fs/xfs/xfs_symlink.c

   1 /*
   2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3  * Copyright (c) 2012-2013 Red Hat, Inc.
   4  * All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it would be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write the Free Software Foundation,
  17  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19 #include "xfs.h"
  20 #include "xfs_fs.h"
  21 #include "xfs_format.h"
  22 #include "xfs_bit.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_da_btree.h"
  29 #include "xfs_dir2_format.h"
  30 #include "xfs_dir2.h"
  31 #include "xfs_bmap_btree.h"
  32 #include "xfs_ialloc_btree.h"
  33 #include "xfs_dinode.h"
  34 #include "xfs_inode.h"
  35 #include "xfs_inode_item.h"
  36 #include "xfs_itable.h"
  37 #include "xfs_ialloc.h"
  38 #include "xfs_alloc.h"
  39 #include "xfs_bmap.h"
  40 #include "xfs_error.h"
  41 #include "xfs_quota.h"
  42 #include "xfs_utils.h"
  43 #include "xfs_trans_space.h"
  44 #include "xfs_log_priv.h"
  45 #include "xfs_trace.h"
  46 #include "xfs_symlink.h"
  47 #include "xfs_cksum.h"
  48 #include "xfs_buf_item.h"
  49
  50
  51 /*
  52  * Each contiguous block has a header, so it is not just a simple pathlen
  53  * to FSB conversion.
  54  */
  55 int
  56 xfs_symlink_blocks(
  57         struct xfs_mount *mp,
  58         int             pathlen)
  59 {
  60         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  61
  62         return (pathlen + buflen - 1) / buflen;
  63 }
  64
  65 static int
  66 xfs_symlink_hdr_set(
  67         struct xfs_mount        *mp,
  68         xfs_ino_t               ino,
  69         uint32_t                offset,
  70         uint32_t                size,
  71         struct xfs_buf          *bp)
  72 {
  73         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  74
  75         if (!xfs_sb_version_hascrc(&mp->m_sb))
  76                 return 0;
  77
  78         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  79         dsl->sl_offset = cpu_to_be32(offset);
  80         dsl->sl_bytes = cpu_to_be32(size);
  81         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
  82         dsl->sl_owner = cpu_to_be64(ino);
  83         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  84         bp->b_ops = &xfs_symlink_buf_ops;
  85
  86         return sizeof(struct xfs_dsymlink_hdr);
  87 }
  88
  89 /*
  90  * Checking of the symlink header is split into two parts. the verifier does
  91  * CRC, location and bounds checking, the unpacking function checks the path
  92  * parameters and owner.
  93  */
  94 bool
  95 xfs_symlink_hdr_ok(
  96         struct xfs_mount        *mp,
  97         xfs_ino_t               ino,
  98         uint32_t                offset,
  99         uint32_t                size,
 100         struct xfs_buf          *bp)
 101 {
 102         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 103
 104         if (offset != be32_to_cpu(dsl->sl_offset))
 105                 return false;
 106         if (size != be32_to_cpu(dsl->sl_bytes))
 107                 return false;
 108         if (ino != be64_to_cpu(dsl->sl_owner))
 109                 return false;
 110
 111         /* ok */
 112         return true;
 113 }
 114
 115 static bool
 116 xfs_symlink_verify(
 117         struct xfs_buf          *bp)
 118 {
 119         struct xfs_mount        *mp = bp->b_target->bt_mount;
 120         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 121
 122         if (!xfs_sb_version_hascrc(&mp->m_sb))
 123                 return false;
 124         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 125                 return false;
 126         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
 127                 return false;
 128         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 129                 return false;
 130         if (be32_to_cpu(dsl->sl_offset) +
 131                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 132                 return false;
 133         if (dsl->sl_owner == 0)
 134                 return false;
 135
 136         return true;
 137 }
 138
 139 static void
 140 xfs_symlink_read_verify(
 141         struct xfs_buf  *bp)
 142 {
 143         struct xfs_mount *mp = bp->b_target->bt_mount;
 144
 145         /* no verification of non-crc buffers */
 146         if (!xfs_sb_version_hascrc(&mp->m_sb))
 147                 return;
 148
 149         if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 150                                   offsetof(struct xfs_dsymlink_hdr, sl_crc)) ||
 151             !xfs_symlink_verify(bp)) {
 152                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 153                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 154         }
 155 }
 156
 157 static void
 158 xfs_symlink_write_verify(
 159         struct xfs_buf  *bp)
 160 {
 161         struct xfs_mount *mp = bp->b_target->bt_mount;
 162         struct xfs_buf_log_item *bip = bp->b_fspriv;
 163
 164         /* no verification of non-crc buffers */
 165         if (!xfs_sb_version_hascrc(&mp->m_sb))
 166                 return;
 167
 168         if (!xfs_symlink_verify(bp)) {
 169                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 170                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 171                 return;
 172         }
 173
 174         if (bip) {
 175                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 176                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 177         }
 178         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 179                          offsetof(struct xfs_dsymlink_hdr, sl_crc));
 180 }
 181
 182 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 183         .verify_read = xfs_symlink_read_verify,
 184         .verify_write = xfs_symlink_write_verify,
 185 };
 186
 187 void
 188 xfs_symlink_local_to_remote(
 189         struct xfs_trans        *tp,
 190         struct xfs_buf          *bp,
 191         struct xfs_inode        *ip,
 192         struct xfs_ifork        *ifp)
 193 {
 194         struct xfs_mount        *mp = ip->i_mount;
 195         char                    *buf;
 196
 197         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 198                 bp->b_ops = NULL;
 199                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 200                 return;
 201         }
 202
 203         /*
 204          * As this symlink fits in an inode literal area, it must also fit in
 205          * the smallest buffer the filesystem supports.
