From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031084AbbD1WJk (ORCPT ); Tue, 28 Apr 2015 18:09:40 -0400 Received: from cantor2.suse.de ([195.135.220.15]:47723 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030826AbbD1WJi (ORCPT ); Tue, 28 Apr 2015 18:09:38 -0400 Date: Wed, 29 Apr 2015 08:09:19 +1000 From: NeilBrown To: Ming Lin Cc: linux-kernel@vger.kernel.org, Christoph Hellwig , Jens Axboe , Kent Overstreet , Dongsu Park , Lars Ellenberg , drbd-user@lists.linbit.com, Jiri Kosina , Yehuda Sadeh , Sage Weil , Alex Elder , ceph-devel@vger.kernel.org, Alasdair Kergon , Mike Snitzer , dm-devel@redhat.com, linux-raid@vger.kernel.org, Christoph Hellwig , "Martin K. Petersen" Subject: Re: [PATCH 07/10] block: kill merge_bvec_fn() completely Message-ID: <20150429080919.342fddfd@notabene.brown> In-Reply-To: <1430203717-13307-8-git-send-email-mlin@kernel.org> References: <1430203717-13307-1-git-send-email-mlin@kernel.org> <1430203717-13307-8-git-send-email-mlin@kernel.org> 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_/1hOXNlv0I_n25BYxBJ9Vcng"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/1hOXNlv0I_n25BYxBJ9Vcng Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 27 Apr 2015 23:48:34 -0700 Ming Lin wrote: > From: Kent Overstreet >=20 > As generic_make_request() is now able to handle arbitrarily sized bios, > it's no longer necessary for each individual block driver to define its > own ->merge_bvec_fn() callback. Remove every invocation completely. This patch it just a little premature I think. md/raid5 still assumes read requests will mostly fit within a single chunk (which merge_bvec_fn encourages) so they can be serviced without using the stripe-cache. You've just broken that assumption. I think 'chunk_aligned_read' needs to get a loop using bio_split, a bit like raid0, first. Thanks, NeilBrown --Sig_/1hOXNlv0I_n25BYxBJ9Vcng Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIVAwUBVUAFDznsnt1WYoG5AQKzlA//RLbb7rnxiJ1OpNg/IHGyCg5GyokjhBK7 N25OUZnKyz8BbWgstR4i+I3YVBw1kxpHNh1e3nadOt04qmiXtI4K35HXIHkzpMCg 4DTPGvwi8Q2uYDQa2cHFFRgxnXvrCuNIH8BJQFYp7I+9tgHD7jUYY/roU/HvQlMC 6AMYwz4Z9JK6rIxPFfq5YsH4AW6W7Ut4EnTPMKVXfFXQDnfLdboRzSxt1EwVRRF0 dH5/ZChqMabNTYhB6HAnalsxpSauknxsNom3nuMxxEml7JUY9RUq6T8kS+H/c32m 5ctIZurQO8lXlb+YPoHFxtiTNalQshkW9DJILORDWyqOOiN64X4eLmfaOBKai8nV COW/9OaFb5re3yr9cdigMylfrj7hPOS/kuccAs2V0mjyWLIIrJBdIOMH8xrnVW0g pextCfa0jwhoJ1/1W8Ovur64T+qFENtDGT+9QJfiIKrCTuIworhr9RCycNVdJM9O rY19PaUwnDRBZ0U2i5gQvOg4uKy2+AJp4WFxiZLRNSVhwaZ2S9Kr1o5QADEk9NfR 2vYBdU69YlhO6vGLAnRgzdqKlA6+NCCva4vkFxQvNm61d8YP8asWdrEGYnqdoXYt 5H2WB+s7olvMgyGqV8ks79wUU4K4InCkx7J5/AW9JxlJ40rHNPdn7/5FT/zjSedZ Nlmw51dDQqg= =yECD -----END PGP SIGNATURE----- --Sig_/1hOXNlv0I_n25BYxBJ9Vcng--