[XFS] Abstract sendfile operation out, supporting multiple kernels more easily.

SGI Modid: 2.5.x-xfs:slinx:162329a

fs/xfs/linux/xfs_linux.h

@@ -69,6 +69,12 @@
 
 #include <pagebuf/page_buf.h>
 
+/*
+ * Feature macros (disable/enable)
+ */
+#undef  HAVE_REFCACHE	/* reference cache not needed for NFS in 2.6 */
+#define HAVE_SENDFILE	/* sendfile(2) exists in 2.6, but not in 2.4 */
+
 /*
  * State flag for unwritten extent buffers.
  *

fs/xfs/xfs_vnodeops.c

@@ -4767,7 +4767,9 @@ vnodeops_t xfs_vnodeops = {
 	BHV_IDENTITY_INIT(VN_BHV_XFS,VNODE_POSITION_XFS),
 	.vop_open		= xfs_open,
 	.vop_read		= xfs_read,
+#ifdef HAVE_SENDFILE
 	.vop_sendfile		= xfs_sendfile,
+#endif
 	.vop_write		= xfs_write,
 	.vop_ioctl		= xfs_ioctl,
 	.vop_getattr		= xfs_getattr,