super.c

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			return MKDEV(UNNAMED_MAJOR, i);
	}
	printk("VFS: Sorry, out of unnamed devices\n");
	return 0;
}

void put_unnamed_dev(kdev_t dev)
{
	if (!dev)
		return;
	if (MAJOR(dev) == UNNAMED_MAJOR &&
	    clear_bit(MINOR(dev), unnamed_dev_in_use))
		return;
	printk("VFS: put_unnamed_dev: freeing unused device %s\n",
			kdevname(dev));
}

static int do_umount(kdev_t dev,int unmount_root)
{
	struct super_block * sb;
	int retval;
	
	if (dev==ROOT_DEV && !unmount_root) {
		/*
		 * Special case for "unmounting" root. We just try to remount
		 * it readonly, and sync() the device.
		 */
		if (!(sb=get_super(dev)))
			return -ENOENT;
		if (!(sb->s_flags & MS_RDONLY)) {
			/*
			 * Make sure all quotas are turned off on this device we need to mount
			 * it readonly so no more writes by the quotasystem.
			 * If later on the remount fails too bad there are no quotas running
			 * anymore. Turn them on again by hand.
			 */
			quota_off(dev, -1);
			fsync_dev(dev);
			retval = do_remount_sb(sb, MS_RDONLY, 0);
			if (retval)
				return retval;
		}
		return 0;
	}
	if (!(sb=get_super(dev)) || !(sb->s_covered))
		return -ENOENT;
	if (!sb->s_covered->i_mount)
		printk("VFS: umount(%s): mounted inode has i_mount=NULL\n",
		       kdevname(dev));
	/*
	 * Before checking if the filesystem is still busy make sure the kernel
	 * doesn't hold any quotafiles open on that device. If the umount fails
	 * too bad there are no quotas running anymore. Turn them on again by hand.
	 */
	quota_off(dev, -1);
	if (!fs_may_umount(dev, sb->s_mounted))
		return -EBUSY;
	sb->s_covered->i_mount = NULL;
	iput(sb->s_covered);
	sb->s_covered = NULL;
	iput(sb->s_mounted);
	sb->s_mounted = NULL;
	if (sb->s_op && sb->s_op->write_super && sb->s_dirt)
		sb->s_op->write_super(sb);
	put_super(dev);
	remove_vfsmnt(dev);
	return 0;
}

/*
 * Now umount can handle mount points as well as block devices.
 * This is important for filesystems which use unnamed block devices.
 *
 * There is a little kludge here with the dummy_inode.  The current
 * vfs release functions only use the r_dev field in the inode so
 * we give them the info they need without using a real inode.
 * If any other fields are ever needed by any block device release
 * functions, they should be faked here.  -- jrs
 */

asmlinkage int sys_umount(char * name)
{
	struct inode * inode;
	kdev_t dev;
	int retval;
	struct inode dummy_inode;

	if (!suser())
		return -EPERM;
	retval = namei(name, &inode);
	if (retval) {
		retval = lnamei(name, &inode);
		if (retval)
			return retval;
	}
	if (S_ISBLK(inode->i_mode)) {
		dev = inode->i_rdev;
		if (IS_NODEV(inode)) {
			iput(inode);
			return -EACCES;
		}
	} else {
		if (!inode->i_sb || inode != inode->i_sb->s_mounted) {
			iput(inode);
			return -EINVAL;
		}
		dev = inode->i_sb->s_dev;
		iput(inode);
		memset(&dummy_inode, 0, sizeof(dummy_inode));
		dummy_inode.i_rdev = dev;
		inode = &dummy_inode;
	}
	if (MAJOR(dev) >= MAX_BLKDEV) {
		iput(inode);
		return -ENXIO;
	}
	retval = do_umount(dev,0);
	if (!retval) {
		fsync_dev(dev);
		if (dev != ROOT_DEV) {
			blkdev_release (inode);
			if (MAJOR(dev) == UNNAMED_MAJOR)
				put_unnamed_dev(dev);
		}
	}
	if (inode != &dummy_inode)
		iput(inode);
	if (retval)
		return retval;
	fsync_dev(dev);
	return 0;
}

