.\" Copyright (c) 1996 Doug Rabson
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.\" $FreeBSD: src/share/man/man9/VFS_MOUNT.9,v 1.7.2.1 2001/12/17 11:30:18 ru Exp $
.\"
.Dd December 16, 2012
.Dt VFS_MOUNT 9
.Os
.Sh NAME
.Nm VFS_MOUNT
.Nd mount a filesystem
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.In sys/vnode.h
.Ft int
.Fn VFS_MOUNT "struct mount *mp" "char *path" "caddr_t data" "struct ucred *cred"
.Sh DESCRIPTION
Mount a filesystem into the system's namespace.
.Pp
Its arguments are:
.Bl -tag -width data
.It Ar mp
Structure representing the filesystem.
.It Ar path
Pathname where the filesystem is being mounted.
.It Ar data
Filesystem specific data.
This should be read into the kernel using
.Xr copyin 9 .
.It Ar cred
Pointer to a
.Vt struct ucred
for user credentials checking.
.El
.Pp
This is called both to mount new filesystems and to change the
attributes of an existing filesystem.
If the
.Dv MNT_UPDATE
flag is set in
.Fa mp->mnt_flag
then the filesystem should update its internal state from the value of
.Fa mp->mnt_flag .
This can be used, for instance, to convert a read-only filesystem to
read-write.
It is also used by
.Xr mountd 8
to update the NFS export information for the filesystem.
.Pp
If the
.Dv MNT_UPDATE
flag is not specified, then this is a newly mounted filesystem.
The filesystem code should allocate and initialize
any private data needed to represent the filesystem (it can use the
.Fa mp->mnt_data
field to store this information).
.Sh SEE ALSO
.Xr VFS 9 ,
.Xr vnode 9
.Sh AUTHORS
This man page was written by
.An Doug Rabson .