/* $NetBSD: nfs_nfsdcache.c,v 1.5 2024/07/05 04:31:52 rin Exp $ */
/*-
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Rick Macklem at The University of Guelph.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* Here is the basic algorithm:
* First, some design criteria I used:
* - I think a false hit is more serious than a false miss
* - A false hit for an RPC that has Op(s) that order via seqid# must be
* avoided at all cost
* - A valid hit will probably happen a long time after the original reply
* and the TCP socket that the original request was received on will no
* longer be active
* (The long time delay implies to me that LRU is not appropriate.)
* - The mechanism will satisfy the requirements of ordering Ops with seqid#s
* in them as well as minimizing the risk of redoing retried non-idempotent
* Ops.
* Because it is biased towards avoiding false hits, multiple entries with
* the same xid are to be expected, especially for the case of the entry
* in the cache being related to a seqid# sequenced Op.
*
* The basic algorithm I'm about to code up:
* - Null RPCs bypass the cache and are just done
* For TCP
* - key on <xid, NFS version> (as noted above, there can be several
* entries with the same key)
* When a request arrives:
* For all that match key
* - if RPC# != OR request_size !=
* - not a match with this one
* - if NFSv4 and received on same TCP socket OR
* received on a TCP connection created before the
* entry was cached
* - not a match with this one
* (V2,3 clients might retry on same TCP socket)
* - calculate checksum on first N bytes of NFS XDR
* - if checksum !=
* - not a match for this one
* If any of the remaining ones that match has a
* seqid_refcnt > 0
* - not a match (go do RPC, using new cache entry)
* If one match left
* - a hit (reply from cache)
* else
* - miss (go do RPC, using new cache entry)
*
* During processing of NFSv4 request:
* - set a flag when a non-idempotent Op is processed
* - when an Op that uses a seqid# (Open,...) is processed
* - if same seqid# as referenced entry in cache
* - free new cache entry
* - reply from referenced cache entry
* else if next seqid# in order
* - free referenced cache entry
* - increment seqid_refcnt on new cache entry
* - set pointer from Openowner/Lockowner to
* new cache entry (aka reference it)
* else if first seqid# in sequence
* - increment seqid_refcnt on new cache entry
* - set pointer from Openowner/Lockowner to
* new cache entry (aka reference it)
*
* At end of RPC processing:
* - if seqid_refcnt > 0 OR flagged non-idempotent on new
* cache entry
* - save reply in cache entry
* - calculate checksum on first N bytes of NFS XDR
* request
* - note op and length of XDR request (in bytes)
* - timestamp it
* else
* - free new cache entry
* - Send reply (noting info for socket activity check, below)
*
* For cache entries saved above:
* - if saved since seqid_refcnt was > 0
* - free when seqid_refcnt decrements to 0
* (when next one in sequence is processed above, or
* when Openowner/Lockowner is discarded)
* else { non-idempotent Op(s) }
* - free when
* - some further activity observed on same
* socket
* (I'm not yet sure how I'm going to do
* this. Maybe look at the TCP connection
* to see if the send_tcp_sequence# is well
* past sent reply OR K additional RPCs
* replied on same socket OR?)
* OR
* - when very old (hours, days, weeks?)
*
* For UDP (v2, 3 only), pretty much the old way:
* - key on <xid, NFS version, RPC#, Client host ip#>
* (at most one entry for each key)
*
* When a Request arrives:
* - if a match with entry via key
* - if RPC marked In_progress
* - discard request (don't send reply)
* else
* - reply from cache
* - timestamp cache entry
* else
* - add entry to cache, marked In_progress
* - do RPC
* - when RPC done
* - if RPC# non-idempotent
* - mark entry Done (not In_progress)
* - save reply
* - timestamp cache entry
* else
* - free cache entry
* - send reply
*
* Later, entries with saved replies are free'd a short time (few minutes)
* after reply sent (timestamp).
* Reference: Chet Juszczak, "Improving the Performance and Correctness
* of an NFS Server", in Proc. Winter 1989 USENIX Conference,
* pages 53-63. San Diego, February 1989.
