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_types.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_dir2.h"
  28 #include "xfs_mount.h"
  29 #include "xfs_da_btree.h"
  30 #include "xfs_bmap_btree.h"
  31 #include "xfs_ialloc_btree.h"
  32 #include "xfs_dinode.h"
  33 #include "xfs_inode.h"
  34 #include "xfs_inode_item.h"
  35 #include "xfs_itable.h"
  36 #include "xfs_ialloc.h"
  37 #include "xfs_alloc.h"
  38 #include "xfs_bmap.h"
  39 #include "xfs_error.h"
  40 #include "xfs_quota.h"
  41 #include "xfs_utils.h"
  42 #include "xfs_trans_space.h"
  43 #include "xfs_log_priv.h"
  44 #include "xfs_trace.h"
  45 #include "xfs_symlink.h"
  46 #include "xfs_cksum.h"
  47 #include "xfs_buf_item.h"
  48
  49
  50 /*
  51  * Each contiguous block has a header, so it is not just a simple pathlen
  52  * to FSB conversion.
  53  */
  54 int
  55 xfs_symlink_blocks(
  56         struct xfs_mount *mp,
  57         int             pathlen)
  58 {
  59         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  60
  61         return (pathlen + buflen - 1) / buflen;
  62 }
  63
  64 static int
  65 xfs_symlink_hdr_set(
  66         struct xfs_mount        *mp,
  67         xfs_ino_t               ino,
  68         uint32_t                offset,
  69         uint32_t                size,
  70         struct xfs_buf          *bp)
  71 {
  72         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  73
  74         if (!xfs_sb_version_hascrc(&mp->m_sb))
  75                 return 0;
  76
  77         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  78         dsl->sl_offset = cpu_to_be32(offset);
  79         dsl->sl_bytes = cpu_to_be32(size);
  80         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
  81         dsl->sl_owner = cpu_to_be64(ino);
  82         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  83         bp->b_ops = &xfs_symlink_buf_ops;
  84
  85         return sizeof(struct xfs_dsymlink_hdr);
  86 }
  87
  88 /*
  89  * Checking of the symlink header is split into two parts. the verifier does
  90  * CRC, location and bounds checking, the unpacking function checks the path
  91  * parameters and owner.
  92  */
  93 bool
  94 xfs_symlink_hdr_ok(
  95         struct xfs_mount        *mp,
  96         xfs_ino_t               ino,
  97         uint32_t                offset,
  98         uint32_t                size,
  99         struct xfs_buf          *bp)
 100 {
 101         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 102
 103         if (offset != be32_to_cpu(dsl->sl_offset))
 104                 return false;
 105         if (size != be32_to_cpu(dsl->sl_bytes))
 106                 return false;
 107         if (ino != be64_to_cpu(dsl->sl_owner))
 108                 return false;
 109
 110         /* ok */
 111         return true;
 112 }
 113
 114 static bool
 115 xfs_symlink_verify(
 116         struct xfs_buf          *bp)
 117 {
 118         struct xfs_mount        *mp = bp->b_target->bt_mount;
 119         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 120
 121         if (!xfs_sb_version_hascrc(&mp->m_sb))
 122                 return false;
 123         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 124                 return false;
 125         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
 126                 return false;
 127         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 128                 return false;
 129         if (be32_to_cpu(dsl->sl_offset) +
 130                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 131                 return false;
 132         if (dsl->sl_owner == 0)
 133                 return false;
 134
 135         return true;
 136 }
 137
 138 static void
 139 xfs_symlink_read_verify(
 140         struct xfs_buf  *bp)
 141 {
 142         struct xfs_mount *mp = bp->b_target->bt_mount;
 143
 144         /* no verification of non-crc buffers */
 145         if (!xfs_sb_version_hascrc(&mp->m_sb))
 146                 return;
 147
 148         if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 149                                   offsetof(struct xfs_dsymlink_hdr, sl_crc)) ||
 150             !xfs_symlink_verify(bp)) {
 151                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 152                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 153         }
 154 }
 155
 156 static void
 157 xfs_symlink_write_verify(
 158         struct xfs_buf  *bp)
 159 {
 160         struct xfs_mount *mp = bp->b_target->bt_mount;
 161         struct xfs_buf_log_item *bip = bp->b_fspriv;
 162
 163         /* no verification of non-crc buffers */
 164         if (!xfs_sb_version_hascrc(&mp->m_sb))
 165                 return;
 166
 167         if (!xfs_symlink_verify(bp)) {
 168                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 169                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 170                 return;
 171         }
 172
 173         if (bip) {
 174                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 175                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 176         }
 177         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 178                          offsetof(struct xfs_dsymlink_hdr, sl_crc));
 179 }
 180
 181 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 182         .verify_read = xfs_symlink_read_verify,
 183         .verify_write = xfs_symlink_write_verify,
 184 };
 185
 186 void
 187 xfs_symlink_local_to_remote(
 188         struct xfs_trans        *tp,
 189         struct xfs_buf          *bp,
 190         struct xfs_inode        *ip,
 191         struct xfs_ifork        *ifp)
 192 {
 193         struct xfs_mount        *mp = ip->i_mount;
 194         char                    *buf;
 195
 196         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 197                 bp->b_ops = NULL;
 198                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 199                 return;
 200         }
 201
 202         /*
 203          * As this symlink fits in an inode literal area, it must also fit in
 204          * the smallest buffer the filesystem supports.
