Pileus Git - ~andy/linux/blob - fs/isofs/rock.c

   1 /*
   2  *  linux/fs/isofs/rock.c
   3  *
   4  *  (C) 1992, 1993  Eric Youngdale
   5  *
   6  *  Rock Ridge Extensions to iso9660
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/smp_lock.h>
  12
  13 #include "isofs.h"
  14 #include "rock.h"
  15
  16 /*
  17  * These functions are designed to read the system areas of a directory record
  18  * and extract relevant information.  There are different functions provided
  19  * depending upon what information we need at the time.  One function fills
  20  * out an inode structure, a second one extracts a filename, a third one
  21  * returns a symbolic link name, and a fourth one returns the extent number
  22  * for the file.
  23  */
  24
  25 #define SIG(A,B) ((A) | ((B) << 8))     /* isonum_721() */
  26
  27 struct rock_state {
  28         void *buffer;
  29         unsigned char *chr;
  30         int len;
  31         int cont_size;
  32         int cont_extent;
  33         int cont_offset;
  34         struct inode *inode;
  35 };
  36
  37 /*
  38  * This is a way of ensuring that we have something in the system
  39  * use fields that is compatible with Rock Ridge.  Return zero on success.
  40  */
  41
  42 static int check_sp(struct rock_ridge *rr, struct inode *inode)
  43 {
  44         if (rr->u.SP.magic[0] != 0xbe)
  45                 return -1;
  46         if (rr->u.SP.magic[1] != 0xef)
  47                 return -1;
  48         ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
  49         return 0;
  50 }
  51
  52 static void setup_rock_ridge(struct iso_directory_record *de,
  53                         struct inode *inode, struct rock_state *rs)
  54 {
  55         rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
  56         if (rs->len & 1)
  57                 (rs->len)++;
  58         rs->chr = (unsigned char *)de + rs->len;
  59         rs->len = *((unsigned char *)de) - rs->len;
  60         if (rs->len < 0)
  61                 rs->len = 0;
  62
  63         if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
  64                 rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
  65                 rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
  66                 if (rs->len < 0)
  67                         rs->len = 0;
  68         }
  69 }
  70
  71 static void init_rock_state(struct rock_state *rs, struct inode *inode)
  72 {
  73         memset(rs, 0, sizeof(*rs));
  74         rs->inode = inode;
  75 }
  76
  77 /*
  78  * Returns 0 if the caller should continue scanning, 1 if the scan must end
  79  * and -ve on error.
  80  */
  81 static int rock_continue(struct rock_state *rs)
  82 {
  83         int ret = 1;
  84         int blocksize = 1 << rs->inode->i_blkbits;
  85         const int min_de_size = offsetof(struct rock_ridge, u);
  86
  87         kfree(rs->buffer);
  88         rs->buffer = NULL;
  89
  90         if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
  91             (unsigned)rs->cont_size > blocksize ||
  92             (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
  93                 printk(KERN_NOTICE "rock: corrupted directory entry. "
  94                         "extent=%d, offset=%d, size=%d\n",
  95                         rs->cont_extent, rs->cont_offset, rs->cont_size);
  96                 ret = -EIO;
  97                 goto out;
  98         }
  99
 100         if (rs->cont_extent) {
 101                 struct buffer_head *bh;
 102
 103                 rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
 104                 if (!rs->buffer) {
 105                         ret = -ENOMEM;
 106                         goto out;
 107                 }
 108                 ret = -EIO;
 109                 bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
 110                 if (bh) {
 111                         memcpy(rs->buffer, bh->b_data + rs->cont_offset,
 112                                         rs->cont_size);
 113                         put_bh(bh);
 114                         rs->chr = rs->buffer;
 115                         rs->len = rs->cont_size;
 116                         rs->cont_extent = 0;
 117                         rs->cont_size = 0;
 118                         rs->cont_offset = 0;
 119                         return 0;
 120                 }
 121                 printk("Unable to read rock-ridge attributes\n");
 122         }
 123 out:
 124         kfree(rs->buffer);
 125         rs->buffer = NULL;
 126         return ret;
 127 }
 128
 129 /*
 130  * return length of name field; 0: not found, -1: to be ignored
 131  */
 132 int get_rock_ridge_filename(struct iso_directory_record *de,
 133                             char *retname, struct inode *inode)
 134 {
 135         struct rock_state rs;
 136         struct rock_ridge *rr;
 137         int sig;
 138         int retnamlen = 0;
 139         int truncate = 0;
 140         int ret = 0;
 141
 142         if (!ISOFS_SB(inode->i_sb)->s_rock)
 143                 return 0;
 144         *retname = 0;
 145
 146         init_rock_state(&rs, inode);
 147         setup_rock_ridge(de, inode, &rs);
 148 repeat:
 149
 150         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 151                 rr = (struct rock_ridge *)rs.chr;
 152                 if (rr->len < 3)
 153                         goto out;       /* Something got screwed up here */
 154                 sig = isonum_721(rs.chr);
 155                 rs.chr += rr->len;
 156                 rs.len -= rr->len;
 157                 if (rs.len < 0)
 158                         goto out;       /* corrupted isofs */
 159
 160                 switch (sig) {
 161                 case SIG('R', 'R'):
 162                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
 163                                 goto out;
 164                         break;
 165                 case SIG('S', 'P'):
 166                         if (check_sp(rr, inode))
 167                                 goto out;
 168                         break;
 169                 case SIG('C', 'E'):
 170                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 171                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 172                         rs.cont_size = isonum_733(rr->u.CE.size);
 173                         break;
 174                 case SIG('N', 'M'):
 175                         if (truncate)
 176                                 break;
 177                         if (rr->len < 5)
 178                                 break;
 179                         /*
 180                          * If the flags are 2 or 4, this indicates '.' or '..'.
