fs/xfs/xfs_fsops.c

   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_inum.h"
  23 #include "xfs_log.h"
  24 #include "xfs_trans.h"
  25 #include "xfs_sb.h"
  26 #include "xfs_ag.h"
  27 #include "xfs_mount.h"
  28 #include "xfs_bmap_btree.h"
  29 #include "xfs_alloc_btree.h"
  30 #include "xfs_ialloc_btree.h"
  31 #include "xfs_dinode.h"
  32 #include "xfs_inode.h"
  33 #include "xfs_inode_item.h"
  34 #include "xfs_btree.h"
  35 #include "xfs_error.h"
  36 #include "xfs_alloc.h"
  37 #include "xfs_ialloc.h"
  38 #include "xfs_fsops.h"
  39 #include "xfs_itable.h"
  40 #include "xfs_trans_space.h"
  41 #include "xfs_rtalloc.h"
  42 #include "xfs_rw.h"
  43 #include "xfs_filestream.h"
  44 #include "xfs_trace.h"
  45
  46 /*
  47  * File system operations
  48  */
  49
  50 int
  51 xfs_fs_geometry(
  52         xfs_mount_t             *mp,
  53         xfs_fsop_geom_t         *geo,
  54         int                     new_version)
  55 {
  56
  57         memset(geo, 0, sizeof(*geo));
  58
  59         geo->blocksize = mp->m_sb.sb_blocksize;
  60         geo->rtextsize = mp->m_sb.sb_rextsize;
  61         geo->agblocks = mp->m_sb.sb_agblocks;
  62         geo->agcount = mp->m_sb.sb_agcount;
  63         geo->logblocks = mp->m_sb.sb_logblocks;
  64         geo->sectsize = mp->m_sb.sb_sectsize;
  65         geo->inodesize = mp->m_sb.sb_inodesize;
  66         geo->imaxpct = mp->m_sb.sb_imax_pct;
  67         geo->datablocks = mp->m_sb.sb_dblocks;
  68         geo->rtblocks = mp->m_sb.sb_rblocks;
  69         geo->rtextents = mp->m_sb.sb_rextents;
  70         geo->logstart = mp->m_sb.sb_logstart;
  71         ASSERT(sizeof(geo->uuid)==sizeof(mp->m_sb.sb_uuid));
  72         memcpy(geo->uuid, &mp->m_sb.sb_uuid, sizeof(mp->m_sb.sb_uuid));
  73         if (new_version >= 2) {
  74                 geo->sunit = mp->m_sb.sb_unit;
  75                 geo->swidth = mp->m_sb.sb_width;
  76         }
  77         if (new_version >= 3) {
  78                 geo->version = XFS_FSOP_GEOM_VERSION;
  79                 geo->flags =
  80                         (xfs_sb_version_hasattr(&mp->m_sb) ?
  81                                 XFS_FSOP_GEOM_FLAGS_ATTR : 0) |
  82                         (xfs_sb_version_hasnlink(&mp->m_sb) ?
  83                                 XFS_FSOP_GEOM_FLAGS_NLINK : 0) |
  84                         (xfs_sb_version_hasquota(&mp->m_sb) ?
  85                                 XFS_FSOP_GEOM_FLAGS_QUOTA : 0) |
  86                         (xfs_sb_version_hasalign(&mp->m_sb) ?
  87                                 XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
  88                         (xfs_sb_version_hasdalign(&mp->m_sb) ?
  89                                 XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
  90                         (xfs_sb_version_hasshared(&mp->m_sb) ?
  91                                 XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
  92                         (xfs_sb_version_hasextflgbit(&mp->m_sb) ?
  93                                 XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
  94                         (xfs_sb_version_hasdirv2(&mp->m_sb) ?
  95                                 XFS_FSOP_GEOM_FLAGS_DIRV2 : 0) |
  96                         (xfs_sb_version_hassector(&mp->m_sb) ?
  97                                 XFS_FSOP_GEOM_FLAGS_SECTOR : 0) |
  98                         (xfs_sb_version_hasasciici(&mp->m_sb) ?
  99                                 XFS_FSOP_GEOM_FLAGS_DIRV2CI : 0) |
 100                         (xfs_sb_version_haslazysbcount(&mp->m_sb) ?
 101                                 XFS_FSOP_GEOM_FLAGS_LAZYSB : 0) |
 102                         (xfs_sb_version_hasattr2(&mp->m_sb) ?
