Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755089AbaKEOIY (ORCPT ); Wed, 5 Nov 2014 09:08:24 -0500 Received: from mail-wi0-f180.google.com ([209.85.212.180]:45236 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754543AbaKEOIV (ORCPT ); Wed, 5 Nov 2014 09:08:21 -0500 Message-ID: <545A2F52.3040303@plexistor.com> Date: Wed, 05 Nov 2014 16:08:18 +0200 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Jens Axboe , Matthew Wilcox , Dmitry Monakhov CC: linux-kernel , linux-fsdevel Subject: [PATCH 4/5] brd: Request from fdisk 4k alignment References: <545A2D69.8090003@plexistor.com> In-Reply-To: <545A2D69.8090003@plexistor.com> 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 From: Boaz Harrosh Because of the direct_access() API which returns a PFN. partitions better start on 4K boundary, else offset ZERO of a partition will not be aligned and blk_direct_access() will fail the call. By setting blk_queue_physical_block_size(PAGE_SIZE) we can communicate this to fdisk and friends. Note that blk_queue_physical_block_size() also trashes io_min, but we can leave this one to be 512. io_min as opposed to physical_block_size will actually change Kernel behavior, but physical_block_size is not used by Kernel except being exported to user-mode. before this patch running fdisk on a default size brd of 4M the first sector offered is 34 (BAD), but after this patch it will be 40, ie 8 sectors aligned. Also when entering some random partition sizes the next partition-start sector is offered 8 sectors aligned after this patch. (Please note that with fdisk the user can still enter bad values, only the offered default values will be correct) Signed-off-by: Boaz Harrosh --- drivers/block/brd.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index a7463c959..0026998 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -486,10 +486,17 @@ static struct brd_device *brd_alloc(int i) brd->brd_queue = blk_alloc_queue(GFP_KERNEL); if (!brd->brd_queue) goto out_free_dev; + blk_queue_make_request(brd->brd_queue, brd_make_request); blk_queue_max_hw_sectors(brd->brd_queue, 1024); blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); + /* This is so fdisk will align partitions on 4k, because of + * direct_access API needing 4k alignment, returning a PFN + */ + blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE); + brd->brd_queue->limits.io_min = 512; /* Don't use the accessor */ + brd->brd_queue->limits.discard_granularity = PAGE_SIZE; brd->brd_queue->limits.max_discard_sectors = UINT_MAX; brd->brd_queue->limits.discard_zeroes_data = 1; -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/