* for the UDP case.
* nfsrc_floodlevel is set to the allowable upper limit for saved replies
* for TCP. For V3, a reply won't be saved when the flood level is
* hit. For V4, the non-idempotent Op will return NFSERR_RESOURCE in
* that case. This level should be set high enough that this almost
* never happens.
*/
#ifndef APPLEKEXT
#include <fs/nfs/common/nfsport.h>
/*
* Initialize the server request cache list
*/
APPLESTATIC void
nfsrvd_initcache(void)
{
int i;
static int inited = 0;
if (inited)
return;
inited = 1;
for (i = 0; i < NFSRVCACHE_HASHSIZE; i++) {
LIST_INIT(&nfsrvudphashtbl[i]);
LIST_INIT(&nfsrchash_table[i].tbl);
LIST_INIT(&nfsrcahash_table[i].tbl);
}
TAILQ_INIT(&nfsrvudplru);
nfsrc_tcpsavedreplies = 0;
nfsrc_udpcachesize = 0;
nfsstatsv1.srvcache_tcppeak = 0;
nfsstatsv1.srvcache_size = 0;
}
/*
* Get a cache entry for this request. Basically just malloc a new one
* and then call nfsrc_getudp() or nfsrc_gettcp() to do the rest.
*/
APPLESTATIC int
nfsrvd_getcache(struct nfsrv_descript *nd)
{
struct nfsrvcache *newrp;
int ret;
/*
* Update a request cache entry after the rpc has been done
*/
APPLESTATIC struct nfsrvcache *
nfsrvd_updatecache(struct nfsrv_descript *nd)
{
struct nfsrvcache *rp;
struct nfsrvcache *retrp = NULL;
mbuf_t m;
struct mtx *mutex;
rp = nd->nd_rp;
if (!rp)
panic("nfsrvd_updatecache null rp");
nd->nd_rp = NULL;
mutex = nfsrc_cachemutex(rp);
mtx_lock(mutex);
nfsrc_lock(rp);
if (!(rp->rc_flag & RC_INPROG))
panic("nfsrvd_updatecache not inprog");
rp->rc_flag &= ~RC_INPROG;
if (rp->rc_flag & RC_UDP) {
TAILQ_REMOVE(&nfsrvudplru, rp, rc_lru);
TAILQ_INSERT_TAIL(&nfsrvudplru, rp, rc_lru);
}
/*
* Reply from cache is a special case returned by nfsrv_checkseqid().
*/
if (nd->nd_repstat == NFSERR_REPLYFROMCACHE) {
nfsstatsv1.srvcache_nonidemdonehits++;
mtx_unlock(mutex);
nd->nd_repstat = 0;
mbuf_freem(nd->nd_mreq);
if (!(rp->rc_flag & RC_REPMBUF))
panic("reply from cache");
nd->nd_mreq = m_copym(rp->rc_reply, 0,
M_COPYALL, M_WAITOK);
rp->rc_timestamp = NFSD_MONOSEC + nfsrc_tcptimeout;
nfsrc_unlock(rp);
goto out;
}
/*
* If rc_refcnt > 0, save it
* For UDP, save it if ND_SAVEREPLY is set
* For TCP, save it if ND_SAVEREPLY and nfsrc_tcpnonidempotent is set
*/
if (nd->nd_repstat != NFSERR_DONTREPLY &&
(rp->rc_refcnt > 0 ||
((nd->nd_flag & ND_SAVEREPLY) && (rp->rc_flag & RC_UDP)) ||
((nd->nd_flag & ND_SAVEREPLY) && !(rp->rc_flag & RC_UDP) &&
nfsrc_tcpsavedreplies <= nfsrc_floodlevel &&
nfsrc_tcpnonidempotent))) {
if (rp->rc_refcnt > 0) {
