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_fs.h"
  21 #include "xfs_format.h"
  22 #include "xfs_bit.h"
  23 #include "xfs_log.h"
  24 #include "xfs_trans.h"
  25 #include "xfs_sb.h"
  26 #include "xfs_ag.h"
  27 #include "xfs_mount.h"
  28 #include "xfs_da_btree.h"
  29 #include "xfs_dir2_format.h"
  30 #include "xfs_dir2.h"
  31 #include "xfs_bmap_btree.h"
  32 #include "xfs_ialloc_btree.h"
  33 #include "xfs_dinode.h"
  34 #include "xfs_inode.h"
  35 #include "xfs_ialloc.h"
  36 #include "xfs_alloc.h"
  37 #include "xfs_bmap.h"
  38 #include "xfs_bmap_util.h"
  39 #include "xfs_error.h"
  40 #include "xfs_quota.h"
  41 #include "xfs_trans_space.h"
  42 #include "xfs_trace.h"
  43 #include "xfs_symlink.h"
  44
  45 /* ----- Kernel only functions below ----- */
  46 STATIC int
  47 xfs_readlink_bmap(
  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         fsblocks = xfs_symlink_blocks(mp, pathlen);
  65         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
  66         if (error)
  67                 goto out;
  68
  69         offset = 0;
  70         for (n = 0; n < nmaps; n++) {
  71                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
  72                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
  73
  74                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
  75                                   &xfs_symlink_buf_ops);
  76                 if (!bp)
  77                         return XFS_ERROR(ENOMEM);
  78                 error = bp->b_error;
  79                 if (error) {
  80                         xfs_buf_ioerror_alert(bp, __func__);
  81                         xfs_buf_relse(bp);
  82                         goto out;
  83                 }
  84                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
  85                 if (pathlen < byte_cnt)
  86                         byte_cnt = pathlen;
  87
  88                 cur_chunk = bp->b_addr;
  89                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
  90                         if (!xfs_symlink_hdr_ok(mp, ip->i_ino, offset,
  91                                                         byte_cnt, bp)) {
  92                                 error = EFSCORRUPTED;
  93                                 xfs_alert(mp,
  94 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
  95                                         offset, byte_cnt, ip->i_ino);
  96                                 xfs_buf_relse(bp);
  97                                 goto out;
  98
  99                         }
 100
 101                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 102                 }
 103
 104                 memcpy(link + offset, bp->b_addr, byte_cnt);
 105
 106                 pathlen -= byte_cnt;
 107                 offset += byte_cnt;
 108
 109                 xfs_buf_relse(bp);
 110         }
 111         ASSERT(pathlen == 0);
 112
 113         link[ip->i_d.di_size] = '\0';
 114         error = 0;
 115
 116  out:
 117         return error;
 118 }
 119
 120 int
 121 xfs_readlink(
 122         struct xfs_inode *ip,
 123         char            *link)
 124 {
 125         struct xfs_mount *mp = ip->i_mount;
 126         xfs_fsize_t     pathlen;
 127         int             error = 0;
 128
 129         trace_xfs_readlink(ip);
 130
 131         if (XFS_FORCED_SHUTDOWN(mp))
 132                 return XFS_ERROR(EIO);
 133
 134         xfs_ilock(ip, XFS_ILOCK_SHARED);
 135
 136         pathlen = ip->i_d.di_size;
 137         if (!pathlen)
 138                 goto out;
 139
 140         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 141                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 142                          __func__, (unsigned long long) ip->i_ino,
 143                          (long long) pathlen);
 144                 ASSERT(0);
 145                 error = XFS_ERROR(EFSCORRUPTED);
 146                 goto out;
 147         }
 148
 149
 150         if (ip->i_df.if_flags & XFS_IFINLINE) {
 151                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 152                 link[pathlen] = '\0';
 153         } else {
 154                 error = xfs_readlink_bmap(ip, link);
 155         }
 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         uint                    cancel_flags;
 179         int                     committed;
 180         xfs_fileoff_t           first_fsb;
 181         xfs_filblks_t           fs_blocks;
 182         int                     nmaps;
 183         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 184         xfs_daddr_t             d;
 185         const char              *cur_chunk;
 186         int                     byte_cnt;
 187         int                     n;
 188         xfs_buf_t               *bp;
 189         prid_t                  prid;
 190         struct xfs_dquot        *udqp = NULL;
 191         struct xfs_dquot        *gdqp = NULL;
 192         struct xfs_dquot        *pdqp = NULL;
 193         uint                    resblks;
 194
 195         *ipp = NULL;
 196
 197         trace_xfs_symlink(dp, link_name);
 198
 199         if (XFS_FORCED_SHUTDOWN(mp))
 200                 return XFS_ERROR(EIO);
 201
 202         /*
 203          * Check component lengths of the target path name.
