From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by ml01.01.org (Postfix) with ESMTP id 2E5531A1EC1 for ; Mon, 14 Mar 2016 15:51:00 -0700 (PDT) Date: Mon, 14 Mar 2016 16:50:17 -0600 From: Ross Zwisler Subject: Re: [PATCH 0/4] Remove un-needed 'major' registration when alloc_disk(0) is used. Message-ID: <20160314225017.GC19926@linux.intel.com> References: <20160309215702.20904.61407.stgit@noble> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160309215702.20904.61407.stgit@noble> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: NeilBrown Cc: Jens Axboe , Maxim Levitsky , linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Keith Busch List-ID: On Thu, Mar 10, 2016 at 08:59:28AM +1100, NeilBrown wrote: > When alloc_disk(0) is used, the ->major number is ignored and > irrelevant. Yet several drivers register a major number anyway. > > This series of patches removes the pointless registrations. The pmem > driver also does this, but a patch has already been sent for that > driver. > > Note that I am not in a position to test these beyond simple compile > testing. > > Thanks, > NeilBrown > > > --- > > NeilBrown (4): > nvdimm/blk: don't allocate unused major device number > nvdimm/btt: don't allocate unused major device number > memstick: don't allocate unused major for ms_block > NVMe: don't allocate unused nvme_major > > > drivers/memstick/core/ms_block.c | 17 ++--------------- > drivers/nvdimm/blk.c | 18 +----------------- > drivers/nvdimm/btt.c | 19 ++----------------- > drivers/nvme/host/core.c | 16 +--------------- > 4 files changed, 6 insertions(+), 64 deletions(-) There are several other drivers that allocate a major, but then use it for some small number of minors (1 for null_blk.c and 16 for virtio_blk.c). They both have GENHD_FL_EXT_DEVT set, so I think what happens is that after we exhaust the allocated minors they hop over to having BLOCK_EXT_MAJOR as a major and a dynamically assigned minor. It seems like these could easily be converted in the same way so they'd use BLOCK_EXT_MAJOR for their major and have a bunch of dynamically assigned minors. Does this break something I'm not seeing? Yay for this series, by the way. :) _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm