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Subject: Re: [PATCH 4.9 15/39] jbd2: add the missing unlock_buffer() in the
 error path of jbd2_write_superblock()
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <linux-kernel@vger.kernel.org>
CC:     <stable@vger.kernel.org>, Ritesh Harjani <riteshh@linux.ibm.com>,
        <stable@kernel.org>, Theodore Tso <tytso@mit.edu>
References: <20200824082348.445866152@linuxfoundation.org>
 <20200824082349.270439673@linuxfoundation.org>
From:   "zhangyi (F)" <yi.zhang@huawei.com>
Message-ID: <72009693-6c2a-df4f-f93a-31b5924e7790@huawei.com>
Date:   Mon, 24 Aug 2020 19:15:25 +0800
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Hi，Greg

The problem this patch want to fix only exists on the kernel both
538bcaa6261b and 742b06b5628f these two upstream patches were merged,
but 538bcaa6261b was not merged to 4.9, so we don't need this patch
for 4.9.

Thanks,
Yi.

On 2020/8/24 16:31, Greg Kroah-Hartman wrote:
> From: zhangyi (F) <yi.zhang@huawei.com>
> 
> commit ef3f5830b859604eda8723c26d90ab23edc027a4 upstream.
> 
> jbd2_write_superblock() is under the buffer lock of journal superblock
> before ending that superblock write, so add a missing unlock_buffer() in
> in the error path before submitting buffer.
> 
> Fixes: 742b06b5628f ("jbd2: check superblock mapped prior to committing")
> Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
> Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
> Cc: stable@kernel.org
> Link: https://lore.kernel.org/r/20200620061948.2049579-1-yi.zhang@huawei.com
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> ---
>  fs/jbd2/journal.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1340,8 +1340,10 @@ static int jbd2_write_superblock(journal
>  	int ret;
>  
>  	/* Buffer got discarded which means block device got invalidated */
> -	if (!buffer_mapped(bh))
> +	if (!buffer_mapped(bh)) {
> +		unlock_buffer(bh);
>  		return -EIO;
> +	}
>  
>  	trace_jbd2_write_superblock(journal, write_flags);
>  	if (!(journal->j_flags & JBD2_BARRIER))
> 
> 
> 
> .
>