1.\" $OpenBSD: mount.2,v 1.50 2021/01/03 18:10:27 rob Exp $ 2.\" $NetBSD: mount.2,v 1.12 1996/02/29 23:47:48 jtc Exp $ 3.\" 4.\" Copyright (c) 1980, 1989, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)mount.2 8.2 (Berkeley) 12/11/93 32.\" 33.Dd $Mdocdate: January 3 2021 $ 34.Dt MOUNT 2 35.Os 36.Sh NAME 37.Nm mount , 38.Nm unmount 39.Nd mount or dismount a filesystem 40.Sh SYNOPSIS 41.In sys/types.h 42.In sys/mount.h 43.Ft int 44.Fn mount "const char *type" "const char *dir" "int flags" "void *data" 45.Ft int 46.Fn unmount "const char *dir" "int flags" 47.Sh DESCRIPTION 48The 49.Fn mount 50function grafts 51a filesystem object onto the system file tree 52at the point 53.Fa dir . 54The argument 55.Fa data 56describes the filesystem object to be mounted. 57The argument 58.Fa type 59tells the kernel how to interpret 60.Fa data 61(see 62.Fa type 63below). 64The contents of the filesystem 65become available through the new mount point 66.Fa dir . 67Any files in 68.Fa dir 69at the time 70of a successful mount are swept under the carpet, so to speak, and 71are unavailable until the filesystem is unmounted. 72.Pp 73The following 74.Fa flags 75may be specified to 76suppress default semantics which affect filesystem access. 77.Bl -tag -width MNT_SYNCHRONOUS 78.It Dv MNT_RDONLY 79The filesystem should be treated as read-only: 80even the superuser may not write to it. 81.It Dv MNT_NOATIME 82Do not update the access time on files in the filesystem unless 83the modification or status change times are also being updated. 84.It Dv MNT_NOEXEC 85Do not allow files to be executed from the filesystem. 86.It Dv MNT_NOSUID 87Do not honor setuid or setgid bits on files when executing them. 88.It Dv MNT_NODEV 89Do not interpret special files on the filesystem. 90.It Dv MNT_SYNCHRONOUS 91All I/O to the filesystem should be done synchronously. 92.It Dv MNT_ASYNC 93All I/O to the filesystem should be done asynchronously. 94.It Dv MNT_SOFTDEP 95Use soft dependencies. 96Applies to FFS filesystems only (see 'softdep' in 97.Xr mount 8 ) . 98.It Dv MNT_WXALLOWED 99Processes that ask for memory to be made writeable plus executable 100using the 101.Xr mmap 2 102and 103.Xr mprotect 2 104system calls are killed by default. 105This option allows those processes to continue operation. 106The option is typically used on the 107.Pa /usr/local 108filesystem. 109.El 110.Pp 111The flag 112.Dv MNT_UPDATE 113indicates that the mount command is being applied 114to an already mounted filesystem. 115This allows the mount flags to be changed without requiring 116that the filesystem be unmounted and remounted. 117Some filesystems may not allow all flags to be changed. 118For example, 119most filesystems will not allow a change from read-write to read-only. 120.Pp 121The 122.Fa type 123argument defines the type of the filesystem. 124The types of filesystems known to the system are defined in 125.In sys/mount.h . 126.Fa data 127is a pointer to a structure that contains the type 128specific arguments to mount. 129The currently supported types of filesystems and 130their type specific data are: 131.Pp 132.Dv MOUNT_CD9660 133.Bd -literal -offset indent -compact 134struct iso_args { 135 char *fspec; /* block special device to mount */ 136 struct export_args export_info; 137 /* network export info */ 138 int flags; /* mounting flags, see below */ 139}; 140#define ISOFSMNT_NORRIP 0x00000001 /* disable Rock Ridge Ext.*/ 141#define ISOFSMNT_GENS 0x00000002 /* enable generation numbers */ 142#define ISOFSMNT_EXTATT 0x00000004 /* enable extended attributes */ 143#define ISOFSMNT_NOJOLIET 0x00000008 /* disable Joliet Ext.