if (!(rp->rc_flag & RC_NFSV4))
panic("update_cache refcnt");
rp->rc_flag |= RC_REFCNT;
}
if ((nd->nd_flag & ND_NFSV2) &&
nfsv2_repstat[newnfsv2_procid[nd->nd_procnum]]) {
rp->rc_status = nd->nd_repstat;
rp->rc_flag |= RC_REPSTATUS;
mtx_unlock(mutex);
} else {
if (!(rp->rc_flag & RC_UDP)) {
atomic_add_int(&nfsrc_tcpsavedreplies, 1);
if (nfsrc_tcpsavedreplies >
nfsstatsv1.srvcache_tcppeak)
nfsstatsv1.srvcache_tcppeak =
nfsrc_tcpsavedreplies;
}
mtx_unlock(mutex);
m = m_copym(nd->nd_mreq, 0, M_COPYALL, M_WAITOK);
mtx_lock(mutex);
rp->rc_reply = m;
rp->rc_flag |= RC_REPMBUF;
mtx_unlock(mutex);
}
if (rp->rc_flag & RC_UDP) {
rp->rc_timestamp = NFSD_MONOSEC +
NFSRVCACHE_UDPTIMEOUT;
nfsrc_unlock(rp);
} else {
rp->rc_timestamp = NFSD_MONOSEC + nfsrc_tcptimeout;
if (rp->rc_refcnt > 0)
nfsrc_unlock(rp);
else
retrp = rp;
}
} else {
nfsrc_freecache(rp);
mtx_unlock(mutex);
}
out:
NFSEXITCODE2(0, nd);
return (retrp);
}
/*
* Invalidate and, if possible, free an in prog cache entry.
* Must not sleep.
*/
APPLESTATIC void
nfsrvd_delcache(struct nfsrvcache *rp)
{
struct mtx *mutex;
mutex = nfsrc_cachemutex(rp);
if (!(rp->rc_flag & RC_INPROG))
panic("nfsrvd_delcache not in prog");
mtx_lock(mutex);
rp->rc_flag &= ~RC_INPROG;
if (rp->rc_refcnt == 0 && !(rp->rc_flag & RC_LOCKED))
nfsrc_freecache(rp);
mtx_unlock(mutex);
}
/*
* Called after nfsrvd_updatecache() once the reply is sent, to update
* the entry's sequence number and unlock it. The argument is
* the pointer returned by nfsrvd_updatecache().
*/
APPLESTATIC void
nfsrvd_sentcache(struct nfsrvcache *rp, int have_seq, uint32_t seq)
{
struct nfsrchash_bucket *hbp;
KASSERT(rp->rc_flag & RC_LOCKED, ("nfsrvd_sentcache not locked"));
if (have_seq) {
hbp = NFSRCAHASH(rp->rc_sockref);
mtx_lock(&hbp->mtx);
rp->rc_tcpseq = seq;
if (rp->rc_acked != RC_NO_ACK)
LIST_INSERT_HEAD(&hbp->tbl, rp, rc_ahash);
rp->rc_acked = RC_NO_ACK;
mtx_unlock(&hbp->mtx);
}
nfsrc_unlock(rp);
}
/*
* Get a cache entry for TCP
* - key on <xid, nfs version>
* (allow multiple entries for a given key)
*/
static int
nfsrc_gettcp(struct nfsrv_descript *nd, struct nfsrvcache *newrp)
{
struct nfsrvcache *rp, *nextrp;
int i;
struct nfsrvcache *hitrp;
struct nfsrvhashhead *hp, nfsrc_templist;
int hit, ret = 0;
struct mtx *mutex;
mutex = nfsrc_cachemutex(newrp);
hp = NFSRCHASH(newrp->rc_xid);
newrp->rc_reqlen = nfsrc_getlenandcksum(nd->nd_mrep, &newrp->rc_cksum);
tryagain:
mtx_lock(mutex);
hit = 1;
LIST_INIT(&nfsrc_templist);
/*
* Get all the matches and put them on the temp list.
