xref: /freebsd/sys/kern/vfs_mountroot.c (revision f5f7c05209ca2c3748fd8b27c5e80ffad49120eb)
1 /*-
2  * Copyright (c) 2010 Marcel Moolenaar
3  * Copyright (c) 1999-2004 Poul-Henning Kamp
4  * Copyright (c) 1999 Michael Smith
5  * Copyright (c) 1989, 1993
6  *      The Regents of the University of California.  All rights reserved.
7  * (c) UNIX System Laboratories, Inc.
8  * All or some portions of this file are derived from material licensed
9  * to the University of California by American Telephone and Telegraph
10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
11  * the permission of UNIX System Laboratories, Inc.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 4. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  */
37 
38 #include "opt_rootdevname.h"
39 
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
42 
43 #include <sys/param.h>
44 #include <sys/conf.h>
45 #include <sys/cons.h>
46 #include <sys/fcntl.h>
47 #include <sys/jail.h>
48 #include <sys/kernel.h>
49 #include <sys/malloc.h>
50 #include <sys/mdioctl.h>
51 #include <sys/mount.h>
52 #include <sys/mutex.h>
53 #include <sys/namei.h>
54 #include <sys/priv.h>
55 #include <sys/proc.h>
56 #include <sys/filedesc.h>
57 #include <sys/reboot.h>
58 #include <sys/sbuf.h>
59 #include <sys/stat.h>
60 #include <sys/syscallsubr.h>
61 #include <sys/sysproto.h>
62 #include <sys/sx.h>
63 #include <sys/sysctl.h>
64 #include <sys/sysent.h>
65 #include <sys/systm.h>
66 #include <sys/vnode.h>
67 
68 #include <geom/geom.h>
69 
70 /*
71  * The root filesystem is detailed in the kernel environment variable
72  * vfs.root.mountfrom, which is expected to be in the general format
73  *
74  * <vfsname>:[<path>][	<vfsname>:[<path>] ...]
75  * vfsname   := the name of a VFS known to the kernel and capable
76  *              of being mounted as root
77  * path      := disk device name or other data used by the filesystem
78  *              to locate its physical store
79  *
80  * If the environment variable vfs.root.mountfrom is a space separated list,
81  * each list element is tried in turn and the root filesystem will be mounted
82  * from the first one that suceeds.
83  *
84  * The environment variable vfs.root.mountfrom.options is a comma delimited
85  * set of string mount options.  These mount options must be parseable
86  * by nmount() in the kernel.
87  */
88 
89 static int parse_mount(char **);
90 static struct mntarg *parse_mountroot_options(struct mntarg *, const char *);
91 
92 /*
93  * The vnode of the system's root (/ in the filesystem, without chroot
94  * active.)
95  */
96 struct vnode *rootvnode;
97 
98 char *rootdevnames[2] = {NULL, NULL};
99 
100 struct root_hold_token {
101 	const char			*who;
102 	LIST_ENTRY(root_hold_token)	list;
103 };
104 
105 static LIST_HEAD(, root_hold_token)	root_holds =
106     LIST_HEAD_INITIALIZER(root_holds);
107 
108 enum action {
109 	A_CONTINUE,
110 	A_PANIC,
111 	A_REBOOT,
112 	A_RETRY
113 };
114 
115 static enum action root_mount_onfail = A_CONTINUE;
116 
117 static int root_mount_mddev;
118 static int root_mount_complete;
119 
120 /* By default wait up to 3 seconds for devices to appear. */
121 static int root_mount_timeout = 3;
122 
123 struct root_hold_token *
124 root_mount_hold(const char *identifier)
125 {
126 	struct root_hold_token *h;
127 
128 	if (root_mounted())
129 		return (NULL);
130 
131 	h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
132 	h->who = identifier;
133 	mtx_lock(&mountlist_mtx);
134 	LIST_INSERT_HEAD(&root_holds, h, list);
135 	mtx_unlock(&mountlist_mtx);
136 	return (h);
137 }
138 
139 void
140 root_mount_rel(struct root_hold_token *h)
141 {
142 
143 	if (h == NULL)
144 		return;
145 	mtx_lock(&mountlist_mtx);
146 	LIST_REMOVE(h, list);
147 	wakeup(&root_holds);
148 	mtx_unlock(&mountlist_mtx);
149 	free(h, M_DEVBUF);
150 }
151 
152 int
153 root_mounted(void)
154 {
155 
156 	/* No mutex is acquired here because int stores are atomic. */
157 	return (root_mount_complete);
158 }
159 
160 void
161 root_mount_wait(void)
162 {
163 
164 	/*
165 	 * Panic on an obvious deadlock - the function can't be called from
166 	 * a thread which is doing the whole SYSINIT stuff.
