1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
|
.\" $OpenBSD: mount.2,v 1.13 1999/05/23 14:10:55 aaron Exp $
.\" $NetBSD: mount.2,v 1.12 1996/02/29 23:47:48 jtc Exp $
.\"
.\" 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. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. 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 8.2 (Berkeley) 12/11/93
.\"
.Dd December 11, 1993
.Dt MOUNT 2
.Os
.Sh NAME
.Nm mount ,
.Nm unmount
.Nd mount or dismount a filesystem
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <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"
.Sh DESCRIPTION
The
.Fn mount
function grafts
a filesystem object onto the system file tree
at the point
.Ar dir .
The argument
.Ar data
describes the filesystem object to be mounted.
The argument
.Ar type
tells the kernel how to interpret
.Ar data
(See
.Ar type
below).
The contents of the filesystem
become available through the new mount point
.Ar dir .
Any files in
.Ar dir
at the time
of a successful mount are swept under the carpet so to speak, and
are unavailable until the filesystem is unmounted.
.Pp
The following
.Ar flags
may be specified to
suppress default semantics which affect filesystem access.
.Bl -tag -width MNT_SYNCHRONOUS
.It Dv MNT_RDONLY
The filesystem should be treated as read-only;
Even the super-user may not write on it.
.It Dv MNT_NOATIME
Do not update the access time on files in the filesystem unless
the modification or status change times are also being updated.
.It Dv MNT_NOEXEC
Do not allow files to be executed from the filesystem.
.It Dv MNT_NOSUID
Do not honor setuid or setgid bits on files when executing them.
.It Dv MNT_NODEV
Do not interpret special files on the filesystem.
.It Dv MNT_UNION
Union with underlying filesystem instead of obscuring it.
.It Dv MNT_SYNCHRONOUS
All I/O to the filesystem should be done synchronously.
.El
.Pp
The flag
.Dv MNT_UPDATE
indicates that the mount command is being applied
to an already mounted filesystem.
This allows the mount flags to be changed without requiring
that the filesystem be unmounted and remounted.
Some filesystems may not allow all flags to be changed.
For example,
most filesystems will not allow a change from read-write to read-only.
.Pp
The
.Fa type
argument defines the type of the filesystem.
The types of filesystems known to the system are defined in
.Aq Pa sys/mount.h .
.Fa data
is a pointer to a structure that contains the type
specific arguments to mount.
The currently supported types of filesystems and
their type specific data are:
.Pp
.Dv MOUNT_FFS
.Bd -literal -offset indent -compact
struct ufs_args {
char *fspec; /* block special file to mount */
struct export_args export; /* network export information */
};
.Ed
.Pp
.Dv MOUNT_NFS
.Bd -literal -offset indent -compact
struct nfs_args {
int version; /* args structure version */
struct sockaddr *addr; /* file server address */
int addrlen; /* length of address */
int sotype; /* Socket type */
int proto; /* and Protocol */
u_char *fh; /* File handle to be mounted */
int fhsize; /* Size, in bytes, of fh */
int flags; /* flags */
int wsize; /* write size in bytes */
int rsize; /* read size in bytes */
int readdirsize; /* readdir size in bytes */
int timeo; /* initial timeout in .1 secs */
int retrans; /* times to retry send */
int maxgrouplist; /* Max. size of group list */
int readahead; /* # of blocks to readahead */
int leaseterm; /* Term (sec) of lease */
int deadthresh; /* Retrans threshold */
char *hostname; /* server's name */
};
.Ed
.Pp
.Dv MOUNT_MFS
.Bd -literal -offset indent -compact
struct mfs_args {
char *fspec; /* name to export for statfs */
struct export_args export; /* if we can export an MFS */
caddr_t base; /* base of filesystem in mem */
u_long size; /* size of filesystem */
};
.Ed
.Pp
The
.Fn unmount
function call disassociates the filesystem from the specified
mount point
.Fa dir .
.Pp
The
.Fa flags
argument may specify
.Dv MNT_FORCE
to specify that the filesystem 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 filesystem is later remounted.
.Sh RETURN VALUES
The
.Fn mount
returns the value 0 if the mount was successful, otherwise -1 is returned
and the variable
.Va errno
is set to indicate the error.
.Pp
.Fn unmount
returns the value 0 if the unmount succeeded; otherwise -1 is returned
and the variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn mount
will fail when one of the following occurs:
.Bl -tag -width [ENAMETOOLONG]
.It Bq Er EPERM
The caller is not the super-user.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Dv {NAME_MAX}
characters, or an entire path name exceeded
.Dv {PATH_MAX}
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
.Ar name
is not a directory,
or a path prefix of
.Ar special
is not a directory.
.It Bq Er EINVAL
A pathname contains a character with the high-order bit set.
.It Bq Er EBUSY
Another process currently holds a reference to
.Fa dir .
.It Bq Er EFAULT
.Fa dir
points outside the process's allocated address space.
.It Bq Er EOPNOTSUPP
.Fa type
is not supported by the kernel.
.El
.Pp
The following errors can occur for a
.Em ufs
filesystem mount:
.Bl -tag -width [ENOTBLK]
.It Bq Er ENODEV
A component of ufs_args
.Ar fspec
does not exist.
.It Bq Er ENOTBLK
.Ar Fspec
is not a block device.
.It Bq Er ENXIO
The major device number of
.Ar fspec
is out of range (this indicates no device driver exists
for the associated hardware).
.It Bq Er EBUSY
.Ar Fspec
is already mounted.
.It Bq Er EMFILE
No space remains in the mount table.
.It Bq Er EINVAL
The super block for the filesystem 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 filesystem.
.It Bq Er EIO
An I/O error occurred while reading the super block or
cylinder group information.
.It Bq Er EFAULT
.Ar Fspec
points outside the process's allocated address space.
.El
.Pp
The following errors can occur for a
.Em nfs
filesystem mount:
.Bl -tag -width [ETIMEDOUT]
.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 following errors can occur for a
.Em mfs
filesystem mount:
.Bl -tag -width [EMFILE]
.It Bq Er EMFILE
No space remains in the mount table.
.It Bq Er EINVAL
The super block for the filesystem 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 filesystem.
.It Bq Er EIO
A paging error occurred while reading the super block or
cylinder group information.
.It Bq Er EFAULT
.Em Name
points outside the process's allocated address space.
.El
.Pp
.Fn unmount
may fail with one of the following errors:
.Bl -tag -width [ENAMETOOLONG]
.It Bq Er EPERM
The caller is not the super-user.
.It Bq Er ENOTDIR
A component of the path is not a directory.
.It Bq Er EINVAL
The pathname contains a character with the high-order bit set.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Dv {NAME_MAX}
characters, or an entire path name exceeded
.Dv {PATH_MAX}
characters.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EINVAL
The requested directory is not in the mount table.
.It Bq Er EBUSY
A process is holding a reference to a file located
on the filesystem.
.It Bq Er EIO
An I/O error occurred while writing cached filesystem information.
.It Bq Er EFAULT
.Fa dir
points outside the process's allocated address space.
.El
.Pp
A
.Em ufs
or
.Em mfs
mount can also fail if the maximum number of filesystems are currently
mounted.
.Sh SEE ALSO
.Xr statfs 2 ,
.Xr mfs 8 ,
.Xr mount 8 ,
.Xr umount 8
.Sh BUGS
Some of the error codes need translation to more obvious messages.
.Sh HISTORY
.Fn mount
and
.Fn unmount
function calls appeared in
.At v6 .
|