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_dir2.h"
  30 #include "xfs_inode.h"
  31 #include "xfs_ialloc.h"
  32 #include "xfs_alloc.h"
  33 #include "xfs_bmap.h"
  34 #include "xfs_bmap_btree.h"
  35 #include "xfs_bmap_util.h"
  36 #include "xfs_error.h"
  37 #include "xfs_quota.h"
  38 #include "xfs_trans_space.h"
  39 #include "xfs_trace.h"
  40 #include "xfs_symlink.h"
  41 #include "xfs_trans.h"
  42 #include "xfs_log.h"
  43
  44 /* ----- Kernel only functions below ----- */
  45 STATIC int
  46 xfs_readlink_bmap(
  47         struct xfs_inode        *ip,
  48         char                    *link)
  49 {
  50         struct xfs_mount        *mp = ip->i_mount;
  51         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
  52         struct xfs_buf          *bp;
  53         xfs_daddr_t             d;
  54         char                    *cur_chunk;
  55         int                     pathlen = ip->i_d.di_size;
  56         int                     nmaps = XFS_SYMLINK_MAPS;
  57         int                     byte_cnt;
  58         int                     n;
  59         int                     error = 0;
  60         int                     fsblocks = 0;
  61         int                     offset;
  62
  63         fsblocks = xfs_symlink_blocks(mp, pathlen);
  64         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
  65         if (error)
  66                 goto out;
  67
  68         offset = 0;
  69         for (n = 0; n < nmaps; n++) {
  70                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
  71                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
  72
  73                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
  74                                   &xfs_symlink_buf_ops);
  75                 if (!bp)
  76                         return -ENOMEM;
  77                 error = bp->b_error;
  78                 if (error) {
  79                         xfs_buf_ioerror_alert(bp, __func__);
  80                         xfs_buf_relse(bp);
  81
  82                         /* bad CRC means corrupted metadata */
  83                         if (error == -EFSBADCRC)
  84                                 error = -EFSCORRUPTED;
  85                         goto out;
  86                 }
  87                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
  88                 if (pathlen < byte_cnt)
  89                         byte_cnt = pathlen;
  90
  91                 cur_chunk = bp->b_addr;
  92                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
  93                         if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
  94                                                         byte_cnt, bp)) {
  95                                 error = -EFSCORRUPTED;
  96                                 xfs_alert(mp,
  97 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
  98                                         offset, byte_cnt, ip->i_ino);
  99                                 xfs_buf_relse(bp);
 100                                 goto out;
 101
 102                         }
 103
 104                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 105                 }
 106
 107                 memcpy(link + offset, cur_chunk, byte_cnt);
 108
 109                 pathlen -= byte_cnt;
 110                 offset += byte_cnt;
 111
 112                 xfs_buf_relse(bp);
 113         }
 114         ASSERT(pathlen == 0);
 115
 116         link[ip->i_d.di_size] = '\0';
 117         error = 0;
 118
 119  out:
 120         return error;
 121 }
 122
 123 int
 124 xfs_readlink(
 125         struct xfs_inode *ip,
 126         char            *link)
 127 {
 128         struct xfs_mount *mp = ip->i_mount;
 129         xfs_fsize_t     pathlen;
 130         int             error = 0;
 131
 132         trace_xfs_readlink(ip);
 133
 134         if (XFS_FORCED_SHUTDOWN(mp))
 135                 return -EIO;
 136
 137         xfs_ilock(ip, XFS_ILOCK_SHARED);
 138
 139         pathlen = ip->i_d.di_size;
 140         if (!pathlen)
 141                 goto out;
 142
 143         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 144                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 145                          __func__, (unsigned long long) ip->i_ino,
 146                          (long long) pathlen);
 147                 ASSERT(0);
 148                 error = -EFSCORRUPTED;
 149                 goto out;
 150         }
 151
 152
 153         if (ip->i_df.if_flags & XFS_IFINLINE) {
 154                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 155                 link[pathlen] = '\0';
 156         } else {
 157                 error = xfs_readlink_bmap(ip, link);
 158         }
 159
 160  out:
 161         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 162         return error;
 163 }
 164
 165 int
 166 xfs_symlink(
 167         struct xfs_inode        *dp,
 168         struct xfs_name         *link_name,
 169         const char              *target_path,
 170         umode_t                 mode,
 171         struct xfs_inode        **ipp)
 172 {
 173         struct xfs_mount        *mp = dp->i_mount;
 174         struct xfs_trans        *tp = NULL;
 175         struct xfs_inode        *ip = NULL;
 176         int                     error = 0;
 177         int                     pathlen;
 178         struct xfs_bmap_free    free_list;
 179         xfs_fsblock_t           first_block;
 180         bool                    unlock_dp_on_error = false;
 181         xfs_fileoff_t           first_fsb;
 182         xfs_filblks_t           fs_blocks;
 183         int                     nmaps;
 184         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 185         xfs_daddr_t             d;
 186         const char              *cur_chunk;
 187         int                     byte_cnt;
 188         int                     n;
 189         xfs_buf_t               *bp;
 190         prid_t                  prid;
 191         struct xfs_dquot        *udqp = NULL;
 192         struct xfs_dquot        *gdqp = NULL;
 193         struct xfs_dquot        *pdqp = NULL;
 194         uint                    resblks;
 195
 196         *ipp = NULL;
 197
 198         trace_xfs_symlink(dp, link_name);
 199
 200         if (XFS_FORCED_SHUTDOWN(mp))
 201                 return -EIO;
 202
 203         /*
 204          * Check component lengths of the target path name.