 103                                 XFS_FSOP_GEOM_FLAGS_ATTR2 : 0);
 104                 geo->logsectsize = xfs_sb_version_hassector(&mp->m_sb) ?
 105                                 mp->m_sb.sb_logsectsize : BBSIZE;
 106                 geo->rtsectsize = mp->m_sb.sb_blocksize;
 107                 geo->dirblocksize = mp->m_dirblksize;
 108         }
 109         if (new_version >= 4) {
 110                 geo->flags |=
 111                         (xfs_sb_version_haslogv2(&mp->m_sb) ?
 112                                 XFS_FSOP_GEOM_FLAGS_LOGV2 : 0);
 113                 geo->logsunit = mp->m_sb.sb_logsunit;
 114         }
 115         return 0;
 116 }
 117
 118 static int
 119 xfs_growfs_data_private(
 120         xfs_mount_t             *mp,            /* mount point for filesystem */
 121         xfs_growfs_data_t       *in)            /* growfs data input struct */
 122 {
 123         xfs_agf_t               *agf;
 124         xfs_agi_t               *agi;
 125         xfs_agnumber_t          agno;
 126         xfs_extlen_t            agsize;
 127         xfs_extlen_t            tmpsize;
 128         xfs_alloc_rec_t         *arec;
 129         struct xfs_btree_block  *block;
 130         xfs_buf_t               *bp;
 131         int                     bucket;
 132         int                     dpct;
 133         int                     error;
 134         xfs_agnumber_t          nagcount;
 135         xfs_agnumber_t          nagimax = 0;
 136         xfs_rfsblock_t          nb, nb_mod;
 137         xfs_rfsblock_t          new;
 138         xfs_rfsblock_t          nfree;
 139         xfs_agnumber_t          oagcount;
 140         int                     pct;
 141         xfs_trans_t             *tp;
 142
 143         nb = in->newblocks;
 144         pct = in->imaxpct;
 145         if (nb < mp->m_sb.sb_dblocks || pct < 0 || pct > 100)
 146                 return XFS_ERROR(EINVAL);
 147         if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
 148                 return error;
 149         dpct = pct - mp->m_sb.sb_imax_pct;
 150         bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
 151                                 XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
 152                                 BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
 153         if (!bp)
 154                 return EIO;
 155         xfs_buf_relse(bp);
 156
 157         new = nb;       /* use new as a temporary here */
 158         nb_mod = do_div(new, mp->m_sb.sb_agblocks);
 159         nagcount = new + (nb_mod != 0);
 160         if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
 161                 nagcount--;
 162                 nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
 163                 if (nb < mp->m_sb.sb_dblocks)
 164                         return XFS_ERROR(EINVAL);
 165         }
 166         new = nb - mp->m_sb.sb_dblocks;
 167         oagcount = mp->m_sb.sb_agcount;
 168
 169         /* allocate the new per-ag structures */
 170         if (nagcount > oagcount) {
 171                 error = xfs_initialize_perag(mp, nagcount, &nagimax);
 172                 if (error)
 173                         return error;
 174         }
 175
 176         tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
 177         tp->t_flags |= XFS_TRANS_RESERVE;
 178         if ((error = xfs_trans_reserve(tp, XFS_GROWFS_SPACE_RES(mp),
 179                         XFS_GROWDATA_LOG_RES(mp), 0, 0, 0))) {
 180                 xfs_trans_cancel(tp, 0);
 181                 return error;
 182         }
 183
 184         /*
 185          * Write new AG headers to disk. Non-transactional, but written
 186          * synchronously so they are completed prior to the growfs transaction
 187          * being logged.
