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_da_btree.h"
  31 #include "xfs_dir2.h"
  32 #include "xfs_inode.h"
  33 #include "xfs_ialloc.h"
  34 #include "xfs_alloc.h"
  35 #include "xfs_bmap.h"
  36 #include "xfs_bmap_btree.h"
  37 #include "xfs_bmap_util.h"
  38 #include "xfs_error.h"
  39 #include "xfs_quota.h"
  40 #include "xfs_trans_space.h"
  41 #include "xfs_trace.h"
  42 #include "xfs_symlink.h"
  43 #include "xfs_trans.h"
  44 #include "xfs_log.h"
  45 #include "xfs_dinode.h"
  46
  47 /* ----- Kernel only functions below ----- */
  48 STATIC int
  49 xfs_readlink_bmap(
  50         struct xfs_inode        *ip,
  51         char                    *link)
  52 {
  53         struct xfs_mount        *mp = ip->i_mount;
  54         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
  55         struct xfs_buf          *bp;
  56         xfs_daddr_t             d;
  57         char                    *cur_chunk;
  58         int                     pathlen = ip->i_d.di_size;
  59         int                     nmaps = XFS_SYMLINK_MAPS;
  60         int                     byte_cnt;
  61         int                     n;
  62         int                     error = 0;
  63         int                     fsblocks = 0;
  64         int                     offset;
  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, bp->b_addr, 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         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         if (ip->i_df.if_flags & XFS_IFINLINE) {
 157                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 158                 link[pathlen] = '\0';
 159         } else {
 160                 error = xfs_readlink_bmap(ip, link);
 161         }
 162
 163  out:
 164         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 165         return error;
 166 }
 167
 168 int
 169 xfs_symlink(
 170         struct xfs_inode        *dp,
 171         struct xfs_name         *link_name,
 172         const char              *target_path,
 173         umode_t                 mode,
 174         struct xfs_inode        **ipp)
 175 {
 176         struct xfs_mount        *mp = dp->i_mount;
 177         struct xfs_trans        *tp = NULL;
 178         struct xfs_inode        *ip = NULL;
 179         int                     error = 0;
 180         int                     pathlen;
 181         struct xfs_bmap_free    free_list;
 182         xfs_fsblock_t           first_block;
 183         bool                    unlock_dp_on_error = false;
 184         uint                    cancel_flags;
 185         int                     committed;
 186         xfs_fileoff_t           first_fsb;
 187         xfs_filblks_t           fs_blocks;
 188         int                     nmaps;
 189         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 190         xfs_daddr_t             d;
 191         const char              *cur_chunk;
 192         int                     byte_cnt;
 193         int                     n;
 194         xfs_buf_t               *bp;
 195         prid_t                  prid;
 196         struct xfs_dquot        *udqp = NULL;
 197         struct xfs_dquot        *gdqp = NULL;
 198         struct xfs_dquot        *pdqp = NULL;
 199         uint                    resblks;
 200
 201         *ipp = NULL;
 202
 203         trace_xfs_symlink(dp, link_name);
 204
 205         if (XFS_FORCED_SHUTDOWN(mp))
 206                 return -EIO;
 207
 208         /*
 209          * Check component lengths of the target path name.
 210          */
 211         pathlen = strlen(target_path);
 212         if (pathlen >= MAXPATHLEN)      /* total string too long */
 213                 return -ENAMETOOLONG;
 214
 215         udqp = gdqp = NULL;
 216         prid = xfs_get_initial_prid(dp);
 217
 218         /*
 219          * Make sure that we have allocated dquot(s) on disk.
 220          */
 221         error = xfs_qm_vop_dqalloc(dp,
 222                         xfs_kuid_to_uid(current_fsuid()),
 223                         xfs_kgid_to_gid(current_fsgid()), prid,
 224                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 225                         &udqp, &gdqp, &pdqp);
 226         if (error)
 227                 goto std_return;
 228
 229         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 230         cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 231         /*
 232          * The symlink will fit into the inode data fork?
 233          * There can't be any attributes so we get the whole variable part.
 234          */
 235         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 236                 fs_blocks = 0;
 237         else
 238                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 239         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 240         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
 241         if (error == -ENOSPC && fs_blocks == 0) {
 242                 resblks = 0;
 243                 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
 244         }
 245         if (error) {
 246                 cancel_flags = 0;
 247                 goto error_return;
 248         }
 249
 250         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 251         unlock_dp_on_error = true;
 252
 253         /*
 254          * Check whether the directory allows new symlinks or not.
 255          */
 256         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 257                 error = -EPERM;
 258                 goto error_return;
 259         }
 260
 261         /*
 262          * Reserve disk quota : blocks and inode.
