[RFC][PATCH 13/13] struct filename ->refcnt doesn't need to be atomic

[Al Viro <viro@zeniv.linux.org.uk>]

... or visible outside of audit, really.  Note that references
held in delayed_filename always have refcount 1, and from the
moment of complete_getname() or equivalent point in getname...()
there is no references to struct filename instance anywhere
that would be visible to other threads.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/namei.c         | 8 ++++----
 include/linux/fs.h | 8 +-------
 kernel/auditsc.c   | 6 ++++++
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index bb306177b8a3..9863cc319181 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -128,7 +128,7 @@
 static inline void initname(struct filename *name)
 {
 	name->aname = NULL;
-	atomic_set(&name->refcnt, 1);
+	name->refcnt = 1;
 }
 
 static struct filename *
@@ -283,13 +283,13 @@ void putname(struct filename *name)
 	if (IS_ERR_OR_NULL(name))
 		return;
 
-	refcnt = atomic_read(&name->refcnt);
+	refcnt = name->refcnt;
 	if (unlikely(refcnt != 1)) {
 		if (WARN_ON_ONCE(!refcnt))
 			return;
 
-		if (!atomic_dec_and_test(&name->refcnt))
-			return;
+		name->refcnt--;
+		return;
 	}
 
 	if (unlikely(name->name != name->iname)) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d57c8e21be13..4ea32aba847b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2835,7 +2835,7 @@ extern struct kobject *fs_kobj;
 struct audit_names;
 struct filename {
 	const char		*name;	/* pointer to actual string */
-	atomic_t		refcnt;
+	int			refcnt;
 	struct audit_names	*aname;
 	const char		iname[];
 };
@@ -2944,12 +2944,6 @@ int delayed_getname_uflags(struct delayed_filename *v, const char __user *, int)
 void dismiss_delayed_filename(struct delayed_filename *);
 struct filename *complete_getname(struct delayed_filename *);
 
-static inline struct filename *refname(struct filename *name)
-{
-	atomic_inc(&name->refcnt);
-	return name;
-}
-
 extern int finish_open(struct file *file, struct dentry *dentry,
 			int (*open)(struct inode *, struct file *));
 extern int finish_no_open(struct file *file, struct dentry *dentry);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index e59a094bb9f7..d71fc73455b2 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2169,6 +2169,12 @@ static struct audit_names *audit_alloc_name(struct audit_context *context,
 	return aname;
 }
 
+static inline struct filename *refname(struct filename *name)
+{
+	name->refcnt++;
+	return name;
+}
+
 /**
  * __audit_getname - add a name to the list
  * @name: name to add
-- 
2.47.3