kernel/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, bp->b_addr, 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         uint                    cancel_flags;
 182         int                     committed;
 183         xfs_fileoff_t           first_fsb;
 184         xfs_filblks_t           fs_blocks;
 185         int                     nmaps;
 186         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 187         xfs_daddr_t             d;
 188         const char              *cur_chunk;
 189         int                     byte_cnt;
 190         int                     n;
 191         xfs_buf_t               *bp;
 192         prid_t                  prid;
 193         struct xfs_dquot        *udqp = NULL;
 194         struct xfs_dquot        *gdqp = NULL;
 195         struct xfs_dquot        *pdqp = NULL;
 196         uint                    resblks;
 197
 198         *ipp = NULL;
 199
 200         trace_xfs_symlink(dp, link_name);
 201
 202         if (XFS_FORCED_SHUTDOWN(mp))
 203                 return -EIO;
 204
 205         /*
 206          * Check component lengths of the target path name.
 207          */
 208         pathlen = strlen(target_path);
 209         if (pathlen >= MAXPATHLEN)      /* total string too long */
 210                 return -ENAMETOOLONG;
 211
 212         udqp = gdqp = NULL;
 213         prid = xfs_get_initial_prid(dp);
 214
 215         /*
 216          * Make sure that we have allocated dquot(s) on disk.
 217          */
 218         error = xfs_qm_vop_dqalloc(dp,
 219                         xfs_kuid_to_uid(current_fsuid()),
 220                         xfs_kgid_to_gid(current_fsgid()), prid,
 221                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 222                         &udqp, &gdqp, &pdqp);
 223         if (error)
 224                 return error;
 225
 226         tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 227         cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 228         /*
 229          * The symlink will fit into the inode data fork?
 230          * There can't be any attributes so we get the whole variable part.
 231          */
 232         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 233                 fs_blocks = 0;
 234         else
 235                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 236         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 237         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
 238         if (error == -ENOSPC && fs_blocks == 0) {
 239                 resblks = 0;
 240                 error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
 241         }
 242         if (error) {
 243                 cancel_flags = 0;
 244                 goto out_trans_cancel;
 245         }
 246
 247         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 248         unlock_dp_on_error = true;
 249
 250         /*
 251          * Check whether the directory allows new symlinks or not.
 252          */
 253         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 254                 error = -EPERM;
 255                 goto out_trans_cancel;
 256         }
 257
 258         /*
 259          * Reserve disk quota : blocks and inode.
 260          */
 261         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 262                                                 pdqp, resblks, 1, 0);
 263         if (error)
 264                 goto out_trans_cancel;
 265
 266         /*
 267          * Check for ability to enter directory entry, if no space reserved.
 268          */
 269         if (!resblks) {
 270                 error = xfs_dir_canenter(tp, dp, link_name);
 271                 if (error)
 272                         goto out_trans_cancel;
 273         }
 274         /*
 275          * Initialize the bmap freelist prior to calling either
 276          * bmapi or the directory create code.
 277          */
 278         xfs_bmap_init(&free_list, &first_block);
 279
 280         /*
 281          * Allocate an inode for the symlink.
 282          */
 283         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 284                                prid, resblks > 0, &ip, NULL);
 285         if (error)
 286                 goto out_trans_cancel;
 287
 288         /*
 289          * Now we join the directory inode to the transaction.  We do not do it
 290          * earlier because xfs_dir_ialloc might commit the previous transaction
 291          * (and release all the locks).  An error from here on will result in
 292          * the 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 out_bmap_cancel;
 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 out_bmap_cancel;
 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 out_bmap_cancel;
 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 out_bmap_cancel;
 396
 397         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 398         if (error)
 399                 goto out_release_inode;
 400
 401         xfs_qm_dqrele(udqp);
 402         xfs_qm_dqrele(gdqp);
 403         xfs_qm_dqrele(pdqp);
 404
 405         *ipp = ip;
 406         return 0;
 407
 408 out_bmap_cancel:
 409         xfs_bmap_cancel(&free_list);
 410         cancel_flags |= XFS_TRANS_ABORT;
 411 out_trans_cancel:
 412         xfs_trans_cancel(tp, cancel_flags);
 413 out_release_inode:
 414         /*
 415          * Wait until after the current transaction is aborted to finish the
 416          * setup of the inode and release the inode.  This prevents recursive
 417          * transactions and deadlocks from xfs_inactive.
 418          */
 419         if (ip) {
 420                 xfs_finish_inode_setup(ip);
 421                 IRELE(ip);
 422         }
 423
 424         xfs_qm_dqrele(udqp);
 425         xfs_qm_dqrele(gdqp);
 426         xfs_qm_dqrele(pdqp);
 427
 428         if (unlock_dp_on_error)
 429                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 430         return error;
 431 }
 432
 433 /*
 434  * Free a symlink that has blocks associated with it.