167 	 */
168 	KASSERT(curthread->td_proc->p_pid != 0,
169 	    ("root_mount_wait: cannot be called from the swapper thread"));
170 	mtx_lock(&mountlist_mtx);
171 	while (!root_mount_complete) {
172 		msleep(&root_mount_complete, &mountlist_mtx, PZERO, "rootwait",
173 		    hz);
174 	}
175 	mtx_unlock(&mountlist_mtx);
176 }
177 
178 static void
179 set_rootvnode(void)
180 {
181 	struct proc *p;
182 
183 	if (VFS_ROOT(TAILQ_FIRST(&mountlist), LK_EXCLUSIVE, &rootvnode))
184 		panic("Cannot find root vnode");
185 
186 	VOP_UNLOCK(rootvnode, 0);
187 
188 	p = curthread->td_proc;
189 	FILEDESC_XLOCK(p->p_fd);
190 
191 	if (p->p_fd->fd_cdir != NULL)
192 		vrele(p->p_fd->fd_cdir);
193 	p->p_fd->fd_cdir = rootvnode;
194 	VREF(rootvnode);
195 
196 	if (p->p_fd->fd_rdir != NULL)
197 		vrele(p->p_fd->fd_rdir);
198 	p->p_fd->fd_rdir = rootvnode;
199 	VREF(rootvnode);
200 
201 	FILEDESC_XUNLOCK(p->p_fd);
202 
203 	EVENTHANDLER_INVOKE(mountroot);
204 }
205 
206 static int
207 vfs_mountroot_devfs(struct thread *td, struct mount **mpp)
208 {
209 	struct vfsoptlist *opts;
210 	struct vfsconf *vfsp;
211 	struct mount *mp;
212 	int error;
213 
214 	*mpp = NULL;
215 
216 	vfsp = vfs_byname("devfs");
217 	KASSERT(vfsp != NULL, ("Could not find devfs by name"));
218 	if (vfsp == NULL)
219 		return (ENOENT);
220 
221 	mp = vfs_mount_alloc(NULLVP, vfsp, "/dev", td->td_ucred);
222 
223 	error = VFS_MOUNT(mp);
224 	KASSERT(error == 0, ("VFS_MOUNT(devfs) failed %d", error));
225 	if (error)
226 		return (error);
227 
228 	opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
229 	TAILQ_INIT(opts);
230 	mp->mnt_opt = opts;
231 
232 	mtx_lock(&mountlist_mtx);
233 	TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
234 	mtx_unlock(&mountlist_mtx);
235 
236 	*mpp = mp;
237 	set_rootvnode();
238 
239 	error = kern_symlink(td, "/", "dev", UIO_SYSSPACE);
240 	if (error)
241 		printf("kern_symlink /dev -> / returns %d\n", error);
242 
243 	return (error);
244 }
245 
246 static int
247 vfs_mountroot_shuffle(struct thread *td, struct mount *mpdevfs)
248 {
249 	struct nameidata nd;
250 	struct mount *mporoot, *mpnroot;
251 	struct vnode *vp, *vporoot, *vpdevfs;
252 	char *fspath;
253 	int error;
254 
255 	mpnroot = TAILQ_NEXT(mpdevfs, mnt_list);
256 
257 	/* Shuffle the mountlist. */
258 	mtx_lock(&mountlist_mtx);
259 	mporoot = TAILQ_FIRST(&mountlist);
260 	TAILQ_REMOVE(&mountlist, mpdevfs, mnt_list);
261 	if (mporoot != mpdevfs) {
262 		TAILQ_REMOVE(&mountlist, mpnroot, mnt_list);
263 		TAILQ_INSERT_HEAD(&mountlist, mpnroot, mnt_list);
264 	}
265 	TAILQ_INSERT_TAIL(&mountlist, mpdevfs, mnt_list);
266 	mtx_unlock(&mountlist_mtx);
267 
268 	cache_purgevfs(mporoot);
269 	if (mporoot != mpdevfs)
