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