[lustre-devel] [PATCH 04/28] lustre: ptlrpc: Do not assert when bd_nob_transferred != 0

[NeilBrown]

On Sun, Oct 14 2018, James Simmons wrote:

> From: Doug Oucharek <dougso at me.com>
>
> There is a case in the routine ptlrpc_register_bulk() where we were
> asserting if bd_nob_transferred != 0 when not resending.  There is
> evidence that network errors can create a situation where
> this does happen. So we should not be asserting!
>
> This patch changes that assert to an error return code of -EIO.
>
> Signed-off-by: Doug Oucharek <dougso at me.com>
> WC-bug-id: https://jira.whamcloud.com/browse/LU-9828
> Reviewed-on: https://review.whamcloud.com/28491
> Reviewed-by: Dmitry Eremin <dmitry.eremin at intel.com>
> Reviewed-by: Sonia Sharma <sharmaso at whamcloud.com>
> Reviewed-by: Oleg Drokin <green at whamcloud.com>
> Signed-off-by: James Simmons <jsimmons at infradead.org>
> ---
>  drivers/staging/lustre/lustre/ptlrpc/niobuf.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/ptlrpc/niobuf.c b/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
> index 27eb1c0..7e7db24 100644
> --- a/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
> +++ b/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
> @@ -139,8 +139,12 @@ static int ptlrpc_register_bulk(struct ptlrpc_request *req)
>  	/* cleanup the state of the bulk for it will be reused */
>  	if (req->rq_resend || req->rq_send_state == LUSTRE_IMP_REPLAY)
>  		desc->bd_nob_transferred = 0;
> -	else
> -		LASSERT(desc->bd_nob_transferred == 0);
> +	else if (desc->bd_nob_transferred != 0)
> +		/* If the network failed after an RPC was sent, this condition
> +		 * could happen.  Rather than assert (was here before), return
> +		 * an EIO error.
> +		 */
> +		return -EIO;

This looks weird, and the justification is rather lame.
I wonder if this is an attempt to fix the same problem that the smp_mb()
in the previous patch was attempting to fix (and I'm not yet convinced
that either is the correct fix).

NeilBrown


>  
>  	desc->bd_failure = 0;
>  
> -- 
> 1.8.3.1
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