CRED: Wrap task credential accesses in the SMBFS filesystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

fs/smbfs/dir.c

@@ -667,8 +667,8 @@ smb_make_node(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 
 	attr.ia_valid = ATTR_MODE | ATTR_UID | ATTR_GID;
 	attr.ia_mode = mode;
-	attr.ia_uid = current->euid;
-	attr.ia_gid = current->egid;
+	attr.ia_uid = current_euid();
+	attr.ia_gid = current_egid();
 
 	if (!new_valid_dev(dev))
 		return -EINVAL;

fs/smbfs/inode.c

@@ -586,7 +586,7 @@ static int smb_fill_super(struct super_block *sb, void *raw_data, int silent)
 		if (parse_options(mnt, raw_data))
 			goto out_bad_option;
 	}
-	mnt->mounted_uid = current->uid;
+	mnt->mounted_uid = current_uid();
 	smb_setcodepage(server, &mnt->codepage);
 
 	/*

fs/smbfs/proc.c

@@ -864,7 +864,7 @@ smb_newconn(struct smb_sb_info *server, struct smb_conn_opt *opt)
 		goto out;
 
 	error = -EACCES;
-	if (current->uid != server->mnt->mounted_uid && 
+	if (current_uid() != server->mnt->mounted_uid &&
 	    !capable(CAP_SYS_ADMIN))
 		goto out;