xref: /freebsd/sbin/fsck_ffs/main.c (revision 38c63bdc46252d4d8cd313dff4183ec4546d26d9)
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 #define _WANT_P_OSREL
33 #include <sys/param.h>
34 #include <sys/file.h>
35 #include <sys/mount.h>
36 #include <sys/resource.h>
37 #include <sys/stat.h>
38 #include <sys/sysctl.h>
39 #include <sys/uio.h>
40 #include <sys/disklabel.h>
41 
42 #include <ufs/ufs/dinode.h>
43 #include <ufs/ffs/fs.h>
44 
45 #include <err.h>
46 #include <errno.h>
47 #include <fstab.h>
48 #include <grp.h>
49 #include <inttypes.h>
50 #include <mntopts.h>
51 #include <paths.h>
52 #include <stdint.h>
53 #include <string.h>
54 #include <time.h>
55 
56 #include "fsck.h"
57 
58 static int  restarts;
59 static char snapname[BUFSIZ];	/* when doing snapshots, the name of the file */
60 
61 static void usage(void) __dead2;
62 static intmax_t argtoimax(int flag, const char *req, const char *str, int base);
63 static int checkfilesys(char *filesys);
64 static int setup_bkgrdchk(struct statfs *mntp, int sbrdfailed, char **filesys);
65 
66 int
67 main(int argc, char *argv[])
68 {
69 	int ch;
70 	struct rlimit rlimit;
71 	struct itimerval itimerval;
72 	int fsret;
73 	int ret = 0;
74 
75 	sync();
76 	skipclean = 1;
77 	inoopt = 0;
78 	while ((ch = getopt(argc, argv, "b:Bc:CdEfFm:npRrSyZz")) != -1) {
79 		switch (ch) {
80 		case 'b':
81 			skipclean = 0;
82 			bflag = argtoimax('b', "number", optarg, 10);
83 			printf("Alternate super block location: %jd\n", bflag);
84 			break;
85 
86 		case 'B':
87 			bkgrdflag = 1;
88 			break;
89 
90 		case 'c':
91 			skipclean = 0;
92 			cvtlevel = argtoimax('c', "conversion level", optarg,
93 			    10);
94 			if (cvtlevel < 3)
95 				errx(EEXIT, "cannot do level %d conversion",
96 				    cvtlevel);
97 			break;
98 
99 		case 'd':
100 			debug++;
101 			break;
102 
103 		case 'E':
104 			Eflag++;
105 			break;
106 
107 		case 'f':
108 			skipclean = 0;
109 			break;
110 
111 		case 'F':
112 			bkgrdcheck = 1;
113 			break;
114 
115 		case 'm':
116 			lfmode = argtoimax('m', "mode", optarg, 8);
117 			if (lfmode &~ 07777)
118 				errx(EEXIT, "bad mode to -m: %o", lfmode);
119 			printf("** lost+found creation mode %o\n", lfmode);
120 			break;
121 
122 		case 'n':
123 			nflag++;
124 			yflag = 0;
125 			break;
126 
127 		case 'p':
128 			preen++;
129 			/*FALLTHROUGH*/
130 
131 		case 'C':
132 			ckclean++;
133 			break;
134 
135 		case 'R':
136 			wantrestart = 1;
137 			break;
138 		case 'r':
139 			inoopt++;
140 			break;
141 
142 		case 'S':
143 			surrender = 1;
144 			break;
145 
146 		case 'y':
147 			yflag++;
148 			nflag = 0;
149 			break;
150 
151 		case 'Z':
152 			Zflag++;
153 			break;
154 
155 		case 'z':
156 			zflag++;
157 			break;
158 
159 		default:
160 			usage();
161 		}
162 	}
163 	argc -= optind;
164 	argv += optind;
165 
166 	if (!argc)
167 		usage();
168 
169 	if (bkgrdflag && cvtlevel > 0) {
170 		pfatal("CANNOT CONVERT A SNAPSHOT\n");
171 		exit(EEXIT);
172 	}
173 
174 	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
175 		(void)signal(SIGINT, catch);
176 	if (ckclean)
177 		(void)signal(SIGQUIT, catchquit);
178 	signal(SIGINFO, infohandler);
179 	if (bkgrdflag) {
180 		signal(SIGALRM, alarmhandler);
181 		itimerval.it_interval.tv_sec = 5;
182 		itimerval.it_interval.tv_usec = 0;
183 		itimerval.it_value.tv_sec = 5;
184 		itimerval.it_value.tv_usec = 0;
185 		setitimer(ITIMER_REAL, &itimerval, NULL);
186 	}
187 	/*
188 	 * Push up our allowed memory limit so we can cope
189 	 * with huge file systems.
