[PATCH] knfsd: Replace two page lists in struct svc_rqst with one

We are planning to increase RPCSVC_MAXPAGES from about 8 to about 256.  This
means we need to be a bit careful about arrays of size RPCSVC_MAXPAGES.

struct svc_rqst contains two such arrays.  However the there are never more
that RPCSVC_MAXPAGES pages in the two arrays together, so only one array is
needed.

The two arrays are for the pages holding the request, and the pages holding
the reply.  Instead of two arrays, we can simply keep an index into where the
first reply page is.

This patch also removes a number of small inline functions that probably
server to obscure what is going on rather than clarify it, and opencode the
needed functionality.

Also remove the 'rq_restailpage' variable as it is *always* 0.  i.e.  if the
response 'xdr' structure has a non-empty tail it is always in the same pages
as the head.

 check counters are initilised and incr properly
 check for consistant usage of ++ etc
 maybe extra some inlines for common approach
 general review

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Magnus Maatta <novell@kiruna.se>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 29 insertions, 37 deletions

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 638c0b5..558692d 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1191,7 +1191,6 @@ svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp)
 		resbuf->tail[0].iov_base = resbuf->head[0].iov_base
 						+ resbuf->head[0].iov_len;
 		resbuf->tail[0].iov_len = 0;
-		rqstp->rq_restailpage = 0;
 		resv = &resbuf->tail[0];
 	} else {
 		resv = &resbuf->tail[0];
@@ -1240,7 +1239,7 @@ svcauth_gss_wrap_resp_priv(struct svc_rqst *rqstp)
 	inpages = resbuf->pages;
 	/* XXX: Would be better to write some xdr helper functions for
 	 * nfs{2,3,4}xdr.c that place the data right, instead of copying: */
-	if (resbuf->tail[0].iov_base && rqstp->rq_restailpage == 0) {
+	if (resbuf->tail[0].iov_base) {
 		BUG_ON(resbuf->tail[0].iov_base >= resbuf->head[0].iov_base
 							+ PAGE_SIZE);
 		BUG_ON(resbuf->tail[0].iov_base < resbuf->head[0].iov_base);
@@ -1258,7 +1257,6 @@ svcauth_gss_wrap_resp_priv(struct svc_rqst *rqstp)
 		resbuf->tail[0].iov_base = resbuf->head[0].iov_base
 			+ resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE;
 		resbuf->tail[0].iov_len = 0;
-		rqstp->rq_restailpage = 0;
 	}
 	if (gss_wrap(gsd->rsci->mechctx, offset, resbuf, inpages))
 		return -ENOMEM;
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index a99e67b..f4a509a 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -417,18 +417,15 @@ svc_init_buffer(struct svc_rqst *rqstp, unsigned int size)
 	if (size > RPCSVC_MAXPAYLOAD)
 		size = RPCSVC_MAXPAYLOAD;
 	pages = 2 + (size+ PAGE_SIZE -1) / PAGE_SIZE;
-	rqstp->rq_argused = 0;
-	rqstp->rq_resused = 0;
 	arghi = 0;
 	BUG_ON(pages > RPCSVC_MAXPAGES);
 	while (pages) {
 		struct page *p = alloc_page(GFP_KERNEL);
 		if (!p)
 			break;
-		rqstp->rq_argpages[arghi++] = p;
+		rqstp->rq_pages[arghi++] = p;
 		pages--;
 	}
-	rqstp->rq_arghi = arghi;
 	return ! pages;
 }
 
@@ -438,14 +435,10 @@ svc_init_buffer(struct svc_rqst *rqstp, unsigned int size)
 static void
 svc_release_buffer(struct svc_rqst *rqstp)
 {
-	while (rqstp->rq_arghi)
-		put_page(rqstp->rq_argpages[--rqstp->rq_arghi]);
-	while (rqstp->rq_resused) {
-		if (rqstp->rq_respages[--rqstp->rq_resused] == NULL)
-			continue;
-		put_page(rqstp->rq_respages[rqstp->rq_resused]);
-	}
-	rqstp->rq_argused = 0;
+	int i;
+	for (i=0; i<ARRAY_SIZE(rqstp->rq_pages); i++)
+		if (rqstp->rq_pages[i])
+			put_page(rqstp->rq_pages[i]);
 }
 
 /*
@@ -707,10 +700,10 @@ svc_process(struct svc_rqst *rqstp)
 	/* setup response xdr_buf.
 	 * Initially it has just one page 
 	 */
-	svc_take_page(rqstp); /* must succeed */
+	rqstp->rq_resused = 1;
 	resv->iov_base = page_address(rqstp->rq_respages[0]);
 	resv->iov_len = 0;
-	rqstp->rq_res.pages = rqstp->rq_respages+1;
+	rqstp->rq_res.pages = rqstp->rq_respages + 1;
 	rqstp->rq_res.len = 0;
 	rqstp->rq_res.page_base = 0;
 	rqstp->rq_res.page_len = 0;
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 4de8626..25096d5 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -313,7 +313,7 @@ svc_sock_release(struct svc_rqst *rqstp)
 
 	svc_release_skb(rqstp);
 
-	svc_free_allpages(rqstp);
+	svc_free_res_pages(rqstp);
 	rqstp->rq_res.page_len = 0;
 	rqstp->rq_res.page_base = 0;
 
