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1/* MTD-based superblock management
2 *
3 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
4 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
5 *
6 * Written by: David Howells <dhowells@redhat.com>
7 * David Woodhouse <dwmw2@infradead.org>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 */
14
15#include <linux/mtd/super.h>
16#include <linux/namei.h>
17#include <linux/export.h>
18#include <linux/ctype.h>
19#include <linux/slab.h>
20#include <linux/major.h>
21
22/*
23 * compare superblocks to see if they're equivalent
24 * - they are if the underlying MTD device is the same
25 */
26static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
27{
28 struct mtd_info *mtd = _mtd;
29
30 if (sb->s_mtd == mtd) {
31 pr_debug("MTDSB: Match on device %d (\"%s\")\n",
32 mtd->index, mtd->name);
33 return 1;
34 }
35
36 pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
37 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
38 return 0;
39}
40
41/*
42 * mark the superblock by the MTD device it is using
43 * - set the device number to be the correct MTD block device for pesuperstence
44 * of NFS exports
45 */
46static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
47{
48 struct mtd_info *mtd = _mtd;
49
50 sb->s_mtd = mtd;
51 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
52 sb->s_bdi = mtd->backing_dev_info;
53 return 0;
54}
55
56/*
57 * get a superblock on an MTD-backed filesystem
58 */
59static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
60 const char *dev_name, void *data,
61 struct mtd_info *mtd,
62 int (*fill_super)(struct super_block *, void *, int))
63{
64 struct super_block *sb;
65 int ret;
66
67 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
68 if (IS_ERR(sb))
69 goto out_error;
70
71 if (sb->s_root)
72 goto already_mounted;
73
74 /* fresh new superblock */
75 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
76 mtd->index, mtd->name);
77
78 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
79 if (ret < 0) {
80 deactivate_locked_super(sb);
81 return ERR_PTR(ret);
82 }
83
84 /* go */
85 sb->s_flags |= MS_ACTIVE;
86 return dget(sb->s_root);
87
88 /* new mountpoint for an already mounted superblock */
89already_mounted:
90 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
91 mtd->index, mtd->name);
92 put_mtd_device(mtd);
93 return dget(sb->s_root);
94
95out_error:
96 put_mtd_device(mtd);
97 return ERR_CAST(sb);
98}
99
100/*
101 * get a superblock on an MTD-backed filesystem by MTD device number
102 */
103static struct dentry *mount_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{
107 struct mtd_info *mtd;
108
109 mtd = get_mtd_device(NULL, mtdnr);
110 if (IS_ERR(mtd)) {
111 pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
112 return ERR_CAST(mtd);
113 }
114
115 return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
116}
117
118/*
119 * set up an MTD-based superblock
120 */
121struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
122 const char *dev_name, void *data,
123 int (*fill_super)(struct super_block *, void *, int))
124{
125#ifdef CONFIG_BLOCK
126 struct block_device *bdev;
127 int ret, major;
128#endif
129 int mtdnr;
130
131 if (!dev_name)
132 return ERR_PTR(-EINVAL);
133
134 pr_debug("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 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
146 dev_name + 4);
147
148 mtd = get_mtd_device_nm(dev_name + 4);
149 if (!IS_ERR(mtd))
150 return mount_mtd_aux(
151 fs_type, flags,
152 dev_name, data, mtd,
153 fill_super);
154
155 printk(KERN_NOTICE "MTD:"
156 " MTD device with name \"%s\" not found.\n",
157 dev_name + 4);
158
159 } else if (isdigit(dev_name[3])) {
160 /* mount by MTD device number name */
161 char *endptr;
162
163 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
164 if (!*endptr) {
165 /* It was a valid number */
166 pr_debug("MTDSB: mtd%%d, mtdnr %d\n",
167 mtdnr);
168 return mount_mtd_nr(fs_type, flags,
169 dev_name, data,
170 mtdnr, fill_super);
171 }
172 }
173 }
174
175#ifdef CONFIG_BLOCK
176 /* try the old way - the hack where we allowed users to mount
177 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
178 */
179 bdev = lookup_bdev(dev_name);
180 if (IS_ERR(bdev)) {
181 ret = PTR_ERR(bdev);
182 pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
183 return ERR_PTR(ret);
184 }
185 pr_debug("MTDSB: lookup_bdev() returned 0\n");
186
187 ret = -EINVAL;
188
189 major = MAJOR(bdev->bd_dev);
190 mtdnr = MINOR(bdev->bd_dev);
191 bdput(bdev);
192
193 if (major != MTD_BLOCK_MAJOR)
194 goto not_an_MTD_device;
195
196 return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
197
198not_an_MTD_device:
199#endif /* CONFIG_BLOCK */
200
201 if (!(flags & MS_SILENT))
202 printk(KERN_NOTICE
203 "MTD: Attempt to mount non-MTD device \"%s\"\n",
204 dev_name);
205 return ERR_PTR(-EINVAL);
206}
207
208EXPORT_SYMBOL_GPL(mount_mtd);
209
210/*
211 * destroy an MTD-based superblock
212 */
213void kill_mtd_super(struct super_block *sb)
214{
215 generic_shutdown_super(sb);
216 put_mtd_device(sb->s_mtd);
217 sb->s_mtd = NULL;
218}
219
220EXPORT_SYMBOL_GPL(kill_mtd_super);