/* MTD-based superblock management
   *
   * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
   * Written by:  David Howells <dhowells@redhat.com>
   *              David Woodhouse <dwmw2@infradead.org>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <linux/mtd/super.h>
  #include <linux/namei.h>
  #include <linux/ctype.h>
  
  /*
   * compare superblocks to see if they're equivalent
   * - they are if the underlying MTD device is the same
   */
  static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
  {
  	struct mtd_info *mtd = _mtd;
  
  	if (sb->s_mtd == mtd) {
  		DEBUG(2, "MTDSB: Match on device %d (\"%s\")
  ",
  		      mtd->index, mtd->name);
  		return 1;
  	}
  
  	DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")
  ",
  	      sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
  	return 0;
  }
  
  /*
   * mark the superblock by the MTD device it is using
   * - set the device number to be the correct MTD block device for pesuperstence
   *   of NFS exports
   */
  static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
  {
  	struct mtd_info *mtd = _mtd;
  
  	sb->s_mtd = mtd;
  	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
  	return 0;
  }
  
  /*
   * get a superblock on an MTD-backed filesystem
   */
  static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
  			  const char *dev_name, void *data,
  			  struct mtd_info *mtd,
  			  int (*fill_super)(struct super_block *, void *, int),
  			  struct vfsmount *mnt)
  {
  	struct super_block *sb;
  	int ret;
  
  	sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
  	if (IS_ERR(sb))
  		goto out_error;
  
  	if (sb->s_root)
  		goto already_mounted;
  
  	/* fresh new superblock */
  	DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")
  ",
  	      mtd->index, mtd->name);

  	sb->s_flags = flags;

  	ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
  	if (ret < 0) {
  		up_write(&sb->s_umount);
  		deactivate_super(sb);
  		return ret;
  	}
  
  	/* go */
  	sb->s_flags |= MS_ACTIVE;
  	return simple_set_mnt(mnt, sb);
  
  	/* new mountpoint for an already mounted superblock */
  already_mounted:
  	DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted
  ",
  	      mtd->index, mtd->name);
  	ret = simple_set_mnt(mnt, sb);
  	goto out_put;
  
  out_error:
  	ret = PTR_ERR(sb);
  out_put:
  	put_mtd_device(mtd);
  	return ret;
  }
  
  /*
   * get a superblock on an MTD-backed filesystem by MTD device number
   */
  static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
  			 const char *dev_name, void *data, int mtdnr,
  			 int (*fill_super)(struct super_block *, void *, int),
  			 struct vfsmount *mnt)
  {
  	struct mtd_info *mtd;
  
  	mtd = get_mtd_device(NULL, mtdnr);

  	if (IS_ERR(mtd)) {

  		DEBUG(0, "MTDSB: Device #%u doesn't appear to exist
  ", mtdnr);

  		return PTR_ERR(mtd);

  	}
  
  	return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
  			      mnt);
  }
  
  /*
   * set up an MTD-based superblock
   */
  int get_sb_mtd(struct file_system_type *fs_type, int flags,
  	       const char *dev_name, void *data,
  	       int (*fill_super)(struct super_block *, void *, int),
  	       struct vfsmount *mnt)
  {
  	struct nameidata nd;
  	int mtdnr, ret;
  
  	if (!dev_name)
  		return -EINVAL;
  
  	DEBUG(2, "MTDSB: dev_name \"%s\"
  ", dev_name);
  
  	/* the preferred way of mounting in future; especially when
  	 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
  	 * by name, so that we don't require block device support to be present
  	 * in the kernel. */
  	if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
  		if (dev_name[3] == ':') {
  			struct mtd_info *mtd;
  
  			/* mount by MTD device name */
  			DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"
  ",
  			      dev_name + 4);
  
  			for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
  				mtd = get_mtd_device(NULL, mtdnr);

  				if (!IS_ERR(mtd)) {

  					if (!strcmp(mtd->name, dev_name + 4))
  						return get_sb_mtd_aux(
  							fs_type, flags,
  							dev_name, data, mtd,
  							fill_super, mnt);
  
  					put_mtd_device(mtd);
  				}
  			}
  
  			printk(KERN_NOTICE "MTD:"
  			       " MTD device with name \"%s\" not found.
  ",
  			       dev_name + 4);
  
  		} else if (isdigit(dev_name[3])) {
  			/* mount by MTD device number name */
  			char *endptr;
  
  			mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
  			if (!*endptr) {
  				/* It was a valid number */
  				DEBUG(1, "MTDSB: mtd%%d, mtdnr %d
  ",
  				      mtdnr);
  				return get_sb_mtd_nr(fs_type, flags,
  						     dev_name, data,
  						     mtdnr, fill_super, mnt);
  			}
  		}
  	}
  
  	/* try the old way - the hack where we allowed users to mount
  	 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
  	 */
  	ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
  
  	DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p
  ",

  	      ret, nd.path.dentry ? nd.path.dentry->d_inode : NULL);

  
  	if (ret)
  		return ret;
  
  	ret = -EINVAL;

  	if (!S_ISBLK(nd.path.dentry->d_inode->i_mode))

  		goto out;

  	if (nd.path.mnt->mnt_flags & MNT_NODEV) {

  		ret = -EACCES;
  		goto out;
  	}

  	if (imajor(nd.path.dentry->d_inode) != MTD_BLOCK_MAJOR)

  		goto not_an_MTD_device;

  	mtdnr = iminor(nd.path.dentry->d_inode);

  	path_put(&nd.path);

  
  	return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
  			     mnt);
  
  not_an_MTD_device:
  	if (!(flags & MS_SILENT))
  		printk(KERN_NOTICE
  		       "MTD: Attempt to mount non-MTD device \"%s\"
  ",
  		       dev_name);
  out:

  	path_put(&nd.path);

  	return ret;
  
  }
  
  EXPORT_SYMBOL_GPL(get_sb_mtd);
  
  /*
   * destroy an MTD-based superblock
   */
  void kill_mtd_super(struct super_block *sb)
  {
  	generic_shutdown_super(sb);
  	put_mtd_device(sb->s_mtd);
  	sb->s_mtd = NULL;
  }
  
  EXPORT_SYMBOL_GPL(kill_mtd_super);