linux/fs/xfs/xfs_mount.c
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   1/*
   2 * Copyright (c) 2000-2005 Silicon Graphics, 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_types.h"
  21#include "xfs_bit.h"
  22#include "xfs_log.h"
  23#include "xfs_inum.h"
  24#include "xfs_trans.h"
  25#include "xfs_trans_priv.h"
  26#include "xfs_sb.h"
  27#include "xfs_ag.h"
  28#include "xfs_dir2.h"
  29#include "xfs_mount.h"
  30#include "xfs_bmap_btree.h"
  31#include "xfs_alloc_btree.h"
  32#include "xfs_ialloc_btree.h"
  33#include "xfs_dinode.h"
  34#include "xfs_inode.h"
  35#include "xfs_btree.h"
  36#include "xfs_ialloc.h"
  37#include "xfs_alloc.h"
  38#include "xfs_rtalloc.h"
  39#include "xfs_bmap.h"
  40#include "xfs_error.h"
  41#include "xfs_quota.h"
  42#include "xfs_fsops.h"
  43#include "xfs_utils.h"
  44#include "xfs_trace.h"
  45#include "xfs_icache.h"
  46
  47
  48#ifdef HAVE_PERCPU_SB
  49STATIC void     xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,
  50                                                int);
  51STATIC void     xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t,
  52                                                int);
  53STATIC void     xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
  54#else
  55
  56#define xfs_icsb_balance_counter(mp, a, b)              do { } while (0)
  57#define xfs_icsb_balance_counter_locked(mp, a, b)       do { } while (0)
  58#endif
  59
  60static const struct {
  61        short offset;
  62        short type;     /* 0 = integer
  63                         * 1 = binary / string (no translation)
  64                         */
  65} xfs_sb_info[] = {
  66    { offsetof(xfs_sb_t, sb_magicnum),   0 },
  67    { offsetof(xfs_sb_t, sb_blocksize),  0 },
  68    { offsetof(xfs_sb_t, sb_dblocks),    0 },
  69    { offsetof(xfs_sb_t, sb_rblocks),    0 },
  70    { offsetof(xfs_sb_t, sb_rextents),   0 },
  71    { offsetof(xfs_sb_t, sb_uuid),       1 },
  72    { offsetof(xfs_sb_t, sb_logstart),   0 },
  73    { offsetof(xfs_sb_t, sb_rootino),    0 },
  74    { offsetof(xfs_sb_t, sb_rbmino),     0 },
  75    { offsetof(xfs_sb_t, sb_rsumino),    0 },
  76    { offsetof(xfs_sb_t, sb_rextsize),   0 },
  77    { offsetof(xfs_sb_t, sb_agblocks),   0 },
  78    { offsetof(xfs_sb_t, sb_agcount),    0 },
  79    { offsetof(xfs_sb_t, sb_rbmblocks),  0 },
  80    { offsetof(xfs_sb_t, sb_logblocks),  0 },
  81    { offsetof(xfs_sb_t, sb_versionnum), 0 },
  82    { offsetof(xfs_sb_t, sb_sectsize),   0 },
  83    { offsetof(xfs_sb_t, sb_inodesize),  0 },
  84    { offsetof(xfs_sb_t, sb_inopblock),  0 },
  85    { offsetof(xfs_sb_t, sb_fname[0]),   1 },
  86    { offsetof(xfs_sb_t, sb_blocklog),   0 },
  87    { offsetof(xfs_sb_t, sb_sectlog),    0 },
  88    { offsetof(xfs_sb_t, sb_inodelog),   0 },
  89    { offsetof(xfs_sb_t, sb_inopblog),   0 },
  90    { offsetof(xfs_sb_t, sb_agblklog),   0 },
  91    { offsetof(xfs_sb_t, sb_rextslog),   0 },
  92    { offsetof(xfs_sb_t, sb_inprogress), 0 },
  93    { offsetof(xfs_sb_t, sb_imax_pct),   0 },
  94    { offsetof(xfs_sb_t, sb_icount),     0 },
  95    { offsetof(xfs_sb_t, sb_ifree),      0 },
  96    { offsetof(xfs_sb_t, sb_fdblocks),   0 },
  97    { offsetof(xfs_sb_t, sb_frextents),  0 },
  98    { offsetof(xfs_sb_t, sb_uquotino),   0 },
  99    { offsetof(xfs_sb_t, sb_gquotino),   0 },
 100    { offsetof(xfs_sb_t, sb_qflags),     0 },
 101    { offsetof(xfs_sb_t, sb_flags),      0 },
 102    { offsetof(xfs_sb_t, sb_shared_vn),  0 },
 103    { offsetof(xfs_sb_t, sb_inoalignmt), 0 },
 104    { offsetof(xfs_sb_t, sb_unit),       0 },
 105    { offsetof(xfs_sb_t, sb_width),      0 },
 106    { offsetof(xfs_sb_t, sb_dirblklog),  0 },
 107    { offsetof(xfs_sb_t, sb_logsectlog), 0 },
 108    { offsetof(xfs_sb_t, sb_logsectsize),0 },
 109    { offsetof(xfs_sb_t, sb_logsunit),   0 },
 110    { offsetof(xfs_sb_t, sb_features2),  0 },
 111    { offsetof(xfs_sb_t, sb_bad_features2), 0 },
 112    { sizeof(xfs_sb_t),                  0 }
 113};
 114
 115static DEFINE_MUTEX(xfs_uuid_table_mutex);
 116static int xfs_uuid_table_size;
 117static uuid_t *xfs_uuid_table;
 118
 119/*
 120 * See if the UUID is unique among mounted XFS filesystems.
 121 * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
 122 */
 123STATIC int
 124xfs_uuid_mount(
 125        struct xfs_mount        *mp)
 126{
 127        uuid_t                  *uuid = &mp->m_sb.sb_uuid;
 128        int                     hole, i;
 129
 130        if (mp->m_flags & XFS_MOUNT_NOUUID)
 131                return 0;
 132
 133        if (uuid_is_nil(uuid)) {
 134                xfs_warn(mp, "Filesystem has nil UUID - can't mount");
 135                return XFS_ERROR(EINVAL);
 136        }
 137
 138        mutex_lock(&xfs_uuid_table_mutex);
 139        for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
 140                if (uuid_is_nil(&xfs_uuid_table[i])) {
 141                        hole = i;
 142                        continue;
 143                }
 144                if (uuid_equal(uuid, &xfs_uuid_table[i]))
 145                        goto out_duplicate;
 146        }
 147
 148        if (hole < 0) {
 149                xfs_uuid_table = kmem_realloc(xfs_uuid_table,
 150                        (xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
 151                        xfs_uuid_table_size  * sizeof(*xfs_uuid_table),
 152                        KM_SLEEP);
 153                hole = xfs_uuid_table_size++;
 154        }
 155        xfs_uuid_table[hole] = *uuid;
 156        mutex_unlock(&xfs_uuid_table_mutex);
 157
 158        return 0;
 159
 160 out_duplicate:
 161        mutex_unlock(&xfs_uuid_table_mutex);
 162        xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
 163        return XFS_ERROR(EINVAL);
 164}
 165
 166STATIC void
 167xfs_uuid_unmount(
 168        struct xfs_mount        *mp)
 169{
 170        uuid_t                  *uuid = &mp->m_sb.sb_uuid;
 171        int                     i;
 172
 173        if (mp->m_flags & XFS_MOUNT_NOUUID)
 174                return;
 175
 176        mutex_lock(&xfs_uuid_table_mutex);
 177        for (i = 0; i < xfs_uuid_table_size; i++) {
 178                if (uuid_is_nil(&xfs_uuid_table[i]))
 179                        continue;
 180                if (!uuid_equal(uuid, &xfs_uuid_table[i]))
 181                        continue;
 182                memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
 183                break;
 184        }
 185        ASSERT(i < xfs_uuid_table_size);
 186        mutex_unlock(&xfs_uuid_table_mutex);
 187}
 188
 189
 190/*
 191 * Reference counting access wrappers to the perag structures.
 192 * Because we never free per-ag structures, the only thing we
 193 * have to protect against changes is the tree structure itself.
 194 */
 195struct xfs_perag *
 196xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
 197{
 198        struct xfs_perag        *pag;
 199        int                     ref = 0;
 200
 201        rcu_read_lock();
 202        pag = radix_tree_lookup(&mp->m_perag_tree, agno);
 203        if (pag) {
 204                ASSERT(atomic_read(&pag->pag_ref) >= 0);
 205                ref = atomic_inc_return(&pag->pag_ref);
 206        }
 207        rcu_read_unlock();
 208        trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
 209        return pag;
 210}
 211
 212/*
 213 * search from @first to find the next perag with the given tag set.
 214 */
 215struct xfs_perag *
 216xfs_perag_get_tag(
 217        struct xfs_mount        *mp,
 218        xfs_agnumber_t          first,
 219        int                     tag)
 220{
 221        struct xfs_perag        *pag;
 222        int                     found;
 223        int                     ref;
 224
 225        rcu_read_lock();
 226        found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
 227                                        (void **)&pag, first, 1, tag);
 228        if (found <= 0) {
 229                rcu_read_unlock();
 230                return NULL;
 231        }
 232        ref = atomic_inc_return(&pag->pag_ref);
 233        rcu_read_unlock();
 234        trace_xfs_perag_get_tag(mp, pag->pag_agno, ref, _RET_IP_);
 235        return pag;
 236}
 237
 238void
 239xfs_perag_put(struct xfs_perag *pag)
 240{
 241        int     ref;
 242
 243        ASSERT(atomic_read(&pag->pag_ref) > 0);
 244        ref = atomic_dec_return(&pag->pag_ref);
 245        trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
 246}
 247
 248STATIC void
 249__xfs_free_perag(
 250        struct rcu_head *head)
 251{
 252        struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
 253
 254        ASSERT(atomic_read(&pag->pag_ref) == 0);
 255        kmem_free(pag);
 256}
 257
 258/*
 259 * Free up the per-ag resources associated with the mount structure.
 260 */
 261STATIC void
 262xfs_free_perag(
 263        xfs_mount_t     *mp)
 264{
 265        xfs_agnumber_t  agno;
 266        struct xfs_perag *pag;
 267
 268        for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
 269                spin_lock(&mp->m_perag_lock);
 270                pag = radix_tree_delete(&mp->m_perag_tree, agno);
 271                spin_unlock(&mp->m_perag_lock);
 272                ASSERT(pag);
 273                ASSERT(atomic_read(&pag->pag_ref) == 0);
 274                call_rcu(&pag->rcu_head, __xfs_free_perag);
 275        }
 276}
 277
 278/*
 279 * Check size of device based on the (data/realtime) block count.
 280 * Note: this check is used by the growfs code as well as mount.
 281 */
 282int
 283xfs_sb_validate_fsb_count(
 284        xfs_sb_t        *sbp,
 285        __uint64_t      nblocks)
 286{
 287        ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
 288        ASSERT(sbp->sb_blocklog >= BBSHIFT);
 289
 290#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
 291        if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
 292                return EFBIG;
 293#else                  /* Limited by UINT_MAX of sectors */
 294        if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
 295                return EFBIG;
 296#endif
 297        return 0;
 298}
 299
 300/*
 301 * Check the validity of the SB found.
 302 */
 303STATIC int
 304xfs_mount_validate_sb(
 305        xfs_mount_t     *mp,
 306        xfs_sb_t        *sbp,
 307        bool            check_inprogress)
 308{
 309
 310        /*
 311         * If the log device and data device have the
 312         * same device number, the log is internal.
