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