1 /* $OpenBSD: setup.c,v 1.18 2011/03/12 17:50:47 deraadt Exp $ */ 2 /* $NetBSD: setup.c,v 1.1 1997/06/11 11:22:01 bouyer Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Manuel Bouyer. 6 * Copyright (c) 1980, 1986, 1993 7 * The Regents of the University of California. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #define DKTYPENAMES 35 #include <sys/param.h> 36 #include <sys/time.h> 37 #include <ufs/ext2fs/ext2fs_dinode.h> 38 #include <ufs/ext2fs/ext2fs.h> 39 #include <sys/stat.h> 40 #include <sys/ioctl.h> 41 #include <sys/dkio.h> 42 #include <sys/disklabel.h> 43 #include <sys/file.h> 44 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <ctype.h> 51 52 #include "fsck.h" 53 #include "extern.h" 54 #include "fsutil.h" 55 56 #define POWEROF2(num) (((num) & ((num) - 1)) == 0) 57 58 void badsb(int, char *); 59 int calcsb(char *, int, struct m_ext2fs *); 60 static struct disklabel *getdisklabel(char *, int); 61 static int readsb(int); 62 63 int 64 setup(char *dev) 65 { 66 long cg, asked, i; 67 long bmapsize; 68 struct disklabel *lp; 69 off_t sizepb; 70 struct stat statb; 71 struct m_ext2fs proto; 72 int doskipclean; 73 u_int64_t maxfilesize; 74 75 havesb = 0; 76 fswritefd = -1; 77 doskipclean = skipclean; 78 if (stat(dev, &statb) < 0) { 79 printf("Can't stat %s: %s\n", dev, strerror(errno)); 80 return (0); 81 } 82 if (!S_ISCHR(statb.st_mode)) { 83 pfatal("%s is not a character device", dev); 84 if (reply("CONTINUE") == 0) 85 return (0); 86 } 87 if ((fsreadfd = open(dev, O_RDONLY)) < 0) { 88 printf("Can't open %s: %s\n", dev, strerror(errno)); 89 return (0); 90 } 91 if (preen == 0) 92 printf("** %s", dev); 93 if (nflag || (fswritefd = open(dev, O_WRONLY)) < 0) { 94 fswritefd = -1; 95 if (preen) 96 pfatal("NO WRITE ACCESS"); 97 printf(" (NO WRITE)"); 98 } 99 if (preen == 0) 100 printf("\n"); 101 fsmodified = 0; 102 lfdir = 0; 103 initbarea(&sblk); 104 initbarea(&asblk); 105 sblk.b_un.b_buf = malloc(SBSIZE); 106 asblk.b_un.b_buf = malloc(SBSIZE); 107 if (sblk.b_un.b_buf == NULL || asblk.b_un.b_buf == NULL) 108 errexit("cannot allocate space for superblock\n"); 109 if ((lp = getdisklabel((char *)NULL, fsreadfd)) != NULL) 110 dev_bsize = secsize = lp->d_secsize; 111 else 112 dev_bsize = secsize = DEV_BSIZE; 113 /* 114 * Read in the superblock, looking for alternates if necessary 115 */ 116 if (readsb(1) == 0) { 117 if (bflag || preen || calcsb(dev, fsreadfd, &proto) == 0) 118 return(0); 119 if (reply("LOOK FOR ALTERNATE SUPERBLOCKS") == 0) 120 return (0); 121 for (cg = 1; cg < proto.e2fs_ncg; cg++) { 122 bflag = fsbtodb(&proto, 123 cg * proto.e2fs.e2fs_bpg + proto.e2fs.e2fs_first_dblock); 124 if (readsb(0) != 0) 125 break; 126 } 127 if (cg >= proto.e2fs_ncg) { 128 printf("%s %s\n%s %s\n%s %s\n", 129 "SEARCH FOR ALTERNATE SUPER-BLOCK", 130 "FAILED. YOU MUST USE THE", 131 "-b OPTION TO FSCK_FFS TO SPECIFY THE", 132 "LOCATION OF AN ALTERNATE", 133 "SUPER-BLOCK TO SUPPLY NEEDED", 134 "INFORMATION; SEE fsck_ext2fs(8)."); 135 return(0); 136 } 137 doskipclean = 0; 138 pwarn("USING ALTERNATE SUPERBLOCK AT %d\n", bflag); 139 } 140 if (debug) 141 printf("state = %d\n", sblock.e2fs.e2fs_state); 142 if (sblock.e2fs.e2fs_state == E2FS_ISCLEAN) { 143 if (doskipclean) { 144 pwarn("%sile system is clean; not checking\n", 145 preen ? "f" : "** F"); 146 return (-1); 147 } 148 if (!preen) 149 pwarn("** File system is already clean\n"); 150 } 151 maxfsblock = sblock.e2fs.e2fs_bcount; 152 maxino = sblock.e2fs_ncg * sblock.e2fs.e2fs_ipg; 153 sizepb = sblock.e2fs_bsize; 154 maxfilesize = sblock.e2fs_bsize * NDADDR - 1; 155 for (i = 0; i < NIADDR; i++) { 156 sizepb *= NINDIR(&sblock); 157 maxfilesize += sizepb; 158 } 159 /* 160 * Check and potentially fix certain fields in the super block. 161 */ 162 if ((sblock.e2fs.e2fs_rbcount < 0) || 163 (sblock.e2fs.e2fs_rbcount > sblock.e2fs.e2fs_bcount)) { 164 pfatal("IMPOSSIBLE RESERVED BLOCK COUNT=%d IN SUPERBLOCK", 165 sblock.e2fs.e2fs_rbcount); 166 if (reply("SET TO DEFAULT") == 1) { 167 sblock.e2fs.e2fs_rbcount = sblock.e2fs.e2fs_bcount * 0.1; 168 sbdirty(); 169 dirty(&asblk); 170 } 171 } 172 if (sblock.e2fs.e2fs_bpg != sblock.e2fs.e2fs_fpg) { 173 pfatal("WRONG FPG=%d (BPG=%d) IN SUPERBLOCK", 174 sblock.e2fs.e2fs_fpg, sblock.e2fs.e2fs_bpg); 175 return 0; 176 } 177 if (asblk.b_dirty && !bflag) { 178 copyback_sb(&asblk); 179 flush(fswritefd, &asblk); 180 } 181 /* 182 * read in the summary info. 183 */ 184 185 sblock.e2fs_gd = calloc(sblock.e2fs_ngdb, sblock.e2fs_bsize); 186 if (sblock.e2fs_gd == NULL) 187 errexit("out of memory\n"); 188 asked = 0; 189 for (i=0; i < sblock.e2fs_ngdb; i++) { 190 if (bread(fsreadfd,(char *) 191 &sblock.e2fs_gd[i* sblock.e2fs_bsize / sizeof(struct ext2_gd)], 192 fsbtodb(&sblock, ((sblock.e2fs_bsize>1024)?0:1)+i+1), 193 sblock.e2fs_bsize) != 0 && !asked) { 194 pfatal("BAD SUMMARY INFORMATION"); 195 if (reply("CONTINUE") == 0) 196 errexit("%s\n", ""); 197 asked++; 198 } 199 } 200 /* 201 * allocate and initialize the necessary maps 202 */ 203 bmapsize = roundup(howmany(maxfsblock, NBBY), sizeof(int16_t)); 204 blockmap = calloc((unsigned)bmapsize, sizeof (char)); 205 if (blockmap == NULL) { 206 printf("cannot alloc %u bytes for blockmap\n", 207 (unsigned)bmapsize); 208 goto badsblabel; 209 } 210 statemap = calloc((unsigned)(maxino + 2), sizeof(char)); 211 if (statemap == NULL) { 212 printf("cannot alloc %u bytes for statemap\n", 213 (unsigned)(maxino + 1)); 214 goto badsblabel; 215 } 216 typemap = calloc((unsigned)(maxino + 1), sizeof(char)); 217 if (typemap == NULL) { 218 printf("cannot alloc %u bytes for typemap\n", 219 (unsigned)(maxino + 1)); 220 goto badsblabel; 221 } 222 lncntp = (int16_t *)calloc((unsigned)(maxino + 1), sizeof(int16_t)); 223 if (lncntp == NULL) { 224 printf("cannot alloc %u bytes for lncntp\n", 225 (unsigned)((maxino + 1) * sizeof(int16_t))); 226 goto badsblabel; 227 } 228 for (numdirs = 0, cg = 0; cg < sblock.e2fs_ncg; cg++) { 229 numdirs += fs2h16(sblock.e2fs_gd[cg].ext2bgd_ndirs); 230 } 231 inplast = 0; 232 listmax = numdirs + 10; 233 inpsort = (struct inoinfo **)calloc((unsigned)listmax, 234 sizeof(struct inoinfo *)); 235 inphead = (struct inoinfo **)calloc((unsigned)numdirs, 236 sizeof(struct inoinfo *)); 237 if (inpsort == NULL || inphead == NULL) { 238 printf("cannot alloc %u bytes for inphead\n", 239 (unsigned)(numdirs * sizeof(struct inoinfo *))); 240 goto badsblabel; 241 } 242 bufinit(); 243 return (1); 244 245 badsblabel: 246 ckfini(0); 247 return (0); 248 } 249 250 /* 251 * Read in the super block and its summary info. 252 */ 253 static int 254 readsb(int listerr) 255 { 256 daddr32_t super = bflag ? bflag : SBOFF / dev_bsize; 257 258 if (bread(fsreadfd, (char *)sblk.b_un.b_fs, super, (long)SBSIZE) != 0) 259 return (0); 260 sblk.b_bno = super; 261 sblk.b_size = SBSIZE; 262 263 /* Copy the superblock in memory */ 264 e2fs_sbload(sblk.b_un.b_fs, &sblock.e2fs); 265 266 /* 267 * run a few consistency checks of the super block 268 */ 269 if (sblock.e2fs.e2fs_magic != E2FS_MAGIC) { 270 badsb(listerr, "MAGIC NUMBER WRONG"); return (0); 271 } 272 if (sblock.e2fs.e2fs_log_bsize > 2) { 273 badsb(listerr, "BAD LOG_BSIZE"); return (0); 274 } 275 276 /* compute the dynamic fields of the in-memory sb */ 277 /* compute dynamic sb infos */ 278 sblock.e2fs_ncg = 279 howmany(sblock.e2fs.e2fs_bcount - sblock.e2fs.e2fs_first_dblock, 280 sblock.e2fs.e2fs_bpg); 281 /* XXX assume hw bsize = 512 */ 282 sblock.e2fs_fsbtodb = sblock.e2fs.e2fs_log_bsize + 1; 283 sblock.e2fs_bsize = 1024 << sblock.e2fs.e2fs_log_bsize; 284 sblock.e2fs_bshift = LOG_MINBSIZE + sblock.e2fs.e2fs_log_bsize; 285 sblock.e2fs_qbmask = sblock.e2fs_bsize - 1; 286 sblock.e2fs_bmask = ~sblock.e2fs_qbmask; 287 