ocfs2: Remove EXIT from masklog.

mlog_exit is used to record the exit status of a function.
But because it is added in so many functions, if we enable it,
the system logs get filled up quickly and cause too much I/O.
So actually no one can open it for a production system or even
for a test.

This patch just try to remove it or change it. So:
1. if all the error paths already use mlog_errno, it is just removed.
   Otherwise, it will be replaced by mlog_errno.
2. if it is used to print some return value, it is replaced with
   mlog(0,...).
mlog_exit_ptr is changed to mlog(0.
All those mlog(0,...) will be replaced with trace events later.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
diff --git a/fs/ocfs2/symlink.c b/fs/ocfs2/symlink.c
index 8a81688..5485b19 100644
--- a/fs/ocfs2/symlink.c
+++ b/fs/ocfs2/symlink.c
@@ -72,7 +72,6 @@
 	fe = (struct ocfs2_dinode *) (*bh)->b_data;
 	link = (char *) fe->id2.i_symlink;
 bail:
-	mlog_exit(status);
 
 	return link;
 }
@@ -100,7 +99,8 @@
 
 	brelse(bh);
 out:
-	mlog_exit(ret);
+	if (ret < 0)
+		mlog_errno(ret);
 	return ret;
 }
 
@@ -136,7 +136,8 @@
 	nd_set_link(nd, status ? ERR_PTR(status) : link);
 	brelse(bh);
 
-	mlog_exit(status);
+	if (status)
+		mlog_errno(status);
 	return NULL;
 }