sysfs: clean up sysfs_get_dirent()

The pre-existing sysfs interfaces which take explicit namespace
argument are weird in that they place the optional @ns in front of
@name which is contrary to the established convention.  For example,
we end up forcing vast majority of sysfs_get_dirent() users to do
sysfs_get_dirent(parent, NULL, name), which is silly and error-prone
especially as @ns and @name may be interchanged without causing
compilation warning.

This renames sysfs_get_dirent() to sysfs_get_dirent_ns() and swap the
positions of @name and @ns, and sysfs_get_dirent() is now a wrapper
around sysfs_get_dirent_ns().  This makes confusions a lot less
likely.

There are other interfaces which take @ns before @name.  They'll be
updated by following patches.

This patch doesn't introduce any functional changes.

v2: EXPORT_SYMBOL_GPL() wasn't updated leading to undefined symbol
    error on module builds.  Reported by build test robot.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index c792f73..6695040 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -245,9 +245,9 @@
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
 void sysfs_notify_dirent(struct sysfs_dirent *sd);
-struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
-				      const void *ns,
-				      const unsigned char *name);
+struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
+					 const unsigned char *name,
+					 const void *ns);
 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
 void sysfs_put(struct sysfs_dirent *sd);
 
@@ -422,10 +422,9 @@
 static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
 {
 }
-static inline
-struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
-				      const void *ns,
-				      const unsigned char *name)
+static inline struct sysfs_dirent *
+sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
+		    const void *ns)
 {
 	return NULL;
 }
@@ -462,4 +461,10 @@
 	return sysfs_rename_link_ns(kobj, target, old_name, new_name, NULL);
 }
 
+static inline struct sysfs_dirent *
+sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
+{
+	return sysfs_get_dirent_ns(parent_sd, name, NULL);
+}
+
 #endif /* _SYSFS_H_ */