From 92dd256bd4c58260787df2369f9781babfaf5d1f Mon Sep 17 00:00:00 2001
From: Andrew Gallatin <gallatin@FreeBSD.org>
Date: Sun, 5 Jun 2005 17:13:23 +0000
Subject: [PATCH] Allow sends sent from non page-aligned userspace addresses to
 be considered for zero-copy sends.

Reviewed by: alc
Submitted by: Romer Gil at Rice University
---
 sys/kern/uipc_cow.c    | 17 +++++++++--------
 sys/kern/uipc_socket.c | 11 ++++-------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/sys/kern/uipc_cow.c b/sys/kern/uipc_cow.c
index 8d6d06e508e..1ee937366f0 100644
--- a/sys/kern/uipc_cow.c
+++ b/sys/kern/uipc_cow.c
@@ -102,12 +102,13 @@ socow_setup(struct mbuf *m0, struct uio *uio)
 	struct iovec *iov;
 	struct vmspace *vmspace;
 	struct vm_map *map;
-	vm_offset_t uva;
+	vm_offset_t offset, uva;
 	int s;
 
 	vmspace = curproc->p_vmspace;
 	map = &vmspace->vm_map;
 	uva = (vm_offset_t) uio->uio_iov->iov_base;
+	offset = uva & PAGE_MASK;
 
 	s = splvm();
 
@@ -158,22 +159,22 @@ socow_setup(struct mbuf *m0, struct uio *uio)
 	/* 
 	 * attach to mbuf
 	 */
-	m0->m_data = (caddr_t)sf_buf_kva(sf);
-	m0->m_len = PAGE_SIZE;
 	MEXTADD(m0, sf_buf_kva(sf), PAGE_SIZE, socow_iodone, sf, M_RDONLY,
 	    EXT_SFBUF);
+	m0->m_len = PAGE_SIZE - offset;
+	m0->m_data = (caddr_t)sf_buf_kva(sf) + offset;
 	socow_stats.success++;
 
 	iov = uio->uio_iov;
-	iov->iov_base = (char *)iov->iov_base + PAGE_SIZE;
-	iov->iov_len -= PAGE_SIZE;
-	uio->uio_resid -= PAGE_SIZE;
-	uio->uio_offset += PAGE_SIZE;
+	iov->iov_base = (char *)iov->iov_base + m0->m_len;
+	iov->iov_len -= m0->m_len;
+	uio->uio_resid -= m0->m_len;
+	uio->uio_offset += m0->m_len;
 	if (iov->iov_len == 0) {
 		uio->uio_iov++;
 		uio->uio_iovcnt--;
 	}
 
 	splx(s);
-	return(1);
+	return(m0->m_len);
 }
diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 694747d2a01..4c6f8bf5ff7 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -742,11 +742,9 @@ restart:
 				    space>=PAGE_SIZE &&
 				    uio->uio_iov->iov_len>=PAGE_SIZE) {
 					so_zerocp_stats.size_ok++;
-					if (!((vm_offset_t)
-					  uio->uio_iov->iov_base & PAGE_MASK)){
-						so_zerocp_stats.align_ok++;
-						cow_send = socow_setup(m, uio);
-					}
+					so_zerocp_stats.align_ok++;
+					cow_send = socow_setup(m, uio);
+					len = cow_send;
 				}
 				if (!cow_send) {
 					MCLGET(m, M_TRYWAIT);
@@ -756,8 +754,7 @@ restart:
 					} else {
 						len = min(min(MCLBYTES, resid), space);
 					}
-				} else
-					len = PAGE_SIZE;
+				}
 #else /* ZERO_COPY_SOCKETS */
 				if (top == NULL) {
 					m = m_getcl(M_TRYWAIT, MT_DATA, M_PKTHDR);