From patchwork Sat Jan 9 10:42:52 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 359770 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50F48C433E6 for ; Sat, 9 Jan 2021 10:48:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D75323A1E for ; Sat, 9 Jan 2021 10:48:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726852AbhAIKsk (ORCPT ); Sat, 9 Jan 2021 05:48:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725956AbhAIKsk (ORCPT ); Sat, 9 Jan 2021 05:48:40 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90A5BC0617A3; Sat, 9 Jan 2021 02:47:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=OuO8kXBwOVg2a0qlGOHd+KBfCRFHK5StyY10tKFHVS8=; b=VeZFfshSf9Ix0EcE41evKramMP jn5vZju+vCViJE/nGVWD9jxUQ4zuFVyTiarcua3S0nKzo7UtPQ3qIvoDASsUtzBegY+tOdk/8xOJU SYiCsPCW7JhSvmDRJr6Lorz+5qbHCPXUzOT+g++UB3pV/FLKrxmLDRt7hyQoDNuep1RFkMyXYIeP3 NbSdIibjh9ZG/rL8H6VX4+ebq8g12ZsuZ8yV1igsjWwJ+tzmCwWzJWONL0ss00jAta8hq2Gpvoi6u KxUiqhoHwmWMvQ0hEVuPfAn7NQKRcax/09Nx9Mv0b82q3hBiycqDf9GEL376cuzLHC4Vov+fP779e nSUoU8fw==; Received: from [2001:4bb8:19b:e528:4197:a20:99de:e7b0] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1kyBl7-000TC6-Dn; Sat, 09 Jan 2021 10:46:20 +0000 From: Christoph Hellwig To: Jens Axboe Cc: "Martin K . Petersen" , Oleksii Kurochko , Sagi Grimberg , Mike Snitzer , Ilya Dryomov , Dongsheng Yang , ceph-devel@vger.kernel.org, dm-devel@redhat.com, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org Subject: [PATCH 4/6] block: propagate BLKROSET on the whole device to all partitions Date: Sat, 9 Jan 2021 11:42:52 +0100 Message-Id: <20210109104254.1077093-5-hch@lst.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210109104254.1077093-1-hch@lst.de> References: <20210109104254.1077093-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Change the policy so that a BLKROSET on the whole device also affects partitions. To quote Martin K. Petersen: It's very common for database folks to twiddle the read-only state of block devices and partitions. I know that our users will find it very counter-intuitive that setting /dev/sda read-only won't prevent writes to /dev/sda1. The existing behavior is inconsistent in the sense that doing: # blockdev --setro /dev/sda # echo foo > /dev/sda1 permits writes. But: # blockdev --setro /dev/sda # echo foo > /dev/sda1 doesn't. And a subsequent: # blockdev --setrw /dev/sda # echo foo > /dev/sda1 doesn't work either since sda1's read-only policy has been inherited from the whole-disk device. You need to do: # blockdev --rereadpt after setting the whole-disk device rw to effectuate the same change on the partitions, otherwise they are stuck being read-only indefinitely. However, setting the read-only policy on a partition does *not* require the revalidate step. As a matter of fact, doing the revalidate will blow away the policy setting you just made. So the user needs to take different actions depending on whether they are trying to read-protect a whole-disk device or a partition. Despite using the same ioctl. That is really confusing. I have lost count how many times our customers have had data clobbered because of ambiguity of the existing whole-disk device policy. The current behavior violates the principle of least surprise by letting the user think they write protected the whole disk when they actually didn't. Suggested-by: Martin K. Petersen Signed-off-by: Christoph Hellwig Reviewed-by: Martin K. Petersen Reviewed-by: Hannes Reinecke --- block/genhd.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index e70bdc9b0893c1..10c76320510fef 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1658,8 +1658,7 @@ EXPORT_SYMBOL(set_disk_ro); int bdev_read_only(struct block_device *bdev) { - return bdev->bd_read_only || - test_bit(GD_READ_ONLY, &bdev->bd_disk->state); + return bdev->bd_read_only || get_disk_ro(bdev->bd_disk); } EXPORT_SYMBOL(bdev_read_only);