 313         * Consequently, the sb_logstart should be non-zero.  If
 314         * we have a zero sb_logstart in this case, we may be trying to mount
 315         * a volume filesystem in a non-volume manner.
 316         */
 317        if (sbp->sb_magicnum != XFS_SB_MAGIC) {
 318                xfs_warn(mp, "bad magic number");
 319                return XFS_ERROR(EWRONGFS);
 320        }
 321
 322        if (!xfs_sb_good_version(sbp)) {
 323                xfs_warn(mp, "bad version");
 324                return XFS_ERROR(EWRONGFS);
 325        }
 326
 327        if (unlikely(
 328            sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
 329                xfs_warn(mp,
 330                "filesystem is marked as having an external log; "
 331                "specify logdev on the mount command line.");
 332                return XFS_ERROR(EINVAL);
 333        }
 334
 335        if (unlikely(
 336            sbp->sb_logstart != 0 && mp->m_logdev_targp != mp->m_ddev_targp)) {
 337                xfs_warn(mp,
 338                "filesystem is marked as having an internal log; "
 339                "do not specify logdev on the mount command line.");
 340                return XFS_ERROR(EINVAL);
 341        }
 342
 343        /*
 344         * More sanity checking.  Most of these were stolen directly from
 345         * xfs_repair.
 346         */
 347        if (unlikely(
 348            sbp->sb_agcount <= 0                                        ||
 349            sbp->sb_sectsize < XFS_MIN_SECTORSIZE                       ||
 350            sbp->sb_sectsize > XFS_MAX_SECTORSIZE                       ||
 351            sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG                    ||
 352            sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG                    ||
 353            sbp->sb_sectsize != (1 << sbp->sb_sectlog)                  ||
 354            sbp->sb_blocksize < XFS_MIN_BLOCKSIZE                       ||
 355            sbp->sb_blocksize > XFS_MAX_BLOCKSIZE                       ||
 356            sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG                    ||
 357            sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG                    ||
 358            sbp->sb_blocksize != (1 << sbp->sb_blocklog)                ||
 359            sbp->sb_inodesize < XFS_DINODE_MIN_SIZE                     ||
 360            sbp->sb_inodesize > XFS_DINODE_MAX_SIZE                     ||
 361            sbp->sb_inodelog < XFS_DINODE_MIN_LOG                       ||
 362            sbp->sb_inodelog > XFS_DINODE_MAX_LOG                       ||
 363            sbp->sb_inodesize != (1 << sbp->sb_inodelog)                ||
 364            (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)   ||
 365            (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)  ||
 366            (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)  ||
 367            (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */)    ||
 368            sbp->sb_dblocks == 0                                        ||
 369            sbp->sb_dblocks > XFS_MAX_DBLOCKS(sbp)                      ||
 370            sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp))) {
 371                XFS_CORRUPTION_ERROR("SB sanity check failed",
 372                                XFS_ERRLEVEL_LOW, mp, sbp);
 373                return XFS_ERROR(EFSCORRUPTED);
 374        }
 375
 376        /*
 377         * Until this is fixed only page-sized or smaller data blocks work.
 378         */
 379        if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
 380                xfs_warn(mp,
 381                "File system with blocksize %d bytes. "
 382                "Only pagesize (%ld) or less will currently work.",
 383                                sbp->sb_blocksize, PAGE_SIZE);
 384                return XFS_ERROR(ENOSYS);
 385        }
 386
 387        /*
 388         * Currently only very few inode sizes are supported.
 389         */
 390        switch (sbp->sb_inodesize) {
 391        case 256:
 392        case 512:
 393        case 1024:
 394        case 2048:
 395                break;
 396        default:
 397                xfs_warn(mp, "inode size of %d bytes not supported",
 398                                sbp->sb_inodesize);
 399                return XFS_ERROR(ENOSYS);
 400        }
 401
 402        if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
 403            xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
 404                xfs_warn(mp,
 405                "file system too large to be mounted on this system.");
 406                return XFS_ERROR(EFBIG);
 407        }
 408
 409        if (check_inprogress && sbp->sb_inprogress) {
 410                xfs_warn(mp, "Offline file system operation in progress!");
 411                return XFS_ERROR(EFSCORRUPTED);
 412        }
 413
 414        /*
 415         * Version 1 directory format has never worked on Linux.
 416         */
 417        if (unlikely(!xfs_sb_version_hasdirv2(sbp))) {
 418                xfs_warn(mp, "file system using version 1 directory format");
 419                return XFS_ERROR(ENOSYS);
 420        }
 421
 422        return 0;
 423}
 424
 425int
 426xfs_initialize_perag(
 427        xfs_mount_t     *mp,
 428        xfs_agnumber_t  agcount,
 429        xfs_agnumber_t  *maxagi)
 430{
 431        xfs_agnumber_t  index;
 432        xfs_agnumber_t  first_initialised = 0;
 433        xfs_perag_t     *pag;
 434        xfs_agino_t     agino;
 435        xfs_ino_t       ino;
 436        xfs_sb_t        *sbp = &mp->m_sb;
 437        int             error = -ENOMEM;
 438
 439        /*
 440         * Walk the current per-ag tree so we don't try to initialise AGs
 441         * that already exist (growfs case). Allocate and insert all the
 442         * AGs we don't find ready for initialisation.
 443         */
 444        for (index = 0; index < agcount; index++) {
 445                pag = xfs_perag_get(mp, index);
 446                if (pag) {
 447                        xfs_perag_put(pag);
 448                        continue;
 449                }
 450                if (!first_initialised)
 451                        first_initialised = index;
 452
 453                pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
 454                if (!pag)
 455                        goto out_unwind;
 456                pag->pag_agno = index;
 457                pag->pag_mount = mp;
 458                spin_lock_init(&pag->pag_ici_lock);
 459                mutex_init(&pag->pag_ici_reclaim_lock);
 460                INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
 461                spin_lock_init(&pag->pag_buf_lock);
 462                pag->pag_buf_tree = RB_ROOT;
 463
 464                if (radix_tree_preload(GFP_NOFS))
 465                        goto out_unwind;
 466
 467                spin_lock(&mp->m_perag_lock);
 468                if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
 469                        BUG();
 470                        spin_unlock(&mp->m_perag_lock);
 471                        radix_tree_preload_end();
 472                        error = -EEXIST;
 473                        goto out_unwind;
 474                }
 475                spin_unlock(&mp->m_perag_lock);
 476                radix_tree_preload_end();
 477        }
 478
 479        /*
 480         * If we mount with the inode64 option, or no inode overflows
 481         * the legacy 32-bit address space clear the inode32 option.
 482         */
 483        agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
 484        ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
 485
 486        if ((mp->m_flags & XFS_MOUNT_SMALL_INUMS) && ino > XFS_MAXINUMBER_32)
 487                mp->m_flags |= XFS_MOUNT_32BITINODES;
 488        else
 489                mp->m_flags &= ~XFS_MOUNT_32BITINODES;
 490
 491        if (mp->m_flags & XFS_MOUNT_32BITINODES)
 492                index = xfs_set_inode32(mp);
 493        else
 494                index = xfs_set_inode64(mp);
 495
 496        if (maxagi)
 497                *maxagi = index;
 498        return 0;
 499
 500out_unwind:
 501        kmem_free(pag);
 502        for (; index > first_initialised; index--) {
 503                pag = radix_tree_delete(&mp->m_perag_tree, index);
 504                kmem_free(pag);
 505        }
 506        return error;
 507}
 508
 509void
 510xfs_sb_from_disk(
 511        struct xfs_sb   *to,
 512        xfs_dsb_t       *from)
 513{
 514        to->sb_magicnum = be32_to_cpu(from->sb_magicnum);
 515        to->sb_blocksize = be32_to_cpu(from->sb_blocksize);
 516        to->sb_dblocks = be64_to_cpu(from->sb_dblocks);
 517        to->sb_rblocks = be64_to_cpu(from->sb_rblocks);
 518        to->sb_rextents = be64_to_cpu(from->sb_rextents);
 519        memcpy(&to->sb_uuid, &from->sb_uuid, sizeof(to->sb_uuid));
 520        to->sb_logstart = be64_to_cpu(from->sb_logstart);
 521        to->sb_rootino = be64_to_cpu(from->sb_rootino);
 522        to->sb_rbmino = be64_to_cpu(from->sb_rbmino);
 523        to->sb_rsumino = be64_to_cpu(from->sb_rsumino);
 524        to->sb_rextsize = be32_to_cpu(from->sb_rextsize);
 525        to->sb_agblocks = be32_to_cpu(from->sb_agblocks);
 526        to->sb_agcount = be32_to_cpu(from->sb_agcount);
 527        to->sb_rbmblocks = be32_to_cpu(from->sb_rbmblocks);
 528        to->sb_logblocks = be32_to_cpu(from->sb_logblocks);
 529        to->sb_versionnum = be16_to_cpu(from->sb_versionnum);
 530        to->sb_sectsize = be16_to_cpu(from->sb_sectsize);
 531        to->sb_inodesize = be16_to_cpu(from->sb_inodesize);
 532        to->sb_inopblock = be16_to_cpu(from->sb_inopblock);
 533        memcpy(&to->sb_fname, &from->sb_fname, sizeof(to->sb_fname));
 534        to->sb_blocklog = from->sb_blocklog;
 535        to->sb_sectlog = from->sb_sectlog;
 536        to->sb_inodelog = from->sb_inodelog;
 537        to->sb_inopblog = from->sb_inopblog;
 538        to->sb_agblklog = from->sb_agblklog;
 539        to->sb_rextslog = from->sb_rextslog;
 540        to->sb_inprogress = from->sb_inprogress;
 541        to->sb_imax_pct = from->sb_imax_pct;
 542        to->sb_icount = be64_to_cpu(from->sb_icount);
 543        to->sb_ifree = be64_to_cpu(from->sb_ifree);
 544        to->sb_fdblocks = be64_to_cpu(from->sb_fdblocks);
 545        to->sb_frextents = be64_to_cpu(from->sb_frextents);
 546        to->sb_uquotino = be64_to_cpu(from->sb_uquotino);
 547        to->sb_gquotino = be64_to_cpu(from->sb_gquotino);
 548        to->sb_qflags = be16_to_cpu(from->sb_qflags);
 549        to->sb_flags = from->sb_flags;
 550        to->sb_shared_vn = from->sb_shared_vn;
 551        to->sb_inoalignmt = be32_to_cpu(from->sb_inoalignmt);
 552        to->sb_unit = be32_to_cpu(from->sb_unit);
 553        to->sb_width = be32_to_cpu(from->sb_width);
 554        to->sb_dirblklog = from->sb_dirblklog;
 555        to->sb_logsectlog = from->sb_logsectlog;
 556        to->sb_logsectsize = be16_to_cpu(from->sb_logsectsize);
 557        to->sb_logsunit = be32_to_cpu(from->sb_logsunit);
 558        to->sb_features2 = be32_to_cpu(from->sb_features2);
 559        to->sb_bad_features2 = be32_to_cpu(from->sb_bad_features2);
 560}
 561
 562/*
 563 * Copy in core superblock to ondisk one.
 564 *
 565 * The fields argument is mask of superblock fields to copy.
