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