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         simple_set_mnt(mnt, sb);
  85
  86         return 0;
  87
  88         /* new mountpoint for an already mounted superblock */
  89 already_mounted:
  90         DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
  91               mtd->index, mtd->name);
  92         simple_set_mnt(mnt, sb);
  93         ret = 0;
  94         goto out_put;
  95
  96 out_error:
  97         ret = PTR_ERR(sb);
  98 out_put:
  99         put_mtd_device(mtd);
 100         return ret;
 101 }
 102
 103 /*
 104  * get a superblock on an MTD-backed filesystem by MTD device number
 105  */
 106 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
 107                          const char *dev_name, void *data, int mtdnr,
 108                          int (*fill_super)(struct super_block *, void *, int),
 109                          struct vfsmount *mnt)
 110 {
 111         struct mtd_info *mtd;
 112
 113         mtd = get_mtd_device(NULL, mtdnr);
 114         if (IS_ERR(mtd)) {
 115                 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
 116                 return PTR_ERR(mtd);
 117         }
 118
 119         return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
 120                               mnt);
 121 }
 122
 123 /*
 124  * set up an MTD-based superblock
 125  */
 126 int get_sb_mtd(struct file_system_type *fs_type, int flags,
 127                const char *dev_name, void *data,
 128                int (*fill_super)(struct super_block *, void *, int),
 129                struct vfsmount *mnt)
 130 {
 131 #ifdef CONFIG_BLOCK
 132         struct block_device *bdev;
 133         int ret, major;
 134 #endif
 135         int mtdnr;
 136
 137         if (!dev_name)
 138                 return -EINVAL;
 139
 140         DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
 141
 142         /* the preferred way of mounting in future; especially when
 143          * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
 144          * by name, so that we don't require block device support to be present
 145          * in the kernel. */
 146         if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
 147                 if (dev_name[3] == ':') {
 148                         struct mtd_info *mtd;
 149
 150                         /* mount by MTD device name */
 151                         DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
 152                               dev_name + 4);
 153
 154                         for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
 155                                 mtd = get_mtd_device(NULL, mtdnr);
 156                                 if (!IS_ERR(mtd)) {
 157                                         if (!strcmp(mtd->name, dev_name + 4))
 158                                                 return get_sb_mtd_aux(
 159                                                         fs_type, flags,
 160                                                         dev_name, data, mtd,
 161                                                         fill_super, mnt);
 162
 163                                         put_mtd_device(mtd);
 164                                 }
 165                         }
 166
 167                         printk(KERN_NOTICE "MTD:"
 168                                " MTD device with name \"%s\" not found.\n",
 169                                dev_name + 4);
 170
 171                 } else if (isdigit(dev_name[3])) {
 172                         /* mount by MTD device number name */
 173                         char *endptr;
 174
 175                         mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
 176                         if (!*endptr) {
 177                                 /* It was a valid number */
 178                                 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
 179                                       mtdnr);
 180                                 return get_sb_mtd_nr(fs_type, flags,
 181                                                      dev_name, data,
 182                                                      mtdnr, fill_super, mnt);
 183                         }
 184                 }
 185         }
 186
 187 #ifdef CONFIG_BLOCK
 188         /* try the old way - the hack where we allowed users to mount
 189          * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
 190          */
 191         bdev = lookup_bdev(dev_name);
 192         if (IS_ERR(bdev)) {
 193                 ret = PTR_ERR(bdev);
 194                 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
 195                 return ret;
 196         }
 197         DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
 198
 199         ret = -EINVAL;
 200
 201         major = MAJOR(bdev->bd_dev);
 202         mtdnr = MINOR(bdev->bd_dev);
 203         bdput(bdev);
 204
 205         if (major != MTD_BLOCK_MAJOR)
 206                 goto not_an_MTD_device;
 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 #endif /* CONFIG_BLOCK */
 213
 214         if (!(flags & MS_SILENT))
 215                 printk(KERN_NOTICE
 216                        "MTD: Attempt to mount non-MTD device \"%s\"\n",
 217                        dev_name);
 218         return -EINVAL;
 219 }
 220
 221 EXPORT_SYMBOL_GPL(get_sb_mtd);
 222
 223 /*
 224  * destroy an MTD-based superblock
 225  */
 226 void kill_mtd_super(struct super_block *sb)
 227 {
 228         generic_shutdown_super(sb);
 229         put_mtd_device(sb->s_mtd);
 230         sb->s_mtd = NULL;
 231 }
 232
 233 EXPORT_SYMBOL_GPL(kill_mtd_super);