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Date:   Mon, 27 Apr 2020 18:10:16 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
Cc:     Christoph Hellwig <hch@lst.de>, Qian Cai <cai@lca.pw>,
        Jens Axboe <axboe@kernel.dk>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        linux-block@vger.kernel.org, linux-s390@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: s390 boot woe due to "block: fix busy device checking in
 blk_drop_partitions"
Message-ID: <20200427161016.GA9719@lst.de>
References: <AD16A450-794F-4EEA-A7BF-42452F18294A@lca.pw> <20200410054544.GA17923@lst.de> <20200423110738.GA102241@blackbook>
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In-Reply-To: <20200423110738.GA102241@blackbook>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Michal,

can you try the patch below?  That should solve the udev race for real
hopefully.

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index da693e6a834e5..20dbe4cf62cf9 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1318,6 +1318,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	if (err)
 		goto out_unfreeze;
 
+	/* don't send uevents until we've finished the partition scan */
+	dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
+
 	if (lo->lo_offset != info->lo_offset ||
 	    lo->lo_sizelimit != info->lo_sizelimit) {
 		/* kill_bdev should have truncated all the pages */
@@ -1377,6 +1380,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	if (partscan)
 		loop_reread_partitions(lo, bdev);
 
+	dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
 	return err;
 }