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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) {
Al Viro6f5bbff2009-05-06 01:34:22 -040077 deactivate_locked_super(sb);
David Howellsacaebfd2007-05-10 22:51:50 -070078 return ret;
79 }
80
81 /* go */
82 sb->s_flags |= MS_ACTIVE;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -080083 simple_set_mnt(mnt, sb);
84
85 return 0;
David Howellsacaebfd2007-05-10 22:51:50 -070086
87 /* new mountpoint for an already mounted superblock */
88already_mounted:
89 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
90 mtd->index, mtd->name);
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -080091 simple_set_mnt(mnt, sb);
92 ret = 0;
David Howellsacaebfd2007-05-10 22:51:50 -070093 goto out_put;
94
95out_error:
96 ret = PTR_ERR(sb);
97out_put:
98 put_mtd_device(mtd);
99 return ret;
100}
101
102/*
103 * get a superblock on an MTD-backed filesystem by MTD device number
104 */
105static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
106 const char *dev_name, void *data, int mtdnr,
107 int (*fill_super)(struct super_block *, void *, int),
108 struct vfsmount *mnt)
109{
110 struct mtd_info *mtd;
111
112 mtd = get_mtd_device(NULL, mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100113 if (IS_ERR(mtd)) {
David Howellsacaebfd2007-05-10 22:51:50 -0700114 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100115 return PTR_ERR(mtd);
David Howellsacaebfd2007-05-10 22:51:50 -0700116 }
117
118 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
119 mnt);
120}
121
122/*
123 * set up an MTD-based superblock
124 */
125int get_sb_mtd(struct file_system_type *fs_type, int flags,
126 const char *dev_name, void *data,
127 int (*fill_super)(struct super_block *, void *, int),
128 struct vfsmount *mnt)
129{
David Woodhousef1136d02008-08-02 00:01:21 +0100130#ifdef CONFIG_BLOCK
Al Virod5686b42008-08-01 05:00:11 -0400131 struct block_device *bdev;
David Woodhousef1136d02008-08-02 00:01:21 +0100132 int ret, major;
133#endif
134 int mtdnr;
David Howellsacaebfd2007-05-10 22:51:50 -0700135
136 if (!dev_name)
137 return -EINVAL;
138
139 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
140
141 /* the preferred way of mounting in future; especially when
142 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
143 * by name, so that we don't require block device support to be present
144 * in the kernel. */
145 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
146 if (dev_name[3] == ':') {
147 struct mtd_info *mtd;
148
149 /* mount by MTD device name */
150 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
151 dev_name + 4);
152
153 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
154 mtd = get_mtd_device(NULL, mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100155 if (!IS_ERR(mtd)) {
David Howellsacaebfd2007-05-10 22:51:50 -0700156 if (!strcmp(mtd->name, dev_name + 4))
157 return get_sb_mtd_aux(
158 fs_type, flags,
159 dev_name, data, mtd,
160 fill_super, mnt);
161
162 put_mtd_device(mtd);
163 }
164 }
165
166 printk(KERN_NOTICE "MTD:"
167 " MTD device with name \"%s\" not found.\n",
168 dev_name + 4);
169
170 } else if (isdigit(dev_name[3])) {
171 /* mount by MTD device number name */
172 char *endptr;
173
174 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
175 if (!*endptr) {
176 /* It was a valid number */
177 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
178 mtdnr);
179 return get_sb_mtd_nr(fs_type, flags,
180 dev_name, data,
181 mtdnr, fill_super, mnt);
182 }
183 }
184 }
185
David Woodhousef1136d02008-08-02 00:01:21 +0100186#ifdef CONFIG_BLOCK
David Howellsacaebfd2007-05-10 22:51:50 -0700187 /* try the old way - the hack where we allowed users to mount
188 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
189 */
Al Virod5686b42008-08-01 05:00:11 -0400190 bdev = lookup_bdev(dev_name);
191 if (IS_ERR(bdev)) {
192 ret = PTR_ERR(bdev);
193 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
David Howellsacaebfd2007-05-10 22:51:50 -0700194 return ret;
Al Virod5686b42008-08-01 05:00:11 -0400195 }
196 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
David Howellsacaebfd2007-05-10 22:51:50 -0700197
198 ret = -EINVAL;
David Howellsacaebfd2007-05-10 22:51:50 -0700199
David Woodhousef1136d02008-08-02 00:01:21 +0100200 major = MAJOR(bdev->bd_dev);
Al Virod5686b42008-08-01 05:00:11 -0400201 mtdnr = MINOR(bdev->bd_dev);
202 bdput(bdev);
David Howellsacaebfd2007-05-10 22:51:50 -0700203
David Woodhousef1136d02008-08-02 00:01:21 +0100204 if (major != MTD_BLOCK_MAJOR)
205 goto not_an_MTD_device;
206
David Howellsacaebfd2007-05-10 22:51:50 -0700207 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
208 mnt);
209
210not_an_MTD_device:
David Woodhousef1136d02008-08-02 00:01:21 +0100211#endif /* CONFIG_BLOCK */
212
David Howellsacaebfd2007-05-10 22:51:50 -0700213 if (!(flags & MS_SILENT))
214 printk(KERN_NOTICE
215 "MTD: Attempt to mount non-MTD device \"%s\"\n",
216 dev_name);
David Woodhousef1136d02008-08-02 00:01:21 +0100217 return -EINVAL;
David Howellsacaebfd2007-05-10 22:51:50 -0700218}
219
220EXPORT_SYMBOL_GPL(get_sb_mtd);
221
222/*
223 * destroy an MTD-based superblock
224 */
225void kill_mtd_super(struct super_block *sb)
226{
227 generic_shutdown_super(sb);
228 put_mtd_device(sb->s_mtd);
229 sb->s_mtd = NULL;
230}
231
232EXPORT_SYMBOL_GPL(kill_mtd_super);