// SPDX-License-Identifier: GPL-2.0
/*
 * XDR support for nfsd/protocol version 3.
 *
 * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
 *
 * 2003-08-09 Jamie Lokier: Use htonl() for nanoseconds, not htons()!
 */

#include <linux/namei.h>
#include <linux/sunrpc/svc_xprt.h>
#include "xdr3.h"
#include "auth.h"
#include "netns.h"
#include "vfs.h"

#define NFSDDBG_FACILITY                NFSDDBG_XDR


/*
 * Mapping of S_IF* types to NFS file types
 */
static u32      nfs3_ftypes[] = {
        NF3NON,  NF3FIFO, NF3CHR, NF3BAD,
        NF3DIR,  NF3BAD,  NF3BLK, NF3BAD,
        NF3REG,  NF3BAD,  NF3LNK, NF3BAD,
        NF3SOCK, NF3BAD,  NF3LNK, NF3BAD,
};


/*
 * XDR functions for basic NFS types
 */
static __be32 *
encode_time3(__be32 *p, struct timespec64 *time)
{
        *p++ = htonl((u32) time->tv_sec); *p++ = htonl(time->tv_nsec);
        return p;
}

static __be32 *
decode_time3(__be32 *p, struct timespec64 *time)
{
        time->tv_sec = ntohl(*p++);
        time->tv_nsec = ntohl(*p++);
        return p;
}

static __be32 *
decode_fh(__be32 *p, struct svc_fh *fhp)
{
        unsigned int size;
        fh_init(fhp, NFS3_FHSIZE);
        size = ntohl(*p++);
        if (size > NFS3_FHSIZE)
                return NULL;

        memcpy(&fhp->fh_handle.fh_base, p, size);
        fhp->fh_handle.fh_size = size;
        return p + XDR_QUADLEN(size);
}

/* Helper function for NFSv3 ACL code */
__be32 *nfs3svc_decode_fh(__be32 *p, struct svc_fh *fhp)
{
        return decode_fh(p, fhp);
}

static __be32 *
encode_fh(__be32 *p, struct svc_fh *fhp)
{
        unsigned int size = fhp->fh_handle.fh_size;
        *p++ = htonl(size);
        if (size) p[XDR_QUADLEN(size)-1]=0;
        memcpy(p, &fhp->fh_handle.fh_base, size);
        return p + XDR_QUADLEN(size);
}

/*
 * Decode a file name and make sure that the path contains
 * no slashes or null bytes.
 */
static __be32 *
decode_filename(__be32 *p, char **namp, unsigned int *lenp)
{
        char            *name;
        unsigned int    i;

        if ((p = xdr_decode_string_inplace(p, namp, lenp, NFS3_MAXNAMLEN)) != NULL) {
                for (i = 0, name = *namp; i < *lenp; i++, name++) {
                        if (*name == '\0' || *name == '/')
                                return NULL;
                }
        }

        return p;
}

static __be32 *
decode_sattr3(__be32 *p, struct iattr *iap, struct user_namespace *userns)
{
        u32     tmp;

        iap->ia_valid = 0;

        if (*p++) {
                iap->ia_valid |= ATTR_MODE;
                iap->ia_mode = ntohl(*p++);
        }
        if (*p++) {
                iap->ia_uid = make_kuid(userns, ntohl(*p++));
                if (uid_valid(iap->ia_uid))
                        iap->ia_valid |= ATTR_UID;
        }
        if (*p++) {
                iap->ia_gid = make_kgid(userns, ntohl(*p++));
                if (gid_valid(iap->ia_gid))
                        iap->ia_valid |= ATTR_GID;
        }
        if (*p++) {
                u64     newsize;