 204          */
 205         pathlen = strlen(target_path);
 206         if (pathlen >= MAXPATHLEN)      /* total string too long */
 207                 return XFS_ERROR(ENAMETOOLONG);
 208
 209         udqp = gdqp = NULL;
 210         if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
 211                 prid = xfs_get_projid(dp);
 212         else
 213                 prid = XFS_PROJID_DEFAULT;
 214
 215         /*
 216          * Make sure that we have allocated dquot(s) on disk.
 217          */
 218         error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
 219                 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, &udqp, &gdqp, &pdqp);
 220         if (error)
 221                 goto std_return;
 222
 223         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 224         cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 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                 cancel_flags = 0;
 241                 goto error_return;
 242         }
 243
 244         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 245         unlock_dp_on_error = true;
 246
 247         /*
 248          * Check whether the directory allows new symlinks or not.
 249          */
 250         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 251                 error = XFS_ERROR(EPERM);
 252                 goto error_return;
 253         }
 254
 255         /*
 256          * Reserve disk quota : blocks and inode.
 257          */
 258         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 259                                                 pdqp, resblks, 1, 0);
 260         if (error)
 261                 goto error_return;
 262
 263         /*
 264          * Check for ability to enter directory entry, if no space reserved.
 265          */
 266         error = xfs_dir_canenter(tp, dp, link_name, resblks);
 267         if (error)
 268                 goto error_return;
 269         /*
 270          * Initialize the bmap freelist prior to calling either
 271          * bmapi or the directory create code.
 272          */
 273         xfs_bmap_init(&free_list, &first_block);
 274
 275         /*
 276          * Allocate an inode for the symlink.
 277          */
 278         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 279                                prid, resblks > 0, &ip, NULL);
 280         if (error) {
 281                 if (error == ENOSPC)
 282                         goto error_return;
 283                 goto error1;
 284         }
 285
 286         /*
 287          * An error after we've joined dp to the transaction will result in the
 288          * transaction cancel unlocking dp so don't do it explicitly in the
 289          * error path.
 290          */
 291         xfs_trans_ijoin(tp, dp, 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 error2;
 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 error2;
 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_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 364                                                         (char *)bp->b_addr);
 365                 }
 366                 ASSERT(pathlen == 0);
 367         }
 368
 369         /*
 370          * Create the directory entry for the symlink.
 371          */
 372         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 373                                         &first_block, &free_list, resblks);
 374         if (error)
 375                 goto error2;
 376         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 377         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 378
 379         /*
 380          * If this is a synchronous mount, make sure that the
 381          * symlink transaction goes to disk before returning to
 382          * the user.
 383          */
 384         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 385                 xfs_trans_set_sync(tp);
 386         }
 387
 388         error = xfs_bmap_finish(&tp, &free_list, &committed);
 389         if (error) {
 390                 goto error2;
 391         }
 392         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 393         xfs_qm_dqrele(udqp);
 394         xfs_qm_dqrele(gdqp);
 395         xfs_qm_dqrele(pdqp);
 396
 397         *ipp = ip;
 398         return 0;
 399
 400  error2:
 401         IRELE(ip);
 402  error1:
 403         xfs_bmap_cancel(&free_list);
 404         cancel_flags |= XFS_TRANS_ABORT;
 405  error_return:
 406         xfs_trans_cancel(tp, cancel_flags);
 407         xfs_qm_dqrele(udqp);
 408         xfs_qm_dqrele(gdqp);
 409         xfs_qm_dqrele(pdqp);
 410
 411         if (unlock_dp_on_error)
 412                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 413  std_return:
 414         return error;
 415 }
 416
 417 /*
 418  * Free a symlink that has blocks associated with it.