 205          */
 206         ASSERT(BBTOB(bp->b_length) >=
 207                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 208
 209         bp->b_ops = &xfs_symlink_buf_ops;
 210
 211         buf = bp->b_addr;
 212         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 213         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 214 }
 215
 216 /* ----- Kernel only functions below ----- */
 217 STATIC int
 218 xfs_readlink_bmap(
 219         struct xfs_inode        *ip,
 220         char                    *link)
 221 {
 222         struct xfs_mount        *mp = ip->i_mount;
 223         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 224         struct xfs_buf          *bp;
 225         xfs_daddr_t             d;
 226         char                    *cur_chunk;
 227         int                     pathlen = ip->i_d.di_size;
 228         int                     nmaps = XFS_SYMLINK_MAPS;
 229         int                     byte_cnt;
 230         int                     n;
 231         int                     error = 0;
 232         int                     fsblocks = 0;
 233         int                     offset;
 234
 235         fsblocks = xfs_symlink_blocks(mp, pathlen);
 236         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
 237         if (error)
 238                 goto out;
 239
 240         offset = 0;
 241         for (n = 0; n < nmaps; n++) {
 242                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 243                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 244
 245                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
 246                                   &xfs_symlink_buf_ops);
 247                 if (!bp)
 248                         return XFS_ERROR(ENOMEM);
 249                 error = bp->b_error;
 250                 if (error) {
 251                         xfs_buf_ioerror_alert(bp, __func__);
 252                         xfs_buf_relse(bp);
 253                         goto out;
 254                 }
 255                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 256                 if (pathlen < byte_cnt)
 257                         byte_cnt = pathlen;
 258
 259                 cur_chunk = bp->b_addr;
 260                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
 261                         if (!xfs_symlink_hdr_ok(mp, ip->i_ino, offset,
 262                                                         byte_cnt, bp)) {
 263                                 error = EFSCORRUPTED;
 264                                 xfs_alert(mp,
 265 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
 266                                         offset, byte_cnt, ip->i_ino);
 267                                 xfs_buf_relse(bp);
 268                                 goto out;
 269
 270                         }
 271
 272                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 273                 }
 274
 275                 memcpy(link + offset, bp->b_addr, byte_cnt);
 276
 277                 pathlen -= byte_cnt;
 278                 offset += byte_cnt;
 279
 280                 xfs_buf_relse(bp);
 281         }
 282         ASSERT(pathlen == 0);
 283
 284         link[ip->i_d.di_size] = '\0';
 285         error = 0;
 286
 287  out:
 288         return error;
 289 }
 290
 291 int
 292 xfs_readlink(
 293         struct xfs_inode *ip,
 294         char            *link)
 295 {
 296         struct xfs_mount *mp = ip->i_mount;
 297         xfs_fsize_t     pathlen;
 298         int             error = 0;
 299
 300         trace_xfs_readlink(ip);
 301
 302         if (XFS_FORCED_SHUTDOWN(mp))
 303                 return XFS_ERROR(EIO);
 304
 305         xfs_ilock(ip, XFS_ILOCK_SHARED);
 306
 307         pathlen = ip->i_d.di_size;
 308         if (!pathlen)
 309                 goto out;
 310
 311         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 312                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 313                          __func__, (unsigned long long) ip->i_ino,
 314                          (long long) pathlen);
 315                 ASSERT(0);
 316                 error = XFS_ERROR(EFSCORRUPTED);
 317                 goto out;
 318         }
 319
 320
 321         if (ip->i_df.if_flags & XFS_IFINLINE) {
 322                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 323                 link[pathlen] = '\0';
 324         } else {
 325                 error = xfs_readlink_bmap(ip, link);
 326         }
 327
 328  out:
 329         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 330         return error;
 331 }
 332
 333 int
 334 xfs_symlink(
 335         struct xfs_inode        *dp,
 336         struct xfs_name         *link_name,
 337         const char              *target_path,
 338         umode_t                 mode,
 339         struct xfs_inode        **ipp)
 340 {
 341         struct xfs_mount        *mp = dp->i_mount;
