Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751887AbbEZXml (ORCPT ); Tue, 26 May 2015 19:42:41 -0400 Received: from mail.kernel.org ([198.145.29.136]:33615 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751823AbbEZXmi (ORCPT ); Tue, 26 May 2015 19:42:38 -0400 MIME-Version: 1.0 In-Reply-To: <20150527090309.2cddf33b@notabene.brown> 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> <20150527090309.2cddf33b@notabene.brown> Date: Tue, 26 May 2015 16:42:35 -0700 Message-ID: Subject: Re: [PATCH v4 06/11] md/raid5: get rid of bio_fits_rdev() From: Ming Lin To: NeilBrown Cc: Ming Lin , Christoph Hellwig , lkml , Kent Overstreet , Jens Axboe , Dongsu Park , linux-raid@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4131 Lines: 125 On Tue, May 26, 2015 at 4:03 PM, NeilBrown wrote: > 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. >> >> Here is the reordering. >> https://git.kernel.org/cgit/linux/kernel/git/mlin/linux.git/log/?h=block-generic-req >> >> I'll post it if you are OK. >> >> [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:". Will move it. > > But I don't think the sequence is right. > > You cannot remove ->merge_bvec_fn for *any* stacked device until *all* devices > 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. For "common code", do you mean "generic_make_request()" diff --git a/block/blk-core.c b/block/blk-core.c index fbbb337..bb6455b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1942,6 +1942,7 @@ void generic_make_request(struct bio *bio) do { struct request_queue *q = bdev_get_queue(bio->bi_bdev); + blk_queue_split(q, &bio, q->bio_split); q->make_request_fn(q, bio); bio = bio_list_pop(current->bio_list); > - driver-by-driver remove merge_bvec_fn and make sure the the driver can cope > with arbitrary bios themselve, calling blk_queue_split in the make_request > function only if needed > - finally remove the call to blk_queue_split from the common code. > > Does that make sense to others? > > Thanks, > NeilBrown > >> >> > >> > 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/