270 		cache_purgevfs(mpdevfs);
271 
272 	VFS_ROOT(mporoot, LK_EXCLUSIVE, &vporoot);
273 
274 	VI_LOCK(vporoot);
275 	vporoot->v_iflag &= ~VI_MOUNT;
276 	VI_UNLOCK(vporoot);
277 	vporoot->v_mountedhere = NULL;
278 	mporoot->mnt_flag &= ~MNT_ROOTFS;
279 	mporoot->mnt_vnodecovered = NULL;
280 	vput(vporoot);
281 
282 	/* Set up the new rootvnode, and purge the cache */
283 	mpnroot->mnt_vnodecovered = NULL;
284 	set_rootvnode();
285 	cache_purgevfs(rootvnode->v_mount);
286 
287 	if (mporoot != mpdevfs) {
288 		/* Remount old root under /.mount or /mnt */
289 		fspath = "/.mount";
290 		NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
291 		    fspath, td);
292 		error = namei(&nd);
293 		if (error) {
294 			NDFREE(&nd, NDF_ONLY_PNBUF);
295 			fspath = "/mnt";
296 			NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
297 			    fspath, td);
298 			error = namei(&nd);
299 		}
300 		if (!error) {
301 			vp = nd.ni_vp;
302 			error = (vp->v_type == VDIR) ? 0 : ENOTDIR;
303 			if (!error)
304 				error = vinvalbuf(vp, V_SAVE, 0, 0);
305 			if (!error) {
306 				cache_purge(vp);
307 				mporoot->mnt_vnodecovered = vp;
308 				vp->v_mountedhere = mporoot;
309 				strlcpy(mporoot->mnt_stat.f_mntonname,
310 				    fspath, MNAMELEN);
311 				VOP_UNLOCK(vp, 0);
312 			} else
313 				vput(vp);
314 		}
315 		NDFREE(&nd, NDF_ONLY_PNBUF);
316 
317 		if (error && bootverbose)
318 			printf("mountroot: unable to remount previous root "
319 			    "under /.mount or /mnt (error %d).\n", error);
320 	}
321 
322 	/* Remount devfs under /dev */
323 	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, "/dev", td);
324 	error = namei(&nd);
325 	if (!error) {
326 		vp = nd.ni_vp;
327 		error = (vp->v_type == VDIR) ? 0 : ENOTDIR;
328 		if (!error)
329 			error = vinvalbuf(vp, V_SAVE, 0, 0);
330 		if (!error) {
331 			vpdevfs = mpdevfs->mnt_vnodecovered;
332 			if (vpdevfs != NULL) {
333 				cache_purge(vpdevfs);
334 				vpdevfs->v_mountedhere = NULL;
335 				vrele(vpdevfs);
336 			}
337 			mpdevfs->mnt_vnodecovered = vp;
338 			vp->v_mountedhere = mpdevfs;
339 			VOP_UNLOCK(vp, 0);
340 		} else
341 			vput(vp);
342 	}
343 	if (error && bootverbose)
344 		printf("mountroot: unable to remount devfs under /dev "
345 		    "(error %d).\n", error);
346 	NDFREE(&nd, NDF_ONLY_PNBUF);
347 
348 	if (mporoot == mpdevfs) {
349 		vfs_unbusy(mpdevfs);
350 		/* Unlink the no longer needed /dev/dev -> / symlink */
351 		error = kern_unlink(td, "/dev/dev", UIO_SYSSPACE);
352 		if (error && bootverbose)
353 			printf("mountroot: unable to unlink /dev/dev "
354 			    "(error %d)\n", error);
355 	}
356 
357 	return (0);
358 }
359 
360 /*
361  * Configuration parser.
