- Enable SMP VFS by default on current. More users are needed to turn up

any remaining bugs.  Anyone inconvenienced by this can still disable it
   in the loader.

Sponsored by:	Isilon Systems, Inc.

sys/kern/vfs_subr.c

@@ -98,7 +98,11 @@ static void	vholdl(struct vnode *);
  * Enable Giant pushdown based on whether or not the vm is mpsafe in this
  * build.  Without mpsafevm the buffer cache can not run Giant free.
  */
-int mpsafe_vfs = 0;
+#if defined(__alpha__) || defined(__amd64__) || defined(__i386__)
+int mpsafe_vfs = 1;
+#else
+int mpsafe_vfs;
+#endif
 TUNABLE_INT("debug.mpsafevfs", &mpsafe_vfs);
 SYSCTL_INT(_debug, OID_AUTO, mpsafevfs, CTLFLAG_RD, &mpsafe_vfs, 0,
     "MPSAFE VFS");