[Bug 2044657] Re: zfs block cloning file system corruption

[Chad Wagner]

Reproducible on Ubuntu 22.04 LTS w/ linux-hwe-6.2 (zfs-2.1.9) using the
NixOS test suite:

[zhammer::647] checking 10000 files at iteration 0
[zhammer::647] zhammer_647_0 differed from zhammer_647_576!
[zhammer::647] Hexdump diff follows
--- zhammer_647_0.hex   2023-11-30 15:37:43.887596987 +0000
+++ zhammer_647_576.hex 2023-11-30 15:37:43.891596970 +0000
@@ -1,3 +1,3 @@
-00000000  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  |................|
+00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 *
 00004000
[zhammer::639] checking 10000 files at iteration 0
[zhammer::631] checking 10000 files at iteration 0
[zhammer::635] checking 10000 files at iteration 0
[zhammer::677] checking 10000 files at iteration 0
parallel: This job failed:
./zhammer-min.sh /test 10000000 16k 10000 7

The zhammer script is available at:
https://github.com/numinit/nixpkgs/blob/zhammer/nixos/tests/zhammer.sh

The bootstrap for it is to use a ramdisk backed file:
truncate -s 4G /dev/shm/zfs
zpool create -f -o ashift=12 -O canmount=off -O mountpoint=none -O xattr=sa -O dnodesize=auto -O acltype=posix -O atime=off -O relatime=on tank /dev/shm/zfs
zfs create -o canmount=on -o mountpoint=/test tank/test
parallel --lb --halt-on-error now,fail=1 zhammer /test 10000000 16k 10000 ::: $(seq $(nproc))

-- 
You received this bug notification because you are a member of Ubuntu
Sponsors, which is subscribed to the bug report.
https://bugs.launchpad.net/bugs/2044657

Title:
  zfs block cloning file system corruption

Status in linux-hwe-6.2 package in Ubuntu:
  Confirmed
Status in linux-hwe-6.5 package in Ubuntu:
  Confirmed
Status in zfs-linux package in Ubuntu:
  Confirmed

Bug description:
  OpenZFS 2.2 reportedly has a bug where block cloning might lead to
  file system corruption and data loss. This was fixed in OpenZFS 2.2.1.

  Original bug report: https://github.com/openzfs/zfs/issues/15526

  and 2.2.1 release notes:
  https://github.com/openzfs/zfs/releases/tag/zfs-2.2.1

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.2/+bug/2044657/+subscriptions