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 deactivate_locked_super(sb); 78 return ret; 79 } 80 81 /* go */ 82 sb->s_flags |= MS_ACTIVE; 83 simple_set_mnt(mnt, sb); 84 85 return 0; 86 87 /* new mountpoint for an already mounted superblock */ 88 already_mounted: 89 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n", 90 mtd->index, mtd->name); 91 simple_set_mnt(mnt, sb); 92 ret = 0; 93 goto out_put; 94 95 out_error: 96 ret = PTR_ERR(sb); 97 out_put: 98 put_mtd_device(mtd); 99 return ret; 100 } 101 102 /* 103 * get a superblock on an MTD-backed filesystem by MTD device number 104 */ 105 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags, 106 const char *dev_name, void *data, int mtdnr, 107 int (*fill_super)(struct super_block *, void *, int), 108 struct vfsmount *mnt) 109 { 110 struct mtd_info *mtd; 111 112 mtd = get_mtd_device(NULL, mtdnr); 113 if (IS_ERR(mtd)) { 114 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr); 115 return PTR_ERR(mtd); 116 } 117 118 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super, 119 mnt); 120 } 121 122 /* 123 * set up an MTD-based superblock 124 */ 125 int get_sb_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), 128 struct vfsmount *mnt) 129 { 130 #ifdef CONFIG_BLOCK 131 struct block_device *bdev; 132 int ret, major; 133 #endif 134 int mtdnr; 135 136 if (!dev_name) 137 return -EINVAL; 138 139 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name); 140 141 /* the preferred way of mounting in future; especially when 142 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or 143 * by name, so that we don't require block device support to be present 144 * in the kernel. */ 145 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') { 146 if (dev_name[3] == ':') { 147 struct mtd_info *mtd; 148 149 /* mount by MTD device name */ 150 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n", 151 dev_name + 4); 152 153 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) { 154 mtd = get_mtd_device(NULL, mtdnr); 155 if (!IS_ERR(mtd)) { 156 if (!strcmp(mtd->name, dev_name + 4)) 157 return get_sb_mtd_aux( 158 fs_type, flags, 159 dev_name, data, mtd, 160 fill_super, mnt); 161 162 put_mtd_device(mtd); 163 } 164 } 165 166 printk(KERN_NOTICE "MTD:" 167 " MTD device with name \"%s\" not found.\n", 168 dev_name + 4); 169 170 } else if (isdigit(dev_name[3])) { 171 /* mount by MTD device number name */ 172 char *endptr; 173 174 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0); 175 if (!*endptr) { 176 /* It was a valid number */ 177 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n", 178 mtdnr); 179 return get_sb_mtd_nr(fs_type, flags, 180 dev_name, data, 181 mtdnr, fill_super, mnt); 182 } 183 } 184 } 185 186 #ifdef CONFIG_BLOCK 187 /* try the old way - the hack where we allowed users to mount 188 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev 189 */ 190 bdev = lookup_bdev(dev_name); 191 if (IS_ERR(bdev)) { 192 ret = PTR_ERR(bdev); 193 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret); 194 return ret; 195 } 196 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n"); 197 198 ret = -EINVAL; 199 200 major = MAJOR(bdev->bd_dev); 201 mtdnr = MINOR(bdev->bd_dev); 202 bdput(bdev); 203 204 if (major != MTD_BLOCK_MAJOR) 205 goto not_an_MTD_device; 206 207 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super, 208 mnt); 209 210 not_an_MTD_device: 211 #endif /* CONFIG_BLOCK */ 212 213 if (!(flags & MS_SILENT)) 214 printk(KERN_NOTICE 215 "MTD: Attempt to mount non-MTD device \"%s\"\n", 216 dev_name); 217 return -EINVAL; 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