mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-22 11:17:19 +00:00
aeb71118e6
HISTORY section. Note: Any system calls that were added prior to v7, but after v1 weren't changed. Obtained from: http://www.tuhs.org/cgi-bin/utree.pl?file=V1/man/man2
379 lines
10 KiB
Groff
379 lines
10 KiB
Groff
.\" Copyright (c) 1980, 1989, 1993
|
|
.\" The Regents of the University of California. 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, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
|
|
.\"
|
|
.\" @(#)mount.2 8.3 (Berkeley) 5/24/95
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd December 1, 2017
|
|
.Dt MOUNT 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm mount ,
|
|
.Nm nmount ,
|
|
.Nm unmount
|
|
.Nd mount or dismount a file system
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/param.h
|
|
.In sys/mount.h
|
|
.Ft int
|
|
.Fn mount "const char *type" "const char *dir" "int flags" "void *data"
|
|
.Ft int
|
|
.Fn unmount "const char *dir" "int flags"
|
|
.In sys/uio.h
|
|
.Ft int
|
|
.Fn nmount "struct iovec *iov" "u_int niov" "int flags"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn mount
|
|
system call grafts
|
|
a file system object onto the system file tree
|
|
at the point
|
|
.Fa dir .
|
|
The argument
|
|
.Fa data
|
|
describes the file system object to be mounted.
|
|
The argument
|
|
.Fa type
|
|
tells the kernel how to interpret
|
|
.Fa data
|
|
(See
|
|
.Fa type
|
|
below).
|
|
The contents of the file system
|
|
become available through the new mount point
|
|
.Fa dir .
|
|
Any files in
|
|
.Fa dir
|
|
at the time
|
|
of a successful mount are swept under the carpet so to speak, and
|
|
are unavailable until the file system is unmounted.
|
|
.Pp
|
|
The
|
|
.Fn nmount
|
|
system call behaves similarly to
|
|
.Fn mount ,
|
|
except that the mount options (file system type name, device to mount,
|
|
mount-point name, etc.) are passed as an array of name-value pairs
|
|
in the array
|
|
.Fa iov ,
|
|
containing
|
|
.Fa niov
|
|
elements.
|
|
The following options are required by all file systems:
|
|
.Bl -column fstype -offset indent
|
|
.It
|
|
.Li fstype Ta file system type name (e.g., Dq Li procfs )
|
|
.It
|
|
.Li fspath Ta mount point pathname (e.g., Dq Li /proc )
|
|
.El
|
|
.Pp
|
|
Depending on the file system type, other options may be
|
|
recognized or required;
|
|
for example, most disk-based file systems require a
|
|
.Dq Li from
|
|
option containing the pathname of a special device
|
|
in addition to the options listed above.
|
|
.Pp
|
|
By default only the super-user may call the
|
|
.Fn mount
|
|
system call.
|
|
This restriction can be removed by setting the
|
|
.Va vfs.usermount
|
|
.Xr sysctl 8
|
|
variable
|
|
to a non-zero value; see the BUGS section for more information.
|
|
.Pp
|
|
The following
|
|
.Fa flags
|
|
may be specified to
|
|
suppress default semantics which affect file system access.
|
|
.Bl -tag -width MNT_SYNCHRONOUS
|
|
.It Dv MNT_RDONLY
|
|
The file system should be treated as read-only;
|
|
even the super-user may not write on it.
|
|
Specifying MNT_UPDATE without this option will upgrade
|
|
a read-only file system to read/write.
|
|
.It Dv MNT_NOEXEC
|
|
Do not allow files to be executed from the file system.
|
|
.It Dv MNT_NOSUID
|
|
Do not honor setuid or setgid bits on files when executing them.
|
|
This flag is set automatically when the caller is not the super-user.
|
|
.It Dv MNT_NOATIME
|
|
Disable update of file access times.
|
|
.It Dv MNT_SNAPSHOT
|
|
Create a snapshot of the file system.
|
|
This is currently only supported on UFS2 file systems, see
|
|
.Xr mksnap_ffs 8
|
|
for more information.