362  */
363 
364 /* Parser character classes. */
365 #define	CC_WHITESPACE		-1
366 #define	CC_NONWHITESPACE	-2
367 
368 /* Parse errors. */
369 #define	PE_EOF			-1
370 #define	PE_EOL			-2
371 
372 static __inline int
373 parse_peek(char **conf)
374 {
375 
376 	return (**conf);
377 }
378 
379 static __inline void
380 parse_poke(char **conf, int c)
381 {
382 
383 	**conf = c;
384 }
385 
386 static __inline void
387 parse_advance(char **conf)
388 {
389 
390 	(*conf)++;
391 }
392 
393 static __inline int
394 parse_isspace(int c)
395 {
396 
397 	return ((c == ' ' || c == '\t' || c == '\n') ? 1 : 0);
398 }
399 
400 static int
401 parse_skipto(char **conf, int mc)
402 {
403 	int c, match;
404 
405 	while (1) {
406 		c = parse_peek(conf);
407 		if (c == 0)
408 			return (PE_EOF);
409 		switch (mc) {
410 		case CC_WHITESPACE:
411 			match = (c == ' ' || c == '\t' || c == '\n') ? 1 : 0;
412 			break;
413 		case CC_NONWHITESPACE:
414 			if (c == '\n')
415 				return (PE_EOL);
416 			match = (c != ' ' && c != '\t') ? 1 : 0;
417 			break;
418 		default:
419 			match = (c == mc) ? 1 : 0;
420 			break;
421 		}
422 		if (match)
423 			break;
424 		parse_advance(conf);
425 	}
426 	return (0);
427 }
428 
429 static int
430 parse_token(char **conf, char **tok)
431 {
432 	char *p;
433 	size_t len;
434 	int error;
435 
436 	*tok = NULL;
437 	error = parse_skipto(conf, CC_NONWHITESPACE);
438 	if (error)
439 		return (error);
440 	p = *conf;
441 	error = parse_skipto(conf, CC_WHITESPACE);
442 	len = *conf - p;
443 	*tok = malloc(len + 1, M_TEMP, M_WAITOK | M_ZERO);
444 	bcopy(p, *tok, len);
445 	return (0);
446 }
447 
448 static void
449 parse_dir_ask_printenv(const char *var)
450 {
451 	char *val;
452 
453 	val = getenv(var);
454 	if (val != NULL) {
455 		printf("  %s=%s\n", var, val);
456 		freeenv(val);
457 	}
458 }
459 
460 static int
461 parse_dir_ask(char **conf)
462 {
463 	char name[80];
464 	char *mnt;
465 	int error;
466 
467 	printf("\nLoader variables:\n");
468 	parse_dir_ask_printenv("vfs.root.mountfrom");
469 	parse_dir_ask_printenv("vfs.root.mountfrom.options");
470 
471 	printf("\nManual root filesystem specification:\n");
472 	printf("  <fstype>:<device> [options]\n");
473 	printf("      Mount <device> using filesystem <fstype>\n");
474 	printf("      and with the specified (optional) option list.\n");
475 	printf("\n");
476 	printf("    eg. ufs:/dev/da0s1a\n");
477 	printf("        zfs:tank\n");
478 	printf("        cd9660:/dev/acd0 ro\n");
479 	printf("          (which is equivalent to: ");
480 	printf("mount -t cd9660 -o ro /dev/acd0 /)\n");
481 	printf("\n");
482 	printf("  ?               List valid disk boot devices\n");
483 	printf("  .               Yield 1 second (for background tasks)\n");
484 	printf("  <empty line>    Abort manual input\n");
485 
486 	do {
487 		error = EINVAL;
488 		printf("\nmountroot> ");
489 		cngets(name, sizeof(name), GETS_ECHO);
490 		if (name[0] == '\0')
491 			break;
492 		if (name[0] == '?' && name[1] == '\0') {
493 			printf("\nList of GEOM managed disk devices:\n  ");
494 			g_dev_print();
495 			continue;
496 		}
497 		if (name[0] == '.' && name[1] == '\0') {
498 			pause("rmask", hz);
499 			continue;
500 		}
501 		mnt = name;
502 		error = parse_mount(&mnt);
503 		if (error == -1)
504 			printf("Invalid file system specification.\n");
505 	} while (error != 0);
506 
507 	return (error);
508 }
509 
510 static int
511 parse_dir_md(char **conf)
512 {
513 	struct stat sb;
514 	struct thread *td;
515 	struct md_ioctl *mdio;
516 	char *path, *tok;
517 	int error, fd, len;
518 
519 	td = curthread;
520 
521 	error = parse_token(conf, &tok);
