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MOUNTCTL(2)              DragonFly System Calls Manual             MOUNTCTL(2)


NAME

     mountctl -- execute a mount control operation


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <sys/mountctl.h>

     int
     mountctl(const char *path, int op, int fd, void *ctl, int ctllen,
         void *buf, int buflen);


DESCRIPTION

     The mountctl() system call executes the mount control operation op on the
     mount point path.  An optional file descriptor fd can be passed, or set
     to -1 if unneeded.  The ctl argument is for passing operation specific
     data and usually points to some struct (see CONTROL OPERATIONS for
     further information).  The data's size is specified by ctllen.  The buf
     and buflen arguments are used if the operation needs to return data to
     the caller or set to NULL and 0 if unused.


CONTROL OPERATIONS

     The following operations are defined in <sys/mountctl.h>:

     MOUNTCTL_SET_EXPORT
             Set export control of a filesystem.  This operation needs a
             struct export_args passed in ctl.  Note that export control for
             numerous filesystems may still only be settable with mount(2).
             New software should attempt to use mountctl() before using the
             old mount(2) method.

     MOUNTCTL_INSTALL_VFS_JOURNAL
             Install a journal on a mount point.  This operation needs a
             struct mountctl_install_journal passed in ctl.  The journal file
             must be specified via fd.  A mount point may have multiple
             journals attached to it.

     MOUNTCTL_REMOVE_VFS_JOURNAL
             Disassociate a journal from a mount point.  This operation needs
             a struct mountctl_remove_journal passed in ctl.

     MOUNTCTL_RESTART_VFS_JOURNAL
             Restart a journal with a new descriptor.  This operation needs a
             struct mountctl_restart_journal passed in ctl.  The journal file
             must be specified via fd.

     MOUNTCTL_STATUS_VFS_JOURNAL
             Return a journal's status.  This operation needs a struct
             mountctl_status_journal passed in ctl and an array of struct
             mountctl_journal_ret_status in buf.

     MOUNTCTL_MOUNTFLAGS
             It will store a comma separated string buffer in the buf
             parameter with the name list of the currently set user mount
             flags. The buf will be sized at most buflen bytes.


RETURN VALUES

     Upon successful completion, the number of copied bytes is returned;
     otherwise the value -1 is returned and the global variable errno is set
     to indicate the error.


ERRORS

     The mountctl() function will fail when one of the following occurs:

     [EBADF]            Fd is not an active descriptor.

     [EINVAL]           The specified ctllen is not 0-1024, buflen is not
                        0-16384, or path is NULL.

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


SEE ALSO

     mount(2), mountctl(8)


HISTORY

     The mountctl() system call first appeared in DragonFly 1.1.


AUTHORS

     The mountctl() system call was written by Matthew Dillon and this manual
     page was written by Sascha Wildner.

DragonFly 4.3                    July 21, 2009                   DragonFly 4.3

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