xfs_scrub: actually try to fix summary counters ahead of repairs

xfs_scrub: actually try to fix summary counters ahead of repairs

A while ago, I decided to make phase 4 check the summary counters before
it starts any other repairs, having observed that repairs of primary
metadata can fail because the summary counters (incorrectly) claim that
there aren't enough free resources in the filesystem.  However, if
problems are found in the summary counters, the repair work will be run
as part of the AG 0 repairs, which means that it runs concurrently with
other scrubbers.  This doesn't quite get us to the intended goal, so try
to fix the scrubbers ahead of time.  If that fails, tough, we'll get
back to it in phase 7 if scrub gets that far.

Fixes: cbaf1c9d91a0 ("xfs_scrub: check summary counters")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>