 342         struct xfs_trans        *tp = NULL;
 343         struct xfs_inode        *ip = NULL;
 344         int                     error = 0;
 345         int                     pathlen;
 346         struct xfs_bmap_free    free_list;
 347         xfs_fsblock_t           first_block;
 348         bool                    unlock_dp_on_error = false;
 349         uint                    cancel_flags;
 350         int                     committed;
 351         xfs_fileoff_t           first_fsb;
 352         xfs_filblks_t           fs_blocks;
 353         int                     nmaps;
 354         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 355         xfs_daddr_t             d;
 356         const char              *cur_chunk;
 357         int                     byte_cnt;
 358         int                     n;
 359         xfs_buf_t               *bp;
 360         prid_t                  prid;
 361         struct xfs_dquot        *udqp = NULL;
 362         struct xfs_dquot        *gdqp = NULL;
 363         struct xfs_dquot        *pdqp = NULL;
 364         uint                    resblks;
 365
 366         *ipp = NULL;
 367
 368         trace_xfs_symlink(dp, link_name);
 369
 370         if (XFS_FORCED_SHUTDOWN(mp))
 371                 return XFS_ERROR(EIO);
 372
 373         /*
 374          * Check component lengths of the target path name.
 375          */
 376         pathlen = strlen(target_path);
 377         if (pathlen >= MAXPATHLEN)      /* total string too long */
 378                 return XFS_ERROR(ENAMETOOLONG);
 379
 380         udqp = gdqp = NULL;
 381         if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
 382                 prid = xfs_get_projid(dp);
 383         else
 384                 prid = XFS_PROJID_DEFAULT;
 385
 386         /*
 387          * Make sure that we have allocated dquot(s) on disk.
 388          */
 389         error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
 390                 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, &udqp, &gdqp, &pdqp);
 391         if (error)
 392                 goto std_return;
 393
 394         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 395         cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 396         /*
 397          * The symlink will fit into the inode data fork?
 398          * There can't be any attributes so we get the whole variable part.
 399          */
 400         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 401                 fs_blocks = 0;
 402         else
 403                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 404         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 405         error = xfs_trans_reserve(tp, resblks, XFS_SYMLINK_LOG_RES(mp), 0,
 406                         XFS_TRANS_PERM_LOG_RES, XFS_SYMLINK_LOG_COUNT);
 407         if (error == ENOSPC && fs_blocks == 0) {
 408                 resblks = 0;
 409                 error = xfs_trans_reserve(tp, 0, XFS_SYMLINK_LOG_RES(mp), 0,
 410                                 XFS_TRANS_PERM_LOG_RES, XFS_SYMLINK_LOG_COUNT);
 411         }
 412         if (error) {
 413                 cancel_flags = 0;
 414                 goto error_return;
 415         }
 416
 417         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 418         unlock_dp_on_error = true;
 419
 420         /*
 421          * Check whether the directory allows new symlinks or not.
 422          */
 423         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 424                 error = XFS_ERROR(EPERM);
 425                 goto error_return;
 426         }
 427
 428         /*
 429          * Reserve disk quota : blocks and inode.
 430          */
 431         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 432                                                 pdqp, resblks, 1, 0);
 433         if (error)
 434                 goto error_return;
 435
 436         /*
 437          * Check for ability to enter directory entry, if no space reserved.
 438          */
 439         error = xfs_dir_canenter(tp, dp, link_name, resblks);
 440         if (error)
 441                 goto error_return;
 442         /*
 443          * Initialize the bmap freelist prior to calling either
 444          * bmapi or the directory create code.
 445          */
 446         xfs_bmap_init(&free_list, &first_block);
 447
 448         /*
 449          * Allocate an inode for the symlink.
 450          */
 451         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 452                                prid, resblks > 0, &ip, NULL);
 453         if (error) {
 454                 if (error == ENOSPC)
 455                         goto error_return;
 456                 goto error1;
 457         }
 458
 459         /*
 460          * An error after we've joined dp to the transaction will result in the
 461          * transaction cancel unlocking dp so don't do it explicitly in the
 462          * error path.
