Provided by: freebsd-manpages_12.2-1_all 

NAME
vfs_busy — marks a mount point as busy
SYNOPSIS
#include <sys/param.h>
#include <sys/mount.h>
int
vfs_busy(struct mount *mp, int flags);
DESCRIPTION
The 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 mp if the MNTK_UNMOUNT flag is set in mp->mnt_kern_flag and the
MBF_NOWAIT flag is not set.
Its arguments are:
mp The mount point to busy.
flags Flags controlling how vfs_busy() should act.
MBF_NOWAIT do not sleep if MNTK_UNMOUNT is set.
MBF_MNTLSTLOCK drop the mountlist_mtx in the critical path.
RETURN VALUES
A 0 value is returned on success. If the mount point is being unmounted and MBF_NOWAIT flag is specified
ENOENT will be returned.
ERRORS
[ENOENT] The mount point is being unmounted (MNTK_UNMOUNT is set).
SEE ALSO
vfs_unbusy(9)
AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>.
Debian February 11, 2013 VFS_BUSY(9)