/*
 * 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_node.c  8.6 (Berkeley) 5/22/95
 * $FreeBSD: src/sys/nfs/nfs_node.c,v 1.36.2.3 2002/01/05 22:25:04 dillon Exp $
 */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/fnv_hash.h>
#include <sys/objcache.h>

#include "rpcv2.h"
#include "nfsproto.h"
#include "nfs.h"
#include "nfsmount.h"
#include "nfsnode.h"

static struct lwkt_token nfsnhash_token =
                        LWKT_TOKEN_INITIALIZER(nfsnhash_token);
static struct lock nfsnhash_lock;
__read_mostly static LIST_HEAD(nfsnodehashhead, nfsnode) *nfsnodehashtbl;
__read_mostly static u_long nfsnodehash;

#define TRUE    1
#define FALSE   0

#define NFSNOHASH(fhsum)        (&nfsnodehashtbl[(fhsum) & nfsnodehash])

/*
 * Initialize hash links for nfsnodes
 * and build nfsnode free list.
 */
void
nfs_nhinit(void)
{
        int hsize = vfs_inodehashsize();

        nfsnodehashtbl = hashinit(hsize, M_NFS, &nfsnodehash);
        lockinit(&nfsnhash_lock, "nfsnht", 0, 0);
}

void
nfs_nhdestroy(void)
{
        hashdestroy(nfsnodehashtbl, M_NFS, nfsnodehash);
}

/*
 * Look up a vnode/nfsnode by file handle.
 * Callers must check for mount points!!
 * In all cases, a pointer to a
 * nfsnode structure is returned.
 */

int
nfs_nget(struct mount *mntp, nfsfh_t *fhp, int fhsize, struct nfsnode **npp,
         struct vnode *notvp)
{
        struct nfsnode *np, *np2;
        struct nfsnodehashhead *nhpp;
        struct vnode *vp;
        int error;
        int lkflags;
        struct nfsmount *nmp;

        /*
         * Calculate nfs mount point and figure out whether the rslock should
         * be interruptable or not.
         */
        nmp = VFSTONFS(mntp);
        if (nmp->nm_flag & NFSMNT_INT)
                lkflags = LK_PCATCH;
        else
                lkflags = 0;

        lwkt_gettoken(&nfsnhash_token);

retry:
        nhpp = NFSNOHASH(fnv_32_buf(fhp->fh_bytes, fhsize, FNV1_32_INIT));
loop:
        LIST_FOREACH(np, nhpp, n_hash) {
                if (mntp != NFSTOV(np)->v_mount || np->n_fhsize != fhsize ||
                    bcmp((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize)) {
                        continue;
                }
                vp = NFSTOV(np);
                if (vp == notvp) {
                        kprintf("nfs warning: client-client collision "
                                "during rename/link/softlink\n");
                        *npp = NULL;
                        lwkt_reltoken(&nfsnhash_token);
                        return (ESTALE);
                }
                if (vget(vp, LK_EXCLUSIVE))
                        goto loop;
                LIST_FOREACH(np, nhpp, n_hash) {
                        if (mntp == NFSTOV(np)->v_mount &&
                            np->n_fhsize == fhsize &&
                            bcmp((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize) == 0
                        ) {
                                break;
                        }
                }
                if (np == NULL || NFSTOV(np) != vp) {
                        vput(vp);
                        goto loop;
                }
                *npp = np;
                lwkt_reltoken(&nfsnhash_token);
                return(0);
        }

        /*
         * Obtain a lock to prevent a race condition if the getnewvnode()
         * or MALLOC() below happens to block.
         */
        if (lockmgr(&nfsnhash_lock, LK_EXCLUSIVE | LK_SLEEPFAIL))
                goto loop;

        /*
         * Allocate before getnewvnode since doing so afterward
         * might cause a bogus v_data pointer to get dereferenced
         * elsewhere if objcache should block.
         */
        np = kmalloc_obj(sizeof(struct nfsnode), nmp->nm_mnode,
                         M_WAITOK|M_ZERO);
                
        error = getnewvnode(VT_NFS, mntp, &vp, 0, 0);
        if (error) {
                lockmgr(&nfsnhash_lock, LK_RELEASE);
                *npp = NULL;
                kfree_obj(np, nmp->nm_mnode);
                lwkt_reltoken(&nfsnhash_token);
                return (error);
        }

        /*
         * Initialize most of (np).
         */
        bzero(np, sizeof (*np));
        if (fhsize > NFS_SMALLFH) {
                np->n_fhp = kmalloc(fhsize, M_NFSBIGFH, M_WAITOK);
        } else {
                np->n_fhp = &np->n_fh;
        }
        bcopy((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize);
        np->n_fhsize = fhsize;
        lockinit(&np->n_rslock, "nfrslk", 0, lkflags);

