
 125         xfs_extent_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, bno, 1,
 126                         false);
 127
 128         xfs_trans_agbtree_delta(cur->bc_tp, 1);
 129         new->s = cpu_to_be32(bno);
 130         be32_add_cpu(&agf->agf_rmap_blocks, 1);
 131         xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
 132
 133         XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
 134         *stat = 1;
 135         return 0;
 136 }
 137
 138 STATIC int
 139 xfs_rmapbt_free_block(
 140         struct xfs_btree_cur    *cur,
 141         struct xfs_buf          *bp)
 142 {
 143         struct xfs_buf          *agbp = cur->bc_private.a.agbp;
 144         struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
 145         xfs_agblock_t           bno;
 146         int                     error;
 147
 148         bno = xfs_daddr_to_agbno(cur->bc_mp, XFS_BUF_ADDR(bp));
 149         trace_xfs_rmapbt_free_block(cur->bc_mp, cur->bc_private.a.agno,
 150                         bno, 1);
 151         be32_add_cpu(&agf->agf_rmap_blocks, -1);
 152         xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
 153         error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
 154         if (error)
 155                 return error;
 156
 157         xfs_extent_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1,
 158                               XFS_EXTENT_BUSY_SKIP_DISCARD);
 159         xfs_trans_agbtree_delta(cur->bc_tp, -1);
 160
 161         return 0;
 162 }
 163
 164 STATIC int
 165 xfs_rmapbt_get_minrecs(
 166         struct xfs_btree_cur    *cur,
 167         int                     level)
 168 {
 169         return cur->bc_mp->m_rmap_mnr[level != 0];
 170 }
 171
 172 STATIC int
 173 xfs_rmapbt_get_maxrecs(
 174         struct xfs_btree_cur    *cur,
 175         int                     level)
 176 {
 177         return cur->bc_mp->m_rmap_mxr[level != 0];
 178 }
 179
 180 STATIC void
 181 xfs_rmapbt_init_key_from_rec(
 182         union xfs_btree_key     *key,
 183         union xfs_btree_rec     *rec)
 184 {
 185         key->rmap.rm_startblock = rec->rmap.rm_startblock;
 186         key->rmap.rm_owner = rec->rmap.rm_owner;
 187         key->rmap.rm_offset = rec->rmap.rm_offset;
 188 }
 189
 190 /*
 191  * The high key for a reverse mapping record can be computed by shifting
 192  * the startblock and offset to the highest value that would still map
 193  * to that record.  In practice this means that we add blockcount-1 to
 194  * the startblock for all records, and if the record is for a data/attr
 195  * fork mapping, we add blockcount-1 to the offset too.
 196  */
 197 STATIC void
 198 xfs_rmapbt_init_high_key_from_rec(
 199         union xfs_btree_key     *key,
 200         union xfs_btree_rec     *rec)
 201 {
 202         uint64_t                off;
 203         int                     adj;
 204
 205         adj = be32_to_cpu(rec->rmap.rm_blockcount) - 1;
 206
 207         key->rmap.rm_startblock = rec->rmap.rm_startblock;
 208         be32_add_cpu(&key->rmap.rm_startblock, adj);
 209         key->rmap.rm_owner = rec->rmap.rm_owner;
 210         key->rmap.rm_offset = rec->rmap.rm_offset;
 211         if (XFS_RMAP_NON_INODE_OWNER(be64_to_cpu(rec->rmap.rm_owner)) ||
 212             XFS_RMAP_IS_BMBT_BLOCK(be64_to_cpu(rec->rmap.rm_offset)))
 213                 return;
 214         off = be64_to_cpu(key->rmap.rm_offset);
 215         off = (XFS_RMAP_OFF(off) + adj) | (off & ~XFS_RMAP_OFF_MASK);
 216         key->rmap.rm_offset = cpu_to_be64(off);
 217 }
 218
 219 STATIC void
 220 xfs_rmapbt_init_rec_from_cur(
 221         struct xfs_btree_cur    *cur,
 222         union xfs_btree_rec     *rec)
