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Commit a8bfd4ab authored by jeff.liu's avatar jeff.liu Committed by Josef Bacik
Browse files

Btrfs: set/change the label of a mounted file system 



With this new ioctl(2) BTRFS_IOC_SET_FSLABEL, we can set/change the label of a mounted file system.

Signed-off-by: default avatarJie Liu <jeff.liu@oracle.com>
Signed-off-by: default avatarAnand Jain <anand.jain@oracle.com>
Reviewed-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Reviewed-by: default avatarGoffredo Baroncelli <kreijack@inwind.it>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
Reviewed-by: default avatarGoffredo Baroncelli <kreijack@inwind.it>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent 867ab667

fs/btrfs/ioctl.c

+42 −0
Original line number Diff line number Diff line
@@ -3936,6 +3936,46 @@ static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg) 
	return ret ? -EFAULT : 0;

}



static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)

{

	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;

	struct btrfs_super_block *super_block = root->fs_info->super_copy;

	struct btrfs_trans_handle *trans;

	char label[BTRFS_LABEL_SIZE];

	int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	if (copy_from_user(label, arg, sizeof(label)))

		return -EFAULT;



	if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) {

		pr_err("btrfs: unable to set label with more than %d bytes\n",

		       BTRFS_LABEL_SIZE - 1);

		return -EINVAL;

	}



	ret = mnt_want_write_file(file);

	if (ret)

		return ret;



	mutex_lock(&root->fs_info->volume_mutex);

	trans = btrfs_start_transaction(root, 0);

	if (IS_ERR(trans)) {

		ret = PTR_ERR(trans);

		goto out_unlock;

	}



	strcpy(super_block->label, label);

	ret = btrfs_end_transaction(trans, root);



out_unlock:

	mutex_unlock(&root->fs_info->volume_mutex);

	mnt_drop_write_file(file);

	return ret;

}



long btrfs_ioctl(struct file *file, unsigned int

		cmd, unsigned long arg)

{
@@ -4038,6 +4078,8 @@ long btrfs_ioctl(struct file *file, unsigned int 
		return btrfs_ioctl_dev_replace(root, argp);

	case BTRFS_IOC_GET_FSLABEL:

		return btrfs_ioctl_get_fslabel(file, argp);

	case BTRFS_IOC_SET_FSLABEL:

		return btrfs_ioctl_set_fslabel(file, argp);

	}



	return -ENOTTY;

include/uapi/linux/btrfs.h

+2 −0
Original line number Diff line number Diff line
@@ -504,6 +504,8 @@ struct btrfs_ioctl_send_args { 
			       struct btrfs_ioctl_qgroup_limit_args)

#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \

				   char[BTRFS_LABEL_SIZE])

#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \

				   char[BTRFS_LABEL_SIZE])

#define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \

				      struct btrfs_ioctl_get_dev_stats)

#define BTRFS_IOC_DEV_REPLACE _IOWR(BTRFS_IOCTL_MAGIC, 53, \