From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424681AbcFMPqS (ORCPT ); Mon, 13 Jun 2016 11:46:18 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:42167 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423745AbcFMPqQ (ORCPT ); Mon, 13 Jun 2016 11:46:16 -0400 Date: Mon, 13 Jun 2016 08:46:14 -0700 From: Christoph Hellwig To: Hannes Reinecke Cc: Ming Lei , Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Christoph Hellwig , Kent Overstreet , "4.3+" , Shaohua Li , Jens Axboe Subject: Re: [PATCH v2] block: make sure big bio is splitted into at most 256 bvecs Message-ID: <20160613154614.GC23990@infradead.org> References: <1465556858-30949-1-git-send-email-ming.lei@canonical.com> <575AA66D.5010407@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <575AA66D.5010407@suse.de> User-Agent: Mutt/1.5.24 (2015-08-30) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 10, 2016 at 01:37:17PM +0200, Hannes Reinecke wrote: > Hmm. So everybody is suffering because someone _might_ be using bio_clone? > Why can't we fixup bio_clone() (or the callers of which) to correctly > set the queue limits? The only one suffering is bcache. Everyone else uses bios below the block layer arbitrary max size. The fixup to allow bio_clone support a larger size is the same one as to allow everyone else submitting larger bios: increase BIO_MAX_PAGES and create the required mempools to back that new larger size. Or just go for multipage biovecs..