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_shared.h"
  21 #include "xfs_fs.h"
  22 #include "xfs_format.h"
  23 #include "xfs_log_format.h"
  24 #include "xfs_trans_resv.h"
  25 #include "xfs_bit.h"
  26 #include "xfs_sb.h"
  27 #include "xfs_ag.h"
  28 #include "xfs_mount.h"
  29 #include "xfs_da_format.h"
  30 #include "xfs_da_btree.h"
  31 #include "xfs_dir2.h"
  32 #include "xfs_inode.h"
  33 #include "xfs_ialloc.h"
  34 #include "xfs_alloc.h"
  35 #include "xfs_bmap.h"
  36 #include "xfs_bmap_btree.h"
  37 #include "xfs_bmap_util.h"
  38 #include "xfs_error.h"
  39 #include "xfs_quota.h"
  40 #include "xfs_trans_space.h"
  41 #include "xfs_trace.h"
  42 #include "xfs_symlink.h"
  43 #include "xfs_trans.h"
  44 #include "xfs_log.h"
  45 #include "xfs_dinode.h"
  46
  47 /* ----- Kernel only functions below ----- */
  48 STATIC int
  49 xfs_readlink_bmap(
  50         struct xfs_inode        *ip,
  51         char                    *link)
  52 {
  53         struct xfs_mount        *mp = ip->i_mount;
  54         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
  55         struct xfs_buf          *bp;
  56         xfs_daddr_t             d;
  57         char                    *cur_chunk;
  58         int                     pathlen = ip->i_d.di_size;
  59         int                     nmaps = XFS_SYMLINK_MAPS;
  60         int                     byte_cnt;
  61         int                     n;
  62         int                     error = 0;
  63         int                     fsblocks = 0;
  64         int                     offset;
  65
  66         fsblocks = xfs_symlink_blocks(mp, pathlen);
  67         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
  68         if (error)
  69                 goto out;
  70
  71         offset = 0;
  72         for (n = 0; n < nmaps; n++) {
  73                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
  74                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
  75
  76                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
  77                                   &xfs_symlink_buf_ops);
  78                 if (!bp)
  79                         return XFS_ERROR(ENOMEM);
  80                 error = bp->b_error;
  81                 if (error) {
  82                         xfs_buf_ioerror_alert(bp, __func__);
  83                         xfs_buf_relse(bp);
  84
  85                         /* bad CRC means corrupted metadata */
  86                         if (error == EFSBADCRC)
  87                                 error = EFSCORRUPTED;
  88                         goto out;
  89                 }
  90                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
  91                 if (pathlen < byte_cnt)
  92                         byte_cnt = pathlen;
  93
  94                 cur_chunk = bp->b_addr;
  95                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
  96                         if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
  97                                                         byte_cnt, bp)) {
  98                                 error = EFSCORRUPTED;
  99                                 xfs_alert(mp,
 100 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
 101                                         offset, byte_cnt, ip->i_ino);
 102                                 xfs_buf_relse(bp);
 103                                 goto out;
 104
 105                         }
 106
 107                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 108                 }
 109
 110                 memcpy(link + offset, bp->b_addr, byte_cnt);
 111
 112                 pathlen -= byte_cnt;
 113                 offset += byte_cnt;
 114
 115                 xfs_buf_relse(bp);
 116         }
 117         ASSERT(pathlen == 0);
 118
 119         link[ip->i_d.di_size] = '\0';
 120         error = 0;
 121
 122  out:
 123         return error;
 124 }
 125
 126 int
 127 xfs_readlink(
 128         struct xfs_inode *ip,
 129         char            *link)
 130 {
 131         struct xfs_mount *mp = ip->i_mount;
 132         xfs_fsize_t     pathlen;
 133         int             error = 0;
 134
 135         trace_xfs_readlink(ip);
 136
 137         if (XFS_FORCED_SHUTDOWN(mp))
 138                 return XFS_ERROR(EIO);
 139
 140         xfs_ilock(ip, XFS_ILOCK_SHARED);
 141
 142         pathlen = ip->i_d.di_size;
 143         if (!pathlen)
 144                 goto out;
 145
 146         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 147                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 148                          __func__, (unsigned long long) ip->i_ino,
 149                          (long long) pathlen);
 150                 ASSERT(0);
 151                 error = XFS_ERROR(EFSCORRUPTED);
 152                 goto out;
 153         }
 154
 155
 156         if (ip->i_df.if_flags & XFS_IFINLINE) {
 157                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 158                 link[pathlen] = '\0';
 159         } else {
 160                 error = xfs_readlink_bmap(ip, link);
 161         }
 162
 163  out:
