mtdsuper.c 5.63 KB
Newer Older
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
/* MTD-based superblock management
 *
 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
 * Written by:  David Howells <dhowells@redhat.com>
 *              David Woodhouse <dwmw2@infradead.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/mtd/super.h>
#include <linux/namei.h>
#include <linux/ctype.h>

/*
 * compare superblocks to see if they're equivalent
 * - they are if the underlying MTD device is the same
 */
static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
{
	struct mtd_info *mtd = _mtd;

	if (sb->s_mtd == mtd) {
		DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
		      mtd->index, mtd->name);
		return 1;
	}

	DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
	      sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
	return 0;
}

/*
 * mark the superblock by the MTD device it is using
 * - set the device number to be the correct MTD block device for pesuperstence
 *   of NFS exports
 */
static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
{
	struct mtd_info *mtd = _mtd;

	sb->s_mtd = mtd;
	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
	return 0;
}

/*
 * get a superblock on an MTD-backed filesystem
 */
static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
			  const char *dev_name, void *data,
			  struct mtd_info *mtd,
			  int (*fill_super)(struct super_block *, void *, int),
			  struct vfsmount *mnt)
{
	struct super_block *sb;
	int ret;

	sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
	if (IS_ERR(sb))
		goto out_error;

	if (sb->s_root)
		goto already_mounted;

	/* fresh new superblock */
	DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
	      mtd->index, mtd->name);

73 74
	sb->s_flags = flags;

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
	ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
	if (ret < 0) {
		up_write(&sb->s_umount);
		deactivate_super(sb);
		return ret;
	}

	/* go */
	sb->s_flags |= MS_ACTIVE;
	return simple_set_mnt(mnt, sb);

	/* new mountpoint for an already mounted superblock */
already_mounted:
	DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
	      mtd->index, mtd->name);
	ret = simple_set_mnt(mnt, sb);
	goto out_put;

out_error:
	ret = PTR_ERR(sb);
out_put:
	put_mtd_device(mtd);
	return ret;
}

/*
 * get a superblock on an MTD-backed filesystem by MTD device number
 */
static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
			 const char *dev_name, void *data, int mtdnr,
			 int (*fill_super)(struct super_block *, void *, int),
			 struct vfsmount *mnt)
{
	struct mtd_info *mtd;

	mtd = get_mtd_device(NULL, mtdnr);
111
	if (IS_ERR(mtd)) {
112
		DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
113
		return PTR_ERR(mtd);
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
	}

	return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
			      mnt);
}

/*
 * set up an MTD-based superblock
 */
int get_sb_mtd(struct file_system_type *fs_type, int flags,
	       const char *dev_name, void *data,
	       int (*fill_super)(struct super_block *, void *, int),
	       struct vfsmount *mnt)
{
	struct nameidata nd;
	int mtdnr, ret;

	if (!dev_name)
		return -EINVAL;

	DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);

	/* 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 (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
		if (dev_name[3] == ':') {
			struct mtd_info *mtd;

			/* mount by MTD device name */
			DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
			      dev_name + 4);

			for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
				mtd = get_mtd_device(NULL, mtdnr);
150
				if (!IS_ERR(mtd)) {
151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186
					if (!strcmp(mtd->name, dev_name + 4))
						return get_sb_mtd_aux(
							fs_type, flags,
							dev_name, data, mtd,
							fill_super, mnt);

					put_mtd_device(mtd);
				}
			}

			printk(KERN_NOTICE "MTD:"
			       " MTD device with name \"%s\" not found.\n",
			       dev_name + 4);

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

			mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
			if (!*endptr) {
				/* It was a valid number */
				DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
				      mtdnr);
				return get_sb_mtd_nr(fs_type, flags,
						     dev_name, data,
						     mtdnr, fill_super, mnt);
			}
		}
	}

	/* try the old way - the hack where we allowed users to mount
	 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
	 */
	ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);

	DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n",
187
	      ret, nd.path.dentry ? nd.path.dentry->d_inode : NULL);
188 189 190 191 192 193

	if (ret)
		return ret;

	ret = -EINVAL;

194
	if (!S_ISBLK(nd.path.dentry->d_inode->i_mode))
195 196
		goto out;

197
	if (nd.path.mnt->mnt_flags & MNT_NODEV) {
198 199 200 201
		ret = -EACCES;
		goto out;
	}

202
	if (imajor(nd.path.dentry->d_inode) != MTD_BLOCK_MAJOR)
203 204
		goto not_an_MTD_device;

205
	mtdnr = iminor(nd.path.dentry->d_inode);
206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234
	path_release(&nd);

	return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
			     mnt);

not_an_MTD_device:
	if (!(flags & MS_SILENT))
		printk(KERN_NOTICE
		       "MTD: Attempt to mount non-MTD device \"%s\"\n",
		       dev_name);
out:
	path_release(&nd);
	return ret;

}

EXPORT_SYMBOL_GPL(get_sb_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);