[Ocfs2-devel] [PATCH] ocfs2: direct write will call ocfs2_rw_unlock() twice when doing aio+dio

[Junxiao Bi]

On 08/24/2015 03:23 PM, Ryan Ding wrote:
> Orabug: 21612107
> 
> Use wrong return value in ocfs2_file_write_iter(). This will cause
> ocfs2_rw_unlock() be called both in write_iter & end_io, and trigger a BUG_ON.
> 
> This issue exist since commit 7da839c475894ea872ec909a5d2e83dddccff5be.
Better say:
This issue is introduced by commit 7da839c47589 ("ocfs2: use
__generic_file_write_iter()") , or checkpatch will report a style error.
Other looks good.

Reviewed-by: Junxiao Bi <junxiao.bi at oracle.com>

Thanks,
Junxiao.
> 
> Signed-off-by: Ryan Ding <ryan.ding at oracle.com>
> ---
>  fs/ocfs2/file.c |   28 ++++++++++++++--------------
>  1 files changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 719f7f4..33efa33 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2372,6 +2372,20 @@ relock:
>  	/* buffered aio wouldn't have proper lock coverage today */
>  	BUG_ON(written == -EIOCBQUEUED && !(iocb->ki_flags & IOCB_DIRECT));
>  
> +	/*
> +	 * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
> +	 * function pointer which is called when o_direct io completes so that
> +	 * it can unlock our rw lock.
> +	 * Unfortunately there are error cases which call end_io and others
> +	 * that don't.  so we don't have to unlock the rw_lock if either an
> +	 * async dio is going to do it in the future or an end_io after an
> +	 * error has already done it.
> +	 */
> +	if ((written == -EIOCBQUEUED) || (!ocfs2_iocb_is_rw_locked(iocb))) {
> +		rw_level = -1;
> +		unaligned_dio = 0;
> +	}
> +
>  	if (unlikely(written <= 0))
>  		goto no_sync;
>  
> @@ -2396,20 +2410,6 @@ relock:
>  	}
>  
>  no_sync:
> -	/*
> -	 * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
> -	 * function pointer which is called when o_direct io completes so that
> -	 * it can unlock our rw lock.
> -	 * Unfortunately there are error cases which call end_io and others
> -	 * that don't.  so we don't have to unlock the rw_lock if either an
> -	 * async dio is going to do it in the future or an end_io after an
> -	 * error has already done it.
> -	 */
> -	if ((ret == -EIOCBQUEUED) || (!ocfs2_iocb_is_rw_locked(iocb))) {
> -		rw_level = -1;
> -		unaligned_dio = 0;
> -	}
> -
>  	if (unaligned_dio) {
>  		ocfs2_iocb_clear_unaligned_aio(iocb);
>  		mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
>