vfs_mount.c revision 67882 
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 67882 2000-10-29 13:57:19Z 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/kernel.h>
49#include <sys/systm.h>
50#include <sys/vnode.h>
51#include <sys/mount.h>
52#include <sys/malloc.h>
53#include <sys/reboot.h>
54#include <sys/diskslice.h>
55#include <sys/disklabel.h>
56#include <sys/conf.h>
57#include <sys/cons.h>
58
59#include "opt_ddb.h"
60#ifdef DDB
61#include <ddb/ddb.h>
62#endif
63
64MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount structure");
65
66#define ROOTNAME	"root_device"
67
68struct vnode	*rootvnode;
69
70/*
71 * The root specifiers we will try if RB_CDROM is specified.
72 */
73static char *cdrom_rootdevnames[] = {
74	"cd9660:cd0a",
75	"cd9660:acd0a",
76	"cd9660:wcd0a",
77	NULL
78};
79
80static void	vfs_mountroot(void *junk);
81static int	vfs_mountroot_try(char *mountfrom);
82static int	vfs_mountroot_ask(void);
83static void	gets(char *cp);
84
85/* legacy find-root code */
86char		*rootdevnames[2] = {NULL, NULL};
87static int	setrootbyname(char *name);
88
89SYSINIT(mountroot, SI_SUB_MOUNT_ROOT, SI_ORDER_SECOND, vfs_mountroot, NULL);
90
91/*
92 * Find and mount the root filesystem
93 */
94static void
95vfs_mountroot(void *junk)
96{
97	int		i;
98
99	/*
100	 * The root filesystem information is compiled in, and we are
101	 * booted with instructions to use it.
102	 */
103#ifdef ROOTDEVNAME
104	if ((boothowto & RB_DFLTROOT) &&
105	    !vfs_mountroot_try(ROOTDEVNAME))
106		return;
107#endif
108	/*
109	 * We are booted with instructions to prompt for the root filesystem,
110	 * or to use the compiled-in default when it doesn't exist.
111	 */
112	if (boothowto & (RB_DFLTROOT | RB_ASKNAME)) {
113		if (!vfs_mountroot_ask())
114			return;
115	}
116
117	/*
118	 * We've been given the generic "use CDROM as root" flag.  This is
119	 * necessary because one media may be used in many different
120	 * devices, so we need to search for them.
121	 */
122	if (boothowto & RB_CDROM) {
123		for (i = 0; cdrom_rootdevnames[i] != NULL; i++) {
124			if (!vfs_mountroot_try(cdrom_rootdevnames[i]))
125				return;
126		}
127	}
128
129	/*
130	 * Try to use the value read by the loader from /etc/fstab, or
131	 * supplied via some other means.  This is the preferred
132	 * mechanism.
133	 */
134	if (!vfs_mountroot_try(getenv("vfs.root.mountfrom")))
135		return;
136
137	/*
138	 * Try values that may have been computed by the machine-dependant
139	 * legacy code.
140	 */
141	if (!vfs_mountroot_try(rootdevnames[0]))
142		return;
143	if (!vfs_mountroot_try(rootdevnames[1]))
144		return;
145
146	/*
147	 * If we have a compiled-in default, and haven't already tried it, try
148	 * it now.
149	 */
150#ifdef ROOTDEVNAME
151	if (!(boothowto & RB_DFLTROOT))
152		if (!vfs_mountroot_try(ROOTDEVNAME))
153			return;
154#endif
155
156	/*
157	 * Everything so far has failed, prompt on the console if we haven't
158	 * already tried that.
159	 */
160	if (!(boothowto & (RB_DFLTROOT | RB_ASKNAME)) && !vfs_mountroot_ask())
161		return;
162	panic("Root mount failed, startup aborted.");
163}
164
165/*
166 * Mount (mountfrom) as the root filesystem.
