vfs_mount.c revision 58389 
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 58389 2000-03-20 16:28:35Z green $
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 <sys/param.h>
46#include <sys/kernel.h>
47#include <sys/systm.h>
48#include <sys/proc.h>
49#include <sys/vnode.h>
50#include <sys/mount.h>
51#include <sys/malloc.h>
52#include <sys/reboot.h>
53#include <sys/diskslice.h>
54#include <sys/disklabel.h>
55#include <sys/conf.h>
56#include <sys/cons.h>
57
58#include "opt_ddb.h"
59#ifdef DDB
60#include <ddb/ddb.h>
61#endif
62
63MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount structure");
64
65#define ROOTNAME	"root_device"
66
67struct vnode	*rootvnode;
68
69/*
70 * The root specifiers we will try if RB_CDROM is specified.
71 */
72static char *cdrom_rootdevnames[] = {
73	"cd9660:cd0a",
74	"cd9660:acd0a",
75	"cd9660:wcd0a",
76	NULL
77};
78
79static void	vfs_mountroot(void *junk);
80static int	vfs_mountroot_try(char *mountfrom);
81static int	vfs_mountroot_ask(void);
82static void	gets(char *cp);
83
84/* legacy find-root code */
85char		*rootdevnames[2] = {NULL, NULL};
86static int	setrootbyname(char *name);
87
88SYSINIT(mountroot, SI_SUB_MOUNT_ROOT, SI_ORDER_SECOND, vfs_mountroot, NULL);
89
90/*
91 * Find and mount the root filesystem
92 */
93static void
94vfs_mountroot(void *junk)
95{
96	int		i;
97
98	/*
99	 * The root filesystem information is compiled in, and we are
100	 * booted with instructions to use it.
101	 */
102#ifdef ROOTDEVNAME
103	if ((boothowto & RB_DFLTROOT) &&
104	    !vfs_mountroot_try(ROOTDEVNAME))
105		return;
106#endif
107	/*
108	 * We are booted with instructions to prompt for the root filesystem,
109	 * or to use the compiled-in default when it doesn't exist.
110	 */
111	if (boothowto & (RB_DFLTROOT | RB_ASKNAME)) {
112		if (!vfs_mountroot_ask())
113			return;
114	}
115
116	/*
117	 * We've been given the generic "use CDROM as root" flag.  This is
118	 * necessary because one media may be used in many different
119	 * devices, so we need to search for them.
120	 */
121	if (boothowto & RB_CDROM) {
122		for (i = 0; cdrom_rootdevnames[i] != NULL; i++) {
123			if (!vfs_mountroot_try(cdrom_rootdevnames[i]))
124				return;
125		}
126	}
127
128	/*
129	 * Try to use the value read by the loader from /etc/fstab, or
130	 * supplied via some other means.  This is the preferred
131	 * mechanism.
132	 */
133	if (!vfs_mountroot_try(getenv("vfs.root.mountfrom")))
134		return;
135
136	/*
137	 * Try values that may have been computed by the machine-dependant
138	 * legacy code.
139	 */
140	if (!vfs_mountroot_try(rootdevnames[0]))
141		return;
142	if (!vfs_mountroot_try(rootdevnames[1]))
143		return;
144
145	/*
146	 * If we have a compiled-in default, and haven't already tried it, try
147	 * it now.
148	 */
149#ifdef ROOTDEVNAME
150	if (!(boothowto & RB_DFLTROOT))
151		if (!vfs_mountroot_try(ROOTDEVNAME))
152			return;
153#endif
154
155	/*
156	 * Everything so far has failed, prompt on the console if we haven't
157	 * already tried that.
158	 */
159	if (!(boothowto & (RB_DFLTROOT | RB_ASKNAME)) && !vfs_mountroot_ask())
160		return;
161	panic("Root mount failed, startup aborted.");
162}
163
164/*
165 * Mount (mountfrom) as the root filesystem.
