/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <nfs/nfs.h>
#include <nfs/nfs4.h>
#include <nfs/rnode4.h>
#include <nfs/nfs4_clnt.h>
#include <sys/bitmap.h>

/*
 * Access cache
 */
static acache4_hash_t *acache4;
static long nacache;    /* used strictly to size the number of hash queues */

static int acache4size;
static int acache4mask;
static struct kmem_cache *acache4_cache;
static int acache4_hashlen = 4;

/*
 * This probably needs to be larger than or equal to
 * log2(sizeof (struct rnode)) due to the way that rnodes are
 * allocated.
 */
#define ACACHE4_SHIFT_BITS      9

static int
acache4hash(rnode4_t *rp, cred_t *cred)
{
        return ((((intptr_t)rp >> ACACHE4_SHIFT_BITS) + crgetuid(cred)) &
            acache4mask);
}

#ifdef DEBUG
static long nfs4_access_cache_hits = 0;
static long nfs4_access_cache_misses = 0;
#endif

nfs4_access_type_t
nfs4_access_check(rnode4_t *rp, uint32_t acc, cred_t *cr)
{
        acache4_t *ap;
        acache4_hash_t *hp;
        nfs4_access_type_t all;
        vnode_t *vp;

        vp = RTOV4(rp);
        if (!ATTRCACHE4_VALID(vp) || nfs4_waitfor_purge_complete(vp))
                return (NFS4_ACCESS_UNKNOWN);

        if (rp->r_acache != NULL) {
                hp = &acache4[acache4hash(rp, cr)];
                rw_enter(&hp->lock, RW_READER);
                ap = hp->next;
                while (ap != (acache4_t *)hp) {
                        if (crcmp(ap->cred, cr) == 0 && ap->rnode == rp) {
                                if ((ap->known & acc) == acc) {
#ifdef DEBUG
                                        nfs4_access_cache_hits++;
#endif
                                        if ((ap->allowed & acc) == acc)
                                                all = NFS4_ACCESS_ALLOWED;
                                        else
                                                all = NFS4_ACCESS_DENIED;
                                } else {
#ifdef DEBUG
                                        nfs4_access_cache_misses++;
#endif
                                        all = NFS4_ACCESS_UNKNOWN;
                                }
                                rw_exit(&hp->lock);
                                return (all);
                        }
                        ap = ap->next;
                }
                rw_exit(&hp->lock);
        }

#ifdef DEBUG
        nfs4_access_cache_misses++;
#endif
        return (NFS4_ACCESS_UNKNOWN);
}

void
nfs4_access_cache(rnode4_t *rp, uint32_t acc, uint32_t resacc, cred_t *cr)
{
        acache4_t *ap;
        acache4_t *nap;
        acache4_hash_t *hp;

        hp = &acache4[acache4hash(rp, cr)];

        /*
         * Allocate now assuming that mostly an allocation will be
         * required.  This allows the allocation to happen without
         * holding the hash bucket locked.
         */
        nap = kmem_cache_alloc(acache4_cache, KM_NOSLEEP);
        if (nap != NULL) {
                nap->known = acc;
                nap->allowed = resacc;
                nap->rnode = rp;
                crhold(cr);
                nap->cred = cr;
                nap->hashq = hp;
        }

        rw_enter(&hp->lock, RW_WRITER);

        if (rp->r_acache != NULL) {
                ap = hp->next;
                while (ap != (acache4_t *)hp) {
                        if (crcmp(ap->cred, cr) == 0 && ap->rnode == rp) {
                                ap->known |= acc;
                                ap->allowed &= ~acc;
                                ap->allowed |= resacc;
                                rw_exit(&hp->lock);
                                if (nap != NULL) {
                                        crfree(nap->cred);
                                        kmem_cache_free(acache4_cache, nap);
                                }
                                return;
                        }
                        ap = ap->next;
                }
        }

        if (nap != NULL) {
#ifdef DEBUG
                clstat4_debug.access.value.ui64++;
#endif
                nap->next = hp->next;
                hp->next = nap;
                nap->next->prev = nap;
                nap->prev = (acache4_t *)hp;

                mutex_enter(&rp->r_statelock);
                nap->list = rp->r_acache;
                rp->r_acache = nap;
                mutex_exit(&rp->r_statelock);
        }

        rw_exit(&hp->lock);
}

int
nfs4_access_purge_rp(rnode4_t *rp)
{
        acache4_t *ap, *tmpap, *rplist;

        /*
         * If there aren't any cached entries, then there is nothing
         * to free.
         */
        if (rp->r_acache == NULL)
                return (0);

        mutex_enter(&rp->r_statelock);
        rplist = rp->r_acache;
        rp->r_acache = NULL;
        mutex_exit(&rp->r_statelock);

        /*
         * Loop through each entry in the list pointed to in the
         * rnode.  Remove each of these entries from the hash
         * queue that it is on and remove it from the list in
         * the rnode.
         */
        for (ap = rplist; ap != NULL; ap = tmpap) {
                rw_enter(&ap->hashq->lock, RW_WRITER);
                ap->prev->next = ap->next;
                ap->next->prev = ap->prev;
                rw_exit(&ap->hashq->lock);

                tmpap = ap->list;
                crfree(ap->cred);
                kmem_cache_free(acache4_cache, ap);
#ifdef DEBUG
                clstat4_debug.access.value.ui64--;
#endif
        }

        return (1);
}

int
nfs4_acache_init(void)
{
        extern int rtable4size;
        int i;

        /*
         * Initial guess is one access cache entry per rnode unless
         * nacache is set to a non-zero value and then it is used to
         * indicate a guess at the number of access cache entries.
         */
        if (nacache > 0)
                acache4size = 1 << highbit(nacache / acache4_hashlen);
        else
                acache4size = rtable4size;
        acache4mask = acache4size - 1;
        acache4 = kmem_alloc(acache4size * sizeof (*acache4), KM_SLEEP);
        for (i = 0; i < acache4size; i++) {
                acache4[i].next = (acache4_t *)&acache4[i];
                acache4[i].prev = (acache4_t *)&acache4[i];
                rw_init(&acache4[i].lock, NULL, RW_DEFAULT, NULL);
        }
        acache4_cache = kmem_cache_create("nfs4_access_cache",
            sizeof (acache4_t), 0, NULL, NULL, NULL, NULL, NULL, 0);

        return (0);
}

int
nfs4_acache_fini(void)
{
        int i;

        /*
         * Deallocated the access cache
         */
        kmem_cache_destroy(acache4_cache);

        for (i = 0; i < acache4size; i++)
                rw_destroy(&acache4[i].lock);
        kmem_free(acache4, acache4size * sizeof (*acache4));

        return (0);
}