NAME
mountctl —
execute a mount control
operation
LIBRARY
library “libc”
SYNOPSIS
#include
<sys/mountctl.h>
int
mountctl(const char *path,
int op, int fd,
void *ctl, int ctllen,
void *buf, int buflen);
DESCRIPTION
Themountctl()
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
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.