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_dir2.h"
  30 #include "xfs_inode.h"
  31 #include "xfs_ialloc.h"
  32 #include "xfs_alloc.h"
  33 #include "xfs_bmap.h"
  34 #include "xfs_bmap_btree.h"
  35 #include "xfs_bmap_util.h"
  36 #include "xfs_error.h"
  37 #include "xfs_quota.h"
  38 #include "xfs_trans_space.h"
  39 #include "xfs_trace.h"
  40 #include "xfs_symlink.h"
  41 #include "xfs_trans.h"
  42 #include "xfs_log.h"
  43
  44 /* ----- Kernel only functions below ----- */
  45 STATIC int
  46 xfs_readlink_bmap(
  47         struct xfs_inode        *ip,
  48         char                    *link)
  49 {
  50         struct xfs_mount        *mp = ip->i_mount;
  51         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
  52         struct xfs_buf          *bp;
  53         xfs_daddr_t             d;
  54         char                    *cur_chunk;
  55         int                     pathlen = ip->i_d.di_size;
  56         int                     nmaps = XFS_SYMLINK_MAPS;
  57         int                     byte_cnt;
  58         int                     n;
  59         int                     error = 0;
  60         int                     fsblocks = 0;
  61         int                     offset;
  62
  63         fsblocks = xfs_symlink_blocks(mp, pathlen);
  64         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
  65         if (error)
  66                 goto out;
  67
  68         offset = 0;
  69         for (n = 0; n < nmaps; n++) {
  70                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
  71                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
  72
  73                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
  74                                   &xfs_symlink_buf_ops);
  75                 if (!bp)
  76                         return -ENOMEM;
  77                 error = bp->b_error;
  78                 if (error) {
  79                         xfs_buf_ioerror_alert(bp, __func__);
  80                         xfs_buf_relse(bp);
  81
  82                         /* bad CRC means corrupted metadata */
  83                         if (error == -EFSBADCRC)
  84                                 error = -EFSCORRUPTED;
  85                         goto out;
  86                 }
  87                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
  88                 if (pathlen < byte_cnt)
  89                         byte_cnt = pathlen;
  90
  91                 cur_chunk = bp->b_addr;
  92                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
  93                         if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
  94                                                         byte_cnt, bp)) {
  95                                 error = -EFSCORRUPTED;
  96                                 xfs_alert(mp,
  97 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
  98                                         offset, byte_cnt, ip->i_ino);
  99                                 xfs_buf_relse(bp);
 100                                 goto out;
 101
 102                         }
 103
 104                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 105                 }
 106
 107                 memcpy(link + offset, cur_chunk, byte_cnt);
 108
 109                 pathlen -= byte_cnt;
 110                 offset += byte_cnt;
 111
 112                 xfs_buf_relse(bp);
 113         }
 114         ASSERT(pathlen == 0);
 115
 116         link[ip->i_d.di_size] = '\0';
 117         error = 0;
 118
 119  out:
 120         return error;
 121 }
 122
 123 int
 124 xfs_readlink(
 125         struct xfs_inode *ip,
 126         char            *link)
 127 {
 128         struct xfs_mount *mp = ip->i_mount;
 129         xfs_fsize_t     pathlen;
 130         int             error = 0;
 131
 132         trace_xfs_readlink(ip);
 133
 134         if (XFS_FORCED_SHUTDOWN(mp))
 135                 return -EIO;
 136
 137         xfs_ilock(ip, XFS_ILOCK_SHARED);
 138
 139         pathlen = ip->i_d.di_size;
 140         if (!pathlen)
 141                 goto out;
 142
 143         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 144                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 145                          __func__, (unsigned long long) ip->i_ino,
 146                          (long long) pathlen);
 147                 ASSERT(0);
 148                 error = -EFSCORRUPTED;
 149                 goto out;
 150         }
 151
 152
 153         if (ip->i_df.if_flags & XFS_IFINLINE) {
 154                 memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 155                 link[pathlen] = '\0';
 156         } else {
 157                 error = xfs_readlink_bmap(ip, link);
 158         }
 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_bmap_free    free_list;
 179         xfs_fsblock_t           first_block;
 180         bool                    unlock_dp_on_error = false;
 181         int                     committed;
 182         xfs_fileoff_t           first_fsb;
 183         xfs_filblks_t           fs_blocks;
 184         int                     nmaps;
 185         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 186         xfs_daddr_t             d;
 187         const char              *cur_chunk;
 188         int                     byte_cnt;
 189         int                     n;
 190         xfs_buf_t               *bp;
 191         prid_t                  prid;
 192         struct xfs_dquot        *udqp = NULL;
 193         struct xfs_dquot        *gdqp = NULL;
 194         struct xfs_dquot        *pdqp = NULL;
 195         uint                    resblks;
 196
 197         *ipp = NULL;
 198
 199         trace_xfs_symlink(dp, link_name);
 200
 201         if (XFS_FORCED_SHUTDOWN(mp))
 202                 return -EIO;
 203
 204         /*
 205          * Check component lengths of the target path name.