 419  */
 420 STATIC int
 421 xfs_inactive_symlink_rmt(
 422         xfs_inode_t     *ip,
 423         xfs_trans_t     **tpp)
 424 {
 425         xfs_buf_t       *bp;
 426         int             committed;
 427         int             done;
 428         int             error;
 429         xfs_fsblock_t   first_block;
 430         xfs_bmap_free_t free_list;
 431         int             i;
 432         xfs_mount_t     *mp;
 433         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 434         int             nmaps;
 435         xfs_trans_t     *ntp;
 436         int             size;
 437         xfs_trans_t     *tp;
 438
 439         tp = *tpp;
 440         mp = ip->i_mount;
 441         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 442         /*
 443          * We're freeing a symlink that has some
 444          * blocks allocated to it.  Free the
 445          * blocks here.  We know that we've got
 446          * either 1 or 2 extents and that we can
 447          * free them all in one bunmapi call.
 448          */
 449         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 450
 451         /*
 452          * Lock the inode, fix the size, and join it to the transaction.
 453          * Hold it so in the normal path, we still have it locked for
 454          * the second transaction.  In the error paths we need it
 455          * held so the cancel won't rele it, see below.
 456          */
 457         size = (int)ip->i_d.di_size;
 458         ip->i_d.di_size = 0;
 459         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 460         /*
 461          * Find the block(s) so we can inval and unmap them.
 462          */
 463         done = 0;
 464         xfs_bmap_init(&free_list, &first_block);
 465         nmaps = ARRAY_SIZE(mval);
 466         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 467                                 mval, &nmaps, 0);
 468         if (error)
 469                 goto error0;
 470         /*
 471          * Invalidate the block(s). No validation is done.
 472          */
 473         for (i = 0; i < nmaps; i++) {
 474                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 475                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 476                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 477                 if (!bp) {
 478                         error = ENOMEM;
 479                         goto error1;
 480                 }
 481                 xfs_trans_binval(tp, bp);
 482         }
 483         /*
 484          * Unmap the dead block(s) to the free_list.
 485          */
 486         if ((error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 487                         &first_block, &free_list, &done)))
 488                 goto error1;
 489         ASSERT(done);
 490         /*
 491          * Commit the first transaction.  This logs the EFI and the inode.
 492          */
 493         if ((error = xfs_bmap_finish(&tp, &free_list, &committed)))
 494                 goto error1;
 495         /*
 496          * The transaction must have been committed, since there were
 497          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 498          * The new tp has the extent freeing and EFDs.
 499          */
 500         ASSERT(committed);
 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          * Get a new, empty transaction to return to our caller.
 510          */
 511         ntp = xfs_trans_dup(tp);
 512         /*
 513          * Commit the transaction containing extent freeing and EFDs.
 514          * If we get an error on the commit here or on the reserve below,
 515          * we need to unlock the inode since the new transaction doesn't
 516          * have the inode attached.
 517          */
 518         error = xfs_trans_commit(tp, 0);
 519         tp = ntp;
 520         if (error) {
 521                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 522                 goto error0;
 523         }
 524         /*
 525          * transaction commit worked ok so we can drop the extra ticket
 526          * reference that we gained in xfs_trans_dup()
 527          */
 528         xfs_log_ticket_put(tp->t_ticket);
 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          * Put an itruncate log reservation in the new transaction
 538          * for our caller.
 539          */
 540         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 541         if (error) {
 542                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 543                 goto error0;
 544         }
 545
 546         xfs_trans_ijoin(tp, ip, 0);
 547         *tpp = tp;
 548         return 0;
 549
 550  error1:
 551         xfs_bmap_cancel(&free_list);
 552  error0:
 553         return error;
 554 }
 555
 556 /*
 557  * xfs_inactive_symlink - free a symlink
 558  */
 559 int
 560 xfs_inactive_symlink(
 561         struct xfs_inode        *ip,
 562         struct xfs_trans        **tp)
 563 {
 564         struct xfs_mount        *mp = ip->i_mount;
 565         int                     pathlen;
 566
 567         trace_xfs_inactive_symlink(ip);
 568
 569         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 570
 571         if (XFS_FORCED_SHUTDOWN(mp))
 572                 return XFS_ERROR(EIO);
 573
 574         /*
 575          * Zero length symlinks _can_ exist.
 576          */
 577         pathlen = (int)ip->i_d.di_size;
 578         if (!pathlen)
 579                 return 0;
 580
 581         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 582                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 583                          __func__, (unsigned long long)ip->i_ino, pathlen);
 584                 ASSERT(0);
 585                 return XFS_ERROR(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                 ASSERT(ip->i_df.if_bytes == 0);
 593                 return 0;
 594         }
 595
 596         /* remove the remote symlink */
 597         return xfs_inactive_symlink_rmt(ip, tp);
 598 }