xref: /freebsd/sbin/fsck_ffs/setup.c (revision b679303544b37b980a3128af9248ee97b0bca5e8)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1980, 1986, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/param.h>
33 #include <sys/disk.h>
34 #include <sys/stat.h>
35 #define FSTYPENAMES
36 #include <sys/disklabel.h>
37 #include <sys/file.h>
38 #include <sys/sysctl.h>
39 
40 #include <ufs/ufs/dinode.h>
41 #include <ufs/ffs/fs.h>
42 
43 #include <ctype.h>
44 #include <err.h>
45 #include <errno.h>
46 #include <limits.h>
47 #include <stdint.h>
48 #include <string.h>
49 
50 #include "fsck.h"
51 
52 struct inohash *inphash;	       /* hash list of directory inode info */
53 struct inoinfo **inpsort;	       /* disk order list of directory inodes */
54 struct inode snaplist[FSMAXSNAP + 1];  /* list of active snapshots */
55 int snapcnt;			       /* number of active snapshots */
56 char *copybuf;			       /* buffer to copy snapshot blocks */
57 
58 static int sbhashfailed;
59 #define POWEROF2(num)	(((num) & ((num) - 1)) == 0)
60 
61 static void saverecovery(int readfd, int writefd);
62 static int chkrecovery(int devfd);
63 static int getlbnblkno(struct inodesc *);
64 static int checksnapinfo(struct inode *);
65 
66 /*
67  * Read in a superblock finding an alternate if necessary.
68  * Return 1 if successful, 0 if unsuccessful, -1 if file system
69  * is already clean (ckclean and preen mode only).
70  */
71 int
setup(char * dev)72 setup(char *dev)
73 {
74 	long i, bmapsize;
75 	struct inode ip;
76 
77 	/*
78 	 * We are expected to have an open file descriptor and a superblock.
79 	 */
80 	if (fsreadfd < 0 || havesb == 0) {
81 		if (debug) {
82 			if (fsreadfd < 0)
83 				printf("setup: missing fsreadfd\n");
84 			else
85 				printf("setup: missing superblock\n");
86 		}
87 		return (0);
88 	}
89 	if (preen == 0)
90 		printf("** %s", dev);
91 	if (bkgrdflag == 0 &&
92 	    (nflag || (fswritefd = open(dev, O_WRONLY)) < 0)) {
93 		fswritefd = -1;
94 		if (preen)
95 			pfatal("NO WRITE ACCESS");
96 		printf(" (NO WRITE)");
97 	}
98 	if (preen == 0)
99 		printf("\n");
100 	if (sbhashfailed != 0) {
101 		pwarn("SUPERBLOCK CHECK HASH FAILED");
102 		if (fswritefd == -1)
103 			pwarn("OPENED READONLY SO CANNOT CORRECT CHECK HASH\n");
104 		else if (preen || reply("CORRECT CHECK HASH") != 0) {
105 			if (preen)
106 				printf(" (CORRECTED)\n");
107 			sblock.fs_clean = 0;
108 			sbdirty();
109 		}
110 	}
111 	if (skipclean && ckclean && sblock.fs_clean) {
112 		pwarn("FILE SYSTEM CLEAN; SKIPPING CHECKS\n");
113 		return (-1);
114 	}
115 	maxfsblock = sblock.fs_size;
116 	maxino = sblock.fs_ncg * sblock.fs_ipg;
117 	/*
118 	 * Check and potentially fix certain fields in the super block.