/*
 * do_mount() does the actual mounting after sys_mount has done the ugly
 * parameter parsing. When enough time has gone by, and everything uses the
 * new mount() parameters, sys_mount() can then be cleaned up.
 *
 * We cannot mount a filesystem if it has active, used, or dirty inodes.
 * We also have to flush all inode-data for this device, as the new mount
 * might need new info.
 */

int do_mount(kdev_t dev, const char * dev_name, const char * dir_name, const char * type, int flags, void * data)
{
	struct inode * dir_i;
	struct super_block * sb;
	struct vfsmount *vfsmnt;
	int error;

	if (!(flags & MS_RDONLY) && dev && is_read_only(dev))
		return -EACCES;
		/*flags |= MS_RDONLY;*/
	error = namei(dir_name, &dir_i);
	if (error)
		return error;
	if (dir_i->i_count != 1 || dir_i->i_mount) {
		iput(dir_i);
		return -EBUSY;
	}
	if (!S_ISDIR(dir_i->i_mode)) {
		iput(dir_i);
		return -ENOTDIR;
	}
	if (!fs_may_mount(dev)) {
		iput(dir_i);
		return -EBUSY;
	}
	sb = read_super(dev,type,flags,data,0);
	if (!sb) {
		iput(dir_i);
		return -EINVAL;
	}
	if (sb->s_covered) {
		iput(dir_i);
		return -EBUSY;
	}
	vfsmnt = add_vfsmnt(dev, dev_name, dir_name);
	if (vfsmnt) {
		vfsmnt->mnt_sb = sb;
		vfsmnt->mnt_flags = flags;
	}
	sb->s_covered = dir_i;
	dir_i->i_mount = sb->s_mounted;
	return 0;		/* we don't iput(dir_i) - see umount */
}


/*
 * Alters the mount flags of a mounted file system. Only the mount point
 * is used as a reference - file system type and the device are ignored.
 * FS-specific mount options can't be altered by remounting.
 */

static int do_remount_sb(struct super_block *sb, int flags, char *data)
{
	int retval;
	struct vfsmount *vfsmnt;
	
	if (!(flags & MS_RDONLY) && sb->s_dev && is_read_only(sb->s_dev))
		return -EACCES;
		/*flags |= MS_RDONLY;*/
	/* If we are remounting RDONLY, make sure there are no rw files open */
	if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY))
		if (!fs_may_remount_ro(sb->s_dev))
			return -EBUSY;
	if (sb->s_op && sb->s_op->remount_fs) {
		retval = sb->s_op->remount_fs(sb, &flags, data);
		if (retval)
			return retval;
	}
	sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
	vfsmnt = lookup_vfsmnt(sb->s_dev);
	if (vfsmnt)
		vfsmnt->mnt_flags = sb->s_flags;
	return 0;
}

static int do_remount(const char *dir,int flags,char *data)
{
	struct inode *dir_i;
	int retval;

	retval = namei(dir, &dir_i);
	if (retval)
		return retval;
	if (dir_i != dir_i->i_sb->s_mounted) {
		iput(dir_i);
		return -EINVAL;
	}
	retval = do_remount_sb(dir_i->i_sb, flags, data);
	iput(dir_i);
	return retval;
}

static int copy_mount_options (const void * data, unsigned long *where)
{
	int i;
	unsigned long page;
#ifndef NO_MM
	struct vm_area_struct * vma;
#endif
	*where = 0;
	if (!data)
		return 0;

#ifndef NO_MM
	vma = find_vma(current->mm, (unsigned long) data);
	if (!vma || (unsigned long) data < vma->vm_start)
		return -EFAULT;
	if (!(vma->vm_flags & VM_READ))
		return -EFAULT;
	i = vma->vm_end - (unsigned long) data;
	if (PAGE_SIZE <= (unsigned long) i)
		i = PAGE_SIZE-1;
#else
	i = PAGE_SIZE-1;
#endif
	if (!(page = __get_free_page(GFP_KERNEL))) {
		return -ENOMEM;
	}
	memcpy_fromfs((void *) page,data,i);
	*where = page;
	return 0;
}

/*
 * Flags is a 16-bit value that allows up to 16 non-fs dependent flags to
 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
 *
 * data is a (void *) that can point to any structure up to
 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
 * information (or be NULL).
 *
 * NOTE! As old versions of mount() didn't use this setup, the flags
 * has to have a special 16-bit magic number in the hight word:
 * 0xC0ED. If this magic word isn't present, the flags and data info
 * isn't used, as the syscall assumes we are talking to an older
 * version that didn't understand them.
 */
asmlinkage int sys_mount(char * dev_name, char * dir_name, char * type,
	unsigned long new_flags, void * data)
{
	struct file_system_type * fstype;
	struct inode * inode;
	struct file_operations * fops;
	kdev_t dev;
	int retval;
	const char * t;
	unsigned long flags = 0;
	unsigned long page = 0;

