[GFS2] Move some code inside the log lock

This is the first of five patches for bug #248176:

There were still some critical variables being manipulated outside
the log_lock spinlock.  That usually resulted in a hang.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --cc fs/gfs2/lops.c
Simple merge