From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751772AbbEZXDY (ORCPT ); Tue, 26 May 2015 19:03:24 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53967 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078AbbEZXDU (ORCPT ); Tue, 26 May 2015 19:03:20 -0400 Date: Wed, 27 May 2015 09:03:09 +1000 From: NeilBrown To: Ming Lin Cc: Christoph Hellwig , lkml , Kent Overstreet , Jens Axboe , Dongsu Park , linux-raid@vger.kernel.org Subject: Re: [PATCH v4 06/11] md/raid5: get rid of bio_fits_rdev() Message-ID: <20150527090309.2cddf33b@notabene.brown> In-Reply-To: References: <1432318723-18829-1-git-send-email-mlin@kernel.org> <1432318723-18829-7-git-send-email-mlin@kernel.org> <20150525154829.4330f149@notabene.brown> <20150525175414.6a1fc33d@notabene.brown> <20150525141708.GA26249@lst.de> X-Mailer: Claws Mail 3.10.1-162-g4d0ed6 (GTK+ 2.24.25; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/8MMpc4P+nLG6sfy3WjHJiEp"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/8MMpc4P+nLG6sfy3WjHJiEp Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Tue, 26 May 2015 15:32:38 -0700 Ming Lin wrote: > On Tue, May 26, 2015 at 7:33 AM, Ming Lin wrote: > > On Mon, May 25, 2015 at 7:17 AM, Christoph Hellwig wrote: > >> On Mon, May 25, 2015 at 05:54:14PM +1000, NeilBrown wrote: > >>> Did I write that? I guess I did :-( > >>> I meant *after*. Don't get rid of bio_fits_rdev until split_bio is = in > >>> chunk_aligned_read(). > >> > >> I suspect the whole series could use some reordering. > > > > Nice reordering. > > I'll do this. >=20 > Here is the reordering. > https://git.kernel.org/cgit/linux/kernel/git/mlin/linux.git/log/?h=3Dbloc= k-generic-req >=20 > I'll post it if you are OK. >=20 > [PATCH 01/15] block: add blk_queue_split() > [PATCH 02/15] md: remove ->merge_bvec_fn > [PATCH 03/15] dm: remov merge functions > [PATCH 04/15] drbd: remove ->merge_bvec_fn > [PATCH 05/15] pktcdvd: remove ->merge_bvec_fn > [PATCH 06/15] rbd: remove ->merge_bvec_fn > [PATCH 07/15] bcache: remove driver private bio splitting code > [PATCH 08/15] btrfs: remove bio splitting and merge_bvec_fn() calls > [PATCH 09/15] block: call blk_queue_split() in make_request functions > [PATCH 10/15] block: kill ->merge_bvec_fn and simplify bio_add_page > [PATCH 11/15] block: remove split code in blkdev_issue_discard > [PATCH 12/15] md/raid5: get rid of bio_fits_rdev() > [PATCH 13/15] block: remove bio_get_nr_vecs() > [PATCH 14/15] fs: use helper bio_add_page() instead of open coding on > [PATCH 15/15] Documentation: update notes in biovecs about The changes to dm.c and dm.h should be in the "dm:" patch, not "md:". But I don't think the sequence is right. You cannot remove ->merge_bvec_fn for *any* stacked device until *all* devi= ces make use of blk_queue_split() (or otherwise handle arbitrarily large bios). I think it would be easiest to: - add blk_queue_split() and call it from common code before ->make_request= _fn is called. The ensure all devices can accept arbitrarily large bios. - driver-by-driver remove merge_bvec_fn and make sure the the driver can c= ope with arbitrary bios themselve, calling blk_queue_split in the make_reque= st function only if needed - finally remove the call to blk_queue_split from the common code. Does that make sense to others? Thanks, NeilBrown >=20 > > > > Thanks. > > > >> > >> patch 1: > >> > >> add ->bio_split and blk_queue_split > >> > >> patch 2..n: > >> > >> one for each non-trivial driver that implements ->merge_bvec_fn to > >> remove it and instead split bios in ->make_request. The md patch > >> to do the right thing in chunk_aligned_read goes into the general > >> md patch here. The bcache patch also goes into this series. > >> > >> patch n+1: > >> > >> - add blk_queue_split calls for remaining trivial drivers > >> > >> patch n+2: > >> > >> - remove ->merge_bvec_fn and checking of max_sectors a for all > >> drivers, simplify bio_add_page > >> > >> patch n+2: > >> > >> - remove splitting in blkdev_issue_discard > >> > >> patch n+3 > >> > >> - remove bio_fits_rdev > >> > >> patch n+4 > >> > >> - remove bio_get_nr_vecs > >> > >> patch n+4 > >> > >> - use bio_add_page > >> > >> patch n+5 > >> > >> - update documentation --Sig_/8MMpc4P+nLG6sfy3WjHJiEp Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIVAwUBVWT7rTnsnt1WYoG5AQJKSxAAs6GGlr3ZzmKBAVFRz+Ojk9LE12C4i2vq 6FM+4lkcBBB+i+O6ppiJpwvOz2dn936mz2r+jb8h1c3j4IxTmNDoaIMv+R/+r5s5 r0otXtDQf7y6P8gXLzHhicuVcf9elwh+QitQ6oS7od6rVOaSJnJinTpDl9StWtq8 AeSp/WQruLUrG8r3C19E4Ye1FJ21KXx3SL8LwKSCh4jCq7Fzdta1OhDsfJr5Z5pt 4J9EM06FbKFKrc3/sVa0/yE0cBz14v0CeVJal/bVVTzEungcJyj/TezYym5sstzM caWY23o2H9GGxEtV7laQoRUGfrnMI8jBuaG+Qp5EpW5D5zclOnR12Qbz+3sKXxll vR6sI4qgy10CvBZqGBMjPume3dcPTcpV+H8fcxZTzlxqEUSINK/2nPAe2cPvm0nV 00AoOAIvKtblf/XXJY6VRuSPlDTB0yvRbbLWJWHYkDec96/F5orY0eYtAK9I5vWI 52vVYrzgcVmEpDRjhb+Hx5ThCO1X60f59AVBLEyM08tKqHlnXqPX1CptyrHuJdkA u8g7+Qd66tmYB9kicvMOqWsJhIvH1lVXeuLJpT69aiXupMO0jC8S07ino9/Tzk0e J/4E+ZqL5NmrbdzabeKTUIkj4zfiig+FCVn3uw7N3wat9aCtGCHgbXM8JSfNT3Hf sW2l5hLbImk= =Tau2 -----END PGP SIGNATURE----- --Sig_/8MMpc4P+nLG6sfy3WjHJiEp--