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

[Chuck Lever]

On Jan 9, 2015, at 3:14 PM, J. Bruce Fields  wrote:

> 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?

No change in behavior.

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

OK.

> 
> --b.
> 
>> Signed-off-by: Chuck Lever 
>> ---
>> 
>> 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 
>> #include 
>> #include 
>> -#include 
>> #include 
>> #include 
>> #include 
>> @@ -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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>> the body of a message to majord...@vger.kernel.org
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com



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

[J. Bruce Fields]

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 
> ---
> 
>  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 
>  #include 
>  #include 
> -#include 
>  #include 
>  #include 
>  #include 
> @@ -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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[PATCH v1 09/10] Move read list XDR round-up logic

[Chuck Lever]

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... ")
Signed-off-by: Chuck Lever 
---

 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 
 #include 
 #include 
-#include 
 #include 
 #include 
 #include 
@@ -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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