522 	if (error)
523 		return (error);
524 
525 	len = strlen(tok);
526 	mdio = malloc(sizeof(*mdio) + len + 1, M_TEMP, M_WAITOK | M_ZERO);
527 	path = (void *)(mdio + 1);
528 	bcopy(tok, path, len);
529 	free(tok, M_TEMP);
530 
531 	/* Get file status. */
532 	error = kern_stat(td, path, UIO_SYSSPACE, &sb);
533 	if (error)
534 		goto out;
535 
536 	/* Open /dev/mdctl so that we can attach/detach. */
537 	error = kern_open(td, "/dev/" MDCTL_NAME, UIO_SYSSPACE, O_RDWR, 0);
538 	if (error)
539 		goto out;
540 
541 	fd = td->td_retval[0];
542 	mdio->md_version = MDIOVERSION;
543 	mdio->md_type = MD_VNODE;
544 
545 	if (root_mount_mddev != -1) {
546 		mdio->md_unit = root_mount_mddev;
547 		DROP_GIANT();
548 		error = kern_ioctl(td, fd, MDIOCDETACH, (void *)mdio);
549 		PICKUP_GIANT();
550 		/* Ignore errors. We don't care. */
551 		root_mount_mddev = -1;
552 	}
553 
554 	mdio->md_file = (void *)(mdio + 1);
555 	mdio->md_options = MD_AUTOUNIT | MD_READONLY;
556 	mdio->md_mediasize = sb.st_size;
557 	mdio->md_unit = 0;
558 	DROP_GIANT();
559 	error = kern_ioctl(td, fd, MDIOCATTACH, (void *)mdio);
560 	PICKUP_GIANT();
561 	if (error)
562 		goto out;
563 
564 	if (mdio->md_unit > 9) {
565 		printf("rootmount: too many md units\n");
566 		mdio->md_file = NULL;
567 		mdio->md_options = 0;
568 		mdio->md_mediasize = 0;
569 		DROP_GIANT();
570 		error = kern_ioctl(td, fd, MDIOCDETACH, (void *)mdio);
571 		PICKUP_GIANT();
572 		/* Ignore errors. We don't care. */
573 		error = ERANGE;
574 		goto out;
575 	}
576 
577 	root_mount_mddev = mdio->md_unit;
578 	printf(MD_NAME "%u attached to %s\n", root_mount_mddev, mdio->md_file);
579 
580 	error = kern_close(td, fd);
581 
582  out:
583 	free(mdio, M_TEMP);
584 	return (error);
585 }
586 
587 static int
588 parse_dir_onfail(char **conf)
589 {
590 	char *action;
591 	int error;
592 
593 	error = parse_token(conf, &action);
594 	if (error)
595 		return (error);
596 
597 	if (!strcmp(action, "continue"))
598 		root_mount_onfail = A_CONTINUE;
599 	else if (!strcmp(action, "panic"))
600 		root_mount_onfail = A_PANIC;
601 	else if (!strcmp(action, "reboot"))
602 		root_mount_onfail = A_REBOOT;
603 	else if (!strcmp(action, "retry"))
604 		root_mount_onfail = A_RETRY;
605 	else {
606 		printf("rootmount: %s: unknown action\n", action);
607 		error = EINVAL;
608 	}
609 
610 	free(action, M_TEMP);
611 	return (0);
612 }
613 
614 static int
615 parse_dir_timeout(char **conf)
616 {
617 	char *tok, *endtok;
618 	long secs;
619 	int error;
620 
621 	error = parse_token(conf, &tok);
622 	if (error)
623 		return (error);
624 
625 	secs = strtol(tok, &endtok, 0);
626 	error = (secs < 0 || *endtok != '\0') ? EINVAL : 0;
627 	if (!error)
628 		root_mount_timeout = secs;
629 	free(tok, M_TEMP);
630 	return (error);
631 }
632 
633 static int
634 parse_directive(char **conf)
635 {
636 	char *dir;
637 	int error;
638 
639 	error = parse_token(conf, &dir);
640 	if (error)
641 		return (error);
642 
643 	if (strcmp(dir, ".ask") == 0)
644 		error = parse_dir_ask(conf);
645 	else if (strcmp(dir, ".md") == 0)
646 		error = parse_dir_md(conf);
647 	else if (strcmp(dir, ".onfail") == 0)
648 		error = parse_dir_onfail(conf);
649 	else if (strcmp(dir, ".timeout") == 0)
650 		error = parse_dir_timeout(conf);
651 	else {
652 		printf("mountroot: invalid directive `%s'\n", dir);
653 		/* Ignore the rest of the line. */
654 		(void)parse_skipto(conf, '\n');
655 		error = EINVAL;
656 	}
657 	free(dir, M_TEMP);
658 	return (error);
659 }
660 
661 static int
662 parse_mount_dev_present(const char *dev)
663 {
664 	struct nameidata nd;
665 	int error;
666 