 205          */
 206         pathlen = strlen(target_path);
 207         if (pathlen >= MAXPATHLEN)      /* total string too long */
 208                 return -ENAMETOOLONG;
 209
 210         udqp = gdqp = NULL;
 211         prid = xfs_get_initial_prid(dp);
 212
 213         /*
 214          * Make sure that we have allocated dquot(s) on disk.
 215          */
 216         error = xfs_qm_vop_dqalloc(dp,
 217                         xfs_kuid_to_uid(current_fsuid()),
 218                         xfs_kgid_to_gid(current_fsgid()), prid,
 219                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 220                         &udqp, &gdqp, &pdqp);
 221         if (error)
 222                 return error;
 223
 224         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 225         /*
 226          * The symlink will fit into the inode data fork?
 227          * There can't be any attributes so we get the whole variable part.
 228          */
 229         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 230                 fs_blocks = 0;
 231         else
 232                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 233         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 234         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
 235         if (error == -ENOSPC && fs_blocks == 0) {
 236                 resblks = 0;
 237                 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
 238         }
 239         if (error)
 240                 goto out_trans_cancel;
 241
 242         xfs_ilock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL |
 243                       XFS_IOLOCK_PARENT | XFS_ILOCK_PARENT);
 244         unlock_dp_on_error = true;
 245
 246         /*
 247          * Check whether the directory allows new symlinks or not.
 248          */
 249         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 250                 error = -EPERM;
 251                 goto out_trans_cancel;
 252         }
 253
 254         /*
 255          * Reserve disk quota : blocks and inode.
 256          */
 257         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 258                                                 pdqp, resblks, 1, 0);
 259         if (error)
 260                 goto out_trans_cancel;
 261
 262         /*
 263          * Check for ability to enter directory entry, if no space reserved.
 264          */
 265         if (!resblks) {
 266                 error = xfs_dir_canenter(tp, dp, link_name);
 267                 if (error)
 268                         goto out_trans_cancel;
 269         }
 270         /*
 271          * Initialize the bmap freelist prior to calling either
 272          * bmapi or the directory create code.
 273          */
 274         xfs_bmap_init(&free_list, &first_block);
 275
 276         /*
 277          * Allocate an inode for the symlink.
 278          */
 279         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 280                                prid, resblks > 0, &ip, NULL);
 281         if (error)
 282                 goto out_trans_cancel;
 283
 284         /*
 285          * Now we join the directory inode to the transaction.  We do not do it
 286          * earlier because xfs_dir_ialloc might commit the previous transaction
 287          * (and release all the locks).  An error from here on will result in
 288          * the transaction cancel unlocking dp so don't do it explicitly in the
 289          * error path.
 290          */
 291         xfs_trans_ijoin(tp, dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 292         unlock_dp_on_error = false;
 293
 294         /*
 295          * Also attach the dquot(s) to it, if applicable.
 296          */
 297         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 298
 299         if (resblks)
 300                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 301         /*
 302          * If the symlink will fit into the inode, write it inline.
