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