[PATCH] RPC: extract socket logic common to both client and server

 Clean-up: Move some code that is common to both RPC client- and server-side
 socket transports into its own source file, net/sunrpc/socklib.c.

 Test-plan:
 Compile kernel with CONFIG_NFS enabled.  Millions of fsx operations over
 UDP, client and server.  Connectathon over UDP.

 Version: Thu, 11 Aug 2005 16:03:09 -0400

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 175 insertions, 0 deletions

diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
new file mode 100644
index 00000000000..8f97e90f36c
--- /dev/null
+++ b/net/sunrpc/socklib.c
@@ -0,0 +1,175 @@
+/*
+ * linux/net/sunrpc/socklib.c
+ *
+ * Common socket helper routines for RPC client and server
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/types.h>
+#include <linux/pagemap.h>
+#include <linux/udp.h>
+#include <linux/sunrpc/xdr.h>
+
+
+/**
+ * skb_read_bits - copy some data bits from skb to internal buffer
+ * @desc: sk_buff copy helper
+ * @to: copy destination
+ * @len: number of bytes to copy
+ *
+ * Possibly called several times to iterate over an sk_buff and copy
+ * data out of it.
+ */
+static size_t skb_read_bits(skb_reader_t *desc, void *to, size_t len)
+{
+	if (len > desc->count)
+		len = desc->count;
+	if (skb_copy_bits(desc->skb, desc->offset, to, len))
+		return 0;
+	desc->count -= len;
+	desc->offset += len;
+	return len;
+}
+
+/**
+ * skb_read_and_csum_bits - copy and checksum from skb to buffer
+ * @desc: sk_buff copy helper
+ * @to: copy destination
+ * @len: number of bytes to copy
+ *
+ * Same as skb_read_bits, but calculate a checksum at the same time.
+ */
+static size_t skb_read_and_csum_bits(skb_reader_t *desc, void *to, size_t len)
+{
+	unsigned int	csum2, pos;
+
+	if (len > desc->count)
+		len = desc->count;
+	pos = desc->offset;
+	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
+	desc->csum = csum_block_add(desc->csum, csum2, pos);
+	desc->count -= len;
+	desc->offset += len;
+	return len;
+}
+
+/**
+ * xdr_partial_copy_from_skb - copy data out of an skb
+ * @xdr: target XDR buffer
+ * @base: starting offset
+ * @desc: sk_buff copy helper
+ * @copy_actor: virtual method for copying data
+ *
+ */
+ssize_t xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, skb_reader_t *desc, skb_read_actor_t copy_actor)
+{
+	struct page	**ppage = xdr->pages;
+	unsigned int	len, pglen = xdr->page_len;
+	ssize_t		copied = 0;
+	int		ret;
+
+	len = xdr->head[0].iov_len;
+	if (base < len) {
+		len -= base;
+		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
+		copied += ret;
+		if (ret != len || !desc->count)
+			goto out;
+		base = 0;
+	} else
+		base -= len;
+
+	if (unlikely(pglen == 0))
+		goto copy_tail;
+	if (unlikely(base >= pglen)) {
+		base -= pglen;
+		goto copy_tail;
+	}
+	if (base || xdr->page_base) {
+		pglen -= base;
+		base += xdr->page_base;
+		ppage += base >> PAGE_CACHE_SHIFT;
+		base &= ~PAGE_CACHE_MASK;
+	}
+	do {
+		char *kaddr;
+
+		/* ACL likes to be lazy in allocating pages - ACLs
+		 * are small by default but can get huge. */
+		if (unlikely(*ppage == NULL)) {
+			*ppage = alloc_page(GFP_ATOMIC);
+			if (unlikely(*ppage == NULL)) {
+				if (copied == 0)
+					copied = -ENOMEM;
+				goto out;
+			}
+		}
+
+		len = PAGE_CACHE_SIZE;
+		kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
+		if (base) {
+			len -= base;
+			if (pglen < len)
+				len = pglen;
+			ret = copy_actor(desc, kaddr + base, len);
+			base = 0;
+		} else {
+			if (pglen < len)
+				len = pglen;
+			ret = copy_actor(desc, kaddr, len);
+		}
+		flush_dcache_page(*ppage);
+		kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
+		copied += ret;
+		if (ret != len || !desc->count)
+			goto out;
+		ppage++;
+	} while ((pglen -= len) != 0);
+copy_tail:
+	len = xdr->tail[0].iov_len;
+	if (base < len)
+		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
+out:
+	return copied;
+}
+
+/**
+ * csum_partial_copy_to_xdr - checksum and copy data
+ * @xdr: target XDR buffer
+ * @skb: source skb
+ *
+ * We have set things up such that we perform the checksum of the UDP
+ * packet in parallel with the copies into the RPC client iovec.  -DaveM
+ */
+int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
+{
+	skb_reader_t	desc;
+
+	desc.skb = skb;
+	desc.offset = sizeof(struct udphdr);
+	desc.count = skb->len - desc.offset;
+
+	if (skb->ip_summed == CHECKSUM_UNNECESSARY)
+		goto no_checksum;
+
+	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
+	if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_and_csum_bits) < 0)
+		return -1;
+	if (desc.offset != skb->len) {
+		unsigned int csum2;
+		csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
+		desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
+	}
+	if (desc.count)
+		return -1;
+	if ((unsigned short)csum_fold(desc.csum))
+		return -1;
+	return 0;
+no_checksum:
+	if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_bits) < 0)
+		return -1;
+	if (desc.count)
+		return -1;
+	return 0;
+}