vfs_mount.c revision 66615 
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 66615 2000-10-04 01:29:17Z jasone $
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/kernel.h>
49#include <sys/systm.h>
50#include <sys/proc.h>
51#include <sys/vnode.h>
52#include <sys/mount.h>
53#include <sys/malloc.h>
54#include <sys/reboot.h>
55#include <sys/diskslice.h>
56#include <sys/disklabel.h>
57#include <sys/conf.h>
58#include <sys/cons.h>
59
60#include "opt_ddb.h"
61#ifdef DDB
62#include <ddb/ddb.h>
63#endif
64
65MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount structure");
66
67#define ROOTNAME	"root_device"
68
69struct vnode	*rootvnode;
70
71/*
72 * The root specifiers we will try if RB_CDROM is specified.
73 */
74static char *cdrom_rootdevnames[] = {
75	"cd9660:cd0a",
76	"cd9660:acd0a",
77	"cd9660:wcd0a",
78	NULL
79};
80
81static void	vfs_mountroot(void *junk);
82static int	vfs_mountroot_try(char *mountfrom);
83static int	vfs_mountroot_ask(void);
84static void	gets(char *cp);
85
86/* legacy find-root code */
87char		*rootdevnames[2] = {NULL, NULL};
88static int	setrootbyname(char *name);
89
90SYSINIT(mountroot, SI_SUB_MOUNT_ROOT, SI_ORDER_SECOND, vfs_mountroot, NULL);
91
92/*
93 * Find and mount the root filesystem
94 */
95static void
96vfs_mountroot(void *junk)
97{
98	int		i;
99
100	/*
101	 * The root filesystem information is compiled in, and we are
102	 * booted with instructions to use it.
103	 */
104#ifdef ROOTDEVNAME
105	if ((boothowto & RB_DFLTROOT) &&
106	    !vfs_mountroot_try(ROOTDEVNAME))
107		return;
108#endif
109	/*
110	 * We are booted with instructions to prompt for the root filesystem,
111	 * or to use the compiled-in default when it doesn't exist.
112	 */
113	if (boothowto & (RB_DFLTROOT | RB_ASKNAME)) {
114		if (!vfs_mountroot_ask())
115			return;
116	}
117
118	/*
119	 * We've been given the generic "use CDROM as root" flag.  This is
120	 * necessary because one media may be used in many different
121	 * devices, so we need to search for them.
122	 */
123	if (boothowto & RB_CDROM) {
124		for (i = 0; cdrom_rootdevnames[i] != NULL; i++) {
125			if (!vfs_mountroot_try(cdrom_rootdevnames[i]))
126				return;
127		}
128	}
129
130	/*
131	 * Try to use the value read by the loader from /etc/fstab, or
132	 * supplied via some other means.  This is the preferred
133	 * mechanism.
134	 */
135	if (!vfs_mountroot_try(getenv("vfs.root.mountfrom")))
136		return;
137
138	/*
139	 * Try values that may have been computed by the machine-dependant
140	 * legacy code.
141	 */
142	if (!vfs_mountroot_try(rootdevnames[0]))
143		return;
144	if (!vfs_mountroot_try(rootdevnames[1]))
145		return;
146
147	/*
148	 * If we have a compiled-in default, and haven't already tried it, try
149	 * it now.
150	 */
151#ifdef ROOTDEVNAME
152	if (!(boothowto & RB_DFLTROOT))
153		if (!vfs_mountroot_try(ROOTDEVNAME))
154			return;
155#endif
156
157	/*
158	 * Everything so far has failed, prompt on the console if we haven't
159	 * already tried that.
160	 */
161	if (!(boothowto & (RB_DFLTROOT | RB_ASKNAME)) && !vfs_mountroot_ask())
162		return;
163	panic("Root mount failed, startup aborted.");
164}
165
166/*
167 * Mount (mountfrom) as the root filesystem.
168 */
169static int
170vfs_mountroot_try(char *mountfrom)
171{
172        struct mount	*mp;
173	char		*vfsname, *path;
174	int		error;
175	char		patt[32];
176	int		s;
177
178	vfsname = NULL;
179	path    = NULL;
180	mp      = NULL;
181	error   = EINVAL;
182
183	if (mountfrom == NULL)
184		return(error);		/* don't complain */
185
186	s = splcam();			/* Overkill, but annoying without it */
187	printf("Mounting root from %s\n", mountfrom);
188	splx(s);
189
190	/* parse vfs name and path */
191	vfsname = malloc(MFSNAMELEN, M_MOUNT, M_WAITOK);
192	path = malloc(MNAMELEN, M_MOUNT, M_WAITOK);
193	vfsname[0] = path[0] = 0;
194	sprintf(patt, "%%%d[a-z0-9]:%%%ds", MFSNAMELEN, MNAMELEN);
195	if (sscanf(mountfrom, patt, vfsname, path) < 1)
196		goto done;
197
198	/* allocate a root mount */
199	error = vfs_rootmountalloc(vfsname, path[0] != 0 ? path : ROOTNAME,
200				   &mp);
201	if (error != 0) {
202		printf("Can't allocate root mount for filesystem '%s': %d\n",
203		       vfsname, error);
204		goto done;
205	}
206	mp->mnt_flag |= MNT_ROOTFS;
207
208	/* do our best to set rootdev */
209	if ((path[0] != 0) && setrootbyname(path))
210		printf("setrootbyname failed\n");
211
212	/* If the root device is a type "memory disk", mount RW */
213	if (rootdev != NODEV && devsw(rootdev) &&
214	    (devsw(rootdev)->d_flags & D_MEMDISK))
215		mp->mnt_flag &= ~MNT_RDONLY;
216
217	error = VFS_MOUNT(mp, NULL, NULL, NULL, curproc);
218
219done:
220	if (vfsname != NULL)
221		free(vfsname, M_MOUNT);
222	if (path != NULL)
223		free(path, M_MOUNT);
224	if (error != 0) {
225		if (mp != NULL) {
226			vfs_unbusy(mp, curproc);
227			free(mp, M_MOUNT);
228		}
229		printf("Root mount failed: %d\n", error);
230	} else {
231
232		/* register with list of mounted filesystems */
233		mtx_enter(&mountlist_mtx, MTX_DEF);
234		TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
235		mtx_exit(&mountlist_mtx, MTX_DEF);
236
237		/* sanity check system clock against root filesystem timestamp */
238		inittodr(mp->mnt_time);
239		vfs_unbusy(mp, curproc);
240	}
241	return(error);
242}
243
244/*
245 * Spin prompting on the console for a suitable root filesystem
246 */
247static int
248vfs_mountroot_ask(void)
249{
250	char name[128];
251	int i;
252	dev_t dev;
253
254	for(;;) {
255		printf("\nManual root filesystem specification:\n");
256		printf("  <fstype>:<device>  Mount <device> using filesystem <fstype>\n");
257		printf("                       eg. ufs:/dev/da0s1a\n");
258		printf("  ?                  List valid disk boot devices\n");
259		printf("  <empty line>       Abort manual input\n");
260		printf("\nmountroot> ");
261		gets(name);
262		if (name[0] == 0)
263			return(1);
264		if (name[0] == '?') {
265			printf("Possibly valid devices for 'ufs' root:\n");
266			for (i = 0; i < NUMCDEVSW; i++) {
267				dev = makedev(i, 0);
268				if (devsw(dev) != NULL)
269					printf(" \"%s\"", devsw(dev)->d_name);
270			}
271			printf("\n");
272			continue;
273		}
274		if (!vfs_mountroot_try(name))
275			return(0);
276	}
277}
278
279static void
280gets(char *cp)
281{
282	char *lp;
283	int c;
284
285	lp = cp;
286	for (;;) {
287		printf("%c", c = cngetc() & 0177);
288		switch (c) {
289		case -1:
290		case '\n':
291		case '\r':
292			*lp++ = '\0';
293			return;
294		case '\b':
295		case '\177':
296			if (lp > cp) {
297				printf(" \b");
298				lp--;
299			}
300			continue;
301		case '#':
302			lp--;
303			if (lp < cp)
304				lp = cp;
305			continue;
306		case '@':
307		case 'u' & 037:
308			lp = cp;
309			printf("%c", '\n');
310			continue;
311		default:
312			*lp++ = c;
313		}
314	}
315}
316
317/*
318 * Convert a given name to the dev_t of the disk-like device
319 * it refers to.
320 */
321dev_t
322getdiskbyname(char *name) {
323	char *cp;
324	dev_t dev;
325
326	cp = name;
327	if (!bcmp(cp, "/dev/", 5))
328		cp += 5;
329
330	dev = NODEV;
331	EVENTHANDLER_INVOKE(dev_clone, cp, strlen(cp), &dev);
332	return (dev);
333}
334
335/*
336 * Set rootdev to match (name), given that we expect it to
337 * refer to a disk-like device.
338 */
339static int
340setrootbyname(char *name)
341{
342	dev_t diskdev;
343
344	diskdev = getdiskbyname(name);
345	if (diskdev != NODEV) {
346		rootdev = diskdev;
347		return (0);
348	}
349
350	return (1);
351}
352
353#ifdef DDB
354DB_SHOW_COMMAND(disk, db_getdiskbyname)
355{
356	dev_t dev;
357
358	if (modif[0] == '\0') {
359		db_error("usage: show disk/devicename");
360		return;
361	}
362	dev = getdiskbyname(modif);
363	if (dev != NODEV)
364		db_printf("dev_t = %p\n", dev);
365	else
366		db_printf("No disk device matched.\n");
367}
368#endif
369