xfs_repair: don't crash on -vv

A user reported a crash in xfs_repair when they run it with -vv
specified on the command line.  Ultimately this harks back to xfs_m in
main() containing uninitialized stack contents, and inadequate null
checks.  Fix both problems in one go.

Reported-by: Santiago Kraus <santiago_kraus@yahoo.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2 files changed