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, resblks, XFS_SYMLINK_LOG_RES(mp), 0,
 235                         XFS_TRANS_PERM_LOG_RES, XFS_SYMLINK_LOG_COUNT);
 236         if (error == ENOSPC && fs_blocks == 0) {
 237                 resblks = 0;
 238                 error = xfs_trans_reserve(tp, 0, XFS_SYMLINK_LOG_RES(mp), 0,
 239                                 XFS_TRANS_PERM_LOG_RES, XFS_SYMLINK_LOG_COUNT);
 240         }
 241         if (error) {
 242                 cancel_flags = 0;
 243                 goto error_return;
 244         }
 245
 246         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 247         unlock_dp_on_error = true;
 248
 249         /*
 250          * Check whether the directory allows new symlinks or not.
 251          */
 252         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 253                 error = XFS_ERROR(EPERM);
 254                 goto error_return;
 255         }
 256
 257         /*
 258          * Reserve disk quota : blocks and inode.
 259          */
 260         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 261                                                 pdqp, resblks, 1, 0);
 262         if (error)
 263                 goto error_return;
 264
 265         /*
 266          * Check for ability to enter directory entry, if no space reserved.
 267          */
 268         error = xfs_dir_canenter(tp, dp, link_name, resblks);
 269         if (error)
 270                 goto error_return;
 271         /*
 272          * Initialize the bmap freelist prior to calling either
 273          * bmapi or the directory create code.
 274          */
 275         xfs_bmap_init(&free_list, &first_block);
 276
 277         /*
 278          * Allocate an inode for the symlink.
 279          */
 280         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 281                                prid, resblks > 0, &ip, NULL);
 282         if (error) {
 283                 if (error == ENOSPC)
 284                         goto error_return;
 285                 goto error1;
 286         }
 287
 288         /*
 289          * An error after we've joined dp to the transaction will result in the
 290          * transaction cancel unlocking dp so don't do it explicitly in the
 291          * error path.
 292          */
 293         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 294         unlock_dp_on_error = false;
 295
 296         /*
 297          * Also attach the dquot(s) to it, if applicable.
 298          */
 299         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 300
 301         if (resblks)
 302                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 303         /*
 304          * If the symlink will fit into the inode, write it inline.
 305          */
 306         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 307                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 308                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 309                 ip->i_d.di_size = pathlen;
 310
 311                 /*
 312                  * The inode was initially created in extent format.
 313                  */
 314                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 315                 ip->i_df.if_flags |= XFS_IFINLINE;
 316
 317                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 318                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 319
 320         } else {
 321                 int     offset;
 322
 323                 first_fsb = 0;
 324                 nmaps = XFS_SYMLINK_MAPS;
 325
 326                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 327                                   XFS_BMAPI_METADATA, &first_block, resblks,
 328                                   mval, &nmaps, &free_list);
 329                 if (error)
 330                         goto error2;
 331
 332                 if (resblks)
 333                         resblks -= fs_blocks;
 334                 ip->i_d.di_size = pathlen;
 335                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 336
 337                 cur_chunk = target_path;
 338                 offset = 0;
 339                 for (n = 0; n < nmaps; n++) {
 340                         char    *buf;
 341
 342                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 343                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 344                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 345                                                BTOBB(byte_cnt), 0);
 346                         if (!bp) {
 347                                 error = ENOMEM;
 348                                 goto error2;
 349                         }
 350                         bp->b_ops = &xfs_symlink_buf_ops;
 351
 352                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 353                         byte_cnt = min(byte_cnt, pathlen);
 354
 355                         buf = bp->b_addr;
 356                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 357                                                    byte_cnt, bp);
 358
 359                         memcpy(buf, cur_chunk, byte_cnt);
 360
 361                         cur_chunk += byte_cnt;
 362                         pathlen -= byte_cnt;
 363                         offset += byte_cnt;
 364
 365                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 366                                                         (char *)bp->b_addr);
 367                 }
 368                 ASSERT(pathlen == 0);
 369         }
 370
 371         /*
 372          * Create the directory entry for the symlink.
 373          */
 374         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 375                                         &first_block, &free_list, resblks);
 376         if (error)
 377                 goto error2;
 378         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 379         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 380
 381         /*
 382          * If this is a synchronous mount, make sure that the
 383          * symlink transaction goes to disk before returning to
 384          * the user.
 385          */
 386         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 387                 xfs_trans_set_sync(tp);
 388         }
 389
 390         error = xfs_bmap_finish(&tp, &free_list, &committed);
 391         if (error) {
 392                 goto error2;
 393         }
 394         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 395         xfs_qm_dqrele(udqp);
 396         xfs_qm_dqrele(gdqp);
 397         xfs_qm_dqrele(pdqp);
 398
 399         *ipp = ip;
 400         return 0;
 401
 402  error2:
 403         IRELE(ip);
 404  error1:
 405         xfs_bmap_cancel(&free_list);
 406         cancel_flags |= XFS_TRANS_ABORT;
 407  error_return:
 408         xfs_trans_cancel(tp, cancel_flags);
 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_ILOCK_EXCL);
 415  std_return:
 416         return error;
 417 }
 418
 419 /*
 420  * Free a symlink that has blocks associated with it.