        /*
         * Validate that we did not race another nfs_nget() due to blocking
         * here and there.
         */
        for (np2 = nhpp->lh_first; np2 != NULL; np2 = np2->n_hash.le_next) {
                if (mntp != NFSTOV(np2)->v_mount || np2->n_fhsize != fhsize ||
                    bcmp((caddr_t)fhp, (caddr_t)np2->n_fhp, fhsize)) {
                        continue;
                }
                vx_put(vp);
                lockmgr(&nfsnhash_lock, LK_RELEASE);

                if (np->n_fhsize > NFS_SMALLFH)
                        kfree((caddr_t)np->n_fhp, M_NFSBIGFH);
                np->n_fhp = NULL;
                kfree_obj(np, nmp->nm_mnode);
                goto retry;
        }

        /*
         * Finish connecting up (np, vp) and insert the nfsnode in the
         * hash for its new file handle.
         *
         * nvp is locked & refd so effectively so is np.
         */
        np->n_vnode = vp;
        vp->v_data = np;
        LIST_INSERT_HEAD(nhpp, np, n_hash);
        *npp = np;
        lockmgr(&nfsnhash_lock, LK_RELEASE);
        lwkt_reltoken(&nfsnhash_token);
        vx_downgrade(vp);

        return (0);
}

/*
 * Nonblocking version of nfs_nget()
 */
int
nfs_nget_nonblock(struct mount *mntp, nfsfh_t *fhp, int fhsize,
                  struct nfsnode **npp, struct vnode *notvp)
{
        struct nfsnode *np, *np2;
        struct nfsnodehashhead *nhpp;
        struct vnode *vp;
        int error;
        int lkflags;
        struct nfsmount *nmp;

        /*
         * Calculate nfs mount point and figure out whether the rslock should
         * be interruptable or not.
         */
        nmp = VFSTONFS(mntp);
        if (nmp->nm_flag & NFSMNT_INT)
                lkflags = LK_PCATCH;
        else
                lkflags = 0;
        vp = NULL;
        *npp = NULL;

        lwkt_gettoken(&nfsnhash_token);

retry:
        nhpp = NFSNOHASH(fnv_32_buf(fhp->fh_bytes, fhsize, FNV1_32_INIT));
loop:
        LIST_FOREACH(np, nhpp, n_hash) {
                if (mntp != NFSTOV(np)->v_mount || np->n_fhsize != fhsize ||
                    bcmp((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize)) {
                        continue;
                }
                if (vp == NULL) {
                        vp = NFSTOV(np);
                        if (vp == notvp) {
                                kprintf("nfs warning: client-client collision "
                                        "during rename/link/softlink\n");
                                error = ESTALE;
                                goto fail;
                        }
                        if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT)) {
                                error = EWOULDBLOCK;
                                goto fail;
                        }
                        goto loop;
                }
                if (NFSTOV(np) != vp) {
                        vput(vp);
                        goto loop;
                }
                *npp = np;
                lwkt_reltoken(&nfsnhash_token);
                return(0);
        }

        /*
         * Not found.  If we raced and had acquired a vp we have to release
         * it here.
         */
        if (vp) {
                vput(vp);
                vp = NULL;
        }

        /*
         * Obtain a lock to prevent a race condition if the getnewvnode()
         * or MALLOC() below happens to block.
         */
        if (lockmgr(&nfsnhash_lock, LK_EXCLUSIVE | LK_SLEEPFAIL))
                goto loop;

        /*
         * Entry not found, allocate a new entry.
         *
         * Allocate before getnewvnode since doing so afterward
         * might cause a bogus v_data pointer to get dereferenced
         * elsewhere if objcache should block.
         */
        np = kmalloc_obj(sizeof(struct nfsnode), nmp->nm_mnode,
                         M_WAITOK|M_ZERO);

        error = getnewvnode(VT_NFS, mntp, &vp, 0, 0);
        if (error) {
                lockmgr(&nfsnhash_lock, LK_RELEASE);
                kfree_obj(np, nmp->nm_mnode);
                lwkt_reltoken(&nfsnhash_token);
                return (error);
        }

        /*
         * Initialize most of (np).
         */
        bzero(np, sizeof (*np));
        if (fhsize > NFS_SMALLFH) {
                np->n_fhp = kmalloc(fhsize, M_NFSBIGFH, M_WAITOK);
        } else {
                np->n_fhp = &np->n_fh;
        }
        bcopy((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize);
        np->n_fhsize = fhsize;
        lockinit(&np->n_rslock, "nfrslk", 0, lkflags);

