This format seems to have been taken from device mapper header, but
autofs has no such file:function in both kernel and userspace.

Link: http://lkml.kernel.org/r/148577164094.9801.4775075118014742496.stgit@pluto.themaw.netSigned-off-by: NTomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since linux/auto_dev-ioctl.h wasn't included in include/linux/Kbuild
it wasn't moved to uapi/linux as part of the uapi series.

Link: http://lkml.kernel.org/r/20160812024901.12352.10984.stgit@pluto.themaw.netSigned-off-by: NIan Kent <raven@themaw.net>
Cc: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This macro was never used by neither kernel nor userspace, and also
doesn't represent "devid length" in bytes.  (unless it was added to mean
something else).

Link: http://lkml.kernel.org/r/20160812024820.12352.21210.stgit@pluto.themaw.netSigned-off-by: NTomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: NIan Kent <ikent@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since including linux/string.h will now do the right thing remove the
conditional check.
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Try and make the coding style completely consistent throughtout the
autofs module and inline with kernel coding style recommendations.
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

autofs_dev-ioctl.h is included by both the kernel module and user space tools
and it includes two kernel header files.  Compiles work if the kernel headers
are installed but fail otherwise.
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The parameter usage in the device node ioctl code uses arg1 and arg2 as
parameter names.  This patch redefines the parameter names to reflect what
they actually are in an effort to make the code more readable.
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>