1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* MTD-based superblock management
4 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
5 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
7 * Written by: David Howells <dhowells@redhat.com>
8 * David Woodhouse <dwmw2@infradead.org>
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>
23 * compare superblocks to see if they're equivalent
24 * - they are if the underlying MTD device is the same
26 static int mtd_test_super(struct super_block *sb, struct fs_context *fc)
28 struct mtd_info *mtd = fc->sget_key;
30 if (sb->s_mtd == fc->sget_key) {
31 pr_debug("MTDSB: Match on device %d (\"%s\")\n",
32 mtd->index, mtd->name);
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);
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
46 static int mtd_set_super(struct super_block *sb, struct fs_context *fc)
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);
55 * get a superblock on an MTD-backed filesystem
57 static int mtd_get_sb(struct fs_context *fc,
59 int (*fill_super)(struct super_block *,
62 struct super_block *sb;
66 sb = sget_fc(fc, mtd_test_super, mtd_set_super);
71 /* new mountpoint for an already mounted superblock */
72 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
73 mtd->index, mtd->name);
76 /* fresh new superblock */
77 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
78 mtd->index, mtd->name);
80 ret = fill_super(sb, fc);
84 sb->s_flags |= SB_ACTIVE;
88 fc->root = dget(sb->s_root);
92 deactivate_locked_super(sb);
97 * get a superblock on an MTD-backed filesystem by MTD device number
99 static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
100 int (*fill_super)(struct super_block *,
101 struct fs_context *))
103 struct mtd_info *mtd;
105 mtd = get_mtd_device(NULL, mtdnr);
107 errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
111 return mtd_get_sb(fc, mtd, fill_super);
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
119 int get_tree_mtd(struct fs_context *fc,
120 int (*fill_super)(struct super_block *sb,
121 struct fs_context *fc))
130 return invalf(fc, "No source specified");
132 pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
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
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;
145 /* mount by MTD device name */
146 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
149 mtd = get_mtd_device_nm(fc->source + 4);
151 return mtd_get_sb(fc, mtd, fill_super);
153 errorf(fc, "MTD: MTD device with name \"%s\" not found",
156 } else if (isdigit(fc->source[3])) {
157 /* mount by MTD device number name */
160 mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
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);
170 /* try the old way - the hack where we allowed users to mount
171 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
173 ret = lookup_bdev(fc->source, &dev);
175 errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
178 pr_debug("MTDSB: lookup_bdev() returned 0\n");
180 if (MAJOR(dev) == MTD_BLOCK_MAJOR)
181 return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);
183 #endif /* CONFIG_BLOCK */
185 if (!(fc->sb_flags & SB_SILENT))
186 errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
190 EXPORT_SYMBOL_GPL(get_tree_mtd);
193 * destroy an MTD-based superblock
195 void kill_mtd_super(struct super_block *sb)
197 generic_shutdown_super(sb);
198 put_mtd_device(sb->s_mtd);
202 EXPORT_SYMBOL_GPL(kill_mtd_super);