*/
rp = LIST_FIRST(hp);
while (rp != NULL) {
nextrp = LIST_NEXT(rp, rc_hash);
if (newrp->rc_xid == rp->rc_xid &&
(!(rp->rc_flag & RC_INPROG) ||
((newrp->rc_flag & RC_SAMETCPCONN) &&
newrp->rc_sockref == rp->rc_sockref)) &&
(newrp->rc_flag & rp->rc_flag & RC_NFSVERS) &&
newrp->rc_proc == rp->rc_proc &&
((newrp->rc_flag & RC_NFSV4) &&
newrp->rc_sockref != rp->rc_sockref &&
newrp->rc_cachetime >= rp->rc_cachetime)
&& newrp->rc_reqlen == rp->rc_reqlen &&
newrp->rc_cksum == rp->rc_cksum) {
LIST_REMOVE(rp, rc_hash);
LIST_INSERT_HEAD(&nfsrc_templist, rp, rc_hash);
}
rp = nextrp;
}
/*
* Now, use nfsrc_templist to decide if there is a match.
*/
i = 0;
LIST_FOREACH(rp, &nfsrc_templist, rc_hash) {
i++;
if (rp->rc_refcnt > 0) {
hit = 0;
break;
}
}
/*
* Can be a hit only if one entry left.
* Note possible hit entry and put nfsrc_templist back on hash
* list.
*/
if (i != 1)
hit = 0;
hitrp = rp = LIST_FIRST(&nfsrc_templist);
while (rp != NULL) {
nextrp = LIST_NEXT(rp, rc_hash);
LIST_REMOVE(rp, rc_hash);
LIST_INSERT_HEAD(hp, rp, rc_hash);
rp = nextrp;
}
if (LIST_FIRST(&nfsrc_templist) != NULL)
panic("nfs gettcp cache templist");
if (hit) {
rp = hitrp;
if ((rp->rc_flag & RC_LOCKED) != 0) {
rp->rc_flag |= RC_WANTED;
(void)mtx_sleep(rp, mutex, (PZERO - 1) | PDROP,
"nfsrc", 10 * hz);
goto tryagain;
}
if (rp->rc_flag == 0)
panic("nfs tcp cache0");
rp->rc_flag |= RC_LOCKED;
if (rp->rc_flag & RC_INPROG) {
nfsstatsv1.srvcache_inproghits++;
mtx_unlock(mutex);
if (newrp->rc_sockref == rp->rc_sockref)
nfsrc_marksametcpconn(rp->rc_sockref);
ret = RC_DROPIT;
} else if (rp->rc_flag & RC_REPSTATUS) {
/*
* V2 only.
*/
nfsstatsv1.srvcache_nonidemdonehits++;
mtx_unlock(mutex);
if (newrp->rc_sockref == rp->rc_sockref)
nfsrc_marksametcpconn(rp->rc_sockref);
ret = RC_REPLY;
nfsrvd_rephead(nd);
*(nd->nd_errp) = rp->rc_status;
rp->rc_timestamp = NFSD_MONOSEC + nfsrc_tcptimeout;
} else if (rp->rc_flag & RC_REPMBUF) {
nfsstatsv1.srvcache_nonidemdonehits++;
mtx_unlock(mutex);
if (newrp->rc_sockref == rp->rc_sockref)
nfsrc_marksametcpconn(rp->rc_sockref);
ret = RC_REPLY;
nd->nd_mreq = m_copym(rp->rc_reply, 0,
M_COPYALL, M_WAITOK);
rp->rc_timestamp = NFSD_MONOSEC + nfsrc_tcptimeout;
} else {
panic("nfs tcp cache1");
}
nfsrc_unlock(rp);
free((caddr_t)newrp, M_NFSRVCACHE);
goto out;
}
nfsstatsv1.srvcache_misses++;
atomic_add_int(&nfsstatsv1.srvcache_size, 1);
/*
* For TCP, multiple entries for a key are allowed, so don't
* chain it into the hash table until done.
*/
newrp->rc_cachetime = NFSD_MONOSEC;
newrp->rc_flag |= RC_INPROG;
LIST_INSERT_HEAD(hp, newrp, rc_hash);
mtx_unlock(mutex);
nd->nd_rp = newrp;
ret = RC_DOIT;
/*
* Free up the entry.