 263          */
 264         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 265                                                 pdqp, resblks, 1, 0);
 266         if (error)
 267                 goto error_return;
 268
 269         /*
 270          * Check for ability to enter directory entry, if no space reserved.
 271          */
 272         if (!resblks) {
 273                 error = xfs_dir_canenter(tp, dp, link_name);
 274                 if (error)
 275                         goto error_return;
 276         }
 277         /*
 278          * Initialize the bmap freelist prior to calling either
 279          * bmapi or the directory create code.
 280          */
 281         xfs_bmap_init(&free_list, &first_block);
 282
 283         /*
 284          * Allocate an inode for the symlink.
 285          */
 286         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 287                                prid, resblks > 0, &ip, NULL);
 288         if (error) {
 289                 if (error == -ENOSPC)
 290                         goto error_return;
 291                 goto error1;
 292         }
 293
 294         /*
 295          * An error after we've joined dp to the transaction will result in the
 296          * transaction cancel unlocking dp so don't do it explicitly in the
 297          * error path.
 298          */
 299         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 300         unlock_dp_on_error = false;
 301
 302         /*
 303          * Also attach the dquot(s) to it, if applicable.
 304          */
 305         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 306
 307         if (resblks)
 308                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 309         /*
 310          * If the symlink will fit into the inode, write it inline.
 311          */
 312         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 313                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 314                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 315                 ip->i_d.di_size = pathlen;
 316
 317                 /*
 318                  * The inode was initially created in extent format.
 319                  */
 320                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 321                 ip->i_df.if_flags |= XFS_IFINLINE;
 322
 323                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 324                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 325
 326         } else {
 327                 int     offset;
 328
 329                 first_fsb = 0;
 330                 nmaps = XFS_SYMLINK_MAPS;
 331
 332                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 333                                   XFS_BMAPI_METADATA, &first_block, resblks,
 334                                   mval, &nmaps, &free_list);
 335                 if (error)
 336                         goto error2;
 337
 338                 if (resblks)
 339                         resblks -= fs_blocks;
 340                 ip->i_d.di_size = pathlen;
 341                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 342
 343                 cur_chunk = target_path;
 344                 offset = 0;
 345                 for (n = 0; n < nmaps; n++) {
 346                         char    *buf;
 347
 348                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 349                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 350                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 351                                                BTOBB(byte_cnt), 0);
 352                         if (!bp) {
 353                                 error = -ENOMEM;
 354                                 goto error2;
 355                         }
 356                         bp->b_ops = &xfs_symlink_buf_ops;
 357
 358                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 359                         byte_cnt = min(byte_cnt, pathlen);
 360
 361                         buf = bp->b_addr;
 362                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 363                                                    byte_cnt, bp);
 364
 365                         memcpy(buf, cur_chunk, byte_cnt);
 366
 367                         cur_chunk += byte_cnt;
 368                         pathlen -= byte_cnt;
 369                         offset += byte_cnt;
 370
 371                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 372                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 373                                                         (char *)bp->b_addr);
 374                 }
 375                 ASSERT(pathlen == 0);
 376         }
 377
 378         /*
 379          * Create the directory entry for the symlink.
 380          */
 381         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 382                                         &first_block, &free_list, resblks);
 383         if (error)
 384                 goto error2;
 385         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 386         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 387
 388         /*
 389          * If this is a synchronous mount, make sure that the
 390          * symlink transaction goes to disk before returning to
 391          * the user.
 392          */
 393         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 394                 xfs_trans_set_sync(tp);
 395         }
 396
 397         error = xfs_bmap_finish(&tp, &free_list, &committed);
 398         if (error) {
 399                 goto error2;
 400         }
 401         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 402         xfs_qm_dqrele(udqp);
 403         xfs_qm_dqrele(gdqp);
 404         xfs_qm_dqrele(pdqp);
 405
 406         *ipp = ip;
 407         return 0;
 408
 409  error2:
 410         IRELE(ip);
 411  error1:
 412         xfs_bmap_cancel(&free_list);
 413         cancel_flags |= XFS_TRANS_ABORT;
 414  error_return:
 415         xfs_trans_cancel(tp, cancel_flags);
 416         xfs_qm_dqrele(udqp);
 417         xfs_qm_dqrele(gdqp);
 418         xfs_qm_dqrele(pdqp);
 419
 420         if (unlock_dp_on_error)
 421                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 422  std_return:
 423         return error;
 424 }
 425
 426 /*
 427  * Free a symlink that has blocks associated with it.
