linux-kernel - [PATCH 5.2 023/144] bdev: Fixup error handling in blkdev

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Message-Id: <20190814165800.813745526@linuxfoundation.org>
Date:   Wed, 14 Aug 2019 18:59:39 +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, Jan Kara <jack@...e.cz>,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.2 023/144] bdev: Fixup error handling in blkdev_get()

From: Jan Kara <jack@...e.cz>

commit e91455bad5cff40a8c232f2204a5104127e3fec2 upstream.

Commit 89e524c04fa9 ("loop: Fix mount(2) failure due to race with
LOOP_SET_FD") converted blkdev_get() to use the new helpers for
finishing claiming of a block device. However the conversion botched the
error handling in blkdev_get() and thus the bdev has been marked as held
even in case __blkdev_get() returned error. This led to occasional
warnings with block/001 test from blktests like:

kernel: WARNING: CPU: 5 PID: 907 at fs/block_dev.c:1899 __blkdev_put+0x396/0x3a0

Correct the error handling.

CC: stable@...r.kernel.org
Fixes: 89e524c04fa9 ("loop: Fix mount(2) failure due to race with LOOP_SET_FD")
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/block_dev.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1723,7 +1723,10 @@ int blkdev_get(struct block_device *bdev
 
 		/* finish claiming */
 		mutex_lock(&bdev->bd_mutex);
-		bd_finish_claiming(bdev, whole, holder);
+		if (!res)
+			bd_finish_claiming(bdev, whole, holder);
+		else
+			bd_abort_claiming(bdev, whole, holder);
 		/*
 		 * Block event polling for write claims if requested.  Any
 		 * write holder makes the write_holder state stick until