119 	 */
120 	if (sblock.fs_optim != FS_OPTTIME && sblock.fs_optim != FS_OPTSPACE) {
121 		pfatal("UNDEFINED OPTIMIZATION IN SUPERBLOCK");
122 		if (reply("SET TO DEFAULT") == 1) {
123 			sblock.fs_optim = FS_OPTTIME;
124 			sbdirty();
125 		}
126 	}
127 	if ((sblock.fs_minfree < 0 || sblock.fs_minfree > 99)) {
128 		pfatal("IMPOSSIBLE MINFREE=%d IN SUPERBLOCK",
129 			sblock.fs_minfree);
130 		if (reply("SET TO DEFAULT") == 1) {
131 			sblock.fs_minfree = 10;
132 			sbdirty();
133 		}
134 	}
135 	if (sblock.fs_magic == FS_UFS1_MAGIC &&
136 	    sblock.fs_old_inodefmt < FS_44INODEFMT) {
137 		pwarn("Format of file system is too old.\n");
138 		pwarn("Must update to modern format using a version of fsck\n");
139 		pfatal("from before 2002 with the command ``fsck -c 2''\n");
140 		exit(EEXIT);
141 	}
142 	if (preen == 0 && yflag == 0 && sblock.fs_magic == FS_UFS2_MAGIC &&
143 	    fswritefd != -1 && chkrecovery(fsreadfd) == 0 &&
144 	    reply("SAVE DATA TO FIND ALTERNATE SUPERBLOCKS") != 0)
145 		saverecovery(fsreadfd, fswritefd);
146 	/*
147 	 * allocate and initialize the necessary maps
148 	 */
149 	bufinit();
150 	bmapsize = roundup(howmany(maxfsblock, CHAR_BIT), sizeof(short));
151 	blockmap = Calloc((unsigned)bmapsize, sizeof (char));
152 	if (blockmap == NULL) {
153 		printf("cannot alloc %u bytes for blockmap\n",
154 		    (unsigned)bmapsize);
155 		goto badsb;
156 	}
157 	inostathead = Calloc(sblock.fs_ncg, sizeof(struct inostatlist));
158 	if (inostathead == NULL) {
159 		printf("cannot alloc %u bytes for inostathead\n",
160 		    (unsigned)(sizeof(struct inostatlist) * (sblock.fs_ncg)));
161 		goto badsb;
162 	}
163 	numdirs = sblock.fs_cstotal.cs_ndir;
164 	dirhash = MAX(numdirs / 2, 1);
165 	inplast = 0;
166 	listmax = numdirs + 10;
167 	inpsort = (struct inoinfo **)Calloc(listmax, sizeof(struct inoinfo *));
168 	inphash = (struct inohash *)Calloc(dirhash, sizeof(struct inohash));
169 	if (inpsort == NULL || inphash == NULL) {
170 		printf("cannot alloc %ju bytes for inphash\n",
171 		    (uintmax_t)numdirs * sizeof(struct inoinfo *));
172 		goto badsb;
173 	}
174 	if (sblock.fs_flags & FS_DOSOFTDEP)
175 		usedsoftdep = 1;
176 	else
177 		usedsoftdep = 0;
178 	/*
179 	 * Collect any snapshot inodes so that we can allow them to
180 	 * claim any blocks that we free. The code for doing this is
181 	 * imported here and into inode.c from sys/ufs/ffs/ffs_snapshot.c.
182 	 */
183 	for (snapcnt = 0; snapcnt < FSMAXSNAP; snapcnt++) {
184 		if (sblock.fs_snapinum[snapcnt] == 0)
185 			break;
186 		ginode(sblock.fs_snapinum[snapcnt], &ip);
187 		if ((DIP(ip.i_dp, di_mode) & IFMT) == IFREG &&
188 		    (DIP(ip.i_dp, di_flags) & SF_SNAPSHOT) != 0 &&
189 		    checksnapinfo(&ip)) {
190 			if (debug)
191 				printf("Load snapshot %jd\n",
192 				    (intmax_t)sblock.fs_snapinum[snapcnt]);
193 			snaplist[snapcnt] = ip;
194 			continue;
195 		}
196 		printf("Removing non-snapshot inode %ju from snapshot list\n",
197 		    (uintmax_t)sblock.fs_snapinum[snapcnt]);
198 		irelse(&ip);
199 		for (i = snapcnt + 1; i < FSMAXSNAP; i++) {
200 			if (sblock.fs_snapinum[i] == 0)
201 				break;
202 			sblock.fs_snapinum[i - 1] = sblock.fs_snapinum[i];
203 		}
204 		sblock.fs_snapinum[i - 1] = 0;
205 		snapcnt--;
206 		sbdirty();
207 	}
208 	if (snapcnt > 0 && copybuf == NULL) {
209 		copybuf = Balloc(sblock.fs_bsize);
210 		if (copybuf == NULL)
211 			errx(EEXIT, "cannot allocate space for snapshot "
212 			    "copy buffer");
213 	}
214 	return (1);
215 
216 badsb:
217 	ckfini(0);
218 	return (0);
219 }
220 
221 /*
222  * Check for valid snapshot information.