 566 */
 567void
 568xfs_sb_to_disk(
 569        xfs_dsb_t       *to,
 570        xfs_sb_t        *from,
 571        __int64_t       fields)
 572{
 573        xfs_caddr_t     to_ptr = (xfs_caddr_t)to;
 574        xfs_caddr_t     from_ptr = (xfs_caddr_t)from;
 575        xfs_sb_field_t  f;
 576        int             first;
 577        int             size;
 578
 579        ASSERT(fields);
 580        if (!fields)
 581                return;
 582
 583        while (fields) {
 584                f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
 585                first = xfs_sb_info[f].offset;
 586                size = xfs_sb_info[f + 1].offset - first;
 587
 588                ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
 589
 590                if (size == 1 || xfs_sb_info[f].type == 1) {
 591                        memcpy(to_ptr + first, from_ptr + first, size);
 592                } else {
 593                        switch (size) {
 594                        case 2:
 595                                *(__be16 *)(to_ptr + first) =
 596                                        cpu_to_be16(*(__u16 *)(from_ptr + first));
 597                                break;
 598                        case 4:
 599                                *(__be32 *)(to_ptr + first) =
 600                                        cpu_to_be32(*(__u32 *)(from_ptr + first));
 601                                break;
 602                        case 8:
 603                                *(__be64 *)(to_ptr + first) =
 604                                        cpu_to_be64(*(__u64 *)(from_ptr + first));
 605                                break;
 606                        default:
 607                                ASSERT(0);
 608                        }
 609                }
 610
 611                fields &= ~(1LL << f);
 612        }
 613}
 614
 615static void
 616xfs_sb_verify(
 617        struct xfs_buf  *bp)
 618{
 619        struct xfs_mount *mp = bp->b_target->bt_mount;
 620        struct xfs_sb   sb;
 621        int             error;
 622
 623        xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp));
 624
 625        /*
 626         * Only check the in progress field for the primary superblock as
 627         * mkfs.xfs doesn't clear it from secondary superblocks.
 628         */
 629        error = xfs_mount_validate_sb(mp, &sb, bp->b_bn == XFS_SB_DADDR);
 630        if (error)
 631                xfs_buf_ioerror(bp, error);
 632}
 633
 634static void
 635xfs_sb_read_verify(
 636        struct xfs_buf  *bp)
 637{
 638        xfs_sb_verify(bp);
 639}
 640
 641/*
 642 * We may be probed for a filesystem match, so we may not want to emit
 643 * messages when the superblock buffer is not actually an XFS superblock.
 644 * If we find an XFS superblock, the run a normal, noisy mount because we are
 645 * really going to mount it and want to know about errors.
 646 */
 647static void
 648xfs_sb_quiet_read_verify(
 649        struct xfs_buf  *bp)
 650{
 651        struct xfs_sb   sb;
 652
 653        xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp));
 654
 655        if (sb.sb_magicnum == XFS_SB_MAGIC) {
 656                /* XFS filesystem, verify noisily! */
 657                xfs_sb_read_verify(bp);
 658                return;
 659        }
 660        /* quietly fail */
 661        xfs_buf_ioerror(bp, EWRONGFS);
 662}
 663
 664static void
 665xfs_sb_write_verify(
 666        struct xfs_buf  *bp)
 667{
 668        xfs_sb_verify(bp);
 669}
 670
 671const struct xfs_buf_ops xfs_sb_buf_ops = {
 672        .verify_read = xfs_sb_read_verify,
 673        .verify_write = xfs_sb_write_verify,
 674};
 675
 676static const struct xfs_buf_ops xfs_sb_quiet_buf_ops = {
 677        .verify_read = xfs_sb_quiet_read_verify,
 678        .verify_write = xfs_sb_write_verify,
 679};
 680
 681/*
 682 * xfs_readsb
 683 *
 684 * Does the initial read of the superblock.
 685 */
 686int
 687xfs_readsb(xfs_mount_t *mp, int flags)
 688{
 689        unsigned int    sector_size;
 690        xfs_buf_t       *bp;
 691        int             error;
 692        int             loud = !(flags & XFS_MFSI_QUIET);
 693
 694        ASSERT(mp->m_sb_bp == NULL);
 695        ASSERT(mp->m_ddev_targp != NULL);
 696
 697        /*
 698         * Allocate a (locked) buffer to hold the superblock.
 699         * This will be kept around at all times to optimize
 700         * access to the superblock.
 701         */
 702        sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
 703
 704reread:
 705        bp = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,
 706                                   BTOBB(sector_size), 0,
 707                                   loud ? &xfs_sb_buf_ops
 708                                        : &xfs_sb_quiet_buf_ops);
 709        if (!bp) {
 710                if (loud)
 711                        xfs_warn(mp, "SB buffer read failed");
 712                return EIO;
 713        }
 714        if (bp->b_error) {
 715                error = bp->b_error;
 716                if (loud)
 717                        xfs_warn(mp, "SB validate failed");
 718                goto release_buf;
 719        }
 720
 721        /*
 722         * Initialize the mount structure from the superblock.
 723         */
 724        xfs_sb_from_disk(&mp->m_sb, XFS_BUF_TO_SBP(bp));
 725
 726        /*
 727         * We must be able to do sector-sized and sector-aligned IO.
 728         */
 729        if (sector_size > mp->m_sb.sb_sectsize) {
 730                if (loud)
 731                        xfs_warn(mp, "device supports %u byte sectors (not %u)",
 732                                sector_size, mp->m_sb.sb_sectsize);
 733                error = ENOSYS;
 734                goto release_buf;
 735        }
 736
 737        /*
 738         * If device sector size is smaller than the superblock size,
 739         * re-read the superblock so the buffer is correctly sized.
 740         */
 741        if (sector_size < mp->m_sb.sb_sectsize) {
 742                xfs_buf_relse(bp);
 743                sector_size = mp->m_sb.sb_sectsize;
 744                goto reread;
 745        }
 746
 747        /* Initialize per-cpu counters */
 748        xfs_icsb_reinit_counters(mp);
 749
 750        mp->m_sb_bp = bp;
 751        xfs_buf_unlock(bp);
 752        return 0;
 753
 754release_buf:
 755        xfs_buf_relse(bp);
 756        return error;
 757}
 758
 759
 760/*
 761 * xfs_mount_common
 762 *
 763 * Mount initialization code establishing various mount
 764 * fields from the superblock associated with the given
 765 * mount structure
 766 */
 767STATIC void
 768xfs_mount_common(xfs_mount_t *mp, xfs_sb_t *sbp)
 769{
 770        mp->m_agfrotor = mp->m_agirotor = 0;
 771        spin_lock_init(&mp->m_agirotor_lock);
 772        mp->m_maxagi = mp->m_sb.sb_agcount;
 773        mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
 774        mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;
 775        mp->m_sectbb_log = sbp->sb_sectlog - BBSHIFT;
 776        mp->m_agno_log = xfs_highbit32(sbp->sb_agcount - 1) + 1;
 777        mp->m_agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
 778        mp->m_blockmask = sbp->sb_blocksize - 1;
 779        mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
 780        mp->m_blockwmask = mp->m_blockwsize - 1;
 781
 782        mp->m_alloc_mxr[0] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 1);
 783        mp->m_alloc_mxr[1] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 0);
 784        mp->m_alloc_mnr[0] = mp->m_alloc_mxr[0] / 2;
 785        mp->m_alloc_mnr[1] = mp->m_alloc_mxr[1] / 2;
 786
 787        mp->m_inobt_mxr[0] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 1);
 788        mp->m_inobt_mxr[1] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 0);
 789        mp->m_inobt_mnr[0] = mp->m_inobt_mxr[0] / 2;
 790        mp->m_inobt_mnr[1] = mp->m_inobt_mxr[1] / 2;
 791
 792        mp->m_bmap_dmxr[0] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 1);
 793        mp->m_bmap_dmxr[1] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 0);
 794        mp->m_bmap_dmnr[0] = mp->m_bmap_dmxr[0] / 2;
 795        mp->m_bmap_dmnr[1] = mp->m_bmap_dmxr[1] / 2;
 796
 797        mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
 798        mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
 799                                        sbp->sb_inopblock);
 800        mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
 801}
 802
 803/*
 804 * xfs_initialize_perag_data
 805 *
 806 * Read in each per-ag structure so we can count up the number of
 807 * allocated inodes, free inodes and used filesystem blocks as this
 808 * information is no longer persistent in the superblock. Once we have
 809 * this information, write it into the in-core superblock structure.
 810 */
 811STATIC int
 812xfs_initialize_perag_data(xfs_mount_t *mp, xfs_agnumber_t agcount)
 813{
 814        xfs_agnumber_t  index;
 815        xfs_perag_t     *pag;
 816        xfs_sb_t        *sbp = &mp->m_sb;
 817        uint64_t        ifree = 0;
 818        uint64_t        ialloc = 0;
 819        uint64_t        bfree = 0;
 820        uint64_t        bfreelst = 0;
 821        uint64_t        btree = 0;
 822        int             error;
 823
 824        for (index = 0; index < agcount; index++) {
 825                /*
 826                 * read the agf, then the agi. This gets us
 827                 * all the information we need and populates the
 828                 * per-ag structures for us.
 829                 */
 830                error = xfs_alloc_pagf_init(mp, NULL, index, 0);
 831                if (error)
 832                        return error;
 833
 834                error = xfs_ialloc_pagi_init(mp, NULL, index);
 835                if (error)
 836                        return error;
 837                pag = xfs_perag_get(mp, index);
 838                ifree += pag->pagi_freecount;
 839                ialloc += pag->pagi_count;
 840                bfree += pag->pagf_freeblks;
 841                bfreelst += pag->pagf_flcount;
 842                btree += pag->pagf_btreeblks;
 843                xfs_perag_put(pag);
 844        }
 845        /*
 846         * Overwrite incore superblock counters with just-read data
 847         */
 848        spin_lock(&mp->m_sb_lock);
 849        sbp->sb_ifree = ifree;
 850        sbp->sb_icount = ialloc;
 851        sbp->sb_fdblocks = bfree + bfreelst + btree;
 852        spin_unlock(&mp->m_sb_lock);
 853
 854        /* Fixup the per-cpu counters as well. */
 855        xfs_icsb_reinit_counters(mp);
 856
 857        return 0;
 858}
 859
 860/*
 861 * Update alignment values based on mount options and sb values
 862 */
 863STATIC int
 864xfs_update_alignment(xfs_mount_t *mp)
 865{
 866        xfs_sb_t        *sbp = &(mp->m_sb);
 867
 868        if (mp->m_dalign) {
 869                /*
 870                 * If stripe unit and stripe width are not multiples
 871                 * of the fs blocksize turn off alignment.
 872                 */
 873                if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
 874                    (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
 875                        if (mp->m_flags & XFS_MOUNT_RETERR) {
 876                                xfs_warn(mp, "alignment check failed: "
 877                                         "(sunit/swidth vs. blocksize)");
 878                                return XFS_ERROR(EINVAL);
 879                        }
 880                        mp->m_dalign = mp->m_swidth = 0;
 881                } else {
 882                        /*
 883                         * Convert the stripe unit and width to FSBs.
