MOUNT(2) BSD Programmer's Manual MOUNT(2)NAME
mount, unmount - mount or dismount a filesystem
SYNOPSIS
#include <sys/param.h>
#include <sys/mount.h>
int
mount(const char *type, const char *dir, int flags, void *data);
int
unmount(const char *dir, int flags);
DESCRIPTION
The mount() function grafts a filesystem object onto the system file tree
at the point dir. The argument data describes the filesystem object to be
mounted. The argument type tells the kernel how to interpret data (see
type below). The contents of the filesystem become available through the
new mount point dir. Any files in dir at the time of a successful mount
are swept under the carpet, so to speak, and are unavailable until the
filesystem is unmounted.
The following flags may be specified to suppress default semantics which
affect filesystem access.
MNT_RDONLY The filesystem should be treated as read-only: even the
superuser may not write to it.
MNT_NOATIME Do not update the access time on files in the filesystem
unless the modification or status change times are also
being updated.
MNT_NOEXEC Do not allow files to be executed from the filesystem.
MNT_NOSUID Do not honor setuid or setgid bits on files when execut-
ing them.
MNT_NODEV Do not interpret special files on the filesystem.
MNT_SYNCHRONOUS All I/O to the filesystem should be done synchronously.
MNT_ASYNC All I/O to the filesystem should be done asynchronously.
MNT_SOFTDEP Use soft dependencies. Applies to FFS filesystems only
(see 'softdep' in mount(8)).
The flag 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.
The type argument defines the type of the filesystem. The types of
filesystems known to the system are defined in <sys/mount.h>. 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:
MOUNT_ADOSFS
struct adosfs_args {
char *fspec; /* blocks special holding fs to mount */
struct export_args export_info;
/* network export information */
uid_t uid; /* uid that owns adosfs files */
gid_t gid; /* gid that owns adosfs files */
mode_t mask; /* mask to be applied for adosfs perms */
};
MOUNT_CD9660
struct iso_args {
char *fspec; /* block special device to mount */
struct export_args export_info;
/* network export info */
int flags; /* mounting flags, see below */
};
#define ISOFSMNT_NORRIP 0x00000001 /* disable Rock Ridge Ext.*/
#define ISOFSMNT_GENS 0x00000002 /* enable generation numbers */
#define ISOFSMNT_EXTATT 0x00000004 /* enable extended attributes */
#define ISOFSMNT_NOJOLIET 0x00000008 /* disable Joliet Ext.*/
MOUNT_FFS
struct ufs_args {
char *fspec; /* block special file to mount */
struct export_args export_info;
/* network export information */
};
MOUNT_MFS
struct mfs_args {
char *fspec; /* name to export for statfs */
struct export_args export_info;
/* if we can export an MFS */
caddr_t base; /* base of filesystem in mem */
u_long size; /* size of filesystem */
};
MOUNT_MSDOS
struct msdosfs_args {
char *fspec; /* blocks special holding fs to mount */
struct export_args export_info;
/* network export information */
uid_t uid; /* uid that owns msdosfs files */
gid_t gid; /* gid that owns msdosfs files */
mode_t mask; /* mask to be applied for msdosfs perms */
int flags; /* see below */
};
/*
* Msdosfs mount options:
*/
#define MSDOSFSMNT_SHORTNAME 1 /* Force old DOS short names only */
#define MSDOSFSMNT_LONGNAME 2 /* Force Win'95 long names */
#define MSDOSFSMNT_NOWIN95 4 /* Completely ignore Win95 entries */
#define MSDOSFSMNT_GEMDOSFS 8 /* This is a gemdos-flavour */
MOUNT_NFS
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 */
int acregmin; /* Attr cache file recently modified */
int acregmax; /* ac file not recently modified */
int acdirmin; /* ac for dir recently modified */
int acdirmax; /* ac for dir not recently modified */
};
MOUNT_NTFS
struct ntfs_args {
char *fspec; /* block special device to mount */
struct export_args export_info;
/* network export information */
uid_t uid; /* uid that owns ntfs files */
gid_t gid; /* gid that owns ntfs files */
mode_t mode; /* mask to be applied for ntfs perms */
u_long flag; /* additional flags */
};
/*
* ntfs mount options:
*/
#define NTFS_MFLAG_CASEINS 0x00000001
#define NTFS_MFLAG_ALLNAMES 0x00000002
The unmount() function call disassociates the filesystem from the speci-
fied mount point dir.