 303          */
 304         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 305                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 306                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 307                 ip->i_d.di_size = pathlen;
 308
 309                 /*
 310                  * The inode was initially created in extent format.
 311                  */
 312                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 313                 ip->i_df.if_flags |= XFS_IFINLINE;
 314
 315                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 316                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 317
 318         } else {
 319                 int     offset;
 320
 321                 first_fsb = 0;
 322                 nmaps = XFS_SYMLINK_MAPS;
 323
 324                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 325                                   XFS_BMAPI_METADATA, &first_block, resblks,
 326                                   mval, &nmaps, &free_list);
 327                 if (error)
 328                         goto out_bmap_cancel;
 329
 330                 if (resblks)
 331                         resblks -= fs_blocks;
 332                 ip->i_d.di_size = pathlen;
 333                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 334
 335                 cur_chunk = target_path;
 336                 offset = 0;
 337                 for (n = 0; n < nmaps; n++) {
 338                         char    *buf;
 339
 340                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 341                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 342                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 343                                                BTOBB(byte_cnt), 0);
 344                         if (!bp) {
 345                                 error = -ENOMEM;
 346                                 goto out_bmap_cancel;
 347                         }
 348                         bp->b_ops = &xfs_symlink_buf_ops;
 349
 350                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 351                         byte_cnt = min(byte_cnt, pathlen);
 352
 353                         buf = bp->b_addr;
 354                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 355                                                    byte_cnt, bp);
 356
 357                         memcpy(buf, cur_chunk, byte_cnt);
 358
 359                         cur_chunk += byte_cnt;
 360                         pathlen -= byte_cnt;
 361                         offset += byte_cnt;
 362
 363                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 364                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 365                                                         (char *)bp->b_addr);
 366                 }
 367                 ASSERT(pathlen == 0);
 368         }
 369
 370         /*
 371          * Create the directory entry for the symlink.
 372          */
 373         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 374                                         &first_block, &free_list, resblks);
 375         if (error)
 376                 goto out_bmap_cancel;
 377         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 378         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 379
 380         /*
 381          * If this is a synchronous mount, make sure that the
 382          * symlink transaction goes to disk before returning to
 383          * the user.
 384          */
 385         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 386                 xfs_trans_set_sync(tp);
 387         }
 388
 389         error = xfs_bmap_finish(&tp, &free_list, NULL);
 390         if (error)
 391                 goto out_bmap_cancel;
 392
 393         error = xfs_trans_commit(tp);
 394         if (error)
 395                 goto out_release_inode;
 396
 397         xfs_qm_dqrele(udqp);
 398         xfs_qm_dqrele(gdqp);
 399         xfs_qm_dqrele(pdqp);
 400
 401         *ipp = ip;
 402         return 0;
 403
 404 out_bmap_cancel:
 405         xfs_bmap_cancel(&free_list);
 406 out_trans_cancel:
 407         xfs_trans_cancel(tp);
 408 out_release_inode:
 409         /*
 410          * Wait until after the current transaction is aborted to finish the
 411          * setup of the inode and release the inode.  This prevents recursive
 412          * transactions and deadlocks from xfs_inactive.
 413          */
 414         if (ip) {
 415                 xfs_finish_inode_setup(ip);
 416                 IRELE(ip);
 417         }
 418
 419         xfs_qm_dqrele(udqp);
 420         xfs_qm_dqrele(gdqp);
 421         xfs_qm_dqrele(pdqp);
 422
 423         if (unlock_dp_on_error)
 424                 xfs_iunlock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 425         return error;
 426 }
 427
 428 /*
 429  * Free a symlink that has blocks associated with it.
 430  */
 431 STATIC int
 432 xfs_inactive_symlink_rmt(
 433         struct xfs_inode *ip)
 434 {
 435         xfs_buf_t       *bp;
 436         int             done;
 437         int             error;
 438         xfs_fsblock_t   first_block;
 439         xfs_bmap_free_t free_list;
 440         int             i;
 441         xfs_mount_t     *mp;
 442         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 443         int             nmaps;
 444         int             size;
 445         xfs_trans_t     *tp;
 446
 447         mp = ip->i_mount;
 448         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 449         /*
 450          * We're freeing a symlink that has some
 451          * blocks allocated to it.  Free the
 452          * blocks here.  We know that we've got
 453          * either 1 or 2 extents and that we can
 454          * free them all in one bunmapi call.
