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>

fs/ocfs2/cluster/masklog.c

@@ -30,7 +30,7 @@
 
 struct mlog_bits mlog_and_bits = MLOG_BITS_RHS(MLOG_INITIAL_AND_MASK);
 EXPORT_SYMBOL_GPL(mlog_and_bits);
-struct mlog_bits mlog_not_bits = MLOG_BITS_RHS(MLOG_INITIAL_NOT_MASK);
+struct mlog_bits mlog_not_bits = MLOG_BITS_RHS(0);
 EXPORT_SYMBOL_GPL(mlog_not_bits);
 
 static ssize_t mlog_mask_show(u64 mask, char *buf)
@@ -80,7 +80,6 @@ struct mlog_attribute {
 }
 
 static struct mlog_attribute mlog_attrs[MLOG_MAX_BITS] = {
-	define_mask(EXIT),
 	define_mask(TCP),
 	define_mask(MSG),
 	define_mask(SOCKET),