 884                         */
 885                        mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
 886                        if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
 887                                if (mp->m_flags & XFS_MOUNT_RETERR) {
 888                                        xfs_warn(mp, "alignment check failed: "
 889                                                 "(sunit/swidth vs. ag size)");
 890                                        return XFS_ERROR(EINVAL);
 891                                }
 892                                xfs_warn(mp,
 893                "stripe alignment turned off: sunit(%d)/swidth(%d) "
 894                "incompatible with agsize(%d)",
 895                                        mp->m_dalign, mp->m_swidth,
 896                                        sbp->sb_agblocks);
 897
 898                                mp->m_dalign = 0;
 899                                mp->m_swidth = 0;
 900                        } else if (mp->m_dalign) {
 901                                mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
 902                        } else {
 903                                if (mp->m_flags & XFS_MOUNT_RETERR) {
 904                                        xfs_warn(mp, "alignment check failed: "
 905                                                "sunit(%d) less than bsize(%d)",
 906                                                mp->m_dalign,
 907                                                mp->m_blockmask +1);
 908                                        return XFS_ERROR(EINVAL);
 909                                }
 910                                mp->m_swidth = 0;
 911                        }
 912                }
 913
 914                /*
 915                 * Update superblock with new values
 916                 * and log changes
 917                 */
 918                if (xfs_sb_version_hasdalign(sbp)) {
 919                        if (sbp->sb_unit != mp->m_dalign) {
 920                                sbp->sb_unit = mp->m_dalign;
 921                                mp->m_update_flags |= XFS_SB_UNIT;
 922                        }
 923                        if (sbp->sb_width != mp->m_swidth) {
 924                                sbp->sb_width = mp->m_swidth;
 925                                mp->m_update_flags |= XFS_SB_WIDTH;
 926                        }
 927                }
 928        } else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
 929                    xfs_sb_version_hasdalign(&mp->m_sb)) {
 930                        mp->m_dalign = sbp->sb_unit;
 931                        mp->m_swidth = sbp->sb_width;
 932        }
 933
 934        return 0;
 935}
 936
 937/*
 938 * Set the maximum inode count for this filesystem
 939 */
 940STATIC void
 941xfs_set_maxicount(xfs_mount_t *mp)
 942{
 943        xfs_sb_t        *sbp = &(mp->m_sb);
 944        __uint64_t      icount;
 945
 946        if (sbp->sb_imax_pct) {
 947                /*
 948                 * Make sure the maximum inode count is a multiple
 949                 * of the units we allocate inodes in.
 950                 */
 951                icount = sbp->sb_dblocks * sbp->sb_imax_pct;
 952                do_div(icount, 100);
 953                do_div(icount, mp->m_ialloc_blks);
 954                mp->m_maxicount = (icount * mp->m_ialloc_blks)  <<
 955                                   sbp->sb_inopblog;
 956        } else {
 957                mp->m_maxicount = 0;
 958        }
 959}
 960
 961/*
 962 * Set the default minimum read and write sizes unless
 963 * already specified in a mount option.
 964 * We use smaller I/O sizes when the file system
 965 * is being used for NFS service (wsync mount option).
 966 */
 967STATIC void
 968xfs_set_rw_sizes(xfs_mount_t *mp)
 969{
 970        xfs_sb_t        *sbp = &(mp->m_sb);
 971        int             readio_log, writeio_log;
 972
 973        if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
 974                if (mp->m_flags & XFS_MOUNT_WSYNC) {
 975                        readio_log = XFS_WSYNC_READIO_LOG;
 976                        writeio_log = XFS_WSYNC_WRITEIO_LOG;
 977                } else {
 978                        readio_log = XFS_READIO_LOG_LARGE;
 979                        writeio_log = XFS_WRITEIO_LOG_LARGE;
 980                }
 981        } else {
 982                readio_log = mp->m_readio_log;
 983                writeio_log = mp->m_writeio_log;
 984        }
 985
 986        if (sbp->sb_blocklog > readio_log) {
 987                mp->m_readio_log = sbp->sb_blocklog;
 988        } else {
 989                mp->m_readio_log = readio_log;
 990        }
 991        mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
 992        if (sbp->sb_blocklog > writeio_log) {
 993                mp->m_writeio_log = sbp->sb_blocklog;
 994        } else {
 995                mp->m_writeio_log = writeio_log;
 996        }
 997        mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
 998}
 999
1000/*
1001 * precalculate the low space thresholds for dynamic speculative preallocation.
1002 */
1003void
1004xfs_set_low_space_thresholds(
1005        struct xfs_mount        *mp)
1006{
1007        int i;
1008
1009        for (i = 0; i < XFS_LOWSP_MAX; i++) {
1010                __uint64_t space = mp->m_sb.sb_dblocks;
1011
1012                do_div(space, 100);
1013                mp->m_low_space[i] = space * (i + 1);
1014        }
1015}
1016
1017
1018/*
1019 * Set whether we're using inode alignment.
1020 */
1021STATIC void
1022xfs_set_inoalignment(xfs_mount_t *mp)
1023{
1024        if (xfs_sb_version_hasalign(&mp->m_sb) &&
1025            mp->m_sb.sb_inoalignmt >=
1026            XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
1027                mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
1028        else
1029                mp->m_inoalign_mask = 0;
1030        /*
1031         * If we are using stripe alignment, check whether
1032         * the stripe unit is a multiple of the inode alignment
1033         */
1034        if (mp->m_dalign && mp->m_inoalign_mask &&
1035            !(mp->m_dalign & mp->m_inoalign_mask))
1036                mp->m_sinoalign = mp->m_dalign;
1037        else
1038                mp->m_sinoalign = 0;
1039}
1040
1041/*
1042 * Check that the data (and log if separate) are an ok size.
1043 */
1044STATIC int
1045xfs_check_sizes(xfs_mount_t *mp)
1046{
1047        xfs_buf_t       *bp;
1048        xfs_daddr_t     d;
1049
1050        d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
1051        if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
1052                xfs_warn(mp, "filesystem size mismatch detected");
1053                return XFS_ERROR(EFBIG);
1054        }
1055        bp = xfs_buf_read_uncached(mp->m_ddev_targp,
1056                                        d - XFS_FSS_TO_BB(mp, 1),
1057                                        XFS_FSS_TO_BB(mp, 1), 0, NULL);
1058        if (!bp) {
1059                xfs_warn(mp, "last sector read failed");
1060                return EIO;
1061        }
1062        xfs_buf_relse(bp);
1063
1064        if (mp->m_logdev_targp != mp->m_ddev_targp) {
1065                d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
1066                if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
1067                        xfs_warn(mp, "log size mismatch detected");
1068                        return XFS_ERROR(EFBIG);
1069                }
1070                bp = xfs_buf_read_uncached(mp->m_logdev_targp,
1071                                        d - XFS_FSB_TO_BB(mp, 1),
1072                                        XFS_FSB_TO_BB(mp, 1), 0, NULL);
1073                if (!bp) {
1074                        xfs_warn(mp, "log device read failed");
1075                        return EIO;
1076                }
1077                xfs_buf_relse(bp);
1078        }
1079        return 0;
1080}
1081
1082/*
1083 * Clear the quotaflags in memory and in the superblock.
1084 */
1085int
1086xfs_mount_reset_sbqflags(
1087        struct xfs_mount        *mp)
1088{
1089        int                     error;
1090        struct xfs_trans        *tp;
1091
1092        mp->m_qflags = 0;
1093
1094        /*
1095         * It is OK to look at sb_qflags here in mount path,
1096         * without m_sb_lock.
1097         */
1098        if (mp->m_sb.sb_qflags == 0)
1099                return 0;
1100        spin_lock(&mp->m_sb_lock);
1101        mp->m_sb.sb_qflags = 0;
1102        spin_unlock(&mp->m_sb_lock);
1103
1104        /*
1105         * If the fs is readonly, let the incore superblock run
1106         * with quotas off but don't flush the update out to disk
1107         */
1108        if (mp->m_flags & XFS_MOUNT_RDONLY)
1109                return 0;
1110
1111        tp = xfs_trans_alloc(mp, XFS_TRANS_QM_SBCHANGE);
1112        error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
1113                                      XFS_DEFAULT_LOG_COUNT);
1114        if (error) {
1115                xfs_trans_cancel(tp, 0);
1116                xfs_alert(mp, "%s: Superblock update failed!", __func__);
1117                return error;
1118        }
1119
1120        xfs_mod_sb(tp, XFS_SB_QFLAGS);
1121        return xfs_trans_commit(tp, 0);
1122}
1123
1124__uint64_t
1125xfs_default_resblks(xfs_mount_t *mp)
1126{
1127        __uint64_t resblks;
1128
1129        /*
1130         * We default to 5% or 8192 fsbs of space reserved, whichever is
1131         * smaller.  This is intended to cover concurrent allocation
1132         * transactions when we initially hit enospc. These each require a 4
1133         * block reservation. Hence by default we cover roughly 2000 concurrent
1134         * allocation reservations.
1135         */
1136        resblks = mp->m_sb.sb_dblocks;
1137        do_div(resblks, 20);
1138        resblks = min_t(__uint64_t, resblks, 8192);
1139        return resblks;
1140}
1141
1142/*
1143 * This function does the following on an initial mount of a file system:
1144 *      - reads the superblock from disk and init the mount struct
1145 *      - if we're a 32-bit kernel, do a size check on the superblock
1146 *              so we don't mount terabyte filesystems
1147 *      - init mount struct realtime fields
1148 *      - allocate inode hash table for fs
1149 *      - init directory manager
1150 *      - perform recovery and init the log manager
1151 */
1152int
1153xfs_mountfs(
1154        xfs_mount_t     *mp)
1155{
1156        xfs_sb_t        *sbp = &(mp->m_sb);
1157        xfs_inode_t     *rip;
1158        __uint64_t      resblks;
1159        uint            quotamount = 0;
1160        uint            quotaflags = 0;
1161        int             error = 0;
1162
1163        xfs_mount_common(mp, sbp);
1164
1165        /*
1166         * Check for a mismatched features2 values.  Older kernels
1167         * read & wrote into the wrong sb offset for sb_features2
1168         * on some platforms due to xfs_sb_t not being 64bit size aligned
1169         * when sb_features2 was added, which made older superblock
1170         * reading/writing routines swap it as a 64-bit value.
1171         *
1172         * For backwards compatibility, we make both slots equal.
1173         *
1174         * If we detect a mismatched field, we OR the set bits into the
1175         * existing features2 field in case it has already been modified; we
1176         * don't want to lose any features.  We then update the bad location
1177         * with the ORed value so that older kernels will see any features2
1178         * flags, and mark the two fields as needing updates once the
1179         * transaction subsystem is online.
1180         */
1181        if (xfs_sb_has_mismatched_features2(sbp)) {
1182                xfs_warn(mp, "correcting sb_features alignment problem");
1183                sbp->sb_features2 |= sbp->sb_bad_features2;
1184                sbp->sb_bad_features2 = sbp->sb_features2;
1185                mp->m_update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
1186
1187                /*
1188                 * Re-check for ATTR2 in case it was found in bad_features2
1189                 * slot.
1190                 */
1191                if (xfs_sb_version_hasattr2(&mp->m_sb) &&
1192                   !(mp->m_flags & XFS_MOUNT_NOATTR2))
1193                        mp->m_flags |= XFS_MOUNT_ATTR2;
1194        }
1195
1196        if (xfs_sb_version_hasattr2(&mp->m_sb) &&
1197           (mp->m_flags & XFS_MOUNT_NOATTR2)) {
1198                xfs_sb_version_removeattr2(&mp->m_sb);
1199                mp->m_update_flags |= XFS_SB_FEATURES2;
1200
1201                /* update sb_versionnum for the clearing of the morebits */
1202                if (!sbp->sb_features2)
1203                        mp->m_update_flags |= XFS_SB_VERSIONNUM;
1204        }
1205
1206        /*
1207         * Check if sb_agblocks is aligned at stripe boundary
1208         * If sb_agblocks is NOT aligned turn off m_dalign since
1209         * allocator alignment is within an ag, therefore ag has
1210         * to be aligned at stripe boundary.