 206          */
 207         pathlen = strlen(target_path);
 208         if (pathlen >= MAXPATHLEN)      /* total string too long */
 209                 return -ENAMETOOLONG;
 210
 211         udqp = gdqp = NULL;
 212         prid = xfs_get_initial_prid(dp);
 213
 214         /*
 215          * Make sure that we have allocated dquot(s) on disk.
 216          */
 217         error = xfs_qm_vop_dqalloc(dp,
 218                         xfs_kuid_to_uid(current_fsuid()),
 219                         xfs_kgid_to_gid(current_fsgid()), prid,
 220                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 221                         &udqp, &gdqp, &pdqp);
 222         if (error)
 223                 return error;
 224
 225         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 226         /*
 227          * The symlink will fit into the inode data fork?
 228          * There can't be any attributes so we get the whole variable part.
 229          */
 230         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 231                 fs_blocks = 0;
 232         else
 233                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 234         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 235         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
 236         if (error == -ENOSPC && fs_blocks == 0) {
 237                 resblks = 0;
 238                 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
 239         }
 240         if (error)
 241                 goto out_trans_cancel;
 242
 243         xfs_ilock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL |
 244                       XFS_IOLOCK_PARENT | 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 = -EPERM;
 252                 goto out_trans_cancel;
 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 out_trans_cancel;
 262
 263         /*
 264          * Check for ability to enter directory entry, if no space reserved.
 265          */
 266         if (!resblks) {
 267                 error = xfs_dir_canenter(tp, dp, link_name);
 268                 if (error)
 269                         goto out_trans_cancel;
 270         }
 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                 goto out_trans_cancel;
 284
 285         /*
 286          * Now we join the directory inode to the transaction.  We do not do it
 287          * earlier because xfs_dir_ialloc might commit the previous transaction
 288          * (and release all the locks).  An error from here on will result in
 289          * the transaction cancel unlocking dp so don't do it explicitly in the
 290          * error path.
 291          */
 292         xfs_trans_ijoin(tp, dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 293         unlock_dp_on_error = false;
 294
 295         /*
 296          * Also attach the dquot(s) to it, if applicable.
 297          */
 298         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 299
 300         if (resblks)
 301                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 302         /*
 303          * If the symlink will fit into the inode, write it inline.
 304          */
 305         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 306                 xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 307                 memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 308                 ip->i_d.di_size = pathlen;
 309
 310                 /*
 311                  * The inode was initially created in extent format.
 312                  */
 313                 ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 314                 ip->i_df.if_flags |= XFS_IFINLINE;
 315
 316                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 317                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 318
 319         } else {
 320                 int     offset;
 321
 322                 first_fsb = 0;
 323                 nmaps = XFS_SYMLINK_MAPS;
 324
 325                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 326                                   XFS_BMAPI_METADATA, &first_block, resblks,
 327                                   mval, &nmaps, &free_list);
 328                 if (error)
 329                         goto out_bmap_cancel;
 330
 331                 if (resblks)
 332                         resblks -= fs_blocks;
 333                 ip->i_d.di_size = pathlen;
 334                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 335
 336                 cur_chunk = target_path;
 337                 offset = 0;
 338                 for (n = 0; n < nmaps; n++) {
 339                         char    *buf;
 340
 341                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 342                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 343                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 344                                                BTOBB(byte_cnt), 0);
 345                         if (!bp) {
 346                                 error = -ENOMEM;
 347                                 goto out_bmap_cancel;
 348                         }
 349                         bp->b_ops = &xfs_symlink_buf_ops;
 350
 351                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 352                         byte_cnt = min(byte_cnt, pathlen);
 353
 354                         buf = bp->b_addr;
 355                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 356                                                    byte_cnt, bp);
 357
 358                         memcpy(buf, cur_chunk, byte_cnt);
 359
 360                         cur_chunk += byte_cnt;
 361                         pathlen -= byte_cnt;
 362                         offset += byte_cnt;
 363
 364                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 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 out_bmap_cancel;
 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 out_bmap_cancel;
 393
 394         error = xfs_trans_commit(tp);
 395         if (error)
 396                 goto out_release_inode;
 397
 398         xfs_qm_dqrele(udqp);
 399         xfs_qm_dqrele(gdqp);
 400         xfs_qm_dqrele(pdqp);
 401
 402         *ipp = ip;
 403         return 0;
 404
 405 out_bmap_cancel:
 406         xfs_bmap_cancel(&free_list);
 407 out_trans_cancel:
 408         xfs_trans_cancel(tp);
 409 out_release_inode:
 410         /*
 411          * Wait until after the current transaction is aborted to finish the
 412          * setup of the inode and release the inode.  This prevents recursive
 413          * transactions and deadlocks from xfs_inactive.
 414          */
 415         if (ip) {
 416                 xfs_finish_inode_setup(ip);
 417                 IRELE(ip);
 418         }
 419
 420         xfs_qm_dqrele(udqp);
 421         xfs_qm_dqrele(gdqp);
 422         xfs_qm_dqrele(pdqp);
 423
 424         if (unlock_dp_on_error)
 425                 xfs_iunlock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 426         return error;
 427 }
 428
 429 /*
 430  * Free a symlink that has blocks associated with it.
