Mountpoint expiry
-----------------
-The VFS has a mechansim for automatically expiring unused mounts,
+The VFS has a mechanism for automatically expiring unused mounts,
much as it can expire any unused dentry information from the dcache.
-This is guided by the MNT_SHRINKABLE flag. This only applies to
+This is guided by the MNT_SHRINKABLE flag. This only applies to
mounts that were created by `d_automount()` returning a filesystem to be
mounted. As autofs doesn't return such a filesystem but leaves the
mounting to the automount daemon, it must involve the automount daemon
autofs knows whether a process requesting some operation is the daemon
or not based on its process-group id number (see getpgid(1)).
-When an autofs filesystem it mounted the pgid of the mounting
+When an autofs filesystem is mounted the pgid of the mounting
processes is recorded unless the "pgrp=" option is given, in which
case that number is recorded instead. Any request arriving from a
process in that process group is considered to come from the daemon.
numbers for existing filesystems can be found in
`/proc/self/mountinfo`.
- **AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD**: same as `close(ioctlfd)`.
-- **AUTOFS_DEV_IOCTL_SETPIPEFD_CMD**: if the filesystem is in
+- **AUTOFS_DEV_IOCTL_SETPIPEFD_CMD**: if the filesystem is in
catatonic mode, this can provide the write end of a new pipe
in `arg1` to re-establish communication with a daemon. The
process group of the calling process is used to identify the