 188          */
 189         nfree = 0;
 190         for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
 191                 /*
 192                  * AG freelist header block
 193                  */
 194                 bp = xfs_buf_get(mp->m_ddev_targp,
 195                                  XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
 196                                  XFS_FSS_TO_BB(mp, 1), XBF_LOCK | XBF_MAPPED);
 197                 agf = XFS_BUF_TO_AGF(bp);
 198                 memset(agf, 0, mp->m_sb.sb_sectsize);
 199                 agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
 200                 agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
 201                 agf->agf_seqno = cpu_to_be32(agno);
 202                 if (agno == nagcount - 1)
 203                         agsize =
 204                                 nb -
 205                                 (agno * (xfs_rfsblock_t)mp->m_sb.sb_agblocks);
 206                 else
 207                         agsize = mp->m_sb.sb_agblocks;
 208                 agf->agf_length = cpu_to_be32(agsize);
 209                 agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
 210                 agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
 211                 agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
 212                 agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
 213                 agf->agf_flfirst = 0;
 214                 agf->agf_fllast = cpu_to_be32(XFS_AGFL_SIZE(mp) - 1);
 215                 agf->agf_flcount = 0;
 216                 tmpsize = agsize - XFS_PREALLOC_BLOCKS(mp);
 217                 agf->agf_freeblks = cpu_to_be32(tmpsize);
 218                 agf->agf_longest = cpu_to_be32(tmpsize);
 219                 error = xfs_bwrite(mp, bp);
 220                 if (error) {
 221                         goto error0;
 222                 }
 223                 /*
 224                  * AG inode header block
 225                  */
 226                 bp = xfs_buf_get(mp->m_ddev_targp,
 227                                  XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
 228                                  XFS_FSS_TO_BB(mp, 1), XBF_LOCK | XBF_MAPPED);
 229                 agi = XFS_BUF_TO_AGI(bp);
 230                 memset(agi, 0, mp->m_sb.sb_sectsize);
 231                 agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
 232                 agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
 233                 agi->agi_seqno = cpu_to_be32(agno);
 234                 agi->agi_length = cpu_to_be32(agsize);
 235                 agi->agi_count = 0;
 236                 agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
 237                 agi->agi_level = cpu_to_be32(1);
 238                 agi->agi_freecount = 0;
 239                 agi->agi_newino = cpu_to_be32(NULLAGINO);
 240                 agi->agi_dirino = cpu_to_be32(NULLAGINO);
 241                 for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
 242                         agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
 243                 error = xfs_bwrite(mp, bp);
 244                 if (error) {
 245                         goto error0;
 246                 }
 247                 /*
 248                  * BNO btree root block
 249                  */
 250                 bp = xfs_buf_get(mp->m_ddev_targp,
 251                                  XFS_AGB_TO_DADDR(mp, agno, XFS_BNO_BLOCK(mp)),
 252                                  BTOBB(mp->m_sb.sb_blocksize),
 253                                  XBF_LOCK | XBF_MAPPED);
 254                 block = XFS_BUF_TO_BLOCK(bp);
 255                 memset(block, 0, mp->m_sb.sb_blocksize);
 256                 block->bb_magic = cpu_to_be32(XFS_ABTB_MAGIC);
 257                 block->bb_level = 0;
 258                 block->bb_numrecs = cpu_to_be16(1);
 259                 block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
 260                 block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
 261                 arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
 262                 arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
 263                 arec->ar_blockcount = cpu_to_be32(
 264                         agsize - be32_to_cpu(arec->ar_startblock));
 265                 error = xfs_bwrite(mp, bp);
 266                 if (error) {
 267                         goto error0;
 268                 }
 269                 /*
 270                  * CNT btree root block
 271                  */
 272                 bp = xfs_buf_get(mp->m_ddev_targp,
 273                                  XFS_AGB_TO_DADDR(mp, agno, XFS_CNT_BLOCK(mp)),
 274                                  BTOBB(mp->m_sb.sb_blocksize),
 275                                  XBF_LOCK | XBF_MAPPED);
 276                 block = XFS_BUF_TO_BLOCK(bp);
 277                 memset(block, 0, mp->m_sb.sb_blocksize);
 278                 block->bb_magic = cpu_to_be32(XFS_ABTC_MAGIC);
 279                 block->bb_level = 0;
 280                 block->bb_numrecs = cpu_to_be16(1);
 281                 block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
 282                 block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
 283                 arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
 284                 arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
 285                 arec->ar_blockcount = cpu_to_be32(
 286                         agsize - be32_to_cpu(arec->ar_startblock));
 287                 nfree += be32_to_cpu(arec->ar_blockcount);
 288                 error = xfs_bwrite(mp, bp);
 289                 if (error) {
 290                         goto error0;
 291                 }
 292                 /*
 293                  * INO btree root block
 294                  */
 295                 bp = xfs_buf_get(mp->m_ddev_targp,
 296                                  XFS_AGB_TO_DADDR(mp, agno, XFS_IBT_BLOCK(mp)),
 297                                  BTOBB(mp->m_sb.sb_blocksize),
 298                                  XBF_LOCK | XBF_MAPPED);
 299                 block = XFS_BUF_TO_BLOCK(bp);
 300                 memset(block, 0, mp->m_sb.sb_blocksize);
 301                 block->bb_magic = cpu_to_be32(XFS_IBT_MAGIC);
 302                 block->bb_level = 0;
 303                 block->bb_numrecs = 0;
 304                 block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
 305                 block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
 306                 error = xfs_bwrite(mp, bp);
 307                 if (error) {
 308                         goto error0;
 309                 }
 310         }
 311         xfs_trans_agblocks_delta(tp, nfree);
 312         /*
 313          * There are new blocks in the old last a.g.
