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Subject: Re: [PATCH] ocfs2: Fix handle refcount leak in two exception handling
 paths
To:     Chenyuan Mi <cymi20@fudan.edu.cn>
Cc:     yuanxzhang@fudan.edu.cn, Xiyu Yang <xiyuyang19@fudan.edu.cn>,
        Xin Tan <tanxin.ctf@gmail.com>, Mark Fasheh <mark@fasheh.com>,
        Joel Becker <jlbec@evilplan.org>, ocfs2-devel@oss.oracle.com,
        linux-kernel@vger.kernel.org
References: <20210908062603.6723-1-cymi20@fudan.edu.cn>
From:   Joseph Qi <joseph.qi@linux.alibaba.com>
Message-ID: <636c032f-b0ee-8b1f-998d-bed2869297a0@linux.alibaba.com>
Date:   Wed, 8 Sep 2021 17:05:09 +0800
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Hi Chenyuan,
Thanks for reporting this bug.
But the fix looks incorrect. It will commit transaction once more in
normal case.
The simplest way is calling ocfs2_commit_trans() in each of the error
handling path before goto bail.

if (status < 0) {
	ocfs2_commit_trans(osb, handle);
	mlog_errno(status);
	goto bail;
}

Thanks,
Joseph

On 9/8/21 2:26 PM, Chenyuan Mi wrote:
> The reference counting issue happens in two exception handling 
> paths of ocfs2_replay_truncate_records(). When executing these 
> two exception handling paths, the function forgets to decrease 
> the refcount of handle increased by ocfs2_start_trans(), causing 
> a refcount leak.
> 
> Fix this issue by using ocfs2_commit_trans() to decrease the 
> refcount of handle in two handling paths.
> 
> Signed-off-by: Chenyuan Mi <cymi20@fudan.edu.cn>
> Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
> 
> ---
>  fs/ocfs2/alloc.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
> index f1cc8258d34a..b87960cdda0d 100644
> --- a/fs/ocfs2/alloc.c
> +++ b/fs/ocfs2/alloc.c
> @@ -5941,7 +5941,7 @@ static int ocfs2_replay_truncate_records(struct ocfs2_super *osb,
>  						 OCFS2_JOURNAL_ACCESS_WRITE);
>  		if (status < 0) {
>  			mlog_errno(status);
> -			goto bail;
> +			goto bail_commit;
>  		}
>  
>  		tl->tl_used = cpu_to_le16(i);
> @@ -5965,7 +5965,7 @@ static int ocfs2_replay_truncate_records(struct ocfs2_super *osb,
>  						     num_clusters);
>  			if (status < 0) {
>  				mlog_errno(status);
> -				goto bail;
> +				goto bail_commit;
>  			}
>  		}
>  
> @@ -5975,6 +5975,8 @@ static int ocfs2_replay_truncate_records(struct ocfs2_super *osb,
>  
>  	osb->truncated_clusters = 0;
>  
> +bail_commit:
> +	ocfs2_commit_trans(osb, handle);
>  bail:
>  	return status;
>  }
>