From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752413AbdEBDrR (ORCPT ); Mon, 1 May 2017 23:47:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:34574 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752383AbdEBDrM (ORCPT ); Mon, 1 May 2017 23:47:12 -0400 From: NeilBrown To: Jens Axboe Date: Tue, 02 May 2017 13:42:26 +1000 Subject: [PATCH 13/13] block: don't check for BIO_MAX_PAGES in blk_bio_segment_split() Cc: linux-block@vger.kernel.org, Ming Lei , linux-kernel@vger.kernel.org Message-ID: <149369654638.5146.3067734913419940612.stgit@noble> In-Reply-To: <149369628671.5146.4865312503373040039.stgit@noble> References: <149369628671.5146.4865312503373040039.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org blk_bio_segment_split() makes sure bios have no more than BIO_MAX_PAGES entries in the bi_io_vec. This was done because bio_clone_bioset() (when given a mempool bioset) could not handle larger io_vecs. No driver uses bio_clone_bioset() any more, they all use bio_clone_fast() if anything, and bio_clone_fast() doesn't clone the bi_io_vec. The main user of of bio_clone_bioset() at this level is bounce.c, and bouncing now happens before blk_bio_segment_split(), so that is not of concern. So remove the big helpful comment and the code. Signed-off-by: NeilBrown --- block/blk-merge.c | 16 ---------------- 1 file changed, 16 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index e7862e9dcc39..cea544ec5d96 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -108,25 +108,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - unsigned bvecs = 0; bio_for_each_segment(bv, bio, iter) { /* - * With arbitrary bio size, the incoming bio may be very - * big. We have to split the bio into small bios so that - * each holds at most BIO_MAX_PAGES bvecs because - * bio_clone_bioset() can fail to allocate big bvecs. - * - * Those drivers which will need to use bio_clone_bioset() - * should tell us in some way. For now, impose the - * BIO_MAX_PAGES limit on all queues. - * - * TODO: handle users of bio_clone_bioset() differently. - */ - if (bvecs++ >= BIO_MAX_PAGES) - goto split; - - /* * If the queue doesn't support SG gaps and adding this * offset would create a gap, disallow it. */