Pavol pointed out that there is one silent error case in the mount
path, and that others are rather uninformative.
I've taken Pavol's suggested patch and extended it a bit to also:
* fix a message which says "turned off" but actually errors out
* consolidate the vaguely differentiated "SB sanity check [12]"
messages, and hexdump the superblock for analysis
Original-patch-by: Pavol Gono <Pavol.Gono@siemens.com> Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Alex Elder <aelder@sgi.com>