223  *
224  * Each snapshot has a list of blocks that have been copied. This list
225  * is consulted before checking the snapshot inode. Its purpose is to
226  * speed checking of commonly checked blocks and to avoid recursive
227  * checks of the snapshot inode. In particular, the list must contain
228  * the superblock, the superblock summary information, and all the
229  * cylinder group blocks. The list may contain other commonly checked
230  * pointers such as those of the blocks that contain the snapshot inodes.
231  * The list is sorted into block order to allow binary search lookup.
232  *
233  * The twelve direct direct block pointers of the snapshot are always
234  * copied, so we test for them first before checking the list itself
235  * (i.e., they are not in the list).
236  *
237  * The checksnapinfo() routine needs to ensure that the list contains at
238  * least the super block, its summary information, and the cylinder groups.
239  * Here we check the list first for the superblock, zero or more cylinder
240  * groups up to the location of the superblock summary information, the
241  * summary group information, and any remaining cylinder group maps that
242  * follow it. We skip over any other entries in the list.
243  */
244 #define CHKBLKINLIST(chkblk)						\
245 	/* All UFS_NDADDR blocks are copied */				\
246 	if ((chkblk) >= UFS_NDADDR) {					\
247 		/* Skip over blocks that are not of interest */		\
248 		while (*blkp < (chkblk) && blkp < lastblkp)		\
249 			blkp++;						\
250 		/* Fail if end of list and not all blocks found */	\
251 		if (blkp >= lastblkp) {					\
252 			pwarn("UFS%d snapshot inode %jd failed: "	\
253 			    "improper block list length (%jd)\n",	\
254 			    sblock.fs_magic == FS_UFS1_MAGIC ? 1 : 2,	\
255 			    (intmax_t)snapip->i_number,			\
256 			    (intmax_t)(lastblkp - &snapblklist[0]));	\
257 			status = 0;					\
258 		}							\
259 		/* Fail if block we seek is missing */			\
260 		else if (*blkp++ != (chkblk)) {				\
261 			pwarn("UFS%d snapshot inode %jd failed: "	\
262 			    "block list (%jd) != %s (%jd)\n",		\
263 			    sblock.fs_magic == FS_UFS1_MAGIC ? 1 : 2,	\
264 			    (intmax_t)snapip->i_number,			\
265 			    (intmax_t)blkp[-1],	#chkblk,		\
266 			    (intmax_t)chkblk);				\
267 			status = 0;					\
268 		}							\
269 	}
270 
271 static int
checksnapinfo(struct inode * snapip)272 checksnapinfo(struct inode *snapip)
273 {
274 	struct fs *fs;
275 	struct bufarea *bp;
276 	struct inodesc idesc;
277 	daddr_t *snapblklist, *blkp, *lastblkp, csblkno;
278 	int cg, loc, len, status;
279 	ufs_lbn_t lbn;
280 	size_t size;
281 
282 	fs = &sblock;
283 	memset(&idesc, 0, sizeof(struct inodesc));
284 	idesc.id_type = ADDR;
285 	idesc.id_func = getlbnblkno;
286 	idesc.id_number = snapip->i_number;
287 	lbn = howmany(fs->fs_size, fs->fs_frag);
288 	idesc.id_parent = lbn;		/* sought after blkno */
289 	if ((ckinode(snapip->i_dp, &idesc) & FOUND) == 0)
290 		return (0);
291 	size = fragroundup(fs,
292 	    DIP(snapip->i_dp, di_size) - lblktosize(fs, lbn));
293 	bp = getdatablk(idesc.id_parent, size, BT_DATA);
294 	if (bp->b_errs != 0)
295 		return (0);
296 	snapblklist = (daddr_t *)bp->b_un.b_buf;
297 	/*
298 	 * snapblklist[0] is the size of the list
299 	 * snapblklist[1] is the first element of the list
300 	 *
301 	 * We need to be careful to bound the size of the list and verify
302 	 * that we have not run off the end of it if it or its size has
303 	 * been corrupted.
