df reports negative number of used blocks on large filesystem

[Thomas Dreibholz]

df reports negative number of used blocks on large filesystem (18.5 TiB):

nornetpp@oesthorn:~$ df /home
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb1 2684353464 -1825532684 4509886148 - /home

nornetpp@oesthorn:~$ cat /etc/fstab | grep /home
UUID=9a12de8d-1d01-4930-9897-5d4097b7f892 /home reiserfs defaults

nornetpp@oesthorn:~$ sudo gdisk /dev/sdb
[sudo] password for nornetpp:
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): p
Disk /dev/sdb: 39728447488 sectors, 18.5 TiB
Model: Virtual disk
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 0956159A-AAFE-4DB4-8FD3-6F6A515B1727
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 39728447454
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)

Number Start (sector) End (sector) Size Code Name
   1 2048 39728447454 18.5 TiB 8300 Linux filesystem

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: coreutils 8.30-3ubuntu2
ProcVersionSignature: Ubuntu 5.8.0-41.46~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-41-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
Date: Wed Feb 3 12:35:45 2021
InstallationDate: Installed on 2012-10-12 (3036 days ago)
InstallationMedia: Ubuntu-Server 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120817.3)
SourcePackage: coreutils
UpgradeStatus: Upgraded to focal on 2021-02-03 (0 days ago)