Re: [PATCH] svcrdma: send_write() must not overflow the device's max sge

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Jul 09, 2014 at 01:49:15PM -0500, Steve Wise wrote:
> Function send_write() must stop creating sges when it reaches the device
> max and return the amount sent in the RDMA Write to the caller.

Queueing up for 3.17, thanks.--b.

> 
> Signed-off-by: Steve Wise <swise@opengridcomputing.com>
> ---
> 
>  net/sunrpc/xprtrdma/svc_rdma_sendto.c |   39 +++++++++++++--------------------
>  1 files changed, 15 insertions(+), 24 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> index 49fd21a..9f1b506 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
> @@ -192,6 +192,8 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
>  		xdr_sge_no++;
>  		BUG_ON(xdr_sge_no > vec->count);
>  		bc -= sge_bytes;
> +		if (sge_no == xprt->sc_max_sge)
> +			break;
>  	}
>  
>  	/* Prepare WRITE WR */
> @@ -209,7 +211,7 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
>  	atomic_inc(&rdma_stat_write);
>  	if (svc_rdma_send(xprt, &write_wr))
>  		goto err;
> -	return 0;
> +	return write_len - bc;
>   err:
>  	svc_rdma_unmap_dma(ctxt);
>  	svc_rdma_put_context(ctxt, 0);
> @@ -225,7 +227,6 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
>  {
>  	u32 xfer_len = rqstp->rq_res.page_len + rqstp->rq_res.tail[0].iov_len;
>  	int write_len;
> -	int max_write;
>  	u32 xdr_off;
>  	int chunk_off;
>  	int chunk_no;
> @@ -239,8 +240,6 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
>  	res_ary = (struct rpcrdma_write_array *)
>  		&rdma_resp->rm_body.rm_chunks[1];
>  
> -	max_write = xprt->sc_max_sge * PAGE_SIZE;
> -
>  	/* Write chunks start at the pagelist */
>  	for (xdr_off = rqstp->rq_res.head[0].iov_len, chunk_no = 0;
>  	     xfer_len && chunk_no < arg_ary->wc_nchunks;
> @@ -260,23 +259,21 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
>  						write_len);
>  		chunk_off = 0;
>  		while (write_len) {
> -			int this_write;
> -			this_write = min(write_len, max_write);
>  			ret = send_write(xprt, rqstp,
>  					 ntohl(arg_ch->rs_handle),
>  					 rs_offset + chunk_off,
>  					 xdr_off,
> -					 this_write,
> +					 write_len,
>  					 vec);
> -			if (ret) {
> +			if (ret <= 0) {
>  				dprintk("svcrdma: RDMA_WRITE failed, ret=%d\n",
>  					ret);
>  				return -EIO;
>  			}
> -			chunk_off += this_write;
> -			xdr_off += this_write;
> -			xfer_len -= this_write;
> -			write_len -= this_write;
> +			chunk_off += ret;
> +			xdr_off += ret;
> +			xfer_len -= ret;
> +			write_len -= ret;
>  		}
>  	}
>  	/* Update the req with the number of chunks actually used */
> @@ -293,7 +290,6 @@ static int send_reply_chunks(struct svcxprt_rdma *xprt,
>  {
>  	u32 xfer_len = rqstp->rq_res.len;
>  	int write_len;
> -	int max_write;
>  	u32 xdr_off;
>  	int chunk_no;
>  	int chunk_off;
> @@ -311,8 +307,6 @@ static int send_reply_chunks(struct svcxprt_rdma *xprt,
>  	res_ary = (struct rpcrdma_write_array *)
>  		&rdma_resp->rm_body.rm_chunks[2];
>  
> -	max_write = xprt->sc_max_sge * PAGE_SIZE;
> -
>  	/* xdr offset starts at RPC message */
>  	nchunks = ntohl(arg_ary->wc_nchunks);
>  	for (xdr_off = 0, chunk_no = 0;
> @@ -330,24 +324,21 @@ static int send_reply_chunks(struct svcxprt_rdma *xprt,
>  						write_len);
>  		chunk_off = 0;
>  		while (write_len) {
> -			int this_write;
> -
> -			this_write = min(write_len, max_write);
>  			ret = send_write(xprt, rqstp,
>  					 ntohl(ch->rs_handle),
>  					 rs_offset + chunk_off,
>  					 xdr_off,
> -					 this_write,
> +					 write_len,
>  					 vec);
> -			if (ret) {
> +			if (ret <= 0) {
>  				dprintk("svcrdma: RDMA_WRITE failed, ret=%d\n",
>  					ret);
>  				return -EIO;
>  			}
> -			chunk_off += this_write;
> -			xdr_off += this_write;
> -			xfer_len -= this_write;
> -			write_len -= this_write;
> +			chunk_off += ret;
> +			xdr_off += ret;
> +			xfer_len -= ret;
> +			write_len -= ret;
>  		}
>  	}
>  	/* Update the req with the number of chunks actually used */
>