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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>
Paul Gortmakerf3bcc012011-07-10 12:43:28 -040017#include <linux/export.h>
David Howellsacaebfd2007-05-10 22:51:50 -070018#include <linux/ctype.h>
Jörn Engel6de94002010-04-22 14:11:43 +020019#include <linux/slab.h>
Ezequiel Garciaf83c3832013-10-13 18:05:23 -030020#include <linux/major.h>
Jan Karafa060522017-04-12 12:24:37 +020021#include <linux/backing-dev.h>
David Howellsacaebfd2007-05-10 22:51:50 -070022
23/*
24 * compare superblocks to see if they're equivalent
25 * - they are if the underlying MTD device is the same
26 */
27static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
28{
29 struct mtd_info *mtd = _mtd;
30
31 if (sb->s_mtd == mtd) {
Brian Norris289c0522011-07-19 10:06:09 -070032 pr_debug("MTDSB: Match on device %d (\"%s\")\n",
David Howellsacaebfd2007-05-10 22:51:50 -070033 mtd->index, mtd->name);
34 return 1;
35 }
36
Brian Norris289c0522011-07-19 10:06:09 -070037 pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
David Howellsacaebfd2007-05-10 22:51:50 -070038 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
39 return 0;
40}
41
Jan Karafa060522017-04-12 12:24:37 +020042extern struct backing_dev_info *mtd_bdi;
43
David Howellsacaebfd2007-05-10 22:51:50 -070044/*
45 * mark the superblock by the MTD device it is using
46 * - set the device number to be the correct MTD block device for pesuperstence
47 * of NFS exports
48 */
49static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
50{
51 struct mtd_info *mtd = _mtd;
52
53 sb->s_mtd = mtd;
54 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
Jan Karafa060522017-04-12 12:24:37 +020055 sb->s_bdi = bdi_get(mtd_bdi);
56 sb->s_iflags |= SB_I_DYNBDI;
57
David Howellsacaebfd2007-05-10 22:51:50 -070058 return 0;
59}
60
61/*
62 * get a superblock on an MTD-backed filesystem
63 */
Al Viro848b83a2010-07-25 00:56:46 +040064static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
David Howellsacaebfd2007-05-10 22:51:50 -070065 const char *dev_name, void *data,
66 struct mtd_info *mtd,
Al Viro848b83a2010-07-25 00:56:46 +040067 int (*fill_super)(struct super_block *, void *, int))
David Howellsacaebfd2007-05-10 22:51:50 -070068{
69 struct super_block *sb;
70 int ret;
71
David Howells9249e172012-06-25 12:55:37 +010072 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
David Howellsacaebfd2007-05-10 22:51:50 -070073 if (IS_ERR(sb))
74 goto out_error;
75
76 if (sb->s_root)
77 goto already_mounted;
78
79 /* fresh new superblock */
Brian Norris289c0522011-07-19 10:06:09 -070080 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
David Howellsacaebfd2007-05-10 22:51:50 -070081 mtd->index, mtd->name);
82
83 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
84 if (ret < 0) {
Al Viro6f5bbff2009-05-06 01:34:22 -040085 deactivate_locked_super(sb);
Al Viro848b83a2010-07-25 00:56:46 +040086 return ERR_PTR(ret);
David Howellsacaebfd2007-05-10 22:51:50 -070087 }
88
89 /* go */
90 sb->s_flags |= MS_ACTIVE;
Al Viro848b83a2010-07-25 00:56:46 +040091 return dget(sb->s_root);
David Howellsacaebfd2007-05-10 22:51:50 -070092
93 /* new mountpoint for an already mounted superblock */
94already_mounted:
Brian Norris289c0522011-07-19 10:06:09 -070095 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
David Howellsacaebfd2007-05-10 22:51:50 -070096 mtd->index, mtd->name);
Al Viro848b83a2010-07-25 00:56:46 +040097 put_mtd_device(mtd);
98 return dget(sb->s_root);
David Howellsacaebfd2007-05-10 22:51:50 -070099
100out_error:
David Howellsacaebfd2007-05-10 22:51:50 -0700101 put_mtd_device(mtd);
Al Viro848b83a2010-07-25 00:56:46 +0400102 return ERR_CAST(sb);
David Howellsacaebfd2007-05-10 22:51:50 -0700103}
104
105/*
106 * get a superblock on an MTD-backed filesystem by MTD device number
107 */
Al Viro848b83a2010-07-25 00:56:46 +0400108static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
David Howellsacaebfd2007-05-10 22:51:50 -0700109 const char *dev_name, void *data, int mtdnr,
Al Viro848b83a2010-07-25 00:56:46 +0400110 int (*fill_super)(struct super_block *, void *, int))
David Howellsacaebfd2007-05-10 22:51:50 -0700111{
112 struct mtd_info *mtd;
113
114 mtd = get_mtd_device(NULL, mtdnr);
David Woodhouse718ea832007-06-01 19:21:59 +0100115 if (IS_ERR(mtd)) {
