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 | */ |
25 | static 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(ptr: sb)) |
35 | return PTR_ERR(ptr: 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(bdi: 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(dentry: sb->s_root); |
66 | return 0; |
67 | |
68 | error_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 | */ |
76 | static 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, num: mtdnr); |
83 | if (IS_ERR(ptr: mtd)) { |
84 | errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n" , mtdnr); |
85 | return PTR_ERR(ptr: 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 | */ |
96 | int 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(name: fc->source + 4); |
127 | if (!IS_ERR(ptr: 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(c: 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(pathname: fc->source, dev: &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 | } |
167 | EXPORT_SYMBOL_GPL(get_tree_mtd); |
168 | |
169 | /* |
170 | * destroy an MTD-based superblock |
171 | */ |
172 | void kill_mtd_super(struct super_block *sb) |
173 | { |
174 | generic_shutdown_super(sb); |
175 | put_mtd_device(mtd: sb->s_mtd); |
176 | sb->s_mtd = NULL; |
177 | } |
178 | |
179 | EXPORT_SYMBOL_GPL(kill_mtd_super); |
180 | |