sblock.e2fs_ngdb = howmany(sblock.e2fs_ncg, 288 sblock.e2fs_bsize / sizeof(struct ext2_gd)); 289 sblock.e2fs_ipb = sblock.e2fs_bsize / sizeof(struct ext2fs_dinode); 290 sblock.e2fs_itpg = sblock.e2fs.e2fs_ipg/sblock.e2fs_ipb; 291 292 /* 293 * Compute block size that the filesystem is based on, 294 * according to fsbtodb, and adjust superblock block number 295 * so we can tell if this is an alternate later. 296 */ 297 super *= dev_bsize; 298 dev_bsize = sblock.e2fs_bsize / fsbtodb(&sblock, 1); 299 sblk.b_bno = super / dev_bsize; 300 301 if (sblock.e2fs_ncg == 1) { 302 /* no alternate superblock; assume it's okey */ 303 havesb = 1; 304 return 1; 305 } 306 307 getblk(&asblk, 1 * sblock.e2fs.e2fs_bpg + sblock.e2fs.e2fs_first_dblock, 308 (long)SBSIZE); 309 if (asblk.b_errs) 310 return (0); 311 if (bflag) { 312 havesb = 1; 313 return (1); 314 } 315 316 /* 317 * Set all possible fields that could differ, then do check 318 * of whole super block against an alternate super block. 319 * When an alternate super-block is specified this check is skipped. 320 */ 321 asblk.b_un.b_fs->e2fs_rbcount = sblk.b_un.b_fs->e2fs_rbcount; 322 asblk.b_un.b_fs->e2fs_fbcount = sblk.b_un.b_fs->e2fs_fbcount; 323 asblk.b_un.b_fs->e2fs_ficount = sblk.b_un.b_fs->e2fs_ficount; 324 asblk.b_un.b_fs->e2fs_mtime = sblk.b_un.b_fs->e2fs_mtime; 325 asblk.b_un.b_fs->e2fs_wtime = sblk.b_un.b_fs->e2fs_wtime; 326 asblk.b_un.b_fs->e2fs_mnt_count = sblk.b_un.b_fs->e2fs_mnt_count; 327 asblk.b_un.b_fs->e2fs_max_mnt_count = sblk.b_un.b_fs->e2fs_max_mnt_count; 328 asblk.b_un.b_fs->e2fs_state = sblk.b_un.b_fs->e2fs_state; 329 asblk.b_un.b_fs->e2fs_beh = sblk.b_un.b_fs->e2fs_beh; 330 asblk.b_un.b_fs->e2fs_lastfsck = sblk.b_un.b_fs->e2fs_lastfsck; 331 asblk.b_un.b_fs->e2fs_fsckintv = sblk.b_un.b_fs->e2fs_fsckintv; 332 asblk.b_un.b_fs->e2fs_ruid = sblk.b_un.b_fs->e2fs_ruid; 333 asblk.b_un.b_fs->e2fs_rgid = sblk.b_un.b_fs->e2fs_rgid; 334 asblk.b_un.b_fs->e2fs_block_group_nr = 335 sblk.b_un.b_fs->e2fs_block_group_nr; 336 asblk.b_un.b_fs->e2fs_features_rocompat &= ~EXT2F_ROCOMPAT_LARGEFILE; 337 asblk.b_un.b_fs->e2fs_features_rocompat |= 338 sblk.b_un.b_fs->e2fs_features_rocompat & EXT2F_ROCOMPAT_LARGEFILE; 339 if (sblock.e2fs.e2fs_rev > E2FS_REV0 && 340 ((sblock.e2fs.e2fs_features_incompat & ~EXT2F_INCOMPAT_SUPP) || 341 (sblock.e2fs.e2fs_features_rocompat & ~EXT2F_ROCOMPAT_SUPP))) { 342 if (debug) { 343 printf("compat 0x%08x, incompat 0x%08x, compat_ro " 344 "0x%08x\n", 345 sblock.e2fs.e2fs_features_compat, 346 sblock.e2fs.e2fs_features_incompat, 347 sblock.e2fs.e2fs_features_rocompat); 