 314          */
 315         if (new) {
 316                 /*
 317                  * Change the agi length.
 318                  */
 319                 error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
 320                 if (error) {
 321                         goto error0;
 322                 }
 323                 ASSERT(bp);
 324                 agi = XFS_BUF_TO_AGI(bp);
 325                 be32_add_cpu(&agi->agi_length, new);
 326                 ASSERT(nagcount == oagcount ||
 327                        be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
 328                 xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
 329                 /*
 330                  * Change agf length.
 331                  */
 332                 error = xfs_alloc_read_agf(mp, tp, agno, 0, &bp);
 333                 if (error) {
 334                         goto error0;
 335                 }
 336                 ASSERT(bp);
 337                 agf = XFS_BUF_TO_AGF(bp);
 338                 be32_add_cpu(&agf->agf_length, new);
 339                 ASSERT(be32_to_cpu(agf->agf_length) ==
 340                        be32_to_cpu(agi->agi_length));
 341
 342                 xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);
 343                 /*
 344                  * Free the new space.
 345                  */
 346                 error = xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, agno,
 347                         be32_to_cpu(agf->agf_length) - new), new);
 348                 if (error) {
 349                         goto error0;
 350                 }
 351         }
 352
 353         /*
 354          * Update changed superblock fields transactionally. These are not
 355          * seen by the rest of the world until the transaction commit applies
 356          * them atomically to the superblock.
 357          */
 358         if (nagcount > oagcount)
 359                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
 360         if (nb > mp->m_sb.sb_dblocks)
 361                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
 362                                  nb - mp->m_sb.sb_dblocks);
 363         if (nfree)
 364                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, nfree);
 365         if (dpct)
 366                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
 367         error = xfs_trans_commit(tp, 0);
 368         if (error)
 369                 return error;
 370
 371         /* New allocation groups fully initialized, so update mount struct */
 372         if (nagimax)
 373                 mp->m_maxagi = nagimax;
 374         if (mp->m_sb.sb_imax_pct) {
 375                 __uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
 376                 do_div(icount, 100);
 377                 mp->m_maxicount = icount << mp->m_sb.sb_inopblog;
 378         } else
 379                 mp->m_maxicount = 0;
 380         xfs_set_low_space_thresholds(mp);
 381
 382         /* update secondary superblocks. */
 383         for (agno = 1; agno < nagcount; agno++) {
 384                 error = xfs_read_buf(mp, mp->m_ddev_targp,
 385                                   XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
 386                                   XFS_FSS_TO_BB(mp, 1), 0, &bp);
 387                 if (error) {
 388                         xfs_warn(mp,
 389                 "error %d reading secondary superblock for ag %d",
 390                                 error, agno);
 391                         break;
 392                 }
 393                 xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, XFS_SB_ALL_BITS);
 394                 /*
 395                  * If we get an error writing out the alternate superblocks,
 396                  * just issue a warning and continue.  The real work is
 397                  * already done and committed.
 398                  */
 399                 if (!(error = xfs_bwrite(mp, bp))) {
 400                         continue;
 401                 } else {
 402                         xfs_warn(mp,
 403                 "write error %d updating secondary superblock for ag %d",
 404                                 error, agno);
 405                         break; /* no point in continuing */
 406                 }
 407         }
 408         return 0;
 409
 410  error0:
 411         xfs_trans_cancel(tp, XFS_TRANS_ABORT);
 412         return error;
 413 }
 414
 415 static int
 416 xfs_growfs_log_private(
 417         xfs_mount_t             *mp,    /* mount point for filesystem */
 418         xfs_growfs_log_t        *in)    /* growfs log input struct */
 419 {
 420         xfs_extlen_t            nb;
 421
 422         nb = in->newblocks;
 423         if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
 424                 return XFS_ERROR(EINVAL);
 425         if (nb == mp->m_sb.sb_logblocks &&
 426             in->isint == (mp->m_sb.sb_logstart != 0))
 427                 return XFS_ERROR(EINVAL);
 428         /*
 429          * Moving the log is hard, need new interfaces to sync
 430          * the log first, hold off all activity while moving it.