1211         */
1212        error = xfs_update_alignment(mp);
1213        if (error)
1214                goto out;
1215
1216        xfs_alloc_compute_maxlevels(mp);
1217        xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
1218        xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
1219        xfs_ialloc_compute_maxlevels(mp);
1220
1221        xfs_set_maxicount(mp);
1222
1223        error = xfs_uuid_mount(mp);
1224        if (error)
1225                goto out;
1226
1227        /*
1228         * Set the minimum read and write sizes
1229         */
1230        xfs_set_rw_sizes(mp);
1231
1232        /* set the low space thresholds for dynamic preallocation */
1233        xfs_set_low_space_thresholds(mp);
1234
1235        /*
1236         * Set the inode cluster size.
1237         * This may still be overridden by the file system
1238         * block size if it is larger than the chosen cluster size.
1239         */
1240        mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
1241
1242        /*
1243         * Set inode alignment fields
1244         */
1245        xfs_set_inoalignment(mp);
1246
1247        /*
1248         * Check that the data (and log if separate) are an ok size.
1249         */
1250        error = xfs_check_sizes(mp);
1251        if (error)
1252                goto out_remove_uuid;
1253
1254        /*
1255         * Initialize realtime fields in the mount structure
1256         */
1257        error = xfs_rtmount_init(mp);
1258        if (error) {
1259                xfs_warn(mp, "RT mount failed");
1260                goto out_remove_uuid;
1261        }
1262
1263        /*
1264         *  Copies the low order bits of the timestamp and the randomly
1265         *  set "sequence" number out of a UUID.
1266         */
1267        uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);
1268
1269        mp->m_dmevmask = 0;     /* not persistent; set after each mount */
1270
1271        xfs_dir_mount(mp);
1272
1273        /*
1274         * Initialize the attribute manager's entries.
1275         */
1276        mp->m_attr_magicpct = (mp->m_sb.sb_blocksize * 37) / 100;
1277
1278        /*
1279         * Initialize the precomputed transaction reservations values.
1280         */
1281        xfs_trans_init(mp);
1282
1283        /*
1284         * Allocate and initialize the per-ag data.
1285         */
1286        spin_lock_init(&mp->m_perag_lock);
1287        INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
1288        error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
1289        if (error) {
1290                xfs_warn(mp, "Failed per-ag init: %d", error);
1291                goto out_remove_uuid;
1292        }
1293
1294        if (!sbp->sb_logblocks) {
1295                xfs_warn(mp, "no log defined");
1296                XFS_ERROR_REPORT("xfs_mountfs", XFS_ERRLEVEL_LOW, mp);
1297                error = XFS_ERROR(EFSCORRUPTED);
1298                goto out_free_perag;
1299        }
1300
1301        /*
1302         * log's mount-time initialization. Perform 1st part recovery if needed
1303         */
1304        error = xfs_log_mount(mp, mp->m_logdev_targp,
1305                              XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
1306                              XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
1307        if (error) {
1308                xfs_warn(mp, "log mount failed");
1309                goto out_fail_wait;
1310        }
1311
1312        /*
1313         * Now the log is mounted, we know if it was an unclean shutdown or
1314         * not. If it was, with the first phase of recovery has completed, we
1315         * have consistent AG blocks on disk. We have not recovered EFIs yet,
1316         * but they are recovered transactionally in the second recovery phase
1317         * later.
1318         *
1319         * Hence we can safely re-initialise incore superblock counters from
1320         * the per-ag data. These may not be correct if the filesystem was not
1321         * cleanly unmounted, so we need to wait for recovery to finish before
1322         * doing this.
1323         *
1324         * If the filesystem was cleanly unmounted, then we can trust the
1325         * values in the superblock to be correct and we don't need to do
1326         * anything here.
1327         *
1328         * If we are currently making the filesystem, the initialisation will
1329         * fail as the perag data is in an undefined state.
1330         */
1331        if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
1332            !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
1333             !mp->m_sb.sb_inprogress) {
1334                error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
1335                if (error)
1336                        goto out_fail_wait;
1337        }
1338
1339        /*
1340         * Get and sanity-check the root inode.
1341         * Save the pointer to it in the mount structure.
1342         */
1343        error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip);
1344        if (error) {
1345                xfs_warn(mp, "failed to read root inode");
1346                goto out_log_dealloc;
1347        }
1348
1349        ASSERT(rip != NULL);
1350
1351        if (unlikely(!S_ISDIR(rip->i_d.di_mode))) {
1352                xfs_warn(mp, "corrupted root inode %llu: not a directory",
1353                        (unsigned long long)rip->i_ino);
1354                xfs_iunlock(rip, XFS_ILOCK_EXCL);
1355                XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
1356                                 mp);
1357                error = XFS_ERROR(EFSCORRUPTED);
1358                goto out_rele_rip;
1359        }
1360        mp->m_rootip = rip;     /* save it */
1361
1362        xfs_iunlock(rip, XFS_ILOCK_EXCL);
1363
1364        /*
1365         * Initialize realtime inode pointers in the mount structure
1366         */
1367        error = xfs_rtmount_inodes(mp);
1368        if (error) {
1369                /*
1370                 * Free up the root inode.
1371                 */
1372                xfs_warn(mp, "failed to read RT inodes");
1373                goto out_rele_rip;
1374        }
1375
1376        /*
1377         * If this is a read-only mount defer the superblock updates until
1378         * the next remount into writeable mode.  Otherwise we would never
1379         * perform the update e.g. for the root filesystem.
1380         */
1381        if (mp->m_update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
1382                error = xfs_mount_log_sb(mp, mp->m_update_flags);
1383                if (error) {
1384                        xfs_warn(mp, "failed to write sb changes");
1385                        goto out_rtunmount;
1386                }
1387        }
1388
1389        /*
1390         * Initialise the XFS quota management subsystem for this mount
1391         */
1392        if (XFS_IS_QUOTA_RUNNING(mp)) {
1393                error = xfs_qm_newmount(mp, &quotamount, &quotaflags);
1394                if (error)
1395                        goto out_rtunmount;
1396        } else {
1397                ASSERT(!XFS_IS_QUOTA_ON(mp));
1398
1399                /*
1400                 * If a file system had quotas running earlier, but decided to
1401                 * mount without -o uquota/pquota/gquota options, revoke the
1402                 * quotachecked license.
1403                 */
1404                if (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_ACCT) {
1405                        xfs_notice(mp, "resetting quota flags");
1406                        error = xfs_mount_reset_sbqflags(mp);
1407                        if (error)
1408                                return error;
1409                }
1410        }
1411
1412        /*
1413         * Finish recovering the file system.  This part needed to be
1414         * delayed until after the root and real-time bitmap inodes
1415         * were consistently read in.
1416         */
1417        error = xfs_log_mount_finish(mp);
1418        if (error) {
1419                xfs_warn(mp, "log mount finish failed");
1420                goto out_rtunmount;
1421        }
1422
1423        /*
1424         * Complete the quota initialisation, post-log-replay component.
1425         */
1426        if (quotamount) {
1427                ASSERT(mp->m_qflags == 0);
1428                mp->m_qflags = quotaflags;
1429
1430                xfs_qm_mount_quotas(mp);
1431        }
1432
1433        /*
1434         * Now we are mounted, reserve a small amount of unused space for
1435         * privileged transactions. This is needed so that transaction
1436         * space required for critical operations can dip into this pool
1437         * when at ENOSPC. This is needed for operations like create with
1438         * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
1439         * are not allowed to use this reserved space.
1440         *
1441         * This may drive us straight to ENOSPC on mount, but that implies
1442         * we were already there on the last unmount. Warn if this occurs.
1443         */
1444        if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
1445                resblks = xfs_default_resblks(mp);
1446                error = xfs_reserve_blocks(mp, &resblks, NULL);
1447                if (error)
1448                        xfs_warn(mp,
1449        "Unable to allocate reserve blocks. Continuing without reserve pool.");
1450        }
1451
1452        return 0;
1453
1454 out_rtunmount:
1455        xfs_rtunmount_inodes(mp);
1456 out_rele_rip:
1457        IRELE(rip);
1458 out_log_dealloc:
1459        xfs_log_unmount(mp);
1460 out_fail_wait:
1461        if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
1462                xfs_wait_buftarg(mp->m_logdev_targp);
1463        xfs_wait_buftarg(mp->m_ddev_targp);
1464 out_free_perag:
1465        xfs_free_perag(mp);
1466 out_remove_uuid:
1467        xfs_uuid_unmount(mp);
1468 out:
1469        return error;
1470}
1471
1472/*
1473 * This flushes out the inodes,dquots and the superblock, unmounts the
1474 * log and makes sure that incore structures are freed.
1475 */
1476void
1477xfs_unmountfs(
1478        struct xfs_mount        *mp)
1479{
1480        __uint64_t              resblks;
1481        int                     error;
1482
1483        cancel_delayed_work_sync(&mp->m_eofblocks_work);
1484
1485        xfs_qm_unmount_quotas(mp);
1486        xfs_rtunmount_inodes(mp);
1487        IRELE(mp->m_rootip);
1488
1489        /*
1490         * We can potentially deadlock here if we have an inode cluster
1491         * that has been freed has its buffer still pinned in memory because
1492         * the transaction is still sitting in a iclog. The stale inodes
1493         * on that buffer will have their flush locks held until the
1494         * transaction hits the disk and the callbacks run. the inode
1495         * flush takes the flush lock unconditionally and with nothing to
1496         * push out the iclog we will never get that unlocked. hence we
1497         * need to force the log first.
1498         */
1499        xfs_log_force(mp, XFS_LOG_SYNC);
1500
1501        /*
1502         * Flush all pending changes from the AIL.
1503         */
1504        xfs_ail_push_all_sync(mp->m_ail);
1505
1506        /*
1507         * And reclaim all inodes.  At this point there should be no dirty
1508         * inodes and none should be pinned or locked, but use synchronous
1509         * reclaim just to be sure. We can stop background inode reclaim
1510         * here as well if it is still running.
1511         */
1512        cancel_delayed_work_sync(&mp->m_reclaim_work);
1513        xfs_reclaim_inodes(mp, SYNC_WAIT);
1514
1515        xfs_qm_unmount(mp);
1516
1517        /*
1518         * Unreserve any blocks we have so that when we unmount we don't account
1519         * the reserved free space as used. This is really only necessary for
1520         * lazy superblock counting because it trusts the incore superblock
1521         * counters to be absolutely correct on clean unmount.
1522         *
1523         * We don't bother correcting this elsewhere for lazy superblock
1524         * counting because on mount of an unclean filesystem we reconstruct the
1525         * correct counter value and this is irrelevant.
1526         *
1527         * For non-lazy counter filesystems, this doesn't matter at all because
1528         * we only every apply deltas to the superblock and hence the incore
1529         * value does not matter....