190 	 */
191 	if (getrlimit(RLIMIT_DATA, &rlimit) == 0) {
192 		rlimit.rlim_cur = rlimit.rlim_max;
193 		(void)setrlimit(RLIMIT_DATA, &rlimit);
194 	}
195 	while (argc > 0) {
196 		if ((fsret = checkfilesys(*argv)) == ERESTART)
197 			continue;
198 		ret |= fsret;
199 		argc--;
200 		argv++;
201 	}
202 
203 	if (returntosingle)
204 		ret = 2;
205 	exit(ret);
206 }
207 
208 static intmax_t
209 argtoimax(int flag, const char *req, const char *str, int base)
210 {
211 	char *cp;
212 	intmax_t ret;
213 
214 	ret = strtoimax(str, &cp, base);
215 	if (cp == str || *cp)
216 		errx(EEXIT, "-%c flag requires a %s", flag, req);
217 	return (ret);
218 }
219 
220 /*
221  * Check the specified file system.
222  */
223 /* ARGSUSED */
224 static int
225 checkfilesys(char *filesys)
226 {
227 	ufs2_daddr_t n_ffree, n_bfree;
228 	struct dups *dp;
229 	struct statfs *mntp;
230 	intmax_t blks, files;
231 	size_t size;
232 	int sbreadfailed, ofsmodified;
233 
234 	fsutilinit();
235 	fsckinit();
236 
237 	cdevname = filesys;
238 	if (debug && ckclean)
239 		pwarn("starting\n");
240 	/*
241 	 * Make best effort to get the disk name. Check first to see
242 	 * if it is listed among the mounted file systems. Failing that
243 	 * check to see if it is listed in /etc/fstab.
244 	 */
245 	mntp = getmntpoint(filesys);
246 	if (mntp != NULL)
247 		filesys = mntp->f_mntfromname;
248 	else
249 		filesys = blockcheck(filesys);
250 	/*
251 	 * If -F flag specified, check to see whether a background check
252 	 * is possible and needed. If possible and needed, exit with
253 	 * status zero. Otherwise exit with status non-zero. A non-zero
254 	 * exit status will cause a foreground check to be run.
255 	 */
256 	sblock_init();
257 	sbreadfailed = 0;
258 	if (openfilesys(filesys) == 0 || readsb() == 0)
259 		sbreadfailed = 1;
260 	if (bkgrdcheck) {
261 		if (sbreadfailed)
262 			exit(3);	/* Cannot read superblock */
263 		if ((sblock.fs_flags & FS_NEEDSFSCK) == FS_NEEDSFSCK)
264 			exit(4);	/* Earlier background failed */
265 		if ((sblock.fs_flags & FS_SUJ) == FS_SUJ) {
266 			maxino = sblock.fs_ncg * sblock.fs_ipg;
267 			maxfsblock = sblock.fs_size;
268 			bufinit();
269 			preen = 1;
270 			if (suj_check(filesys) == 0)
271 				exit(4); /* Journal good, run it now */
272 		}
273 		if ((sblock.fs_flags & FS_DOSOFTDEP) == 0)
274 			exit(5);	/* Not running soft updates */
275 		size = MIBSIZE;
276 		if (sysctlnametomib("vfs.ffs.adjrefcnt", adjrefcnt, &size) < 0)
277 			exit(6);	/* Lacks kernel support */
278 		if ((mntp == NULL && sblock.fs_clean == 1) ||
279 		    (mntp != NULL && (sblock.fs_flags & FS_UNCLEAN) == 0))
280 			exit(7);	/* Filesystem clean, report it now */
281 		exit(0);
282 	}
283 	if (ckclean && skipclean) {
284 		/*
285 		 * If file system is gjournaled, check it here.