 181                          * We don't want to do anything with this, because it
 182                          * screws up the code that calls us.  We don't really
 183                          * care anyways, since we can just use the non-RR
 184                          * name.
 185                          */
 186                         if (rr->u.NM.flags & 6)
 187                                 break;
 188
 189                         if (rr->u.NM.flags & ~1) {
 190                                 printk("Unsupported NM flag settings (%d)\n",
 191                                         rr->u.NM.flags);
 192                                 break;
 193                         }
 194                         if ((strlen(retname) + rr->len - 5) >= 254) {
 195                                 truncate = 1;
 196                                 break;
 197                         }
 198                         strncat(retname, rr->u.NM.name, rr->len - 5);
 199                         retnamlen += rr->len - 5;
 200                         break;
 201                 case SIG('R', 'E'):
 202                         kfree(rs.buffer);
 203                         return -1;
 204                 default:
 205                         break;
 206                 }
 207         }
 208         ret = rock_continue(&rs);
 209         if (ret == 0)
 210                 goto repeat;
 211         if (ret == 1)
 212                 return retnamlen; /* If 0, this file did not have a NM field */
 213 out:
 214         kfree(rs.buffer);
 215         return ret;
 216 }
 217
 218 static int
 219 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 220                                 struct inode *inode, int regard_xa)
 221 {
 222         int symlink_len = 0;
 223         int cnt, sig;
 224         struct inode *reloc;
 225         struct rock_ridge *rr;
 226         int rootflag;
 227         struct rock_state rs;
 228         int ret = 0;
 229
 230         if (!ISOFS_SB(inode->i_sb)->s_rock)
 231                 return 0;
 232
 233         init_rock_state(&rs, inode);
 234         setup_rock_ridge(de, inode, &rs);
 235         if (regard_xa) {
 236                 rs.chr += 14;
 237                 rs.len -= 14;
 238                 if (rs.len < 0)
 239                         rs.len = 0;
 240         }
 241
 242 repeat:
 243         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 244                 rr = (struct rock_ridge *)rs.chr;
 245                 if (rr->len < 3)
 246                         goto out;       /* Something got screwed up here */
 247                 sig = isonum_721(rs.chr);
 248                 rs.chr += rr->len;
 249                 rs.len -= rr->len;
 250                 if (rs.len < 0)
 251                         goto out;       /* corrupted isofs */
 252
 253                 switch (sig) {
 254 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 255                 case SIG('R', 'R'):
 256                         if ((rr->u.RR.flags[0] &
 257                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 258                                 goto out;
 259                         break;
 260 #endif
 261                 case SIG('S', 'P'):
 262                         if (check_sp(rr, inode))
 263                                 goto out;
 264                         break;
 265                 case SIG('C', 'E'):
 266                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 267                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 268                         rs.cont_size = isonum_733(rr->u.CE.size);
 269                         break;
 270                 case SIG('E', 'R'):
 271                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 272                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 273                         {
 274                                 int p;
 275                                 for (p = 0; p < rr->u.ER.len_id; p++)
 276                                         printk("%c", rr->u.ER.data[p]);
 277                         }
 278                         printk("\n");
 279                         break;
 280                 case SIG('P', 'X'):
 281                         inode->i_mode = isonum_733(rr->u.PX.mode);
 282                         inode->i_nlink = isonum_733(rr->u.PX.n_links);
 283                         inode->i_uid = isonum_733(rr->u.PX.uid);
 284                         inode->i_gid = isonum_733(rr->u.PX.gid);
 285                         break;
 286                 case SIG('P', 'N'):
 287                         {
 288                                 int high, low;
 289                                 high = isonum_733(rr->u.PN.dev_high);
 290                                 low = isonum_733(rr->u.PN.dev_low);
 291                                 /*
 292                                  * The Rock Ridge standard specifies that if
 293                                  * sizeof(dev_t) <= 4, then the high field is
 294                                  * unused, and the device number is completely
 295                                  * stored in the low field.  Some writers may
 296                                  * ignore this subtlety,
 297                                  * and as a result we test to see if the entire
 298                                  * device number is
 299                                  * stored in the low field, and use that.