1530         */
1531        resblks = 0;
1532        error = xfs_reserve_blocks(mp, &resblks, NULL);
1533        if (error)
1534                xfs_warn(mp, "Unable to free reserved block pool. "
1535                                "Freespace may not be correct on next mount.");
1536
1537        error = xfs_log_sbcount(mp);
1538        if (error)
1539                xfs_warn(mp, "Unable to update superblock counters. "
1540                                "Freespace may not be correct on next mount.");
1541
1542        xfs_log_unmount(mp);
1543        xfs_uuid_unmount(mp);
1544
1545#if defined(DEBUG)
1546        xfs_errortag_clearall(mp, 0);
1547#endif
1548        xfs_free_perag(mp);
1549}
1550
1551int
1552xfs_fs_writable(xfs_mount_t *mp)
1553{
1554        return !(mp->m_super->s_writers.frozen || XFS_FORCED_SHUTDOWN(mp) ||
1555                (mp->m_flags & XFS_MOUNT_RDONLY));
1556}
1557
1558/*
1559 * xfs_log_sbcount
1560 *
1561 * Sync the superblock counters to disk.
1562 *
1563 * Note this code can be called during the process of freezing, so
1564 * we may need to use the transaction allocator which does not
1565 * block when the transaction subsystem is in its frozen state.
1566 */
1567int
1568xfs_log_sbcount(xfs_mount_t *mp)
1569{
1570        xfs_trans_t     *tp;
1571        int             error;
1572
1573        if (!xfs_fs_writable(mp))
1574                return 0;
1575
1576        xfs_icsb_sync_counters(mp, 0);
1577
1578        /*
1579         * we don't need to do this if we are updating the superblock
1580         * counters on every modification.
1581         */
1582        if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
1583                return 0;
1584
1585        tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);
1586        error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
1587                                        XFS_DEFAULT_LOG_COUNT);
1588        if (error) {
1589                xfs_trans_cancel(tp, 0);
1590                return error;
1591        }
1592
1593        xfs_mod_sb(tp, XFS_SB_IFREE | XFS_SB_ICOUNT | XFS_SB_FDBLOCKS);
1594        xfs_trans_set_sync(tp);
1595        error = xfs_trans_commit(tp, 0);
1596        return error;
1597}
1598
1599/*
1600 * xfs_mod_sb() can be used to copy arbitrary changes to the
1601 * in-core superblock into the superblock buffer to be logged.
1602 * It does not provide the higher level of locking that is
1603 * needed to protect the in-core superblock from concurrent
1604 * access.
1605 */
1606void
1607xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
1608{
1609        xfs_buf_t       *bp;
1610        int             first;
1611        int             last;
1612        xfs_mount_t     *mp;
1613        xfs_sb_field_t  f;
1614
1615        ASSERT(fields);
1616        if (!fields)
1617                return;
1618        mp = tp->t_mountp;
1619        bp = xfs_trans_getsb(tp, mp, 0);
1620        first = sizeof(xfs_sb_t);
1621        last = 0;
1622
1623        /* translate/copy */
1624
1625        xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, fields);
1626
1627        /* find modified range */
1628        f = (xfs_sb_field_t)xfs_highbit64((__uint64_t)fields);
1629        ASSERT((1LL << f) & XFS_SB_MOD_BITS);
1630        last = xfs_sb_info[f + 1].offset - 1;
1631
1632        f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
1633        ASSERT((1LL << f) & XFS_SB_MOD_BITS);
1634        first = xfs_sb_info[f].offset;
1635
1636        xfs_trans_log_buf(tp, bp, first, last);
1637}
1638
1639
1640/*
1641 * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply
1642 * a delta to a specified field in the in-core superblock.  Simply
1643 * switch on the field indicated and apply the delta to that field.
1644 * Fields are not allowed to dip below zero, so if the delta would
1645 * do this do not apply it and return EINVAL.
1646 *
1647 * The m_sb_lock must be held when this routine is called.
1648 */
1649STATIC int
1650xfs_mod_incore_sb_unlocked(
1651        xfs_mount_t     *mp,
1652        xfs_sb_field_t  field,
1653        int64_t         delta,
1654        int             rsvd)
1655{
1656        int             scounter;       /* short counter for 32 bit fields */
1657        long long       lcounter;       /* long counter for 64 bit fields */
1658        long long       res_used, rem;
1659
1660        /*
1661         * With the in-core superblock spin lock held, switch
1662         * on the indicated field.  Apply the delta to the
1663         * proper field.  If the fields value would dip below
1664         * 0, then do not apply the delta and return EINVAL.
1665         */
1666        switch (field) {
1667        case XFS_SBS_ICOUNT:
1668                lcounter = (long long)mp->m_sb.sb_icount;
1669                lcounter += delta;
1670                if (lcounter < 0) {
1671                        ASSERT(0);
1672                        return XFS_ERROR(EINVAL);
1673                }
1674                mp->m_sb.sb_icount = lcounter;
1675                return 0;
1676        case XFS_SBS_IFREE:
1677                lcounter = (long long)mp->m_sb.sb_ifree;
1678                lcounter += delta;
1679                if (lcounter < 0) {
1680                        ASSERT(0);
1681                        return XFS_ERROR(EINVAL);
1682                }
1683                mp->m_sb.sb_ifree = lcounter;
1684                return 0;
1685        case XFS_SBS_FDBLOCKS:
1686                lcounter = (long long)
1687                        mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
1688                res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
1689
1690                if (delta > 0) {                /* Putting blocks back */
1691                        if (res_used > delta) {
1692                                mp->m_resblks_avail += delta;
1693                        } else {
1694                                rem = delta - res_used;
1695                                mp->m_resblks_avail = mp->m_resblks;
1696                                lcounter += rem;
1697                        }
1698                } else {                                /* Taking blocks away */
1699                        lcounter += delta;
1700                        if (lcounter >= 0) {
1701                                mp->m_sb.sb_fdblocks = lcounter +
1702                                                        XFS_ALLOC_SET_ASIDE(mp);
1703                                return 0;
1704                        }
1705
1706                        /*
1707                         * We are out of blocks, use any available reserved
1708                         * blocks if were allowed to.
1709                         */
1710                        if (!rsvd)
1711                                return XFS_ERROR(ENOSPC);
1712
1713                        lcounter = (long long)mp->m_resblks_avail + delta;
1714                        if (lcounter >= 0) {
1715                                mp->m_resblks_avail = lcounter;
1716                                return 0;
1717                        }
1718                        printk_once(KERN_WARNING
1719                                "Filesystem \"%s\": reserve blocks depleted! "
1720                                "Consider increasing reserve pool size.",
1721                                mp->m_fsname);
1722                        return XFS_ERROR(ENOSPC);
1723                }
1724
1725                mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
1726                return 0;
1727        case XFS_SBS_FREXTENTS:
1728                lcounter = (long long)mp->m_sb.sb_frextents;
1729                lcounter += delta;
1730                if (lcounter < 0) {
1731                        return XFS_ERROR(ENOSPC);
1732                }
1733                mp->m_sb.sb_frextents = lcounter;
1734                return 0;
1735        case XFS_SBS_DBLOCKS:
1736                lcounter = (long long)mp->m_sb.sb_dblocks;
1737                lcounter += delta;
1738                if (lcounter < 0) {
1739                        ASSERT(0);
1740                        return XFS_ERROR(EINVAL);
1741                }
1742                mp->m_sb.sb_dblocks = lcounter;
1743                return 0;
1744        case XFS_SBS_AGCOUNT:
1745                scounter = mp->m_sb.sb_agcount;
1746                scounter += delta;
1747                if (scounter < 0) {
1748                        ASSERT(0);
1749                        return XFS_ERROR(EINVAL);
1750                }
1751                mp->m_sb.sb_agcount = scounter;
1752                return 0;
1753        case XFS_SBS_IMAX_PCT:
1754                scounter = mp->m_sb.sb_imax_pct;
1755                scounter += delta;
1756                if (scounter < 0) {
1757                        ASSERT(0);
1758                        return XFS_ERROR(EINVAL);
1759                }
1760                mp->m_sb.sb_imax_pct = scounter;
1761                return 0;
1762        case XFS_SBS_REXTSIZE:
1763                scounter = mp->m_sb.sb_rextsize;
1764                scounter += delta;
1765                if (scounter < 0) {
1766                        ASSERT(0);
1767                        return XFS_ERROR(EINVAL);
1768                }
1769                mp->m_sb.sb_rextsize = scounter;
1770                return 0;
1771        case XFS_SBS_RBMBLOCKS:
1772                scounter = mp->m_sb.sb_rbmblocks;
1773                scounter += delta;
1774                if (scounter < 0) {
1775                        ASSERT(0);
1776                        return XFS_ERROR(EINVAL);
1777                }
1778                mp->m_sb.sb_rbmblocks = scounter;
1779                return 0;
1780        case XFS_SBS_RBLOCKS:
1781                lcounter = (long long)mp->m_sb.sb_rblocks;
1782                lcounter += delta;
1783                if (lcounter < 0) {
1784                        ASSERT(0);
1785                        return XFS_ERROR(EINVAL);
1786                }
1787                mp->m_sb.sb_rblocks = lcounter;
1788                return 0;
1789        case XFS_SBS_REXTENTS:
1790                lcounter = (long long)mp->m_sb.sb_rextents;
1791                lcounter += delta;
1792                if (lcounter < 0) {
1793                        ASSERT(0);
1794                        return XFS_ERROR(EINVAL);
1795                }
1796                mp->m_sb.sb_rextents = lcounter;
1797                return 0;
1798        case XFS_SBS_REXTSLOG:
1799                scounter = mp->m_sb.sb_rextslog;
1800                scounter += delta;
1801                if (scounter < 0) {
1802                        ASSERT(0);
1803                        return XFS_ERROR(EINVAL);
1804                }
1805                mp->m_sb.sb_rextslog = scounter;
1806                return 0;
1807        default:
1808                ASSERT(0);
1809                return XFS_ERROR(EINVAL);
1810        }
1811}
1812
1813/*
1814 * xfs_mod_incore_sb() is used to change a field in the in-core
1815 * superblock structure by the specified delta.  This modification
1816 * is protected by the m_sb_lock.  Just use the xfs_mod_incore_sb_unlocked()
1817 * routine to do the work.
1818 */
1819int
1820xfs_mod_incore_sb(
1821        struct xfs_mount        *mp,
1822        xfs_sb_field_t          field,
1823        int64_t                 delta,
1824        int                     rsvd)
1825{
1826        int                     status;
1827
1828#ifdef HAVE_PERCPU_SB
1829        ASSERT(field < XFS_SBS_ICOUNT || field > XFS_SBS_FDBLOCKS);
1830#endif
1831        spin_lock(&mp->m_sb_lock);
1832        status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
1833        spin_unlock(&mp->m_sb_lock);
1834
1835        return status;
1836}
1837
1838/*
1839 * Change more than one field in the in-core superblock structure at a time.
1840 *
1841 * The fields and changes to those fields are specified in the array of
1842 * xfs_mod_sb structures passed in.  Either all of the specified deltas
1843 * will be applied or none of them will.  If any modified field dips below 0,
1844 * then all modifications will be backed out and EINVAL will be returned.
1845 *
1846 * Note that this function may not be used for the superblock values that
1847 * are tracked with the in-memory per-cpu counters - a direct call to
1848 * xfs_icsb_modify_counters is required for these.
1849 */
1850int
1851xfs_mod_incore_sb_batch(
1852        struct xfs_mount        *mp,
1853        xfs_mod_sb_t            *msb,
1854        uint                    nmsb,
1855        int                     rsvd)
1856{
1857        xfs_mod_sb_t            *msbp;
1858        int                     error = 0;
1859
1860        /*
1861         * Loop through the array of mod structures and apply each individually.
1862         * If any fail, then back out all those which have already been applied.