 223 {
 224         rec->rmap.rm_startblock = cpu_to_be32(cur->bc_rec.r.rm_startblock);
 225         rec->rmap.rm_blockcount = cpu_to_be32(cur->bc_rec.r.rm_blockcount);
 226         rec->rmap.rm_owner = cpu_to_be64(cur->bc_rec.r.rm_owner);
 227         rec->rmap.rm_offset = cpu_to_be64(
 228                         xfs_rmap_irec_offset_pack(&cur->bc_rec.r));
 229 }
 230
 231 STATIC void
 232 xfs_rmapbt_init_ptr_from_cur(
 233         struct xfs_btree_cur    *cur,
 234         union xfs_btree_ptr     *ptr)
 235 {
 236         struct xfs_agf          *agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
 237
 238         ASSERT(cur->bc_private.a.agno == be32_to_cpu(agf->agf_seqno));
 239         ASSERT(agf->agf_roots[cur->bc_btnum] != 0);
 240
 241         ptr->s = agf->agf_roots[cur->bc_btnum];
 242 }
 243
 244 STATIC int64_t
 245 xfs_rmapbt_key_diff(
 246         struct xfs_btree_cur    *cur,
 247         union xfs_btree_key     *key)
 248 {
 249         struct xfs_rmap_irec    *rec = &cur->bc_rec.r;
 250         struct xfs_rmap_key     *kp = &key->rmap;
 251         __u64                   x, y;
 252         int64_t                 d;
 253
 254         d = (int64_t)be32_to_cpu(kp->rm_startblock) - rec->rm_startblock;
 255         if (d)
 256                 return d;
 257
 258         x = be64_to_cpu(kp->rm_owner);
 259         y = rec->rm_owner;
 260         if (x > y)
 261                 return 1;
 262         else if (y > x)
 263                 return -1;
 264
 265         x = be64_to_cpu(kp->rm_offset);
 266         y = xfs_rmap_irec_offset_pack(rec);
 267         if (x > y)
 268                 return 1;
 269         else if (y > x)
 270                 return -1;
 271         return 0;
 272 }
 273
 274 STATIC int64_t
 275 xfs_rmapbt_diff_two_keys(
 276         struct xfs_btree_cur    *cur,
 277         union xfs_btree_key     *k1,
 278         union xfs_btree_key     *k2)
 279 {
 280         struct xfs_rmap_key     *kp1 = &k1->rmap;
 281         struct xfs_rmap_key     *kp2 = &k2->rmap;
 282         int64_t                 d;
 283         __u64                   x, y;
 284
 285         d = (int64_t)be32_to_cpu(kp1->rm_startblock) -
 286                        be32_to_cpu(kp2->rm_startblock);
 287         if (d)
 288                 return d;
 289
 290         x = be64_to_cpu(kp1->rm_owner);
 291         y = be64_to_cpu(kp2->rm_owner);
 292         if (x > y)
 293                 return 1;
 294         else if (y > x)
 295                 return -1;
 296
 297         x = be64_to_cpu(kp1->rm_offset);
 298         y = be64_to_cpu(kp2->rm_offset);
 299         if (x > y)
 300                 return 1;
 301         else if (y > x)
 302                 return -1;
 303         return 0;
 304 }
 305
 306 static bool
 307 xfs_rmapbt_verify(
 308         struct xfs_buf          *bp)
 309 {
 310         struct xfs_mount        *mp = bp->b_target->bt_mount;
 311         struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
 312         struct xfs_perag        *pag = bp->b_pag;
 313         unsigned int            level;
 314
 315         /*
 316          * magic number and level verification
 317          *
 318          * During growfs operations, we can't verify the exact level or owner as
 319          * the perag is not fully initialised and hence not attached to the
 320          * buffer.  In this case, check against the maximum tree depth.
 321          *
 322          * Similarly, during log recovery we will have a perag structure
 323          * attached, but the agf information will not yet have been initialised
 324          * from the on disk AGF. Again, we can only check against maximum limits
 325          * in this case.
