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