	if (!suser())
		return -EPERM;
	if ((new_flags &
	     (MS_MGC_MSK | MS_REMOUNT)) == (MS_MGC_VAL | MS_REMOUNT)) {
		retval = copy_mount_options (data, &page);
		if (retval < 0)
			return retval;
		retval = do_remount(dir_name,
				    new_flags & ~MS_MGC_MSK & ~MS_REMOUNT,
				    (char *) page);
		free_page(page);
		return retval;
	}
	retval = copy_mount_options (type, &page);
	if (retval < 0)
		return retval;
	fstype = get_fs_type((char *) page);
	free_page(page);
	if (!fstype)		
		return -ENODEV;
	t = fstype->name;
	fops = NULL;
	if (fstype->requires_dev) {
		retval = namei(dev_name, &inode);
		if (retval)
			return retval;
		if (!S_ISBLK(inode->i_mode)) {
			iput(inode);
			return -ENOTBLK;
		}
		if (IS_NODEV(inode)) {
			iput(inode);
			return -EACCES;
		}
		dev = inode->i_rdev;
		if (MAJOR(dev) >= MAX_BLKDEV) {
			iput(inode);
			return -ENXIO;
		}
		fops = get_blkfops(MAJOR(dev));
		if (!fops) {
			iput(inode);
			return -ENOTBLK;
		}
		if (fops->open) {
			struct file dummy;	/* allows read-write or read-only flag */
			memset(&dummy, 0, sizeof(dummy));
			dummy.f_inode = inode;
			dummy.f_mode = (new_flags & MS_RDONLY) ? 1 : 3;
			retval = fops->open(inode, &dummy);
			if (retval) {
				iput(inode);
				return retval;
			}
		}

	} else {
		if (!(dev = get_unnamed_dev()))
			return -EMFILE;
		inode = NULL;
	}
	page = 0;
	if ((new_flags & MS_MGC_MSK) == MS_MGC_VAL) {
		flags = new_flags & ~MS_MGC_MSK;
		retval = copy_mount_options(data, &page);
		if (retval < 0) {
			iput(inode);
			return retval;
		}
	}
	retval = do_mount(dev,dev_name,dir_name,t,flags,(void *) page);
	free_page(page);
	if (retval && !fstype->requires_dev) 
		put_unnamed_dev(dev);
	if (retval && fops && fops->release)
		fops->release(inode, NULL);
	iput(inode);
	return retval;
}

static void do_mount_root(void)
{
	struct file_system_type * fs_type;
	struct super_block * sb;
	struct vfsmount *vfsmnt;
	struct inode * inode, d_inode;
	struct file filp;
	int retval;
  
#ifdef CONFIG_ROOT_NFS
	if (MAJOR(ROOT_DEV) == UNNAMED_MAJOR)
		if (nfs_root_init(nfs_root_name, nfs_root_addrs) < 0) {
			printk(KERN_ERR "Root-NFS: Unable to contact NFS "
			    "server for root fs, using /dev/fd0 instead\n");
			ROOT_DEV = MKDEV(FLOPPY_MAJOR, 0);
		}
	if (MAJOR(ROOT_DEV) == UNNAMED_MAJOR) {
		ROOT_DEV = 0;
		if ((fs_type = get_fs_type("nfs"))) {
			sb = &super_blocks[0];
			while (sb->s_dev) sb++;
			sb->s_dev = get_unnamed_dev();
			sb->s_flags = root_mountflags & ~MS_RDONLY;
			if (nfs_root_mount(sb) >= 0) {
				inode = sb->s_mounted;
				inode->i_count += 3 ;
				sb->s_covered = inode;
				sb->s_rd_only = 0;
				sb->s_dirt = 0;
				sb->s_type = fs_type;
				current->fs->pwd = inode;
				current->fs->root = inode;
				ROOT_DEV = sb->s_dev;
				printk (KERN_NOTICE "VFS: Mounted root (nfs filesystem).\n");
				vfsmnt = add_vfsmnt(ROOT_DEV, "/dev/root", "/");
				if (!vfsmnt)
					panic("VFS: add_vfsmnt failed for NFS root.\n");
				vfsmnt->mnt_sb = sb;
				vfsmnt->mnt_flags = sb->s_flags;
				return;
			}
			sb->s_dev = 0;
		}
		if (!ROOT_DEV) {
			printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
			ROOT_DEV = MKDEV(FLOPPY_MAJOR, 0);
		}
	}
#endif

