summaryrefslogtreecommitdiff
path: root/drivers/mtd/mtdsuper.c
blob: b7e3763c47f0cdf6d27b8145ffbb26b281179311 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
// SPDX-License-Identifier: GPL-2.0-or-later
/* MTD-based superblock management
 *
 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * Written by:  David Howells <dhowells@redhat.com>
 *              David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/mtd/super.h>
#include <linux/namei.h>
#include <linux/export.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/major.h>
#include <linux/backing-dev.h>
#include <linux/blkdev.h>
#include <linux/fs_context.h>
#include "mtdcore.h"

/*
 * get a superblock on an MTD-backed filesystem
 */
static int mtd_get_sb(struct fs_context *fc,
		      struct mtd_info *mtd,
		      int (*fill_super)(struct super_block *,
					struct fs_context *))
{
	struct super_block *sb;
	int ret;

	sb = sget_dev(fc, MKDEV(MTD_BLOCK_MAJOR, mtd->index));
	if (IS_ERR(sb))
		return PTR_ERR(sb);

	if (sb->s_root) {
		/* new mountpoint for an already mounted superblock */
		pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
			 mtd->index, mtd->name);
		put_mtd_device(mtd);
	} else {
		/* fresh new superblock */
		pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
			 mtd->index, mtd->name);

		/*
		 * Would usually have been set with @sb_lock held but in
		 * contrast to sb->s_bdev that's checked with only
		 * @sb_lock held, nothing checks sb->s_mtd without also
		 * holding sb->s_umount and we're holding sb->s_umount
		 * here.
		 */
		sb->s_mtd = mtd;
		sb->s_bdi = bdi_get(mtd_bdi);

		ret = fill_super(sb, fc);
		if (ret < 0)
			goto error_sb;

		sb->s_flags |= SB_ACTIVE;
	}

	BUG_ON(fc->root);
	fc->root = dget(sb->s_root);
	return 0;

error_sb:
	deactivate_locked_super(sb);
	return ret;
}

/*
 * get a superblock on an MTD-backed filesystem by MTD device number
 */
static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
			    int (*fill_super)(struct super_block *,
					      struct fs_context *))
{
	struct mtd_info *mtd;

	mtd = get_mtd_device(NULL, mtdnr);
	if (IS_ERR(mtd)) {
		errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
		return PTR_ERR(mtd);
	}

	return mtd_get_sb(fc, mtd, fill_super);
}

/**
 * get_tree_mtd - Get a superblock based on a single MTD device
 * @fc: The filesystem context holding the parameters
 * @fill_super: Helper to initialise a new superblock
 */
int get_tree_mtd(struct fs_context *fc,
	      int (*fill_super)(struct super_block *sb,
				struct fs_context *fc))
{
#ifdef CONFIG_BLOCK
	dev_t dev;
	int ret;
#endif
	int mtdnr;

	if (!fc->source)
		return invalf(fc, "No source specified");

	pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);

	/* the preferred way of mounting in future; especially when
	 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
	 * by name, so that we don't require block device support to be present
	 * in the kernel.
	 */
	if (fc->source[0] == 'm' &&
	    fc->source[1] == 't' &&
	    fc->source[2] == 'd') {
		if (fc->source[3] == ':') {
			struct mtd_info *mtd;

			/* mount by MTD device name */
			pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
				 fc->source + 4);

			mtd = get_mtd_device_nm(fc->source + 4);
			if (!IS_ERR(mtd))
				return mtd_get_sb(fc, mtd, fill_super);

			errorf(fc, "MTD: MTD device with name \"%s\" not found",
			       fc->source + 4);

		} else if (isdigit(fc->source[3])) {
			/* mount by MTD device number name */
			char *endptr;

			mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
			if (!*endptr) {
				/* It was a valid number */
				pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
				return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
			}
		}
	}

#ifdef CONFIG_BLOCK
	/* try the old way - the hack where we allowed users to mount
	 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
	 */
	ret = lookup_bdev(fc->source, &dev);
	if (ret) {
		errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
		return ret;
	}
	pr_debug("MTDSB: lookup_bdev() returned 0\n");

	if (MAJOR(dev) == MTD_BLOCK_MAJOR)
		return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);

#endif /* CONFIG_BLOCK */

	if (!(fc->sb_flags & SB_SILENT))
		errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
		       fc->source);
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(get_tree_mtd);

/*
 * destroy an MTD-based superblock
 */
void kill_mtd_super(struct super_block *sb)
{
	generic_shutdown_super(sb);
	put_mtd_device(sb->s_mtd);
	sb->s_mtd = NULL;
}

EXPORT_SYMBOL_GPL(kill_mtd_super);