*/ 144#define ISOFSMNT_SESS 0x00000010 /* use iso_args.sess */ 145.Ed 146.Pp 147.Dv MOUNT_FFS 148.Bd -literal -offset indent -compact 149struct ufs_args { 150 char *fspec; /* block special file to mount */ 151 struct export_args export_info; 152 /* network export information */ 153}; 154.Ed 155.Pp 156.Dv MOUNT_MFS 157.Bd -literal -offset indent -compact 158struct mfs_args { 159 char *fspec; /* name to export for statfs */ 160 struct export_args export_info; 161 /* if we can export an MFS */ 162 caddr_t base; /* base of filesystem in mem */ 163 u_long size; /* size of filesystem */ 164}; 165.Ed 166.Pp 167.Dv MOUNT_MSDOS 168.Bd -literal -offset indent -compact 169struct msdosfs_args { 170 char *fspec; /* blocks special holding fs to mount */ 171 struct export_args export_info; 172 /* network export information */ 173 uid_t uid; /* uid that owns msdosfs files */ 174 gid_t gid; /* gid that owns msdosfs files */ 175 mode_t mask; /* mask to be applied for msdosfs perms */ 176 int flags; /* see below */ 177}; 178 179/* 180 * Msdosfs mount options: 181 */ 182#define MSDOSFSMNT_SHORTNAME 1 /* Force old DOS short names only */ 183#define MSDOSFSMNT_LONGNAME 2 /* Force Win'95 long names */ 184#define MSDOSFSMNT_NOWIN95 4 /* Completely ignore Win95 entries */ 185.Ed 186.Pp 187.Dv MOUNT_NFS 188.Bd -literal -offset indent -compact 189struct nfs_args { 190 int version; /* args structure version */ 191 struct sockaddr *addr; /* file server address */ 192 int addrlen; /* length of address */ 193 int sotype; /* Socket type */ 194 int proto; /* and Protocol */ 195 u_char *fh; /* File handle to be mounted */ 196 int fhsize; /* Size, in bytes, of fh */ 197 int flags; /* flags */ 198 int wsize; /* write size in bytes */ 199 int rsize; /* read size in bytes */ 200 int readdirsize; /* readdir size in bytes */ 201 int timeo; /* initial timeout in .1 secs */ 202 int retrans; /* times to retry send */ 203 int maxgrouplist; /* Max. size of group list */ 204 int readahead; /* # of blocks to readahead */ 205 int leaseterm; /* Term (sec) of lease */ 206 int deadthresh; /* Retrans threshold */ 207 char *hostname; /* server's name */ 208 int acregmin; /* Attr cache file recently modified */ 209 int acregmax; /* ac file not recently modified */ 210 int acdirmin; /* ac for dir recently modified */ 211 int acdirmax; /* ac for dir not recently modified */ 212}; 213.Ed 214.Pp 215.Dv MOUNT_NTFS 216.Bd -literal -offset indent -compact 217struct ntfs_args { 218 char *fspec; /* block special device to mount */ 219 struct export_args export_info; 220 /* network export information */ 221 uid_t uid; /* uid that owns ntfs files */ 222 gid_t gid; /* gid that owns ntfs files */ 223 mode_t mode; /* mask to be applied for ntfs perms */ 224 u_long flag; /* additional flags */ 225}; 226 227/* 228 * ntfs mount options: 229 */ 230#define NTFS_MFLAG_CASEINS 0x00000001 231#define NTFS_MFLAG_ALLNAMES 0x00000002 232.Ed 233.Pp 234.Dv MOUNT_UDF 235.Bd -literal -offset indent -compact 236struct udf_args { 237 char *fspec; /* block special device to mount */ 238}; 239.Ed 240.Pp 241The 242.Fn unmount 243function call disassociates the filesystem from the specified 244mount point 245.Fa dir . 246.Pp 247The 248.Fa flags 249argument may specify 250.Dv MNT_FORCE 251to specify that the filesystem should be forcibly unmounted even if files are 252still active. 253Active special devices continue to work, 254but any further accesses to any other active files result in errors 255even if the filesystem is later remounted. 256.Sh RETURN VALUES 257.Rv -std 258.Sh ERRORS 259.Fn mount 260will fail when one of the following occurs: 261.Bl -tag -width [ENAMETOOLONG] 262.It Bq Er EPERM 263The caller is not the superuser. 264.It Bq Er ENAMETOOLONG 265The pathname exceeded 266.Dv MNAMELEN 267characters. 268.It Bq Er ELOOP 269Too many symbolic links were encountered in translating a pathname. 270.It Bq Er ENOENT 271A component of 272.Fa dir 273does not exist. 274.It Bq Er ENOTDIR 275A component of 276.Ar name 277is not a directory, 278or a path prefix of 279.Ar special 280is not a directory. 