1863         * Do all of this within the scope of the m_sb_lock so that all of the
1864         * changes will be atomic.
1865         */
1866        spin_lock(&mp->m_sb_lock);
1867        for (msbp = msb; msbp < (msb + nmsb); msbp++) {
1868                ASSERT(msbp->msb_field < XFS_SBS_ICOUNT ||
1869                       msbp->msb_field > XFS_SBS_FDBLOCKS);
1870
1871                error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
1872                                                   msbp->msb_delta, rsvd);
1873                if (error)
1874                        goto unwind;
1875        }
1876        spin_unlock(&mp->m_sb_lock);
1877        return 0;
1878
1879unwind:
1880        while (--msbp >= msb) {
1881                error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
1882                                                   -msbp->msb_delta, rsvd);
1883                ASSERT(error == 0);
1884        }
1885        spin_unlock(&mp->m_sb_lock);
1886        return error;
1887}
1888
1889/*
1890 * xfs_getsb() is called to obtain the buffer for the superblock.
1891 * The buffer is returned locked and read in from disk.
1892 * The buffer should be released with a call to xfs_brelse().
1893 *
1894 * If the flags parameter is BUF_TRYLOCK, then we'll only return
1895 * the superblock buffer if it can be locked without sleeping.
1896 * If it can't then we'll return NULL.
1897 */
1898struct xfs_buf *
1899xfs_getsb(
1900        struct xfs_mount        *mp,
1901        int                     flags)
1902{
1903        struct xfs_buf          *bp = mp->m_sb_bp;
1904
1905        if (!xfs_buf_trylock(bp)) {
1906                if (flags & XBF_TRYLOCK)
1907                        return NULL;
1908                xfs_buf_lock(bp);
1909        }
1910
1911        xfs_buf_hold(bp);
1912        ASSERT(XFS_BUF_ISDONE(bp));
1913        return bp;
1914}
1915
1916/*
1917 * Used to free the superblock along various error paths.
1918 */
1919void
1920xfs_freesb(
1921        struct xfs_mount        *mp)
1922{
1923        struct xfs_buf          *bp = mp->m_sb_bp;
1924
1925        xfs_buf_lock(bp);
1926        mp->m_sb_bp = NULL;
1927        xfs_buf_relse(bp);
1928}
1929
1930/*
1931 * Used to log changes to the superblock unit and width fields which could
1932 * be altered by the mount options, as well as any potential sb_features2
1933 * fixup. Only the first superblock is updated.
1934 */
1935int
1936xfs_mount_log_sb(
1937        xfs_mount_t     *mp,
1938        __int64_t       fields)
1939{
1940        xfs_trans_t     *tp;
1941        int             error;
1942
1943        ASSERT(fields & (XFS_SB_UNIT | XFS_SB_WIDTH | XFS_SB_UUID |
1944                         XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2 |
1945                         XFS_SB_VERSIONNUM));
1946
1947        tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);
1948        error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
1949                                XFS_DEFAULT_LOG_COUNT);
1950        if (error) {
1951                xfs_trans_cancel(tp, 0);
1952                return error;
1953        }
1954        xfs_mod_sb(tp, fields);
1955        error = xfs_trans_commit(tp, 0);
1956        return error;
1957}
1958
1959/*
1960 * If the underlying (data/log/rt) device is readonly, there are some
1961 * operations that cannot proceed.
1962 */
1963int
1964xfs_dev_is_read_only(
1965        struct xfs_mount        *mp,
1966        char                    *message)
1967{
1968        if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
1969            xfs_readonly_buftarg(mp->m_logdev_targp) ||
1970            (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
1971                xfs_notice(mp, "%s required on read-only device.", message);
1972                xfs_notice(mp, "write access unavailable, cannot proceed.");
1973                return EROFS;
1974        }
1975        return 0;
1976}
1977
1978#ifdef HAVE_PERCPU_SB
1979/*
1980 * Per-cpu incore superblock counters
1981 *
1982 * Simple concept, difficult implementation
1983 *
1984 * Basically, replace the incore superblock counters with a distributed per cpu
1985 * counter for contended fields (e.g.  free block count).
1986 *
1987 * Difficulties arise in that the incore sb is used for ENOSPC checking, and
1988 * hence needs to be accurately read when we are running low on space. Hence
1989 * there is a method to enable and disable the per-cpu counters based on how
1990 * much "stuff" is available in them.
1991 *
1992 * Basically, a counter is enabled if there is enough free resource to justify
1993 * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local
1994 * ENOSPC), then we disable the counters to synchronise all callers and
1995 * re-distribute the available resources.
1996 *
1997 * If, once we redistributed the available resources, we still get a failure,
1998 * we disable the per-cpu counter and go through the slow path.
1999 *
2000 * The slow path is the current xfs_mod_incore_sb() function.  This means that
2001 * when we disable a per-cpu counter, we need to drain its resources back to
2002 * the global superblock. We do this after disabling the counter to prevent
2003 * more threads from queueing up on the counter.
2004 *
2005 * Essentially, this means that we still need a lock in the fast path to enable
2006 * synchronisation between the global counters and the per-cpu counters. This
2007 * is not a problem because the lock will be local to a CPU almost all the time
2008 * and have little contention except when we get to ENOSPC conditions.
2009 *
2010 * Basically, this lock becomes a barrier that enables us to lock out the fast
2011 * path while we do things like enabling and disabling counters and
2012 * synchronising the counters.
2013 *
2014 * Locking rules:
2015 *
2016 *      1. m_sb_lock before picking up per-cpu locks
2017 *      2. per-cpu locks always picked up via for_each_online_cpu() order
2018 *      3. accurate counter sync requires m_sb_lock + per cpu locks
2019 *      4. modifying per-cpu counters requires holding per-cpu lock
2020 *      5. modifying global counters requires holding m_sb_lock
2021 *      6. enabling or disabling a counter requires holding the m_sb_lock 
2022 *         and _none_ of the per-cpu locks.
2023 *
2024 * Disabled counters are only ever re-enabled by a balance operation
2025 * that results in more free resources per CPU than a given threshold.
2026 * To ensure counters don't remain disabled, they are rebalanced when
2027 * the global resource goes above a higher threshold (i.e. some hysteresis
2028 * is present to prevent thrashing).
2029 */
2030
2031#ifdef CONFIG_HOTPLUG_CPU
2032/*
2033 * hot-plug CPU notifier support.
2034 *
2035 * We need a notifier per filesystem as we need to be able to identify
2036 * the filesystem to balance the counters out. This is achieved by
2037 * having a notifier block embedded in the xfs_mount_t and doing pointer
2038 * magic to get the mount pointer from the notifier block address.
2039 */
2040STATIC int
2041xfs_icsb_cpu_notify(
2042        struct notifier_block *nfb,
2043        unsigned long action,
2044        void *hcpu)
2045{
2046        xfs_icsb_cnts_t *cntp;
2047        xfs_mount_t     *mp;
2048
2049        mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
2050        cntp = (xfs_icsb_cnts_t *)
2051                        per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
2052        switch (action) {
2053        case CPU_UP_PREPARE:
2054        case CPU_UP_PREPARE_FROZEN:
2055                /* Easy Case - initialize the area and locks, and
2056                 * then rebalance when online does everything else for us. */
2057                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
2058                break;
2059        case CPU_ONLINE:
2060        case CPU_ONLINE_FROZEN:
2061                xfs_icsb_lock(mp);
2062                xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
2063                xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
2064                xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
2065                xfs_icsb_unlock(mp);
2066                break;
2067        case CPU_DEAD:
2068        case CPU_DEAD_FROZEN:
2069                /* Disable all the counters, then fold the dead cpu's
2070                 * count into the total on the global superblock and
2071                 * re-enable the counters. */
2072                xfs_icsb_lock(mp);
2073                spin_lock(&mp->m_sb_lock);
2074                xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
2075                xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
2076                xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
2077
2078                mp->m_sb.sb_icount += cntp->icsb_icount;
2079                mp->m_sb.sb_ifree += cntp->icsb_ifree;
2080                mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
2081
2082                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
2083
2084                xfs_icsb_balance_counter_locked(mp, XFS_SBS_ICOUNT, 0);
2085                xfs_icsb_balance_counter_locked(mp, XFS_SBS_IFREE, 0);
2086                xfs_icsb_balance_counter_locked(mp, XFS_SBS_FDBLOCKS, 0);
2087                spin_unlock(&mp->m_sb_lock);
2088                xfs_icsb_unlock(mp);
2089                break;
2090        }
2091
2092        return NOTIFY_OK;
2093}
2094#endif /* CONFIG_HOTPLUG_CPU */
2095
2096int
2097xfs_icsb_init_counters(
2098        xfs_mount_t     *mp)
2099{
2100        xfs_icsb_cnts_t *cntp;
2101        int             i;
2102
2103        mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
2104        if (mp->m_sb_cnts == NULL)
2105                return -ENOMEM;
2106
2107#ifdef CONFIG_HOTPLUG_CPU
2108        mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
2109        mp->m_icsb_notifier.priority = 0;
2110        register_hotcpu_notifier(&mp->m_icsb_notifier);
2111#endif /* CONFIG_HOTPLUG_CPU */
2112
2113        for_each_online_cpu(i) {
2114                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2115                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
2116        }
2117
2118        mutex_init(&mp->m_icsb_mutex);
2119
2120        /*
2121         * start with all counters disabled so that the
2122         * initial balance kicks us off correctly
2123         */
2124        mp->m_icsb_counters = -1;
2125        return 0;
2126}
2127
2128void
2129xfs_icsb_reinit_counters(
2130        xfs_mount_t     *mp)
2131{
2132        xfs_icsb_lock(mp);
2133        /*
2134         * start with all counters disabled so that the
2135         * initial balance kicks us off correctly
2136         */
2137        mp->m_icsb_counters = -1;
2138        xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
2139        xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
2140        xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
2141        xfs_icsb_unlock(mp);
2142}
2143
2144void
2145xfs_icsb_destroy_counters(
2146        xfs_mount_t     *mp)
2147{
2148        if (mp->m_sb_cnts) {
2149                unregister_hotcpu_notifier(&mp->m_icsb_notifier);
2150                free_percpu(mp->m_sb_cnts);
2151        }
2152        mutex_destroy(&mp->m_icsb_mutex);
2153}
2154
2155STATIC void
2156xfs_icsb_lock_cntr(
2157        xfs_icsb_cnts_t *icsbp)
2158{
2159        while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) {
2160                ndelay(1000);
2161        }
2162}
2163
2164STATIC void
2165xfs_icsb_unlock_cntr(
2166        xfs_icsb_cnts_t *icsbp)
2167{
2168        clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
2169}
2170
2171
2172STATIC void
2173xfs_icsb_lock_all_counters(
2174        xfs_mount_t     *mp)
2175{
2176        xfs_icsb_cnts_t *cntp;
2177        int             i;
2178
2179        for_each_online_cpu(i) {
2180                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2181                xfs_icsb_lock_cntr(cntp);
2182        }
2183}
2184
2185STATIC void
2186xfs_icsb_unlock_all_counters(
2187        xfs_mount_t     *mp)
2188{
2189        xfs_icsb_cnts_t *cntp;
2190        int             i;
2191
2192        for_each_online_cpu(i) {
2193                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2194                xfs_icsb_unlock_cntr(cntp);
2195        }
2196}
2197
2198STATIC void
2199xfs_icsb_count(
2200        xfs_mount_t     *mp,
2201        xfs_icsb_cnts_t *cnt,
2202        int             flags)
2203{
2204        xfs_icsb_cnts_t *cntp;
2205        int             i;
2206
2207        memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
2208
2209        if (!(flags & XFS_ICSB_LAZY_COUNT))
2210                xfs_icsb_lock_all_counters(mp);
2211
2212        for_each_online_cpu(i) {
2213                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
2214                cnt->icsb_icount += cntp->icsb_icount;
2215                cnt->icsb_ifree += cntp->icsb_ifree;
2216                cnt->icsb_fdblocks += cntp->icsb_fdblocks;
2217        }
2218
2219        if (!(flags & XFS_ICSB_LAZY_COUNT))
2220                xfs_icsb_unlock_all_counters(mp);
2221}
2222
2223STATIC int
2224xfs_icsb_counter_disabled(
2225        xfs_mount_t     *mp,
2226        xfs_sb_field_t  field)
2227{
2228        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
2229        return test_bit(field, &mp->m_icsb_counters);
2230}
2231
2232STATIC void
2233xfs_icsb_disable_counter(
2234        xfs_mount_t     *mp,
2235        xfs_sb_field_t  field)
2236{
2237        xfs_icsb_cnts_t cnt;
2238
2239        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
2240
2241        /*
2242         * If we are already disabled, then there is nothing to do
2243         * here. We check before locking all the counters to avoid
2244         * the expensive lock operation when being called in the
2245         * slow path and the counter is already disabled. This is
2246         * safe because the only time we set or clear this state is under
2247         * the m_icsb_mutex.