667 	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, dev, curthread);
668 	error = namei(&nd);
669 	if (!error)
670 		vput(nd.ni_vp);
671 	NDFREE(&nd, NDF_ONLY_PNBUF);
672 	return (error != 0) ? 0 : 1;
673 }
674 
675 #define	ERRMSGL	255
676 static int
677 parse_mount(char **conf)
678 {
679 	char *errmsg;
680 	struct mntarg *ma;
681 	char *dev, *fs, *opts, *tok;
682 	int delay, error, timeout;
683 
684 	error = parse_token(conf, &tok);
685 	if (error)
686 		return (error);
687 	fs = tok;
688 	error = parse_skipto(&tok, ':');
689 	if (error) {
690 		free(fs, M_TEMP);
691 		return (error);
692 	}
693 	parse_poke(&tok, '\0');
694 	parse_advance(&tok);
695 	dev = tok;
696 
697 	if (root_mount_mddev != -1) {
698 		/* Handle substitution for the md unit number. */
699 		tok = strstr(dev, "md#");
700 		if (tok != NULL)
701 			tok[2] = '0' + root_mount_mddev;
702 	}
703 
704 	/* Parse options. */
705 	error = parse_token(conf, &tok);
706 	opts = (error == 0) ? tok : NULL;
707 
708 	printf("Trying to mount root from %s:%s [%s]...\n", fs, dev,
709 	    (opts != NULL) ? opts : "");
710 
711 	errmsg = malloc(ERRMSGL, M_TEMP, M_WAITOK | M_ZERO);
712 
713 	if (vfs_byname(fs) == NULL) {
714 		strlcpy(errmsg, "unknown file system", sizeof(errmsg));
715 		error = ENOENT;
716 		goto out;
717 	}
718 
719 	if (strcmp(fs, "zfs") != 0 && dev[0] != '\0' &&
720 	    !parse_mount_dev_present(dev)) {
721 		printf("mountroot: waiting for device %s ...\n", dev);
722 		delay = hz / 10;
723 		timeout = root_mount_timeout * hz;
724 		do {
725 			pause("rmdev", delay);
726 			timeout -= delay;
727 		} while (timeout > 0 && !parse_mount_dev_present(dev));
728 		if (timeout <= 0) {
729 			error = ENODEV;
730 			goto out;
731 		}
732 	}
733 
734 	ma = NULL;
735 	ma = mount_arg(ma, "fstype", fs, -1);
736 	ma = mount_arg(ma, "fspath", "/", -1);
737 	ma = mount_arg(ma, "from", dev, -1);
738 	ma = mount_arg(ma, "errmsg", errmsg, ERRMSGL);
739 	ma = mount_arg(ma, "ro", NULL, 0);
740 	ma = parse_mountroot_options(ma, opts);
741 	error = kernel_mount(ma, MNT_ROOTFS);
742 
743  out:
744 	if (error) {
745 		printf("Mounting from %s:%s failed with error %d",
746 		    fs, dev, error);
747 		if (errmsg[0] != '\0')
748 			printf(": %s", errmsg);
749 		printf(".\n");
750 	}
751 	free(fs, M_TEMP);
752 	free(errmsg, M_TEMP);
753 	if (opts != NULL)
754 		free(opts, M_TEMP);
755 	/* kernel_mount can return -1 on error. */
756 	return ((error < 0) ? EDOOFUS : error);
757 }
758 #undef ERRMSGL
759 
760 static int
761 vfs_mountroot_parse(struct sbuf *sb, struct mount *mpdevfs)
762 {
763 	struct mount *mp;
764 	char *conf;
765 	int error;
766 
767 	root_mount_mddev = -1;
768 
769 retry:
770 	conf = sbuf_data(sb);
771 	mp = TAILQ_NEXT(mpdevfs, mnt_list);
772 	error = (mp == NULL) ? 0 : EDOOFUS;
773 	root_mount_onfail = A_CONTINUE;
774 	while (mp == NULL) {
775 		error = parse_skipto(&conf, CC_NONWHITESPACE);
776 		if (error == PE_EOL) {
777 			parse_advance(&conf);
778 			continue;
779 		}
780 		if (error < 0)
781 			break;
782 		switch (parse_peek(&conf)) {
783 		case '#':
784 			error = parse_skipto(&conf, '\n');
785 			break;
786 		case '.':
787 			error = parse_directive(&conf);
788 			break;
789 		default:
790 			error = parse_mount(&conf);
791 			break;
792 		}
793 		if (error < 0)
794 			break;
795 		/* Ignore any trailing garbage on the line. */
796 		if (parse_peek(&conf) != '\n') {
797 			printf("mountroot: advancing to next directive...\n");
798 			(void)parse_skipto(&conf, '\n');
799 		}
800 		mp = TAILQ_NEXT(mpdevfs, mnt_list);
801 	}
802 	if (mp != NULL)
803 		return (0);
804 
805 	/*
806 	 * We failed to mount (a new) root.
