drivers/mtd/mtdsuper.c

   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         ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
  74         if (ret < 0) {
  75                 up_write(&sb->s_umount);
  76                 deactivate_super(sb);
  77                 return ret;
  78         }
  79
  80         /* go */
  81         sb->s_flags |= MS_ACTIVE;
  82         return simple_set_mnt(mnt, sb);
  83
  84         /* new mountpoint for an already mounted superblock */
  85 already_mounted:
  86         DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
  87               mtd->index, mtd->name);
  88         ret = simple_set_mnt(mnt, sb);
  89         goto out_put;
  90
  91 out_error:
  92         ret = PTR_ERR(sb);
  93 out_put:
  94         put_mtd_device(mtd);
  95         return ret;
  96 }
  97
  98 /*
  99  * get a superblock on an MTD-backed filesystem by MTD device number
 100  */
 101 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
 102                          const char *dev_name, void *data, int mtdnr,
 103                          int (*fill_super)(struct super_block *, void *, int),
 104                          struct vfsmount *mnt)
 105 {
 106         struct mtd_info *mtd;
 107
 108         mtd = get_mtd_device(NULL, mtdnr);
 109         if (IS_ERR(mtd)) {
 110                 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
 111                 return PTR_ERR(mtd);
 112         }
 113
 114         return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
 115                               mnt);
 116 }
 117
 118 /*
 119  * set up an MTD-based superblock
 120  */
 121 int get_sb_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                struct vfsmount *mnt)
 125 {
 126         struct nameidata nd;
 127         int mtdnr, ret;
 128
 129         if (!dev_name)
 130                 return -EINVAL;
 131
 132         DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
 133
 134         /* the preferred way of mounting in future; especially when
 135          * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
 136          * by name, so that we don't require block device support to be present
 137          * in the kernel. */
 138         if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
 139                 if (dev_name[3] == ':') {
 140                         struct mtd_info *mtd;
 141
 142                         /* mount by MTD device name */
 143                         DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
 144                               dev_name + 4);
 145
 146                         for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
 147                                 mtd = get_mtd_device(NULL, mtdnr);
 148                                 if (!IS_ERR(mtd)) {
 149                                         if (!strcmp(mtd->name, dev_name + 4))
 150                                                 return get_sb_mtd_aux(
 151                                                         fs_type, flags,
 152                                                         dev_name, data, mtd,
 153                                                         fill_super, mnt);
 154
 155                                         put_mtd_device(mtd);
 156                                 }
 157                         }
 158
 159                         printk(KERN_NOTICE "MTD:"
 160                                " MTD device with name \"%s\" not found.\n",
 161                                dev_name + 4);
 162
 163                 } else if (isdigit(dev_name[3])) {
 164                         /* mount by MTD device number name */
 165                         char *endptr;
 166
 167                         mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
 168                         if (!*endptr) {
 169                                 /* It was a valid number */
 170                                 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
 171                                       mtdnr);
 172                                 return get_sb_mtd_nr(fs_type, flags,
 173                                                      dev_name, data,
 174                                                      mtdnr, fill_super, mnt);
 175                         }
 176                 }
 177         }
 178
 179         /* try the old way - the hack where we allowed users to mount
 180          * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
 181          */
 182         ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
 183
 184         DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n",
 185               ret, nd.dentry ? nd.dentry->d_inode : NULL);
 186
 187         if (ret)
 188                 return ret;
 189
 190         ret = -EINVAL;
 191
 192         if (!S_ISBLK(nd.dentry->d_inode->i_mode))
 193                 goto out;
 194
 195         if (nd.mnt->mnt_flags & MNT_NODEV) {
 196                 ret = -EACCES;
 197                 goto out;
 198         }
 199
 200         if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR)
 201                 goto not_an_MTD_device;
 202
 203         mtdnr = iminor(nd.dentry->d_inode);
 204         path_release(&nd);
 205
 206         return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
 207                              mnt);
 208
 209 not_an_MTD_device:
 210         if (!(flags & MS_SILENT))
 211                 printk(KERN_NOTICE
 212                        "MTD: Attempt to mount non-MTD device \"%s\"\n",
 213                        dev_name);
 214 out:
 215         path_release(&nd);
 216         return ret;
 217
 218 }
 219
 220 EXPORT_SYMBOL_GPL(get_sb_mtd);
 221
 222 /*
 223  * destroy an MTD-based superblock
 224  */
 225 void kill_mtd_super(struct super_block *sb)
 226 {
 227         generic_shutdown_super(sb);
 228         put_mtd_device(sb->s_mtd);
 229         sb->s_mtd = NULL;
 230 }
 231
 232 EXPORT_SYMBOL_GPL(kill_mtd_super);