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