Loading...
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/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);