• Ian Kent's avatar
    autofs4: add miscellaneous device for ioctls · 8d7b48e0
    Ian Kent authored
    Add a miscellaneous device to the autofs4 module for routing ioctls.  This
    provides the ability to obtain an ioctl file handle for an autofs mount
    point that is possibly covered by another mount.
    The actual problem with autofs is that it can't reconnect to existing
    mounts.  Immediately one things of just adding the ability to remount
    autofs file systems would solve it, but alas, that can't work.  This is
    because autofs direct mounts and the implementation of "on demand mount
    and expire" of nested mount trees have the file system mounted on top of
    the mount trigger dentry.
    To resolve this a miscellaneous device node for routing ioctl commands to
    these mount points has been implemented in the autofs4 kernel module and a
    library added to autofs.  This provides the ability to open a file
    descriptor for these over mounted autofs mount points.
    Please refer to Documentation/filesystems/autofs4-mount-control.txt for a
    discussion of the problem, implementation alternatives considered and a
    description of the interface.
    [akpm@linux-foundation.org: coding-style fixes]
    [akpm@linux-foundation.org: build fix]
    Signed-off-by: default avatarIan Kent <raven@themaw.net>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>