304 	 */
305 	blkp = &snapblklist[1];
306 	lastblkp = &snapblklist[MAX(0,
307 	    MIN(snapblklist[0] + 1, size / sizeof(daddr_t)))];
308 	status = 1;
309 	/* Check that the superblock is listed. */
310 	CHKBLKINLIST(lblkno(fs, fs->fs_sblockloc));
311 	if (status == 0)
312 		goto out;
313 	/*
314 	 * Calculate where the summary information is located.
315 	 * Usually it is in the first cylinder group, but growfs
316 	 * may move it to the first cylinder group that it adds.
317 	 *
318 	 * Check all cylinder groups up to the summary information.
319 	 */
320 	csblkno = fragstoblks(fs, fs->fs_csaddr);
321 	for (cg = 0; cg < fs->fs_ncg; cg++) {
322 		if (fragstoblks(fs, cgtod(fs, cg)) > csblkno)
323 			break;
324 		CHKBLKINLIST(fragstoblks(fs, cgtod(fs, cg)));
325 		if (status == 0)
326 			goto out;
327 	}
328 	/* Check the summary information block(s). */
329 	len = howmany(fs->fs_cssize, fs->fs_bsize);
330 	for (loc = 0; loc < len; loc++) {
331 		CHKBLKINLIST(csblkno + loc);
332 		if (status == 0)
333 			goto out;
334 	}
335 	/* Check the remaining cylinder groups. */
336 	for (; cg < fs->fs_ncg; cg++) {
337 		CHKBLKINLIST(fragstoblks(fs, cgtod(fs, cg)));
338 		if (status == 0)
339 			goto out;
340 	}
341 out:
342 	brelse(bp);
343 	return (status);
344 }
345 
346 /*
347  * Return the block number associated with a specified inode lbn.
348  * Requested lbn is in id_parent. If found, block is returned in
349  * id_parent.
350  */
351 static int
getlbnblkno(struct inodesc * idesc)352 getlbnblkno(struct inodesc *idesc)
353 {
354 
355 	if (idesc->id_lbn < idesc->id_parent)
356 		return (KEEPON);
357 	idesc->id_parent = idesc->id_blkno;
358 	return (STOP | FOUND);
359 }
360 
361 /*
362  * Open a device or file to be checked by fsck.
363  */
364 int
openfilesys(char * dev)365 openfilesys(char *dev)
366 {
367 	struct stat statb;
368 	int saved_fsreadfd;
369 
370 	if (stat(dev, &statb) < 0)
371 		return (0);
372 	if ((statb.st_mode & S_IFMT) != S_IFCHR &&
373 	    (statb.st_mode & S_IFMT) != S_IFBLK) {
374 		if (bkgrdflag != 0 && (statb.st_flags & SF_SNAPSHOT) == 0) {
375 			pwarn("BACKGROUND FSCK LACKS A SNAPSHOT\n");
376 			return (0);
377 		}
378 		if (bkgrdflag != 0) {
379 			cursnapshot = statb.st_ino;
380 		} else {
381 			pwarn("%s IS NOT A DISK DEVICE\n", dev);
382 			if (preen || reply("CONTINUE") == 0)
383 				return (0);
384 		}
385 	}
386 	saved_fsreadfd = fsreadfd;
387 	if ((fsreadfd = open(dev, O_RDONLY)) < 0) {
388 		fsreadfd = saved_fsreadfd;
389 		return (0);
390 	}
391 	if (saved_fsreadfd != -1)
392 		close(saved_fsreadfd);
393 	return (1);
394 }
395 
396 /*
397  * Read in the super block and its summary info.
