/*      $NetBSD: nfs_srvcache.c,v 1.45 2009/03/15 17:20:10 cegger 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.
 * 3. 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.
 *
 *      @(#)nfs_srvcache.c      8.3 (Berkeley) 3/30/95
 */

/*
 * 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nfs_srvcache.c,v 1.45 2009/03/15 17:20:10 cegger Exp $");

#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/condvar.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/pool.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/socket.h>
#include <sys/socketvar.h>

#include <netinet/in.h>
#include <nfs/nfsm_subs.h>
#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfs.h>
#include <nfs/nfsrvcache.h>
#include <nfs/nfs_var.h>

extern struct nfsstats nfsstats;
extern const int nfsv2_procid[NFS_NPROCS];
long numnfsrvcache, desirednfsrvcache = NFSRVCACHESIZ;
struct pool nfs_reqcache_pool;

#define NFSRCHASH(xid) \
        (&nfsrvhashtbl[((xid) + ((xid) >> 24)) & nfsrvhash])
LIST_HEAD(nfsrvhash, nfsrvcache) *nfsrvhashtbl;
TAILQ_HEAD(nfsrvlru, nfsrvcache) nfsrvlruhead;
kmutex_t nfsrv_reqcache_lock;
u_long nfsrvhash;

#if defined(MBUFTRACE)
static struct mowner nfsd_cache_mowner = MOWNER_INIT("nfsd", "cache");
#endif /* defined(MBUFTRACE) */

#define NETFAMILY(rp) \
                (((rp)->rc_flags & RC_INETADDR) ? AF_INET : -1)

static struct nfsrvcache *nfsrv_lookupcache(struct nfsrv_descript *nd);
static void nfsrv_unlockcache(struct nfsrvcache *rp);

/*
 * Static array that defines which nfs rpc's are nonidempotent
 */
const int nonidempotent[NFS_NPROCS] = {
        false,  /* NULL */
        false,  /* GETATTR */
        true,   /* SETATTR */
        false,  /* LOOKUP */
        false,  /* ACCESS */
        false,  /* READLINK */
        false,  /* READ */
        true,   /* WRITE */
        true,   /* CREATE */
        true,   /* MKDIR */
        true,   /* SYMLINK */
        true,   /* MKNOD */
        true,   /* REMOVE */
        true,   /* RMDIR */
        true,   /* RENAME */
        true,   /* LINK */
        false,  /* READDIR */
        false,  /* READDIRPLUS */
        false,  /* FSSTAT */
        false,  /* FSINFO */
        false,  /* PATHCONF */
        false,  /* COMMIT */
        false,  /* NOOP */
};

/* True iff the rpc reply is an nfs status ONLY! */
static const int nfsv2_repstat[NFS_NPROCS] = {
        false,  /* NULL */
        false,  /* GETATTR */
        false,  /* SETATTR */
        false,  /* NOOP */
        false,  /* LOOKUP */
        false,  /* READLINK */
        false,  /* READ */
        false,  /* Obsolete WRITECACHE */
        false,  /* WRITE */
        false,  /* CREATE */
        true,   /* REMOVE */
        true,   /* RENAME */
        true,   /* LINK */
        true,   /* SYMLINK */
        false,  /* MKDIR */
        true,   /* RMDIR */
        false,  /* READDIR */
        false,  /* STATFS */
};

static void
cleanentry(struct nfsrvcache *rp)
{

        if ((rp->rc_flags & RC_REPMBUF) != 0) {
                m_freem(rp->rc_reply);
        }
        if ((rp->rc_flags & RC_NAM) != 0) {
                m_free(rp->rc_nam);
        }
        rp->rc_flags &= ~(RC_REPSTATUS|RC_REPMBUF);
}