 300                                  */
 301                                 if ((low & ~0xff) && high == 0) {
 302                                         inode->i_rdev =
 303                                             MKDEV(low >> 8, low & 0xff);
 304                                 } else {
 305                                         inode->i_rdev =
 306                                             MKDEV(high, low);
 307                                 }
 308                         }
 309                         break;
 310                 case SIG('T', 'F'):
 311                         /*
 312                          * Some RRIP writers incorrectly place ctime in the
 313                          * TF_CREATE field. Try to handle this correctly for
 314                          * either case.
 315                          */
 316                         /* Rock ridge never appears on a High Sierra disk */
 317                         cnt = 0;
 318                         if (rr->u.TF.flags & TF_CREATE) {
 319                                 inode->i_ctime.tv_sec =
 320                                     iso_date(rr->u.TF.times[cnt++].time,
 321                                              0);
 322                                 inode->i_ctime.tv_nsec = 0;
 323                         }
 324                         if (rr->u.TF.flags & TF_MODIFY) {
 325                                 inode->i_mtime.tv_sec =
 326                                     iso_date(rr->u.TF.times[cnt++].time,
 327                                              0);
 328                                 inode->i_mtime.tv_nsec = 0;
 329                         }
 330                         if (rr->u.TF.flags & TF_ACCESS) {
 331                                 inode->i_atime.tv_sec =
 332                                     iso_date(rr->u.TF.times[cnt++].time,
 333                                              0);
 334                                 inode->i_atime.tv_nsec = 0;
 335                         }
 336                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 337                                 inode->i_ctime.tv_sec =
 338                                     iso_date(rr->u.TF.times[cnt++].time,
 339                                              0);
 340                                 inode->i_ctime.tv_nsec = 0;
 341                         }
 342                         break;
 343                 case SIG('S', 'L'):
 344                         {
 345                                 int slen;
 346                                 struct SL_component *slp;
 347                                 struct SL_component *oldslp;
 348                                 slen = rr->len - 5;
 349                                 slp = &rr->u.SL.link;
 350                                 inode->i_size = symlink_len;
 351                                 while (slen > 1) {
 352                                         rootflag = 0;
 353                                         switch (slp->flags & ~1) {
 354                                         case 0:
 355                                                 inode->i_size +=
 356                                                     slp->len;
 357                                                 break;
 358                                         case 2:
 359                                                 inode->i_size += 1;
 360                                                 break;
 361                                         case 4:
 362                                                 inode->i_size += 2;
 363                                                 break;
 364                                         case 8:
 365                                                 rootflag = 1;
 366                                                 inode->i_size += 1;
 367                                                 break;
 368                                         default:
 369                                                 printk("Symlink component flag "
 370                                                         "not implemented\n");
 371                                         }
 372                                         slen -= slp->len + 2;
 373                                         oldslp = slp;
 374                                         slp = (struct SL_component *)
 375                                                 (((char *)slp) + slp->len + 2);
 376
 377                                         if (slen < 2) {
 378                                                 if (((rr->u.SL.
 379                                                       flags & 1) != 0)
 380                                                     &&
 381                                                     ((oldslp->
 382                                                       flags & 1) == 0))
 383                                                         inode->i_size +=
 384                                                             1;
 385                                                 break;
 386                                         }
 387
 388                                         /*
 389                                          * If this component record isn't
 390                                          * continued, then append a '/'.
