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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
21/*
22 * compare superblocks to see if they're equivalent
23 * - they are if the underlying MTD device is the same
24 */
25static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
26{
27 struct mtd_info *mtd = _mtd;
28
29 if (sb->s_mtd == mtd) {
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 get_sb_mtd_set(struct super_block *sb, void *_mtd)
46{
47 struct mtd_info *mtd = _mtd;
48
49 sb->s_mtd = mtd;
50 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
51 sb->s_bdi = mtd->backing_dev_info;
52 return 0;
53}
54
55/*
56 * get a superblock on an MTD-backed filesystem
57 */
58static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
59 const char *dev_name, void *data,
60 struct mtd_info *mtd,
61 int (*fill_super)(struct super_block *, void *, int))
62{
63 struct super_block *sb;
64 int ret;
65
66 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
67 if (IS_ERR(sb))
68 goto out_error;
69
70 if (sb->s_root)
71 goto already_mounted;
72
73 /* fresh new superblock */
74 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
75 mtd->index, mtd->name);
76
77 sb->s_flags = flags;
78
79 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
80 if (ret < 0) {
81 deactivate_locked_super(sb);
82 return ERR_PTR(ret);
83 }
84
85 /* go */
86 sb->s_flags |= MS_ACTIVE;
87 return dget(sb->s_root);
88
89 /* new mountpoint for an already mounted superblock */
90already_mounted:
91 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
92 mtd->index, mtd->name);
93 put_mtd_device(mtd);
94 return dget(sb->s_root);
95
96out_error:
97 put_mtd_device(mtd);
98 return ERR_CAST(sb);
99}
100
101/*
102 * get a superblock on an MTD-backed filesystem by MTD device number
103 */
104static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
105 const char *dev_name, void *data, int mtdnr,
106 int (*fill_super)(struct super_block *, void *, int))
107{
108 struct mtd_info *mtd;
109
110 mtd = get_mtd_device(NULL, mtdnr);
111 if (IS_ERR(mtd)) {
112 pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
113 return ERR_CAST(mtd);
114 }
115
116 return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
117}
118
119/*
120 * set up an MTD-based superblock
121 */
122struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
123 const char *dev_name, void *data,
124 int (*fill_super)(struct super_block *, void *, int))
125{
126#ifdef CONFIG_BLOCK
127 struct block_device *bdev;
128 int ret, major;
129#endif
130 int mtdnr;
131
132 if (!dev_name)
133 return ERR_PTR(-EINVAL);
134
135 pr_debug("MTDSB: dev_name \"%s\"\n", dev_name);
136
137 /* the preferred way of mounting in future; especially when
138 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
139 * by name, so that we don't require block device support to be present
140 * in the kernel. */
141 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
142 if (dev_name[3] == ':') {
143 struct mtd_info *mtd;
144
145 /* mount by MTD device name */
146 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
147 dev_name + 4);
148
149 mtd = get_mtd_device_nm(dev_name + 4);
150 if (!IS_ERR(mtd))
151 return mount_mtd_aux(
152 fs_type, flags,
153 dev_name, data, mtd,
154 fill_super);
155
156 printk(KERN_NOTICE "MTD:"
157 " MTD device with name \"%s\" not found.\n",
158 dev_name + 4);
159
160 } else if (isdigit(dev_name[3])) {
161 /* mount by MTD device number name */
162 char *endptr;
163
164 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
165 if (!*endptr) {
166 /* It was a valid number */
167 pr_debug("MTDSB: mtd%%d, mtdnr %d\n",
168 mtdnr);
169 return mount_mtd_nr(fs_type, flags,
170 dev_name, data,
171 mtdnr, fill_super);
172 }
173 }
174 }
175
176#ifdef CONFIG_BLOCK
177 /* try the old way - the hack where we allowed users to mount
178 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
179 */
180 bdev = lookup_bdev(dev_name);
181 if (IS_ERR(bdev)) {
182 ret = PTR_ERR(bdev);
183 pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
184 return ERR_PTR(ret);
185 }
186 pr_debug("MTDSB: lookup_bdev() returned 0\n");
187
188 ret = -EINVAL;
189
190 major = MAJOR(bdev->bd_dev);
191 mtdnr = MINOR(bdev->bd_dev);
192 bdput(bdev);
193
194 if (major != MTD_BLOCK_MAJOR)
195 goto not_an_MTD_device;
196
197 return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
198
199not_an_MTD_device:
200#endif /* CONFIG_BLOCK */
201
202 if (!(flags & MS_SILENT))
203 printk(KERN_NOTICE
204 "MTD: Attempt to mount non-MTD device \"%s\"\n",
205 dev_name);
206 return ERR_PTR(-EINVAL);
207}
208
209EXPORT_SYMBOL_GPL(mount_mtd);
210
211/*
212 * destroy an MTD-based superblock
213 */
214void kill_mtd_super(struct super_block *sb)
215{
216 generic_shutdown_super(sb);
217 put_mtd_device(sb->s_mtd);
218 sb->s_mtd = NULL;
219}
220
221EXPORT_SYMBOL_GPL(kill_mtd_super);