398  */
399 int
readsb(void)400 readsb(void)
401 {
402 	struct fs *fs;
403 
404 	sbhashfailed = 0;
405 	readcnt[sblk.b_type]++;
406 	/*
407 	 * If bflag is given, then check just that superblock.
408 	 */
409 	if (bflag) {
410 		switch (sbget(fsreadfd, &fs, bflag * dev_bsize, 0)) {
411 		case 0:
412 			goto goodsb;
413 		case EINTEGRITY:
414 			printf("Check hash failed for superblock at %jd\n",
415 			    bflag);
416 			return (0);
417 		case ENOENT:
418 			printf("%jd is not a file system superblock\n", bflag);
419 			return (0);
420 		case EIO:
421 		default:
422 			printf("I/O error reading %jd\n", bflag);
423 			return (0);
424 		}
425 	}
426 	/*
427 	 * Check for the standard superblock and use it if good.
428 	 */
429 	if (sbget(fsreadfd, &fs, UFS_STDSB, UFS_NOMSG) == 0)
430 		goto goodsb;
431 	/*
432 	 * Check if the only problem is a check-hash failure.
433 	 */
434 	skipclean = 0;
435 	if (sbget(fsreadfd, &fs, UFS_STDSB, UFS_NOMSG | UFS_NOHASHFAIL) == 0) {
436 		sbhashfailed = 1;
437 		goto goodsb;
438 	}
439 	/*
440 	 * Do an exhaustive search for a usable superblock.
441 	 */
442 	switch (sbsearch(fsreadfd, &fs, 0)) {
443 	case 0:
444 		goto goodsb;
445 	case ENOENT:
446 		printf("SEARCH FOR ALTERNATE SUPER-BLOCK FAILED. "
447 		    "YOU MUST USE THE\n-b OPTION TO FSCK TO SPECIFY "
448 		    "THE LOCATION OF AN ALTERNATE\nSUPER-BLOCK TO "
449 		    "SUPPLY NEEDED INFORMATION; SEE fsck_ffs(8).\n");
450 		return (0);
451 	case EIO:
452 	default:
453 		printf("I/O error reading a usable superblock\n");
454 		return (0);
455 	}
456 
457 goodsb:
458 	memcpy(&sblock, fs, fs->fs_sbsize);
459 	free(fs);
460 	/*
461 	 * Compute block size that the file system is based on,
462 	 * according to fsbtodb, and adjust superblock block number
463 	 * so we can tell if this is an alternate later.
464 	 */
465 	dev_bsize = sblock.fs_fsize / fsbtodb(&sblock, 1);
466 	sblk.b_bno = sblock.fs_sblockactualloc / dev_bsize;
467 	sblk.b_size = SBLOCKSIZE;
468 	/*
469 	 * If not yet done, update UFS1 superblock with new wider fields.
470 	 */
471 	if (sblock.fs_magic == FS_UFS1_MAGIC &&
472 	    sblock.fs_maxbsize != sblock.fs_bsize) {
473 		sblock.fs_maxbsize = sblock.fs_bsize;
474 		sblock.fs_time = sblock.fs_old_time;
475 		sblock.fs_size = sblock.fs_old_size;
476 		sblock.fs_dsize = sblock.fs_old_dsize;
477 		sblock.fs_csaddr = sblock.fs_old_csaddr;
478 		sblock.fs_cstotal.cs_ndir = sblock.fs_old_cstotal.cs_ndir;
479 		sblock.fs_cstotal.cs_nbfree = sblock.fs_old_cstotal.cs_nbfree;
480 		sblock.fs_cstotal.cs_nifree = sblock.fs_old_cstotal.cs_nifree;
481 		sblock.fs_cstotal.cs_nffree = sblock.fs_old_cstotal.cs_nffree;
482 	}
483 	havesb = 1;
484 	return (1);
485 }
486 
487 void
sblock_init(void)488 sblock_init(void)
489 {
490 
491 	fsreadfd = -1;
492 	fswritefd = -1;
493 	fsmodified = 0;
494 	lfdir = 0;
495 	initbarea(&sblk, BT_SUPERBLK);
496 	sblk.b_un.b_buf = Balloc(SBLOCKSIZE);
497 	if (sblk.b_un.b_buf == NULL)
498 		errx(EEXIT, "cannot allocate space for superblock");
499 	dev_bsize = secsize = DEV_BSIZE;
500 }
501 
502 /*
503  * Check to see if recovery information exists.
