* A question on umounting without flushing journal
@ 2020-03-03 10:26 Bo Branten
2020-03-03 17:30 ` Theodore Y. Ts'o
0 siblings, 1 reply; 2+ messages in thread
From: Bo Branten @ 2020-03-03 10:26 UTC (permalink / raw)
To: linux-ext4
Hello,
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?
Bo Branten
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: A question on umounting without flushing journal
2020-03-03 10:26 A question on umounting without flushing journal Bo Branten
@ 2020-03-03 17:30 ` Theodore Y. Ts'o
0 siblings, 0 replies; 2+ messages in thread
From: Theodore Y. Ts'o @ 2020-03-03 17:30 UTC (permalink / raw)
To: Bo Branten; +Cc: linux-ext4
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
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2020-03-03 10:26 A question on umounting without flushing journal Bo Branten
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