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David Howellsacaebfd2007-05-10 22:51:50 -07001/* 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 */
21static 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 */
41static 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 */
53static 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
David Howells48440e82007-08-30 17:21:19 +010073 sb->s_flags = flags;
74
David Howellsacaebfd2007-05-10 22:51:50 -070075 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;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -080084 simple_set_mnt(mnt, sb);
85
86 return 0;
David Howellsacaebfd2007-05-10 22:51:50 -070087
88 /* new mountpoint for an already mounted superblock */
89already_mounted:
90 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
91 mtd->index, mtd->name);
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -080092 simple_set_mnt(mnt, sb);
93 ret = 0;
David Howellsacaebfd2007-05-10 22:51:50 -070094 goto out_put;
95
96out_error:
97 ret = PTR_ERR(sb);
98out_put:
99 put_mtd_device(mtd);
100 return ret;
101}
102
103/*
104 * get a superblock on an MTD-backed filesystem by MTD device number
105 */
106static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
107 const char *dev_name, void *data, int mtdnr,
108 int (*fill_super)(struct super_block *, void *, int),
109 struct vfsmount *mnt)
110{
111 struct mtd_info *mtd;
112
113 mtd = get_mtd_device(NULL, mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100114 if (IS_ERR(mtd)) {
David Howellsacaebfd2007-05-10 22:51:50 -0700115 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100116 return PTR_ERR(mtd);
David Howellsacaebfd2007-05-10 22:51:50 -0700117 }
118
119 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
120 mnt);
121}
122
123/*
124 * set up an MTD-based superblock
125 */
126int get_sb_mtd(struct file_system_type *fs_type, int flags,
127 const char *dev_name, void *data,
128 int (*fill_super)(struct super_block *, void *, int),
129 struct vfsmount *mnt)
130{
David Woodhousef1136d02008-08-02 00:01:21 +0100131#ifdef CONFIG_BLOCK
Al Virod5686b42008-08-01 05:00:11 -0400132 struct block_device *bdev;
David Woodhousef1136d02008-08-02 00:01:21 +0100133 int ret, major;
134#endif
135 int mtdnr;
David Howellsacaebfd2007-05-10 22:51:50 -0700136
137 if (!dev_name)
138 return -EINVAL;
139
140 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
141
142 /* the preferred way of mounting in future; especially when
143 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
144 * by name, so that we don't require block device support to be present
145 * in the kernel. */
146 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
147 if (dev_name[3] == ':') {
148 struct mtd_info *mtd;
149
150 /* mount by MTD device name */
151 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
152 dev_name + 4);
153
154 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
155 mtd = get_mtd_device(NULL, mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100156 if (!IS_ERR(mtd)) {
David Howellsacaebfd2007-05-10 22:51:50 -0700157 if (!strcmp(mtd->name, dev_name + 4))
158 return get_sb_mtd_aux(
159 fs_type, flags,
160 dev_name, data, mtd,
161 fill_super, mnt);
162
163 put_mtd_device(mtd);
164 }
165 }
166
167 printk(KERN_NOTICE "MTD:"
168 " MTD device with name \"%s\" not found.\n",
169 dev_name + 4);
170
171 } else if (isdigit(dev_name[3])) {
172 /* mount by MTD device number name */
173 char *endptr;
174
175 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
176 if (!*endptr) {
177 /* It was a valid number */
178 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
179 mtdnr);
180 return get_sb_mtd_nr(fs_type, flags,
181 dev_name, data,
182 mtdnr, fill_super, mnt);
183 }
184 }
185 }
186
David Woodhousef1136d02008-08-02 00:01:21 +0100187#ifdef CONFIG_BLOCK
David Howellsacaebfd2007-05-10 22:51:50 -0700188 /* try the old way - the hack where we allowed users to mount
189 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
190 */
Al Virod5686b42008-08-01 05:00:11 -0400191 bdev = lookup_bdev(dev_name);
192 if (IS_ERR(bdev)) {
193 ret = PTR_ERR(bdev);
194 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
David Howellsacaebfd2007-05-10 22:51:50 -0700195 return ret;
Al Virod5686b42008-08-01 05:00:11 -0400196 }
197 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
David Howellsacaebfd2007-05-10 22:51:50 -0700198
199 ret = -EINVAL;
David Howellsacaebfd2007-05-10 22:51:50 -0700200
David Woodhousef1136d02008-08-02 00:01:21 +0100201 major = MAJOR(bdev->bd_dev);
Al Virod5686b42008-08-01 05:00:11 -0400202 mtdnr = MINOR(bdev->bd_dev);
203 bdput(bdev);
David Howellsacaebfd2007-05-10 22:51:50 -0700204
David Woodhousef1136d02008-08-02 00:01:21 +0100205 if (major != MTD_BLOCK_MAJOR)
206 goto not_an_MTD_device;
207
David Howellsacaebfd2007-05-10 22:51:50 -0700208 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
209 mnt);
210
211not_an_MTD_device:
David Woodhousef1136d02008-08-02 00:01:21 +0100212#endif /* CONFIG_BLOCK */
213
David Howellsacaebfd2007-05-10 22:51:50 -0700214 if (!(flags & MS_SILENT))
215 printk(KERN_NOTICE
216 "MTD: Attempt to mount non-MTD device \"%s\"\n",
217 dev_name);
David Woodhousef1136d02008-08-02 00:01:21 +0100218 return -EINVAL;
David Howellsacaebfd2007-05-10 22:51:50 -0700219}
220
221EXPORT_SYMBOL_GPL(get_sb_mtd);
222
223/*
224 * destroy an MTD-based superblock
225 */
226void kill_mtd_super(struct super_block *sb)
227{
228 generic_shutdown_super(sb);
229 put_mtd_device(sb->s_mtd);
230 sb->s_mtd = NULL;
231}
232
233EXPORT_SYMBOL_GPL(kill_mtd_super);