[dm-devel] [PATCH] dm-log-writes: invalidate the bdev's for both of our devices

[Amir Goldstein]

On Tue, Nov 28, 2017 at 9:29 PM, Amir Goldstein <amir73il at gmail.com> wrote:
> On Tue, Nov 28, 2017 at 7:30 PM, Josef Bacik <josef at toxicpanda.com> wrote:
>> From: Josef Bacik <jbacik at fb.com>
>>
>> Amir noticed that sometimes the xfstests using dm-log-writes would fail
>> randomly but would work fine after trying again manually.  This is
>> because dm-log-writes writes directly to the device, but the log replay
>> tools read and write via the block device page cache.  Sometimes this
>> resulted in stale data being in the block device's page cache which
>> would result in random failures.  To handle this simply invalidate the
>> block device page cache on destruction so any replay of the log device
>> that follows will be forced to read the new real contents.
>>
>> Reported-and-tested-by: Amir Goldstein <amir73il at gmail.com>
>
> I'm fine with the Reported-by, but let's wait a while with this patch so
> I have more time to torture it.
> The incidents I got even before the patch did not happen more than
> a handful of times after running for a few days, so I need some more
> days to validate the fix.
> I had already sent you some weird output. Let's see what else comes
> along.
>

Sorry, no cigar.
Another run just completed with Malformed log and corrupted fs

The _check_scratch_fs that fails is the one right after _log_writes_remove
just like the report that I sent before this patch
and the LOGWRITES_DEV itself has malformed entry before the "end" mark
or even the last fsync mark:

./src/log-writes/replay-log -v --log $LOGWRITES_DEV --find --end-mark
testfile1.mark17
Malformed entry @112134

For what its worth, I am testing on spinning disks, 100G scratch dev.
Right now, I zoomed in on the following fsx seeds that managed to fail the test
a few times already, but in different ways, so I'm not sure the seeds are more
than voodoo:
seeds=(4597 4598 4599 4600)

I'll start running the same test but with fsx running on test partition, just
to get the feel for running the same fsx threads on bare xfs.

Any other ideas?

Amir.
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