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

        mutex_init(&nfsrv_reqcache_lock, MUTEX_DEFAULT, IPL_NONE);
        nfsrvhashtbl = hashinit(desirednfsrvcache, HASH_LIST, true,
            &nfsrvhash);
        TAILQ_INIT(&nfsrvlruhead);
        pool_init(&nfs_reqcache_pool, sizeof(struct nfsrvcache), 0, 0, 0,
            "nfsreqcachepl", &pool_allocator_nointr, IPL_NONE);
        MOWNER_ATTACH(&nfsd_cache_mowner);
}

void
nfsrv_finicache(void)
{

        nfsrv_cleancache();
        KASSERT(TAILQ_EMPTY(&nfsrvlruhead));
        pool_destroy(&nfs_reqcache_pool);
        hashdone(nfsrvhashtbl, HASH_LIST, nfsrvhash);
        MOWNER_DETACH(&nfsd_cache_mowner);
        mutex_destroy(&nfsrv_reqcache_lock);
}

/*
 * Lookup a cache and lock it
 */
static struct nfsrvcache *
nfsrv_lookupcache(struct nfsrv_descript *nd)
{
        struct nfsrvcache *rp;

        KASSERT(mutex_owned(&nfsrv_reqcache_lock));

loop:
        LIST_FOREACH(rp, NFSRCHASH(nd->nd_retxid), rc_hash) {
                if (nd->nd_retxid == rp->rc_xid &&
                    nd->nd_procnum == rp->rc_proc &&
                    netaddr_match(NETFAMILY(rp), &rp->rc_haddr, nd->nd_nam)) {
                        if ((rp->rc_gflags & RC_G_LOCKED) != 0) {
                                cv_wait(&rp->rc_cv, &nfsrv_reqcache_lock);
                                goto loop;
                        }
                        rp->rc_gflags |= RC_G_LOCKED;
                        break;
                }
        }

        return rp;
}

/*
 * Unlock a cache
 */
static void
nfsrv_unlockcache(struct nfsrvcache *rp)
{

        KASSERT(mutex_owned(&nfsrv_reqcache_lock));

        KASSERT((rp->rc_gflags & RC_G_LOCKED) != 0);
        rp->rc_gflags &= ~RC_G_LOCKED;
        cv_broadcast(&rp->rc_cv);
}

/*
 * 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
 */
int
nfsrv_getcache(struct nfsrv_descript *nd, struct nfssvc_sock *slp, struct mbuf **repp)
{
        struct nfsrvcache *rp, *rpdup;
        struct mbuf *mb;
        struct sockaddr_in *saddr;
        char *bpos;
        int ret;