 391                                          */
 392                                         if (!rootflag
 393                                             && (oldslp->flags & 1) == 0)
 394                                                 inode->i_size += 1;
 395                                 }
 396                         }
 397                         symlink_len = inode->i_size;
 398                         break;
 399                 case SIG('R', 'E'):
 400                         printk(KERN_WARNING "Attempt to read inode for "
 401                                         "relocated directory\n");
 402                         goto out;
 403                 case SIG('C', 'L'):
 404                         ISOFS_I(inode)->i_first_extent =
 405                             isonum_733(rr->u.CL.location);
 406                         reloc =
 407                             isofs_iget(inode->i_sb,
 408                                        ISOFS_I(inode)->i_first_extent,
 409                                        0);
 410                         if (!reloc)
 411                                 goto out;
 412                         inode->i_mode = reloc->i_mode;
 413                         inode->i_nlink = reloc->i_nlink;
 414                         inode->i_uid = reloc->i_uid;
 415                         inode->i_gid = reloc->i_gid;
 416                         inode->i_rdev = reloc->i_rdev;
 417                         inode->i_size = reloc->i_size;
 418                         inode->i_blocks = reloc->i_blocks;
 419                         inode->i_atime = reloc->i_atime;
 420                         inode->i_ctime = reloc->i_ctime;
 421                         inode->i_mtime = reloc->i_mtime;
 422                         iput(reloc);
 423                         break;
 424 #ifdef CONFIG_ZISOFS
 425                 case SIG('Z', 'F'): {
 426                         int algo;
 427
 428                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 429                                 break;
 430                         algo = isonum_721(rr->u.ZF.algorithm);
 431                         if (algo == SIG('p', 'z')) {
 432                                 int block_shift =
 433                                         isonum_711(&rr->u.ZF.parms[1]);
 434                                 if (block_shift < PAGE_CACHE_SHIFT
 435                                                 || block_shift > 17) {
 436                                         printk(KERN_WARNING "isofs: "
 437                                                 "Can't handle ZF block "
 438                                                 "size of 2^%d\n",
 439                                                 block_shift);
 440                                 } else {
 441                                         /*
 442                                          * Note: we don't change
 443                                          * i_blocks here
 444                                          */
 445                                         ISOFS_I(inode)->i_file_format =
 446                                                 isofs_file_compressed;
 447                                         /*
 448                                          * Parameters to compression
 449                                          * algorithm (header size,
 450                                          * block size)
 451                                          */
 452                                         ISOFS_I(inode)->i_format_parm[0] =
 453                                                 isonum_711(&rr->u.ZF.parms[0]);
 454                                         ISOFS_I(inode)->i_format_parm[1] =
 455                                                 isonum_711(&rr->u.ZF.parms[1]);
 456                                         inode->i_size =
 457                                             isonum_733(rr->u.ZF.
 458                                                        real_size);
 459                                 }
 460                         } else {
 461                                 printk(KERN_WARNING
 462                                        "isofs: Unknown ZF compression "
 463                                                 "algorithm: %c%c\n",
 464                                        rr->u.ZF.algorithm[0],
 465                                        rr->u.ZF.algorithm[1]);
 466                         }
 467                         break;
 468                 }
 469 #endif
 470                 default:
 471                         break;
 472                 }
 473         }
 474         ret = rock_continue(&rs);
 475         if (ret == 0)
 476                 goto repeat;
 477         if (ret == 1)
 478                 ret = 0;
 479 out:
 480         kfree(rs.buffer);
 481         return ret;
 482 }
 483
 484 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 485 {
 486         int slen;
 487         int rootflag;
 488         struct SL_component *oldslp;
 489         struct SL_component *slp;
 490         slen = rr->len - 5;
 491         slp = &rr->u.SL.link;
 492         while (slen > 1) {
 493                 rootflag = 0;
 494                 switch (slp->flags & ~1) {
 495                 case 0:
 496                         if (slp->len > plimit - rpnt)
 497                                 return NULL;
 498                         memcpy(rpnt, slp->text, slp->len);
 499                         rpnt += slp->len;
 500                         break;
 501                 case 2:
 502                         if (rpnt >= plimit)
 503                                 return NULL;
 504                         *rpnt++ = '.';
 505                         break;
 506                 case 4:
 507                         if (2 > plimit - rpnt)
 508                                 return NULL;
 509                         *rpnt++ = '.';
 510                         *rpnt++ = '.';
 511                         break;
 512                 case 8:
 513                         if (rpnt >= plimit)
 514                                 return NULL;
 515                         rootflag = 1;
 516                         *rpnt++ = '/';
 517                         break;
 518                 default:
 519                         printk("Symlink component flag not implemented (%d)\n",
 520                                slp->flags);
 521                 }
 522                 slen -= slp->len + 2;
 523                 oldslp = slp;
 524                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 525
 526                 if (slen < 2) {
 527                         /*
 528                          * If there is another SL record, and this component
 529                          * record isn't continued, then add a slash.
 530                          */
 531                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 532                             !(oldslp->flags & 1)) {
 533                                 if (rpnt >= plimit)
 534                                         return NULL;
 535                                 *rpnt++ = '/';
 536                         }
 537                         break;
 538                 }
 539
 540                 /*
 541                  * If this component record isn't continued, then append a '/'.