2248         */
2249        if (xfs_icsb_counter_disabled(mp, field))
2250                return;
2251
2252        xfs_icsb_lock_all_counters(mp);
2253        if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
2254                /* drain back to superblock */
2255
2256                xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT);
2257                switch(field) {
2258                case XFS_SBS_ICOUNT:
2259                        mp->m_sb.sb_icount = cnt.icsb_icount;
2260                        break;
2261                case XFS_SBS_IFREE:
2262                        mp->m_sb.sb_ifree = cnt.icsb_ifree;
2263                        break;
2264                case XFS_SBS_FDBLOCKS:
2265                        mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
2266                        break;
2267                default:
2268                        BUG();
2269                }
2270        }
2271
2272        xfs_icsb_unlock_all_counters(mp);
2273}
2274
2275STATIC void
2276xfs_icsb_enable_counter(
2277        xfs_mount_t     *mp,
2278        xfs_sb_field_t  field,
2279        uint64_t        count,
2280        uint64_t        resid)
2281{
2282        xfs_icsb_cnts_t *cntp;
2283        int             i;
2284
2285        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
2286
2287        xfs_icsb_lock_all_counters(mp);
2288        for_each_online_cpu(i) {
2289                cntp = per_cpu_ptr(mp->m_sb_cnts, i);
2290                switch (field) {
2291                case XFS_SBS_ICOUNT:
2292                        cntp->icsb_icount = count + resid;
2293                        break;
2294                case XFS_SBS_IFREE:
2295                        cntp->icsb_ifree = count + resid;
2296                        break;
2297                case XFS_SBS_FDBLOCKS:
2298                        cntp->icsb_fdblocks = count + resid;
2299                        break;
2300                default:
2301                        BUG();
2302                        break;
2303                }
2304                resid = 0;
2305        }
2306        clear_bit(field, &mp->m_icsb_counters);
2307        xfs_icsb_unlock_all_counters(mp);
2308}
2309
2310void
2311xfs_icsb_sync_counters_locked(
2312        xfs_mount_t     *mp,
2313        int             flags)
2314{
2315        xfs_icsb_cnts_t cnt;
2316
2317        xfs_icsb_count(mp, &cnt, flags);
2318
2319        if (!xfs_icsb_counter_disabled(mp, XFS_SBS_ICOUNT))
2320                mp->m_sb.sb_icount = cnt.icsb_icount;
2321        if (!xfs_icsb_counter_disabled(mp, XFS_SBS_IFREE))
2322                mp->m_sb.sb_ifree = cnt.icsb_ifree;
2323        if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
2324                mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
2325}
2326
2327/*
2328 * Accurate update of per-cpu counters to incore superblock
2329 */
2330void
2331xfs_icsb_sync_counters(
2332        xfs_mount_t     *mp,
2333        int             flags)
2334{
2335        spin_lock(&mp->m_sb_lock);
2336        xfs_icsb_sync_counters_locked(mp, flags);
2337        spin_unlock(&mp->m_sb_lock);
2338}
2339
2340/*
2341 * Balance and enable/disable counters as necessary.
2342 *
2343 * Thresholds for re-enabling counters are somewhat magic.  inode counts are
2344 * chosen to be the same number as single on disk allocation chunk per CPU, and
2345 * free blocks is something far enough zero that we aren't going thrash when we
2346 * get near ENOSPC. We also need to supply a minimum we require per cpu to
2347 * prevent looping endlessly when xfs_alloc_space asks for more than will
2348 * be distributed to a single CPU but each CPU has enough blocks to be
2349 * reenabled.
2350 *
2351 * Note that we can be called when counters are already disabled.
2352 * xfs_icsb_disable_counter() optimises the counter locking in this case to
2353 * prevent locking every per-cpu counter needlessly.
2354 */
2355
2356#define XFS_ICSB_INO_CNTR_REENABLE      (uint64_t)64
2357#define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \
2358                (uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp))
2359STATIC void
2360xfs_icsb_balance_counter_locked(
2361        xfs_mount_t     *mp,
2362        xfs_sb_field_t  field,
2363        int             min_per_cpu)
2364{
2365        uint64_t        count, resid;
2366        int             weight = num_online_cpus();
2367        uint64_t        min = (uint64_t)min_per_cpu;
2368
2369        /* disable counter and sync counter */
2370        xfs_icsb_disable_counter(mp, field);
2371
2372        /* update counters  - first CPU gets residual*/
2373        switch (field) {
2374        case XFS_SBS_ICOUNT:
2375                count = mp->m_sb.sb_icount;
2376                resid = do_div(count, weight);
2377                if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
2378                        return;
2379                break;
2380        case XFS_SBS_IFREE:
2381                count = mp->m_sb.sb_ifree;
2382                resid = do_div(count, weight);
2383                if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
2384                        return;
2385                break;
2386        case XFS_SBS_FDBLOCKS:
2387                count = mp->m_sb.sb_fdblocks;
2388                resid = do_div(count, weight);
2389                if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp)))
2390                        return;
2391                break;
2392        default:
2393                BUG();
2394                count = resid = 0;      /* quiet, gcc */
2395                break;
2396        }
2397
2398        xfs_icsb_enable_counter(mp, field, count, resid);
2399}
2400
2401STATIC void
2402xfs_icsb_balance_counter(
2403        xfs_mount_t     *mp,
2404        xfs_sb_field_t  fields,
2405        int             min_per_cpu)
2406{
2407        spin_lock(&mp->m_sb_lock);
2408        xfs_icsb_balance_counter_locked(mp, fields, min_per_cpu);
2409        spin_unlock(&mp->m_sb_lock);
2410}
2411
2412int
2413xfs_icsb_modify_counters(
2414        xfs_mount_t     *mp,
2415        xfs_sb_field_t  field,
2416        int64_t         delta,
2417        int             rsvd)
2418{
2419        xfs_icsb_cnts_t *icsbp;
2420        long long       lcounter;       /* long counter for 64 bit fields */
2421        int             ret = 0;
2422
2423        might_sleep();
2424again:
2425        preempt_disable();
2426        icsbp = this_cpu_ptr(mp->m_sb_cnts);
2427
2428        /*
2429         * if the counter is disabled, go to slow path
2430         */
2431        if (unlikely(xfs_icsb_counter_disabled(mp, field)))
2432                goto slow_path;
2433        xfs_icsb_lock_cntr(icsbp);
2434        if (unlikely(xfs_icsb_counter_disabled(mp, field))) {
2435                xfs_icsb_unlock_cntr(icsbp);
2436                goto slow_path;
2437        }
2438
2439        switch (field) {
2440        case XFS_SBS_ICOUNT:
2441                lcounter = icsbp->icsb_icount;
2442                lcounter += delta;
2443                if (unlikely(lcounter < 0))
2444                        goto balance_counter;
2445                icsbp->icsb_icount = lcounter;
2446                break;
2447
2448        case XFS_SBS_IFREE:
2449                lcounter = icsbp->icsb_ifree;
2450                lcounter += delta;
2451                if (unlikely(lcounter < 0))
2452                        goto balance_counter;
2453                icsbp->icsb_ifree = lcounter;
2454                break;
2455
2456        case XFS_SBS_FDBLOCKS:
2457                BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
2458
2459                lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
2460                lcounter += delta;
2461                if (unlikely(lcounter < 0))
2462                        goto balance_counter;
2463                icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
2464                break;
2465        default:
2466                BUG();
2467                break;
2468        }
2469        xfs_icsb_unlock_cntr(icsbp);
2470        preempt_enable();
2471        return 0;
2472
2473slow_path:
2474        preempt_enable();
2475
2476        /*
2477         * serialise with a mutex so we don't burn lots of cpu on
2478         * the superblock lock. We still need to hold the superblock
2479         * lock, however, when we modify the global structures.
2480         */
2481        xfs_icsb_lock(mp);
2482
2483        /*
2484         * Now running atomically.
2485         *
2486         * If the counter is enabled, someone has beaten us to rebalancing.
2487         * Drop the lock and try again in the fast path....
2488         */
2489        if (!(xfs_icsb_counter_disabled(mp, field))) {
2490                xfs_icsb_unlock(mp);
2491                goto again;
2492        }
2493
2494        /*
2495         * The counter is currently disabled. Because we are
2496         * running atomically here, we know a rebalance cannot
2497         * be in progress. Hence we can go straight to operating
2498         * on the global superblock. We do not call xfs_mod_incore_sb()
2499         * here even though we need to get the m_sb_lock. Doing so
2500         * will cause us to re-enter this function and deadlock.
2501         * Hence we get the m_sb_lock ourselves and then call
2502         * xfs_mod_incore_sb_unlocked() as the unlocked path operates
2503         * directly on the global counters.
2504         */
2505        spin_lock(&mp->m_sb_lock);
2506        ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
2507        spin_unlock(&mp->m_sb_lock);
2508
2509        /*
2510         * Now that we've modified the global superblock, we
2511         * may be able to re-enable the distributed counters
2512         * (e.g. lots of space just got freed). After that
2513         * we are done.
2514         */
2515        if (ret != ENOSPC)
2516                xfs_icsb_balance_counter(mp, field, 0);
2517        xfs_icsb_unlock(mp);
2518        return ret;
2519
2520balance_counter:
2521        xfs_icsb_unlock_cntr(icsbp);
2522        preempt_enable();
2523
2524        /*
2525         * We may have multiple threads here if multiple per-cpu
2526         * counters run dry at the same time. This will mean we can
2527         * do more balances than strictly necessary but it is not
2528         * the common slowpath case.
2529         */
2530        xfs_icsb_lock(mp);
2531
2532        /*
2533         * running atomically.
2534         *
2535         * This will leave the counter in the correct state for future
2536         * accesses. After the rebalance, we simply try again and our retry
2537         * will either succeed through the fast path or slow path without
2538         * another balance operation being required.
2539         */
2540        xfs_icsb_balance_counter(mp, field, delta);
2541        xfs_icsb_unlock(mp);
2542        goto again;
2543}
2544
2545#endif
2546
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