348 } 349 badsb(listerr,"INCOMPATIBLE FEATURE BITS IN SUPER BLOCK"); 350 return 0; 351 } 352 if (memcmp(sblk.b_un.b_fs, asblk.b_un.b_fs, SBSIZE)) { 353 if (debug) { 354 u_int32_t *nlp, *olp, *endlp; 355 356 printf("superblock mismatches\n"); 357 nlp = (u_int32_t *)asblk.b_un.b_fs; 358 olp = (u_int32_t *)sblk.b_un.b_fs; 359 endlp = olp + (SBSIZE / sizeof *olp); 360 for ( ; olp < endlp; olp++, nlp++) { 361 if (*olp == *nlp) 362 continue; 363 printf("offset %ld, original %ld, alternate %ld\n", 364 (long)(olp - (u_int32_t *)sblk.b_un.b_fs), 365 (long)fs2h32(*olp), 366 (long)fs2h32(*nlp)); 367 } 368 } 369 badsb(listerr, 370 "VALUES IN SUPER BLOCK DISAGREE WITH THOSE IN FIRST ALTERNATE"); 371 return (0); 372 } 373 havesb = 1; 374 return (1); 375 } 376 377 void 378 copyback_sb(struct bufarea *bp) 379 { 380 /* Copy the in-memory superblock back to buffer */ 381 bp->b_un.b_fs->e2fs_icount = fs2h32(sblock.e2fs.e2fs_icount); 382 bp->b_un.b_fs->e2fs_bcount = fs2h32(sblock.e2fs.e2fs_bcount); 383 bp->b_un.b_fs->e2fs_rbcount = fs2h32(sblock.e2fs.e2fs_rbcount); 384 bp->b_un.b_fs->e2fs_fbcount = fs2h32(sblock.e2fs.e2fs_fbcount); 385 bp->b_un.b_fs->e2fs_ficount = fs2h32(sblock.e2fs.e2fs_ficount); 386 bp->b_un.b_fs->e2fs_first_dblock = 387 fs2h32(sblock.e2fs.e2fs_first_dblock); 388 bp->b_un.b_fs->e2fs_log_bsize = fs2h32(sblock.e2fs.e2fs_log_bsize); 389 bp->b_un.b_fs->e2fs_fsize = fs2h32(sblock.e2fs.e2fs_fsize); 390 bp->b_un.b_fs->e2fs_bpg = fs2h32(sblock.e2fs.e2fs_bpg); 391 bp->b_un.b_fs->e2fs_fpg = fs2h32(sblock.e2fs.e2fs_fpg); 392 bp->b_un.b_fs->e2fs_ipg = fs2h32(sblock.e2fs.e2fs_ipg); 393 bp->b_un.b_fs->e2fs_mtime = fs2h32(sblock.e2fs.e2fs_mtime); 394 bp->b_un.b_fs->e2fs_wtime = fs2h32(sblock.e2fs.e2fs_wtime); 395 bp->b_un.b_fs->e2fs_lastfsck = fs2h32(sblock.e2fs.e2fs_lastfsck); 396 bp->b_un.b_fs->e2fs_fsckintv = fs2h32(sblock.e2fs.e2fs_fsckintv); 397 bp->b_un.b_fs->e2fs_creator = fs2h32(sblock.e2fs.e2fs_creator); 398 bp->b_un.b_fs->e2fs_rev = fs2h32(sblock.e2fs.e2fs_rev); 399 bp->b_un.b_fs->e2fs_mnt_count = fs2h16(sblock.e2fs.e2fs_mnt_count); 400 bp->b_un.b_fs->e2fs_max_mnt_count = 401 fs2h16(sblock.e2fs.e2fs_max_mnt_count); 402 bp->b_un.b_fs->e2fs_magic = fs2h16(sblock.e2fs.e2fs_magic); 403 bp->b_un.b_fs->e2fs_state = fs2h16(sblock.e2fs.e2fs_state); 404 bp->b_un.b_fs->e2fs_beh = fs2h16(sblock.e2fs.e2fs_beh); 405 bp->b_un.b_fs->e2fs_ruid = fs2h16(sblock.e2fs.e2fs_ruid); 406 bp->b_un.b_fs->e2fs_rgid = fs2h16(sblock.e2fs.e2fs_rgid); 407 } 408 409 void 410 badsb(int listerr, char *s) 411 { 412 413 if (!listerr) 414 return; 415 if (preen) 416 printf("%s: ", cdevname()); 417 pfatal("BAD SUPER BLOCK: %s\n", s); 418 } 419 420 /* 421 * Calculate a prototype superblock based on information in the disk label. 