1 /* MTD-based superblock management 2 * 3 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved. 4 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org> 5 * 6 * Written by: David Howells <dhowells@redhat.com> 7 * David Woodhouse <dwmw2@infradead.org> 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 */ 14 15 #include <linux/mtd/super.h> 16 #include <linux/namei.h> 17 #include <linux/ctype.h> 18 #include <linux/slab.h> 19 20 /* 21 * compare superblocks to see if they're equivalent 22 * - they are if the underlying MTD device is the same 23 */ 24 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd) 25 { 26 struct mtd_info *mtd = _mtd; 27 28 if (sb->s_mtd == mtd) { 29 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n", 30 mtd->index, mtd->name); 31 return 1; 32 } 33 34 DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n", 35 sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name); 36 return 0; 37 } 38 39 /* 40 * mark the superblock by the MTD device it is using 41 * - set the device number to be the correct MTD block device for pesuperstence 42 * of NFS exports 43 */ 44 static int get_sb_mtd_set(struct super_block *sb, void *_mtd) 45 { 46 struct mtd_info *mtd = _mtd; 47 48 sb->s_mtd = mtd; 49 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index); 50 sb->s_bdi = mtd->backing_dev_info; 51 return 0; 52 } 53 54 /* 55 * get a superblock on an MTD-backed filesystem 56 */ 57 static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags, 58 const char *dev_name, void *data, 59 struct mtd_info *mtd, 60 int (*fill_super)(struct super_block *, void *, int), 61 struct vfsmount *mnt) 62 { 63 struct super_block *sb; 64 int ret; 65 66 sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd); 67 if (IS_ERR(sb)) 68 goto out_error; 69 70 if (sb->s_root) 71 goto already_mounted; 72 73 /* fresh new superblock */ 74 DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n", 75 mtd->index, mtd->name); 76 77 sb->s_flags = flags; 78 79 ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); 80 if (ret < 0) { 81 deactivate_locked_super(sb); 82 return ret; 83 } 84 85 /* go */ 86 sb->s_flags |= MS_ACTIVE; 87 simple_set_mnt(mnt, sb); 88 89 return 0; 90 91 /* new mountpoint for an already mounted superblock */ 92 already_mounted: 93 DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n", 94 mtd->index, mtd->name); 95 simple_set_mnt(mnt, sb); 96 ret = 0; 97 goto out_put; 98 99 out_error: 100 ret = PTR_ERR(sb); 101 out_put: 102 put_mtd_device(mtd); 103 return ret; 104 } 105 106 /* 107 * get a superblock on an MTD-backed filesystem by MTD device number 108 */ 109 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags, 110 const char *dev_name, void *data, int mtdnr, 111 int (*fill_super)(struct super_block *, void *, int), 112 struct vfsmount *mnt) 113 { 114 struct mtd_info *mtd; 115 116 mtd = get_mtd_device(NULL, mtdnr); 117 if (IS_ERR(mtd)) { 118 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr); 119 return PTR_ERR(mtd); 120 } 121 122 return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super, 123 mnt); 124 } 125 126 /* 127 * set up an MTD-based superblock 128 */ 129 int get_sb_mtd(struct file_system_type *fs_type, int flags, 130 const char *dev_name, void *data, 131 int (*fill_super)(struct super_block *, void *, int), 132 struct vfsmount *mnt) 133 { 134 #ifdef CONFIG_BLOCK 135 struct block_device *bdev; 136 int ret, major; 137 #endif 138 int mtdnr; 139 140 if (!dev_name) 141 return -EINVAL; 142 143 DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name); 144 145 /* the preferred way of mounting in future; especially when 146 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or 147 * by name, so that we don't require block device support to be present 148 * in the kernel. */ 149 if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') { 150 if (dev_name[3] == ':') { 151 struct mtd_info *mtd; 152 153 /* mount by MTD device name */ 154 DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n", 155 dev_name + 4); 156 157 mtd = get_mtd_device_nm(dev_name + 4); 158 if (!IS_ERR(mtd)) 159 return get_sb_mtd_aux( 160 fs_type, flags, 161 dev_name, data, mtd, 162 fill_super, mnt); 163 164 printk(KERN_NOTICE "MTD:" 165 " MTD device with name \"%s\" not found.\n", 166 dev_name + 4); 167 168 } else if (isdigit(dev_name[3])) { 169 /* mount by MTD device number name */ 170 char *endptr; 171 172 mtdnr = simple_strtoul(dev_name + 3, &endptr, 0); 173 if (!*endptr) { 174 /* It was a valid number */ 175 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n", 176 mtdnr); 177 return get_sb_mtd_nr(fs_type, flags, 178 dev_name, data, 179 mtdnr, fill_super, mnt); 180 } 181 } 182 } 183 184 #ifdef CONFIG_BLOCK 185 /* try the old way - the hack where we allowed users to mount 186 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev 187 */ 188 bdev = lookup_bdev(dev_name); 189 if (IS_ERR(bdev)) { 190 ret = PTR_ERR(bdev); 191 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret); 192 return ret; 193 } 194 DEBUG(1, "MTDSB: lookup_bdev() returned 0\n"); 195 196 ret = -EINVAL; 197 198 major = MAJOR(bdev->bd_dev); 199 mtdnr = MINOR(bdev->bd_dev); 200 bdput(bdev); 201 202 if (major != MTD_BLOCK_MAJOR) 203 goto not_an_MTD_device; 204 205 return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super, 206 mnt); 207 208 not_an_MTD_device: 209 #endif /* CONFIG_BLOCK */ 210 211 if (!(flags & MS_SILENT)) 212 printk(KERN_NOTICE 213 "MTD: Attempt to mount non-MTD device \"%s\"\n", 214 dev_name); 215 return -EINVAL; 216 } 217 218 EXPORT_SYMBOL_GPL(get_sb_mtd); 219 220 /* 221 * destroy an MTD-based superblock 222 */ 223 void kill_mtd_super(struct super_block *sb) 224 { 225 generic_shutdown_super(sb); 226 put_mtd_device(sb->s_mtd); 227 sb->s_mtd = NULL; 228 } 229 230 EXPORT_SYMBOL_GPL(kill_mtd_super); 231