.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice(s), this list of conditions and the following disclaimer as
.\"    the first lines of this file unmodified other than the possible
.\"    addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice(s), this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd February 11, 2013
.Dt VFS_BUSY 9
.Os
.Sh NAME
.Nm vfs_busy
.Nd "marks a mount point as busy"
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.Ft int
.Fn vfs_busy "struct mount *mp" "int flags"
.Sh DESCRIPTION
The
.Fn vfs_busy
function marks a mount point as busy by incrementing
the reference count of a mount point.
It also delays unmounting by sleeping on
.Fa mp
if the
.Dv MNTK_UNMOUNT
flag is set in
.Fa mp->mnt_kern_flag
and the
.Dv MBF_NOWAIT
flag is
.Em not
set.
.Pp
Its arguments are:
.Bl -tag -width ".Fa flags"
.It Fa mp
The mount point to busy.
.It Fa flags
Flags controlling how
.Fn vfs_busy
should act.
.Bl -tag -width ".Dv MBF_MNTLSTLOCK"
.It Dv MBF_NOWAIT
do not sleep if
.Dv MNTK_UNMOUNT
is set.
.It Dv MBF_MNTLSTLOCK
drop the mountlist_mtx in the critical path.
.El
.El
.Sh RETURN VALUES
A 0 value is returned on success.
If the mount point is being
unmounted and MBF_NOWAIT flag is specified
.Er ENOENT
will be returned.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOENT
The mount point is being unmounted
.Dv ( MNTK_UNMOUNT
is set).
.El
.Sh SEE ALSO
.Xr vfs_unbusy 9
.Sh AUTHORS
This manual page was written by
.An Chad David Aq davidc@acns.ab.ca .