 431          * Can have shorter or longer log in the same space,
 432          * or transform internal to external log or vice versa.
 433          */
 434         return XFS_ERROR(ENOSYS);
 435 }
 436
 437 /*
 438  * protected versions of growfs function acquire and release locks on the mount
 439  * point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
 440  * XFS_IOC_FSGROWFSRT
 441  */
 442
 443
 444 int
 445 xfs_growfs_data(
 446         xfs_mount_t             *mp,
 447         xfs_growfs_data_t       *in)
 448 {
 449         int error;
 450
 451         if (!capable(CAP_SYS_ADMIN))
 452                 return XFS_ERROR(EPERM);
 453         if (!mutex_trylock(&mp->m_growlock))
 454                 return XFS_ERROR(EWOULDBLOCK);
 455         error = xfs_growfs_data_private(mp, in);
 456         mutex_unlock(&mp->m_growlock);
 457         return error;
 458 }
 459
 460 int
 461 xfs_growfs_log(
 462         xfs_mount_t             *mp,
 463         xfs_growfs_log_t        *in)
 464 {
 465         int error;
 466
 467         if (!capable(CAP_SYS_ADMIN))
 468                 return XFS_ERROR(EPERM);
 469         if (!mutex_trylock(&mp->m_growlock))
 470                 return XFS_ERROR(EWOULDBLOCK);
 471         error = xfs_growfs_log_private(mp, in);
 472         mutex_unlock(&mp->m_growlock);
 473         return error;
 474 }
 475
 476 /*
 477  * exported through ioctl XFS_IOC_FSCOUNTS
 478  */
 479
 480 int
 481 xfs_fs_counts(
 482         xfs_mount_t             *mp,
 483         xfs_fsop_counts_t       *cnt)
 484 {
 485         xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
 486         spin_lock(&mp->m_sb_lock);
 487         cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
 488         cnt->freertx = mp->m_sb.sb_frextents;
 489         cnt->freeino = mp->m_sb.sb_ifree;
 490         cnt->allocino = mp->m_sb.sb_icount;
 491         spin_unlock(&mp->m_sb_lock);
 492         return 0;
 493 }
 494
 495 /*
 496  * exported through ioctl XFS_IOC_SET_RESBLKS & XFS_IOC_GET_RESBLKS
 497  *
 498  * xfs_reserve_blocks is called to set m_resblks
 499  * in the in-core mount table. The number of unused reserved blocks
 500  * is kept in m_resblks_avail.
 501  *
 502  * Reserve the requested number of blocks if available. Otherwise return
 503  * as many as possible to satisfy the request. The actual number
 504  * reserved are returned in outval
 505  *
 506  * A null inval pointer indicates that only the current reserved blocks
 507  * available  should  be returned no settings are changed.
 508  */
 509
 510 int
 511 xfs_reserve_blocks(
 512         xfs_mount_t             *mp,
 513         __uint64_t              *inval,
 514         xfs_fsop_resblks_t      *outval)
 515 {
 516         __int64_t               lcounter, delta, fdblks_delta;
 517         __uint64_t              request;
 518
 519         /* If inval is null, report current values and return */
 520         if (inval == (__uint64_t *)NULL) {
 521                 if (!outval)
 522                         return EINVAL;
 523                 outval->resblks = mp->m_resblks;
 524                 outval->resblks_avail = mp->m_resblks_avail;
 525                 return 0;
 526         }
 527
 528         request = *inval;
 529
 530         /*
 531          * With per-cpu counters, this becomes an interesting
 532          * problem. we needto work out if we are freeing or allocation
 533          * blocks first, then we can do the modification as necessary.
 534          *
 535          * We do this under the m_sb_lock so that if we are near
 536          * ENOSPC, we will hold out any changes while we work out
 537          * what to do. This means that the amount of free space can
 538          * change while we do this, so we need to retry if we end up
 539          * trying to reserve more space than is available.
 540          *
 541          * We also use the xfs_mod_incore_sb() interface so that we
 542          * don't have to care about whether per cpu counter are
 543          * enabled, disabled or even compiled in....
