From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F42EC43610 for ; Tue, 20 Nov 2018 09:39:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E44E820831 for ; Tue, 20 Nov 2018 09:39:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mWkcNA7P" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E44E820831 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726172AbeKTUHT (ORCPT ); Tue, 20 Nov 2018 15:07:19 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:58078 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726119AbeKTUHT (ORCPT ); Tue, 20 Nov 2018 15:07:19 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=/1QD8IHz4s0ToviMsZ6K1bGk6araZkuLZ8xYzy8hZQM=; b=mWkcNA7PkKY598UVGlXbNHh/x YJH9PIDOJaf+FcDyvN3s0MSOqVCCRMvPnepG+ik/JBgvh3mmCckwvpvCvcaFGikJcUWdiCChFd/ZX U0Z7ueLiTS4o8SUb+b/mXLXDzMcBsirjcA6DzaCh73LbF+7vC3jTZp/6Bs9ltJwEvWMY+++3XHtDh UtGAC2UhoJnP8lQyaQNoI4PItIL74NJN+kdhWx0TfVkMUtwtCR0Cxrj1C3nnqYBNlN/ksfprWbAVI HrBk315ueWshOLfpArruExwgqPzwkVwO0ChizzMkfM3hsexLurKOc1b3d93Jum7OqCk5QJ9HB0kZB U0D0wTZnw==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gP2Ut-0000Ox-QW; Tue, 20 Nov 2018 09:39:07 +0000 Date: Tue, 20 Nov 2018 01:39:07 -0800 From: Christoph Hellwig To: Damien Le Moal Cc: "linux-block@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "dm-devel@redhat.com" Subject: Re: RFC: REQ_PRIO use Message-ID: <20181120093907.GA32682@infradead.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org We have two places that check the flag, the writeback tracking code: block/blk-wbt.c:#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO) block/blk-wbt.c: if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd()) and bcache: drivers/md/bcache/request.c: !(bio->bi_opf & REQ_PRIO)) drivers/md/bcache/request.c: !(bio->bi_opf & REQ_PRIO) && the original idea was that not all I/O is a priority we should not blindly boost priority for metadata. Of course wbt actually ignores and it and we may just give in and just check REQ_META, except for the fact that f2fs now actually submits REQ_PRIO requests without REQ_META..