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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 #include <linux/slab.h>
17
18 /*
19 * compare superblocks to see if they're equivalent
20 * - they are if the underlying MTD device is the same
21 */
22 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
23 {
24 struct mtd_info *mtd = _mtd;
25
26 if (sb->s_mtd == mtd) {
27 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
28 mtd->index, mtd->name);
29 return 1;
30 }
31
32 DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
33 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
34 return 0;
35 }
36
37 /*
38 * mark the superblock by the MTD device it is using
39 * - set the device number to be the correct MTD block device for pesuperstence
40 * of NFS exports
41 */
42 static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
43 {
44 struct mtd_info *mtd = _mtd;
45
46 sb->s_mtd = mtd;
47 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
48 sb->s_bdi = mtd->backing_dev_info;
49 return 0;
50 }
51
52 /*
53 * get a superblock on an MTD-backed filesystem
54 */
55 static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
56 const char *dev_name, void *data,
57 struct mtd_info *mtd,
58 int (*fill_super)(struct super_block *, void *, int),
59 struct vfsmount *mnt)
60 {
61 struct super_block *sb;
62 int ret;
63
64 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
65 if (IS_ERR(sb))
66 goto out_error;
67
68 if (sb->s_root)
69 goto already_mounted;
70
71 /* fresh new superblock */
72 DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
73 mtd->index, mtd->name);
74
75 sb->s_flags = flags;
76
77 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
78 if (ret < 0) {
79 deactivate_locked_super(sb);
80 return ret;
81 }
82
83 /* go */
84 sb->s_flags |= MS_ACTIVE;
85 simple_set_mnt(mnt, sb);
86
87 return 0;
88
89 /* new mountpoint for an already mounted superblock */
90 already_mounted:
91 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
92 mtd->index, mtd->name);
93 simple_set_mnt(mnt, sb);
94 ret = 0;
95 goto out_put;
96
97 out_error:
98 ret = PTR_ERR(sb);
99 out_put:
100 put_mtd_device(mtd);
101 return ret;
102 }
103
104 /*
105 * get a superblock on an MTD-backed filesystem by MTD device number
106 */
107 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
108 const char *dev_name, void *data, int mtdnr,
109 int (*fill_super)(struct super_block *, void *, int),
110 struct vfsmount *mnt)
111 {
112 struct mtd_info *mtd;
113
114 mtd = get_mtd_device(NULL, mtdnr);
115 if (IS_ERR(mtd)) {
116 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
117 return PTR_ERR(mtd);
118 }
119
120 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
121 mnt);
122 }
123
124 /*
125 * set up an MTD-based superblock
126 */
127 int get_sb_mtd(struct file_system_type *fs_type, int flags,
128 const char *dev_name, void *data,
129 int (*fill_super)(struct super_block *, void *, int),
130 struct vfsmount *mnt)
131 {
132 #ifdef CONFIG_BLOCK
133 struct block_device *bdev;
134 int ret, major;
135 #endif
136 int mtdnr;
137
138 if (!dev_name)
139 return -EINVAL;
140
141 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
142
143 /* the preferred way of mounting in future; especially when
144 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
145 * by name, so that we don't require block device support to be present
146 * in the kernel. */
147 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
148 if (dev_name[3] == ':') {
149 struct mtd_info *mtd;
150
151 /* mount by MTD device name */
152 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
153 dev_name + 4);
154
155 mtd = get_mtd_device_nm(dev_name + 4);
156 if (!IS_ERR(mtd))
157 return get_sb_mtd_aux(
158 fs_type, flags,
159 dev_name, data, mtd,
160 fill_super, mnt);
161
162 printk(KERN_NOTICE "MTD:"
163 " MTD device with name \"%s\" not found.\n",
164 dev_name + 4);
165
166 } else if (isdigit(dev_name[3])) {
167 /* mount by MTD device number name */
168 char *endptr;
169
170 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
171 if (!*endptr) {
172 /* It was a valid number */
173 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
174 mtdnr);
175 return get_sb_mtd_nr(fs_type, flags,
176 dev_name, data,
177 mtdnr, fill_super, mnt);
178 }
179 }
180 }
181
182 #ifdef CONFIG_BLOCK
183 /* try the old way - the hack where we allowed users to mount
184 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
185 */
186 bdev = lookup_bdev(dev_name);
187 if (IS_ERR(bdev)) {
188 ret = PTR_ERR(bdev);
189 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
190 return ret;
191 }
192 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
193
194 ret = -EINVAL;
195
196 major = MAJOR(bdev->bd_dev);
197 mtdnr = MINOR(bdev->bd_dev);
198 bdput(bdev);
199
200 if (major != MTD_BLOCK_MAJOR)
201 goto not_an_MTD_device;
202
203 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
204 mnt);
205
206 not_an_MTD_device:
207 #endif /* CONFIG_BLOCK */
208
209 if (!(flags & MS_SILENT))
210 printk(KERN_NOTICE
211 "MTD: Attempt to mount non-MTD device \"%s\"\n",
212 dev_name);
213 return -EINVAL;
214 }
215
216 EXPORT_SYMBOL_GPL(get_sb_mtd);
217
218 /*
219 * destroy an MTD-based superblock
220 */
221 void kill_mtd_super(struct super_block *sb)
222 {
223 generic_shutdown_super(sb);
224 put_mtd_device(sb->s_mtd);
225 sb->s_mtd = NULL;
226 }
227
228 EXPORT_SYMBOL_GPL(kill_mtd_super);