                iap->ia_valid |= ATTR_SIZE;
                p = xdr_decode_hyper(p, &newsize);
                iap->ia_size = min_t(u64, newsize, NFS_OFFSET_MAX);
        }
        if ((tmp = ntohl(*p++)) == 1) { /* set to server time */
                iap->ia_valid |= ATTR_ATIME;
        } else if (tmp == 2) {          /* set to client time */
                iap->ia_valid |= ATTR_ATIME | ATTR_ATIME_SET;
                iap->ia_atime.tv_sec = ntohl(*p++);
                iap->ia_atime.tv_nsec = ntohl(*p++);
        }
        if ((tmp = ntohl(*p++)) == 1) { /* set to server time */
                iap->ia_valid |= ATTR_MTIME;
        } else if (tmp == 2) {          /* set to client time */
                iap->ia_valid |= ATTR_MTIME | ATTR_MTIME_SET;
                iap->ia_mtime.tv_sec = ntohl(*p++);
                iap->ia_mtime.tv_nsec = ntohl(*p++);
        }
        return p;
}

static __be32 *encode_fsid(__be32 *p, struct svc_fh *fhp)
{
        u64 f;
        switch(fsid_source(fhp)) {
        default:
        case FSIDSOURCE_DEV:
                p = xdr_encode_hyper(p, (u64)huge_encode_dev
                                     (fhp->fh_dentry->d_sb->s_dev));
                break;
        case FSIDSOURCE_FSID:
                p = xdr_encode_hyper(p, (u64) fhp->fh_export->ex_fsid);
                break;
        case FSIDSOURCE_UUID:
                f = ((u64*)fhp->fh_export->ex_uuid)[0];
                f ^= ((u64*)fhp->fh_export->ex_uuid)[1];
                p = xdr_encode_hyper(p, f);
                break;
        }
        return p;
}

static __be32 *
encode_fattr3(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp,
              struct kstat *stat)
{
        struct user_namespace *userns = nfsd_user_namespace(rqstp);
        *p++ = htonl(nfs3_ftypes[(stat->mode & S_IFMT) >> 12]);
        *p++ = htonl((u32) (stat->mode & S_IALLUGO));
        *p++ = htonl((u32) stat->nlink);
        *p++ = htonl((u32) from_kuid_munged(userns, stat->uid));
        *p++ = htonl((u32) from_kgid_munged(userns, stat->gid));
        if (S_ISLNK(stat->mode) && stat->size > NFS3_MAXPATHLEN) {
                p = xdr_encode_hyper(p, (u64) NFS3_MAXPATHLEN);
        } else {
                p = xdr_encode_hyper(p, (u64) stat->size);
        }
        p = xdr_encode_hyper(p, ((u64)stat->blocks) << 9);
        *p++ = htonl((u32) MAJOR(stat->rdev));
        *p++ = htonl((u32) MINOR(stat->rdev));
        p = encode_fsid(p, fhp);
        p = xdr_encode_hyper(p, stat->ino);
        p = encode_time3(p, &stat->atime);
        p = encode_time3(p, &stat->mtime);
        p = encode_time3(p, &stat->ctime);

        return p;
}

static __be32 *
encode_saved_post_attr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp)
{
        /* Attributes to follow */
        *p++ = xdr_one;
        return encode_fattr3(rqstp, p, fhp, &fhp->fh_post_attr);
}

/*
 * Encode post-operation attributes.
 * The inode may be NULL if the call failed because of a stale file
 * handle. In this case, no attributes are returned.
 */
static __be32 *
encode_post_op_attr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp)
{
        struct dentry *dentry = fhp->fh_dentry;
        if (dentry && d_really_is_positive(dentry)) {
                __be32 err;
                struct kstat stat;

                err = fh_getattr(fhp, &stat);
                if (!err) {
                        *p++ = xdr_one;         /* attributes follow */
                        lease_get_mtime(d_inode(dentry), &stat.mtime);
                        return encode_fattr3(rqstp, p, fhp, &stat);
                }
        }
        *p++ = xdr_zero;
        return p;
}

/* Helper for NFSv3 ACLs */
__be32 *
nfs3svc_encode_post_op_attr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp)
{
        return encode_post_op_attr(rqstp, p, fhp);
}