 206          */
 207         ASSERT(BBTOB(bp->b_length) >=
 208                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 209
 210         bp->b_ops = &xfs_symlink_buf_ops;
 211
 212         buf = bp->b_addr;
 213         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 214         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 215 }
 216
 217 /* ----- Kernel only functions below ----- */
 218 STATIC int
 219 xfs_readlink_bmap(
 220         struct xfs_inode        *ip,
 221         char                    *link)
 222 {
 223         struct xfs_mount        *mp = ip->i_mount;
 224         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 225         struct xfs_buf          *bp;
 226         xfs_daddr_t             d;
 227         char                    *cur_chunk;
 228         int                     pathlen = ip->i_d.di_size;
 229         int                     nmaps = XFS_SYMLINK_MAPS;
 230         int                     byte_cnt;
 231         int                     n;
 232         int                     error = 0;
 233         int                     fsblocks = 0;
 234         int                     offset;
 235
 236         fsblocks = xfs_symlink_blocks(mp, pathlen);
 237         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
 238         if (error)
 239                 goto out;
 240
 241         offset = 0;
 242         for (n = 0; n < nmaps; n++) {
 243                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 244                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 245
 246                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
 247                                   &xfs_symlink_buf_ops);
 248                 if (!bp)
 249                         return XFS_ERROR(ENOMEM);
 250                 error = bp->b_error;
 251                 if (error) {
 252                         xfs_buf_ioerror_alert(bp, __func__);
 253                         xfs_buf_relse(bp);
 254                         goto out;
 255                 }
 256                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 257                 if (pathlen < byte_cnt)
 258                         byte_cnt = pathlen;
 259
 260                 cur_chunk = bp->b_addr;
 261                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
 262                         if (!xfs_symlink_hdr_ok(mp, ip->i_ino, offset,
 263                                                         byte_cnt, bp)) {
 264                                 error = EFSCORRUPTED;
 265                                 xfs_alert(mp,
 266 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
 267                                         offset, byte_cnt, ip->i_ino);
 268                                 xfs_buf_relse(bp);
 269                                 goto out;
 270
 271                         }
 272
 273                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 274                 }
 275
 276                 memcpy(link + offset, bp->b_addr, byte_cnt);
 277
 278                 pathlen -= byte_cnt;
 279                 offset += byte_cnt;
 280
 281                 xfs_buf_relse(bp);
 282         }
 283         ASSERT(pathlen == 0);
 284
 285         link[ip->i_d.di_size] = '\0';
 286         error = 0;
 287
 288  out:
 289         return error;
 290 }
 291
 292 int
 293 xfs_readlink(
 294         struct xfs_inode *ip,
 295         char            *link)
 296 {
 297         struct xfs_mount *mp = ip->i_mount;
 298         xfs_fsize_t     pathlen;
 299         int             error = 0;
 300
 301         trace_xfs_readlink(ip);
 302
 303         if (XFS_FORCED_SHUTDOWN(mp))
 304                 return XFS_ERROR(EIO);
 305
 306         xfs_ilock(ip, XFS_ILOCK_SHARED);
 307
 308         pathlen = ip->i_d.di_size;
 309         if (!pathlen)
 310                 goto out;
 311
 312         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 313                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 314                          __func__, (unsigned long long) ip->i_ino,
 315                          (long long) pathlen);
 316                 ASSERT(0);
 317                 error = XFS_ERROR(EFSCORRUPTED);
 318                 goto out;
 319         }
 320
 321
 322         if (ip->i_df.if_flags & XFS_IFINLINE) {
 323                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 324                 link[pathlen] = '\0';
 325         } else {
 326                 error = xfs_readlink_bmap(ip, link);
 327         }
 328
 329  out:
 330         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 331         return error;
 332 }
 333
 334 int
 335 xfs_symlink(
 336         struct xfs_inode        *dp,
 337         struct xfs_name         *link_name,
 338         const char              *target_path,
 339         umode_t                 mode,
 340         struct xfs_inode        **ipp)
 341 {
 342         struct xfs_mount        *mp = dp->i_mount;
