CRED: Wrap task credential accesses in the JFFS2 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>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

fs/jffs2/fs.c

@@ -442,14 +442,14 @@ struct inode *jffs2_new_inode (struct inode *dir_i, int mode, struct jffs2_raw_i
 
 	memset(ri, 0, sizeof(*ri));
 	/* Set OS-specific defaults for new inodes */
-	ri->uid = cpu_to_je16(current->fsuid);
+	ri->uid = cpu_to_je16(current_fsuid());
 
 	if (dir_i->i_mode & S_ISGID) {
 		ri->gid = cpu_to_je16(dir_i->i_gid);
 		if (S_ISDIR(mode))
 			mode |= S_ISGID;
 	} else {
-		ri->gid = cpu_to_je16(current->fsgid);
+		ri->gid = cpu_to_je16(current_fsgid());
 	}
 
 	/* POSIX ACLs have to be processed now, at least partly.