nfscl: Clear out a lot of cruft related to B_DIRECT

There is only one place in the unpatched sources where B_DIRECT is
set in the NFS client and this code is never executed. As such, this patch
removes this code that is never executed, since B_DIRECT should never
be set.

During a IETF testing event this week, I saw a crash in ncl_doio_directwrite(),
but this function is only called if B_DIRECT is set.
I cannot explain how ncl_doio_directwrite() got called, but once this patch
was applied to the sources, the crash did not recur. This is not surprising,
since this patch deleted the function.

Reviewed by: kib, markj
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D44980

nfsclient: eliminate ncl_writebp()

Use plain bufwrite() instead. ncl_writebp() evolved to mostly repeat
bufwrite() code with some ommisions, most notably runningbufspace
accounting.

Reviewed by: imp, markj, rmacklem
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D43249

sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

nfscl: Add support for a NFSv4 AppendWrite RPC

For IO_APPEND VOP_WRITE()s, the code first does a
Getattr RPC to acquire the file's size, before it
can do the Write RPC.

Although NFS does not have an append write operation,
an NFSv4 compound can use a Verify operation to check
that the client's notion of the file's size is
correct, followed by the Write operation.

This patch modifies the NFSv4 client to use an Appendwrite
RPC, which does a Verify to check the file's size before
doing the Write. This avoids the need for a Getattr RPC
to preceed this RPC and reduces the RPC count by half for
IO_APPEND writes, so long as the client knows the file's
size.

The nfsd structure was moved from the stack to be malloc()'d,
since the kernel stack limit was being exceeded.

While here, fix the types of a few variables, although
there should not be any semantics change caused by these
type changes.

Remove "struct ucred*" argument from vtruncbuf

vtruncbuf takes a "struct ucred*" argument. AFAICT, it's been unused ever
since that function was first added in r34611. Remove it. Also, remove some
"struct ucred" arguments from fuse and nfs functions that were only used by
vtruncbuf.

Reviewed by: cem
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D20377

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

Fix kernel builds with "options NFS_DEBUG" that
were broken by r276096. Also delete the two
kernel options NFS_GATHERDELAY, NFS_WDELAYHASHSIZ
which are no longer used.

Reported by: bz

Modify the experimental (newnfs) NFS client so that it uses the
same diskless NFS root code as the regular client, which
was moved to sys/nfs by r221032. This fixes the newnfs
client so that it can do an NFSv3 diskless root file system.

MFC after: 2 weeks

Change the experimental NFS client so that it creates nfsiod
threads in the same manner as the regular NFS client after
r214026 was committed. This resolves the lors fixed by r214026
and its predecessors for the regular client.

Reviewed by: jhb
MFC after: 2 weeks

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

MFC: r207082
When the experimental NFS client is handling an NFSv4 server reboot
with delegations enabled, the recovery could fail if the renew
thread is trying to return a delegation, since it will not do the
recovery. This patch fixes the above by having nfscl_recalldeleg()
fail with the I/O operations returning EIO, so that they will be
attempted later. Most of the patch consists of adding an argument
to various functions to indicate the delegation recall case where
this needs to be done.

When the experimental NFS client is handling an NFSv4 server reboot
with delegations enabled, the recovery could fail if the renew
thread is trying to return a delegation, since it will not do the
recovery. This patch fixes the above by having nfscl_recalldeleg()
fail with the I/O operations returning EIO, so that they will be
attempted later. Most of the patch consists of adding an argument
to various functions to indicate the delegation recall case where
this needs to be done.

MFC after: 1 week

MFC: r203119
Patch the experimental NFS client in a manner analogous to
r203072 for the regular NFS client. Also, delete two fields
of struct nfsmount that are not used by the FreeBSD port of
the client.

Patch the experimental NFS client in a manner analogous to
r203072 for the regular NFS client. Also, delete two fields
of struct nfsmount that are not used by the FreeBSD port of
the client.

MFC after: 2 weeks

MFC: r201029
When porting the experimental nfs subsystem to the FreeBSD8 krpc,
I added 3 functions that were already in the experimental client
under different names. This patch deletes the functions in the
experimental client and renames the calls to use the other set.
(This is just removal of duplicated code and does not fix any bug.)

When porting the experimental nfs subsystem to the FreeBSD8 krpc,
I added 3 functions that were already in the experimental client
under different names. This patch deletes the functions in the
experimental client and renames the calls to use the other set.
(This is just removal of duplicated code and does not fix any bug.)

MFC after: 2 weeks

Modify the diskless booting code in sys/fs/nfsclient to be compatible
with what is in sys/nfsclient, so that it will at least build now.

Approved by: kib (mentor)

Add the experimental nfs subtree to the kernel, that includes
support for NFSv4 as well as NFSv2 and 3.
It lives in 3 subdirs under sys/fs:
nfs - functions that are common to the client and server
nfsclient - a mutation of sys/nfsclient that call generic functions
to do RPCs and handle state. As such, it retains the
buffer cache handling characteristics and vnode semantics that
are found in sys/nfsclient, for the most part.
nfsserver - the server. It includes a DRC designed specifically for
NFSv4, that is used instead of the generic DRC in sys/rpc.
The build glue will be checked in later, so at this point, it
consists of 3 new subdirs that should not affect kernel building.

Approved by: kib (mentor)