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Subject: Re: [PATCH v2 3/6] xprtrdma: Refactor invocations of offset_in_page()
To:     Chuck Lever <chuck.lever@oracle.com>, linux-nfs@vger.kernel.org,
        linux-rdma@vger.kernel.org
References: <161236925476.1030487.10407536259816633879.stgit@manet.1015granger.net>
 <161236944700.1030487.6859398915626711523.stgit@manet.1015granger.net>
From:   Tom Talpey <tom@talpey.com>
Message-ID: <d0bbab3e-851c-3388-3d1c-cbc6249a6803@talpey.com>
Date:   Wed, 3 Feb 2021 13:09:59 -0500
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This looks good, but the earlier 1/6 patch depends on the offset_in_page
conversion in rpcrdma_convert_kvec. Won't that complicate any bisection?

Reviewed-By: Tom Talpey <tom@talpey.com>

On 2/3/2021 11:24 AM, Chuck Lever wrote:
> Clean up so that offset_in_page() is invoked less often in the
> most common case, which is mapping xdr->pages.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>   net/sunrpc/xprtrdma/frwr_ops.c  |    8 +++-----
>   net/sunrpc/xprtrdma/rpc_rdma.c  |    4 ++--
>   net/sunrpc/xprtrdma/xprt_rdma.h |    2 +-
>   3 files changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
> index 13a50f77dddb..766a1048a48a 100644
> --- a/net/sunrpc/xprtrdma/frwr_ops.c
> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> @@ -306,16 +306,14 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
>   	if (nsegs > ep->re_max_fr_depth)
>   		nsegs = ep->re_max_fr_depth;
>   	for (i = 0; i < nsegs;) {
> -		sg_set_page(&mr->mr_sg[i],
> -			    seg->mr_page,
> -			    seg->mr_len,
> -			    offset_in_page(seg->mr_offset));
> +		sg_set_page(&mr->mr_sg[i], seg->mr_page,
> +			    seg->mr_len, seg->mr_offset);
>   
>   		++seg;
>   		++i;
>   		if (ep->re_mrtype == IB_MR_TYPE_SG_GAPS)
>   			continue;
> -		if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
> +		if ((i < nsegs && seg->mr_offset) ||
>   		    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
>   			break;
>   	}
> diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
> index 529adb6ad4db..b3e66b8f65ab 100644
> --- a/net/sunrpc/xprtrdma/rpc_rdma.c
> +++ b/net/sunrpc/xprtrdma/rpc_rdma.c
> @@ -215,7 +215,7 @@ rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
>   {
>   	if (vec->iov_len) {
>   		seg->mr_page = virt_to_page(vec->iov_base);
> -		seg->mr_offset = vec->iov_base;
> +		seg->mr_offset = offset_in_page(vec->iov_base);
>   		seg->mr_len = vec->iov_len;
>   		++seg;
>   		++(*n);
> @@ -248,7 +248,7 @@ rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
>   	page_base = offset_in_page(xdrbuf->page_base);
>   	while (len) {
>   		seg->mr_page = *ppages;
> -		seg->mr_offset = (char *)page_base;
> +		seg->mr_offset = page_base;
>   		seg->mr_len = min_t(u32, PAGE_SIZE - page_base, len);
>   		len -= seg->mr_len;
>   		++ppages;
> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
> index 02971e183989..ed1c5444fb9d 100644
> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
> @@ -287,7 +287,7 @@ enum {
>   struct rpcrdma_mr_seg {
>   	u32		mr_len;		/* length of segment */
>   	struct page	*mr_page;	/* underlying struct page */
> -	char		*mr_offset;	/* IN: page offset, OUT: iova */
> +	u64		mr_offset;	/* IN: page offset, OUT: iova */
>   };
>   
>   /* The Send SGE array is provisioned to send a maximum size
> 
> 
>