selinux: remove unnecessary selinux cred request

task_security_struct was obtained at the beginning of may_create
and selinux_inode_init_security, no need to obtain again.
may_create will be called very frequently when create dir and file.

Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Yang Guo <guoyang2@huawei.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -1833,8 +1833,8 @@ static int may_create(struct inode *dir,
 	if (rc)
 		return rc;
 
-	rc = selinux_determine_inode_label(selinux_cred(current_cred()), dir,
-					   &dentry->d_name, tclass, &newsid);
+	rc = selinux_determine_inode_label(tsec, dir, &dentry->d_name, tclass,
+					   &newsid);
 	if (rc)
 		return rc;
 
@@ -2906,8 +2906,7 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 
 	newsid = tsec->create_sid;
 
-	rc = selinux_determine_inode_label(selinux_cred(current_cred()),
-		dir, qstr,
+	rc = selinux_determine_inode_label(tsec, dir, qstr,
 		inode_mode_to_security_class(inode->i_mode),
 		&newsid);
 	if (rc)