281.It Bq Er EINVAL 282An argument given was invalid. 283.It Bq Er EBUSY 284Another process currently holds a reference to 285.Fa dir . 286.It Bq Er EFAULT 287.Fa dir 288points outside the process's allocated address space. 289.It Bq Er EOPNOTSUPP 290.Fa type 291is not supported by the kernel. 292.El 293.Pp 294The following errors can occur for a 295.Dq ufs 296filesystem mount: 297.Bl -tag -width [ENOTBLK] 298.It Bq Er ENODEV 299A component of ufs_args 300.Fa fspec 301does not exist. 302.It Bq Er ENOTBLK 303.Fa fspec 304is not a block device. 305.It Bq Er ENXIO 306The major device number of 307.Fa fspec 308is out of range (this indicates no device driver exists 309for the associated hardware). 310.It Bq Er EBUSY 311.Fa fspec 312is already mounted. 313.It Bq Er EINVAL 314The super block for the filesystem had a bad magic number, an out of range 315block size, or an invalid combination of flags. 316.It Bq Er ENOMEM 317Not enough memory was available to read the cylinder 318group information for the filesystem. 319.It Bq Er EIO 320An I/O error occurred while reading the super block or 321cylinder group information. 322.It Bq Er EFAULT 323.Fa fspec 324points outside the process's allocated address space. 325.It Bq Er EROFS 326The filesystem was not unmounted cleanly and 327.Dv MNT_FORCE 328was not specified. 329.It Bq Er EROFS 330An attempt was made to mount a 331.Bx 4.2 332filesystem without the 333.Dv MNT_RDONLY 334flag. 335.El 336.Pp 337The following errors can occur for an 338.Em NFS 339filesystem mount: 340.Bl -tag -width [ETIMEDOUT] 341.It Bq Er ETIMEDOUT 342.Em NFS 343timed out trying to contact the server. 344.It Bq Er EFAULT 345Some part of the information described by nfs_args 346points outside the process's allocated address space. 347.El 348.Pp 349The following errors can occur for a 350.Em mfs 351filesystem mount: 352.Bl -tag -width [EMFILE] 353.It Bq Er EMFILE 354No space remains in the mount table. 355.It Bq Er EINVAL 356The super block for the filesystem had a bad magic 357number or an out of range block size. 358.It Bq Er ENOMEM 359Not enough memory was available to read the cylinder 360group information for the filesystem. 361.It Bq Er EIO 362A paging error occurred while reading the super block or 363cylinder group information. 364.It Bq Er EFAULT 365.Em Name 366points outside the process's allocated address space. 367.El 368.Pp 369.Fn unmount 370may fail with one of the following errors: 371.Bl -tag -width [ENAMETOOLONG] 372.It Bq Er EPERM 373The caller is not the superuser. 374.It Bq Er ENOTDIR 375A component of the path is not a directory. 376.It Bq Er EINVAL 377An argument given was invalid. 378.It Bq Er ENAMETOOLONG 379A component of a pathname exceeded 380.Dv NAME_MAX 381characters, or an entire pathname (including the terminating NUL) 382exceeded 383.Dv PATH_MAX 384bytes. 385.It Bq Er ELOOP 386Too many symbolic links were encountered in translating the pathname. 387.It Bq Er EINVAL 388The requested directory is not in the mount table. 389.It Bq Er EBUSY 390A process is holding a reference to a file located 391on the filesystem. 392.It Bq Er EIO 393An I/O error occurred while writing cached filesystem information. 394.It Bq Er EFAULT 395.Fa dir 396points outside the process's allocated address space. 397.El 398.Sh SEE ALSO 399.Xr statfs 2 , 400.Xr mount 8 , 401.Xr mount_mfs 8 , 402.Xr umount 8 403.Sh HISTORY 404The 405.Fn mount 406and 407.Fn unmount 408system calls first appeared in 409.At v1 . 410The 411.Fa flags 412argument is supported by 413.Fn mount 414since 415.At v5 416and by 417.Fn unmount 418since 419.Bx 4.3 Reno . 420The current calling convention involving 421.Fa type 422and 423.Fa data 424arguments was introduced by 425.Bx 4.3 Reno 426as well. 427.Sh BUGS 428Some of the error codes need translation to more obvious messages. 429