From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Bo Branten <bosse@acc.umu.se>
Cc: linux-ext4@vger.kernel.org
Subject: Re: A question on umounting without flushing journal
Date: Tue, 3 Mar 2020 12:30:38 -0500 [thread overview]
Message-ID: <20200303173038.GC61444@mit.edu> (raw)
In-Reply-To: <alpine.DEB.2.21.2003031120390.949380@stalin.acc.umu.se>
On Tue, Mar 03, 2020 at 11:26:13AM +0100, Bo Branten wrote:
>
> now I have another question on how to test the ext4 driver we implement for
> another os: At mount time the driver should check the journal and use jbd2
> to replay if there is anything left in it and I would like to ask if there
> is any other methods to do an unclean umount in linux besides pressing
> reset? I would like to leave a lot of records in the journal that our driver
> can try to process?
The standard way to do this in xfstests is using the dm-flakey
device-mapper device. We set it up so that all reads and writes are
passed through, and then we start some workload such as fsstress, and
then we reconfigure dm-flakey to drop 100% of all write requests to
the underlying block device.
We then kill the workload, and unmount the file system, and then we
reset the dm-flakey device to pass through 100% of all writes. This
simulates quite accurately what the block device would look like after
a sudden power failure, but it doesn't require a power-fail rack
(without shortening the lives of the equipment; dropping power tends
to put a lot stress on the hardware).
Cheers,
- Ted
prev parent reply other threads:[~2020-03-03 17:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 10:26 A question on umounting without flushing journal Bo Branten
2020-03-03 17:30 ` Theodore Y. Ts'o [this message]
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