nfsd: add support for upcall version 2

Version 2 upcalls will allow the nfsd to include a hash of the kerberos
principal string in the Cld_Create upcall. If a principal is present in
the svc_cred, then the hash will be included in the Cld_Create upcall.
We attempt to use the svc_cred.cr_raw_principal (which is returned by
gssproxy) first, and then fall back to using the svc_cred.cr_principal
(which is returned by both gssproxy and rpc.svcgssd). Upon a subsequent
restart, the hash will be returned in the Cld_Gracestart downcall and
stored in the reclaim_str_hashtbl so it can be used when handling
reclaim opens.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

nfsd: add a "GetVersion" upcall for nfsdcld

Add a "GetVersion" upcall to allow nfsd to determine the maximum upcall
version that the nfsdcld userspace daemon supports. If the daemon
responds with -EOPNOTSUPP, then we know it only supports v1.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

nfsd: un-deprecate nfsdcld

When nfsdcld was released, it was quickly deprecated in favor of the
nfsdcltrack usermodehelper, so as to not require another running daemon.
That prevents NFSv4 clients from reclaiming locks from nfsd's running in
containers, since neither nfsdcltrack nor the legacy client tracking
code work in containers.

This commit un-deprecates the use of nfsdcld, with one twist: we will
populate the reclaim_str_hashtbl on startup.

During client tracking initialization, do an upcall ("GraceStart") to
nfsdcld to get a list of clients from the database. nfsdcld will do
one downcall with a status of -EINPROGRESS for each client record in
the database, which in turn will cause an nfs4_client_reclaim to be
added to the reclaim_str_hashtbl. When complete, nfsdcld will do a
final downcall with a status of 0.

This will save nfsd from having to do an upcall to the daemon during
nfs4_check_open_reclaim() processing.

Even though nfsdcld was quickly deprecated, there is a very small chance
of old nfsdcld daemons running in the wild. These will respond to the
new "GraceStart" upcall with -EOPNOTSUPP, in which case we will log a
message and fall back to the original nfsdcld tracking ops (now called
nfsd4_cld_tracking_ops_v0).

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

License cleanup: add SPDX license identifier to uapi header files with a license

Many user space API headers have licensing information, which is either
incomplete, badly formatted or just a shorthand for referring to the
license under which the file is supposed to be. This makes it hard for
compliance tools to determine the correct license.

Update these files with an SPDX license identifier. The identifier was
chosen based on the license information in the file.

GPL/LGPL licensed headers get the matching GPL/LGPL SPDX license
identifier with the added 'WITH Linux-syscall-note' exception, which is
the officially assigned exception identifier for the kernel syscall
exception:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

This exception makes it possible to include GPL headers into non GPL
code, without confusing license compliance tools.

Headers which have either explicit dual licensing or are just licensed
under a non GPL license are updated with the corresponding SPDX
identifier and the GPLv2 with syscall exception identifier. The format
is:
((GPL-2.0 WITH Linux-syscall-note) OR SPDX-ID-OF-OTHER-LICENSE)

SPDX license identifiers are a legally binding shorthand, which can be
used instead of the full boiler plate text. The update does not remove
existing license information as this has to be done on a case by case
basis and the copyright holders might have to be consulted. This will
happen in a separate step.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

uapi: fix linux/nfsd/cld.h userspace compilation errors

Include <linux/types.h> and consistently use types it provides
to fix the following linux/nfsd/cld.h userspace compilation errors:

/usr/include/linux/nfsd/cld.h:40:2: error: unknown type name 'uint16_t'
uint16_t cn_len; /* length of cm_id */
/usr/include/linux/nfsd/cld.h:46:2: error: unknown type name 'uint8_t'
uint8_t cm_vers; /* upcall version */
/usr/include/linux/nfsd/cld.h:47:2: error: unknown type name 'uint8_t'
uint8_t cm_cmd; /* upcall command */
/usr/include/linux/nfsd/cld.h:48:2: error: unknown type name 'int16_t'
int16_t cm_status; /* return code */
/usr/include/linux/nfsd/cld.h:49:2: error: unknown type name 'uint32_t'
uint32_t cm_xid; /* transaction id */
/usr/include/linux/nfsd/cld.h:51:3: error: unknown type name 'int64_t'
int64_t cm_gracetime; /* grace period start time */

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

UAPI: (Scripted) Disintegrate include/linux/nfsd

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>