/*
 * Enocde weak cache consistency data
 */
static __be32 *
encode_wcc_data(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp)
{
        struct dentry   *dentry = fhp->fh_dentry;

        if (dentry && d_really_is_positive(dentry) && fhp->fh_post_saved) {
                if (fhp->fh_pre_saved) {
                        *p++ = xdr_one;
                        p = xdr_encode_hyper(p, (u64) fhp->fh_pre_size);
                        p = encode_time3(p, &fhp->fh_pre_mtime);
                        p = encode_time3(p, &fhp->fh_pre_ctime);
                } else {
                        *p++ = xdr_zero;
                }
                return encode_saved_post_attr(rqstp, p, fhp);
        }
        /* no pre- or post-attrs */
        *p++ = xdr_zero;
        return encode_post_op_attr(rqstp, p, fhp);
}

/*
 * Fill in the pre_op attr for the wcc data
 */
void fill_pre_wcc(struct svc_fh *fhp)
{
        struct inode    *inode;
        struct kstat    stat;
        __be32 err;

        if (fhp->fh_pre_saved)
                return;

        inode = d_inode(fhp->fh_dentry);
        err = fh_getattr(fhp, &stat);
        if (err) {
                /* Grab the times from inode anyway */
                stat.mtime = inode->i_mtime;
                stat.ctime = inode->i_ctime;
                stat.size  = inode->i_size;
        }

        fhp->fh_pre_mtime = stat.mtime;
        fhp->fh_pre_ctime = stat.ctime;
        fhp->fh_pre_size  = stat.size;
        fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode);
        fhp->fh_pre_saved = true;
}

/*
 * Fill in the post_op attr for the wcc data
 */
void fill_post_wcc(struct svc_fh *fhp)
{
        __be32 err;

        if (fhp->fh_post_saved)
                printk("nfsd: inode locked twice during operation.\n");

        err = fh_getattr(fhp, &fhp->fh_post_attr);
        fhp->fh_post_change = nfsd4_change_attribute(&fhp->fh_post_attr,
                                                     d_inode(fhp->fh_dentry));
        if (err) {
                fhp->fh_post_saved = false;
                /* Grab the ctime anyway - set_change_info might use it */
                fhp->fh_post_attr.ctime = d_inode(fhp->fh_dentry)->i_ctime;
        } else
                fhp->fh_post_saved = true;
}

/*
 * XDR decode functions
 */
int
nfs3svc_decode_fhandle(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd_fhandle *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_sattrargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_sattrargs *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = decode_sattr3(p, &args->attrs, nfsd_user_namespace(rqstp));

        if ((args->check_guard = ntohl(*p++)) != 0) { 
                struct timespec64 time;
                p = decode_time3(p, &time);
                args->guardtime = time.tv_sec;
        }

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_diropargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_diropargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->fh))
         || !(p = decode_filename(p, &args->name, &args->len)))
                return 0;

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_accessargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_accessargs *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        args->access = ntohl(*p++);

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readargs *args = rqstp->rq_argp;
        unsigned int len;
        int v;
        u32 max_blocksize = svc_max_payload(rqstp);

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = xdr_decode_hyper(p, &args->offset);

        args->count = ntohl(*p++);
        len = min(args->count, max_blocksize);

        /* set up the kvec */
        v=0;
        while (len > 0) {
                struct page *p = *(rqstp->rq_next_page++);

                rqstp->rq_vec[v].iov_base = page_address(p);
                rqstp->rq_vec[v].iov_len = min_t(unsigned int, len, PAGE_SIZE);
                len -= rqstp->rq_vec[v].iov_len;
                v++;
        }
        args->vlen = v;
        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_writeargs *args = rqstp->rq_argp;
        unsigned int len, hdr, dlen;
        u32 max_blocksize = svc_max_payload(rqstp);
        struct kvec *head = rqstp->rq_arg.head;
        struct kvec *tail = rqstp->rq_arg.tail;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = xdr_decode_hyper(p, &args->offset);

        args->count = ntohl(*p++);
        args->stable = ntohl(*p++);
        len = args->len = ntohl(*p++);
        if ((void *)p > head->iov_base + head->iov_len)
                return 0;
        /*
         * The count must equal the amount of data passed.
         */
        if (args->count != args->len)
                return 0;

