linux-kernel - [PATCH 5.10 21/41] block: clear GD_NEED_PART_SCAN later in bdev_disk

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Date:   Fri,  9 Apr 2021 11:53:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chris Chiu <chris.chiu@...onical.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 21/41] block: clear GD_NEED_PART_SCAN later in bdev_disk_changed

From: Chris Chiu <chris.chiu@...onical.com>

[ Upstream commit 5116784039f0421e9a619023cfba3e302c3d9adc ]

The GD_NEED_PART_SCAN is set by bdev_check_media_change to initiate
a partition scan while removing a block device. It should be cleared
after blk_drop_paritions because blk_drop_paritions could return
-EBUSY and then the consequence __blkdev_get has no chance to do
delete_partition if GD_NEED_PART_SCAN already cleared.

It causes some problems on some card readers. Ex. Realtek card
reader 0bda:0328 and 0bda:0158. The device node of the partition
will not disappear after the memory card removed. Thus the user
applications can not update the device mapping correctly.

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1920874
Signed-off-by: Chris Chiu <chris.chiu@...onical.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Link: https://lore.kernel.org/r/20210323085219.24428-1-chris.chiu@canonical.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/block_dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index fe201b757baa..6516051807b8 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1404,13 +1404,13 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate)
 
 	lockdep_assert_held(&bdev->bd_mutex);
 
-	clear_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
-
 rescan:
 	ret = blk_drop_partitions(bdev);
 	if (ret)
 		return ret;
 
+	clear_bit(GD_NEED_PART_SCAN, &disk->state);
+
 	/*
 	 * Historically we only set the capacity to zero for devices that
 	 * support partitions (independ of actually having partitions created).
-- 
2.30.2