 326          */
 327         if (block->bb_magic != cpu_to_be32(XFS_RMAP_CRC_MAGIC))
 328                 return false;
 329
 330         if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
 331                 return false;
 332         if (!xfs_btree_sblock_v5hdr_verify(bp))
 333                 return false;
 334
 335         level = be16_to_cpu(block->bb_level);
 336         if (pag && pag->pagf_init) {
 337                 if (level >= pag->pagf_levels[XFS_BTNUM_RMAPi])
 338                         return false;
 339         } else if (level >= mp->m_rmap_maxlevels)
 340                 return false;
 341
 342         return xfs_btree_sblock_verify(bp, mp->m_rmap_mxr[level != 0]);
 343 }
 344
 345 static void
 346 xfs_rmapbt_read_verify(
 347         struct xfs_buf  *bp)
 348 {
 349         if (!xfs_btree_sblock_verify_crc(bp))
 350                 xfs_buf_ioerror(bp, -EFSBADCRC);
 351         else if (!xfs_rmapbt_verify(bp))
 352                 xfs_buf_ioerror(bp, -EFSCORRUPTED);
 353
 354         if (bp->b_error) {
 355                 trace_xfs_btree_corrupt(bp, _RET_IP_);
 356                 xfs_verifier_error(bp);
 357         }
 358 }
 359
 360 static void
 361 xfs_rmapbt_write_verify(
 362         struct xfs_buf  *bp)
 363 {
 364         if (!xfs_rmapbt_verify(bp)) {
 365                 trace_xfs_btree_corrupt(bp, _RET_IP_);
 366                 xfs_buf_ioerror(bp, -EFSCORRUPTED);
 367                 xfs_verifier_error(bp);
 368                 return;
 369         }
 370         xfs_btree_sblock_calc_crc(bp);
 371
 372 }
 373
 374 const struct xfs_buf_ops xfs_rmapbt_buf_ops = {
 375         .name                   = "xfs_rmapbt",
 376         .verify_read            = xfs_rmapbt_read_verify,
 377         .verify_write           = xfs_rmapbt_write_verify,
 378 };
 379
 380 STATIC int
 381 xfs_rmapbt_keys_inorder(
 382         struct xfs_btree_cur    *cur,
 383         union xfs_btree_key     *k1,
 384         union xfs_btree_key     *k2)
 385 {
 386         uint32_t                x;
 387         uint32_t                y;
 388         uint64_t                a;
 389         uint64_t                b;
 390
 391         x = be32_to_cpu(k1->rmap.rm_startblock);
 392         y = be32_to_cpu(k2->rmap.rm_startblock);
 393         if (x < y)
 394                 return 1;
 395         else if (x > y)
 396                 return 0;
 397         a = be64_to_cpu(k1->rmap.rm_owner);
 398         b = be64_to_cpu(k2->rmap.rm_owner);
 399         if (a < b)
 400                 return 1;
 401         else if (a > b)
 402                 return 0;
 403         a = be64_to_cpu(k1->rmap.rm_offset);
 404         b = be64_to_cpu(k2->rmap.rm_offset);
 405         if (a <= b)
 406                 return 1;
 407         return 0;
 408 }
 409
 410 STATIC int
 411 xfs_rmapbt_recs_inorder(
 412         struct xfs_btree_cur    *cur,
 413         union xfs_btree_rec     *r1,
 414         union xfs_btree_rec     *r2)
 415 {
 416         uint32_t                x;
 417         uint32_t                y;
 418         uint64_t                a;
 419         uint64_t                b;
 420
 421         x = be32_to_cpu(r1->rmap.rm_startblock);
 422         y = be32_to_cpu(r2->rmap.rm_startblock);
 423         if (x < y)
 424                 return 1;
 425         else if (x > y)
 426                 return 0;
 427         a = be64_to_cpu(r1->rmap.rm_owner);
 428         b = be64_to_cpu(r2->rmap.rm_owner);
 429         if (a < b)
 430                 return 1;
 431         else if (a > b)
 432                 return 0;
 433         a = be64_to_cpu(r1->rmap.rm_offset);
 434         b = be64_to_cpu(r2->rmap.rm_offset);
 435         if (a <= b)
 436                 return 1;
 437         return 0;
 438 }
 439
 440 static const struct xfs_btree_ops xfs_rmapbt_ops = {
 441         .rec_len                = sizeof(struct xfs_rmap_rec),
 442         .key_len                = 2 * sizeof(struct xfs_rmap_key),
 443
 444         .dup_cursor             = xfs_rmapbt_dup_cursor,
 445         .set_root               = xfs_rmapbt_set_root,
 446         .alloc_block            = xfs_rmapbt_alloc_block,
 447         .free_block             = xfs_rmapbt_free_block,
 448         .get_minrecs            = xfs_rmapbt_get_minrecs,
 449         .get_maxrecs            = xfs_rmapbt_get_maxrecs,
 450         .init_key_from_rec      = xfs_rmapbt_init_key_from_rec,
 451         .init_high_key_from_rec = xfs_rmapbt_init_high_key_from_rec,
 452         .init_rec_from_cur      = xfs_rmapbt_init_rec_from_cur,
 453         .init_ptr_from_cur      = xfs_rmapbt_init_ptr_from_cur,
 454         .key_diff               = xfs_rmapbt_key_diff,
 455         .buf_ops                = &xfs_rmapbt_buf_ops,
 456         .diff_two_keys          = xfs_rmapbt_diff_two_keys,
 457         .keys_inorder           = xfs_rmapbt_keys_inorder,
 458         .recs_inorder           = xfs_rmapbt_recs_inorder,
 459 };
 460
 461 /*
 462  * Allocate a new allocation btree cursor.
