Re: [PATCH] tests/xfs: test for log recovery failure after tail overwrite

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Fri, Jun 30, 2017 at 11:44:05AM +0800, Eryu Guan wrote:
> Hi Brian,
> 
> On Fri, Jun 16, 2017 at 12:46:19PM -0400, Brian Foster wrote:
> > XFS is susceptible to log recovery problems if the fs crashes under
> > certain circumstances. If the tail has been pinned for long enough
> > to the log to fill and the next batch of log buffer submissions
> > happen to fail, the filesystem shutsdown having potentially
> > overwritten part of the range between the last good tail->head range
> > in the log. This causes log recovery to fail with crc mismatch or
> > invalid log record errors.
> > 
> > This problem is not yet fixed and thus known/expected to fail. At
> > this time, this test serves as a reminder that the problem exists
> > and a reproducer for future verification purposes. Note that this
> > problem is currently only reproducible with larger (non-default) log
> > buffer sizes (i.e., '-o logbsize=256k') or smaller block sizes (1k).
> > 
> > Signed-off-by: Brian Foster <bfoster@redhat.com>
> > ---
> > 
> > Hi all,
> > 
> > This patch uses the XFS debug kernel mechanism recently posted for
> > review[1] to reproduce an XFS log recovery problem. Note that this test
> > depends on the aforementioned patch and thus should not be merged
> > until/unless the corresponding kernel patch is merged.
> 
> Any decision made on the kernel side patch? Sorry, I'm a bit lost on the
> kernel side discussions.

Uhhhh, I think this test is being redone to work with the new xfs
errortag mechanism that'll be appearing soon.  I will send patches
to fix up xfstests momentarily.

--D

> 
> Thanks,
> Eryu
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