 164         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 165         return error;
 166 }
 167
 168 int
 169 xfs_symlink(
 170         struct xfs_inode        *dp,
 171         struct xfs_name         *link_name,
 172         const char              *target_path,
 173         umode_t                 mode,
 174         struct xfs_inode        **ipp)
 175 {
 176         struct xfs_mount        *mp = dp->i_mount;
 177         struct xfs_trans        *tp = NULL;
 178         struct xfs_inode        *ip = NULL;
 179         int                     error = 0;
 180         int                     pathlen;
 181         struct xfs_bmap_free    free_list;
 182         xfs_fsblock_t           first_block;
 183         bool                    unlock_dp_on_error = false;
 184         uint                    cancel_flags;
 185         int                     committed;
 186         xfs_fileoff_t           first_fsb;
 187         xfs_filblks_t           fs_blocks;
 188         int                     nmaps;
 189         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 190         xfs_daddr_t             d;
 191         const char              *cur_chunk;
 192         int                     byte_cnt;
 193         int                     n;
 194         xfs_buf_t               *bp;
 195         prid_t                  prid;
 196         struct xfs_dquot        *udqp = NULL;
 197         struct xfs_dquot        *gdqp = NULL;
 198         struct xfs_dquot        *pdqp = NULL;
 199         uint                    resblks;
 200
 201         *ipp = NULL;
 202
 203         trace_xfs_symlink(dp, link_name);
 204
 205         if (XFS_FORCED_SHUTDOWN(mp))
 206                 return XFS_ERROR(EIO);
 207
 208         /*
 209          * Check component lengths of the target path name.
 210          */
 211         pathlen = strlen(target_path);
 212         if (pathlen >= MAXPATHLEN)      /* total string too long */
 213                 return XFS_ERROR(ENAMETOOLONG);
 214
 215         udqp = gdqp = NULL;
 216         prid = xfs_get_initial_prid(dp);
 217
 218         /*
 219          * Make sure that we have allocated dquot(s) on disk.
 220          */
 221         error = xfs_qm_vop_dqalloc(dp,
 222                         xfs_kuid_to_uid(current_fsuid()),
 223                         xfs_kgid_to_gid(current_fsgid()), prid,
 224                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 225                         &udqp, &gdqp, &pdqp);
 226         if (error)
 227                 goto std_return;
 228
 229         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 230         cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 231         /*
 232          * The symlink will fit into the inode data fork?
 233          * There can't be any attributes so we get the whole variable part.
 234          */
 235         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 236                 fs_blocks = 0;
 237         else
 238                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 239         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 240         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
 241         if (error == ENOSPC && fs_blocks == 0) {
 242                 resblks = 0;
 243                 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
 244         }
 245         if (error) {
 246                 cancel_flags = 0;
 247                 goto error_return;
 248         }
 249
 250         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 251         unlock_dp_on_error = true;
 252
 253         /*
 254          * Check whether the directory allows new symlinks or not.
 255          */
 256         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 257                 error = XFS_ERROR(EPERM);
 258                 goto error_return;
 259         }
 260
 261         /*
 262          * Reserve disk quota : blocks and inode.
 263          */
 264         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 265                                                 pdqp, resblks, 1, 0);
 266         if (error)
 267                 goto error_return;
 268
 269         /*
 270          * Check for ability to enter directory entry, if no space reserved.
 271          */
 272         error = xfs_dir_canenter(tp, dp, link_name, resblks);
 273         if (error)
 274                 goto error_return;
 275         /*
 276          * Initialize the bmap freelist prior to calling either
 277          * bmapi or the directory create code.
 278          */
 279         xfs_bmap_init(&free_list, &first_block);
 280
 281         /*
 282          * Allocate an inode for the symlink.
 283          */
 284         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 285                                prid, resblks > 0, &ip, NULL);
 286         if (error) {
 287                 if (error == ENOSPC)
 288                         goto error_return;
 289                 goto error1;
 290         }
 291
 292         /*
 293          * An error after we've joined dp to the transaction will result in the
 294          * transaction cancel unlocking dp so don't do it explicitly in the
 295          * error path.