#ifdef CONFIG_BLK_DEV_FD
	if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
		extern int rd_doload;
		floppy_eject();
#ifndef CONFIG_BLK_DEV_RAM
		printk(KERN_NOTICE "(Warning, this kernel has no ramdisk support)\n");
#endif
#ifdef CONFIG_BLK_DEV_INITRD
		/* rd_doload is 2 for a dual initrd/ramload setup */
		if(rd_doload==2)
			rd_load_secondary();
		else
#endif		
		{
			printk(KERN_NOTICE "VFS: Insert root floppy and press ENTER\n");
			wait_for_keypress();
		}
	}
#endif

	memset(&filp, 0, sizeof(filp));
	memset(&d_inode, 0, sizeof(d_inode));
	d_inode.i_rdev = ROOT_DEV;
	filp.f_inode = &d_inode;
	if ( root_mountflags & MS_RDONLY)
		filp.f_mode = 1; /* read only */
	else
		filp.f_mode = 3; /* read write */
	retval = blkdev_open(&d_inode, &filp);
	if (retval == -EROFS) {
		root_mountflags |= MS_RDONLY;
		filp.f_mode = 1;
		retval = blkdev_open(&d_inode, &filp);
	}
	if (retval)
	        /*
		 * Allow the user to distinguish between failed open
		 * and bad superblock on root device.
		 */
		printk("VFS: Cannot open root device %s\n",
		       kdevname(ROOT_DEV));
	else for (fs_type = file_systems ; fs_type ; fs_type = fs_type->next) {
  		if (!fs_type->requires_dev)
  			continue;
  		sb = read_super(ROOT_DEV,fs_type->name,root_mountflags,NULL,0);
		if (sb) {
			inode = sb->s_mounted;
			inode->i_count += 3 ;	/* NOTE! it is logically used 4 times, not 1 */
			sb->s_covered = inode;
			sb->s_flags = root_mountflags;
			current->fs->pwd = inode;
			current->fs->root = inode;
			printk ("VFS: Mounted root (%s filesystem)%s.\n",
				fs_type->name,
				(sb->s_flags & MS_RDONLY) ? " readonly" : "");
			vfsmnt = add_vfsmnt(ROOT_DEV, "/dev/root", "/");
			if (!vfsmnt)
				panic("VFS: add_vfsmnt failed for root fs");
			vfsmnt->mnt_sb = sb;
			vfsmnt->mnt_flags = root_mountflags;
			return;
		}
	}
	panic("VFS: Unable to mount root fs on %s",
		kdevname(ROOT_DEV));
}


void mount_root(void)
{
	memset(super_blocks, 0, sizeof(super_blocks));
	do_mount_root();
}


#ifdef CONFIG_BLK_DEV_INITRD

int change_root(kdev_t new_root_dev,const char *put_old)
{
	kdev_t old_root_dev;
	struct vfsmount *vfsmnt;
	struct inode *old_root,*old_pwd,*inode;
	unsigned long old_fs;
	int error;

	old_root = current->fs->root;
	old_pwd = current->fs->pwd;
	old_root_dev = ROOT_DEV;
	if (!fs_may_mount(new_root_dev)) {
		printk(KERN_CRIT "New root is busy. Staying in initrd.\n");
		return -EBUSY;
	}
	ROOT_DEV = new_root_dev;
	do_mount_root();
	old_fs = get_fs();
	set_fs(get_ds());
        error = namei(put_old,&inode);
	if (error) inode = NULL;
	set_fs(old_fs);
	if (!error && (inode->i_count != 1 || inode->i_mount)) error = -EBUSY;
	if (!error && !S_ISDIR(inode->i_mode)) error = -ENOTDIR;
	iput(old_root); /* current->fs->root */
	iput(old_pwd); /* current->fs->pwd */
	if (error) {
		int umount_error;

		if (inode) iput(inode);
		printk(KERN_NOTICE "Trying to unmount old root ... ");
		old_root->i_mount = old_root;
			/* does this belong into do_mount_root ? */
		umount_error = do_umount(old_root_dev,1);
		if (umount_error) printk(KERN_ERR "error %d\n",umount_error);
		else {
			printk("okay\n");
			invalidate_buffers(old_root_dev);
		}
		return umount_error ? error : 0;
	}
	iput(old_root); /* sb->s_covered */
	remove_vfsmnt(old_root_dev);
	vfsmnt = add_vfsmnt(old_root_dev,"/dev/root.old",put_old);
	if (!vfsmnt) printk(KERN_CRIT "Trouble: add_vfsmnt failed\n");
	else {
		vfsmnt->mnt_sb = old_root->i_sb;
		vfsmnt->mnt_sb->s_covered = inode;
		vfsmnt->mnt_flags = vfsmnt->mnt_sb->s_flags;
	}
	inode->i_mount = old_root;
	return 0;
}

#endif