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         sb->s_flags = flags;
  74
  75         ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
  76         if (ret < 0) {
  77                 up_write(&sb->s_umount);
  78                 deactivate_super(sb);
  79                 return ret;
  80         }
  81
  82         /* go */
  83         sb->s_flags |= MS_ACTIVE;
  84         return simple_set_mnt(mnt, sb);
  85
  86         /* new mountpoint for an already mounted superblock */
  87 already_mounted:
  88         DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
  89               mtd->index, mtd->name);
  90         ret = simple_set_mnt(mnt, sb);
  91         goto out_put;
  92
  93 out_error:
  94         ret = PTR_ERR(sb);
  95 out_put:
  96         put_mtd_device(mtd);
  97         return ret;
  98 }
  99
 100 /*
 101  * get a superblock on an MTD-backed filesystem by MTD device number
 102  */
 103 static int get_sb_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                          struct vfsmount *mnt)
 107 {
 108         struct mtd_info *mtd;
 109
 110         mtd = get_mtd_device(NULL, mtdnr);
 111         if (IS_ERR(mtd)) {
 112                 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
 113                 return PTR_ERR(mtd);
 114         }
 115
 116         return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
 117                               mnt);
 118 }
 119
 120 /*
 121  * set up an MTD-based superblock
 122  */
 123 int get_sb_mtd(struct file_system_type *fs_type, int flags,
 124                const char *dev_name, void *data,
 125                int (*fill_super)(struct super_block *, void *, int),
 126                struct vfsmount *mnt)
 127 {
 128         struct nameidata nd;
 129         int mtdnr, ret;
 130
 131         if (!dev_name)
 132                 return -EINVAL;
 133
 134         DEBUG(2, "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                         DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
 146                               dev_name + 4);
 147
 148                         for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
 149                                 mtd = get_mtd_device(NULL, mtdnr);
 150                                 if (!IS_ERR(mtd)) {
 151                                         if (!strcmp(mtd->name, dev_name + 4))
 152                                                 return get_sb_mtd_aux(
 153                                                         fs_type, flags,
 154                                                         dev_name, data, mtd,
 155                                                         fill_super, mnt);
 156
 157                                         put_mtd_device(mtd);
 158                                 }
 159                         }
 160
 161                         printk(KERN_NOTICE "MTD:"
 162                                " MTD device with name \"%s\" not found.\n",
 163                                dev_name + 4);
 164
 165                 } else if (isdigit(dev_name[3])) {
 166                         /* mount by MTD device number name */
 167                         char *endptr;
 168
 169                         mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
 170                         if (!*endptr) {
 171                                 /* It was a valid number */
 172                                 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
 173                                       mtdnr);
 174                                 return get_sb_mtd_nr(fs_type, flags,
 175                                                      dev_name, data,
 176                                                      mtdnr, fill_super, mnt);
 177                         }
 178                 }
 179         }
 180
 181         /* try the old way - the hack where we allowed users to mount
 182          * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
 183          */
 184         ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
 185
 186         DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n",
 187               ret, nd.dentry ? nd.dentry->d_inode : NULL);
 188
 189         if (ret)
 190                 return ret;
 191
 192         ret = -EINVAL;
 193
 194         if (!S_ISBLK(nd.dentry->d_inode->i_mode))
 195                 goto out;
 196
 197         if (nd.mnt->mnt_flags & MNT_NODEV) {
 198                 ret = -EACCES;
 199                 goto out;
 200         }
 201
 202         if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR)
 203                 goto not_an_MTD_device;
 204
 205         mtdnr = iminor(nd.dentry->d_inode);
 206         path_release(&nd);
 207
 208         return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
 209                              mnt);
 210
 211 not_an_MTD_device:
 212         if (!(flags & MS_SILENT))
 213                 printk(KERN_NOTICE
 214                        "MTD: Attempt to mount non-MTD device \"%s\"\n",
 215                        dev_name);
 216 out:
 217         path_release(&nd);
 218         return ret;
 219
 220 }
 221
 222 EXPORT_SYMBOL_GPL(get_sb_mtd);
 223
 224 /*
 225  * destroy an MTD-based superblock
 226  */
 227 void kill_mtd_super(struct super_block *sb)
 228 {
 229         generic_shutdown_super(sb);
 230         put_mtd_device(sb->s_mtd);
 231         sb->s_mtd = NULL;
 232 }
 233
 234 EXPORT_SYMBOL_GPL(kill_mtd_super);