167 */
168static int
169vfs_mountroot_try(char *mountfrom)
170{
171        struct mount	*mp;
172	char		*vfsname, *path;
173	int		error;
174	char		patt[32];
175	int		s;
176
177	vfsname = NULL;
178	path    = NULL;
179	mp      = NULL;
180	error   = EINVAL;
181
182	if (mountfrom == NULL)
183		return(error);		/* don't complain */
184
185	s = splcam();			/* Overkill, but annoying without it */
186	printf("Mounting root from %s\n", mountfrom);
187	splx(s);
188
189	/* parse vfs name and path */
190	vfsname = malloc(MFSNAMELEN, M_MOUNT, M_WAITOK);
191	path = malloc(MNAMELEN, M_MOUNT, M_WAITOK);
192	vfsname[0] = path[0] = 0;
193	sprintf(patt, "%%%d[a-z0-9]:%%%ds", MFSNAMELEN, MNAMELEN);
194	if (sscanf(mountfrom, patt, vfsname, path) < 1)
195		goto done;
196
197	/* allocate a root mount */
198	error = vfs_rootmountalloc(vfsname, path[0] != 0 ? path : ROOTNAME,
199				   &mp);
200	if (error != 0) {
201		printf("Can't allocate root mount for filesystem '%s': %d\n",
202		       vfsname, error);
203		goto done;
204	}
205	mp->mnt_flag |= MNT_ROOTFS;
206
207	/* do our best to set rootdev */
208	if ((path[0] != 0) && setrootbyname(path))
209		printf("setrootbyname failed\n");
210
211	/* If the root device is a type "memory disk", mount RW */
212	if (rootdev != NODEV && devsw(rootdev) &&
213	    (devsw(rootdev)->d_flags & D_MEMDISK))
214		mp->mnt_flag &= ~MNT_RDONLY;
215
216	error = VFS_MOUNT(mp, NULL, NULL, NULL, curproc);
217
218done:
219	if (vfsname != NULL)
220		free(vfsname, M_MOUNT);
221	if (path != NULL)
222		free(path, M_MOUNT);
223	if (error != 0) {
224		if (mp != NULL) {
225			vfs_unbusy(mp, curproc);
226			free(mp, M_MOUNT);
227		}
228		printf("Root mount failed: %d\n", error);
229	} else {
230
231		/* register with list of mounted filesystems */
232		mtx_enter(&mountlist_mtx, MTX_DEF);
233		TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
234		mtx_exit(&mountlist_mtx, MTX_DEF);
235
236		/* sanity check system clock against root filesystem timestamp */
237		inittodr(mp->mnt_time);
238		vfs_unbusy(mp, curproc);
239	}
240	return(error);
241}
242
243/*
244 * Spin prompting on the console for a suitable root filesystem
245 */
246static int
247vfs_mountroot_ask(void)
248{
249	char name[128];
250	int i;
251	dev_t dev;
252
253	for(;;) {
254		printf("\nManual root filesystem specification:\n");
255		printf("  <fstype>:<device>  Mount <device> using filesystem <fstype>\n");
256		printf("                       eg. ufs:/dev/da0s1a\n");
257		printf("  ?                  List valid disk boot devices\n");
258		printf("  <empty line>       Abort manual input\n");
259		printf("\nmountroot> ");
260		gets(name);
261		if (name[0] == 0)
262			return(1);
263		if (name[0] == '?') {
264			printf("Possibly valid devices for 'ufs' root:\n");
265			for (i = 0; i < NUMCDEVSW; i++) {
266				dev = makedev(i, 0);
267				if (devsw(dev) != NULL)
268					printf(" \"%s\"", devsw(dev)->d_name);
269			}
270			printf("\n");
271			continue;
272		}
273		if (!vfs_mountroot_try(name))
274			return(0);
275	}
276}
277
278static void
279gets(char *cp)
280{
281	char *lp;
282	int c;
283
284	lp = cp;
285	for (;;) {
286		printf("%c", c = cngetc() & 0177);
287		switch (c) {
288		case -1:
289		case '\n':
290		case '\r':
291			*lp++ = '\0';
292			return;
293		case '\b':
294		case '\177':
295			if (lp > cp) {
296				printf(" \b");
297				lp--;
298			}
299			continue;
300		case '#':
301			lp--;
302			if (lp < cp)
303				lp = cp;
304			continue;
305		case '@':
306		case 'u' & 037:
307			lp = cp;
308			printf("%c", '\n');
309			continue;
310		default:
311			*lp++ = c;
312		}
313	}
314}
315
316/*
317 * Convert a given name to the dev_t of the disk-like device
318 * it refers to.
319 */
320dev_t
321getdiskbyname(char *name) {
322	char *cp;
323	dev_t dev;
324
325	cp = name;
326	if (!bcmp(cp, "/dev/", 5))
327		cp += 5;
328
329	dev = NODEV;
330	EVENTHANDLER_INVOKE(dev_clone, cp, strlen(cp), &dev);
331	return (dev);
332}
333
334/*
335 * Set rootdev to match (name), given that we expect it to
336 * refer to a disk-like device.
337 */
338static int
339setrootbyname(char *name)
340{
341	dev_t diskdev;
342
343	diskdev = getdiskbyname(name);
344	if (diskdev != NODEV) {
345		rootdev = diskdev;
346		return (0);
347	}
348
349	return (1);
350}
351
352#ifdef DDB
353DB_SHOW_COMMAND(disk, db_getdiskbyname)
354{
355	dev_t dev;
356
357	if (modif[0] == '\0') {
358		db_error("usage: show disk/devicename");
359		return;
360	}
361	dev = getdiskbyname(modif);
362	if (dev != NODEV)
363		db_printf("dev_t = %p\n", dev);
364	else
365		db_printf("No disk device matched.\n");
366}
367#endif
368