MOUNT(2)                  OpenBSD 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
                      super-user 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_UNION        Mount in such a way that the contents of the underlying
                      filesystem are not (totally) obscured (see
                      mount_union(8)).

     MNT_SYNCHRONOUS  All I/O to the filesystem should be done synchronously.

     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 spe-
     cific data are:

     MOUNT_FFS
           struct ufs_args {
                 char      *fspec;             /* block special file to mount */
                 struct    export_args export; /* network export information */
           };

     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_MFS
           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 */
           };

     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 VALUES
     mount() 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.

ERRORS
     mount() will fail when one of the following occurs:

     [EPERM]         The caller is not the super-user.

     [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 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]        A pathname contains a character with the high-order bit

                     set.

     [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 or
                an out of range block size.

     [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 cylin-
                der group information.

     [EFAULT]   fspec points outside the process's allocated address space.

     The following errors can occur for a 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 cylin-
               der 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 super-user.

     [ENOTDIR]       A component of the path is not a directory.

     [EINVAL]        The pathname contains a character with the high-order bit
                     set.

     [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 ALSO
     statfs(2),  mfs(8),  mount(8),  umount(8)

BUGS
     Some of the error codes need translation to more obvious messages.

HISTORY
     mount() and unmount() function calls appeared in Version 6 AT&T UNIX.

OpenBSD 2.6                    December 11, 1993                             4