From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [PATCH v2 09/14] block: Add an explicit bio flag for bios that own their bvec Date: Fri, 25 May 2012 12:49:14 -0400 Message-ID: <20120525164914.GE3855@redhat.com> References: <1337817771-25038-1-git-send-email-koverstreet@google.com> <1337817771-25038-10-git-send-email-koverstreet@google.com> <4FBE687E.1030605@panasas.com> <20120524213158.GB22664@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120524213158.GB22664-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet Cc: Boaz Harrosh , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, neilb-l3A5Bk7waGM@public.gmane.org, drbd-dev-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org, mpatocka-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, sage-BnTBU8nroG7k1uMJSBkQmQ@public.gmane.org, yehuda-L5o5AL9CYN0tUFlbccrkMA@public.gmane.org List-Id: dm-devel.ids On Thu, May 24, 2012 at 02:31:58PM -0700, Kent Overstreet wrote: > On Thu, May 24, 2012 at 07:57:34PM +0300, Boaz Harrosh wrote: > > How do you insure that the original bio which owns the > > bvec is not freed before the split-out bio. > > > > Perhaps calling code needs to make sure by taking an extra > > ref on the original bio, or something. If so a big fat comment > > at bio_split is do. > > Yeah, just added that. > > > > > And I understand you did not like my suggestion of negating > > the meaning of the flag, so the default is zero? > > Please say why? > > I liked it at first, but I think I prefer having the flag be set > if bio_free() must take some action; i.e. you set the flag when you > allocate bi_io_vec. Also, I think bio_alloc_bioset() getting > reimplemented is less likely than people open coding bio splitting or > something that shares bi_io_vec in the future, so it's slightlry less > likely to be used wrong this way. Even if you keep it as it is, I thought BIO_OWNS_BVEC probably communicates the idea better than BIO_HAS_BVEC. Thanks Vivek From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from zimbra.linbit.com (zimbra.linbit.com [212.69.161.123]) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTP id 061D01019A78 for ; Fri, 25 May 2012 22:29:55 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zimbra.linbit.com (Postfix) with ESMTP id E91581B4315 for ; Fri, 25 May 2012 22:29:54 +0200 (CEST) Received: from zimbra.linbit.com ([127.0.0.1]) by localhost (zimbra.linbit.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id kz-6Tf8UlBuB for ; Fri, 25 May 2012 22:29:54 +0200 (CEST) Received: from soda.linbit (tuerlsteher.linbit.com [86.59.100.100]) by zimbra.linbit.com (Postfix) with ESMTP id C42001B40F5 for ; Fri, 25 May 2012 22:29:54 +0200 (CEST) Resent-Message-ID: <20120525202954.GA1903@soda.linbit> Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTP id 4B2331019A78 for ; Fri, 25 May 2012 18:49:26 +0200 (CEST) Date: Fri, 25 May 2012 12:49:14 -0400 From: Vivek Goyal To: Kent Overstreet Message-ID: <20120525164914.GE3855@redhat.com> References: <1337817771-25038-1-git-send-email-koverstreet@google.com> <1337817771-25038-10-git-send-email-koverstreet@google.com> <4FBE687E.1030605@panasas.com> <20120524213158.GB22664@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120524213158.GB22664@google.com> Cc: axboe@kernel.dk, yehuda@hq.newdream.net, dm-devel@redhat.com, neilb@suse.de, linux-kernel@vger.kernel.org, tj@kernel.org, linux-bcache@vger.kernel.org, mpatocka@redhat.com, Boaz Harrosh , linux-fsdevel@vger.kernel.org, sage@newdream.net, agk@redhat.com, drbd-dev@lists.linbit.com Subject: Re: [Drbd-dev] [PATCH v2 09/14] block: Add an explicit bio flag for bios that own their bvec List-Id: Coordination of development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, May 24, 2012 at 02:31:58PM -0700, Kent Overstreet wrote: > On Thu, May 24, 2012 at 07:57:34PM +0300, Boaz Harrosh wrote: > > How do you insure that the original bio which owns the > > bvec is not freed before the split-out bio. > > > > Perhaps calling code needs to make sure by taking an extra > > ref on the original bio, or something. If so a big fat comment > > at bio_split is do. > > Yeah, just added that. > > > > > And I understand you did not like my suggestion of negating > > the meaning of the flag, so the default is zero? > > Please say why? > > I liked it at first, but I think I prefer having the flag be set > if bio_free() must take some action; i.e. you set the flag when you > allocate bi_io_vec. Also, I think bio_alloc_bioset() getting > reimplemented is less likely than people open coding bio splitting or > something that shares bi_io_vec in the future, so it's slightlry less > likely to be used wrong this way. Even if you keep it as it is, I thought BIO_OWNS_BVEC probably communicates the idea better than BIO_HAS_BVEC. Thanks Vivek From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756393Ab2EYQte (ORCPT ); Fri, 25 May 2012 12:49:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46093 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755483Ab2EYQtb (ORCPT ); Fri, 25 May 2012 12:49:31 -0400 Date: Fri, 25 May 2012 12:49:14 -0400 From: Vivek Goyal To: Kent Overstreet Cc: Boaz Harrosh , linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-fsdevel@vger.kernel.org, tj@kernel.org, axboe@kernel.dk, agk@redhat.com, neilb@suse.de, drbd-dev@lists.linbit.com, mpatocka@redhat.com, sage@newdream.net, yehuda@hq.newdream.net Subject: Re: [PATCH v2 09/14] block: Add an explicit bio flag for bios that own their bvec Message-ID: <20120525164914.GE3855@redhat.com> References: <1337817771-25038-1-git-send-email-koverstreet@google.com> <1337817771-25038-10-git-send-email-koverstreet@google.com> <4FBE687E.1030605@panasas.com> <20120524213158.GB22664@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120524213158.GB22664@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 24, 2012 at 02:31:58PM -0700, Kent Overstreet wrote: > On Thu, May 24, 2012 at 07:57:34PM +0300, Boaz Harrosh wrote: > > How do you insure that the original bio which owns the > > bvec is not freed before the split-out bio. > > > > Perhaps calling code needs to make sure by taking an extra > > ref on the original bio, or something. If so a big fat comment > > at bio_split is do. > > Yeah, just added that. > > > > > And I understand you did not like my suggestion of negating > > the meaning of the flag, so the default is zero? > > Please say why? > > I liked it at first, but I think I prefer having the flag be set > if bio_free() must take some action; i.e. you set the flag when you > allocate bi_io_vec. Also, I think bio_alloc_bioset() getting > reimplemented is less likely than people open coding bio splitting or > something that shares bi_io_vec in the future, so it's slightlry less > likely to be used wrong this way. Even if you keep it as it is, I thought BIO_OWNS_BVEC probably communicates the idea better than BIO_HAS_BVEC. Thanks Vivek