From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:27827 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729814AbgLCHMj (ORCPT ); Thu, 3 Dec 2020 02:12:39 -0500 Date: Thu, 3 Dec 2020 15:10:55 +0800 From: Ming Lei Subject: Re: [PATCH 3/9] block: store a block_device pointer in struct bio Message-ID: <20201203071055.GA633702@T590> References: <20201201165424.2030647-1-hch@lst.de> <20201201165424.2030647-4-hch@lst.de> <20201203063941.GA629758@T590> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201203063941.GA629758@T590> List-ID: To: Christoph Hellwig Cc: Jens Axboe , Tejun Heo , Coly Li , Song Liu , dm-devel@redhat.com, linux-bcache@vger.kernel.org, linux-raid@vger.kernel.org, linux-s390@vger.kernel.org, linux-block@vger.kernel.org On Thu, Dec 03, 2020 at 02:40:04PM +0800, Ming Lei wrote: > On Tue, Dec 01, 2020 at 05:54:18PM +0100, Christoph Hellwig wrote: > > Replace the gendisk pointer in struct bio with a pointer to the newly > > improved struct block device. From that the gendisk can be trivially > > accessed with an extra indirection, but it also allows to directly > > look up all information related to partition remapping. > > The extra indirection is often done in fast path, so just wondering why > you don't consider to embed gendisk into block_device? Then the extra > indirection can be avoided. oops, that is only possible for disk, and indirection is still needed for partitions. Thanks, Ming