 463          */
 464         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 465         unlock_dp_on_error = false;
 466
 467         /*
 468          * Also attach the dquot(s) to it, if applicable.
 469          */
 470         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 471
 472         if (resblks)
 473                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 474         /*
 475          * If the symlink will fit into the inode, write it inline.
 476          */
 477         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 478                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 479                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 480                 ip->i_d.di_size = pathlen;
 481
 482                 /*
 483                  * The inode was initially created in extent format.
 484                  */
 485                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 486                 ip->i_df.if_flags |= XFS_IFINLINE;
 487
 488                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 489                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 490
 491         } else {
 492                 int     offset;
 493
 494                 first_fsb = 0;
 495                 nmaps = XFS_SYMLINK_MAPS;
 496
 497                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 498                                   XFS_BMAPI_METADATA, &first_block, resblks,
 499                                   mval, &nmaps, &free_list);
 500                 if (error)
 501                         goto error2;
 502
 503                 if (resblks)
 504                         resblks -= fs_blocks;
 505                 ip->i_d.di_size = pathlen;
 506                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 507
 508                 cur_chunk = target_path;
 509                 offset = 0;
 510                 for (n = 0; n < nmaps; n++) {
 511                         char    *buf;
 512
 513                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 514                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 515                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 516                                                BTOBB(byte_cnt), 0);
 517                         if (!bp) {
 518                                 error = ENOMEM;
 519                                 goto error2;
 520                         }
 521                         bp->b_ops = &xfs_symlink_buf_ops;
 522
 523                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 524                         byte_cnt = min(byte_cnt, pathlen);
 525
 526                         buf = bp->b_addr;
 527                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 528                                                    byte_cnt, bp);
 529
 530                         memcpy(buf, cur_chunk, byte_cnt);
 531
 532                         cur_chunk += byte_cnt;
 533                         pathlen -= byte_cnt;
 534                         offset += byte_cnt;
 535
 536                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 537                                                         (char *)bp->b_addr);
 538                 }
 539                 ASSERT(pathlen == 0);
 540         }
 541
 542         /*
 543          * Create the directory entry for the symlink.
 544          */
 545         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 546                                         &first_block, &free_list, resblks);
 547         if (error)
 548                 goto error2;
 549         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 550         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 551
 552         /*
 553          * If this is a synchronous mount, make sure that the
 554          * symlink transaction goes to disk before returning to
 555          * the user.
 556          */
 557         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 558                 xfs_trans_set_sync(tp);
 559         }
 560
 561         error = xfs_bmap_finish(&tp, &free_list, &committed);
 562         if (error) {
 563                 goto error2;
 564         }
 565         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 566         xfs_qm_dqrele(udqp);
 567         xfs_qm_dqrele(gdqp);
 568         xfs_qm_dqrele(pdqp);
 569
 570         *ipp = ip;
 571         return 0;
 572
 573  error2:
 574         IRELE(ip);
 575  error1:
 576         xfs_bmap_cancel(&free_list);
 577         cancel_flags |= XFS_TRANS_ABORT;
 578  error_return:
 579         xfs_trans_cancel(tp, cancel_flags);
 580         xfs_qm_dqrele(udqp);
 581         xfs_qm_dqrele(gdqp);
 582         xfs_qm_dqrele(pdqp);
 583
 584         if (unlock_dp_on_error)
 585                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 586  std_return:
 587         return error;
 588 }
 589
 590 /*
 591  * Free a symlink that has blocks associated with it.
 592  */
 593 STATIC int
 594 xfs_inactive_symlink_rmt(
 595         xfs_inode_t     *ip,
 596         xfs_trans_t     **tpp)
 597 {
 598         xfs_buf_t       *bp;
 599         int             committed;
 600         int             done;
 601         int             error;
 602         xfs_fsblock_t   first_block;
 603         xfs_bmap_free_t free_list;
 604         int             i;
 605         xfs_mount_t     *mp;
 606         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 607         int             nmaps;
 608         xfs_trans_t     *ntp;
 609         int             size;
 610         xfs_trans_t     *tp;
 611
 612         tp = *tpp;
 613         mp = ip->i_mount;
 614         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 615         /*
 616          * We're freeing a symlink that has some
 617          * blocks allocated to it.  Free the
 618          * blocks here.  We know that we've got
 619          * either 1 or 2 extents and that we can
 620          * free them all in one bunmapi call.
 621          */
 622         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 623
 624         /*
 625          * Lock the inode, fix the size, and join it to the transaction.
 626          * Hold it so in the normal path, we still have it locked for
 627          * the second transaction.  In the error paths we need it
 628          * held so the cancel won't rele it, see below.