 428  */
 429 STATIC int
 430 xfs_inactive_symlink_rmt(
 431         struct xfs_inode *ip)
 432 {
 433         xfs_buf_t       *bp;
 434         int             committed;
 435         int             done;
 436         int             error;
 437         xfs_fsblock_t   first_block;
 438         xfs_bmap_free_t free_list;
 439         int             i;
 440         xfs_mount_t     *mp;
 441         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 442         int             nmaps;
 443         int             size;
 444         xfs_trans_t     *tp;
 445
 446         mp = ip->i_mount;
 447         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 448         /*
 449          * We're freeing a symlink that has some
 450          * blocks allocated to it.  Free the
 451          * blocks here.  We know that we've got
 452          * either 1 or 2 extents and that we can
 453          * free them all in one bunmapi call.
 454          */
 455         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 456
 457         tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
 458         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 459         if (error) {
 460                 xfs_trans_cancel(tp, 0);
 461                 return error;
 462         }
 463
 464         xfs_ilock(ip, XFS_ILOCK_EXCL);
 465         xfs_trans_ijoin(tp, ip, 0);
 466
 467         /*
 468          * Lock the inode, fix the size, and join it to the transaction.
 469          * Hold it so in the normal path, we still have it locked for
 470          * the second transaction.  In the error paths we need it
 471          * held so the cancel won't rele it, see below.
 472          */
 473         size = (int)ip->i_d.di_size;
 474         ip->i_d.di_size = 0;
 475         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 476         /*
 477          * Find the block(s) so we can inval and unmap them.
 478          */
 479         done = 0;
 480         xfs_bmap_init(&free_list, &first_block);
 481         nmaps = ARRAY_SIZE(mval);
 482         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 483                                 mval, &nmaps, 0);
 484         if (error)
 485                 goto error_trans_cancel;
 486         /*
 487          * Invalidate the block(s). No validation is done.
 488          */
 489         for (i = 0; i < nmaps; i++) {
 490                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 491                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 492                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 493                 if (!bp) {
 494                         error = -ENOMEM;
 495                         goto error_bmap_cancel;
 496                 }
 497                 xfs_trans_binval(tp, bp);
 498         }
 499         /*
 500          * Unmap the dead block(s) to the free_list.
 501          */
 502         error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 503                             &first_block, &free_list, &done);
 504         if (error)
 505                 goto error_bmap_cancel;
 506         ASSERT(done);
 507         /*
 508          * Commit the first transaction.  This logs the EFI and the inode.
 509          */
 510         error = xfs_bmap_finish(&tp, &free_list, &committed);
 511         if (error)
 512                 goto error_bmap_cancel;
 513         /*
 514          * The transaction must have been committed, since there were
 515          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 516          * The new tp has the extent freeing and EFDs.
 517          */
 518         ASSERT(committed);
 519         /*
 520          * The first xact was committed, so add the inode to the new one.
 521          * Mark it dirty so it will be logged and moved forward in the log as
 522          * part of every commit.
 523          */
 524         xfs_trans_ijoin(tp, ip, 0);
 525         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 526         /*
 527          * Commit the transaction containing extent freeing and EFDs.
 528          */
 529         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 530         if (error) {
 531                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 532                 goto error_unlock;
 533         }
 534
 535         /*
 536          * Remove the memory for extent descriptions (just bookkeeping).
 537          */
 538         if (ip->i_df.if_bytes)
 539                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 540         ASSERT(ip->i_df.if_bytes == 0);
 541
 542         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 543         return 0;
 544
 545 error_bmap_cancel:
 546         xfs_bmap_cancel(&free_list);
 547 error_trans_cancel:
 548         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 549 error_unlock:
 550         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 551         return error;
 552 }
 553
 554 /*
 555  * xfs_inactive_symlink - free a symlink
 556  */
 557 int
 558 xfs_inactive_symlink(
 559         struct xfs_inode        *ip)
 560 {
 561         struct xfs_mount        *mp = ip->i_mount;
 562         int                     pathlen;
 563
 564         trace_xfs_inactive_symlink(ip);
 565
 566         if (XFS_FORCED_SHUTDOWN(mp))
 567                 return -EIO;
 568
 569         xfs_ilock(ip, XFS_ILOCK_EXCL);
 570
 571         /*
 572          * Zero length symlinks _can_ exist.
 573          */
 574         pathlen = (int)ip->i_d.di_size;
 575         if (!pathlen) {
 576                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 577                 return 0;
 578         }
 579
 580         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 581                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 582                          __func__, (unsigned long long)ip->i_ino, pathlen);
 583                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 584                 ASSERT(0);
 585                 return -EFSCORRUPTED;
 586         }
 587
 588         if (ip->i_df.if_flags & XFS_IFINLINE) {
 589                 if (ip->i_df.if_bytes > 0)
 590                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 591                                           XFS_DATA_FORK);
 592                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 593                 ASSERT(ip->i_df.if_bytes == 0);
 594                 return 0;
 595         }
 596
 597         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 598
 599         /* remove the remote symlink */
 600         return xfs_inactive_symlink_rmt(ip);
 601 }