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Add a knob to disable vn_io_fault.

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MFC after:	1 month
This commit is contained in:
Konstantin Belousov 2012-06-03 16:19:37 +00:00
parent bb2f52a61d
commit bba080854d
1 changed files with 5 additions and 1 deletions
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6
sys/kern/vfs_vnops.c
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@ -697,6 +697,9 @@ vn_write(fp, uio, active_cred, flags, td)
}
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 *uio, struct ucred *active_cred,
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));
/*