 629          */
 630         size = (int)ip->i_d.di_size;
 631         ip->i_d.di_size = 0;
 632         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 633         /*
 634          * Find the block(s) so we can inval and unmap them.
 635          */
 636         done = 0;
 637         xfs_bmap_init(&free_list, &first_block);
 638         nmaps = ARRAY_SIZE(mval);
 639         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 640                                 mval, &nmaps, 0);
 641         if (error)
 642                 goto error0;
 643         /*
 644          * Invalidate the block(s). No validation is done.
 645          */
 646         for (i = 0; i < nmaps; i++) {
 647                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 648                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 649                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 650                 if (!bp) {
 651                         error = ENOMEM;
 652                         goto error1;
 653                 }
 654                 xfs_trans_binval(tp, bp);
 655         }
 656         /*
 657          * Unmap the dead block(s) to the free_list.
 658          */
 659         if ((error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 660                         &first_block, &free_list, &done)))
 661                 goto error1;
 662         ASSERT(done);
 663         /*
 664          * Commit the first transaction.  This logs the EFI and the inode.
 665          */
 666         if ((error = xfs_bmap_finish(&tp, &free_list, &committed)))
 667                 goto error1;
 668         /*
 669          * The transaction must have been committed, since there were
 670          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 671          * The new tp has the extent freeing and EFDs.
 672          */
 673         ASSERT(committed);
 674         /*
 675          * The first xact was committed, so add the inode to the new one.
 676          * Mark it dirty so it will be logged and moved forward in the log as
 677          * part of every commit.
 678          */
 679         xfs_trans_ijoin(tp, ip, 0);
 680         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 681         /*
 682          * Get a new, empty transaction to return to our caller.
 683          */
 684         ntp = xfs_trans_dup(tp);
 685         /*
 686          * Commit the transaction containing extent freeing and EFDs.
 687          * If we get an error on the commit here or on the reserve below,
 688          * we need to unlock the inode since the new transaction doesn't
 689          * have the inode attached.
 690          */
 691         error = xfs_trans_commit(tp, 0);
 692         tp = ntp;
 693         if (error) {
 694                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 695                 goto error0;
 696         }
 697         /*
 698          * transaction commit worked ok so we can drop the extra ticket
 699          * reference that we gained in xfs_trans_dup()
 700          */
 701         xfs_log_ticket_put(tp->t_ticket);
 702
 703         /*
 704          * Remove the memory for extent descriptions (just bookkeeping).
 705          */
 706         if (ip->i_df.if_bytes)
 707                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 708         ASSERT(ip->i_df.if_bytes == 0);
 709         /*
 710          * Put an itruncate log reservation in the new transaction
 711          * for our caller.
 712          */
 713         if ((error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0,
 714                         XFS_TRANS_PERM_LOG_RES, XFS_ITRUNCATE_LOG_COUNT))) {
 715                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 716                 goto error0;
 717         }
 718
 719         xfs_trans_ijoin(tp, ip, 0);
 720         *tpp = tp;
 721         return 0;
 722
 723  error1:
 724         xfs_bmap_cancel(&free_list);
 725  error0:
 726         return error;
 727 }
 728
 729 /*
 730  * xfs_inactive_symlink - free a symlink
 731  */
 732 int
 733 xfs_inactive_symlink(
 734         struct xfs_inode        *ip,
 735         struct xfs_trans        **tp)
 736 {
 737         struct xfs_mount        *mp = ip->i_mount;
 738         int                     pathlen;
 739
 740         trace_xfs_inactive_symlink(ip);
 741
 742         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 743
 744         if (XFS_FORCED_SHUTDOWN(mp))
 745                 return XFS_ERROR(EIO);
 746
 747         /*
 748          * Zero length symlinks _can_ exist.
 749          */
 750         pathlen = (int)ip->i_d.di_size;
 751         if (!pathlen)
 752                 return 0;
 753
 754         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 755                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 756                          __func__, (unsigned long long)ip->i_ino, pathlen);
 757                 ASSERT(0);
 758                 return XFS_ERROR(EFSCORRUPTED);
 759         }
 760
 761         if (ip->i_df.if_flags & XFS_IFINLINE) {
 762                 if (ip->i_df.if_bytes > 0)
 763                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 764                                           XFS_DATA_FORK);
 765                 ASSERT(ip->i_df.if_bytes == 0);
 766                 return 0;
 767         }
 768
 769         /* remove the remote symlink */
 770         return xfs_inactive_symlink_rmt(ip, tp);
 771 }