        mutex_enter(&nfsrv_reqcache_lock);
        rp = nfsrv_lookupcache(nd);
        if (rp) {
                mutex_exit(&nfsrv_reqcache_lock);
found:
                /* If not at end of LRU chain, move it there */
                if (TAILQ_NEXT(rp, rc_lru)) { /* racy but ok */
                        mutex_enter(&nfsrv_reqcache_lock);
                        TAILQ_REMOVE(&nfsrvlruhead, rp, rc_lru);
                        TAILQ_INSERT_TAIL(&nfsrvlruhead, rp, rc_lru);
                        mutex_exit(&nfsrv_reqcache_lock);
                }
                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_flags & RC_REPSTATUS) {
                        nfsstats.srvcache_nonidemdonehits++;
                        nfs_rephead(0, nd, slp, rp->rc_status,
                           0, (u_quad_t *)0, repp, &mb, &bpos);
                        ret = RC_REPLY;
                } else if (rp->rc_flags & 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;
                }
                mutex_enter(&nfsrv_reqcache_lock);
                nfsrv_unlockcache(rp);
                mutex_exit(&nfsrv_reqcache_lock);
                return ret;
        }
        nfsstats.srvcache_misses++;
        if (numnfsrvcache < desirednfsrvcache) {
                numnfsrvcache++;
                mutex_exit(&nfsrv_reqcache_lock);
                rp = pool_get(&nfs_reqcache_pool, PR_WAITOK);
                memset(rp, 0, sizeof *rp);
                cv_init(&rp->rc_cv, "nfsdrc");
                rp->rc_gflags = RC_G_LOCKED;
        } else {
                rp = TAILQ_FIRST(&nfsrvlruhead);
                while ((rp->rc_gflags & RC_G_LOCKED) != 0) {
                        cv_wait(&rp->rc_cv, &nfsrv_reqcache_lock);
                        rp = TAILQ_FIRST(&nfsrvlruhead);
                }
                rp->rc_gflags |= RC_G_LOCKED;
                LIST_REMOVE(rp, rc_hash);
                TAILQ_REMOVE(&nfsrvlruhead, rp, rc_lru);
                mutex_exit(&nfsrv_reqcache_lock);
                cleanentry(rp);
                rp->rc_flags = 0;
        }
        rp->rc_state = RC_INPROG;
        rp->rc_xid = nd->nd_retxid;
        saddr = mtod(nd->nd_nam, struct sockaddr_in *);
        switch (saddr->sin_family) {
        case AF_INET:
                rp->rc_flags |= RC_INETADDR;
                rp->rc_inetaddr = saddr->sin_addr.s_addr;
                break;
        default:
                rp->rc_flags |= RC_NAM;
                rp->rc_nam = m_copym(nd->nd_nam, 0, M_COPYALL, M_WAIT);
                m_claimm(rp->rc_nam, &nfsd_cache_mowner);
                break;
        };
        rp->rc_proc = nd->nd_procnum;
        mutex_enter(&nfsrv_reqcache_lock);
        rpdup = nfsrv_lookupcache(nd);
        if (rpdup != NULL) {
                /*
                 * other thread made duplicate cache entry.
                 */
                KASSERT(numnfsrvcache > 0);
                numnfsrvcache--;
                mutex_exit(&nfsrv_reqcache_lock);
                cleanentry(rp);
                cv_destroy(&rp->rc_cv);
                pool_put(&nfs_reqcache_pool, rp);
                rp = rpdup;
                goto found;
        }
        TAILQ_INSERT_TAIL(&nfsrvlruhead, rp, rc_lru);
        LIST_INSERT_HEAD(NFSRCHASH(nd->nd_retxid), rp, rc_hash);
        nfsrv_unlockcache(rp);
        mutex_exit(&nfsrv_reqcache_lock);
        return RC_DOIT;
}

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

        mutex_enter(&nfsrv_reqcache_lock);
        rp = nfsrv_lookupcache(nd);
        mutex_exit(&nfsrv_reqcache_lock);
        if (rp) {
                cleanentry(rp);
                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 ((nd->nd_flag & ND_NFSV3) == 0 &&
                          nfsv2_repstat[nfsv2_procid[nd->nd_procnum]]) {
                                rp->rc_status = nd->nd_repstat;
                                rp->rc_flags |= RC_REPSTATUS;
                        } else {
                                rp->rc_reply = m_copym(repmbuf,
                                        0, M_COPYALL, M_WAIT);
                                m_claimm(rp->rc_reply, &nfsd_cache_mowner);
                                rp->rc_flags |= RC_REPMBUF;
                        }
                }
                mutex_enter(&nfsrv_reqcache_lock);
                nfsrv_unlockcache(rp);
                mutex_exit(&nfsrv_reqcache_lock);
        }
}

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

        mutex_enter(&nfsrv_reqcache_lock);
        while ((rp = TAILQ_FIRST(&nfsrvlruhead)) != NULL) {
                KASSERT((rp->rc_gflags & RC_G_LOCKED) == 0);
                LIST_REMOVE(rp, rc_hash);
                TAILQ_REMOVE(&nfsrvlruhead, rp, rc_lru);
                KASSERT(numnfsrvcache > 0);
                numnfsrvcache--;
                mutex_exit(&nfsrv_reqcache_lock);
                cleanentry(rp);
                cv_destroy(&rp->rc_cv);
                pool_put(&nfs_reqcache_pool, rp);
                mutex_enter(&nfsrv_reqcache_lock);
        }
        KASSERT(numnfsrvcache == 0);
        mutex_exit(&nfsrv_reqcache_lock);
}