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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* MTD-based superblock management
3 *
4 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
5 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
6 *
7 * Written by: David Howells <dhowells@redhat.com>
8 * David Woodhouse <dwmw2@infradead.org>
9 */
10
11#include <linux/mtd/super.h>
12#include <linux/namei.h>
13#include <linux/export.h>
14#include <linux/ctype.h>
15#include <linux/slab.h>
16#include <linux/major.h>
17#include <linux/backing-dev.h>
18#include <linux/blkdev.h>
19#include <linux/fs_context.h>
20#include "mtdcore.h"
21
22/*
23 * get a superblock on an MTD-backed filesystem
24 */
25static int mtd_get_sb(struct fs_context *fc,
26 struct mtd_info *mtd,
27 int (*fill_super)(struct super_block *,
28 struct fs_context *))
29{
30 struct super_block *sb;
31 int ret;
32
33 sb = sget_dev(fc, MKDEV(MTD_BLOCK_MAJOR, mtd->index));
34 if (IS_ERR(sb))
35 return PTR_ERR(sb);
36
37 if (sb->s_root) {
38 /* new mountpoint for an already mounted superblock */
39 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
40 mtd->index, mtd->name);
41 put_mtd_device(mtd);
42 } else {
43 /* fresh new superblock */
44 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
45 mtd->index, mtd->name);
46
47 /*
48 * Would usually have been set with @sb_lock held but in
49 * contrast to sb->s_bdev that's checked with only
50 * @sb_lock held, nothing checks sb->s_mtd without also
51 * holding sb->s_umount and we're holding sb->s_umount
52 * here.
53 */
54 sb->s_mtd = mtd;
55 sb->s_bdi = bdi_get(mtd_bdi);
56
57 ret = fill_super(sb, fc);
58 if (ret < 0)
59 goto error_sb;
60
61 sb->s_flags |= SB_ACTIVE;
62 }
63
64 BUG_ON(fc->root);
65 fc->root = dget(sb->s_root);
66 return 0;
67
68error_sb:
69 deactivate_locked_super(sb);
70 return ret;
71}
72
73/*
74 * get a superblock on an MTD-backed filesystem by MTD device number
75 */
76static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
77 int (*fill_super)(struct super_block *,
78 struct fs_context *))
79{
80 struct mtd_info *mtd;
81
82 mtd = get_mtd_device(NULL, mtdnr);
83 if (IS_ERR(mtd)) {
84 errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
85 return PTR_ERR(mtd);
86 }
87
88 return mtd_get_sb(fc, mtd, fill_super);
89}
90
91/**
92 * get_tree_mtd - Get a superblock based on a single MTD device
93 * @fc: The filesystem context holding the parameters
94 * @fill_super: Helper to initialise a new superblock
95 */
96int get_tree_mtd(struct fs_context *fc,
97 int (*fill_super)(struct super_block *sb,
98 struct fs_context *fc))
99{
100#ifdef CONFIG_BLOCK
101 dev_t dev;
102 int ret;
103#endif
104 int mtdnr;
105
106 if (!fc->source)
107 return invalf(fc, "No source specified");
108
109 pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
110
111 /* the preferred way of mounting in future; especially when
112 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
113 * by name, so that we don't require block device support to be present
114 * in the kernel.
115 */
116 if (fc->source[0] == 'm' &&
117 fc->source[1] == 't' &&
118 fc->source[2] == 'd') {
119 if (fc->source[3] == ':') {
120 struct mtd_info *mtd;
121
122 /* mount by MTD device name */
123 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
124 fc->source + 4);
125
126 mtd = get_mtd_device_nm(fc->source + 4);
127 if (!IS_ERR(mtd))
128 return mtd_get_sb(fc, mtd, fill_super);
129
130 errorf(fc, "MTD: MTD device with name \"%s\" not found",
131 fc->source + 4);
132
133 } else if (isdigit(fc->source[3])) {
134 /* mount by MTD device number name */
135 char *endptr;
136
137 mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
138 if (!*endptr) {
139 /* It was a valid number */
140 pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
141 return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
142 }
143 }
144 }
145
146#ifdef CONFIG_BLOCK
147 /* try the old way - the hack where we allowed users to mount
148 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
149 */
150 ret = lookup_bdev(fc->source, &dev);
151 if (ret) {
152 errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
153 return ret;
154 }
155 pr_debug("MTDSB: lookup_bdev() returned 0\n");
156
157 if (MAJOR(dev) == MTD_BLOCK_MAJOR)
158 return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);
159
160#endif /* CONFIG_BLOCK */
161
162 if (!(fc->sb_flags & SB_SILENT))
163 errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
164 fc->source);
165 return -EINVAL;
166}
167EXPORT_SYMBOL_GPL(get_tree_mtd);
168
169/*
170 * destroy an MTD-based superblock
171 */
172void kill_mtd_super(struct super_block *sb)
173{
174 generic_shutdown_super(sb);
175 put_mtd_device(sb->s_mtd);
176 sb->s_mtd = NULL;
177}
178
179EXPORT_SYMBOL_GPL(kill_mtd_super);
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/ctype.h>
18#include <linux/slab.h>
19
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);
50 sb->s_bdi = mtd->backing_dev_info;
51 return 0;
52}
53
54/*
55 * get a superblock on an MTD-backed filesystem
56 */
57static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
58 const char *dev_name, void *data,
59 struct mtd_info *mtd,
60 int (*fill_super)(struct super_block *, void *, int))
61{
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
76 sb->s_flags = flags;
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 DEBUG(1, "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 DEBUG(0, "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 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
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 DEBUG(1, "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 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
183 return ERR_PTR(ret);
184 }
185 DEBUG(1, "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);