 542                  */
 543                 if (!rootflag && !(oldslp->flags & 1)) {
 544                         if (rpnt >= plimit)
 545                                 return NULL;
 546                         *rpnt++ = '/';
 547                 }
 548         }
 549         return rpnt;
 550 }
 551
 552 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
 553 {
 554         int result = parse_rock_ridge_inode_internal(de, inode, 0);
 555
 556         /*
 557          * if rockridge flag was reset and we didn't look for attributes
 558          * behind eventual XA attributes, have a look there
 559          */
 560         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 561             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 562                 result = parse_rock_ridge_inode_internal(de, inode, 14);
 563         }
 564         return result;
 565 }
 566
 567 /*
 568  * readpage() for symlinks: reads symlink contents into the page and either
 569  * makes it uptodate and returns 0 or returns error (-EIO)
 570  */
 571 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 572 {
 573         struct inode *inode = page->mapping->host;
 574         struct iso_inode_info *ei = ISOFS_I(inode);
 575         char *link = kmap(page);
 576         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 577         struct buffer_head *bh;
 578         char *rpnt = link;
 579         unsigned char *pnt;
 580         struct iso_directory_record *raw_de;
 581         unsigned long block, offset;
 582         int sig;
 583         struct rock_ridge *rr;
 584         struct rock_state rs;
 585         int ret;
 586
 587         if (!ISOFS_SB(inode->i_sb)->s_rock)
 588                 goto error;
 589
 590         init_rock_state(&rs, inode);
 591         block = ei->i_iget5_block;
 592         lock_kernel();
 593         bh = sb_bread(inode->i_sb, block);
 594         if (!bh)
 595                 goto out_noread;
 596
 597         offset = ei->i_iget5_offset;
 598         pnt = (unsigned char *)bh->b_data + offset;
 599
 600         raw_de = (struct iso_directory_record *)pnt;
 601
 602         /*
 603          * If we go past the end of the buffer, there is some sort of error.
 604          */
 605         if (offset + *pnt > bufsize)
 606                 goto out_bad_span;
 607
 608         /*
 609          * Now test for possible Rock Ridge extensions which will override
 610          * some of these numbers in the inode structure.
 611          */
 612
 613         setup_rock_ridge(raw_de, inode, &rs);
 614
 615 repeat:
 616         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 617                 rr = (struct rock_ridge *)rs.chr;
 618                 if (rr->len < 3)
 619                         goto out;       /* Something got screwed up here */
 620                 sig = isonum_721(rs.chr);
 621                 rs.chr += rr->len;
 622                 rs.len -= rr->len;
 623                 if (rs.len < 0)
 624                         goto out;       /* corrupted isofs */
 625
 626                 switch (sig) {
 627                 case SIG('R', 'R'):
 628                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 629                                 goto out;
 630                         break;
 631                 case SIG('S', 'P'):
 632                         if (check_sp(rr, inode))
 633                                 goto out;
 634                         break;
 635                 case SIG('S', 'L'):
 636                         rpnt = get_symlink_chunk(rpnt, rr,
 637                                                  link + (PAGE_SIZE - 1));
 638                         if (rpnt == NULL)
 639                                 goto out;
 640                         break;
 641                 case SIG('C', 'E'):
 642                         /* This tells is if there is a continuation record */
 643                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 644                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 645                         rs.cont_size = isonum_733(rr->u.CE.size);
 646                 default:
 647                         break;
 648                 }
 649         }
 650         ret = rock_continue(&rs);
 651         if (ret == 0)
 652                 goto repeat;
 653         if (ret < 0)
 654                 goto fail;
 655
 656         if (rpnt == link)
 657                 goto fail;
 658         brelse(bh);
 659         *rpnt = '\0';
 660         unlock_kernel();
 661         SetPageUptodate(page);
 662         kunmap(page);
 663         unlock_page(page);
 664         return 0;
 665
 666         /* error exit from macro */
 667 out:
 668         kfree(rs.buffer);
 669         goto fail;
 670 out_noread:
 671         printk("unable to read i-node block");
 672         goto fail;
 673 out_bad_span:
 674         printk("symlink spans iso9660 blocks\n");
 675 fail:
 676         brelse(bh);
 677         unlock_kernel();
 678 error:
 679         SetPageError(page);
 680         kunmap(page);
 681         unlock_page(page);
 682         return -EIO;
 683 }
 684
 685 struct address_space_operations isofs_symlink_aops = {
 686         .readpage = rock_ridge_symlink_readpage
 687 };