On Tue, Nov 26, 2019 at 09:24:48AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=205655
> 
>             Bug ID: 205655
>            Summary: kvm with cache=none and btrfs -> corrupted file system
>            Product: Virtualization
>            Version: unspecified
>     Kernel Version: 4.9   4.19    5.3.12
>           Hardware: x86-64
>                 OS: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: high
>           Priority: P1
>          Component: kvm
>           Assignee: virtualization_kvm@kernel-bugs.osdl.org
>           Reporter: denis.ovsyannikov@gmail.com
>         Regression: No
> 
> hello
> we use kvm with disks formatted in btrfs
> when we turned on the mode "cache=none"
> got data corruption
> other modes work well
> 
> we tested it on three servers and the result is always repeated
> we tested on three operating systems(debian 9, debian 10, manjaro with kernel
> 5.3.12)
> 
> fstab
> UUID=a49494f2-35a4-4a9c-aab0-1afc905c02c2 /mnt/test      btrfs   defaults 0 2
> 
> dmesg
> [675174.887900] BTRFS error (device sde1): bdev /dev/sde1 errs: wr 0, rd 0,
> flush 0, corrupt 2137, gen 0
> 
> [102857.086874] BTRFS warning (device sdc1): csum failed root 256 ino 260 off
> 1735843840 csum 0xf69f8dd2 expected csum 0x96e71981 mirror 1

Please post your QEMU command-line.

What is the storage configuration on the host?  Which host file system
are you using?  Which image file format?

What test is being run inside the guest?

Is this a regression?  Which host and guest kernel versions worked fine
before?