[Date Prev][Date Next] [Thread Prev][Thread Next] [Thread Index] [Date Index] [Author Index]

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

From: Jan Kara <jack suse cz>
To: Tejun Heo <tj kernel org>
Cc: jeremy goop org, Jan Kara <jack suse cz>, snitzer redhat com, mst redhat com, linux-ide vger kernel org, dm-devel redhat com, James Bottomley suse de, konishi ryusuke lab ntt co jp, Christoph Hellwig <hch lst de>, k-ueda ct jp nec com, vst vlnb net, linux-scsi vger kernel org, Christoph Hellwig <hch infradead org>, Jeff Moyer <jmoyer redhat com>, rusty rustcorp com au, linux-raid vger kernel org, swhiteho redhat com, chris mason oracle com, tytso mit edu, jaxboe fusionio com, linux-kernel vger kernel org, linux-fsdevel vger kernel org, rwheeler redhat com
Subject: Re: [dm-devel] [PATCH 26/30] ext4: do not send discards as barriers
Date: Fri, 10 Sep 2010 00:53:13 +0200

On Tue 31-08-10 10:11:34, Tejun Heo wrote:
> 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.
  I've tested that when mounting with barrier=0 option inside KVM, this indeed
does destroy the filesystem rather badly. With the barrier option, ext4 has
already survived several crash cycles while running fsstress with
journal_async_commit option. So the patch seems to work as expected.

									Honza
-- 
Jan Kara <jack suse cz>
SUSE Labs, CR

[Date Prev][Date Next] [Thread Prev][Thread Next] [Thread Index] [Date Index] [Author Index]