 544          */
 545 retry:
 546         spin_lock(&mp->m_sb_lock);
 547         xfs_icsb_sync_counters_locked(mp, 0);
 548
 549         /*
 550          * If our previous reservation was larger than the current value,
 551          * then move any unused blocks back to the free pool.
 552          */
 553         fdblks_delta = 0;
 554         if (mp->m_resblks > request) {
 555                 lcounter = mp->m_resblks_avail - request;
 556                 if (lcounter  > 0) {            /* release unused blocks */
 557                         fdblks_delta = lcounter;
 558                         mp->m_resblks_avail -= lcounter;
 559                 }
 560                 mp->m_resblks = request;
 561         } else {
 562                 __int64_t       free;
 563
 564                 free =  mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
 565                 if (!free)
 566                         goto out; /* ENOSPC and fdblks_delta = 0 */
 567
 568                 delta = request - mp->m_resblks;
 569                 lcounter = free - delta;
 570                 if (lcounter < 0) {
 571                         /* We can't satisfy the request, just get what we can */
 572                         mp->m_resblks += free;
 573                         mp->m_resblks_avail += free;
 574                         fdblks_delta = -free;
 575                 } else {
 576                         fdblks_delta = -delta;
 577                         mp->m_resblks = request;
 578                         mp->m_resblks_avail += delta;
 579                 }
 580         }
 581 out:
 582         if (outval) {
 583                 outval->resblks = mp->m_resblks;
 584                 outval->resblks_avail = mp->m_resblks_avail;
 585         }
 586         spin_unlock(&mp->m_sb_lock);
 587
 588         if (fdblks_delta) {
 589                 /*
 590                  * If we are putting blocks back here, m_resblks_avail is
 591                  * already at its max so this will put it in the free pool.
 592                  *
 593                  * If we need space, we'll either succeed in getting it
 594                  * from the free block count or we'll get an enospc. If
 595                  * we get a ENOSPC, it means things changed while we were
 596                  * calculating fdblks_delta and so we should try again to
 597                  * see if there is anything left to reserve.
 598                  *
 599                  * Don't set the reserved flag here - we don't want to reserve
 600                  * the extra reserve blocks from the reserve.....
 601                  */
 602                 int error;
 603                 error = xfs_icsb_modify_counters(mp, XFS_SBS_FDBLOCKS,
 604                                                  fdblks_delta, 0);
 605                 if (error == ENOSPC)
 606                         goto retry;
 607         }
 608         return 0;
 609 }
 610
 611 /*
 612  * Dump a transaction into the log that contains no real change. This is needed
 613  * to be able to make the log dirty or stamp the current tail LSN into the log
 614  * during the covering operation.
 615  *
 616  * We cannot use an inode here for this - that will push dirty state back up
 617  * into the VFS and then periodic inode flushing will prevent log covering from
 618  * making progress. Hence we log a field in the superblock instead and use a
 619  * synchronous transaction to ensure the superblock is immediately unpinned
 620  * and can be written back.
 621  */
 622 int
 623 xfs_fs_log_dummy(
 624         xfs_mount_t     *mp)
 625 {
 626         xfs_trans_t     *tp;
 627         int             error;
 628
 629         tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
 630         error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
 631                                         XFS_DEFAULT_LOG_COUNT);
 632         if (error) {
 633                 xfs_trans_cancel(tp, 0);
 634                 return error;
 635         }
 636
 637         /* log the UUID because it is an unchanging field */
 638         xfs_mod_sb(tp, XFS_SB_UUID);
 639         xfs_trans_set_sync(tp);
 640         return xfs_trans_commit(tp, 0);
 641 }
 642
 643 int
 644 xfs_fs_goingdown(
 645         xfs_mount_t     *mp,
 646         __uint32_t      inflags)
 647 {
 648         switch (inflags) {
 649         case XFS_FSOP_GOING_FLAGS_DEFAULT: {
 650                 struct super_block *sb = freeze_bdev(mp->m_super->s_bdev);
 651
 652                 if (sb && !IS_ERR(sb)) {
 653                         xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
 654                         thaw_bdev(sb->s_bdev, sb);
 655                 }
 656
 657                 break;
 658         }
 659         case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
 660                 xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
 661                 break;
 662         case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
 663                 xfs_force_shutdown(mp,
 664                                 SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
 665                 break;
 666         default:
 667                 return XFS_ERROR(EINVAL);
 668         }
 669
 670         return 0;
 671 }