286 		 */
287 		if (sbreadfailed)
288 			exit(3);	/* Cannot read superblock */
289 		if (bkgrdflag == 0 &&
290 		    (nflag || (fswritefd = open(filesys, O_WRONLY)) < 0)) {
291 			fswritefd = -1;
292 			if (preen)
293 				pfatal("NO WRITE ACCESS");
294 			printf(" (NO WRITE)");
295 		}
296 		if ((sblock.fs_flags & FS_GJOURNAL) != 0) {
297 			if (sblock.fs_clean == 1) {
298 				pwarn("FILE SYSTEM CLEAN; SKIPPING CHECKS\n");
299 				exit(0);
300 			}
301 			if ((sblock.fs_flags &
302 			    (FS_UNCLEAN | FS_NEEDSFSCK)) == 0) {
303 				bufinit();
304 				gjournal_check(filesys);
305 				if (chkdoreload(mntp, pwarn) == 0)
306 					exit(0);
307 				exit(4);
308 			} else {
309 				pfatal("FULL FSCK NEEDED, CANNOT RUN FAST "
310 				    "FSCK\n");
311 			}
312 		}
313 		close(fswritefd);
314 		fswritefd = -1;
315 	}
316 	if (bkgrdflag) {
317 		switch (setup_bkgrdchk(mntp, sbreadfailed, &filesys)) {
318 		case -1: /* filesystem clean */
319 			goto clean;
320 		case 0: /* cannot do background, give up */
321 			exit(EEXIT);
322 		case 1: /* doing background check, preen rules apply */
323 			preen = 1;
324 			break;
325 		}
326 	}
327 
328 	switch (setup(filesys)) {
329 	case 0:
330 		if (preen)
331 			pfatal("CAN'T CHECK FILE SYSTEM.");
332 		return (EEXIT);
333 	case -1:
334 	clean:
335 		pwarn("clean, %ld free ", (long)(sblock.fs_cstotal.cs_nffree +
336 		    sblock.fs_frag * sblock.fs_cstotal.cs_nbfree));
337 		printf("(%jd frags, %jd blocks, %.1f%% fragmentation)\n",
338 		    (intmax_t)sblock.fs_cstotal.cs_nffree,
339 		    (intmax_t)sblock.fs_cstotal.cs_nbfree,
340 		    sblock.fs_cstotal.cs_nffree * 100.0 / sblock.fs_dsize);
341 		return (0);
342 	}
343 	/*
344 	 * Determine if we can and should do journal recovery.
345 	 */
346 	if (bkgrdflag == 0 && (sblock.fs_flags & FS_SUJ) == FS_SUJ) {
347 		if ((sblock.fs_flags & FS_NEEDSFSCK) != FS_NEEDSFSCK &&
348 		    skipclean) {
349 			sujrecovery = 1;
350 			if (suj_check(filesys) == 0) {
351 				pwarn("\n**** FILE SYSTEM MARKED CLEAN ****\n");
352 				if (chkdoreload(mntp, pwarn) == 0)
353 					exit(0);
354 				exit(4);
355 			}
356 			sujrecovery = 0;
357 			pwarn("Skipping journal, "
358 			    "falling through to full fsck\n");
359 		}
360 		if (fswritefd != -1) {
361 			/*
362 			 * Write the superblock so we don't try to recover the
363 			 * journal on another pass. If this is the only change
364 			 * to the filesystem, we do not want it to be called
365 			 * out as modified.
366 			 */
367 			sblock.fs_mtime = time(NULL);
368 			sbdirty();
369 			ofsmodified = fsmodified;
370 			flush(fswritefd, &sblk);
371 			fsmodified = ofsmodified;
372 		}
373 	}
374 	/*
375 	 * If the filesystem was run on an old kernel that did not
376 	 * support check hashes, clear the check-hash flags so that
377 	 * we do not try to verify them.
378 	 */
379 	if ((sblock.fs_flags & FS_METACKHASH) == 0)
380 		sblock.fs_metackhash = 0;
381 	/*
382 	 * If we are running on a kernel that can provide check hashes
383 	 * that are not yet enabled for the filesystem and we are
384 	 * running manually without the -y flag, offer to add any
385 	 * supported check hashes that are not already enabled.