504  * Return 1 if it exists or cannot be created.
505  * Return 0 if it does not exist and can be created.
506  */
507 static int
chkrecovery(int devfd)508 chkrecovery(int devfd)
509 {
510 	struct fsrecovery *fsr;
511 	char *fsrbuf;
512 	u_int secsize, rdsize;
513 
514 	/*
515 	 * Could not determine if backup material exists, so do not
516 	 * offer to create it.
517 	 */
518 	fsrbuf = NULL;
519 	rdsize = sblock.fs_fsize;
520 	if (ioctl(devfd, DIOCGSECTORSIZE, &secsize) == -1 ||
521 	    rdsize % secsize != 0 ||
522 	    (fsrbuf = Balloc(rdsize)) == NULL ||
523 	    blread(devfd, fsrbuf, (SBLOCK_UFS2 - rdsize) / dev_bsize,
524 	      rdsize) != 0) {
525 		free(fsrbuf);
526 		return (1);
527 	}
528 	/*
529 	 * Recovery material has already been created, so do not
530 	 * need to create it again.
531 	 */
532 	fsr = (struct fsrecovery *)&fsrbuf[rdsize - sizeof *fsr];
533 	if (fsr->fsr_magic == FS_UFS2_MAGIC) {
534 		free(fsrbuf);
535 		return (1);
536 	}
537 	/*
538 	 * Recovery material has not been created and can be if desired.
539 	 */
540 	free(fsrbuf);
541 	return (0);
542 }
543 
544 /*
545  * Read the last filesystem-size piece of the boot block, replace the
546  * last 20 bytes with the recovery information, then write it back.
547  * The recovery information only works for UFS2 filesystems.
548  */
549 static void
saverecovery(int readfd,int writefd)550 saverecovery(int readfd, int writefd)
551 {
552 	struct fsrecovery *fsr;
553 	char *fsrbuf;
554 	u_int secsize, rdsize;
555 
556 	fsrbuf = NULL;
557 	rdsize = sblock.fs_fsize;
558 	if (sblock.fs_magic != FS_UFS2_MAGIC ||
559 	    ioctl(readfd, DIOCGSECTORSIZE, &secsize) == -1 ||
560 	    rdsize % secsize != 0 ||
561 	    (fsrbuf = Balloc(rdsize)) == NULL ||
562 	    blread(readfd, fsrbuf, (SBLOCK_UFS2 - rdsize) / dev_bsize,
563 	      rdsize) != 0) {
564 		printf("RECOVERY DATA COULD NOT BE CREATED\n");
565 		free(fsrbuf);
566 		return;
567 	}
568 	fsr = (struct fsrecovery *)&fsrbuf[rdsize - sizeof *fsr];
569 	fsr->fsr_magic = sblock.fs_magic;
570 	fsr->fsr_fpg = sblock.fs_fpg;
571 	fsr->fsr_fsbtodb = sblock.fs_fsbtodb;
572 	fsr->fsr_sblkno = sblock.fs_sblkno;
573 	fsr->fsr_ncg = sblock.fs_ncg;
574 	blwrite(writefd, fsrbuf, (SBLOCK_UFS2 - rdsize) / dev_bsize, rdsize);
575 	free(fsrbuf);
576 }
577