inode.c

linux-2.6.15.6

	down(&file->f_dentry->d_inode->i_sem);
	switch(orig) {
	case 0:
		if (offset > 0) {
			file->f_pos = offset;
			retval = file->f_pos;
		} 
		break;
	case 1:
		if ((offset + file->f_pos) > 0) {
			file->f_pos += offset;
			retval = file->f_pos;
		} 
		break;
	default:
		break;
	}
	up(&file->f_dentry->d_inode->i_sem);
	return retval;
}

static int default_open (struct inode *inode, struct file *file)
{
	if (inode->u.generic_ip)
		file->private_data = inode->u.generic_ip;

	return 0;
}

static struct file_operations default_file_operations = {
	.read =		default_read_file,
	.write =	default_write_file,
	.open =		default_open,
	.llseek =	default_file_lseek,
};

static struct super_operations usbfs_ops = {
	.statfs =	simple_statfs,
	.drop_inode =	generic_delete_inode,
	.remount_fs =	remount,
};

static int usbfs_fill_super(struct super_block *sb, void *data, int silent)
{
	struct inode *inode;
	struct dentry *root;

	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = USBDEVICE_SUPER_MAGIC;
	sb->s_op = &usbfs_ops;
	sb->s_time_gran = 1;
	inode = usbfs_get_inode(sb, S_IFDIR | 0755, 0);

	if (!inode) {
		dbg("%s: could not get inode!",__FUNCTION__);
		return -ENOMEM;
	}

	root = d_alloc_root(inode);
	if (!root) {
		dbg("%s: could not get root dentry!",__FUNCTION__);
		iput(inode);
		return -ENOMEM;
	}
	sb->s_root = root;
	return 0;
}

/*
 * fs_create_by_name - create a file, given a name
 * @name:	name of file
 * @mode:	type of file
 * @parent:	dentry of directory to create it in
 * @dentry:	resulting dentry of file
 *
 * This function handles both regular files and directories.
 */
static int fs_create_by_name (const char *name, mode_t mode,
			      struct dentry *parent, struct dentry **dentry)
{
	int error = 0;

	/* If the parent is not specified, we create it in the root.
	 * We need the root dentry to do this, which is in the super 
	 * block. A pointer to that is in the struct vfsmount that we
	 * have around.
	 */
	if (!parent ) {
		if (usbfs_mount && usbfs_mount->mnt_sb) {
			parent = usbfs_mount->mnt_sb->s_root;
		}
	}

	if (!parent) {
		dbg("Ah! can not find a parent!");
		return -EFAULT;
	}

	*dentry = NULL;
	down(&parent->d_inode->i_sem);
	*dentry = lookup_one_len(name, parent, strlen(name));
	if (!IS_ERR(dentry)) {
		if ((mode & S_IFMT) == S_IFDIR)
			error = usbfs_mkdir (parent->d_inode, *dentry, mode);
		else 
			error = usbfs_create (parent->d_inode, *dentry, mode);
	} else
		error = PTR_ERR(dentry);
	up(&parent->d_inode->i_sem);

	return error;
}

static struct dentry *fs_create_file (const char *name, mode_t mode,
				      struct dentry *parent, void *data,
				      struct file_operations *fops,
				      uid_t uid, gid_t gid)
{
	struct dentry *dentry;
	int error;

	dbg("creating file '%s'",name);

	error = fs_create_by_name (name, mode, parent, &dentry);
	if (error) {
		dentry = NULL;
	} else {
		if (dentry->d_inode) {
			if (data)
				dentry->d_inode->u.generic_ip = data;
			if (fops)
				dentry->d_inode->i_fop = fops;
			dentry->d_inode->i_uid = uid;
			dentry->d_inode->i_gid = gid;
		}
	}

	return dentry;
}

static void fs_remove_file (struct dentry *dentry)
{
	struct dentry *parent = dentry->d_parent;
	
	if (!parent || !parent->d_inode)
		return;

	down(&parent->d_inode->i_sem);
	if (usbfs_positive(dentry)) {
		if (dentry->d_inode) {
			if (S_ISDIR(dentry->d_inode->i_mode))
				usbfs_rmdir(parent->d_inode, dentry);
			else
				usbfs_unlink(parent->d_inode, dentry);
		dput(dentry);
		}
	}
	up(&parent->d_inode->i_sem);
}

/* --------------------------------------------------------------------- */

static struct super_block *usb_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return get_sb_single(fs_type, flags, data, usbfs_fill_super);
}

static struct file_system_type usb_fs_type = {
	.owner =	THIS_MODULE,
	.name =		"usbfs",
	.get_sb =	usb_get_sb,
	.kill_sb =	kill_litter_super,
};

/* --------------------------------------------------------------------- */

static int create_special_files (void)
{
	struct dentry *parent;
	int retval;

	/* the simple_pin_fs calls will call remount with no options
	 * without this flag that would overwrite the real mount options (if any)
	 */
	ignore_mount = 1;