* Must not sleep.
*/
static void
nfsrc_freecache(struct nfsrvcache *rp)
{
struct nfsrchash_bucket *hbp;
LIST_REMOVE(rp, rc_hash);
if (rp->rc_flag & RC_UDP) {
TAILQ_REMOVE(&nfsrvudplru, rp, rc_lru);
nfsrc_udpcachesize--;
} else if (rp->rc_acked != RC_NO_SEQ) {
hbp = NFSRCAHASH(rp->rc_sockref);
mtx_lock(&hbp->mtx);
if (rp->rc_acked == RC_NO_ACK)
LIST_REMOVE(rp, rc_ahash);
mtx_unlock(&hbp->mtx);
}
nfsrc_wanted(rp);
if (rp->rc_flag & RC_REPMBUF) {
mbuf_freem(rp->rc_reply);
if (!(rp->rc_flag & RC_UDP))
atomic_add_int(&nfsrc_tcpsavedreplies, -1);
}
FREE((caddr_t)rp, M_NFSRVCACHE);
atomic_add_int(&nfsstatsv1.srvcache_size, -1);
}
/*
* Clean out the cache. Called when nfsserver module is unloaded.
*/
APPLESTATIC void
nfsrvd_cleancache(void)
{
struct nfsrvcache *rp, *nextrp;
int i;
for (i = 0; i < NFSRVCACHE_HASHSIZE; i++) {
mtx_lock(&nfsrchash_table[i].mtx);
LIST_FOREACH_SAFE(rp, &nfsrchash_table[i].tbl, rc_hash, nextrp)
nfsrc_freecache(rp);
mtx_unlock(&nfsrchash_table[i].mtx);
}
mtx_lock(&nfsrc_udpmtx);
for (i = 0; i < NFSRVCACHE_HASHSIZE; i++) {
LIST_FOREACH_SAFE(rp, &nfsrvudphashtbl[i], rc_hash, nextrp) {
nfsrc_freecache(rp);
}
}
nfsstatsv1.srvcache_size = 0;
mtx_unlock(&nfsrc_udpmtx);
nfsrc_tcpsavedreplies = 0;
}
#define HISTSIZE 16
/*
* The basic rule is to get rid of entries that are expired.
*/
void
nfsrc_trimcache(u_int64_t sockref, uint32_t snd_una, int final)
{
struct nfsrchash_bucket *hbp;
struct nfsrvcache *rp, *nextrp;
int force, lastslot, i, j, k, tto, time_histo[HISTSIZE];
time_t thisstamp;
static time_t udp_lasttrim = 0, tcp_lasttrim = 0;
static int onethread = 0, oneslot = 0;
if (atomic_cmpset_acq_int(&onethread, 0, 1) == 0)
return;
if (NFSD_MONOSEC != udp_lasttrim ||
nfsrc_udpcachesize >= (nfsrc_udphighwater +
nfsrc_udphighwater / 2)) {
mtx_lock(&nfsrc_udpmtx);
udp_lasttrim = NFSD_MONOSEC;
TAILQ_FOREACH_SAFE(rp, &nfsrvudplru, rc_lru, nextrp) {
if (!(rp->rc_flag & (RC_INPROG|RC_LOCKED|RC_WANTED))
&& rp->rc_refcnt == 0
&& ((rp->rc_flag & RC_REFCNT) ||
udp_lasttrim > rp->rc_timestamp ||
nfsrc_udpcachesize > nfsrc_udphighwater))
nfsrc_freecache(rp);
}
mtx_unlock(&nfsrc_udpmtx);
}
if (NFSD_MONOSEC != tcp_lasttrim ||
nfsrc_tcpsavedreplies >= nfsrc_tcphighwater) {
force = nfsrc_tcphighwater / 4;
if (force > 0 &&
nfsrc_tcpsavedreplies + force >= nfsrc_tcphighwater) {
for (i = 0; i < HISTSIZE; i++)
time_histo[i] = 0;
i = 0;
lastslot = NFSRVCACHE_HASHSIZE - 1;
} else {
force = 0;
if (NFSD_MONOSEC != tcp_lasttrim) {
i = 0;