807 	 */
808 	switch (root_mount_onfail) {
809 	case A_CONTINUE:
810 		break;
811 	case A_PANIC:
812 		panic("mountroot: unable to (re-)mount root.");
813 		/* NOTREACHED */
814 	case A_RETRY:
815 		goto retry;
816 	case A_REBOOT:
817 		kern_reboot(RB_NOSYNC);
818 		/* NOTREACHED */
819 	}
820 
821 	return (error);
822 }
823 
824 static void
825 vfs_mountroot_conf0(struct sbuf *sb)
826 {
827 	char *s, *tok, *mnt, *opt;
828 	int error;
829 
830 	sbuf_printf(sb, ".onfail panic\n");
831 	sbuf_printf(sb, ".timeout %d\n", root_mount_timeout);
832 	if (boothowto & RB_ASKNAME)
833 		sbuf_printf(sb, ".ask\n");
834 #ifdef ROOTDEVNAME
835 	if (boothowto & RB_DFLTROOT)
836 		sbuf_printf(sb, "%s\n", ROOTDEVNAME);
837 #endif
838 	if (boothowto & RB_CDROM) {
839 		sbuf_printf(sb, "cd9660:/dev/cd0 ro\n");
840 		sbuf_printf(sb, ".timeout 0\n");
841 		sbuf_printf(sb, "cd9660:/dev/acd0 ro\n");
842 		sbuf_printf(sb, ".timeout %d\n", root_mount_timeout);
843 	}
844 	s = getenv("vfs.root.mountfrom");
845 	if (s != NULL) {
846 		opt = getenv("vfs.root.mountfrom.options");
847 		tok = s;
848 		error = parse_token(&tok, &mnt);
849 		while (!error) {
850 			sbuf_printf(sb, "%s %s\n", mnt,
851 			    (opt != NULL) ? opt : "");
852 			free(mnt, M_TEMP);
853 			error = parse_token(&tok, &mnt);
854 		}
855 		if (opt != NULL)
856 			freeenv(opt);
857 		freeenv(s);
858 	}
859 	if (rootdevnames[0] != NULL)
860 		sbuf_printf(sb, "%s\n", rootdevnames[0]);
861 	if (rootdevnames[1] != NULL)
862 		sbuf_printf(sb, "%s\n", rootdevnames[1]);
863 #ifdef ROOTDEVNAME
864 	if (!(boothowto & RB_DFLTROOT))
865 		sbuf_printf(sb, "%s\n", ROOTDEVNAME);
866 #endif
867 	if (!(boothowto & RB_ASKNAME))
868 		sbuf_printf(sb, ".ask\n");
869 }
870 
871 static int
872 vfs_mountroot_readconf(struct thread *td, struct sbuf *sb)
873 {
874 	static char buf[128];
875 	struct nameidata nd;
876 	off_t ofs;
877 	ssize_t resid;
878 	int error, flags, len;
879 
880 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, "/.mount.conf", td);
881 	flags = FREAD;
882 	error = vn_open(&nd, &flags, 0, NULL);
883 	if (error)
884 		return (error);
885 
886 	NDFREE(&nd, NDF_ONLY_PNBUF);
887 	ofs = 0;
888 	len = sizeof(buf) - 1;
889 	while (1) {
890 		error = vn_rdwr(UIO_READ, nd.ni_vp, buf, len, ofs,
891 		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
892 		    NOCRED, &resid, td);
893 		if (error)
894 			break;
895 		if (resid == len)
896 			break;
897 		buf[len - resid] = 0;
898 		sbuf_printf(sb, "%s", buf);
899 		ofs += len - resid;
900 	}
901 
902 	VOP_UNLOCK(nd.ni_vp, 0);
903 	vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
904 	return (error);
905 }
906 
907 static void
908 vfs_mountroot_wait(void)
909 {
910 	struct root_hold_token *h;
911 	struct timeval lastfail;
912 	int curfail;
913 
914 	curfail = 0;
915 	while (1) {
916 		DROP_GIANT();
917 		g_waitidle();
918 		PICKUP_GIANT();
919 		mtx_lock(&mountlist_mtx);
920 		if (LIST_EMPTY(&root_holds)) {
921 			mtx_unlock(&mountlist_mtx);
