Btrfs: Add a new ioctl to get the label of a mounted file system (867ab667) · Commits · 戴 / test

fs/btrfs/ioctl.c

+21 −0

Original line number	Diff line number	Diff line
		@@ -3917,6 +3917,25 @@ out:
		return ret;
		}

		static int btrfs_ioctl_get_fslabel(struct file file, void __user arg)
		{
		struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
		const char *label = root->fs_info->super_copy->label;
		size_t len = strnlen(label, BTRFS_LABEL_SIZE);
		int ret;

		if (len == BTRFS_LABEL_SIZE) {
		pr_warn("btrfs: label is too long, return the first %zu bytes\n",
		--len);
		}

		mutex_lock(&root->fs_info->volume_mutex);
		ret = copy_to_user(arg, label, len);
		mutex_unlock(&root->fs_info->volume_mutex);

		return ret ? -EFAULT : 0;
		}

		long btrfs_ioctl(struct file *file, unsigned int
		cmd, unsigned long arg)
		{
		@@ -4017,6 +4036,8 @@ long btrfs_ioctl(struct file *file, unsigned int
		return btrfs_ioctl_qgroup_limit(file, argp);
		case BTRFS_IOC_DEV_REPLACE:
		return btrfs_ioctl_dev_replace(root, argp);
		case BTRFS_IOC_GET_FSLABEL:
		return btrfs_ioctl_get_fslabel(file, argp);
		}

		return -ENOTTY;

+2 −0

Original line number	Diff line number	Diff line
		@@ -502,6 +502,8 @@ struct btrfs_ioctl_send_args {
		struct btrfs_ioctl_qgroup_create_args)
		#define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \
		struct btrfs_ioctl_qgroup_limit_args)
		#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
		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, \