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