 343         struct xfs_trans        *tp = NULL;
 344         struct xfs_inode        *ip = NULL;
 345         int                     error = 0;
 346         int                     pathlen;
 347         struct xfs_bmap_free    free_list;
 348         xfs_fsblock_t           first_block;
 349         bool                    unlock_dp_on_error = false;
 350         uint                    cancel_flags;
 351         int                     committed;
 352         xfs_fileoff_t           first_fsb;
 353         xfs_filblks_t           fs_blocks;
 354         int                     nmaps;
 355         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 356         xfs_daddr_t             d;
 357         const char              *cur_chunk;
 358         int                     byte_cnt;
 359         int                     n;
 360         xfs_buf_t               *bp;
 361         prid_t                  prid;
 362         struct xfs_dquot        *udqp = NULL;
 363         struct xfs_dquot        *gdqp = NULL;
 364         struct xfs_dquot        *pdqp = NULL;
 365         uint                    resblks;
 366
 367         *ipp = NULL;
 368
 369         trace_xfs_symlink(dp, link_name);
 370
 371         if (XFS_FORCED_SHUTDOWN(mp))
 372                 return XFS_ERROR(EIO);
 373
 374         /*
 375          * Check component lengths of the target path name.
 376          */
 377         pathlen = strlen(target_path);
 378         if (pathlen >= MAXPATHLEN)      /* total string too long */
 379                 return XFS_ERROR(ENAMETOOLONG);
 380
 381         udqp = gdqp = NULL;
 382         if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
 383                 prid = xfs_get_projid(dp);
 384         else
 385                 prid = XFS_PROJID_DEFAULT;
 386
 387         /*
 388          * Make sure that we have allocated dquot(s) on disk.
 389          */
 390         error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
 391                 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, &udqp, &gdqp, &pdqp);
 392         if (error)
 393                 goto std_return;
 394
 395         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 396         cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 397         /*
 398          * The symlink will fit into the inode data fork?
 399          * There can't be any attributes so we get the whole variable part.
 400          */
 401         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 402                 fs_blocks = 0;
 403         else
 404                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 405         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 406         error = xfs_trans_reserve(tp, resblks, XFS_SYMLINK_LOG_RES(mp), 0,
 407                         XFS_TRANS_PERM_LOG_RES, XFS_SYMLINK_LOG_COUNT);
 408         if (error == ENOSPC && fs_blocks == 0) {
 409                 resblks = 0;
 410                 error = xfs_trans_reserve(tp, 0, XFS_SYMLINK_LOG_RES(mp), 0,
 411                                 XFS_TRANS_PERM_LOG_RES, XFS_SYMLINK_LOG_COUNT);
 412         }
 413         if (error) {
 414                 cancel_flags = 0;
 415                 goto error_return;
 416         }
 417
 418         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 419         unlock_dp_on_error = true;
 420
 421         /*
 422          * Check whether the directory allows new symlinks or not.
 423          */
 424         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 425                 error = XFS_ERROR(EPERM);
 426                 goto error_return;
 427         }
 428
 429         /*
 430          * Reserve disk quota : blocks and inode.
 431          */
 432         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 433                                                 pdqp, resblks, 1, 0);
 434         if (error)
 435                 goto error_return;
 436
 437         /*
 438          * Check for ability to enter directory entry, if no space reserved.
 439          */
 440         error = xfs_dir_canenter(tp, dp, link_name, resblks);
 441         if (error)
 442                 goto error_return;
 443         /*
 444          * Initialize the bmap freelist prior to calling either
 445          * bmapi or the directory create code.
 446          */
 447         xfs_bmap_init(&free_list, &first_block);
 448
 449         /*
 450          * Allocate an inode for the symlink.
 451          */
 452         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 453                                prid, resblks > 0, &ip, NULL);
 454         if (error) {
 455                 if (error == ENOSPC)
 456                         goto error_return;
 457                 goto error1;
 458         }
 459
 460         /*
 461          * An error after we've joined dp to the transaction will result in the
 462          * transaction cancel unlocking dp so don't do it explicitly in the
 463          * error path.