|
|
.It Dv MNT_SUIDDIR
|
|
Directories with the SUID bit set chown new files to their own owner.
|
|
This flag requires the SUIDDIR option to have been compiled into the kernel
|
|
to have any effect.
|
|
See the
|
|
.Xr mount 8
|
|
and
|
|
.Xr chmod 2
|
|
pages for more information.
|
|
.It Dv MNT_SYNCHRONOUS
|
|
All I/O to the file system should be done synchronously.
|
|
.It Dv MNT_ASYNC
|
|
All I/O to the file system should be done asynchronously.
|
|
.It Dv MNT_FORCE
|
|
Force a read-write mount even if the file system appears to be unclean.
|
|
Dangerous.
|
|
Together with
|
|
.Dv MNT_UPDATE
|
|
and
|
|
.Dv MNT_RDONLY ,
|
|
specify that the file system is to be forcibly downgraded to a read-only
|
|
mount even if some files are open for writing.
|
|
.It Dv MNT_NOCLUSTERR
|
|
Disable read clustering.
|
|
.It Dv MNT_NOCLUSTERW
|
|
Disable write clustering.
|
|
.El
|
|
.Pp
|
|
The flag
|
|
.Dv MNT_UPDATE
|
|
indicates that the mount command is being applied
|
|
to an already mounted file system.
|
|
This allows the mount flags to be changed without requiring
|
|
that the file system be unmounted and remounted.
|
|
Some file systems may not allow all flags to be changed.
|
|
For example,
|
|
many file systems will not allow a change from read-write to read-only.
|
|
.Pp
|
|
The flag
|
|
.Dv MNT_RELOAD
|
|
causes the vfs subsystem to update its data structures pertaining to
|
|
the specified already mounted file system.
|
|
.Pp
|
|
The
|
|
.Fa type
|
|
argument names the file system.
|
|
The types of file systems known to the system can be obtained with
|
|
.Xr lsvfs 1 .
|
|
.Pp
|
|
The
|
|
.Fa data
|
|
argument
|
|
is a pointer to a structure that contains the type
|
|
specific arguments to mount.
|
|
The format for these argument structures is described in the
|
|
manual page for each file system.
|
|
By convention file system manual pages are named
|
|
by prefixing ``mount_'' to the name of the file system as returned by
|
|
.Xr lsvfs 1 .
|
|
Thus the
|
|
.Tn NFS
|
|
file system is described by the
|
|
.Xr mount_nfs 8
|
|
manual page.
|
|
It should be noted that a manual page for default
|
|
file systems, known as UFS and UFS2, does not exist.
|
|
.Pp
|
|
The
|
|
.Fn unmount
|
|
system call disassociates the file system from the specified
|
|
mount point
|
|
.Fa dir .
|
|
.Pp
|
|
The
|
|
.Fa flags
|
|
argument may include
|
|
.Dv MNT_FORCE
|
|
to specify that the file system should be forcibly unmounted
|
|
even if files are still active.
|
|
Active special devices continue to work,
|
|
but any further accesses to any other active files result in errors
|
|
even if the file system is later remounted.
|
|
.Pp
|
|
If the
|
|
.Dv MNT_BYFSID
|
|
flag is specified,
|
|
.Fa dir
|
|
should instead be a file system ID encoded as
|
|
.Dq Li FSID : Ns Ar val0 : Ns Ar val1 ,
|
|
where
|
|
.Ar val0
|
|
and
|
|
.Ar val1
|
|
are the contents of the
|
|
.Vt fsid_t
|
|
.Va val[]
|
|
array in decimal.
|
|
The file system that has the specified file system ID will be unmounted.
|
|
.Sh RETURN VALUES
|
|
.Rv -std
|
|
.Sh ERRORS
|
|
The
|
|
.Fn mount
|
|
and
|
|
.Fn nmount
|
|
system calls will fail when one of the following occurs:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EPERM
|
|
The caller is neither the super-user nor the owner of
|
|
.Fa dir .
|
|
.It Bq Er ENAMETOOLONG
|
|
A component of a pathname exceeded 255 characters,
|
|
or the entire length of a path name exceeded 1023 characters.
