drivers/mtd/mtdsuper.c

   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/ctype.h>
  18 #include <linux/slab.h>
  19
  20 /*
  21  * compare superblocks to see if they're equivalent
  22  * - they are if the underlying MTD device is the same
  23  */
  24 static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
  25 {
  26         struct mtd_info *mtd = _mtd;
  27
  28         if (sb->s_mtd == mtd) {
  29                 DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
  30                       mtd->index, mtd->name);
  31                 return 1;
  32         }
  33
  34         DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
  35               sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
  36         return 0;
  37 }
  38
  39 /*
  40  * mark the superblock by the MTD device it is using
  41  * - set the device number to be the correct MTD block device for pesuperstence
  42  *   of NFS exports
  43  */
  44 static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
  45 {
  46         struct mtd_info *mtd = _mtd;
  47
  48         sb->s_mtd = mtd;
  49         sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
  50         sb->s_bdi = mtd->backing_dev_info;
  51         return 0;
  52 }
  53
  54 /*
  55  * get a superblock on an MTD-backed filesystem
  56  */
  57 static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
  58                           const char *dev_name, void *data,
  59                           struct mtd_info *mtd,
  60                           int (*fill_super)(struct super_block *, void *, int),
  61                           struct vfsmount *mnt)
  62 {
  63         struct super_block *sb;
  64         int ret;
  65
  66         sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
  67         if (IS_ERR(sb))
  68                 goto out_error;
  69
  70         if (sb->s_root)
  71                 goto already_mounted;
  72
  73         /* fresh new superblock */
  74         DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
  75               mtd->index, mtd->name);
  76
  77         sb->s_flags = flags;
  78
  79         ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
  80         if (ret < 0) {
  81                 deactivate_locked_super(sb);
  82                 return ret;
  83         }
  84
  85         /* go */
  86         sb->s_flags |= MS_ACTIVE;
  87         simple_set_mnt(mnt, sb);
  88
  89         return 0;
  90
  91         /* new mountpoint for an already mounted superblock */
  92 already_mounted:
  93         DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
  94               mtd->index, mtd->name);
  95         simple_set_mnt(mnt, sb);
  96         ret = 0;
  97         goto out_put;
  98
  99 out_error:
 100         ret = PTR_ERR(sb);
 101 out_put:
 102         put_mtd_device(mtd);
 103         return ret;
 104 }
 105
 106 /*
 107  * get a superblock on an MTD-backed filesystem by MTD device number
 108  */
 109 static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
 110                          const char *dev_name, void *data, int mtdnr,
 111                          int (*fill_super)(struct super_block *, void *, int),
 112                          struct vfsmount *mnt)
 113 {
 114         struct mtd_info *mtd;
 115
 116         mtd = get_mtd_device(NULL, mtdnr);
 117         if (IS_ERR(mtd)) {
 118                 DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
 119                 return PTR_ERR(mtd);
 120         }
 121
 122         return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
 123                               mnt);
 124 }
 125
 126 /*
 127  * set up an MTD-based superblock
 128  */
 129 int get_sb_mtd(struct file_system_type *fs_type, int flags,
 130                const char *dev_name, void *data,
 131                int (*fill_super)(struct super_block *, void *, int),
 132                struct vfsmount *mnt)
 133 {
 134 #ifdef CONFIG_BLOCK
 135         struct block_device *bdev;
 136         int ret, major;
 137 #endif
 138         int mtdnr;
 139
 140         if (!dev_name)
 141                 return -EINVAL;
 142
 143         DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
 144
 145         /* the preferred way of mounting in future; especially when
 146          * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
 147          * by name, so that we don't require block device support to be present
 148          * in the kernel. */
 149         if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
 150                 if (dev_name[3] == ':') {
 151                         struct mtd_info *mtd;
 152
 153                         /* mount by MTD device name */
 154                         DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
 155                               dev_name + 4);
 156
 157                         mtd = get_mtd_device_nm(dev_name + 4);
 158                         if (!IS_ERR(mtd))
 159                                 return get_sb_mtd_aux(
 160                                         fs_type, flags,
 161                                         dev_name, data, mtd,
 162                                         fill_super, mnt);
 163
 164                         printk(KERN_NOTICE "MTD:"
 165                                " MTD device with name \"%s\" not found.\n",
 166                                dev_name + 4);
 167
 168                 } else if (isdigit(dev_name[3])) {
 169                         /* mount by MTD device number name */
 170                         char *endptr;
 171
 172                         mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
 173                         if (!*endptr) {
 174                                 /* It was a valid number */
 175                                 DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
 176                                       mtdnr);
 177                                 return get_sb_mtd_nr(fs_type, flags,
 178                                                      dev_name, data,
 179                                                      mtdnr, fill_super, mnt);
 180                         }
 181                 }
 182         }
 183
 184 #ifdef CONFIG_BLOCK
 185         /* try the old way - the hack where we allowed users to mount
 186          * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
 187          */
 188         bdev = lookup_bdev(dev_name);
 189         if (IS_ERR(bdev)) {
 190                 ret = PTR_ERR(bdev);
 191                 DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
 192                 return ret;
 193         }
 194         DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
 195
 196         ret = -EINVAL;
 197
 198         major = MAJOR(bdev->bd_dev);
 199         mtdnr = MINOR(bdev->bd_dev);
 200         bdput(bdev);
 201
 202         if (major != MTD_BLOCK_MAJOR)
 203                 goto not_an_MTD_device;
 204
 205         return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
 206                              mnt);
 207
 208 not_an_MTD_device:
 209 #endif /* CONFIG_BLOCK */
 210
 211         if (!(flags & MS_SILENT))
 212                 printk(KERN_NOTICE
 213                        "MTD: Attempt to mount non-MTD device \"%s\"\n",
 214                        dev_name);
 215         return -EINVAL;
 216 }
 217
 218 EXPORT_SYMBOL_GPL(get_sb_mtd);
 219
 220 /*
 221  * destroy an MTD-based superblock
 222  */
 223 void kill_mtd_super(struct super_block *sb)
 224 {
 225         generic_shutdown_super(sb);
 226         put_mtd_device(sb->s_mtd);
 227         sb->s_mtd = NULL;
 228 }
 229
 230 EXPORT_SYMBOL_GPL(kill_mtd_super);