386 	 */
387 	ckhashadd = 0;
388 	if (preen == 0 && yflag == 0 && sblock.fs_magic != FS_UFS1_MAGIC &&
389 	    fswritefd != -1 && getosreldate() >= P_OSREL_CK_CYLGRP) {
390 		if ((sblock.fs_metackhash & CK_CYLGRP) == 0 &&
391 		    reply("ADD CYLINDER GROUP CHECK-HASH PROTECTION") != 0) {
392 			ckhashadd |= CK_CYLGRP;
393 			sblock.fs_metackhash |= CK_CYLGRP;
394 		}
395 		if ((sblock.fs_metackhash & CK_SUPERBLOCK) == 0 &&
396 		    getosreldate() >= P_OSREL_CK_SUPERBLOCK &&
397 		    reply("ADD SUPERBLOCK CHECK-HASH PROTECTION") != 0) {
398 			ckhashadd |= CK_SUPERBLOCK;
399 			sblock.fs_metackhash |= CK_SUPERBLOCK;
400 		}
401 		if ((sblock.fs_metackhash & CK_INODE) == 0 &&
402 		    getosreldate() >= P_OSREL_CK_INODE &&
403 		    reply("ADD INODE CHECK-HASH PROTECTION") != 0) {
404 			ckhashadd |= CK_INODE;
405 			sblock.fs_metackhash |= CK_INODE;
406 		}
407 #ifdef notyet
408 		if ((sblock.fs_metackhash & CK_INDIR) == 0 &&
409 		    getosreldate() >= P_OSREL_CK_INDIR &&
410 		    reply("ADD INDIRECT BLOCK CHECK-HASH PROTECTION") != 0) {
411 			ckhashadd |= CK_INDIR;
412 			sblock.fs_metackhash |= CK_INDIR;
413 		}
414 		if ((sblock.fs_metackhash & CK_DIR) == 0 &&
415 		    getosreldate() >= P_OSREL_CK_DIR &&
416 		    reply("ADD DIRECTORY CHECK-HASH PROTECTION") != 0) {
417 			ckhashadd |= CK_DIR;
418 			sblock.fs_metackhash |= CK_DIR;
419 		}
420 #endif /* notyet */
421 		if (ckhashadd != 0) {
422 			sblock.fs_flags |= FS_METACKHASH;
423 			sbdirty();
424 		}
425 	}
426 	/*
427 	 * Cleared if any questions answered no. Used to decide if
428 	 * the superblock should be marked clean.
429 	 */
430 	resolved = 1;
431 	/*
432 	 * 1: scan inodes tallying blocks used
433 	 */
434 	if (preen == 0 || debug) {
435 		printf("** Last Mounted on %s\n", sblock.fs_fsmnt);
436 		if (mntp != NULL && mntp->f_flags & MNT_ROOTFS)
437 			printf("** Root file system\n");
438 		printf("** Phase 1 - Check Blocks and Sizes\n");
439 	}
440 	clock_gettime(CLOCK_REALTIME_PRECISE, &startprog);
441 	pass1();
442 	IOstats("Pass1");
443 
444 	/*
445 	 * 1b: locate first references to duplicates, if any
446 	 */
447 	if (duplist) {
448 		if (preen || usedsoftdep)
449 			pfatal("INTERNAL ERROR: DUPS WITH %s%s%s",
450 			    preen ? "-p" : "",
451 			    (preen && usedsoftdep) ? " AND " : "",
452 			    usedsoftdep ? "SOFTUPDATES" : "");
453 		if (preen == 0 || debug)
454 			printf("** Phase 1b - Rescan For More DUPS\n");
455 		pass1b();
456 		IOstats("Pass1b");
457 	}
458 
459 	/*
460 	 * 2: traverse directories from root to mark all connected directories
461 	 */
462 	if (preen == 0 || debug)
463 		printf("** Phase 2 - Check Pathnames\n");
464 	pass2();