Brian Norris289c0522011-07-19 10:06:09 -0700116 pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
Al Viro848b83a2010-07-25 00:56:46 +0400117 return ERR_CAST(mtd);
David Howellsacaebfd2007-05-10 22:51:50 -0700118 }
119
Al Viro848b83a2010-07-25 00:56:46 +0400120 return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700121}
122
123/*
124 * set up an MTD-based superblock
125 */
Al Viro848b83a2010-07-25 00:56:46 +0400126struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
David Howellsacaebfd2007-05-10 22:51:50 -0700127 const char *dev_name, void *data,
Al Viro848b83a2010-07-25 00:56:46 +0400128 int (*fill_super)(struct super_block *, void *, int))
David Howellsacaebfd2007-05-10 22:51:50 -0700129{
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)
Al Viro848b83a2010-07-25 00:56:46 +0400137 return ERR_PTR(-EINVAL);
David Howellsacaebfd2007-05-10 22:51:50 -0700138
Brian Norris289c0522011-07-19 10:06:09 -0700139 pr_debug("MTDSB: dev_name \"%s\"\n", dev_name);
David Howellsacaebfd2007-05-10 22:51:50 -0700140
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 */
Brian Norris289c0522011-07-19 10:06:09 -0700150 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
David Howellsacaebfd2007-05-10 22:51:50 -0700151 dev_name + 4);
152
Ben Hutchings677c2ae2010-01-29 20:57:18 +0000153 mtd = get_mtd_device_nm(dev_name + 4);
154 if (!IS_ERR(mtd))
Al Viro848b83a2010-07-25 00:56:46 +0400155 return mount_mtd_aux(
Ben Hutchings677c2ae2010-01-29 20:57:18 +0000156 fs_type, flags,
157 dev_name, data, mtd,
Al Viro848b83a2010-07-25 00:56:46 +0400158 fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700159
160 printk(KERN_NOTICE "MTD:"
161 " MTD device with name \"%s\" not found.\n",
162 dev_name + 4);
163
164 } else if (isdigit(dev_name[3])) {
165 /* mount by MTD device number name */
166 char *endptr;
167
168 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
169 if (!*endptr) {
170 /* It was a valid number */
Brian Norris289c0522011-07-19 10:06:09 -0700171 pr_debug("MTDSB: mtd%%d, mtdnr %d\n",
David Howellsacaebfd2007-05-10 22:51:50 -0700172 mtdnr);
Al Viro848b83a2010-07-25 00:56:46 +0400173 return mount_mtd_nr(fs_type, flags,
David Howellsacaebfd2007-05-10 22:51:50 -0700174 dev_name, data,
Al Viro848b83a2010-07-25 00:56:46 +0400175 mtdnr, fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700176 }
177 }
178 }
179
David Woodhousef1136d02008-08-02 00:01:21 +0100180#ifdef CONFIG_BLOCK
David Howellsacaebfd2007-05-10 22:51:50 -0700181 /* try the old way - the hack where we allowed users to mount
182 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
183 */
Al Virod5686b42008-08-01 05:00:11 -0400184 bdev = lookup_bdev(dev_name);
185 if (IS_ERR(bdev)) {
186 ret = PTR_ERR(bdev);
Brian Norris289c0522011-07-19 10:06:09 -0700187 pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
Al Viro848b83a2010-07-25 00:56:46 +0400188 return ERR_PTR(ret);
Al Virod5686b42008-08-01 05:00:11 -0400189 }
Brian Norris289c0522011-07-19 10:06:09 -0700190 pr_debug("MTDSB: lookup_bdev() returned 0\n");
David Howellsacaebfd2007-05-10 22:51:50 -0700191
192 ret = -EINVAL;
David Howellsacaebfd2007-05-10 22:51:50 -0700193
David Woodhousef1136d02008-08-02 00:01:21 +0100194 major = MAJOR(bdev->bd_dev);
Al Virod5686b42008-08-01 05:00:11 -0400195 mtdnr = MINOR(bdev->bd_dev);
196 bdput(bdev);
David Howellsacaebfd2007-05-10 22:51:50 -0700197
David Woodhousef1136d02008-08-02 00:01:21 +0100198 if (major != MTD_BLOCK_MAJOR)
199 goto not_an_MTD_device;
200
Al Viro848b83a2010-07-25 00:56:46 +0400201 return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
David Howellsacaebfd2007-05-10 22:51:50 -0700202
203not_an_MTD_device:
David Woodhousef1136d02008-08-02 00:01:21 +0100204#endif /* CONFIG_BLOCK */
205
David Howellsacaebfd2007-05-10 22:51:50 -0700206 if (!(flags & MS_SILENT))
207 printk(KERN_NOTICE
208 "MTD: Attempt to mount non-MTD device \"%s\"\n",
209 dev_name);
Al Viro848b83a2010-07-25 00:56:46 +0400210 return ERR_PTR(-EINVAL);
David Howellsacaebfd2007-05-10 22:51:50 -0700211}
212
Al Viro848b83a2010-07-25 00:56:46 +0400213EXPORT_SYMBOL_GPL(mount_mtd);
David Howellsacaebfd2007-05-10 22:51:50 -0700214
215/*
216 * destroy an MTD-based superblock
217 */
218void kill_mtd_super(struct super_block *sb)
219{
220 generic_shutdown_super(sb);
221 put_mtd_device(sb->s_mtd);
222 sb->s_mtd = NULL;
223}
224
225EXPORT_SYMBOL_GPL(kill_mtd_super);