** Package changed: linux (Ubuntu) => lvm2 (Ubuntu)
** Also affects: ubuntu-z-systems
Importance: Undecided
Status: New
** Changed in: ubuntu-z-systems
Assignee: (unassigned) => Canonical Foundations Team
(canonical-foundations)
** Changed in: ubuntu-z-systems
Importance: Undecided => Critical
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https://bugs.launchpad.net/bugs/1817097
Title:
pvmove causes file system corruption without notice upon move from 512
-> 4096 logical block size devices
Status in Ubuntu on IBM z Systems:
New
Status in lvm2 package in Ubuntu:
New
Bug description:
Problem Description---
Summary
=======
Environment: IBM Z13 LPAR and z/VM Guest
IBM Type: 2964 Model: 701 NC9
OS: Ubuntu 18.10 (GNU/Linux 4.18.0-13-generic s390x)
Package: lvm2 version 2.02.176-4.1ubuntu3
LVM: pvmove operation corrupts file system when using 4096 (4k) logical block
size
and default block size being 512 bytes in the underlying devices
The problem is immediately reproducible.
We see a real usability issue with data destruction as consequence - which is
not acceptable.
We expect 'pvmove' to fail with error in such situations to prevent fs
destruction,
which might possibly be overridden by a force flag.
Details
=======
After a 'pvmove' operation is run to move a physical volume onto an ecrypted
device with 4096 bytes logical block size we experience a file system
corruption.
There is no need for the file system to be mounted, but the problem surfaces
differently if so.
Either, the 'pvs' command after the pvmove shows
/dev/LOOP_VG/LV: read failed after 0 of 1024 at 0: Invalid argument
/dev/LOOP_VG/LV: read failed after 0 of 1024 at 314507264: Invalid argument
/dev/LOOP_VG/LV: read failed after 0 of 1024 at 314564608: Invalid argument
/dev/LOOP_VG/LV: read failed after 0 of 1024 at 4096: Invalid argument
or
a subsequent mount shows (after umount if the fs had previously been mounted
as in our
setup)
mount: /mnt: wrong fs type, bad option, bad superblock on
/dev/mapper/LOOP_VG-LV, missing codepage or helper program, or other error.
A minimal setup of LVM using one volume group with one logical volume defined,
based on one physical volume is sufficient to raise the problem. One more
physical
volume of the same size is needed to run the pvmove operation to.
LV
|
VG: LOOP_VG [ ]
|
PV: /dev/loop0 --> /dev/mapper/enc-loop
( backed by /dev/mapper/enc-loop )
The physical volumes are backed by loopback devices (losetup) to base the
problem report on, but we have seen the error on real SCSI multipath volumes
also, with and without cryptsetup mapper devices in use.
Further discussion
==================
https://www.saout.de/pipermail/dm-crypt/2019-February/006078.html
The problem does not occur on block devices with native size of 4k.
E.g. DASDs, or file systems with mkfs -b 4096 option.
Terminal output
===============
See attached file pvmove-error.txt
Debug data
==========
pvmove was run with -dddddd (maximum debug level)
See attached journal file.
Contact Information = christian.r...@de.ibm.com
---uname output---
Linux system 4.18.0-13-generic #14-Ubuntu SMP Wed Dec 5 09:00:35 UTC 2018
s390x s390x s390x GNU/Linux
Machine Type = IBM Type: 2964 Model: 701 NC9
---Debugger---
A debugger is not configured
---Steps to Reproduce---
1.) Create two image files of 500MB in size
and set up two loopback devices with 'losetup -fP FILE'
2.) Create one physical volume and one volume group 'LOOP_VG',
and one logical volume 'VG'
Run:
pvcreate /dev/loop0
vgcreate LOOP_VG /dev/loop0
lvcreate -L 300MB LOOP_VG -n LV /dev/loop0
3.) Create a file system on the logical volume device:
mkfs.ext4 /dev/mapper/LOOP_VG-LV
4.) mount the file system created in the previous step to some empty
available directory:
mount /dev/mapper/LOOP_VG-LV /mnt
5.) Set up a second physical volume, this time encrypted with LUKS2,
and open the volume to make it available:
cryptsetup luksFormat --type luks2 --sector-size 4096 /dev/loop1
cryptsetup luksOpen /dev/loop1 enc-loop
6.) Create the second physical volume, and add it to the LOOP_VG
pvcreate /dev/mapper/enc-loop
vgextend LOOP_VG /dev/mapper/enc-loop
7.) Ensure the new physical volume is part of the volume group:
pvs
8.) Move the /dev/loop0 volume onto the encrypted volume with maximum debug
option:
pvmove -dddddd /dev/loop0 /dev/mapper/enc-loop
9.) The previous step succeeds, but corrupts the file system on the logical
volume
We expect an error here.
There might be a command line flag to override used because corruption
does not cause a data loss.
Userspace tool common name: pvmove
The userspace tool has the following bit modes: 64bit
Userspace rpm: lvm2 in versoin 2.02.176-4.1ubuntu3
Userspace tool obtained from project website: na
*Additional Instructions for christian.r...@de.ibm.com:
-Attach ltrace and strace of userspace application.
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