465 	IOstats("Pass2");
466 
467 	/*
468 	 * 3: scan inodes looking for disconnected directories
469 	 */
470 	if (preen == 0 || debug)
471 		printf("** Phase 3 - Check Connectivity\n");
472 	pass3();
473 	IOstats("Pass3");
474 
475 	/*
476 	 * 4: scan inodes looking for disconnected files; check reference counts
477 	 */
478 	if (preen == 0 || debug)
479 		printf("** Phase 4 - Check Reference Counts\n");
480 	pass4();
481 	IOstats("Pass4");
482 
483 	/*
484 	 * 5: check and repair resource counts in cylinder groups
485 	 */
486 	if (preen == 0 || debug)
487 		printf("** Phase 5 - Check Cyl groups\n");
488 	snapflush(std_checkblkavail);
489 	if (cgheader_corrupt) {
490 		printf("PHASE 5 SKIPPED DUE TO CORRUPT CYLINDER GROUP "
491 		    "HEADER(S)\n\n");
492 	} else {
493 		pass5();
494 		IOstats("Pass5");
495 	}
496 
497 	/*
498 	 * print out summary statistics
499 	 */
500 	n_ffree = sblock.fs_cstotal.cs_nffree;
501 	n_bfree = sblock.fs_cstotal.cs_nbfree;
502 	files = maxino - UFS_ROOTINO - sblock.fs_cstotal.cs_nifree - n_files;
503 	blks = n_blks +
504 	    sblock.fs_ncg * (cgdmin(&sblock, 0) - cgsblock(&sblock, 0));
505 	blks += cgsblock(&sblock, 0) - cgbase(&sblock, 0);
506 	blks += howmany(sblock.fs_cssize, sblock.fs_fsize);
507 	blks = maxfsblock - (n_ffree + sblock.fs_frag * n_bfree) - blks;
508 	if (bkgrdflag && (files > 0 || blks > 0)) {
509 		countdirs = sblock.fs_cstotal.cs_ndir - countdirs;
510 		pwarn("Reclaimed: %ld directories, %jd files, %jd fragments\n",
511 		    countdirs, files - countdirs, blks);
512 	}
513 	pwarn("%ld files, %jd used, %ju free ",
514 	    (long)n_files, (intmax_t)n_blks,
515 	    (uintmax_t)n_ffree + sblock.fs_frag * n_bfree);
516 	printf("(%ju frags, %ju blocks, %.1f%% fragmentation)\n",
517 	    (uintmax_t)n_ffree, (uintmax_t)n_bfree,
518 	    n_ffree * 100.0 / sblock.fs_dsize);
519 	if (debug) {
520 		if (files < 0)
521 			printf("%jd inodes missing\n", -files);
522 		if (blks < 0)
523 			printf("%jd blocks missing\n", -blks);
524 		if (duplist != NULL) {
525 			printf("The following duplicate blocks remain:");
526 			for (dp = duplist; dp; dp = dp->next)
527 				printf(" %jd,", (intmax_t)dp->dup);
528 			printf("\n");
529 		}
530 	}
531 	duplist = (struct dups *)0;
532 	muldup = (struct dups *)0;
533 	inocleanup();
534 	if (fsmodified) {
535 		sblock.fs_time = time(NULL);
536 		sbdirty();
537 	}
538 	if (cvtlevel && (sblk.b_flags & B_DIRTY) != 0) {
539 		/*
540 		 * Write out the duplicate super blocks
541 		 */
542 		if (sbput(fswritefd, &sblock, sblock.fs_ncg) == 0)
543 			fsmodified = 1;
544 	}
545 	if (rerun)
546 		resolved = 0;
547 
548 	/*
549 	 * Check to see if the file system is mounted read-write.
