Index: sys/kern/uipc_syscalls.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/uipc_syscalls.c,v
retrieving revision 1.142
diff -u -r1.142 uipc_syscalls.c
--- sys/kern/uipc_syscalls.c	6 Mar 2003 04:48:19 -0000	1.142
+++ sys/kern/uipc_syscalls.c	10 Mar 2003 23:29:55 -0000
@@ -1637,12 +1637,16 @@
  * Get an sf_buf from the freelist. Will block if none are available.
  */
 struct sf_buf *
-sf_buf_alloc()
+sf_buf_alloc(struct vm_page *m)
 {
 	struct sf_buf *sf;
 	int error;
 
 	mtx_lock(&sf_freelist.sf_lock);
+	if ((sf = m->sf_buf) != NULL) {
+		sf->ref_count++;
+		goto done;
+	}
 	while ((sf = SLIST_FIRST(&sf_freelist.sf_head)) == NULL) {
 		sf_buf_alloc_want++;
 		error = msleep(&sf_freelist, &sf_freelist.sf_lock, PVM|PCATCH,
@@ -1650,13 +1654,42 @@
 		sf_buf_alloc_want--;
 
 		/*
-		 * If we got a signal, don't risk going back to sleep. 
+		 * If we got a signal, don't risk going back to sleep.
 		 */
 		if (error)
-			break;
+			goto done;
 	}
-	if (sf != NULL)
+	SLIST_REMOVE_HEAD(&sf_freelist.sf_head, free_list);
+	sf->ref_count = 1;
+	sf->m = m;
+	pmap_qenter(sf->kva, &m, 1);
+	m->sf_buf = sf;
+ done:
+	mtx_unlock(&sf_freelist.sf_lock);
+	return (sf);
+}
+
+/*
+ * Get an sf_buf from the freelist. Will return NULL if none are
+ * available.
+ */
+struct sf_buf *
+sf_buf_alloc_nb(struct vm_page *m)
+{
+	struct sf_buf *sf;
+
+	mtx_lock(&sf_freelist.sf_lock);
+	if ((sf = m->sf_buf) != NULL) {
+		sf->ref_count++;
+		goto done;
+	}
+	sf_buf_alloc_want++;
+	sf = SLIST_FIRST(&sf_freelist.sf_head);
+	if (sf != NULL) {
 		SLIST_REMOVE_HEAD(&sf_freelist.sf_head, free_list);
+		sf_buf_alloc_want--;
+	}
+ done:
 	mtx_unlock(&sf_freelist.sf_lock);
 	return (sf);
 }
@@ -1673,8 +1706,19 @@
 	struct vm_page *m;
 
 	sf = dtosf(addr);
-	pmap_qremove((vm_offset_t)addr, 1);
+	mtx_lock(&sf_freelist.sf_lock);
 	m = sf->m;
+	sf->ref_count--;
+	if (sf->ref_count == 0) {
+		m->sf_buf = NULL;
+		pmap_qremove((vm_offset_t)addr, 1);
+		sf->m = NULL;
+		SLIST_INSERT_HEAD(&sf_freelist.sf_head, sf, free_list);
+		if (sf_buf_alloc_want > 0)
+			wakeup_one(&sf_freelist);
+	}
+	mtx_unlock(&sf_freelist.sf_lock);
+
 	vm_page_lock_queues();
 	vm_page_unwire(m, 0);
 	/*
@@ -1685,12 +1729,6 @@
 	if (m->wire_count == 0 && m->object == NULL)
 		vm_page_free(m);
 	vm_page_unlock_queues();
-	sf->m = NULL;
-	mtx_lock(&sf_freelist.sf_lock);
-	SLIST_INSERT_HEAD(&sf_freelist.sf_head, sf, free_list);
-	if (sf_buf_alloc_want > 0)
-		wakeup_one(&sf_freelist);
-	mtx_unlock(&sf_freelist.sf_lock);
 }
 
 /*
@@ -1929,26 +1967,25 @@
 		vm_page_unlock_queues();
 
 		/*
-		 * Get a sendfile buf. We usually wait as long as necessary,
-		 * but this wait can be interrupted.
+		 * Get a sendfile buf.
 		 */
-		if ((sf = sf_buf_alloc()) == NULL) {
+		if (so->so_state & SS_NBIO) {
+			if ((sf = sf_buf_alloc_nb(pg)) == NULL)
+				error = EAGAIN;
+		} else {
+			if ((sf = sf_buf_alloc(pg)) == NULL)
+				error = EINTR;
+		}
+		if (sf == NULL) {
 			vm_page_lock_queues();
 			vm_page_unwire(pg, 0);
 			if (pg->wire_count == 0 && pg->object == NULL)
 				vm_page_free(pg);
 			vm_page_unlock_queues();
 			sbunlock(&so->so_snd);
-			error = EINTR;
 			goto done;
 		}
 
-		/*
-		 * Allocate a kernel virtual page and insert the physical page
-		 * into it.
-		 */
-		sf->m = pg;
-		pmap_qenter(sf->kva, &pg, 1);
 		/*
 		 * Get an mbuf header and set it up as having external storage.
 		 */
Index: sys/sys/socketvar.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/socketvar.h,v
retrieving revision 1.102
diff -u -r1.102 socketvar.h
--- sys/sys/socketvar.h	2 Mar 2003 16:54:39 -0000	1.102
+++ sys/sys/socketvar.h	10 Mar 2003 23:29:55 -0000
@@ -316,6 +316,7 @@
 	SLIST_ENTRY(sf_buf) free_list;	/* list of free buffer slots */
 	struct		vm_page *m;	/* currently mapped page */
 	vm_offset_t	kva;		/* va of mapping */
+	int		ref_count;
 };
 
 struct accept_filter {
@@ -371,7 +372,9 @@
 void	sbtoxsockbuf(struct sockbuf *sb, struct xsockbuf *xsb);
 int	sbwait(struct sockbuf *sb);
 struct sf_buf *
-	sf_buf_alloc(void);
+	sf_buf_alloc(struct vm_page *m);
+struct sf_buf *
+	sf_buf_alloc_nb(struct vm_page *m);
 void	sf_buf_free(void *addr, void *args);
 int	sb_lock(struct sockbuf *sb);
 int	soabort(struct socket *so);
Index: sys/vm/vm_page.h
===================================================================
RCS file: /home/ncvs/src/sys/vm/vm_page.h,v
retrieving revision 1.117
diff -u -r1.117 vm_page.h
--- sys/vm/vm_page.h	19 Dec 2002 07:23:46 -0000	1.117
+++ sys/vm/vm_page.h	10 Mar 2003 23:29:55 -0000
@@ -118,6 +118,7 @@
 	vm_pindex_t pindex;		/* offset into object (O,P) */
 	vm_offset_t phys_addr;		/* physical address of page */
 	struct md_page md;		/* machine dependant stuff */
+	struct sf_buf *sf_buf;
 	u_short	queue;			/* page queue index */
 	u_short	flags,			/* see below */
 		pc;			/* page color */