        /*
         * Validate that we did not race another nfs_nget() due to blocking
         * here and there.
         */
        for (np2 = nhpp->lh_first; np2 != NULL; np2 = np2->n_hash.le_next) {
                if (mntp != NFSTOV(np2)->v_mount || np2->n_fhsize != fhsize ||
                    bcmp((caddr_t)fhp, (caddr_t)np2->n_fhp, fhsize)) {
                        continue;
                }
                vx_put(vp);
                lockmgr(&nfsnhash_lock, LK_RELEASE);

                if (np->n_fhsize > NFS_SMALLFH)
                        kfree((caddr_t)np->n_fhp, M_NFSBIGFH);
                np->n_fhp = NULL;
                kfree_obj(np, nmp->nm_mnode);

                /*
                 * vp state is retained on retry/loop so we must NULL it
                 * out here or fireworks may ensue.
                 */
                vp = NULL;
                goto retry;
        }

        /*
         * Finish connecting up (np, vp) and insert the nfsnode in the
         * hash for its new file handle.
         *
         * nvp is locked & refd so effectively so is np.
         */
        np->n_vnode = vp;
        vp->v_data = np;
        LIST_INSERT_HEAD(nhpp, np, n_hash);

        /*
         * nvp is locked & refd so effectively so is np.
         */
        *npp = np;
        error = 0;
        lockmgr(&nfsnhash_lock, LK_RELEASE);
        vx_downgrade(vp);
fail:
        lwkt_reltoken(&nfsnhash_token);
        return (error);
}

/*
 * nfs_inactive(struct vnode *a_vp)
 *
 * NOTE: the passed vnode is locked but not referenced.  On return the
 * vnode must be unlocked and not referenced.
 */
int
nfs_inactive(struct vop_inactive_args *ap)
{
        struct nfsmount *nmp = VFSTONFS(ap->a_vp->v_mount);
        struct nfsnode *np;
        struct sillyrename *sp;

        lwkt_gettoken(&nmp->nm_token);

        np = VTONFS(ap->a_vp);
        if (prtactive && VREFCNT(ap->a_vp) > 1)
                vprint("nfs_inactive: pushing active", ap->a_vp);
        if (ap->a_vp->v_type != VDIR) {
                sp = np->n_sillyrename;
                np->n_sillyrename = NULL;
        } else {
                sp = NULL;
        }
        if (sp) {
                /*
                 * We need a reference to keep the vnode from being
                 * recycled by getnewvnode while we do the I/O
                 * associated with discarding the buffers.  The vnode
                 * is already locked.
                 */
                nfs_vinvalbuf(ap->a_vp, 0, 1);

                /*
                 * Remove the silly file that was rename'd earlier
                 */
                nfs_removeit(sp);
                crfree(sp->s_cred);
                vrele(sp->s_dvp);
                kfree((caddr_t)sp, M_NFSREQ);
        }

        np->n_flag &= ~(NWRITEERR | NACC | NUPD | NCHG | NLOCKED | NWANTED);
        if (np->n_flag & NREMOVED)
                vrecycle(ap->a_vp);
        lwkt_reltoken(&nmp->nm_token);

        return (0);
}

/*
 * Reclaim an nfsnode so that it can be used for other purposes.
 *
 * There should be no direct references to the related nfs node
 * since nobody is holding the vnode any more, other than hash
 * lookups which are interlocked against nfsnhash_token and vget().
 *
 * nfs_reclaim(struct vnode *a_vp)
 */
int
nfs_reclaim(struct vop_reclaim_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct nfsnode *np = VTONFS(vp);
        struct nfsdmap *dp, *dp2;
        struct nfsmount *nmp = VFSTONFS(vp->v_mount);

        if (prtactive && VREFCNT(vp) > 1)
                vprint("nfs_reclaim: pushing active", vp);


        /*
         * Remove from hash table and remove the cross links.
         *
         * NOTE: Other NFS code may look up a np and vget() the
         *       related vnode, then will check np->n_vnode.
         *       We must clear np->n_vnode here to ensure that all
         *       possible races are dealt with.
         */
        lwkt_gettoken(&nfsnhash_token);
        KKASSERT(np->n_vnode == vp);
        if (np->n_hash.le_prev != NULL)
                LIST_REMOVE(np, n_hash);
        np->n_vnode = NULL;
        vp->v_data = NULL;
        lwkt_reltoken(&nfsnhash_token);

        /*
         * Free up any directory cookie structures and
         * large file handle structures that might be associated with
         * this nfs node.
         */
        if (vp->v_type == VDIR) {
                dp = np->n_cookies.lh_first;
                while (dp) {
                        dp2 = dp;
                        dp = dp->ndm_list.le_next;
                        kfree((caddr_t)dp2, M_NFSDIROFF);
                }
        }
        if (np->n_fhsize > NFS_SMALLFH) {
                kfree((caddr_t)np->n_fhp, M_NFSBIGFH);
        }
        if (np->n_rucred) {
                crfree(np->n_rucred);
                np->n_rucred = NULL;
        }
        if (np->n_wucred) {
                crfree(np->n_wucred);
                np->n_wucred = NULL;
        }
        kfree_obj(np, nmp->nm_mnode);

        return (0);
}