Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC of 234386, 234400, 234441, 234443, 234482, 234483, 235052, 235241,
235246, and 235619

MFC: 234386

Replace the MNT_VNODE_FOREACH interface with MNT_VNODE_FOREACH_ALL.
The primary changes are that the user of the interface no longer
needs to manage the mount-mutex locking and that the vnode that
is returned has its mutex locked (thus avoiding the need to check
to see if its is DOOMED or other possible end of life senarios).

To minimize compatibility issues for third-party developers, the
old MNT_VNODE_FOREACH interface will remain available so that this
change can be MFC'ed to 9. Following the MFC to 9, MNT_VNODE_FOREACH
will be removed in head.

The reason for this update is to prepare for the addition of the
MNT_VNODE_FOREACH_ACTIVE interface that will loop over just the
active vnodes associated with a mount point (typically less than
1% of the vnodes associated with the mount point).

Reviewed by: kib
Tested by: Peter Holm
MFC after: 2 weeks

MFC: 234400

Drop export of vdestroy() function from kern/vfs_subr.c as it is
used only as a helper function in that file. Replace sole call to
vbusy() with inline code in vholdl(). Replace sole calls to vfree()
and vdestroy() with inline code in vdropl().

The Clang compiler already inlines these functions, so they do not
show up in a kernel backtrace which is confusing. Also you cannot
set their frame in kgdb which means that it is impossible to view
their local variables. So, while the produced code is unchanged,
the debugging should be easier.

Discussed with: kib
MFC after: 2 weeks

MFC: 234441

Fix a memory leak of M_VNODE_MARKER introduced in 234386.

Found by: Peter Holm

MFC: 234443

Delete a no longer useful VNASSERT missed during changes in 234400.

Suggested by: kib

MFC: 234482

This change creates a new list of active vnodes associated with
a mount point. Active vnodes are those with a non-zero use or hold
count, e.g., those vnodes that are not on the free list. Note that
this list is in addition to the list of all the vnodes associated
with a mount point.

To avoid adding another set of linkage pointers to the vnode
structure, the active list uses the existing linkage pointers
used by the free list (previously named v_freelist, now renamed
v_actfreelist).

This update adds the MNT_VNODE_FOREACH_ACTIVE interface that loops
over just the active vnodes associated with a mount point (typically
less than 1% of the vnodes associated with the mount point).

Reviewed by: kib
Tested by: Peter Holm
MFC after: 2 weeks

MFC: 234483

This update uses the MNT_VNODE_FOREACH_ACTIVE interface that loops
over just the active vnodes associated with a mount point to replace
MNT_VNODE_FOREACH_ALL in the vfs_msync, ffs_sync_lazy, and qsync
routines.

The vfs_msync routine is run every 30 seconds for every writably
mounted filesystem. It ensures that any files mmap'ed from the
filesystem with modified pages have those pages queued to be
written back to the file from which they are mapped.

The ffs_lazy_sync and qsync routines are run every 30 seconds for
every writably mounted UFS/FFS filesystem. The ffs_lazy_sync routine
ensures that any files that have been accessed in the previous
30 seconds have had their access times queued for updating in the
filesystem. The qsync routine ensures that any files with modified
quotas have those quotas queued to be written back to their
associated quota file.

In a system configured with 250,000 vnodes, less than 1000 are
typically active at any point in time. Prior to this change all
250,000 vnodes would be locked and inspected twice every minute
by the syncer. For UFS/FFS filesystems they would be locked and
inspected six times every minute (twice by each of these three
routines since each of these routines does its own pass over the
vnodes associated with a mount point). With this change the syncer
now locks and inspects only the tiny set of vnodes that are active.

Reviewed by: kib
Tested by: Peter Holm
MFC after: 2 weeks

MFC: 235052 (by pluknet)

Fix mount mutex handling missed in r234386.

MFC: 235241 (by pluknet)

Fix mount interlock oversights from the previous change in r234386.

Reported by: dougb
Submitted by: Mateusz Guzik <mjguzik at gmail com>
Reviewed by: Kirk McKusick
Tested by: pho

MFC: 235246

Fix mount mutex handling missed in r234386.

MFC: 235619

Update comment to document that the vnode free-list mutex needs to be
held when updating mnt_activevnodelist and mnt_activevnodelistsize.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Simple find/replace of VOP_ISLOCKED -> NFSVOPISLOCKED. This is done so that NFSVOPISLOCKED can be modified later to add enhanced logging and assertions.

Reviewed by: rmacklem
Approved by: zml (mentor)
MFC after: 2 weeks

Simple find/replace of vn_lock -> NFSVOPLOCK. This is done so that NFSVOPLOCK can be modified later to add enhanced logging and assertions.

Reviewed by: rmacklem
Approved by: zml (mentor)
MFC after: 2 weeks

Add DTrace support to the new NFS client. This is essentially
cloned from the old NFS client, plus additions for NFSv4. A
review of this code is in progress, however it was felt by the
reviewer that it could go in now, before code slush. Any changes
required by the review can be committed as bug fixes later.

Change the sysctl naming for the old and new NFS clients
to vfs.oldnfs.xxx and vfs.nfs.xxx respectively. This makes
the default nfs client use vfs.nfs.xxx after r221124.

In ncl_printf(), call vprintf() instead of printf().

MFC after: 3 days

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

Modify the return value for nfscl_mustflush() from boolean_t,
which I mistakenly thought was correct w.r.t. style(9), back
to int and add the checks for != 0. This is just a stylistic
modification.

MFC after: 1 week

Move sys/nfsclient/nfs_lock.c into sys/nfs and build it as a separate
module that can be used by both the regular and experimental nfs
clients. This fixes the problem reported by jh@ where /dev/nfslock
would be registered twice when both nfs clients were used.
I also defined the size of the lm_fh field to be the correct value,
as it should be the maximum size of an NFSv3 file handle.

Reviewed by: jh
MFC after: 2 weeks

Change the nfscl_mustflush() function in the experimental NFSv4
client to return a boolean_t in order to make it more compatible
with style(9).

MFC after: 2 weeks

For the experimental NFSv4 client, do not use cached attributes
that were invalidated, even when a delegation for the file is held.

MFC after: 2 weeks

In NFS clients, instead of inconsistently using #ifdef
DIAGNOSTIC and #ifndef DIAGNOSTIC for debug assertions, prefer
KASSERT(). Also change one #ifdef DIAGNOSTIC in the new nfs server.

Submitted by: Mikolaj Golub <to.my.trociny gmail com>
MFC after: 2 weeks

Allow the experimental NFSv4 client to use cached attributes
when a write delegation is held. Also, add a missing
mtx_unlock() call for the ACL debugging code.

MFC after: 5 days

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

Unloading of the nfscl module is unsupported because newnfslock doesn't
support unloading. It's not trivial to implement newnfslock unloading so
for now just admit that unloading is unsupported and refuse to attempt
unload in all nfscl module event handlers.

Reviewed by: rmacklem
Approved by: trasz (mentor)

Apply the same patch as r196205 for nfs_upgrade_lock() and
nfs_downgrade_lock() to the experimental nfs client.

Approved by: re (kensmith), 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)