Re: [dm-devel] [PATCH 26/30] ext4: do not send discards as barriers

[Tejun Heo <tj kernel org>]

On 08/30/2010 10:20 PM, Jan Kara wrote:
>   My setup is that I have a dedicated partition / drive for a filesystem
> which is written to from a guest kernel running under KVM. I have set it up
> using virtio driver with cache=writeback so that the host caches the writes
> in a similar way disk caches them. At some point I just kill the qemu-kvm
> process and at that point I'd like to also throw away data cached by the
> host...

$ echo 1 > /sys/block/sdX/device/delete
$ echo - - - > /sys/class/scsi_host/hostX/scan

should do the trick.

Thanks.

-- 
tejun