 463  */
 464 struct xfs_btree_cur *
 465 xfs_rmapbt_init_cursor(
 466         struct xfs_mount        *mp,
 467         struct xfs_trans        *tp,
 468         struct xfs_buf          *agbp,
 469         xfs_agnumber_t          agno)
 470 {
 471         struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
 472         struct xfs_btree_cur    *cur;
 473
 474         cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_NOFS);
 475         cur->bc_tp = tp;
 476         cur->bc_mp = mp;
 477         /* Overlapping btree; 2 keys per pointer. */
 478         cur->bc_btnum = XFS_BTNUM_RMAP;
 479         cur->bc_flags = XFS_BTREE_CRC_BLOCKS | XFS_BTREE_OVERLAPPING;
 480         cur->bc_blocklog = mp->m_sb.sb_blocklog;
 481         cur->bc_ops = &xfs_rmapbt_ops;
 482         cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]);
 483         cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_rmap_2);
 484
 485         cur->bc_private.a.agbp = agbp;
 486         cur->bc_private.a.agno = agno;
 487
 488         return cur;
 489 }
 490
 491 /*
 492  * Calculate number of records in an rmap btree block.
 493  */
 494 int
 495 xfs_rmapbt_maxrecs(
 496         struct xfs_mount        *mp,
 497         int                     blocklen,
 498         int                     leaf)
 499 {
 500         blocklen -= XFS_RMAP_BLOCK_LEN;
 501
 502         if (leaf)
 503                 return blocklen / sizeof(struct xfs_rmap_rec);
 504         return blocklen /
 505                 (2 * sizeof(struct xfs_rmap_key) + sizeof(xfs_rmap_ptr_t));
 506 }
 507
 508 /* Compute the maximum height of an rmap btree. */
 509 void
 510 xfs_rmapbt_compute_maxlevels(
 511         struct xfs_mount                *mp)
 512 {
 513         /*
 514          * On a non-reflink filesystem, the maximum number of rmap
 515          * records is the number of blocks in the AG, hence the max
 516          * rmapbt height is log_$maxrecs($agblocks).  However, with
 517          * reflink each AG block can have up to 2^32 (per the refcount
 518          * record format) owners, which means that theoretically we
 519          * could face up to 2^64 rmap records.
 520          *
 521          * That effectively means that the max rmapbt height must be
 522          * XFS_BTREE_MAXLEVELS.  "Fortunately" we'll run out of AG
 523          * blocks to feed the rmapbt long before the rmapbt reaches
 524          * maximum height.  The reflink code uses ag_resv_critical to
 525          * disallow reflinking when less than 10% of the per-AG metadata
 526          * block reservation since the fallback is a regular file copy.
 527          */
 528         if (xfs_sb_version_hasreflink(&mp->m_sb))
 529                 mp->m_rmap_maxlevels = XFS_BTREE_MAXLEVELS;
 530         else
 531                 mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels(mp,
 532                                 mp->m_rmap_mnr, mp->m_sb.sb_agblocks);
 533 }
 534
 535 /* Calculate the refcount btree size for some records. */
 536 xfs_extlen_t
 537 xfs_rmapbt_calc_size(
 538         struct xfs_mount        *mp,
 539         unsigned long long      len)
 540 {
 541         return xfs_btree_calc_size(mp, mp->m_rmap_mnr, len);
 542 }
 543
 544 /*
 545  * Calculate the maximum refcount btree size.
 546  */
 547 xfs_extlen_t
 548 xfs_rmapbt_max_size(
 549         struct xfs_mount        *mp,
 550         xfs_agblock_t           agblocks)
 551 {
 552         /* Bail out if we're uninitialized, which can happen in mkfs. */
 553         if (mp->m_rmap_mxr[0] == 0)
 554                 return 0;
 555
 556         return xfs_rmapbt_calc_size(mp, agblocks);
 557 }
 558
 559 /*
 560  * Figure out how many blocks to reserve and how many are used by this btree.
 561  */
 562 int
 563 xfs_rmapbt_calc_reserves(
 564         struct xfs_mount        *mp,
 565         xfs_agnumber_t          agno,
 566         xfs_extlen_t            *ask,
 567         xfs_extlen_t            *used)
 568 {
 569         struct xfs_buf          *agbp;
 570         struct xfs_agf          *agf;
 571         xfs_agblock_t           agblocks;
 572         xfs_extlen_t            tree_len;
 573         int                     error;
 574
 575         if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
 576                 return 0;
 577
 578         error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
 579         if (error)
 580                 return error;
 581
 582         agf = XFS_BUF_TO_AGF(agbp);
 583         agblocks = be32_to_cpu(agf->agf_length);
 584         tree_len = be32_to_cpu(agf->agf_rmap_blocks);
 585         xfs_buf_relse(agbp);
 586
 587         /* Reserve 1% of the AG or enough for 1 block per record. */
 588         *ask += max(agblocks / 100, xfs_rmapbt_max_size(mp, agblocks));
 589         *used += tree_len;
 590
 591         return error;
 592 }