unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (OpenBSD-5.7)
Page:
Section:
Apropos / Subsearch:
optional field

MOUNT(2)                    BSD System Calls Manual                   MOUNT(2)

NAME
     mount, unmount -- mount or dismount a filesystem

SYNOPSIS
     #include <&lt;sys/param.h>&gt;
     #include <&lt;sys/mount.h>&gt;

     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 suc-
     cessful mount are swept under the carpet, so to speak, and are unavail-
     able 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 spe-
     cific data are:

     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.*/
           #define ISOFSMNT_SESS     0x00000010 /* use iso_args.sess */

     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 */

     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

     MOUNT_UDF
           struct udf_args {
                   char    *fspec; /* block special device to mount */
           };

     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
     active files result in errors even if the filesystem is later remounted.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     mount() 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.

     [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
                information 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.

     [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
               information 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 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 pathname (including the terminating NUL)
                     exceeded PATH_MAX bytes.

     [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
                     information.

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

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

HISTORY
     The mount() and unmount() system calls first appeared in Version 1 AT&T
     UNIX.  The flags argument is supported by mount() since Version 5 AT&T
     UNIX and by unmount() since 4.3BSD-Reno.  The current calling convention
     involving type and data arguments was introduced by 4.3BSD-Reno as well.

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

BSD                            January 19, 2015                            BSD