On Wed, Aug 30, 2017 at 09:39:39PM +0300, Amir Goldstein wrote:

On Wed, Aug 30, 2017 at 6:23 PM, Josef Bacik [off-list ref] wrote:

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On Wed, Aug 30, 2017 at 06:04:26PM +0300, Amir Goldstein wrote:

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Sorry noise xfs list, I meant to CC fsdevel

On Wed, Aug 30, 2017 at 5:51 PM, Amir Goldstein [off-list ref] wrote:

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Hi all,

This is the 2nd revision of crash consistency patch set.
The main thing that changed since v1 is my confidence in the failures
reported by the test, along with some more debugging options for
running the test tools.

I've collected these patches that have been sitting in Josef Bacik's
tree for a few years and kicked them a bit into shape.
The dm-log-writes target has been merged to kernel v4.1, see:
https://github.com/torvalds/linux/blob/master/Documentation/device-mapper/log-writes.txt

For this posting, I kept the random seeds constant for the test.
I set these constant seeds after running with random seed for a little
while and getting failure reports. With the current values in the test
I was able to reproduce at high probablity failures with xfs, ext4 and btrfs.
The probablity of reproducing the failure is higher on a spinning disk.

I'd rather we make it as evil as possible.  As long as we're printing out the
seed that was used in the output then we can go in and manually change the test
to use the same seed over and over again if we need to debug a problem.

Yeh that's what I did, but then I found values that reproduce a problem,
so maybe its worth clinging on to these values now until the bugs are fixed in
upstream and then as regression tests.

Anyway, I can keep these presets commented out, or run the test twice,
once with presets and once with random seed, whatever Eryu decides.

My thought on this with first glance is using random seed, if a specific
seed reproduce something, maybe another targeted regression test can be
added, as what you did for that ext4 corruption?

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There is an outstanding problem with the test - when I run it with
kvm-xfstests, the test halts and I get soft lockup of log_writes_kthread.
I suppose its a bug in dm-log-writes with some kernel config or with virtio
I wasn't able to determine the reason and have little time to debug this.

Since dm-log-writes is anyway in upstream kernel, I don't think a bug
in dm-log-writes for a certain config is a reason to block this xfstest
from being merged.
Anyway, I would be glad if someone could take a look at the soft lockup
issue. Josef?

Yeah can you give this a try and see if the soft lockup goes away?

It does go away. Thanks!
Now something's wrong with the log.
it get corrupted in most of the test runs, something like this:

replaying 17624@158946: sector 8651296, size 4096, flags 0
replaying 17625@158955: sector 0, size 0, flags 0
replaying 17626@158956: sector 72057596591815616, size 103079215104, flags 0
Error allocating buffer 103079215104 entry 17626

I'll look into it

Amir.

The first 6 patches are all prepare work and seem fine, so I probably
will push them out this week. But I may need more time to look into all
these log-writes dm target and fsx changes.

But seems that there're still problems not sorted out (e.g. this
log-write bug), I'd prefer, when they get merged, removing the auto
group for now until things settle down a bit.

Thanks,
Eryu