vfs_mount.c revision 91859 
1/*-
2 * Copyright (c) 1999 Michael Smith
3 * All rights reserved.
4 * Copyright (c) 1999 Poul-Henning Kamp
5 * 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 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 *	$FreeBSD: head/sys/kern/vfs_mount.c 91859 2002-03-08 10:33:11Z phk $
29 */
30
31/*
32 * Locate and mount the root filesystem.
33 *
34 * The root filesystem is detailed in the kernel environment variable
35 * vfs.root.mountfrom, which is expected to be in the general format
36 *
37 * <vfsname>:[<path>]
38 * vfsname   := the name of a VFS known to the kernel and capable
39 *              of being mounted as root
40 * path      := disk device name or other data used by the filesystem
41 *              to locate its physical store
42 *
43 */
44
45#include "opt_rootdevname.h"
46
47#include <sys/param.h>
48#include <sys/systm.h>
49#include <sys/kernel.h>
50#include <sys/lock.h>
51#include <sys/mutex.h>
52#include <sys/vnode.h>
53#include <sys/mount.h>
54#include <sys/malloc.h>
55#include <sys/reboot.h>
56#include <sys/diskslice.h>
57#include <sys/disklabel.h>
58#include <sys/conf.h>
59#include <sys/cons.h>
60#include <sys/proc.h>
61
62#include "opt_ddb.h"
63
64#ifdef DDB
65#include <ddb/ddb.h>
66#endif
67
68#include <paths.h>
69
70MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount structure");
71
72#define ROOTNAME	"root_device"
73
74/*
75 * The vnode of the system's root (/ in the filesystem, without chroot
76 * active.)
77 */
78struct vnode	*rootvnode;
79
80/*
81 * The root specifiers we will try if RB_CDROM is specified.
82 */
83static char *cdrom_rootdevnames[] = {
84	"cd9660:cd0a",
85	"cd9660:acd0a",
86	"cd9660:wcd0a",
87	NULL
88};
89
90static int	vfs_mountroot_try(char *mountfrom);
91static int	vfs_mountroot_ask(void);
92static void	gets(char *cp);
93
94/* legacy find-root code */
95char		*rootdevnames[2] = {NULL, NULL};
96static int	setrootbyname(char *name);
97
98/*
99 * Find and mount the root filesystem
100 */
101void
102vfs_mountroot(void *foo __unused)
103{
104	int		i;
105
106	/*
107	 * The root filesystem information is compiled in, and we are
108	 * booted with instructions to use it.
109	 */
110#ifdef ROOTDEVNAME
111	if ((boothowto & RB_DFLTROOT) &&
112	    !vfs_mountroot_try(ROOTDEVNAME))
113		return;
114#endif
115	/*
116	 * We are booted with instructions to prompt for the root filesystem,
117	 * or to use the compiled-in default when it doesn't exist.
118	 */
119	if (boothowto & (RB_DFLTROOT | RB_ASKNAME)) {
120		if (!vfs_mountroot_ask())
121			return;
122	}
123
124	/*
125	 * We've been given the generic "use CDROM as root" flag.  This is
126	 * necessary because one media may be used in many different
127	 * devices, so we need to search for them.
128	 */
129	if (boothowto & RB_CDROM) {
130		for (i = 0; cdrom_rootdevnames[i] != NULL; i++) {
131			if (!vfs_mountroot_try(cdrom_rootdevnames[i]))
132				return;
133		}
134	}
135
136	/*
137	 * Try to use the value read by the loader from /etc/fstab, or
138	 * supplied via some other means.  This is the preferred
139	 * mechanism.
140	 */
141	if (!vfs_mountroot_try(getenv("vfs.root.mountfrom")))
142		return;
143
144	/*
145	 * Try values that may have been computed by the machine-dependant
146	 * legacy code.
147	 */
148	if (!vfs_mountroot_try(rootdevnames[0]))
149		return;
150	if (!vfs_mountroot_try(rootdevnames[1]))
151		return;
152
153	/*
154	 * If we have a compiled-in default, and haven't already tried it, try
155	 * it now.
156	 */
157#ifdef ROOTDEVNAME
158	if (!(boothowto & RB_DFLTROOT))
159		if (!vfs_mountroot_try(ROOTDEVNAME))
160			return;
161#endif
162
163	/*
164	 * Everything so far has failed, prompt on the console if we haven't
165	 * already tried that.
166	 */
167	if (!(boothowto & (RB_DFLTROOT | RB_ASKNAME)) && !vfs_mountroot_ask())
168		return;
169	panic("Root mount failed, startup aborted.");
170}
171
172/*
173 * Mount (mountfrom) as the root filesystem.
