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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.
David Woodhousea1452a32010-08-08 20:58:20 +01004 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
5 *
David Howellsacaebfd2007-05-10 22:51:50 -07006 * 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/ctype.h>
Jörn Engel6de94002010-04-22 14:11:43 +020018#include <linux/slab.h>
David Howellsacaebfd2007-05-10 22:51:50 -070019
20/*
21 * compare superblocks to see if they're equivalent
22 * - they are if the underlying MTD device is the same
23 */
24static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
25{
26 struct mtd_info *mtd = _mtd;
27
28 if (sb->s_mtd == mtd) {
29 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
30 mtd->index, mtd->name);
31 return 1;
32 }
33
34 DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
35 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
36 return 0;
37}
38
39/*
40 * mark the superblock by the MTD device it is using
41 * - set the device number to be the correct MTD block device for pesuperstence
42 * of NFS exports
43 */
44static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
45{
46 struct mtd_info *mtd = _mtd;
47
48 sb->s_mtd = mtd;
49 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
Jörn Engel6de94002010-04-22 14:11:43 +020050 sb->s_bdi = mtd->backing_dev_info;
David Howellsacaebfd2007-05-10 22:51:50 -070051 return 0;
52}
53
54/*
55 * get a superblock on an MTD-backed filesystem
56 */
Al Viro848b83a2010-07-25 00:56:46 +040057static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
David Howellsacaebfd2007-05-10 22:51:50 -070058 const char *dev_name, void *data,
59 struct mtd_info *mtd,
Al Viro848b83a2010-07-25 00:56:46 +040060 int (*fill_super)(struct super_block *, void *, int))
David Howellsacaebfd2007-05-10 22:51:50 -070061{
62 struct super_block *sb;
63 int ret;
64
65 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
66 if (IS_ERR(sb))
67 goto out_error;
68
69 if (sb->s_root)
70 goto already_mounted;
71
72 /* fresh new superblock */
73 DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
74 mtd->index, mtd->name);
75
David Howells48440e82007-08-30 17:21:19 +010076 sb->s_flags = flags;
77
David Howellsacaebfd2007-05-10 22:51:50 -070078 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
79 if (ret < 0) {
Al Viro6f5bbff2009-05-06 01:34:22 -040080 deactivate_locked_super(sb);
Al Viro848b83a2010-07-25 00:56:46 +040081 return ERR_PTR(ret);
David Howellsacaebfd2007-05-10 22:51:50 -070082 }
83
84 /* go */
85 sb->s_flags |= MS_ACTIVE;
Al Viro848b83a2010-07-25 00:56:46 +040086 return dget(sb->s_root);
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);
Al Viro848b83a2010-07-25 00:56:46 +040092 put_mtd_device(mtd);
93 return dget(sb->s_root);
David Howellsacaebfd2007-05-10 22:51:50 -070094
95out_error:
David Howellsacaebfd2007-05-10 22:51:50 -070096 put_mtd_device(mtd);
Al Viro848b83a2010-07-25 00:56:46 +040097 return ERR_CAST(sb);
David Howellsacaebfd2007-05-10 22:51:50 -070098}
99
100/*
101 * get a superblock on an MTD-backed filesystem by MTD device number
102 */
Al Viro848b83a2010-07-25 00:56:46 +0400103static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
David Howellsacaebfd2007-05-10 22:51:50 -0700104 const char *dev_name, void *data, int mtdnr,
Al Viro848b83a2010-07-25 00:56:46 +0400105 int (*fill_super)(struct super_block *, void *, int))
David Howellsacaebfd2007-05-10 22:51:50 -0700106{
107 struct mtd_info *mtd;
108
109 mtd = get_mtd_device(NULL, mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100110 if (IS_ERR(mtd)) {
