misc: fix undo file setup

Fix Coverity bugs 1297094-1297101 by fixing all the mutations in the
*_setup_tdb() functions, fixing buffer overflows, and checking
return values.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
6 files changed