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 #include <linux/slab.h>
  17
  18 /*
  19  * compare superblocks to see if they're equivalent
  20  * - they are if the underlying MTD device is the same
  21  */
  22 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
  23 {
  24         struct mtd_info *mtd = _mtd;
  25
  26         if (sb->s_mtd == mtd) {
  27                 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
  28                       mtd->index, mtd->name);
  29                 return 1;
  30         }
  31
  32         DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
  33               sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
  34         return 0;
  35 }
  36
  37 /*
  38  * mark the superblock by the MTD device it is using
  39  * - set the device number to be the correct MTD block device for pesuperstence
  40  *   of NFS exports
  41  */
  42 static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
  43 {
  44         struct mtd_info *mtd = _mtd;
  45
  46         sb->s_mtd = mtd;
  47         sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
  48         sb->s_bdi = mtd->backing_dev_info;
  49         return 0;
  50 }
  51
  52 /*
  53  * get a superblock on an MTD-backed filesystem
  54  */
  55 static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
  56                           const char *dev_name, void *data,
  57                           struct mtd_info *mtd,
  58                           int (*fill_super)(struct super_block *, void *, int),
  59                           struct vfsmount *mnt)
  60 {
  61         struct super_block *sb;
  62         int ret;
  63
  64         sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
  65         if (IS_ERR(sb))
  66                 goto out_error;
  67
  68         if (sb->s_root)
  69                 goto already_mounted;
  70
  71         /* fresh new superblock */
  72         DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
  73               mtd->index, mtd->name);
  74
  75         sb->s_flags = flags;
  76
  77         ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
  78         if (ret < 0) {
  79                 deactivate_locked_super(sb);
  80                 return ret;
  81         }
  82
  83         /* go */
  84         sb->s_flags |= MS_ACTIVE;
  85         simple_set_mnt(mnt, sb);
  86
  87         return 0;
  88
  89         /* new mountpoint for an already mounted superblock */
  90 already_mounted:
  91         DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
  92               mtd->index, mtd->name);
  93         simple_set_mnt(mnt, sb);
  94         ret = 0;
  95         goto out_put;
  96
  97 out_error:
  98         ret = PTR_ERR(sb);
  99 out_put:
 100         put_mtd_device(mtd);
 101         return ret;
 102 }
 103
 104 /*
 105  * get a superblock on an MTD-backed filesystem by MTD device number
 106  */
 107 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
 108                          const char *dev_name, void *data, int mtdnr,
 109                          int (*fill_super)(struct super_block *, void *, int),
 110                          struct vfsmount *mnt)
 111 {
 112         struct mtd_info *mtd;
 113
 114         mtd = get_mtd_device(NULL, mtdnr);
 115         if (IS_ERR(mtd)) {
 116                 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
 117                 return PTR_ERR(mtd);
 118         }
 119
 120         return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
 121                               mnt);
 122 }
 123
 124 /*
 125  * set up an MTD-based superblock
 126  */
 127 int get_sb_mtd(struct file_system_type *fs_type, int flags,
 128                const char *dev_name, void *data,
 129                int (*fill_super)(struct super_block *, void *, int),
 130                struct vfsmount *mnt)
 131 {
 132 #ifdef CONFIG_BLOCK
 133         struct block_device *bdev;
 134         int ret, major;
 135 #endif
 136         int mtdnr;
 137
 138         if (!dev_name)
 139                 return -EINVAL;
 140
 141         DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
 142
 143         /* the preferred way of mounting in future; especially when
 144          * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
 145          * by name, so that we don't require block device support to be present
 146          * in the kernel. */
 147         if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
 148                 if (dev_name[3] == ':') {
 149                         struct mtd_info *mtd;
 150
 151                         /* mount by MTD device name */
 152                         DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
 153                               dev_name + 4);
 154
 155                         mtd = get_mtd_device_nm(dev_name + 4);
 156                         if (!IS_ERR(mtd))
 157                                 return get_sb_mtd_aux(
 158                                         fs_type, flags,
 159                                         dev_name, data, mtd,
 160                                         fill_super, mnt);
 161
 162                         printk(KERN_NOTICE "MTD:"
 163                                " MTD device with name \"%s\" not found.\n",
 164                                dev_name + 4);
 165
 166                 } else if (isdigit(dev_name[3])) {
 167                         /* mount by MTD device number name */
 168                         char *endptr;
 169
 170                         mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
 171                         if (!*endptr) {
 172                                 /* It was a valid number */
 173                                 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
 174                                       mtdnr);
 175                                 return get_sb_mtd_nr(fs_type, flags,
 176                                                      dev_name, data,
 177                                                      mtdnr, fill_super, mnt);
 178                         }
 179                 }
 180         }
 181
 182 #ifdef CONFIG_BLOCK
 183         /* try the old way - the hack where we allowed users to mount
 184          * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
 185          */
 186         bdev = lookup_bdev(dev_name);
 187         if (IS_ERR(bdev)) {
 188                 ret = PTR_ERR(bdev);
 189                 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
 190                 return ret;
 191         }
 192         DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
 193
 194         ret = -EINVAL;
 195
 196         major = MAJOR(bdev->bd_dev);
 197         mtdnr = MINOR(bdev->bd_dev);
 198         bdput(bdev);
 199
 200         if (major != MTD_BLOCK_MAJOR)
 201                 goto not_an_MTD_device;
 202
 203         return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
 204                              mnt);
 205
 206 not_an_MTD_device:
 207 #endif /* CONFIG_BLOCK */
 208
 209         if (!(flags & MS_SILENT))
 210                 printk(KERN_NOTICE
 211                        "MTD: Attempt to mount non-MTD device \"%s\"\n",
 212                        dev_name);
 213         return -EINVAL;
 214 }
 215
 216 EXPORT_SYMBOL_GPL(get_sb_mtd);
 217
 218 /*
 219  * destroy an MTD-based superblock
 220  */
 221 void kill_mtd_super(struct super_block *sb)
 222 {
 223         generic_shutdown_super(sb);
 224         put_mtd_device(sb->s_mtd);
 225         sb->s_mtd = NULL;
 226 }
 227
 228 EXPORT_SYMBOL_GPL(kill_mtd_super);