usr/src/sys/nfs/nfs_srvcache.c

/*
 * 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.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)nfs_srvcache.c      8.1 (Berkeley) %G%
 */

/*
 * 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.
 */
#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>

#include <netinet/in.h>
#ifdef ISO
#include <netiso/iso.h>
#endif
#include <nfs/nfsm_subs.h>
#include <nfs/rpcv2.h>
#include <nfs/nfsv2.h>
#include <nfs/nfs.h>
#include <nfs/nfsrvcache.h>
#include <nfs/nqnfs.h>

long numnfsrvcache, desirednfsrvcache = NFSRVCACHESIZ;

#define NFSRCHASH(xid)          (((xid) + ((xid) >> 24)) & rheadhash)
static struct nfsrvcache *nfsrvlruhead, **nfsrvlrutail = &nfsrvlruhead;
static struct nfsrvcache **rheadhtbl;
static u_long rheadhash;

#define TRUE    1
#define FALSE   0

#define NETFAMILY(rp) \
                (((rp)->rc_flag & RC_INETADDR) ? AF_INET : AF_ISO)

/*
 * Static array that defines which nfs rpc's are nonidempotent
 */
int nonidempotent[NFS_NPROCS] = {
        FALSE,
        FALSE,
        TRUE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        TRUE,
        TRUE,
        TRUE,
        TRUE,
        TRUE,
        TRUE,
        TRUE,
        TRUE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
};

/* True iff the rpc reply is an nfs status ONLY! */
static int repliesstatus[NFS_NPROCS] = {
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        TRUE,
        TRUE,
        TRUE,
        TRUE,
        FALSE,
        TRUE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        FALSE,
        TRUE,
};

/*
 * Initialize the server request cache list
 */
nfsrv_initcache()
{

        rheadhtbl = hashinit(desirednfsrvcache, M_NFSD, &rheadhash);
}

/*
 * Look for the request in the cache
 * If found then
 *    return action and optionally reply
 * else
 *    insert it in the cache
 *
 * The rules are as follows:
 * - if in progress, return DROP request
 * - if completed within DELAY of the current time, return DROP it
 * - if completed a longer time ago return REPLY if the reply was cached or
 *   return DOIT
 * Update/add new request at end of lru list
 */
nfsrv_getcache(nam, nd, repp)
        struct mbuf *nam;
        register struct nfsd *nd;
        struct mbuf **repp;
{
        register struct nfsrvcache *rp, *rq, **rpp;
        struct mbuf *mb;
        struct sockaddr_in *saddr;
        caddr_t bpos;
        int ret;