 464          */
 465         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 466         unlock_dp_on_error = false;
 467
 468         /*
 469          * Also attach the dquot(s) to it, if applicable.
 470          */
 471         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 472
 473         if (resblks)
 474                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 475         /*
 476          * If the symlink will fit into the inode, write it inline.
 477          */
 478         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 479                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 480                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 481                 ip->i_d.di_size = pathlen;
 482
 483                 /*
 484                  * The inode was initially created in extent format.
 485                  */
 486                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 487                 ip->i_df.if_flags |= XFS_IFINLINE;
 488
 489                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 490                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 491
 492         } else {
 493                 int     offset;
 494
 495                 first_fsb = 0;
 496                 nmaps = XFS_SYMLINK_MAPS;
 497
 498                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 499                                   XFS_BMAPI_METADATA, &first_block, resblks,
 500                                   mval, &nmaps, &free_list);
 501                 if (error)
 502                         goto error2;
 503
 504                 if (resblks)
 505                         resblks -= fs_blocks;
 506                 ip->i_d.di_size = pathlen;
 507                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 508
 509                 cur_chunk = target_path;
 510                 offset = 0;
 511                 for (n = 0; n < nmaps; n++) {
 512                         char    *buf;
 513
 514                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 515                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 516                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 517                                                BTOBB(byte_cnt), 0);
 518                         if (!bp) {
 519                                 error = ENOMEM;
 520                                 goto error2;
 521                         }
 522                         bp->b_ops = &xfs_symlink_buf_ops;
 523
 524                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 525                         byte_cnt = min(byte_cnt, pathlen);
 526
 527                         buf = bp->b_addr;
 528                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 529                                                    byte_cnt, bp);
 530
 531                         memcpy(buf, cur_chunk, byte_cnt);
 532
 533                         cur_chunk += byte_cnt;
 534                         pathlen -= byte_cnt;
 535                         offset += byte_cnt;
 536
 537                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 538                                                         (char *)bp->b_addr);
 539                 }
 540                 ASSERT(pathlen == 0);
 541         }
 542
 543         /*
 544          * Create the directory entry for the symlink.
 545          */
 546         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 547                                         &first_block, &free_list, resblks);
 548         if (error)
 549                 goto error2;
 550         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 551         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 552
 553         /*
 554          * If this is a synchronous mount, make sure that the
 555          * symlink transaction goes to disk before returning to
 556          * the user.
 557          */
 558         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 559                 xfs_trans_set_sync(tp);
 560         }
 561
 562         error = xfs_bmap_finish(&tp, &free_list, &committed);
 563         if (error) {
 564                 goto error2;
 565         }
 566         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 567         xfs_qm_dqrele(udqp);
 568         xfs_qm_dqrele(gdqp);
 569         xfs_qm_dqrele(pdqp);
 570
 571         *ipp = ip;
 572         return 0;
 573
 574  error2:
 575         IRELE(ip);
 576  error1:
 577         xfs_bmap_cancel(&free_list);
 578         cancel_flags |= XFS_TRANS_ABORT;
 579  error_return:
 580         xfs_trans_cancel(tp, cancel_flags);
 581         xfs_qm_dqrele(udqp);
 582         xfs_qm_dqrele(gdqp);
 583         xfs_qm_dqrele(pdqp);
 584
 585         if (unlock_dp_on_error)
 586                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 587  std_return:
 588         return error;
 589 }
 590
 591 /*
 592  * Free a symlink that has blocks associated with it.
 593  */
 594 STATIC int
 595 xfs_inactive_symlink_rmt(
 596         xfs_inode_t     *ip,
 597         xfs_trans_t     **tpp)
 598 {
 599         xfs_buf_t       *bp;
 600         int             committed;
 601         int             done;
 602         int             error;
 603         xfs_fsblock_t   first_block;
 604         xfs_bmap_free_t free_list;
 605         int             i;
 606         xfs_mount_t     *mp;
 607         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 608         int             nmaps;
 609         xfs_trans_t     *ntp;
 610         int             size;
 611         xfs_trans_t     *tp;
 612
 613         tp = *tpp;
 614         mp = ip->i_mount;
 615         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 616         /*
 617          * We're freeing a symlink that has some
 618          * blocks allocated to it.  Free the
 619          * blocks here.  We know that we've got
 620          * either 1 or 2 extents and that we can
 621          * free them all in one bunmapi call.
 622          */
 623         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 624
 625         /*
 626          * Lock the inode, fix the size, and join it to the transaction.