 455          */
 456         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 457
 458         tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
 459         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 460         if (error) {
 461                 xfs_trans_cancel(tp);
 462                 return error;
 463         }
 464
 465         xfs_ilock(ip, XFS_ILOCK_EXCL);
 466         xfs_trans_ijoin(tp, ip, 0);
 467
 468         /*
 469          * Lock the inode, fix the size, and join it to the transaction.
 470          * Hold it so in the normal path, we still have it locked for
 471          * the second transaction.  In the error paths we need it
 472          * held so the cancel won't rele it, see below.
 473          */
 474         size = (int)ip->i_d.di_size;
 475         ip->i_d.di_size = 0;
 476         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 477         /*
 478          * Find the block(s) so we can inval and unmap them.
 479          */
 480         done = 0;
 481         xfs_bmap_init(&free_list, &first_block);
 482         nmaps = ARRAY_SIZE(mval);
 483         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 484                                 mval, &nmaps, 0);
 485         if (error)
 486                 goto error_trans_cancel;
 487         /*
 488          * Invalidate the block(s). No validation is done.
 489          */
 490         for (i = 0; i < nmaps; i++) {
 491                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 492                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 493                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 494                 if (!bp) {
 495                         error = -ENOMEM;
 496                         goto error_bmap_cancel;
 497                 }
 498                 xfs_trans_binval(tp, bp);
 499         }
 500         /*
 501          * Unmap the dead block(s) to the free_list.
 502          */
 503         error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps,
 504                             &first_block, &free_list, &done);
 505         if (error)
 506                 goto error_bmap_cancel;
 507         ASSERT(done);
 508         /*
 509          * Commit the first transaction.  This logs the EFI and the inode.
 510          */
 511         error = xfs_bmap_finish(&tp, &free_list, ip);
 512         if (error)
 513                 goto error_bmap_cancel;
 514         /*
 515          * The first xact was committed, so add the inode to the new one.
 516          * Mark it dirty so it will be logged and moved forward in the log as
 517          * part of every commit.
 518          */
 519         xfs_trans_ijoin(tp, ip, 0);
 520         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 521         /*
 522          * Commit the transaction containing extent freeing and EFDs.
 523          */
 524         error = xfs_trans_commit(tp);
 525         if (error) {
 526                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 527                 goto error_unlock;
 528         }
 529
 530         /*
 531          * Remove the memory for extent descriptions (just bookkeeping).
 532          */
 533         if (ip->i_df.if_bytes)
 534                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 535         ASSERT(ip->i_df.if_bytes == 0);
 536
 537         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 538         return 0;
 539
 540 error_bmap_cancel:
 541         xfs_bmap_cancel(&free_list);
 542 error_trans_cancel:
 543         xfs_trans_cancel(tp);
 544 error_unlock:
 545         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 546         return error;
 547 }
 548
 549 /*
 550  * xfs_inactive_symlink - free a symlink
 551  */
 552 int
 553 xfs_inactive_symlink(
 554         struct xfs_inode        *ip)
 555 {
 556         struct xfs_mount        *mp = ip->i_mount;
 557         int                     pathlen;
 558
 559         trace_xfs_inactive_symlink(ip);
 560
 561         if (XFS_FORCED_SHUTDOWN(mp))
 562                 return -EIO;
 563
 564         xfs_ilock(ip, XFS_ILOCK_EXCL);
 565
 566         /*
 567          * Zero length symlinks _can_ exist.
 568          */
 569         pathlen = (int)ip->i_d.di_size;
 570         if (!pathlen) {
 571                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 572                 return 0;
 573         }
 574
 575         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 576                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 577                          __func__, (unsigned long long)ip->i_ino, pathlen);
 578                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 579                 ASSERT(0);
 580                 return -EFSCORRUPTED;
 581         }
 582
 583         if (ip->i_df.if_flags & XFS_IFINLINE) {
 584                 if (ip->i_df.if_bytes > 0)
 585                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 586                                           XFS_DATA_FORK);
 587                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 588                 ASSERT(ip->i_df.if_bytes == 0);
 589                 return 0;
 590         }
 591
 592         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 593
 594         /* remove the remote symlink */
 595         return xfs_inactive_symlink_rmt(ip);
 596 }