	/* create the devices special file */
	retval = simple_pin_fs("usbfs", &usbfs_mount, &usbfs_mount_count);
	if (retval) {
		err ("Unable to get usbfs mount");
		goto exit;
	}

	ignore_mount = 0;

	parent = usbfs_mount->mnt_sb->s_root;
	devices_usbfs_dentry = fs_create_file ("devices",
					       listmode | S_IFREG, parent,
					       NULL, &usbfs_devices_fops,
					       listuid, listgid);
	if (devices_usbfs_dentry == NULL) {
		err ("Unable to create devices usbfs file");
		retval = -ENODEV;
		goto error_clean_mounts;
	}

	goto exit;
	
error_clean_mounts:
	simple_release_fs(&usbfs_mount, &usbfs_mount_count);
exit:
	return retval;
}

static void remove_special_files (void)
{
	if (devices_usbfs_dentry)
		fs_remove_file (devices_usbfs_dentry);
	devices_usbfs_dentry = NULL;
	simple_release_fs(&usbfs_mount, &usbfs_mount_count);
}

void usbfs_update_special (void)
{
	struct inode *inode;

	if (devices_usbfs_dentry) {
		inode = devices_usbfs_dentry->d_inode;
		if (inode)
			inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	}
}

static void usbfs_add_bus(struct usb_bus *bus)
{
	struct dentry *parent;
	char name[8];
	int retval;

	/* create the special files if this is the first bus added */
	if (num_buses == 0) {
		retval = create_special_files();
		if (retval)
			return;
	}
	++num_buses;

	sprintf (name, "%03d", bus->busnum);

	parent = usbfs_mount->mnt_sb->s_root;
	bus->usbfs_dentry = fs_create_file (name, busmode | S_IFDIR, parent,
					    bus, NULL, busuid, busgid);
	if (bus->usbfs_dentry == NULL) {
		err ("error creating usbfs bus entry");
		return;
	}
}

static void usbfs_remove_bus(struct usb_bus *bus)
{
	if (bus->usbfs_dentry) {
		fs_remove_file (bus->usbfs_dentry);
		bus->usbfs_dentry = NULL;
	}

	--num_buses;
	if (num_buses <= 0) {
		remove_special_files();
		num_buses = 0;
	}
}

static void usbfs_add_device(struct usb_device *dev)
{
	char name[8];
	int i;
	int i_size;

	sprintf (name, "%03d", dev->devnum);
	dev->usbfs_dentry = fs_create_file (name, devmode | S_IFREG,
					    dev->bus->usbfs_dentry, dev,
					    &usbfs_device_file_operations,
					    devuid, devgid);
	if (dev->usbfs_dentry == NULL) {
		err ("error creating usbfs device entry");
		return;
	}

	/* Set the size of the device's file to be
	 * equal to the size of the device descriptors. */
	i_size = sizeof (struct usb_device_descriptor);
	for (i = 0; i < dev->descriptor.bNumConfigurations; ++i) {
		struct usb_config_descriptor *config =
			(struct usb_config_descriptor *)dev->rawdescriptors[i];
		i_size += le16_to_cpu(config->wTotalLength);
	}
	if (dev->usbfs_dentry->d_inode)
		dev->usbfs_dentry->d_inode->i_size = i_size;
}

static void usbfs_remove_device(struct usb_device *dev)
{
	struct dev_state *ds;
	struct siginfo sinfo;

	if (dev->usbfs_dentry) {
		fs_remove_file (dev->usbfs_dentry);
		dev->usbfs_dentry = NULL;
	}
	while (!list_empty(&dev->filelist)) {
		ds = list_entry(dev->filelist.next, struct dev_state, list);
		wake_up_all(&ds->wait);
		list_del_init(&ds->list);
		if (ds->discsignr) {
			sinfo.si_signo = SIGPIPE;
			sinfo.si_errno = EPIPE;
			sinfo.si_code = SI_ASYNCIO;
			sinfo.si_addr = ds->disccontext;
			kill_proc_info_as_uid(ds->discsignr, &sinfo, ds->disc_pid, ds->disc_uid, ds->disc_euid);
		}
	}
}

static int usbfs_notify(struct notifier_block *self, unsigned long action, void *dev)
{
	switch (action) {
	case USB_DEVICE_ADD:
		usbfs_add_device(dev);
		break;
	case USB_DEVICE_REMOVE:
		usbfs_remove_device(dev);
		break;
	case USB_BUS_ADD:
		usbfs_add_bus(dev);
		break;
	case USB_BUS_REMOVE:
		usbfs_remove_bus(dev);
	}

	usbfs_update_special();
	usbfs_conn_disc_event();
	return NOTIFY_OK;
}

static struct notifier_block usbfs_nb = {
	.notifier_call = 	usbfs_notify,
};

/* --------------------------------------------------------------------- */

static struct proc_dir_entry *usbdir = NULL;

int __init usbfs_init(void)
{
	int retval;

	retval = register_filesystem(&usb_fs_type);
	if (retval)
		return retval;

	usb_register_notify(&usbfs_nb);

	/* create mount point for usbfs */
	usbdir = proc_mkdir("usb", proc_bus);

	return 0;
}

void usbfs_cleanup(void)
{
	usb_unregister_notify(&usbfs_nb);
	unregister_filesystem(&usb_fs_type);
	if (usbdir)
		remove_proc_entry("usb", proc_bus);
}