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 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 74 if (ret < 0) { 75 up_write(&sb->s_umount); 76 deactivate_super(sb); 77 return ret; 78 } 79 80 /* go */ 81 sb->s_flags |= MS_ACTIVE; 82 return simple_set_mnt(mnt, sb); 83 84 /* new mountpoint for an already mounted superblock */ 85 already_mounted: 86 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n", 87 mtd->index, mtd->name); 88 ret = simple_set_mnt(mnt, sb); 89 goto out_put; 90 91 out_error: 92 ret = PTR_ERR(sb); 93 out_put: 94 put_mtd_device(mtd); 95 return ret; 96 } 97 98 /* 99 * get a superblock on an MTD-backed filesystem by MTD device number 100 */ 101 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags, 102 const char *dev_name, void *data, int mtdnr, 103 int (*fill_super)(struct super_block *, void *, int), 104 struct vfsmount *mnt) 105 { 106 struct mtd_info *mtd; 107 108 mtd = get_mtd_device(NULL, mtdnr); 109 if (IS_ERR(mtd)) { 110 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr); 111 return PTR_ERR(mtd); 112 } 113 114 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super, 115 mnt); 116 } 117 118 /* 119 * set up an MTD-based superblock 120 */ 121 int get_sb_mtd(struct file_system_type *fs_type, int flags, 122 const char *dev_name, void *data, 123 int (*fill_super)(struct super_block *, void *, int), 124 struct vfsmount *mnt) 125 { 126 struct nameidata nd; 127 int mtdnr, ret; 128 129 if (!dev_name) 130 return -EINVAL; 131 132 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name); 133 134 /* 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 137 * in the kernel. */ 138 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') { 139 if (dev_name[3] == ':') { 140 struct mtd_info *mtd; 141 142 /* mount by MTD device name */ 143 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n", 144 dev_name + 4); 145 146 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) { 147 mtd = get_mtd_device(NULL, mtdnr); 148 if (!IS_ERR(mtd)) { 149 if (!strcmp(mtd->name, dev_name + 4)) 150 return get_sb_mtd_aux( 151 fs_type, flags, 152 dev_name, data, mtd, 153 fill_super, mnt); 154 155 put_mtd_device(mtd); 156 } 157 } 158 159 printk(KERN_NOTICE "MTD:" 160 " MTD device with name \"%s\" not found.\n", 161 dev_name + 4); 162 163 } else if (isdigit(dev_name[3])) { 164 /* mount by MTD device number name */ 165 char *endptr; 166 167 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0); 168 if (!*endptr) { 169 /* It was a valid number */ 170 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n", 171 mtdnr); 172 return get_sb_mtd_nr(fs_type, flags, 173 dev_name, data, 174 mtdnr, fill_super, mnt); 175 } 176 } 177 } 178 179 /* try the old way - the hack where we allowed users to mount 180 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev 181 */ 182 ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd); 183 184 DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n", 185 ret, nd.dentry ? nd.dentry->d_inode : NULL); 186 187 if (ret) 188 return ret; 189 190 ret = -EINVAL; 191 192 if (!S_ISBLK(nd.dentry->d_inode->i_mode)) 193 goto out; 194 195 if (nd.mnt->mnt_flags & MNT_NODEV) { 196 ret = -EACCES; 197 goto out; 198 } 199 200 if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR) 201 goto not_an_MTD_device; 202 203 mtdnr = iminor(nd.dentry->d_inode); 204 path_release(&nd); 205 206 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super, 207 mnt); 208 209 not_an_MTD_device: 210 if (!(flags & MS_SILENT)) 211 printk(KERN_NOTICE 212 "MTD: Attempt to mount non-MTD device \"%s\"\n", 213 dev_name); 214 out: 215 path_release(&nd); 216 return ret; 217 218 } 219 220 EXPORT_SYMBOL_GPL(get_sb_mtd); 221 222 /* 223 * destroy an MTD-based superblock 224 */ 225 void kill_mtd_super(struct super_block *sb) 226 { 227 generic_shutdown_super(sb); 228 put_mtd_device(sb->s_mtd); 229 sb->s_mtd = NULL; 230 } 231 232 EXPORT_SYMBOL_GPL(kill_mtd_super); 233