[GFS2] lockdump improvements

The patch below consists of the following changes (in code order):

1. I fixed a minor compiler warning regarding the printing of
   a kernel symbol address.
2. I implemented a suggestion from Dave Teigland that moves
   the debugfs information for gfs2 into a subdirectory so
   we can easily expand our use of debugfs in the future.
   The current code keeps the glock information in:
   /debug/gfs2/<fs>
   With the patch, the new code keeps the glock information in:
   /debug/gfs2/<fs>/glock
   That will allow us to create more debugfs files in the future.
3. This fixes a bug whereby a failed mount attempt causes the
   debugfs file to not be deleted.  Failed mount attempts should
   always clean up after themselves, including deleting the
   debugfs file and/or directory.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index fdf0470..d995441 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -609,7 +609,8 @@
 
 	unsigned long sd_last_warning;
 	struct vfsmount *sd_gfs2mnt;
-	struct dentry *debugfs_dentry; /* for debugfs */
+	struct dentry *debugfs_dir;    /* debugfs directory */
+	struct dentry *debugfs_dentry_glocks; /* for debugfs */
 };
 
 #endif /* __INCORE_DOT_H__ */