 431  */
 432 STATIC int
 433 xfs_inactive_symlink_rmt(
 434         struct xfs_inode *ip)
 435 {
 436         xfs_buf_t       *bp;
 437         int             committed;
 438         int             done;
 439         int             error;
 440         xfs_fsblock_t   first_block;
 441         xfs_bmap_free_t free_list;
 442         int             i;
 443         xfs_mount_t     *mp;
 444         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 445         int             nmaps;
 446         int             size;
 447         xfs_trans_t     *tp;
 448
 449         mp = ip->i_mount;
 450         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 451         /*
 452          * We're freeing a symlink that has some
 453          * blocks allocated to it.  Free the
 454          * blocks here.  We know that we've got
 455          * either 1 or 2 extents and that we can
 456          * free them all in one bunmapi call.
 457          */
 458         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 459
 460         tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
 461         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 462         if (error) {
 463                 xfs_trans_cancel(tp);
 464                 return error;
 465         }
 466
 467         xfs_ilock(ip, XFS_ILOCK_EXCL);
 468         xfs_trans_ijoin(tp, ip, 0);
 469
 470         /*
 471          * Lock the inode, fix the size, and join it to the transaction.
 472          * Hold it so in the normal path, we still have it locked for
 473          * the second transaction.  In the error paths we need it
 474          * held so the cancel won't rele it, see below.
 475          */
 476         size = (int)ip->i_d.di_size;
 477         ip->i_d.di_size = 0;
 478         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 479         /*
 480          * Find the block(s) so we can inval and unmap them.
 481          */
 482         done = 0;
 483         xfs_bmap_init(&free_list, &first_block);
 484         nmaps = ARRAY_SIZE(mval);
 485         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 486                                 mval, &nmaps, 0);
 487         if (error)
 488                 goto error_trans_cancel;
 489         /*
 490          * Invalidate the block(s). No validation is done.
 491          */
 492         for (i = 0; i < nmaps; i++) {
 493                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 494                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 495                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 496                 if (!bp) {
 497                         error = -ENOMEM;
 498                         goto error_bmap_cancel;
 499                 }
 500                 xfs_trans_binval(tp, bp);
 501         }
 502         /*
 503          * Unmap the dead block(s) to the free_list.
 504          */
 505         error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps,
 506                             &first_block, &free_list, &done);
 507         if (error)
 508                 goto error_bmap_cancel;
 509         ASSERT(done);
 510         /*
 511          * Commit the first transaction.  This logs the EFI and the inode.
 512          */
 513         error = xfs_bmap_finish(&tp, &free_list, &committed);
 514         if (error)
 515                 goto error_bmap_cancel;
 516         /*
 517          * The transaction must have been committed, since there were
 518          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 519          * The new tp has the extent freeing and EFDs.
 520          */
 521         ASSERT(committed);
 522         /*
 523          * The first xact was committed, so add the inode to the new one.
 524          * Mark it dirty so it will be logged and moved forward in the log as
 525          * part of every commit.
 526          */
 527         xfs_trans_ijoin(tp, ip, 0);
 528         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 529         /*
 530          * Commit the transaction containing extent freeing and EFDs.
 531          */
 532         error = xfs_trans_commit(tp);
 533         if (error) {
 534                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 535                 goto error_unlock;
 536         }
 537
 538         /*
 539          * Remove the memory for extent descriptions (just bookkeeping).
 540          */
 541         if (ip->i_df.if_bytes)
 542                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 543         ASSERT(ip->i_df.if_bytes == 0);
 544
 545         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 546         return 0;
 547
 548 error_bmap_cancel:
 549         xfs_bmap_cancel(&free_list);
 550 error_trans_cancel:
 551         xfs_trans_cancel(tp);
 552 error_unlock:
 553         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 554         return error;
 555 }
 556
 557 /*
 558  * xfs_inactive_symlink - free a symlink
 559  */
 560 int
 561 xfs_inactive_symlink(
 562         struct xfs_inode        *ip)
 563 {
 564         struct xfs_mount        *mp = ip->i_mount;
 565         int                     pathlen;
 566
 567         trace_xfs_inactive_symlink(ip);
 568
 569         if (XFS_FORCED_SHUTDOWN(mp))
 570                 return -EIO;
 571
 572         xfs_ilock(ip, XFS_ILOCK_EXCL);
 573
 574         /*
 575          * Zero length symlinks _can_ exist.
 576          */
 577         pathlen = (int)ip->i_d.di_size;
 578         if (!pathlen) {
 579                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 580                 return 0;
 581         }
 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                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 587                 ASSERT(0);
 588                 return -EFSCORRUPTED;
 589         }
 590
 591         if (ip->i_df.if_flags & XFS_IFINLINE) {
 592                 if (ip->i_df.if_bytes > 0)
 593                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 594                                           XFS_DATA_FORK);
 595                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 596                 ASSERT(ip->i_df.if_bytes == 0);
 597                 return 0;
 598         }
 599
 600         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 601
 602         /* remove the remote symlink */
 603         return xfs_inactive_symlink_rmt(ip);
 604 }