By default, allow up to SSIZE_MAX i/o for non-devfs files.

Sponsored by:	The FreeBSD Foundation
Reminded by:	Dmitry Sivachenko <trtrmitya@gmail.com>
MFC after:	1 month
X-MFC-note:	stable/10 only

sys/kern/sys_generic.c

@@ -75,7 +75,7 @@ __FBSDID("$FreeBSD$");
 
 #include <security/audit/audit.h>
 
-int iosize_max_clamp = 1;
+int iosize_max_clamp = 0;
 SYSCTL_INT(_debug, OID_AUTO, iosize_max_clamp, CTLFLAG_RW,
     &iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX");
 int devfs_iosize_max_clamp = 1;