diff --git a/fs/locks.c b/fs/locks.c
index 43dbc7f..9a3fe0d 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1119,7 +1119,7 @@
 			 * If we've been sleeping someone might have
 			 * changed the permissions behind our back.
 			 */
-			if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
+			if (__mandatory_lock(inode))
 				continue;
 		}
 
@@ -1761,9 +1761,7 @@
 	/* Don't allow mandatory locks on files that may be memory mapped
 	 * and shared.
 	 */
-	if (IS_MANDLOCK(inode) &&
-	    (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
-	    mapping_writably_mapped(filp->f_mapping)) {
+	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
 		error = -EAGAIN;
 		goto out;
 	}
@@ -1887,9 +1885,7 @@
 	/* Don't allow mandatory locks on files that may be memory mapped
 	 * and shared.
 	 */
-	if (IS_MANDLOCK(inode) &&
-	    (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
-	    mapping_writably_mapped(filp->f_mapping)) {
+	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
 		error = -EAGAIN;
 		goto out;
 	}
@@ -2083,9 +2079,7 @@
 		out += sprintf(out, "%6s %s ",
 			     (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
 			     (inode == NULL) ? "*NOINODE*" :
-			     (IS_MANDLOCK(inode) &&
-			      (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ?
-			     "MANDATORY" : "ADVISORY ");
+			     mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
 	} else if (IS_FLOCK(fl)) {
 		if (fl->fl_type & LOCK_MAND) {
 			out += sprintf(out, "FLOCK  MSNFS     ");
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 3f55970..3c028b9 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2044,7 +2044,7 @@
 io_during_grace_disallowed(struct inode *inode, int flags)
 {
 	return nfs4_in_grace() && (flags & (RD_STATE | WR_STATE))
-		&& MANDATORY_LOCK(inode);
+		&& mandatory_lock(inode);
 }
 
 /*
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 7867151..9152f87 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -65,7 +65,7 @@
  * locks on them because there is no way to know if the accesser has
  * the lock.
  */
-#define IS_ISMNDLK(i)	(S_ISREG((i)->i_mode) && MANDATORY_LOCK(i))
+#define IS_ISMNDLK(i)	(S_ISREG((i)->i_mode) && mandatory_lock(i))
 
 /*
  * This is a cache of readahead params that help us choose the proper
diff --git a/fs/read_write.c b/fs/read_write.c
index 507ddff..124693e 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -205,7 +205,7 @@
 	if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
 		goto Einval;
 
-	if (unlikely(inode->i_flock && MANDATORY_LOCK(inode))) {
+	if (unlikely(inode->i_flock && mandatory_lock(inode))) {
 		int retval = locks_mandatory_area(
 			read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
 			inode, file, pos, count);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 16421f6..f5075e0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1369,12 +1369,25 @@
  * Candidates for mandatory locking have the setgid bit set
  * but no group execute bit -  an otherwise meaningless combination.
  */
-#define MANDATORY_LOCK(inode) \
-	(IS_MANDLOCK(inode) && ((inode)->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
+
+static inline int __mandatory_lock(struct inode *ino)
+{
+	return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID;
+}
+
+/*
+ * ... and these candidates should be on MS_MANDLOCK mounted fs,
+ * otherwise these will be advisory locks
+ */
+
+static inline int mandatory_lock(struct inode *ino)
+{
+	return IS_MANDLOCK(ino) && __mandatory_lock(ino);
+}
 
 static inline int locks_verify_locked(struct inode *inode)
 {
-	if (MANDATORY_LOCK(inode))
+	if (mandatory_lock(inode))
 		return locks_mandatory_locked(inode);
 	return 0;
 }
@@ -1385,7 +1398,7 @@
 				    struct file *filp,
 				    loff_t size)
 {
-	if (inode->i_flock && MANDATORY_LOCK(inode))
+	if (inode->i_flock && mandatory_lock(inode))
 		return locks_mandatory_area(
 			FLOCK_VERIFY_WRITE, inode, filp,
 			size < inode->i_size ? size : inode->i_size,