David Howellsacaebfd2007-05-10 22:51:50 -0700111 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
Al Viro848b83a2010-07-25 00:56:46 +0400112 return ERR_CAST(mtd);
David Howellsacaebfd2007-05-10 22:51:50 -0700113 }
114
Al Viro848b83a2010-07-25 00:56:46 +0400115 return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700116}
117
118/*
119 * set up an MTD-based superblock
120 */
Al Viro848b83a2010-07-25 00:56:46 +0400121struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
David Howellsacaebfd2007-05-10 22:51:50 -0700122 const char *dev_name, void *data,
Al Viro848b83a2010-07-25 00:56:46 +0400123 int (*fill_super)(struct super_block *, void *, int))
David Howellsacaebfd2007-05-10 22:51:50 -0700124{
David Woodhousef1136d02008-08-02 00:01:21 +0100125#ifdef CONFIG_BLOCK
Al Virod5686b42008-08-01 05:00:11 -0400126 struct block_device *bdev;
David Woodhousef1136d02008-08-02 00:01:21 +0100127 int ret, major;
128#endif
129 int mtdnr;
David Howellsacaebfd2007-05-10 22:51:50 -0700130
131 if (!dev_name)
Al Viro848b83a2010-07-25 00:56:46 +0400132 return ERR_PTR(-EINVAL);
David Howellsacaebfd2007-05-10 22:51:50 -0700133
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
Ben Hutchings677c2ae2010-01-29 20:57:18 +0000148 mtd = get_mtd_device_nm(dev_name + 4);
149 if (!IS_ERR(mtd))
Al Viro848b83a2010-07-25 00:56:46 +0400150 return mount_mtd_aux(
Ben Hutchings677c2ae2010-01-29 20:57:18 +0000151 fs_type, flags,
152 dev_name, data, mtd,
Al Viro848b83a2010-07-25 00:56:46 +0400153 fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700154
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 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
167 mtdnr);
Al Viro848b83a2010-07-25 00:56:46 +0400168 return mount_mtd_nr(fs_type, flags,
David Howellsacaebfd2007-05-10 22:51:50 -0700169 dev_name, data,
Al Viro848b83a2010-07-25 00:56:46 +0400170 mtdnr, fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700171 }
172 }
173 }
174
David Woodhousef1136d02008-08-02 00:01:21 +0100175#ifdef CONFIG_BLOCK
David Howellsacaebfd2007-05-10 22:51:50 -0700176 /* try the old way - the hack where we allowed users to mount
177 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
178 */
Al Virod5686b42008-08-01 05:00:11 -0400179 bdev = lookup_bdev(dev_name);
180 if (IS_ERR(bdev)) {
181 ret = PTR_ERR(bdev);
182 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
Al Viro848b83a2010-07-25 00:56:46 +0400183 return ERR_PTR(ret);
Al Virod5686b42008-08-01 05:00:11 -0400184 }
185 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
David Howellsacaebfd2007-05-10 22:51:50 -0700186
187 ret = -EINVAL;
David Howellsacaebfd2007-05-10 22:51:50 -0700188
David Woodhousef1136d02008-08-02 00:01:21 +0100189 major = MAJOR(bdev->bd_dev);
Al Virod5686b42008-08-01 05:00:11 -0400190 mtdnr = MINOR(bdev->bd_dev);
191 bdput(bdev);
David Howellsacaebfd2007-05-10 22:51:50 -0700192
David Woodhousef1136d02008-08-02 00:01:21 +0100193 if (major != MTD_BLOCK_MAJOR)
194 goto not_an_MTD_device;
195
Al Viro848b83a2010-07-25 00:56:46 +0400196 return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700197
198not_an_MTD_device:
David Woodhousef1136d02008-08-02 00:01:21 +0100199#endif /* CONFIG_BLOCK */
200
David Howellsacaebfd2007-05-10 22:51:50 -0700201 if (!(flags & MS_SILENT))
202 printk(KERN_NOTICE
203 "MTD: Attempt to mount non-MTD device \"%s\"\n",
204 dev_name);
Al Viro848b83a2010-07-25 00:56:46 +0400205 return ERR_PTR(-EINVAL);
David Howellsacaebfd2007-05-10 22:51:50 -0700206}
207
Al Viro848b83a2010-07-25 00:56:46 +0400208EXPORT_SYMBOL_GPL(mount_mtd);
David Howellsacaebfd2007-05-10 22:51:50 -0700209
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);