ntfs3: add FS_IOC_GETFSLABEL ioctl

Add support for the FS_IOC_GETFSLABEL ioctl.

Signed-off-by: Ethan Ferguson <ethan.ferguson@zetier.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/file.c

@@ -49,6 +49,14 @@ static int ntfs_ioctl_fitrim(struct ntfs_sb_info *sbi, unsigned long arg)
 	return 0;
 }
 
+static int ntfs_ioctl_get_volume_label(struct ntfs_sb_info *sbi, u8 __user *buf)
+{
+	if (copy_to_user(buf, sbi->volume.label, FSLABEL_MAX))
+		return -EFAULT;
+
+	return 0;
+}
+
 /*
  * ntfs_ioctl - file_operations::unlocked_ioctl
  */
@@ -64,6 +72,8 @@ long ntfs_ioctl(struct file *filp, u32 cmd, unsigned long arg)
 	switch (cmd) {
 	case FITRIM:
 		return ntfs_ioctl_fitrim(sbi, arg);
+	case FS_IOC_GETFSLABEL:
+		return ntfs_ioctl_get_volume_label(sbi, (u8 __user *)arg);
 	}
 	return -ENOTTY; /* Inappropriate ioctl for device. */
 }