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