550 	 */
551 	if (bkgrdflag == 0 && mntp != NULL && (mntp->f_flags & MNT_RDONLY) == 0)
552 		resolved = 0;
553 	ckfini(resolved);
554 
555 	if (fsmodified && !preen)
556 		printf("\n***** FILE SYSTEM WAS MODIFIED *****\n");
557 	if (rerun) {
558 		if (wantrestart && (restarts++ < 10) &&
559 		    (preen || reply("RESTART")))
560 			return (ERESTART);
561 		printf("\n***** PLEASE RERUN FSCK *****\n");
562 	}
563 	if (chkdoreload(mntp, pwarn) != 0) {
564 		if (!fsmodified)
565 			return (0);
566 		if (!preen)
567 			printf("\n***** REBOOT NOW *****\n");
568 		sync();
569 		return (4);
570 	}
571 	return (rerun ? ERERUN : 0);
572 }
573 
574 /*
575  * If we are to do a background check:
576  *	Get the mount point information of the file system
577  *	If already clean, return -1
578  *	Check that kernel supports background fsck
579  *	Find or create the snapshot directory
580  *	Create the snapshot file
581  *	Open snapshot
582  *	If anything fails print reason and return 0 which exits
583  */
584 static int
585 setup_bkgrdchk(struct statfs *mntp, int sbreadfailed, char **filesys)
586 {
587 	struct stat snapdir;
588 	struct group *grp;
589 	struct iovec *iov;
590 	char errmsg[255];
591 	int iovlen;
592 	size_t size;
593 
594 	/* Get the mount point information of the file system */
595 	if (mntp == NULL) {
596 		pwarn("NOT MOUNTED, CANNOT RUN IN BACKGROUND\n");
597 		return (0);
598 	}
599 	if ((mntp->f_flags & MNT_RDONLY) != 0) {
600 		pwarn("MOUNTED READ-ONLY, CANNOT RUN IN BACKGROUND\n");
601 		return (0);
602 	}
603 	if ((mntp->f_flags & MNT_SOFTDEP) == 0) {
604 		pwarn("NOT USING SOFT UPDATES, CANNOT RUN IN BACKGROUND\n");
605 		return (0);
606 	}
607 	if (sbreadfailed) {
608 		pwarn("SUPERBLOCK READ FAILED, CANNOT RUN IN BACKGROUND\n");
609 		return (0);
610 	}
611 	if ((sblock.fs_flags & FS_NEEDSFSCK) != 0) {
612 		pwarn("FULL FSCK NEEDED, CANNOT RUN IN BACKGROUND\n");
613 		return (0);
614 	}
615 	if (skipclean && ckclean &&
616 	   (sblock.fs_flags & (FS_UNCLEAN|FS_NEEDSFSCK)) == 0) {
617 		/*
618 		 * file system is clean;
619 		 * skip snapshot and report it clean
620 		 */
621 		pwarn("FILE SYSTEM CLEAN; SKIPPING CHECKS\n");
622 		return (-1);
623 	}
624 	/* Check that kernel supports background fsck */
625 	size = MIBSIZE;
626 	if (sysctlnametomib("vfs.ffs.adjrefcnt", adjrefcnt, &size) < 0||
627 	    sysctlnametomib("vfs.ffs.adjblkcnt", adjblkcnt, &size) < 0||
628 	    sysctlnametomib("vfs.ffs.setsize", setsize, &size) < 0 ||
629 	    sysctlnametomib("vfs.ffs.freefiles", freefiles, &size) < 0||
630 	    sysctlnametomib("vfs.ffs.freedirs", freedirs, &size) < 0 ||
631 	    sysctlnametomib("vfs.ffs.freeblks", freeblks, &size) < 0) {
632 		pwarn("KERNEL LACKS BACKGROUND FSCK SUPPORT\n");
633 		return (0);
634 	}
635 	/*
636 	 * When kernel lacks runtime bgfsck superblock summary
637 	 * adjustment functionality, it does not mean we can not
638 	 * continue, as old kernels will recompute the summary at
639 	 * mount time. However, it will be an unexpected softupdates
640 	 * inconsistency if it turns out that the summary is still
641 	 * incorrect. Set a flag so subsequent operation can know this.