The flags argument may specify MNT_FORCE to specify that the filesystem
should be forcibly unmounted even if files are still active. Active spe-
cial devices continue to work, but any further accesses to any other ac-
tive files result in errors even if the filesystem is later remounted.
RETURN VALUESmount() returns the value 0 if the mount was successful; otherwise, -1 is
returned and the variable errno is set to indicate the error.
unmount() returns the value 0 if the unmount was successful; otherwise,
-1 is returned and the variable errno is set to indicate the error.
ERRORSmount() will fail when one of the following occurs:
[EPERM] The caller is not the superuser.
[ENAMETOOLONG] The path name exceeded {MNAMELEN} characters.
[ELOOP] Too many symbolic links were encountered in translating a
pathname.
[ENOENT] A component of dir does not exist.
[ENOTDIR] A component of name is not a directory, or a path prefix
of special is not a directory.
[EINVAL] An argument given was invalid.
[EBUSY] Another process currently holds a reference to dir.
[EFAULT] dir points outside the process's allocated address space.
[EOPNOTSUPP] type is not supported by the kernel.
The following errors can occur for a "ufs" filesystem mount:
[ENODEV] A component of ufs_args fspec does not exist.
[ENOTBLK] fspec is not a block device.
[ENXIO] The major device number of fspec is out of range (this indi-
cates no device driver exists for the associated hardware).
[EBUSY] fspec is already mounted.
[EMFILE] No space remains in the mount table.
[EINVAL] The super block for the filesystem had a bad magic number, an
out of range block size, or an invalid combination of flags.
[ENOMEM] Not enough memory was available to read the cylinder group in-
formation for the filesystem.
[EIO] An I/O error occurred while reading the super block or
cylinder group information.
[EFAULT] fspec points outside the process's allocated address space.
[EROFS] The filesystem was not unmounted cleanly and MNT_FORCE was not
specified.
[EROFS] An attempt was made to mount a 4.2BSD filesystem without the
MNT_RDONLY flag.
The following errors can occur for an NFS filesystem mount:
[ETIMEDOUT] NFS timed out trying to contact the server.
[EFAULT] Some part of the information described by nfs_args points
outside the process's allocated address space.
The following errors can occur for a mfs filesystem mount:
[EMFILE] No space remains in the mount table.
[EINVAL] The super block for the filesystem had a bad magic number or an
out of range block size.
[ENOMEM] Not enough memory was available to read the cylinder group in-
formation for the filesystem.
[EIO] A paging error occurred while reading the super block or
cylinder group information.
[EFAULT] Name points outside the process's allocated address space.
unmount() may fail with one of the following errors:
[EPERM] The caller is not the superuser.
[ENOTDIR] A component of the path is not a directory.
[EINVAL] An argument given was invalid.
[ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} characters,
or an entire path name exceeded {PATH_MAX} characters.
[ELOOP] Too many symbolic links were encountered in translating
the pathname.
[EINVAL] The requested directory is not in the mount table.
[EBUSY] A process is holding a reference to a file located on the
filesystem.
[EIO] An I/O error occurred while writing cached filesystem in-
formation.
[EFAULT] dir points outside the process's allocated address space.
A "ufs" or "mfs" mount can also fail if the maximum number of filesystems
are currently mounted.
SEE ALSOstatfs(2), mfs(8), mount(8), umount(8)HISTORYmount() and unmount() function calls appeared in Version 6 AT&T UNIX.
BUGS
Some of the error codes need translation to more obvious messages.
MirOS BSD #10-current December 11, 1993 4
