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Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com Subject: Re: [PATCH V10 18/19] block: kill QUEUE_FLAG_NO_SG_MERGE Message-ID: <20181116021811.GM23828@vader> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-19-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181115085306.9910-19-ming.lei@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 15, 2018 at 04:53:05PM +0800, Ming Lei wrote: > Since bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"), > physical segment number is mainly figured out in blk_queue_split() for > fast path, and the flag of BIO_SEG_VALID is set there too. > > Now only blk_recount_segments() and blk_recalc_rq_segments() use this > flag. > > Basically blk_recount_segments() is bypassed in fast path given BIO_SEG_VALID > is set in blk_queue_split(). > > For another user of blk_recalc_rq_segments(): > > - run in partial completion branch of blk_update_request, which is an unusual case > > - run in blk_cloned_rq_check_limits(), still not a big problem if the flag is killed > since dm-rq is the only user. > > Multi-page bvec is enabled now, QUEUE_FLAG_NO_SG_MERGE doesn't make sense any more. This commit message wasn't very clear. Is it the case that QUEUE_FLAG_NO_SG_MERGE is no longer set by any drivers?