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/aops.c b/fs/ocfs2/aops.c
index 5dbfc9e..9551518 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -123,7 +123,6 @@
 bail:
 	brelse(bh);
 
-	mlog_exit(err);
 	return err;
 }
 
@@ -208,7 +207,6 @@
 	if (err < 0)
 		err = -EIO;
 
-	mlog_exit(err);
 	return err;
 }
 
@@ -323,7 +321,6 @@
 out:
 	if (unlock)
 		unlock_page(page);
-	mlog_exit(ret);
 	return ret;
 }
 
@@ -402,8 +399,6 @@
 
 	ret = block_write_full_page(page, ocfs2_get_block, wbc);
 
-	mlog_exit(ret);
-
 	return ret;
 }
 
@@ -484,8 +479,6 @@
 bail:
 	status = err ? 0 : p_blkno;
 
-	mlog_exit((int)status);
-
 	return status;
 }
 
@@ -616,7 +609,6 @@
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
-	int ret;
 
 	/*
 	 * Fallback to buffered I/O if we see an inode without
@@ -629,13 +621,10 @@
 	if (i_size_read(inode) <= offset)
 		return 0;
 
-	ret = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev,
-				   iov, offset, nr_segs,
-				   ocfs2_direct_IO_get_blocks,
-				   ocfs2_dio_end_io, NULL, 0);
-
-	mlog_exit(ret);
-	return ret;
+	return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev,
+				    iov, offset, nr_segs,
+				    ocfs2_direct_IO_get_blocks,
+				    ocfs2_dio_end_io, NULL, 0);
 }
 
 static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,