        if (nd->nd_nqlflag != NQL_NOVAL)
                return (RC_DOIT);
        rpp = &rheadhtbl[NFSRCHASH(nd->nd_retxid)];
loop:
        for (rp = *rpp; rp; rp = rp->rc_forw) {
            if (nd->nd_retxid == rp->rc_xid && nd->nd_procnum == rp->rc_proc &&
                netaddr_match(NETFAMILY(rp), &rp->rc_haddr, nam)) {
                        if ((rp->rc_flag & RC_LOCKED) != 0) {
                                rp->rc_flag |= RC_WANTED;
                                (void) tsleep((caddr_t)rp, PZERO-1, "nfsrc", 0);
                                goto loop;
                        }
                        rp->rc_flag |= RC_LOCKED;
                        /* If not at end of LRU chain, move it there */
                        if (rp->rc_next) {
                                /* remove from LRU chain */
                                *rp->rc_prev = rp->rc_next;
                                rp->rc_next->rc_prev = rp->rc_prev;
                                /* and replace at end of it */
                                rp->rc_next = NULL;
                                rp->rc_prev = nfsrvlrutail;
                                *nfsrvlrutail = rp;
                                nfsrvlrutail = &rp->rc_next;
                        }
                        if (rp->rc_state == RC_UNUSED)
                                panic("nfsrv cache");
                        if (rp->rc_state == RC_INPROG) {
                                nfsstats.srvcache_inproghits++;
                                ret = RC_DROPIT;
                        } else if (rp->rc_flag & RC_REPSTATUS) {
                                nfsstats.srvcache_nonidemdonehits++;
                                nfs_rephead(0, nd, rp->rc_status,
                                   0, (u_quad_t *)0, repp, &mb, &bpos);
                                ret = RC_REPLY;
                        } else if (rp->rc_flag & RC_REPMBUF) {
                                nfsstats.srvcache_nonidemdonehits++;
                                *repp = m_copym(rp->rc_reply, 0, M_COPYALL,
                                                M_WAIT);
                                ret = RC_REPLY;
                        } else {
                                nfsstats.srvcache_idemdonehits++;
                                rp->rc_state = RC_INPROG;
                                ret = RC_DOIT;
                        }
                        rp->rc_flag &= ~RC_LOCKED;
                        if (rp->rc_flag & RC_WANTED) {
                                rp->rc_flag &= ~RC_WANTED;
                                wakeup((caddr_t)rp);
                        }
                        return (ret);
                }
        }
        nfsstats.srvcache_misses++;
        if (numnfsrvcache < desirednfsrvcache) {
                rp = (struct nfsrvcache *)malloc((u_long)sizeof *rp,
                    M_NFSD, M_WAITOK);
                bzero((char *)rp, sizeof *rp);
                numnfsrvcache++;
                rp->rc_flag = RC_LOCKED;
        } else {
                rp = nfsrvlruhead;
                while ((rp->rc_flag & RC_LOCKED) != 0) {
                        rp->rc_flag |= RC_WANTED;
                        (void) tsleep((caddr_t)rp, PZERO-1, "nfsrc", 0);
                        rp = nfsrvlruhead;
                }
                rp->rc_flag |= RC_LOCKED;
                /* remove from hash chain */
                if (rq = rp->rc_forw)
                        rq->rc_back = rp->rc_back;
                *rp->rc_back = rq;
                /* remove from LRU chain */
                *rp->rc_prev = rp->rc_next;
                rp->rc_next->rc_prev = rp->rc_prev;
                if (rp->rc_flag & RC_REPMBUF)
                        m_freem(rp->rc_reply);
                if (rp->rc_flag & RC_NAM)
                        MFREE(rp->rc_nam, mb);
                rp->rc_flag &= (RC_LOCKED | RC_WANTED);
        }
        /* place at end of LRU list */
        rp->rc_next = NULL;
        rp->rc_prev = nfsrvlrutail;
        *nfsrvlrutail = rp;
        nfsrvlrutail = &rp->rc_next;
        rp->rc_state = RC_INPROG;
        rp->rc_xid = nd->nd_retxid;
        saddr = mtod(nam, struct sockaddr_in *);
        switch (saddr->sin_family) {
        case AF_INET:
                rp->rc_flag |= RC_INETADDR;
                rp->rc_inetaddr = saddr->sin_addr.s_addr;
                break;
        case AF_ISO:
        default:
                rp->rc_flag |= RC_NAM;
                rp->rc_nam = m_copym(nam, 0, M_COPYALL, M_WAIT);
                break;
        };
        rp->rc_proc = nd->nd_procnum;
        /* insert into hash chain */
        if (rq = *rpp)
                rq->rc_back = &rp->rc_forw;
        rp->rc_forw = rq;
        rp->rc_back = rpp;
        *rpp = rp;
        rp->rc_flag &= ~RC_LOCKED;
        if (rp->rc_flag & RC_WANTED) {
                rp->rc_flag &= ~RC_WANTED;
                wakeup((caddr_t)rp);
        }
        return (RC_DOIT);
}

/*
 * Update a request cache entry after the rpc has been done
 */
void
nfsrv_updatecache(nam, nd, repvalid, repmbuf)
        struct mbuf *nam;
        register struct nfsd *nd;
        int repvalid;
        struct mbuf *repmbuf;
{
        register struct nfsrvcache *rp;

        if (nd->nd_nqlflag != NQL_NOVAL)
                return;
loop:
        for (rp = rheadhtbl[NFSRCHASH(nd->nd_retxid)]; rp; rp = rp->rc_forw) {
            if (nd->nd_retxid == rp->rc_xid && nd->nd_procnum == rp->rc_proc &&
                netaddr_match(NETFAMILY(rp), &rp->rc_haddr, nam)) {
                        if ((rp->rc_flag & RC_LOCKED) != 0) {
                                rp->rc_flag |= RC_WANTED;
                                (void) tsleep((caddr_t)rp, PZERO-1, "nfsrc", 0);
                                goto loop;
                        }
                        rp->rc_flag |= RC_LOCKED;
                        rp->rc_state = RC_DONE;
                        /*
                         * If we have a valid reply update status and save
                         * the reply for non-idempotent rpc's.
                         */
                        if (repvalid && nonidempotent[nd->nd_procnum]) {
                                if (repliesstatus[nd->nd_procnum]) {
                                        rp->rc_status = nd->nd_repstat;
                                        rp->rc_flag |= RC_REPSTATUS;
                                } else {
                                        rp->rc_reply = m_copym(repmbuf,
                                                0, M_COPYALL, M_WAIT);
                                        rp->rc_flag |= RC_REPMBUF;
                                }
                        }
                        rp->rc_flag &= ~RC_LOCKED;
                        if (rp->rc_flag & RC_WANTED) {
                                rp->rc_flag &= ~RC_WANTED;
                                wakeup((caddr_t)rp);
                        }
                        return;
                }
        }
}

/*
 * Clean out the cache. Called when the last nfsd terminates.
 */
void
nfsrv_cleancache()
{
        register struct nfsrvcache *rp, *nextrp;

        for (rp = nfsrvlruhead; rp; rp = nextrp) {
                nextrp = rp->rc_next;
                free(rp, M_NFSD);
        }
        bzero((char *)rheadhtbl, (rheadhash + 1) * sizeof(void *));
        nfsrvlruhead = NULL;
        nfsrvlrutail = &nfsrvlruhead;
        numnfsrvcache = 0;
}