1 /* MTD-based superblock management
3 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
4 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
6 * Written by: David Howells <dhowells@redhat.com>
7 * David Woodhouse <dwmw2@infradead.org>
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.
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 #include <linux/major.h>
21 #include <linux/backing-dev.h>
24 * compare superblocks to see if they're equivalent
25 * - they are if the underlying MTD device is the same
27 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
29 struct mtd_info *mtd = _mtd;
31 if (sb->s_mtd == mtd) {
32 pr_debug("MTDSB: Match on device %d (\"%s\")\n",
33 mtd->index, mtd->name);
37 pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
38 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
42 extern struct backing_dev_info *mtd_bdi;
45 * mark the superblock by the MTD device it is using
46 * - set the device number to be the correct MTD block device for pesuperstence
49 static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
51 struct mtd_info *mtd = _mtd;
54 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
55 sb->s_bdi = bdi_get(mtd_bdi);
61 * get a superblock on an MTD-backed filesystem
63 static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
64 const char *dev_name, void *data,
66 int (*fill_super)(struct super_block *, void *, int))
68 struct super_block *sb;
71 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
78 /* fresh new superblock */
79 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
80 mtd->index, mtd->name);
82 ret = fill_super(sb, data, flags & SB_SILENT ? 1 : 0);
84 deactivate_locked_super(sb);
89 sb->s_flags |= SB_ACTIVE;
90 return dget(sb->s_root);
92 /* new mountpoint for an already mounted superblock */
94 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
95 mtd->index, mtd->name);
97 return dget(sb->s_root);
105 * get a superblock on an MTD-backed filesystem by MTD device number
107 static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
108 const char *dev_name, void *data, int mtdnr,
109 int (*fill_super)(struct super_block *, void *, int))
111 struct mtd_info *mtd;
113 mtd = get_mtd_device(NULL, mtdnr);
115 pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
116 return ERR_CAST(mtd);
119 return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
123 * set up an MTD-based superblock
125 struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
126 const char *dev_name, void *data,
127 int (*fill_super)(struct super_block *, void *, int))
130 struct block_device *bdev;
136 return ERR_PTR(-EINVAL);
138 pr_debug("MTDSB: dev_name \"%s\"\n", dev_name);
140 /* the preferred way of mounting in future; especially when
141 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
142 * by name, so that we don't require block device support to be present
144 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
145 if (dev_name[3] == ':') {
146 struct mtd_info *mtd;
148 /* mount by MTD device name */
149 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
152 mtd = get_mtd_device_nm(dev_name + 4);
154 return mount_mtd_aux(
159 printk(KERN_NOTICE "MTD:"
160 " MTD device with name \"%s\" not found.\n",
163 } else if (isdigit(dev_name[3])) {
164 /* mount by MTD device number name */
167 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
169 /* It was a valid number */
170 pr_debug("MTDSB: mtd%%d, mtdnr %d\n",
172 return mount_mtd_nr(fs_type, flags,
180 /* try the old way - the hack where we allowed users to mount
181 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
183 bdev = lookup_bdev(dev_name);
186 pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
189 pr_debug("MTDSB: lookup_bdev() returned 0\n");
193 major = MAJOR(bdev->bd_dev);
194 mtdnr = MINOR(bdev->bd_dev);
197 if (major != MTD_BLOCK_MAJOR)
198 goto not_an_MTD_device;
200 return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
203 #endif /* CONFIG_BLOCK */
205 if (!(flags & SB_SILENT))
207 "MTD: Attempt to mount non-MTD device \"%s\"\n",
209 return ERR_PTR(-EINVAL);
212 EXPORT_SYMBOL_GPL(mount_mtd);
215 * destroy an MTD-based superblock
217 void kill_mtd_super(struct super_block *sb)
219 generic_shutdown_super(sb);
220 put_mtd_device(sb->s_mtd);
224 EXPORT_SYMBOL_GPL(kill_mtd_super);