 421  */
 422 STATIC int
 423 xfs_inactive_symlink_rmt(
 424         xfs_inode_t     *ip,
 425         xfs_trans_t     **tpp)
 426 {
 427         xfs_buf_t       *bp;
 428         int             committed;
 429         int             done;
 430         int             error;
 431         xfs_fsblock_t   first_block;
 432         xfs_bmap_free_t free_list;
 433         int             i;
 434         xfs_mount_t     *mp;
 435         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 436         int             nmaps;
 437         xfs_trans_t     *ntp;
 438         int             size;
 439         xfs_trans_t     *tp;
 440
 441         tp = *tpp;
 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         /*
 454          * Lock the inode, fix the size, and join it to the transaction.
 455          * Hold it so in the normal path, we still have it locked for
 456          * the second transaction.  In the error paths we need it
 457          * held so the cancel won't rele it, see below.
 458          */
 459         size = (int)ip->i_d.di_size;
 460         ip->i_d.di_size = 0;
 461         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 462         /*
 463          * Find the block(s) so we can inval and unmap them.
 464          */
 465         done = 0;
 466         xfs_bmap_init(&free_list, &first_block);
 467         nmaps = ARRAY_SIZE(mval);
 468         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 469                                 mval, &nmaps, 0);
 470         if (error)
 471                 goto error0;
 472         /*
 473          * Invalidate the block(s). No validation is done.
 474          */
 475         for (i = 0; i < nmaps; i++) {
 476                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 477                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 478                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 479                 if (!bp) {
 480                         error = ENOMEM;
 481                         goto error1;
 482                 }
 483                 xfs_trans_binval(tp, bp);
 484         }
 485         /*
 486          * Unmap the dead block(s) to the free_list.
 487          */
 488         if ((error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 489                         &first_block, &free_list, &done)))
 490                 goto error1;
 491         ASSERT(done);
 492         /*
 493          * Commit the first transaction.  This logs the EFI and the inode.
 494          */
 495         if ((error = xfs_bmap_finish(&tp, &free_list, &committed)))
 496                 goto error1;
 497         /*
 498          * The transaction must have been committed, since there were
 499          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 500          * The new tp has the extent freeing and EFDs.
 501          */
 502         ASSERT(committed);
 503         /*
 504          * The first xact was committed, so add the inode to the new one.
 505          * Mark it dirty so it will be logged and moved forward in the log as
 506          * part of every commit.
 507          */
 508         xfs_trans_ijoin(tp, ip, 0);
 509         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 510         /*
 511          * Get a new, empty transaction to return to our caller.
 512          */
 513         ntp = xfs_trans_dup(tp);
 514         /*
 515          * Commit the transaction containing extent freeing and EFDs.
 516          * If we get an error on the commit here or on the reserve below,
 517          * we need to unlock the inode since the new transaction doesn't
 518          * have the inode attached.
 519          */
 520         error = xfs_trans_commit(tp, 0);
 521         tp = ntp;
 522         if (error) {
 523                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 524                 goto error0;
 525         }
 526         /*
 527          * transaction commit worked ok so we can drop the extra ticket
 528          * reference that we gained in xfs_trans_dup()
 529          */
 530         xfs_log_ticket_put(tp->t_ticket);
 531
 532         /*
 533          * Remove the memory for extent descriptions (just bookkeeping).
 534          */
 535         if (ip->i_df.if_bytes)
 536                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 537         ASSERT(ip->i_df.if_bytes == 0);
 538         /*
 539          * Put an itruncate log reservation in the new transaction
 540          * for our caller.
 541          */
 542         if ((error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0,
 543                         XFS_TRANS_PERM_LOG_RES, XFS_ITRUNCATE_LOG_COUNT))) {
 544                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 545                 goto error0;
 546         }
 547
 548         xfs_trans_ijoin(tp, ip, 0);
 549         *tpp = tp;
 550         return 0;
 551
 552  error1:
 553         xfs_bmap_cancel(&free_list);
 554  error0:
 555         return error;
 556 }
 557
 558 /*
 559  * xfs_inactive_symlink - free a symlink
 560  */
 561 int
 562 xfs_inactive_symlink(
 563         struct xfs_inode        *ip,
 564         struct xfs_trans        **tp)
 565 {
 566         struct xfs_mount        *mp = ip->i_mount;
 567         int                     pathlen;
 568
 569         trace_xfs_inactive_symlink(ip);
 570
 571         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 572
 573         if (XFS_FORCED_SHUTDOWN(mp))
 574                 return XFS_ERROR(EIO);
 575
 576         /*
 577          * Zero length symlinks _can_ exist.
 578          */
 579         pathlen = (int)ip->i_d.di_size;
 580         if (!pathlen)
 581                 return 0;
 582
 583         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 584                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 585                          __func__, (unsigned long long)ip->i_ino, pathlen);
 586                 ASSERT(0);
 587                 return XFS_ERROR(EFSCORRUPTED);
 588         }
 589
 590         if (ip->i_df.if_flags & XFS_IFINLINE) {
 591                 if (ip->i_df.if_bytes > 0)
 592                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 593                                           XFS_DATA_FORK);
 594                 ASSERT(ip->i_df.if_bytes == 0);
 595                 return 0;
 596         }
 597
 598         /* remove the remote symlink */
 599         return xfs_inactive_symlink_rmt(ip, tp);
 600 }