[Midnightbsd-cvs] src [7927] trunk/sys/kern/vfs_vnops.c: add a knob to disable vn_io_fault

[laffer1 at midnightbsd.org]

Revision: 7927
          http://svnweb.midnightbsd.org/src/?rev=7927
Author:   laffer1
Date:     2016-09-14 17:03:18 -0400 (Wed, 14 Sep 2016)
Log Message:
-----------
add a knob to disable vn_io_fault

Modified Paths:
--------------
    trunk/sys/kern/vfs_vnops.c

Modified: trunk/sys/kern/vfs_vnops.c
===================================================================
--- trunk/sys/kern/vfs_vnops.c	2016-09-14 21:00:38 UTC (rev 7926)
+++ trunk/sys/kern/vfs_vnops.c	2016-09-14 21:03:18 UTC (rev 7927)
@@ -767,6 +767,9 @@
 }
 
 static const int io_hold_cnt = 16;
+static int vn_io_fault_enable = 0;
+SYSCTL_INT(_debug, OID_AUTO, vn_io_fault_enable, CTLFLAG_RW,
+    &vn_io_fault_enable, 0, "Enable vn_io_fault lock avoidance");
 static unsigned long vn_io_faults_cnt;
 SYSCTL_LONG(_debug, OID_AUTO, vn_io_faults, CTLFLAG_RD,
     &vn_io_faults_cnt, 0, "Count of vn_io_fault lock avoidance triggers");
@@ -829,7 +832,8 @@
 	vp = fp->f_vnode;
 	if (uio->uio_segflg != UIO_USERSPACE || vp->v_type != VREG ||
 	    ((mp = vp->v_mount) != NULL &&
-	    (mp->mnt_kern_flag & MNTK_NO_IOPF) == 0))
+	    (mp->mnt_kern_flag & MNTK_NO_IOPF) == 0) ||
+	    !vn_io_fault_enable)
 		return (doio(fp, uio, active_cred, flags, td));
 
 	/*