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 simple_set_mnt(mnt, sb); 85 86 return 0; 87 88 /* new mountpoint for an already mounted superblock */ 89 already_mounted: 90 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n", 91 mtd->index, mtd->name); 92 simple_set_mnt(mnt, sb); 93 ret = 0; 94 goto out_put; 95 96 out_error: 97 ret = PTR_ERR(sb); 98 out_put: 99 put_mtd_device(mtd); 100 return ret; 101 } 102 103 /* 104 * get a superblock on an MTD-backed filesystem by MTD device number 105 */ 106 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags, 107 const char *dev_name, void *data, int mtdnr, 108 int (*fill_super)(struct super_block *, void *, int), 109 struct vfsmount *mnt) 110 { 111 struct mtd_info *mtd; 112 113 mtd = get_mtd_device(NULL, mtdnr); 114 if (IS_ERR(mtd)) { 115 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr); 116 return PTR_ERR(mtd); 117 } 118 119 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super, 120 mnt); 121 } 122 123 /* 124 * set up an MTD-based superblock 125 */ 126 int get_sb_mtd(struct file_system_type *fs_type, int flags, 127 const char *dev_name, void *data, 128 int (*fill_super)(struct super_block *, void *, int), 129 struct vfsmount *mnt) 130 { 131 #ifdef CONFIG_BLOCK 132 struct block_device *bdev; 133 int ret, major; 134 #endif 135 int mtdnr; 136 137 if (!dev_name) 138 return -EINVAL; 139 140 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name); 141 142 /* the preferred way of mounting in future; especially when 143 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or 144 * by name, so that we don't require block device support to be present 145 * in the kernel. */ 146 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') { 147 if (dev_name[3] == ':') { 148 struct mtd_info *mtd; 149 150 /* mount by MTD device name */ 151 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n", 152 dev_name + 4); 153 154 for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) { 155 mtd = get_mtd_device(NULL, mtdnr); 156 if (!IS_ERR(mtd)) { 157 if (!strcmp(mtd->name, dev_name + 4)) 158 return get_sb_mtd_aux( 159 fs_type, flags, 160 dev_name, data, mtd, 161 fill_super, mnt); 162 163 put_mtd_device(mtd); 164 } 165 } 166 167 printk(KERN_NOTICE "MTD:" 168 " MTD device with name \"%s\" not found.\n", 169 dev_name + 4); 170 171 } else if (isdigit(dev_name[3])) { 172 /* mount by MTD device number name */ 173 char *endptr; 174 175 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0); 176 if (!*endptr) { 177 /* It was a valid number */ 178 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n", 179 mtdnr); 180 return get_sb_mtd_nr(fs_type, flags, 181 dev_name, data, 182 mtdnr, fill_super, mnt); 183 } 184 } 185 } 186 187 #ifdef CONFIG_BLOCK 188 /* try the old way - the hack where we allowed users to mount 189 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev 190 */ 191 bdev = lookup_bdev(dev_name); 192 if (IS_ERR(bdev)) { 193 ret = PTR_ERR(bdev); 194 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret); 195 return ret; 196 } 197 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n"); 198 199 ret = -EINVAL; 200 201 major = MAJOR(bdev->bd_dev); 202 mtdnr = MINOR(bdev->bd_dev); 203 bdput(bdev); 204 205 if (major != MTD_BLOCK_MAJOR) 206 goto not_an_MTD_device; 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 #endif /* CONFIG_BLOCK */ 213 214 if (!(flags & MS_SILENT)) 215 printk(KERN_NOTICE 216 "MTD: Attempt to mount non-MTD device \"%s\"\n", 217 dev_name); 218 return -EINVAL; 219 } 220 221 EXPORT_SYMBOL_GPL(get_sb_mtd); 222 223 /* 224 * destroy an MTD-based superblock 225 */ 226 void kill_mtd_super(struct super_block *sb) 227 { 228 generic_shutdown_super(sb); 229 put_mtd_device(sb->s_mtd); 230 sb->s_mtd = NULL; 231 } 232 233 EXPORT_SYMBOL_GPL(kill_mtd_super); 234