 627          * Hold it so in the normal path, we still have it locked for
 628          * the second transaction.  In the error paths we need it
 629          * held so the cancel won't rele it, see below.
 630          */
 631         size = (int)ip->i_d.di_size;
 632         ip->i_d.di_size = 0;
 633         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 634         /*
 635          * Find the block(s) so we can inval and unmap them.
 636          */
 637         done = 0;
 638         xfs_bmap_init(&free_list, &first_block);
 639         nmaps = ARRAY_SIZE(mval);
 640         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 641                                 mval, &nmaps, 0);
 642         if (error)
 643                 goto error0;
 644         /*
 645          * Invalidate the block(s). No validation is done.
 646          */
 647         for (i = 0; i < nmaps; i++) {
 648                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 649                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 650                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 651                 if (!bp) {
 652                         error = ENOMEM;
 653                         goto error1;
 654                 }
 655                 xfs_trans_binval(tp, bp);
 656         }
 657         /*
 658          * Unmap the dead block(s) to the free_list.
 659          */
 660         if ((error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 661                         &first_block, &free_list, &done)))
 662                 goto error1;
 663         ASSERT(done);
 664         /*
 665          * Commit the first transaction.  This logs the EFI and the inode.
 666          */
 667         if ((error = xfs_bmap_finish(&tp, &free_list, &committed)))
 668                 goto error1;
 669         /*
 670          * The transaction must have been committed, since there were
 671          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 672          * The new tp has the extent freeing and EFDs.
 673          */
 674         ASSERT(committed);
 675         /*
 676          * The first xact was committed, so add the inode to the new one.
 677          * Mark it dirty so it will be logged and moved forward in the log as
 678          * part of every commit.
 679          */
 680         xfs_trans_ijoin(tp, ip, 0);
 681         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 682         /*
 683          * Get a new, empty transaction to return to our caller.
 684          */
 685         ntp = xfs_trans_dup(tp);
 686         /*
 687          * Commit the transaction containing extent freeing and EFDs.
 688          * If we get an error on the commit here or on the reserve below,
 689          * we need to unlock the inode since the new transaction doesn't
 690          * have the inode attached.
 691          */
 692         error = xfs_trans_commit(tp, 0);
 693         tp = ntp;
 694         if (error) {
 695                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 696                 goto error0;
 697         }
 698         /*
 699          * transaction commit worked ok so we can drop the extra ticket
 700          * reference that we gained in xfs_trans_dup()
 701          */
 702         xfs_log_ticket_put(tp->t_ticket);
 703
 704         /*
 705          * Remove the memory for extent descriptions (just bookkeeping).
 706          */
 707         if (ip->i_df.if_bytes)
 708                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 709         ASSERT(ip->i_df.if_bytes == 0);
 710         /*
 711          * Put an itruncate log reservation in the new transaction
 712          * for our caller.
 713          */
 714         if ((error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0,
 715                         XFS_TRANS_PERM_LOG_RES, XFS_ITRUNCATE_LOG_COUNT))) {
 716                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 717                 goto error0;
 718         }
 719
 720         xfs_trans_ijoin(tp, ip, 0);
 721         *tpp = tp;
 722         return 0;
 723
 724  error1:
 725         xfs_bmap_cancel(&free_list);
 726  error0:
 727         return error;
 728 }
 729
 730 /*
 731  * xfs_inactive_symlink - free a symlink
 732  */
 733 int
 734 xfs_inactive_symlink(
 735         struct xfs_inode        *ip,
 736         struct xfs_trans        **tp)
 737 {
 738         struct xfs_mount        *mp = ip->i_mount;
 739         int                     pathlen;
 740
 741         trace_xfs_inactive_symlink(ip);
 742
 743         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 744
 745         if (XFS_FORCED_SHUTDOWN(mp))
 746                 return XFS_ERROR(EIO);
 747
 748         /*
 749          * Zero length symlinks _can_ exist.
 750          */
 751         pathlen = (int)ip->i_d.di_size;
 752         if (!pathlen)
 753                 return 0;
 754
 755         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 756                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 757                          __func__, (unsigned long long)ip->i_ino, pathlen);
 758                 ASSERT(0);
 759                 return XFS_ERROR(EFSCORRUPTED);
 760         }
 761
 762         if (ip->i_df.if_flags & XFS_IFINLINE) {
 763                 if (ip->i_df.if_bytes > 0)
 764                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 765                                           XFS_DATA_FORK);
 766                 ASSERT(ip->i_df.if_bytes == 0);
 767                 return 0;
 768         }
 769
 770         /* remove the remote symlink */
 771         return xfs_inactive_symlink_rmt(ip, tp);
 772 }