422 * When done the cgsblock macro can be calculated and the fs_ncg field 423 * can be used. Do NOT attempt to use other macros without verifying that 424 * their needed information is available! 425 */ 426 427 int 428 calcsb(char *dev, int devfd, struct m_ext2fs *fs) 429 { 430 struct disklabel *lp; 431 struct partition *pp; 432 char *cp; 433 434 cp = strchr(dev, '\0') - 1; 435 if ((cp == (char *)-1 || (*cp < 'a' || *cp > 'h')) && !isdigit(*cp)) { 436 pfatal("%s: CANNOT FIGURE OUT FILE SYSTEM PARTITION\n", dev); 437 return (0); 438 } 439 lp = getdisklabel(dev, devfd); 440 if (isdigit(*cp)) 441 pp = &lp->d_partitions[0]; 442 else 443 pp = &lp->d_partitions[*cp - 'a']; 444 if (pp->p_fstype != FS_EXT2FS) { 445 pfatal("%s: NOT LABELED AS A EXT2 FILE SYSTEM (%s)\n", 446 dev, pp->p_fstype < FSMAXTYPES ? 447 fstypenames[pp->p_fstype] : "unknown"); 448 return (0); 449 } 450 memset(fs, 0, sizeof(struct m_ext2fs)); 451 fs->e2fs_bsize = DISKLABELV1_FFS_FSIZE(pp->p_fragblock); /* XXX */ 452 fs->e2fs.e2fs_log_bsize = fs->e2fs_bsize / 1024; 453 fs->e2fs.e2fs_bcount = (pp->p_size * DEV_BSIZE) / fs->e2fs_bsize; 454 fs->e2fs.e2fs_first_dblock = (fs->e2fs.e2fs_log_bsize == 0) ? 1 : 0; 455 fs->e2fs.e2fs_bpg = fs->e2fs_bsize * NBBY; 456 fs->e2fs_bshift = LOG_MINBSIZE + fs->e2fs.e2fs_log_bsize; 457 fs->e2fs_qbmask = fs->e2fs_bsize - 1; 458 fs->e2fs_bmask = ~fs->e2fs_qbmask; 459 fs->e2fs_ncg = 460 howmany(fs->e2fs.e2fs_bcount - fs->e2fs.e2fs_first_dblock, 461 fs->e2fs.e2fs_bpg); 462 fs->e2fs_fsbtodb = fs->e2fs.e2fs_log_bsize + 1; 463 fs->e2fs_ngdb = howmany(fs->e2fs_ncg, 464 fs->e2fs_bsize / sizeof(struct ext2_gd)); 465 466 return (1); 467 } 468 469 static struct disklabel * 470 getdisklabel(char *s, int fd) 471 { 472 static struct disklabel lab; 473 474 if (ioctl(fd, DIOCGDINFO, (char *)&lab) < 0) { 475 if (s == NULL) 476 return ((struct disklabel *)NULL); 477 pwarn("ioctl (GCINFO): %s\n", strerror(errno)); 478 errexit("%s: can't read disk label\n", s); 479 } 480 return (&lab); 481 } 482 483 daddr32_t 484 cgoverhead(int c) 485 { 486 int overh; 487 overh = 1 /* block bitmap */ + 488 1 /* inode bitmap */ + 489 sblock.e2fs_itpg; 490 if (sblock.e2fs.e2fs_rev > E2FS_REV0 && 491 sblock.e2fs.e2fs_features_rocompat & EXT2F_ROCOMPAT_SPARSESUPER) { 492 if (cg_has_sb(c) == 0) 493 return overh; 494 } 495 overh += 1 + sblock.e2fs_ngdb; 496 return overh; 497 } 498