922 			break;
923 		}
924 		if (ppsratecheck(&lastfail, &curfail, 1)) {
925 			printf("Root mount waiting for:");
926 			LIST_FOREACH(h, &root_holds, list)
927 				printf(" %s", h->who);
928 			printf("\n");
929 		}
930 		msleep(&root_holds, &mountlist_mtx, PZERO | PDROP, "roothold",
931 		    hz);
932 	}
933 }
934 
935 void
936 vfs_mountroot(void)
937 {
938 	struct mount *mp;
939 	struct sbuf *sb;
940 	struct thread *td;
941 	time_t timebase;
942 	int error;
943 
944 	td = curthread;
945 
946 	vfs_mountroot_wait();
947 
948 	sb = sbuf_new_auto();
949 	vfs_mountroot_conf0(sb);
950 	sbuf_finish(sb);
951 
952 	error = vfs_mountroot_devfs(td, &mp);
953 	while (!error) {
954 		error = vfs_mountroot_parse(sb, mp);
955 		if (!error) {
956 			error = vfs_mountroot_shuffle(td, mp);
957 			if (!error) {
958 				sbuf_clear(sb);
959 				error = vfs_mountroot_readconf(td, sb);
960 				sbuf_finish(sb);
961 			}
962 		}
963 	}
964 
965 	sbuf_delete(sb);
966 
967 	/*
968 	 * Iterate over all currently mounted file systems and use
969 	 * the time stamp found to check and/or initialize the RTC.
970 	 * Call inittodr() only once and pass it the largest of the
971 	 * timestamps we encounter.
972 	 */
973 	timebase = 0;
974 	mtx_lock(&mountlist_mtx);
975 	mp = TAILQ_FIRST(&mountlist);
976 	while (mp != NULL) {
977 		if (mp->mnt_time > timebase)
978 			timebase = mp->mnt_time;
979 		mp = TAILQ_NEXT(mp, mnt_list);
980 	}
981 	mtx_unlock(&mountlist_mtx);
982 	inittodr(timebase);
983 
984 	/* Keep prison0's root in sync with the global rootvnode. */
985 	mtx_lock(&prison0.pr_mtx);
986 	prison0.pr_root = rootvnode;
987 	vref(prison0.pr_root);
988 	mtx_unlock(&prison0.pr_mtx);
989 
990 	mtx_lock(&mountlist_mtx);
991 	atomic_store_rel_int(&root_mount_complete, 1);
992 	wakeup(&root_mount_complete);
993 	mtx_unlock(&mountlist_mtx);
994 }
995 
996 static struct mntarg *
997 parse_mountroot_options(struct mntarg *ma, const char *options)
998 {
999 	char *p;
1000 	char *name, *name_arg;
1001 	char *val, *val_arg;
1002 	char *opts;
1003 
1004 	if (options == NULL || options[0] == '\0')
1005 		return (ma);
1006 
1007 	p = opts = strdup(options, M_MOUNT);
1008 	if (opts == NULL) {
1009 		return (ma);
1010 	}
1011 
1012 	while((name = strsep(&p, ",")) != NULL) {
1013 		if (name[0] == '\0')
1014 			break;
1015 
1016 		val = strchr(name, '=');
1017 		if (val != NULL) {
1018 			*val = '\0';
1019 			++val;
1020 		}
1021 		if( strcmp(name, "rw") == 0 ||
1022 		    strcmp(name, "noro") == 0) {
1023 			/*
1024 			 * The first time we mount the root file system,
1025 			 * we need to mount 'ro', so We need to ignore
1026 			 * 'rw' and 'noro' mount options.
1027 			 */
1028 			continue;
1029 		}
1030 		name_arg = strdup(name, M_MOUNT);
1031 		val_arg = NULL;
1032 		if (val != NULL)
1033 			val_arg = strdup(val, M_MOUNT);
1034 
1035 		ma = mount_arg(ma, name_arg, val_arg,
1036 		    (val_arg != NULL ? -1 : 0));
1037 	}
1038 	free(opts, M_MOUNT);
1039 	return (ma);
1040 }
1041