Re: [PATCH v1 09/10] Move read list XDR round-up logic

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

On Fri, Jan 09, 2015 at 02:23:11PM -0500, Chuck Lever wrote:
> Simpler approach, and this needs to be done before the tail is
> copied to the end of the read list (pre-requisite for a subsequent
> patch).
> 
> Fixes: e560e3b510d2 ("svcrdma: Add zero padding if the client... ")

Wait, does this actually fix a bug in that previous commit is or it
just cleanup?

If the latter, the "Fixes:.." line is confusing, just mention it in the
text ("Simpler approach compared to the original attempt in
e560e3b510d2...").

--b.

> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> 
>  net/sunrpc/xprtrdma/svc_rdma_recvfrom.c |   37 ++++++++-----------------------
>  1 files changed, 9 insertions(+), 28 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> index 36cf51a..a345cad 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> @@ -43,7 +43,6 @@
>  #include <linux/sunrpc/debug.h>
>  #include <linux/sunrpc/rpc_rdma.h>
>  #include <linux/spinlock.h>
> -#include <linux/highmem.h>
>  #include <asm/unaligned.h>
>  #include <rdma/ib_verbs.h>
>  #include <rdma/rdma_cm.h>
> @@ -434,6 +433,15 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
>  		}
>  	}
>  
> +	/* Read list may need XDR round-up (see RFC 5666, s. 3.7) */
> +	if (page_offset & 3) {
> +		u32 pad = 4 - (page_offset & 3);
> +
> +		head->arg.page_len += pad;
> +		head->arg.len += pad;
> +		head->arg.buflen += pad;
> +	}
> +
>  	ret = 1;
>  	head->position = position;
>  
> @@ -446,32 +454,6 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
>  	return ret;
>  }
>  
> -/*
> - * To avoid a separate RDMA READ just for a handful of zero bytes,
> - * RFC 5666 section 3.7 allows the client to omit the XDR zero pad
> - * in chunk lists.
> - */
> -static void
> -rdma_fix_xdr_pad(struct xdr_buf *buf)
> -{
> -	unsigned int page_len = buf->page_len;
> -	unsigned int size = (XDR_QUADLEN(page_len) << 2) - page_len;
> -	unsigned int offset, pg_no;
> -	char *p;
> -
> -	if (size == 0)
> -		return;
> -
> -	pg_no = page_len >> PAGE_SHIFT;
> -	offset = page_len & ~PAGE_MASK;
> -	p = page_address(buf->pages[pg_no]);
> -	memset(p + offset, 0, size);
> -
> -	buf->page_len += size;
> -	buf->buflen += size;
> -	buf->len += size;
> -}
> -
>  static int rdma_read_complete(struct svc_rqst *rqstp,
>  			      struct svc_rdma_op_ctxt *head)
>  {
> @@ -499,7 +481,6 @@ static int rdma_read_complete(struct svc_rqst *rqstp,
>  	}
>  
>  	/* Point rq_arg.pages past header */
> -	rdma_fix_xdr_pad(&head->arg);
>  	rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
>  	rqstp->rq_arg.page_len = head->arg.page_len;
>  	rqstp->rq_arg.page_base = head->arg.page_base;
> 
> --
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