From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F94BC6FD1C for ; Wed, 22 Mar 2023 07:59:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229642AbjCVH7b (ORCPT ); Wed, 22 Mar 2023 03:59:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229522AbjCVH7b (ORCPT ); Wed, 22 Mar 2023 03:59:31 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B09171E1F7 for ; Wed, 22 Mar 2023 00:58:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1679471932; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=L8Ne1p2uicICYZ7xBH6jyVNfKiAf/Oat/UHSOLhhvvU=; b=SERR3/lw+aYWBUdUyizbQaquJM+zd+PBknOSU6SvsYngbgrUN9VDYORE8rt2cqdrGrwtMH i3ZQfsz6Gtd/hkIrsI1lfDfffecszbwgEJ3qYYH7Ofp0kFjQYJjwPuxxLpT7qzQwjZTmhP Z5jcEngjQfL+yNtBqOj0tHsVW9Wt5nw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-423-ew3BiCPcNQGT8dgmsdGtbw-1; Wed, 22 Mar 2023 03:58:46 -0400 X-MC-Unique: ew3BiCPcNQGT8dgmsdGtbw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E198385C075; Wed, 22 Mar 2023 07:58:45 +0000 (UTC) Received: from ovpn-8-17.pek2.redhat.com (ovpn-8-18.pek2.redhat.com [10.72.8.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 730B940C20FA; Wed, 22 Mar 2023 07:58:39 +0000 (UTC) Date: Wed, 22 Mar 2023 15:58:35 +0800 From: Ming Lei To: Yu Kuai Cc: jack@suse.cz, hch@infradead.org, axboe@kernel.dk, yukuai3@huawei.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, ming.lei@redhat.com Subject: Re: [PATCH] block: don't set GD_NEED_PART_SCAN if scan partition failed Message-ID: References: <20230322035926.1791317-1-yukuai1@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230322035926.1791317-1-yukuai1@huaweicloud.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Mar 22, 2023 at 11:59:26AM +0800, Yu Kuai wrote: > From: Yu Kuai > > Currently if disk_scan_partitions() failed, GD_NEED_PART_SCAN will still > set, and partition scan will be proceed again when blkdev_get_by_dev() > is called. However, this will cause a problem that re-assemble partitioned > raid device will creat partition for underlying disk. > > Test procedure: > > mdadm -CR /dev/md0 -l 1 -n 2 /dev/sda /dev/sdb -e 1.0 > sgdisk -n 0:0:+100MiB /dev/md0 > blockdev --rereadpt /dev/sda > blockdev --rereadpt /dev/sdb > mdadm -S /dev/md0 > mdadm -A /dev/md0 /dev/sda /dev/sdb > > Test result: underlying disk partition and raid partition can be > observed at the same time > > Note that this can still happen in come corner cases that > GD_NEED_PART_SCAN can be set for underlying disk while re-assemble raid > device. > > Fixes: e5cfefa97bcc ("block: fix scan partition for exclusively open device again") > Signed-off-by: Yu Kuai The issue still can't be avoided completely, such as, after rebooting, /dev/sda1 & /dev/md0p1 can be observed at the same time. And this one should be underlying partitions scanned before re-assembling raid, I guess it may not be easy to avoid. Also seems the following change added in e5cfefa97bcc isn't necessary: /* Make sure the first partition scan will be proceed */ if (get_capacity(disk) && !(disk->flags & GENHD_FL_NO_PART) && !test_bit(GD_SUPPRESS_PART_SCAN, &disk->state)) set_bit(GD_NEED_PART_SCAN, &disk->state); since the following disk_scan_partitions() in device_add_disk() should cover partitions scan. > --- > block/genhd.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/block/genhd.c b/block/genhd.c > index 08bb1a9ec22c..a72e27d6779d 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -368,7 +368,6 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode) > if (disk->open_partitions) > return -EBUSY; > > - set_bit(GD_NEED_PART_SCAN, &disk->state); > /* > * If the device is opened exclusively by current thread already, it's > * safe to scan partitons, otherwise, use bd_prepare_to_claim() to > @@ -381,12 +380,19 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode) > return ret; > } > > + set_bit(GD_NEED_PART_SCAN, &disk->state); > bdev = blkdev_get_by_dev(disk_devt(disk), mode & ~FMODE_EXCL, NULL); > if (IS_ERR(bdev)) > ret = PTR_ERR(bdev); > else > blkdev_put(bdev, mode & ~FMODE_EXCL); > > + /* > + * If blkdev_get_by_dev() failed early, GD_NEED_PART_SCAN is still set, > + * and this will cause that re-assemble partitioned raid device will > + * creat partition for underlying disk. > + */ > + clear_bit(GD_NEED_PART_SCAN, &disk->state); I feel GD_NEED_PART_SCAN becomes a bit hard to follow. So far, it is only consumed by blkdev_get_whole(), and cleared in bdev_disk_changed(). That means partition scan can be retried if bdev_disk_changed() fails. Another mess is that more drivers start to touch this flag, such as nbd/sd, probably it is better to change them into one API of blk_disk_need_partition_scan(), and hide implementation detail to drivers. thanks, Ming