Fix smbfs to not zero out statfs f_flags field. Previously, this
made getmntinfo() return empty flags for smbfs filesystems when
called with MNT_WAIT. It's not visible with mount(8), since it uses
MNT_NOWAIT, but broke autounmount(8) operation.

PR:		195161
Differential Revision:	https://reviews.freebsd.org/D1194
Reviewed by:	kib@
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Partially reconstruct Active/Standby clusting.

In this mode one head is in Active state, supporting all commands, while
another is in Standby state, supporting only minimal LUN discovery subset.

It is still incomplete since Standby state requires reservation support,
which is impossible to do right without having interlink between heads.
But it allows to run some basic experiments.
Log errors for absent LUNs too.

MFC after:	1 week
Fix build for certain MIPS kernels hiding an unused variable under #ifndef.
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/ptrace
Reduce race between LUN destruction and request arrival.

MFC after:	1 week
Remove bunch of unused lun variables.

MFC after:	1 week
Add missing error checking for kernel_port_{add,remove}().  Both can fail
for reasons yet unknown; don't make it increment cumulated_error as a kind
of temporary workaround.

MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Simply remove the tmp dir before creating the symlink. We are doing
chroots all over the place, so there is bound to be a stale file lying
around in there (in my case samba lock files from creating accounts). If
we don't do that, the symlink later will fail.
Close race between cfiscsi_offline() and new connection arrival.

Incoming connection should be either rejected or accepted and terminated.
Document use of wildcards (*) and ampersands (&) in autofs map files.

Differential Revision:	https://reviews.freebsd.org/D1199
Reviewed by:	wblock@
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Fix error handling.

MFC after:	1 month
Coverity CID:	1249768
Sponsored by:	The FreeBSD Foundation
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/ptrace