 296          */
 297         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 298         unlock_dp_on_error = false;
 299
 300         /*
 301          * Also attach the dquot(s) to it, if applicable.
 302          */
 303         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 304
 305         if (resblks)
 306                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 307         /*
 308          * If the symlink will fit into the inode, write it inline.
 309          */
 310         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 311                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 312                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 313                 ip->i_d.di_size = pathlen;
 314
 315                 /*
 316                  * The inode was initially created in extent format.
 317                  */
 318                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 319                 ip->i_df.if_flags |= XFS_IFINLINE;
 320
 321                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 322                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 323
 324         } else {
 325                 int     offset;
 326
 327                 first_fsb = 0;
 328                 nmaps = XFS_SYMLINK_MAPS;
 329
 330                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 331                                   XFS_BMAPI_METADATA, &first_block, resblks,
 332                                   mval, &nmaps, &free_list);
 333                 if (error)
 334                         goto error2;
 335
 336                 if (resblks)
 337                         resblks -= fs_blocks;
 338                 ip->i_d.di_size = pathlen;
 339                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 340
 341                 cur_chunk = target_path;
 342                 offset = 0;
 343                 for (n = 0; n < nmaps; n++) {
 344                         char    *buf;
 345
 346                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 347                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 348                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 349                                                BTOBB(byte_cnt), 0);
 350                         if (!bp) {
 351                                 error = ENOMEM;
 352                                 goto error2;
 353                         }
 354                         bp->b_ops = &xfs_symlink_buf_ops;
 355
 356                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 357                         byte_cnt = min(byte_cnt, pathlen);
 358
 359                         buf = bp->b_addr;
 360                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 361                                                    byte_cnt, bp);
 362
 363                         memcpy(buf, cur_chunk, byte_cnt);
 364
 365                         cur_chunk += byte_cnt;
 366                         pathlen -= byte_cnt;
 367                         offset += byte_cnt;
 368
 369                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 370                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 371                                                         (char *)bp->b_addr);
 372                 }
 373                 ASSERT(pathlen == 0);
 374         }
 375
 376         /*
 377          * Create the directory entry for the symlink.
 378          */
 379         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 380                                         &first_block, &free_list, resblks);
 381         if (error)
 382                 goto error2;
 383         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 384         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 385
 386         /*
 387          * If this is a synchronous mount, make sure that the
 388          * symlink transaction goes to disk before returning to
 389          * the user.
 390          */
 391         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 392                 xfs_trans_set_sync(tp);
 393         }
 394
 395         error = xfs_bmap_finish(&tp, &free_list, &committed);
 396         if (error) {
 397                 goto error2;
 398         }
 399         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 400         xfs_qm_dqrele(udqp);
 401         xfs_qm_dqrele(gdqp);
 402         xfs_qm_dqrele(pdqp);
 403
 404         *ipp = ip;
 405         return 0;
 406
 407  error2:
 408         IRELE(ip);
 409  error1:
 410         xfs_bmap_cancel(&free_list);
 411         cancel_flags |= XFS_TRANS_ABORT;
 412  error_return:
 413         xfs_trans_cancel(tp, cancel_flags);
 414         xfs_qm_dqrele(udqp);
 415         xfs_qm_dqrele(gdqp);
 416         xfs_qm_dqrele(pdqp);
 417
 418         if (unlock_dp_on_error)
 419                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 420  std_return:
 421         return error;
 422 }
 423
 424 /*
 425  * Free a symlink that has blocks associated with it.
 426  */
 427 STATIC int
 428 xfs_inactive_symlink_rmt(
 429         struct xfs_inode *ip)
 430 {
 431         xfs_buf_t       *bp;
 432         int             committed;
 433         int             done;
 434         int             error;
 435         xfs_fsblock_t   first_block;
 436         xfs_bmap_free_t free_list;
 437         int             i;
 438         xfs_mount_t     *mp;
 439         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 440         int             nmaps;
 441         int             size;
 442         xfs_trans_t     *tp;
 443
 444         mp = ip->i_mount;
 445         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 446         /*
 447          * We're freeing a symlink that has some
 448          * blocks allocated to it.  Free the
 449          * blocks here.  We know that we've got
 450          * either 1 or 2 extents and that we can
 451          * free them all in one bunmapi call.