|
|
.It Bq Er ELOOP
|
|
Too many symbolic links were encountered in translating a pathname.
|
|
.It Bq Er ENOENT
|
|
A component of
|
|
.Fa dir
|
|
does not exist.
|
|
.It Bq Er ENOTDIR
|
|
A component of
|
|
.Fa name
|
|
is not a directory,
|
|
or a path prefix of
|
|
.Fa special
|
|
is not a directory.
|
|
.It Bq Er EBUSY
|
|
Another process currently holds a reference to
|
|
.Fa dir .
|
|
.It Bq Er EFAULT
|
|
The
|
|
.Fa dir
|
|
argument
|
|
points outside the process's allocated address space.
|
|
.El
|
|
.Pp
|
|
The following errors can occur for a
|
|
.Em ufs
|
|
file system mount:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENODEV
|
|
A component of ufs_args
|
|
.Fa fspec
|
|
does not exist.
|
|
.It Bq Er ENOTBLK
|
|
The
|
|
.Fa fspec
|
|
argument
|
|
is not a block device.
|
|
.It Bq Er ENXIO
|
|
The major device number of
|
|
.Fa fspec
|
|
is out of range (this indicates no device driver exists
|
|
for the associated hardware).
|
|
.It Bq Er EBUSY
|
|
.Fa fspec
|
|
is already mounted.
|
|
.It Bq Er EMFILE
|
|
No space remains in the mount table.
|
|
.It Bq Er EINVAL
|
|
The super block for the file system had a bad magic
|
|
number or an out of range block size.
|
|
.It Bq Er ENOMEM
|
|
Not enough memory was available to read the cylinder
|
|
group information for the file system.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading the super block or
|
|
cylinder group information.
|
|
.It Bq Er EFAULT
|
|
The
|
|
.Fa fspec
|
|
argument
|
|
points outside the process's allocated address space.
|
|
.El
|
|
.Pp
|
|
The following errors can occur for a
|
|
.Em nfs
|
|
file system mount:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ETIMEDOUT
|
|
.Em Nfs
|
|
timed out trying to contact the server.
|
|
.It Bq Er EFAULT
|
|
Some part of the information described by nfs_args
|
|
points outside the process's allocated address space.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn unmount
|
|
system call may fail with one of the following errors:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EPERM
|
|
The caller is neither the super-user nor the user who issued the corresponding
|
|
.Fn mount
|
|
call.
|
|
.It Bq Er ENAMETOOLONG
|
|
The length of the path name exceeded 1023 characters.
|
|
.It Bq Er EINVAL
|
|
The requested directory is not in the mount table.
|
|
.It Bq Er ENOENT
|
|
The file system ID specified using
|
|
.Dv MNT_BYFSID
|
|
was not found in the mount table.
|
|
.It Bq Er EINVAL
|
|
The file system ID specified using
|
|
.Dv MNT_BYFSID
|
|
could not be decoded.
|
|
.It Bq Er EINVAL
|
|
The specified file system is the root file system.
|
|
.It Bq Er EBUSY
|
|
A process is holding a reference to a file located
|
|
on the file system.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while writing cached file system information.
|
|
.It Bq Er EFAULT
|
|
The
|
|
.Fa dir
|
|
argument
|
|
points outside the process's allocated address space.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr lsvfs 1 ,
|
|
.Xr mksnap_ffs 8 ,
|
|
.Xr mount 8 ,
|
|
.Xr umount 8
|
|
.Sh HISTORY
|
|
The
|
|
.Fn mount
|
|
and
|
|
.Fn unmount
|
|
functions appeared in
|
|
.At v1 .
|
|
The
|
|
.Fn nmount
|
|
system call first appeared in
|
|
.Fx 5.0 .
|
|
.Sh BUGS
|
|
Some of the error codes need translation to more obvious messages.
|
|
.Pp
|
|
Allowing untrusted users to mount arbitrary media, e.g. by enabling
|
|
.Va vfs.usermount ,
|
|
should not be considered safe.
|
|
Most file systems in
|
|
.Fx
|
|
were not built to safeguard against malicious devices.
|