lastslot = NFSRVCACHE_HASHSIZE - 1;
} else {
lastslot = i = oneslot;
if (++oneslot >= NFSRVCACHE_HASHSIZE)
oneslot = 0;
}
}
tto = nfsrc_tcptimeout;
tcp_lasttrim = NFSD_MONOSEC;
for (; i <= lastslot; i++) {
mtx_lock(&nfsrchash_table[i].mtx);
LIST_FOREACH_SAFE(rp, &nfsrchash_table[i].tbl, rc_hash,
nextrp) {
if (!(rp->rc_flag &
(RC_INPROG|RC_LOCKED|RC_WANTED))
&& rp->rc_refcnt == 0) {
if ((rp->rc_flag & RC_REFCNT) ||
tcp_lasttrim > rp->rc_timestamp ||
rp->rc_acked == RC_ACK) {
nfsrc_freecache(rp);
continue;
}
if (force == 0)
continue;
/*
* The timestamps range from roughly the
* present (tcp_lasttrim) to the present
* + nfsrc_tcptimeout. Generate a simple
* histogram of where the timeouts fall.
*/
j = rp->rc_timestamp - tcp_lasttrim;
if (j >= tto)
j = HISTSIZE - 1;
else if (j < 0)
j = 0;
else
j = j * HISTSIZE / tto;
time_histo[j]++;
}
}
mtx_unlock(&nfsrchash_table[i].mtx);
}
if (force) {
/*
* Trim some more with a smaller timeout of as little
* as 20% of nfsrc_tcptimeout to try and get below
* 80% of the nfsrc_tcphighwater.
*/
k = 0;
for (i = 0; i < (HISTSIZE - 2); i++) {
k += time_histo[i];
if (k > force)
break;
}
k = tto * (i + 1) / HISTSIZE;
if (k < 1)
k = 1;
thisstamp = tcp_lasttrim + k;
for (i = 0; i < NFSRVCACHE_HASHSIZE; i++) {
mtx_lock(&nfsrchash_table[i].mtx);
LIST_FOREACH_SAFE(rp, &nfsrchash_table[i].tbl,
rc_hash, nextrp) {
if (!(rp->rc_flag &
(RC_INPROG|RC_LOCKED|RC_WANTED))
&& rp->rc_refcnt == 0
&& ((rp->rc_flag & RC_REFCNT) ||
thisstamp > rp->rc_timestamp ||
rp->rc_acked == RC_ACK))
nfsrc_freecache(rp);
}
mtx_unlock(&nfsrchash_table[i].mtx);
}
}
}
atomic_store_rel_int(&onethread, 0);
}
/*
* Add a seqid# reference to the cache entry.
*/
APPLESTATIC void
nfsrvd_refcache(struct nfsrvcache *rp)
{
struct mtx *mutex;
if (rp == NULL)
/* For NFSv4.1, there is no cache entry. */
return;
mutex = nfsrc_cachemutex(rp);
mtx_lock(mutex);
if (rp->rc_refcnt < 0)
panic("nfs cache refcnt");
rp->rc_refcnt++;
mtx_unlock(mutex);
}
/*
* Calculate the length of the mbuf list and a checksum on the first up to
* NFSRVCACHE_CHECKLEN bytes.
*/
static int
nfsrc_getlenandcksum(mbuf_t m1, u_int16_t *cksum)
{
int len = 0, cklen;
mbuf_t m;
m = m1;
while (m) {
len += mbuf_len(m);
m = mbuf_next(m);
}
cklen = (len > NFSRVCACHE_CHECKLEN) ? NFSRVCACHE_CHECKLEN : len;
*cksum = in_cksum(m1, cklen);
return (len);
}
/*
* Mark a TCP connection that is seeing retries. Should never happen for
* NFSv4.
*/
static void
nfsrc_marksametcpconn(u_int64_t sockref)
{
}