 452          */
 453         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 454
 455         tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
 456         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 457         if (error) {
 458                 xfs_trans_cancel(tp, 0);
 459                 return error;
 460         }
 461
 462         xfs_ilock(ip, XFS_ILOCK_EXCL);
 463         xfs_trans_ijoin(tp, ip, 0);
 464
 465         /*
 466          * Lock the inode, fix the size, and join it to the transaction.
 467          * Hold it so in the normal path, we still have it locked for
 468          * the second transaction.  In the error paths we need it
 469          * held so the cancel won't rele it, see below.
 470          */
 471         size = (int)ip->i_d.di_size;
 472         ip->i_d.di_size = 0;
 473         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 474         /*
 475          * Find the block(s) so we can inval and unmap them.
 476          */
 477         done = 0;
 478         xfs_bmap_init(&free_list, &first_block);
 479         nmaps = ARRAY_SIZE(mval);
 480         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 481                                 mval, &nmaps, 0);
 482         if (error)
 483                 goto error_trans_cancel;
 484         /*
 485          * Invalidate the block(s). No validation is done.
 486          */
 487         for (i = 0; i < nmaps; i++) {
 488                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 489                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 490                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 491                 if (!bp) {
 492                         error = ENOMEM;
 493                         goto error_bmap_cancel;
 494                 }
 495                 xfs_trans_binval(tp, bp);
 496         }
 497         /*
 498          * Unmap the dead block(s) to the free_list.
 499          */
 500         error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 501                             &first_block, &free_list, &done);
 502         if (error)
 503                 goto error_bmap_cancel;
 504         ASSERT(done);
 505         /*
 506          * Commit the first transaction.  This logs the EFI and the inode.
 507          */
 508         error = xfs_bmap_finish(&tp, &free_list, &committed);
 509         if (error)
 510                 goto error_bmap_cancel;
 511         /*
 512          * The transaction must have been committed, since there were
 513          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 514          * The new tp has the extent freeing and EFDs.
 515          */
 516         ASSERT(committed);
 517         /*
 518          * The first xact was committed, so add the inode to the new one.
 519          * Mark it dirty so it will be logged and moved forward in the log as
 520          * part of every commit.
 521          */
 522         xfs_trans_ijoin(tp, ip, 0);
 523         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 524         /*
 525          * Commit the transaction containing extent freeing and EFDs.
 526          */
 527         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 528         if (error) {
 529                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 530                 goto error_unlock;
 531         }
 532
 533         /*
 534          * Remove the memory for extent descriptions (just bookkeeping).
 535          */
 536         if (ip->i_df.if_bytes)
 537                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 538         ASSERT(ip->i_df.if_bytes == 0);
 539
 540         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 541         return 0;
 542
 543 error_bmap_cancel:
 544         xfs_bmap_cancel(&free_list);
 545 error_trans_cancel:
 546         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 547 error_unlock:
 548         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 549         return error;
 550 }
 551
 552 /*
 553  * xfs_inactive_symlink - free a symlink
 554  */
 555 int
 556 xfs_inactive_symlink(
 557         struct xfs_inode        *ip)
 558 {
 559         struct xfs_mount        *mp = ip->i_mount;
 560         int                     pathlen;
 561
 562         trace_xfs_inactive_symlink(ip);
 563
 564         if (XFS_FORCED_SHUTDOWN(mp))
 565                 return XFS_ERROR(EIO);
 566
 567         xfs_ilock(ip, XFS_ILOCK_EXCL);
 568
 569         /*
 570          * Zero length symlinks _can_ exist.
 571          */
 572         pathlen = (int)ip->i_d.di_size;
 573         if (!pathlen) {
 574                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 575                 return 0;
 576         }
 577
 578         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 579                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 580                          __func__, (unsigned long long)ip->i_ino, pathlen);
 581                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 582                 ASSERT(0);
 583                 return XFS_ERROR(EFSCORRUPTED);
 584         }
 585
 586         if (ip->i_df.if_flags & XFS_IFINLINE) {
 587                 if (ip->i_df.if_bytes > 0)
 588                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 589                                           XFS_DATA_FORK);
 590                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 591                 ASSERT(ip->i_df.if_bytes == 0);
 592                 return 0;
 593         }
 594
 595         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 596
 597         /* remove the remote symlink */
 598         return xfs_inactive_symlink_rmt(ip);
 599 }