@@ -412,7 +412,8 @@ svc_sendto(struct svc_rqst *rqstp, struct xdr_buf *xdr)
 	/* send head */
 	if (slen == xdr->head[0].iov_len)
 		flags = 0;
-	len = kernel_sendpage(sock, rqstp->rq_respages[0], 0, xdr->head[0].iov_len, flags);
+	len = kernel_sendpage(sock, rqstp->rq_respages[0], 0,
+				  xdr->head[0].iov_len, flags);
 	if (len != xdr->head[0].iov_len)
 		goto out;
 	slen -= xdr->head[0].iov_len;
@@ -437,8 +438,9 @@ svc_sendto(struct svc_rqst *rqstp, struct xdr_buf *xdr)
 	}
 	/* send tail */
 	if (xdr->tail[0].iov_len) {
-		result = kernel_sendpage(sock, rqstp->rq_respages[rqstp->rq_restailpage],
-					     ((unsigned long)xdr->tail[0].iov_base)& (PAGE_SIZE-1),
+		result = kernel_sendpage(sock, rqstp->rq_respages[0],
+					     ((unsigned long)xdr->tail[0].iov_base)
+					        & (PAGE_SIZE-1),
 					     xdr->tail[0].iov_len, 0);
 
 		if (result > 0)
@@ -708,9 +710,11 @@ svc_udp_recvfrom(struct svc_rqst *rqstp)
 	if (len <= rqstp->rq_arg.head[0].iov_len) {
 		rqstp->rq_arg.head[0].iov_len = len;
 		rqstp->rq_arg.page_len = 0;
+		rqstp->rq_respages = rqstp->rq_pages+1;
 	} else {
 		rqstp->rq_arg.page_len = len - rqstp->rq_arg.head[0].iov_len;
-		rqstp->rq_argused += (rqstp->rq_arg.page_len + PAGE_SIZE - 1)/ PAGE_SIZE;
+		rqstp->rq_respages = rqstp->rq_pages + 1 +
+			(rqstp->rq_arg.page_len + PAGE_SIZE - 1)/ PAGE_SIZE;
 	}
 
 	if (serv->sv_stats)
@@ -1053,11 +1057,12 @@ svc_tcp_recvfrom(struct svc_rqst *rqstp)
 	vlen = PAGE_SIZE;
 	pnum = 1;
 	while (vlen < len) {
-		vec[pnum].iov_base = page_address(rqstp->rq_argpages[rqstp->rq_argused++]);
+		vec[pnum].iov_base = page_address(rqstp->rq_pages[pnum]);
 		vec[pnum].iov_len = PAGE_SIZE;
 		pnum++;
 		vlen += PAGE_SIZE;
 	}
+	rqstp->rq_respages = &rqstp->rq_pages[pnum];
 
 	/* Now receive data */
 	len = svc_recvfrom(rqstp, vec, pnum, len);
@@ -1209,7 +1214,7 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
 	struct svc_sock		*svsk =NULL;
 	struct svc_serv		*serv = rqstp->rq_server;
 	struct svc_pool		*pool = rqstp->rq_pool;
-	int			len;
+	int			len, i;
 	int 			pages;
 	struct xdr_buf		*arg;
 	DECLARE_WAITQUEUE(wait, current);
@@ -1226,27 +1231,22 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
 			"svc_recv: service %p, wait queue active!\n",
 			 rqstp);
 
-	/* Initialize the buffers */
-	/* first reclaim pages that were moved to response list */
-	svc_pushback_allpages(rqstp);
 
 	/* now allocate needed pages.  If we get a failure, sleep briefly */
 	pages = 2 + (serv->sv_bufsz + PAGE_SIZE -1) / PAGE_SIZE;
-	while (rqstp->rq_arghi < pages) {
-		struct page *p = alloc_page(GFP_KERNEL);
-		if (!p) {
-			schedule_timeout_uninterruptible(msecs_to_jiffies(500));
-			continue;
+	for (i=0; i < pages ; i++)
+		while (rqstp->rq_pages[i] == NULL) {
+			struct page *p = alloc_page(GFP_KERNEL);
+			if (!p)
+				schedule_timeout_uninterruptible(msecs_to_jiffies(500));
+			rqstp->rq_pages[i] = p;
 		}
-		rqstp->rq_argpages[rqstp->rq_arghi++] = p;
-	}
 
 	/* Make arg->head point to first page and arg->pages point to rest */
 	arg = &rqstp->rq_arg;
-	arg->head[0].iov_base = page_address(rqstp->rq_argpages[0]);
+	arg->head[0].iov_base = page_address(rqstp->rq_pages[0]);
 	arg->head[0].iov_len = PAGE_SIZE;
-	rqstp->rq_argused = 1;
-	arg->pages = rqstp->rq_argpages + 1;
+	arg->pages = rqstp->rq_pages + 1;
 	arg->page_base = 0;
 	/* save at least one page for response */
 	arg->page_len = (pages-2)*PAGE_SIZE;
@@ -1704,6 +1704,7 @@ static int svc_deferred_recv(struct svc_rqst *rqstp)
 	rqstp->rq_prot        = dr->prot;
 	rqstp->rq_addr        = dr->addr;
 	rqstp->rq_daddr       = dr->daddr;
+	rqstp->rq_respages    = rqstp->rq_pages;
 	return dr->argslen<<2;
 }