Author: kib
Date: Sun Jun 3 16:19:37 2012
New Revision: 236517
URL: http://svn.freebsd.org/changeset/base/236517
Log:
Add a knob to disable vn_io_fault.
MFC after: 1 month
Modified:
head/sys/kern/vfs_vnops.c
Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c Sun Jun 3 16:06:56 2012 (r236516)
+++ head/sys/kern/vfs_vnops.c Sun Jun 3 16:19:37 2012 (r236517)
@@ -697,6 +697,9 @@ unlock:
}
static const int io_hold_cnt = 16;
+static int vn_io_fault_enable = 1;
+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");
@@ -759,7 +762,8 @@ vn_io_fault(struct file *fp, struct uio
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));
/*
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