1 /* MTD-based superblock management
2 *
3 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
4 * Written by: David Howells <dhowells@redhat.com>
5 * David Woodhouse <dwmw2@infradead.org>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13 #include <linux/mtd/super.h>
14 #include <linux/namei.h>
15 #include <linux/ctype.h>
16
17 /*
18 * compare superblocks to see if they're equivalent
19 * - they are if the underlying MTD device is the same
20 */
21 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
22 {
23 struct mtd_info *mtd = _mtd;
24
25 if (sb->s_mtd == mtd) {
26 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
27 mtd->index, mtd->name);
28 return 1;
29 }
30
31 DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
32 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
33 return 0;
34 }
35
36 /*
37 * mark the superblock by the MTD device it is using
38 * - set the device number to be the correct MTD block device for pesuperstence
39 * of NFS exports
40 */
41 static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
42 {
43 struct mtd_info *mtd = _mtd;
44
45 sb->s_mtd = mtd;
46 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
47 return 0;
48 }
49
50 /*
51 * get a superblock on an MTD-backed filesystem
52 */
53 static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
54 const char *dev_name, void *data,
55 struct mtd_info *mtd,
56 int (*fill_super)(struct super_block *, void *, int),
57 struct vfsmount *mnt)
58 {
59 struct super_block *sb;
60 int ret;
61
62 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
63 if (IS_ERR(sb))
64 goto out_error;
65
66 if (sb->s_root)
67 goto already_mounted;
68
69 /* fresh new superblock */
70 DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
71 mtd->index, mtd->name);
72
73 sb->s_flags = flags;
74
75 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
76 if (ret < 0) {
77 up_write(&sb->s_umount);
78 deactivate_super(sb);
79 return ret;
80 }
81
82 /* go */
83 sb->s_flags |= MS_ACTIVE;
84 return simple_set_mnt(mnt, sb);
85
86 /* new mountpoint for an already mounted superblock */
87 already_mounted:
88 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
89 mtd->index, mtd->name);
90 ret = simple_set_mnt(mnt, sb);
91 goto out_put;
92
93 out_error:
94 ret = PTR_ERR(sb);
95 out_put:
96 put_mtd_device(mtd);
97 return ret;
98 }
99
100 /*
101 * get a superblock on an MTD-backed filesystem by MTD device number
102 */
103 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
104 const char *dev_name, void *data, int mtdnr,
105 int (*fill_super)(struct super_block *, void *, int),
106 struct vfsmount *mnt)
107 {
108 struct mtd_info *mtd;
109
110 mtd = get_mtd_device(NULL, mtdnr);
111 if (IS_ERR(mtd)) {
112 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
113 return PTR_ERR(mtd);
114 }
115
116 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
117 mnt);
118 }
119
120 /*
121 * set up an MTD-based superblock
122 */
123 int get_sb_mtd(struct file_system_type *fs_type, int flags,
124 const char *dev_name, void *data,
125 int (*fill_super)(struct super_block *, void *, int),
126 struct vfsmount *mnt)
127 {
128 struct nameidata nd;
129 int mtdnr, ret;
130
131 if (!dev_name)
132 return -EINVAL;
133
134 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
135
136 /* the preferred way of mounting in future; especially when
137 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
138 * by name, so that we don't require block device support to be present
139 * in the kernel. */
140 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
141 if (dev_name[3] == ':') {
142 struct mtd_info *mtd;
143
144 /* mount by MTD device name */
145 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
146 dev_name + 4);
147
148 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
149 mtd = get_mtd_device(NULL, mtdnr);
150 if (!IS_ERR(mtd)) {
151 if (!strcmp(mtd->name, dev_name + 4))
152 return get_sb_mtd_aux(
153 fs_type, flags,
154 dev_name, data, mtd,
155 fill_super, mnt);
156
157 put_mtd_device(mtd);
158 }
159 }
160
161 printk(KERN_NOTICE "MTD:"
162 " MTD device with name \"%s\" not found.\n",
163 dev_name + 4);
164
165 } else if (isdigit(dev_name[3])) {
166 /* mount by MTD device number name */
167 char *endptr;
168
169 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
170 if (!*endptr) {
171 /* It was a valid number */
172 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
173 mtdnr);
174 return get_sb_mtd_nr(fs_type, flags,
175 dev_name, data,
176 mtdnr, fill_super, mnt);
177 }
178 }
179 }
180
181 /* try the old way - the hack where we allowed users to mount
182 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
183 */
184 ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
185
186 DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n",
187 ret, nd.path.dentry ? nd.path.dentry->d_inode : NULL);
188
189 if (ret)
190 return ret;
191
192 ret = -EINVAL;
193
194 if (!S_ISBLK(nd.path.dentry->d_inode->i_mode))
195 goto out;
196
197 if (nd.path.mnt->mnt_flags & MNT_NODEV) {
198 ret = -EACCES;
199 goto out;
200 }
201
202 if (imajor(nd.path.dentry->d_inode) != MTD_BLOCK_MAJOR)
203 goto not_an_MTD_device;
204
205 mtdnr = iminor(nd.path.dentry->d_inode);
206 path_put(&nd.path);
207
208 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
209 mnt);
210
211 not_an_MTD_device:
212 if (!(flags & MS_SILENT))
213 printk(KERN_NOTICE
214 "MTD: Attempt to mount non-MTD device \"%s\"\n",
215 dev_name);
216 out:
217 path_put(&nd.path);
218 return ret;
219
220 }
221
222 EXPORT_SYMBOL_GPL(get_sb_mtd);
223
224 /*
225 * destroy an MTD-based superblock
226 */
227 void kill_mtd_super(struct super_block *sb)
228 {
229 generic_shutdown_super(sb);
230 put_mtd_device(sb->s_mtd);
231 sb->s_mtd = NULL;
232 }
233
234 EXPORT_SYMBOL_GPL(kill_mtd_super);
235
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