174 */
175static int
176vfs_mountroot_try(char *mountfrom)
177{
178        struct mount	*mp;
179	char		*vfsname, *path;
180	int		error;
181	char		patt[32];
182	int		s;
183
184	vfsname = NULL;
185	path    = NULL;
186	mp      = NULL;
187	error   = EINVAL;
188
189	if (mountfrom == NULL)
190		return(error);		/* don't complain */
191
192	s = splcam();			/* Overkill, but annoying without it */
193	printf("Mounting root from %s\n", mountfrom);
194	splx(s);
195
196	/* parse vfs name and path */
197	vfsname = malloc(MFSNAMELEN, M_MOUNT, M_WAITOK);
198	path = malloc(MNAMELEN, M_MOUNT, M_WAITOK);
199	vfsname[0] = path[0] = 0;
200	sprintf(patt, "%%%d[a-z0-9]:%%%ds", MFSNAMELEN, MNAMELEN);
201	if (sscanf(mountfrom, patt, vfsname, path) < 1)
202		goto done;
203
204	/* allocate a root mount */
205	error = vfs_rootmountalloc(vfsname, path[0] != 0 ? path : ROOTNAME,
206				   &mp);
207	if (error != 0) {
208		printf("Can't allocate root mount for filesystem '%s': %d\n",
209		       vfsname, error);
210		goto done;
211	}
212	mp->mnt_flag |= MNT_ROOTFS;
213
214	/* do our best to set rootdev */
215	if ((path[0] != 0) && setrootbyname(path))
216		printf("setrootbyname failed\n");
217
218	/* If the root device is a type "memory disk", mount RW */
219	if (rootdev != NODEV && devsw(rootdev) &&
220	    (devsw(rootdev)->d_flags & D_MEMDISK))
221		mp->mnt_flag &= ~MNT_RDONLY;
222
223	/*
224	 * Set the mount path to be something useful, because the
225	 * filesystem code isn't responsible now for initialising
226	 * f_mntonname unless they want to override the default
227	 * (which is `path'.)
228	 */
229	strncpy(mp->mnt_stat.f_mntonname, "/", MNAMELEN);
230
231	error = VFS_MOUNT(mp, NULL, NULL, NULL, curthread);
232
233done:
234	if (vfsname != NULL)
235		free(vfsname, M_MOUNT);
236	if (path != NULL)
237		free(path, M_MOUNT);
238	if (error != 0) {
239		if (mp != NULL) {
240			vfs_unbusy(mp, curthread);
241			free(mp, M_MOUNT);
242		}
243		printf("Root mount failed: %d\n", error);
244	} else {
245
246		/* register with list of mounted filesystems */
247		mtx_lock(&mountlist_mtx);
248		TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
249		mtx_unlock(&mountlist_mtx);
250
251		/* sanity check system clock against root filesystem timestamp */
252		inittodr(mp->mnt_time);
253		vfs_unbusy(mp, curthread);
254	}
255	return(error);
256}
257
258/*
259 * Spin prompting on the console for a suitable root filesystem
260 */
261static int
262vfs_mountroot_ask(void)
263{
264	char name[128];
265	int i;
266	dev_t dev;
267
268	for(;;) {
269		printf("\nManual root filesystem specification:\n");
270		printf("  <fstype>:<device>  Mount <device> using filesystem <fstype>\n");
271#if defined(__i386__) || defined(__ia64__)
272		printf("                       eg. ufs:da0s1a\n");
273#else
274		printf("                       eg. ufs:da0a\n");
275#endif
276		printf("  ?                  List valid disk boot devices\n");
277		printf("  <empty line>       Abort manual input\n");
278		printf("\nmountroot> ");
279		gets(name);
280		if (name[0] == 0)
281			return(1);
282		if (name[0] == '?') {
283			printf("Possibly valid devices for 'ufs' root:\n");
284			for (i = 0; i < NUMCDEVSW; i++) {
285				dev = makedev(i, 0);
286				if (devsw(dev) != NULL)
287					printf(" \"%s\"", devsw(dev)->d_name);
288			}
289			printf("\n");
290			continue;
291		}
292		if (!vfs_mountroot_try(name))
293			return(0);
294	}
295}
296
297/*
298 * Local helper function for vfs_mountroot_ask.
299 */
300static void
301gets(char *cp)
302{
303	char *lp;
304	int c;
305
306	lp = cp;
307	for (;;) {
308		printf("%c", c = cngetc() & 0177);
309		switch (c) {
310		case -1:
311		case '\n':
312		case '\r':
313			*lp++ = '\0';
314			return;
315		case '\b':
316		case '\177':
317			if (lp > cp) {
318				printf(" \b");
319				lp--;
320			}
321			continue;
322		case '#':
323			lp--;
324			if (lp < cp)
325				lp = cp;
326			continue;
327		case '@':
328		case 'u' & 037:
329			lp = cp;
330			printf("%c", '\n');
331			continue;
332		default:
333			*lp++ = c;
334		}
335	}
336}
337
338/*
339 * Convert a given name to the dev_t of the disk-like device
340 * it refers to.
341 */
342dev_t
343getdiskbyname(char *name) {
344	char *cp;
345	dev_t dev;
346
347	cp = name;
348	if (!bcmp(cp, "/dev/", 5))
349		cp += 5;
350
351	dev = NODEV;
352	EVENTHANDLER_INVOKE(dev_clone, cp, strlen(cp), &dev);
353	return (dev);
354}
355
356/*
357 * Set rootdev to match (name), given that we expect it to
358 * refer to a disk-like device.
359 */
360static int
361setrootbyname(char *name)
362{
363	dev_t diskdev;
364
365	diskdev = getdiskbyname(name);
366	if (diskdev != NODEV) {
367		rootdev = diskdev;
368		return (0);
369	}
370
371	return (1);
372}
373
374/* Show the dev_t for a disk specified by name */
375#ifdef DDB
376DB_SHOW_COMMAND(disk, db_getdiskbyname)
377{
378	dev_t dev;
379
380	if (modif[0] == '\0') {
381		db_error("usage: show disk/devicename");
382		return;
383	}
384	dev = getdiskbyname(modif);
385	if (dev != NODEV)
386		db_printf("dev_t = %p\n", dev);
387	else
388		db_printf("No disk device matched.\n");
389}
390#endif
391