1 /* MTD-based superblock management 2 * 3 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved. 4 * Written by: David Howells <dhowells@redhat.com> 5 * David Woodhouse <dwmw2@infradead.org> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12 13 #include <linux/mtd/super.h> 14 #include <linux/namei.h> 15 #include <linux/ctype.h> 16 17 /* 18 * compare superblocks to see if they're equivalent 19 * - they are if the underlying MTD device is the same 20 */ 21 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd) 22 { 23 struct mtd_info *mtd = _mtd; 24 25 if (sb->s_mtd == mtd) { 26 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n", 27 mtd->index, mtd->name); 28 return 1; 29 } 30 31 DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n", 32 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name); 33 return 0; 34 } 35 36 /* 37 * mark the superblock by the MTD device it is using 38 * - set the device number to be the correct MTD block device for pesuperstence 39 * of NFS exports 40 */ 41 static int get_sb_mtd_set(struct super_block *sb, void *_mtd) 42 { 43 struct mtd_info *mtd = _mtd; 44 45 sb->s_mtd = mtd; 46 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index); 47 return 0; 48 } 49 50 /* 51 * get a superblock on an MTD-backed filesystem 52 */ 53 static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags, 54 const char *dev_name, void *data, 55 struct mtd_info *mtd, 56 int (*fill_super)(struct super_block *, void *, int), 57 struct vfsmount *mnt) 58 { 59 struct super_block *sb; 60 int ret; 61 62 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd); 63 if (IS_ERR(sb)) 64 goto out_error; 65 66 if (sb->s_root) 67 goto already_mounted; 68 69 /* fresh new superblock */ 70 DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n", 71 mtd->index, mtd->name); 72 73 sb->s_flags = flags; 74 75 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 76 if (ret < 0) { 77 up_write(&sb->s_umount); 78 deactivate_super(sb); 79 return ret; 80 } 81 82 /* go */ 83 sb->s_flags |= MS_ACTIVE; 84 return simple_set_mnt(mnt, sb); 85 86 /* new mountpoint for an already mounted superblock */ 87 already_mounted: 88 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n", 89 mtd->index, mtd->name); 90 ret = simple_set_mnt(mnt, sb); 91 goto out_put; 92 93 out_error: 94 ret = PTR_ERR(sb); 95 out_put: 96 put_mtd_device(mtd); 97 return ret; 98 } 99 100 /* 101 * get a superblock on an MTD-backed filesystem by MTD device number 102 */ 103 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags, 104 const char *dev_name, void *data, int mtdnr, 105 int (*fill_super)(struct super_block *, void *, int), 106 struct vfsmount *mnt) 107 { 108 struct mtd_info *mtd; 109 110 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 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super, 117 mnt); 118 } 119 120 /* 121 * set up an MTD-based superblock 122 */ 123 int get_sb_mtd(struct file_system_type *fs_type, int flags, 124 const char *dev_name, void *data, 125 int (*fill_super)(struct super_block *, void *, int), 126 struct vfsmount *mnt) 127 { 128 struct nameidata nd; 129 int mtdnr, ret; 130 131 if (!dev_name) 132 return -EINVAL; 133 134 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name); 135 136 /* the preferred way of mounting in future; especially when 137 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or 138 * by name, so that we don't require block device support to be present 139 * in the kernel. */ 140 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') { 141 if (dev_name[3] == ':') { 142 struct mtd_info *mtd; 143 144 /* mount by MTD device name */ 145 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n", 146 dev_name + 4); 147 148 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) { 149 mtd = get_mtd_device(NULL, mtdnr); 150 if (!IS_ERR(mtd)) { 151 if (!strcmp(mtd->name, dev_name + 4)) 152 return get_sb_mtd_aux( 153 fs_type, flags, 154 dev_name, data, mtd, 155 fill_super, mnt); 156 157 put_mtd_device(mtd); 158 } 159 } 160 161 printk(KERN_NOTICE "MTD:" 162 " MTD device with name \"%s\" not found.\n", 163 dev_name + 4); 164 165 } else if (isdigit(dev_name[3])) { 166 /* mount by MTD device number name */ 167 char *endptr; 168 169 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0); 170 if (!*endptr) { 171 /* It was a valid number */ 172 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n", 173 mtdnr); 174 return get_sb_mtd_nr(fs_type, flags, 175 dev_name, data, 176 mtdnr, fill_super, mnt); 177 } 178 } 179 } 180 181 /* try the old way - the hack where we allowed users to mount 182 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev 183 */ 184 ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd); 185 186 DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n", 187 ret, nd.path.dentry ? nd.path.dentry->d_inode : NULL); 188 189 if (ret) 190 return ret; 191 192 ret = -EINVAL; 193 194 if (!S_ISBLK(nd.path.dentry->d_inode->i_mode)) 195 goto out; 196 197 if (nd.path.mnt->mnt_flags & MNT_NODEV) { 198 ret = -EACCES; 199 goto out; 200 } 201 202 if (imajor(nd.path.dentry->d_inode) != MTD_BLOCK_MAJOR) 203 goto not_an_MTD_device; 204 205 mtdnr = iminor(nd.path.dentry->d_inode); 206 path_put(&nd.path); 207 208 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super, 209 mnt); 210 211 not_an_MTD_device: 212 if (!(flags & MS_SILENT)) 213 printk(KERN_NOTICE 214 "MTD: Attempt to mount non-MTD device \"%s\"\n", 215 dev_name); 216 out: 217 path_put(&nd.path); 218 return ret; 219 220 } 221 222 EXPORT_SYMBOL_GPL(get_sb_mtd); 223 224 /* 225 * destroy an MTD-based superblock 226 */ 227 void kill_mtd_super(struct super_block *sb) 228 { 229 generic_shutdown_super(sb); 230 put_mtd_device(sb->s_mtd); 231 sb->s_mtd = NULL; 232 } 233 234 EXPORT_SYMBOL_GPL(kill_mtd_super); 235