1 /* $NetBSD: disksubr.c,v 1.18 2019/04/03 22:10:50 christos Exp $ */
2
3 /*
4 * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
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 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)ufs_disksubr.c 7.16 (Berkeley) 5/4/91
32 */
33
34 #include <sys/cdefs.h>
35 __KERNEL_RCSID(0, "$NetBSD: disksubr.c,v 1.18 2019/04/03 22:10:50 christos Exp $");
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/buf.h>
40 #include <sys/disklabel.h>
41 #include <sys/disk.h>
42 #include <sys/syslog.h>
43
44 /*
45 * Attempt to read a disk label from a device
46 * using the indicated strategy routine.
47 * The label must be partly set up before this:
48 * secpercyl, secsize and anything required for a block i/o read
49 * operation in the driver's strategy/start routines
50 * must be filled in before calling us.
51 *
52 * If dos partition table requested, attempt to load it and
53 * find disklabel inside a DOS partition. Also, if bad block
54 * table needed, attempt to extract it as well. Return buffer
55 * for use in signalling errors if requested.
56 *
57 * Returns null on success and an error string on failure.
58 */
59 const char *
readdisklabel(dev_t dev,void (* strat)(struct buf *),struct disklabel * lp,struct cpu_disklabel * osdep)60 readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
61 struct cpu_disklabel *osdep)
62 {
63 struct buf *bp;
64 struct disklabel *dlp;
65 struct dkbad *bdp;
66 const char *msg = NULL;
67 int i;
68
69 /* minimal requirements for archtypal disk label */
70 if (lp->d_secsize == 0)
71 lp->d_secsize = DEV_BSIZE;
72 if (lp->d_secperunit == 0)
73 lp->d_secperunit = 0x1fffffff;
74 lp->d_npartitions = RAW_PART + 1;
75 if (lp->d_partitions[RAW_PART].p_size == 0)
76 lp->d_partitions[RAW_PART].p_size = lp->d_secperunit;
77 lp->d_partitions[RAW_PART].p_offset = 0;
78
79 /* get a buffer and initialize it */
80 bp = geteblk((int)lp->d_secsize);
81
82 /* next, dig out disk label */
83 bp->b_dev = dev;
84 bp->b_blkno = LABELSECTOR;
85 bp->b_cylinder = 0;
86 bp->b_bcount = lp->d_secsize;
87 bp->b_flags |= B_READ;
88 (*strat)(bp);
89
90 /* if successful, locate disk label within block and validate */
91 if (biowait(bp)) {
92 msg = "disk label I/O error";
93 goto done;
94 }
95
96 for (dlp = (struct disklabel *)bp->b_data;
97 dlp <= (struct disklabel *)((char *)bp->b_data + lp->d_secsize -
98 sizeof(*dlp));
99 dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
100 if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
101 if (msg == NULL)
102 msg = "no disk label";
103 } else if (dlp->d_npartitions > MAXPARTITIONS ||
104 dkcksum(dlp) != 0)
105 msg = "disk label corrupted";
106 else {
107 *lp = *dlp;
108 msg = NULL;
109 break;
110 }
111 }
112
113 if (msg)
114 goto done;
115
116 /* obtain bad sector table if requested and present */
117 if (osdep && (lp->d_flags & D_BADSECT)) {
118 struct dkbad *db;
119
120 bdp = &osdep->bad;
121 i = 0;
122 do {
123 /* read a bad sector table */
124 bp->b_oflags &= ~BO_DONE;
125 bp->b_flags |= B_READ;
126 bp->b_blkno = lp->d_secperunit - lp->d_nsectors + i;
127 if (lp->d_secsize > DEV_BSIZE)
128 bp->b_blkno *= lp->d_secsize / DEV_BSIZE;
129 else
130 bp->b_blkno /= DEV_BSIZE / lp->d_secsize;
131 bp->b_bcount = lp->d_secsize;
132 bp->b_cylinder = lp->d_ncylinders - 1;
133 (*strat)(bp);
134
135 /* if successful, validate, otherwise try another */
136 if (biowait(bp)) {
137 msg = "bad sector table I/O error";
138 } else {
139 db = (struct dkbad *)(bp->b_data);
140 #define DKBAD_MAGIC 0x4321
141 if (db->bt_mbz == 0
142 && db->bt_flag == DKBAD_MAGIC) {
143 msg = NULL;
144 *bdp = *db;
145 break;
146 } else
147 msg = "bad sector table corrupted";
148 }
149 } while (bp->b_error != 0 && (i += 2) < 10 &&
150 i < lp->d_nsectors);
151 }
152
153 done:
154 brelse(bp, BC_INVAL);
155 return (msg);
156 }
157
158
159 /*
160 * Write disk label back to device after modification.
161 */
162 int
writedisklabel(dev_t dev,void (* strat)(struct buf *),struct disklabel * lp,struct cpu_disklabel * osdep)163 writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
164 struct cpu_disklabel *osdep)
165 {
166 struct buf *bp;
167 struct disklabel *dlp;
168 int error;
169
170 #ifdef maybe
171 /* disklabel in appropriate location? */
172 if (lp->d_partitions[2].p_offset != 0
173 && lp->d_partitions[2].p_offset != dospartoff) {
174 error = EXDEV;
175 goto done;
176 }
177 #endif
178
179 /* get a buffer and initialize it */
180 bp = geteblk((int)lp->d_secsize);
181 bp->b_dev = dev;
182 bp->b_blkno = LABELSECTOR;
183 bp->b_cylinder = 0;
184 bp->b_bcount = lp->d_secsize;
185 bp->b_flags |= B_READ;
186 (*strat)(bp);
187
188 /* if successful, locate disk label within block and validate */
189 if ((error = biowait(bp)) != 0)
190 goto done;
191 for (dlp = (struct disklabel *)bp->b_data;
192 dlp <= (struct disklabel *)((char *)bp->b_data + lp->d_secsize -
193 sizeof(*dlp));
194 dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
195 if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
196 dkcksum(dlp) == 0) {
197 *dlp = *lp;
198 bp->b_cflags = BC_BUSY;
199 bp->b_flags = B_WRITE;
200 CLR(bp->b_oflags, BO_DONE);
201 (*strat)(bp);
202 error = biowait(bp);
203 goto done;
204 }
205 }
206 error = ESRCH;
207
208 done:
209 brelse(bp, 0);
210 return (error);
211 }
212