[GFS2] Use mutices rather than semaphores

As well as a number of minor bug fixes, this patch changes GFS
to use mutices rather than semaphores. This results in better
information in case there are any locking problems.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index 75e9a32..c598435 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -41,9 +41,9 @@
 {
 	unsigned int count;
 
-	down(&sdp->sd_freeze_lock);
+	mutex_lock(&sdp->sd_freeze_lock);
 	count = sdp->sd_freeze_count;
-	up(&sdp->sd_freeze_lock);
+	mutex_unlock(&sdp->sd_freeze_lock);
 
 	return sprintf(buf, "%u\n", count);
 }