642 	 */
643 	bkgrdsumadj = 1;
644 	if (sysctlnametomib("vfs.ffs.adjndir", adjndir, &size) < 0 ||
645 	   sysctlnametomib("vfs.ffs.adjnbfree", adjnbfree, &size) < 0 ||
646 	   sysctlnametomib("vfs.ffs.adjnifree", adjnifree, &size) < 0 ||
647 	   sysctlnametomib("vfs.ffs.adjnffree", adjnffree, &size) < 0 ||
648 	   sysctlnametomib("vfs.ffs.adjnumclusters", adjnumclusters,
649 	   &size) < 0) {
650 		bkgrdsumadj = 0;
651 		pwarn("KERNEL LACKS RUNTIME SUPERBLOCK SUMMARY ADJUSTMENT "
652 		    "SUPPORT\n");
653 	}
654 	/* Find or create the snapshot directory */
655 	snprintf(snapname, sizeof snapname, "%s/.snap", mntp->f_mntonname);
656 	if (stat(snapname, &snapdir) < 0) {
657 		if (errno != ENOENT) {
658 			pwarn("CANNOT FIND SNAPSHOT DIRECTORY %s: %s, CANNOT "
659 			    "RUN IN BACKGROUND\n", snapname, strerror(errno));
660 			return (0);
661 		}
662 		if ((grp = getgrnam("operator")) == NULL ||
663 			   mkdir(snapname, 0770) < 0 ||
664 			   chown(snapname, -1, grp->gr_gid) < 0 ||
665 			   chmod(snapname, 0770) < 0) {
666 			pwarn("CANNOT CREATE SNAPSHOT DIRECTORY %s: %s, "
667 			    "CANNOT RUN IN BACKGROUND\n", snapname,
668 			    strerror(errno));
669 			return (0);
670 		}
671 	} else if (!S_ISDIR(snapdir.st_mode)) {
672 		pwarn("%s IS NOT A DIRECTORY, CANNOT RUN IN BACKGROUND\n",
673 		    snapname);
674 		return (0);
675 	}
676 	/* Create the snapshot file */
677 	iov = NULL;
678 	iovlen = 0;
679 	errmsg[0] = '\0';
680 	snprintf(snapname, sizeof snapname, "%s/.snap/fsck_snapshot",
681 	    mntp->f_mntonname);
682 	build_iovec(&iov, &iovlen, "fstype", "ffs", 4);
683 	build_iovec(&iov, &iovlen, "from", snapname, (size_t)-1);
684 	build_iovec(&iov, &iovlen, "fspath", mntp->f_mntonname, (size_t)-1);
685 	build_iovec(&iov, &iovlen, "errmsg", errmsg, sizeof(errmsg));
686 	build_iovec(&iov, &iovlen, "update", NULL, 0);
687 	build_iovec(&iov, &iovlen, "snapshot", NULL, 0);
688 	/* Create snapshot, removing old snapshot if it exists */
689 	while (nmount(iov, iovlen, mntp->f_flags) < 0) {
690 		if (errno == EEXIST && unlink(snapname) == 0)
691 			continue;
692 		pwarn("CANNOT CREATE SNAPSHOT %s: %s %s\n", snapname,
693 		    strerror(errno), errmsg);
694 		return (0);
695 	}
696 	/* Open snapshot */
697 	if (openfilesys(snapname) == 0) {
698 		unlink(snapname);
699 		pwarn("CANNOT OPEN SNAPSHOT %s: %s, CANNOT RUN IN "
700 		    "BACKGROUND\n", snapname, strerror(errno));
701 		return (0);
702 	}
703 	/* Immediately unlink snapshot so that it will be deleted when closed */
704 	unlink(snapname);
705 	free(sblock.fs_csp);
706 	free(sblock.fs_si);
707 	if (readsb() == 0) {
708 		pwarn("CANNOT READ SNAPSHOT SUPERBLOCK\n");
709 		return (0);
710 	}
711 	*filesys = snapname;
712 	cmd.version = FFS_CMD_VERSION;
713 	cmd.handle = fsreadfd;
714 	return (1);
715 }
716 
717 static void
718 usage(void)
719 {
720 	(void) fprintf(stderr,
721 "usage: %s [-BCdEFfnpRrSyZ] [-b block] [-c level] [-m mode] filesystem ...\n",
722 	    getprogname());
723 	exit(1);
724 }
725 
726 void
727 infohandler(int sig __unused)
728 {
729 	got_siginfo = 1;
730 }
731 
732 void
733 alarmhandler(int sig __unused)
734 {
735 	got_sigalarm = 1;
736 }
737