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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/fs_context.h>
19#include "mtdcore.h"
20
21/*
22 * compare superblocks to see if they're equivalent
23 * - they are if the underlying MTD device is the same
24 */
25static int mtd_test_super(struct super_block *sb, struct fs_context *fc)
26{
27 struct mtd_info *mtd = fc->sget_key;
28
29 if (sb->s_mtd == fc->sget_key) {
30 pr_debug("MTDSB: Match on device %d (\"%s\")\n",
31 mtd->index, mtd->name);
32 return 1;
33 }
34
35 pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
36 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
37 return 0;
38}
39
40/*
41 * mark the superblock by the MTD device it is using
42 * - set the device number to be the correct MTD block device for pesuperstence
43 * of NFS exports
44 */
45static int mtd_set_super(struct super_block *sb, struct fs_context *fc)
46{
47 sb->s_mtd = fc->sget_key;
48 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
49 sb->s_bdi = bdi_get(mtd_bdi);
50 return 0;
51}
52
53/*
54 * get a superblock on an MTD-backed filesystem
55 */
56static int mtd_get_sb(struct fs_context *fc,
57 struct mtd_info *mtd,
58 int (*fill_super)(struct super_block *,
59 struct fs_context *))
60{
61 struct super_block *sb;
62 int ret;
63
64 fc->sget_key = mtd;
65 sb = sget_fc(fc, mtd_test_super, mtd_set_super);
66 if (IS_ERR(sb))
67 return PTR_ERR(sb);
68
69 if (sb->s_root) {
70 /* new mountpoint for an already mounted superblock */
71 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
72 mtd->index, mtd->name);
73 put_mtd_device(mtd);
74 } else {
75 /* fresh new superblock */
76 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
77 mtd->index, mtd->name);
78
79 ret = fill_super(sb, fc);
80 if (ret < 0)
81 goto error_sb;
82
83 sb->s_flags |= SB_ACTIVE;
84 }
85
86 BUG_ON(fc->root);
87 fc->root = dget(sb->s_root);
88 return 0;
89
90error_sb:
91 deactivate_locked_super(sb);
92 return ret;
93}
94
95/*
96 * get a superblock on an MTD-backed filesystem by MTD device number
97 */
98static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
99 int (*fill_super)(struct super_block *,
100 struct fs_context *))
101{
102 struct mtd_info *mtd;
103
104 mtd = get_mtd_device(NULL, mtdnr);
105 if (IS_ERR(mtd)) {
106 errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
107 return PTR_ERR(mtd);
108 }
109
110 return mtd_get_sb(fc, mtd, fill_super);
111}
112
113/**
114 * get_tree_mtd - Get a superblock based on a single MTD device
115 * @fc: The filesystem context holding the parameters
116 * @fill_super: Helper to initialise a new superblock
117 */
118int get_tree_mtd(struct fs_context *fc,
119 int (*fill_super)(struct super_block *sb,
120 struct fs_context *fc))
121{
122#ifdef CONFIG_BLOCK
123 struct block_device *bdev;
124 int ret, major;
125#endif
126 int mtdnr;
127
128 if (!fc->source)
129 return invalf(fc, "No source specified");
130
131 pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
132
133 /* the preferred way of mounting in future; especially when
134 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
135 * by name, so that we don't require block device support to be present
136 * in the kernel.
137 */
138 if (fc->source[0] == 'm' &&
139 fc->source[1] == 't' &&
140 fc->source[2] == 'd') {
141 if (fc->source[3] == ':') {
142 struct mtd_info *mtd;
143
144 /* mount by MTD device name */
145 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
146 fc->source + 4);
147
148 mtd = get_mtd_device_nm(fc->source + 4);
149 if (!IS_ERR(mtd))
150 return mtd_get_sb(fc, mtd, fill_super);
151
152 errorf(fc, "MTD: MTD device with name \"%s\" not found",
153 fc->source + 4);
154
155 } else if (isdigit(fc->source[3])) {
156 /* mount by MTD device number name */
157 char *endptr;
158
159 mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
160 if (!*endptr) {
161 /* It was a valid number */
162 pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
163 return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
164 }
165 }
166 }
167
168#ifdef CONFIG_BLOCK
169 /* try the old way - the hack where we allowed users to mount
170 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
171 */
172 bdev = lookup_bdev(fc->source);
173 if (IS_ERR(bdev)) {
174 ret = PTR_ERR(bdev);
175 errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
176 return ret;
177 }
178 pr_debug("MTDSB: lookup_bdev() returned 0\n");
179
180 major = MAJOR(bdev->bd_dev);
181 mtdnr = MINOR(bdev->bd_dev);
182 bdput(bdev);
183
184 if (major == MTD_BLOCK_MAJOR)
185 return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
186
187#endif /* CONFIG_BLOCK */
188
189 if (!(fc->sb_flags & SB_SILENT))
190 errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
191 fc->source);
192 return -EINVAL;
193}
194EXPORT_SYMBOL_GPL(get_tree_mtd);
195
196/*
197 * destroy an MTD-based superblock
198 */
199void kill_mtd_super(struct super_block *sb)
200{
201 generic_shutdown_super(sb);
202 put_mtd_device(sb->s_mtd);
203 sb->s_mtd = NULL;
204}
205
206EXPORT_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/export.h>
18#include <linux/ctype.h>
19#include <linux/slab.h>
20#include <linux/major.h>
21
22/*
23 * compare superblocks to see if they're equivalent
24 * - they are if the underlying MTD device is the same
25 */
26static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
27{
28 struct mtd_info *mtd = _mtd;
29
30 if (sb->s_mtd == mtd) {
31 pr_debug("MTDSB: Match on device %d (\"%s\")\n",
32 mtd->index, mtd->name);
33 return 1;
34 }
35
36 pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
37 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
38 return 0;
39}
40
41/*
42 * mark the superblock by the MTD device it is using
43 * - set the device number to be the correct MTD block device for pesuperstence
44 * of NFS exports
45 */
46static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
47{
48 struct mtd_info *mtd = _mtd;
49
50 sb->s_mtd = mtd;
51 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
52 sb->s_bdi = mtd->backing_dev_info;
53 return 0;
54}
55
56/*
57 * get a superblock on an MTD-backed filesystem
58 */
59static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
60 const char *dev_name, void *data,
61 struct mtd_info *mtd,
62 int (*fill_super)(struct super_block *, void *, int))
63{
64 struct super_block *sb;
65 int ret;
66
67 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
68 if (IS_ERR(sb))
69 goto out_error;
70
71 if (sb->s_root)
72 goto already_mounted;
73
74 /* fresh new superblock */
75 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
76 mtd->index, mtd->name);
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 pr_debug("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 pr_debug("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 pr_debug("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 pr_debug("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 pr_debug("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 pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
183 return ERR_PTR(ret);
184 }
185 pr_debug("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);