From patchwork Tue Dec 8 16:28:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 340400 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=-16.8 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,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 0575FC1B0D8 for ; Tue, 8 Dec 2020 16:38:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D12FE233CF for ; Tue, 8 Dec 2020 16:38:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730381AbgLHQiE (ORCPT ); Tue, 8 Dec 2020 11:38:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728602AbgLHQiE (ORCPT ); Tue, 8 Dec 2020 11:38:04 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62DD4C0613D6; Tue, 8 Dec 2020 08:37:24 -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=elpIgX+cTsb2dqzbwyG4mhhxmB2j6M8UmSJFUU3cmP0=; b=ku/Ut2+yV4kFeNDDzU3/Gz0gty xKg3I1ZYaBfKuo8vMnrV/wa+5sdvtI2PqU0AYrGf3mU7w+pj9DFVIZWt3CAk70dXi2BwusOpNCG97 hbpVaV3f1thTtnt571Ucm6mf+53WHPZHNQlOe9gwFtSBdD8cPPbv+dNbWqjk/vDXIyfcN/+wKNl42 Vjm6YaZj9hVudn2S1PgeVPwyfE5mcCz1aSKFDfPTB0Z8Pu7jeRdKLwRKeGF80Or+HvuJkf79iNwd5 fHIcakd96svG/ThN9KKezO5QqtECF8R9/HMTrFCyX+7HJ+Wg13U+eZPPrQQeISP6RjKmr4k+nKHay bWj2U4Tg==; Received: from [2001:4bb8:188:f36:7a30:8a2b:aea3:231b] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmfzI-0001Nu-He; Tue, 08 Dec 2020 16:37:16 +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: Tue, 8 Dec 2020 17:28:27 +0100 Message-Id: <20201208162829.2424563-5-hch@lst.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201208162829.2424563-1-hch@lst.de> References: <20201208162829.2424563-1-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 --- block/genhd.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index d9f989c1514123..6e51ecb9280aca 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1656,8 +1656,7 @@ 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);