166 */
167static int
168vfs_mountroot_try(char *mountfrom)
169{
170        struct mount	*mp;
171	char		*vfsname, *path;
172	int		error;
173	char		patt[32];
174	int		s;
175
176	vfsname = NULL;
177	path    = NULL;
178	mp      = NULL;
179	error   = EINVAL;
180
181	if (mountfrom == NULL)
182		return(error);		/* don't complain */
183
184	s = splcam();			/* Overkill, but annoying without it */
185	printf("Mounting root from %s\n", mountfrom);
186	splx(s);
187
188	/* parse vfs name and path */
189	vfsname = malloc(MFSNAMELEN, M_MOUNT, M_WAITOK);
190	path = malloc(MNAMELEN, M_MOUNT, M_WAITOK);
191	vfsname[0] = path[0] = 0;
192	sprintf(patt, "%%%d[a-z0-9]:%%%ds", MFSNAMELEN, MNAMELEN);
193	if (sscanf(mountfrom, patt, vfsname, path) < 1)
194		goto done;
195
196	/* allocate a root mount */
197	error = vfs_rootmountalloc(vfsname, path[0] != 0 ? path : ROOTNAME,
198				   &mp);
199	if (error != 0) {
200		printf("Can't allocate root mount for filesystem '%s': %d\n",
201		       vfsname, error);
202		goto done;
203	}
204	mp->mnt_flag |= MNT_ROOTFS;
205
206	/* do our best to set rootdev */
207	if ((path[0] != 0) && setrootbyname(path))
208		printf("setrootbyname failed\n");
209
210	/* If the root device is a type "memory disk", mount RW */
211	if (rootdev != NODEV && devsw(rootdev) &&
212	    (devsw(rootdev)->d_flags & D_MEMDISK))
213		mp->mnt_flag &= ~MNT_RDONLY;
214
215	error = VFS_MOUNT(mp, NULL, NULL, NULL, curproc);
216
217done:
218	if (vfsname != NULL)
219		free(vfsname, M_MOUNT);
220	if (path != NULL)
221		free(path, M_MOUNT);
222	if (error != 0) {
223		if (mp != NULL) {
224			vfs_unbusy(mp, curproc);
225			free(mp, M_MOUNT);
226		}
227		printf("Root mount failed: %d\n", error);
228	} else {
229
230		/* register with list of mounted filesystems */
231		simple_lock(&mountlist_slock);
232		TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
233		simple_unlock(&mountlist_slock);
234
235		/* sanity check system clock against root filesystem timestamp */
236		inittodr(mp->mnt_time);
237		vfs_unbusy(mp, curproc);
238	}
239	return(error);
240}
241
242/*
243 * Spin prompting on the console for a suitable root filesystem
244 */
245static int
246vfs_mountroot_ask(void)
247{
248	char name[128];
249	int i;
250	dev_t dev;
251
252	for(;;) {
253		printf("\nManual root filesystem specification:\n");
254		printf("  <fstype>:<device>  Mount <device> using filesystem <fstype>\n");
255		printf("                       eg. ufs:/dev/da0s1a\n");
256		printf("  ?                  List valid disk boot devices\n");
257		printf("  <empty line>       Abort manual input\n");
258		printf("\nmountroot> ");
259		gets(name);
260		if (name[0] == 0)
261			return(1);
262		if (name[0] == '?') {
263			printf("Possibly valid devices for 'ufs' root:\n");
264			for (i = 0; i < NUMCDEVSW; i++) {
265				dev = makedev(i, 0);
266				if (devsw(dev) != NULL)
267					printf(" \"%s\"", devsw(dev)->d_name);
268			}
269			printf("\n");
270			continue;
271		}
272		if (!vfs_mountroot_try(name))
273			return(0);
274	}
275}
276
277static void
278gets(char *cp)
279{
280	char *lp;
281	int c;
282
283	lp = cp;
284	for (;;) {
285		printf("%c", c = cngetc() & 0177);
286		switch (c) {
287		case -1:
288		case '\n':
289		case '\r':
290			*lp++ = '\0';
291			return;
292		case '\b':
293		case '\177':
294			if (lp > cp) {
295				printf(" \b");
296				lp--;
297			}
298			continue;
299		case '#':
300			lp--;
301			if (lp < cp)
302				lp = cp;
303			continue;
304		case '@':
305		case 'u' & 037:
306			lp = cp;
307			printf("%c", '\n');
308			continue;
309		default:
310			*lp++ = c;
311		}
312	}
313}
314
315/*
316 * Convert a given name to the dev_t of the disk-like device
317 * it refers to.
318 */
319dev_t
320getdiskbyname(char *name) {
321	char *cp;
322	int cd, unit, slice, part;
323	dev_t dev;
324
325	slice = 0;
326	part = 0;
327	cp = rindex(name, '/');
328	if (cp != NULL) {
329		name = cp + 1;
330	}
331	cp = name;
332	while (cp != '\0' && (*cp < '0' || *cp > '9'))
333		cp++;
334	if (cp == name) {
335		printf("missing device name\n");
336		return (NODEV);
337	}
338	if (*cp == '\0') {
339		printf("missing unit number\n");
340		return (NODEV);
341	}
342	unit = *cp - '0';
343	*cp++ = '\0';
344	for (cd = 0; cd < NUMCDEVSW; cd++) {
345		dev = makedev(cd, 0);
346		if (devsw(dev) != NULL &&
347		    strcmp(devsw(dev)->d_name, name) == 0)
348			goto gotit;
349	}
350	printf("no such device '%s'\n", name);
351	return (NODEV);
352gotit:
353	while (*cp >= '0' && *cp <= '9')
354		unit += 10 * unit + *cp++ - '0';
355	if (*cp == 's' && cp[1] >= '0' && cp[1] <= '9') {
356		slice = cp[1] - '0' + 1;
357		cp += 2;
358	}
359	if (*cp >= 'a' && *cp <= 'h') {
360		part = *cp - 'a';
361		cp++;
362	}
363	if (*cp != '\0') {
364		printf("junk after name\n");
365		return (NODEV);
366	}
367	return (makedev(cd, dkmakeminor(unit, slice, part)));
368}
369
370/*
371 * Set rootdev to match (name), given that we expect it to
372 * refer to a disk-like device.
373 */
374static int
375setrootbyname(char *name)
376{
377	dev_t diskdev;
378
379	diskdev = getdiskbyname(name);
380	if (diskdev != NODEV) {
381		rootdev = diskdev;
382		return (0);
383	}
384
385	return (1);
386}
387
388#ifdef DDB
389DB_SHOW_COMMAND(disk, db_getdiskbyname)
390{
391	dev_t dev;
392
393	if (modif[0] == '\0') {
394		db_error("usage: show disk/devicename");
395		return;
396	}
397	dev = getdiskbyname(modif);
398	if (dev != NODEV)
399		db_printf("dev_t = %p\n", dev);
400	else
401		db_printf("No disk device matched.\n");
402}
403#endif
404