From bad2c3f1c817a94b7638bbf6456ff862829aed76 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Tue, 6 May 2008 15:46:34 -0700
Subject: [PATCH] Enable tests for splice on Linux. Add a static (vl, I hate
 this) so we can detect broken Linux recvfile splice and correctly fall back.
 Karolin, I think this should be pulled into 3.2-stable even though it's a
 feature change as otherwise there's no way for 3.2 to use recvfile zerocopy,
 which is an advertised feature. Others please comment. Jeremy.

---
 source/configure.in   | 20 ++++++++++++++++++++
 source/lib/recvfile.c | 21 +++++++++++++++++++--
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/source/configure.in b/source/configure.in
index a07b5b4aacd..bbce8b65e87 100644
--- a/source/configure.in
+++ b/source/configure.in
@@ -5664,6 +5664,26 @@ if test x"$samba_cv_HAVE_POSIX_FADVISE" = x"yes"; then
              [Whether posix_fadvise is available])
 fi
 
+############################################
+# See if we have the Linux splice syscall.
+
+AC_CACHE_CHECK([for Linux splice],
+                samba_cv_HAVE_LINUX_SPLICE,[
+    AC_TRY_LINK([
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+#include <fcntl.h>],
+    [long ret = splice(0,0,1,0,400,0);],
+    samba_cv_HAVE_LINUX_SPLICE=yes,
+    samba_cv_HAVE_LINUX_SPLICE=no)])
+
+if test x"$samba_cv_HAVE_LINUX_SPLICE" = x"yes"; then
+  AC_DEFINE(HAVE_LINUX_SPLICE,1,
+             [Whether Linux splice is available])
+fi
+
+AC_HAVE_DECL(splice, [#include <fcntl.h>])
 
 
 #################################################
diff --git a/source/lib/recvfile.c b/source/lib/recvfile.c
index f9788fdefb6..6e209333503 100644
--- a/source/lib/recvfile.c
+++ b/source/lib/recvfile.c
@@ -124,7 +124,7 @@ static ssize_t default_sys_recvfile(int fromfd,
 	return (ssize_t)total_written;
 }
 
-#if defined(HAVE_SPLICE_SYSCALL)
+#if defined(HAVE_LINUX_SPLICE)
 
 /*
  * Try and use the Linux system call to do this.
@@ -134,17 +134,33 @@ static ssize_t default_sys_recvfile(int fromfd,
  * from the network in the case of return != -1.
  */
 
+
 ssize_t sys_recvfile(int fromfd,
 			int tofd,
 			SMB_OFF_T offset,
 			size_t count)
 {
+	static bool try_splice_call = true;
 	size_t total_written = 0;
 
 	if (count == 0) {
 		return 0;
 	}
 
+	/*
+	 * Older Linux kernels have splice for sendfile,
+	 * but it fails for recvfile. Ensure we only try
+	 * this once and always fall back to the userspace
+	 * implementation if recvfile splice fails. JRA.
+	 */
+
+	if (!try_splice_call) {
+		return default_sys_recvfile(fromfd,
+				tofd,
+				offset,
+				count);
+	}
+
 	while (total_written < count) {
 		ssize_t ret = splice(fromfd,
 					NULL,
@@ -155,7 +171,8 @@ ssize_t sys_recvfile(int fromfd,
 		if (ret == -1) {
 			if (errno != EINTR) {
 				if (total_written == 0 &&
-						errno == EBADF || errno == EINVAL) {
+						(errno == EBADF || errno == EINVAL)) {
+					try_splice_call = false;
 					return default_sys_recvfile(fromfd,
 								tofd,
 								offset,
-- 
2.34.1