 435  */
 436 STATIC int
 437 xfs_inactive_symlink_rmt(
 438         struct xfs_inode *ip)
 439 {
 440         xfs_buf_t       *bp;
 441         int             committed;
 442         int             done;
 443         int             error;
 444         xfs_fsblock_t   first_block;
 445         xfs_bmap_free_t free_list;
 446         int             i;
 447         xfs_mount_t     *mp;
 448         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 449         int             nmaps;
 450         int             size;
 451         xfs_trans_t     *tp;
 452
 453         mp = ip->i_mount;
 454         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 455         /*
 456          * We're freeing a symlink that has some
 457          * blocks allocated to it.  Free the
 458          * blocks here.  We know that we've got
 459          * either 1 or 2 extents and that we can
 460          * free them all in one bunmapi call.
 461          */
 462         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 463
 464         tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
 465         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 466         if (error) {
 467                 xfs_trans_cancel(tp, 0);
 468                 return error;
 469         }
 470
 471         xfs_ilock(ip, XFS_ILOCK_EXCL);
 472         xfs_trans_ijoin(tp, ip, 0);
 473
 474         /*
 475          * Lock the inode, fix the size, and join it to the transaction.
 476          * Hold it so in the normal path, we still have it locked for
 477          * the second transaction.  In the error paths we need it
 478          * held so the cancel won't rele it, see below.
 479          */
 480         size = (int)ip->i_d.di_size;
 481         ip->i_d.di_size = 0;
 482         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 483         /*
 484          * Find the block(s) so we can inval and unmap them.
 485          */
 486         done = 0;
 487         xfs_bmap_init(&free_list, &first_block);
 488         nmaps = ARRAY_SIZE(mval);
 489         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 490                                 mval, &nmaps, 0);
 491         if (error)
 492                 goto error_trans_cancel;
 493         /*
 494          * Invalidate the block(s). No validation is done.
 495          */
 496         for (i = 0; i < nmaps; i++) {
 497                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 498                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 499                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 500                 if (!bp) {
 501                         error = -ENOMEM;
 502                         goto error_bmap_cancel;
 503                 }
 504                 xfs_trans_binval(tp, bp);
 505         }
 506         /*
 507          * Unmap the dead block(s) to the free_list.
 508          */
 509         error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 510                             &first_block, &free_list, &done);
 511         if (error)
 512                 goto error_bmap_cancel;
 513         ASSERT(done);
 514         /*
 515          * Commit the first transaction.  This logs the EFI and the inode.
 516          */
 517         error = xfs_bmap_finish(&tp, &free_list, &committed);
 518         if (error)
 519                 goto error_bmap_cancel;
 520         /*
 521          * The transaction must have been committed, since there were
 522          * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 523          * The new tp has the extent freeing and EFDs.
 524          */
 525         ASSERT(committed);
 526         /*
 527          * The first xact was committed, so add the inode to the new one.
 528          * Mark it dirty so it will be logged and moved forward in the log as
 529          * part of every commit.
 530          */
 531         xfs_trans_ijoin(tp, ip, 0);
 532         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 533         /*
 534          * Commit the transaction containing extent freeing and EFDs.
 535          */
 536         error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 537         if (error) {
 538                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 539                 goto error_unlock;
 540         }
 541
 542         /*
 543          * Remove the memory for extent descriptions (just bookkeeping).
 544          */
 545         if (ip->i_df.if_bytes)
 546                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 547         ASSERT(ip->i_df.if_bytes == 0);
 548
 549         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 550         return 0;
 551
 552 error_bmap_cancel:
 553         xfs_bmap_cancel(&free_list);
 554 error_trans_cancel:
 555         xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
 556 error_unlock:
 557         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 558         return error;
 559 }
 560
 561 /*
 562  * xfs_inactive_symlink - free a symlink
 563  */
 564 int
 565 xfs_inactive_symlink(
 566         struct xfs_inode        *ip)
 567 {
 568         struct xfs_mount        *mp = ip->i_mount;
 569         int                     pathlen;
 570
 571         trace_xfs_inactive_symlink(ip);
 572
 573         if (XFS_FORCED_SHUTDOWN(mp))
 574                 return -EIO;
 575
 576         xfs_ilock(ip, XFS_ILOCK_EXCL);
 577
 578         /*
 579          * Zero length symlinks _can_ exist.
 580          */
 581         pathlen = (int)ip->i_d.di_size;
 582         if (!pathlen) {
 583                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 584                 return 0;
 585         }
 586
 587         if (pathlen < 0 || pathlen > MAXPATHLEN) {
 588                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 589                          __func__, (unsigned long long)ip->i_ino, pathlen);
 590                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 591                 ASSERT(0);
 592                 return -EFSCORRUPTED;
 593         }
 594
 595         if (ip->i_df.if_flags & XFS_IFINLINE) {
 596                 if (ip->i_df.if_bytes > 0)
 597                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 598                                           XFS_DATA_FORK);
 599                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 600                 ASSERT(ip->i_df.if_bytes == 0);
 601                 return 0;
 602         }
 603
 604         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 605
 606         /* remove the remote symlink */
 607         return xfs_inactive_symlink_rmt(ip);
 608 }