        /*
         * Check to make sure that we got the right number of
         * bytes.
         */
        hdr = (void*)p - head->iov_base;
        dlen = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len - hdr;
        /*
         * Round the length of the data which was specified up to
         * the next multiple of XDR units and then compare that
         * against the length which was actually received.
         * Note that when RPCSEC/GSS (for example) is used, the
         * data buffer can be padded so dlen might be larger
         * than required.  It must never be smaller.
         */
        if (dlen < XDR_QUADLEN(len)*4)
                return 0;

        if (args->count > max_blocksize) {
                args->count = max_blocksize;
                len = args->len = max_blocksize;
        }

        args->first.iov_base = (void *)p;
        args->first.iov_len = head->iov_len - hdr;
        return 1;
}

int
nfs3svc_decode_createargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_createargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->fh))
         || !(p = decode_filename(p, &args->name, &args->len)))
                return 0;

        switch (args->createmode = ntohl(*p++)) {
        case NFS3_CREATE_UNCHECKED:
        case NFS3_CREATE_GUARDED:
                p = decode_sattr3(p, &args->attrs, nfsd_user_namespace(rqstp));
                break;
        case NFS3_CREATE_EXCLUSIVE:
                args->verf = p;
                p += 2;
                break;
        default:
                return 0;
        }

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_mkdirargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_createargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->fh)) ||
            !(p = decode_filename(p, &args->name, &args->len)))
                return 0;
        p = decode_sattr3(p, &args->attrs, nfsd_user_namespace(rqstp));

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_symlinkargs *args = rqstp->rq_argp;
        char *base = (char *)p;
        size_t dlen;

        if (!(p = decode_fh(p, &args->ffh)) ||
            !(p = decode_filename(p, &args->fname, &args->flen)))
                return 0;
        p = decode_sattr3(p, &args->attrs, nfsd_user_namespace(rqstp));

        args->tlen = ntohl(*p++);

        args->first.iov_base = p;
        args->first.iov_len = rqstp->rq_arg.head[0].iov_len;
        args->first.iov_len -= (char *)p - base;

        dlen = args->first.iov_len + rqstp->rq_arg.page_len +
               rqstp->rq_arg.tail[0].iov_len;
        if (dlen < XDR_QUADLEN(args->tlen) << 2)
                return 0;
        return 1;
}

int
nfs3svc_decode_mknodargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_mknodargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->fh))
         || !(p = decode_filename(p, &args->name, &args->len)))
                return 0;

        args->ftype = ntohl(*p++);

        if (args->ftype == NF3BLK  || args->ftype == NF3CHR
         || args->ftype == NF3SOCK || args->ftype == NF3FIFO)
                p = decode_sattr3(p, &args->attrs, nfsd_user_namespace(rqstp));

        if (args->ftype == NF3BLK || args->ftype == NF3CHR) {
                args->major = ntohl(*p++);
                args->minor = ntohl(*p++);
        }

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_renameargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_renameargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->ffh))
         || !(p = decode_filename(p, &args->fname, &args->flen))
         || !(p = decode_fh(p, &args->tfh))
         || !(p = decode_filename(p, &args->tname, &args->tlen)))
                return 0;

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_readlinkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readlinkargs *args = rqstp->rq_argp;

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        args->buffer = page_address(*(rqstp->rq_next_page++));

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_linkargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_linkargs *args = rqstp->rq_argp;

        if (!(p = decode_fh(p, &args->ffh))
         || !(p = decode_fh(p, &args->tfh))
         || !(p = decode_filename(p, &args->tname, &args->tlen)))
                return 0;

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readdirargs *args = rqstp->rq_argp;
        int len;
        u32 max_blocksize = svc_max_payload(rqstp);

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = xdr_decode_hyper(p, &args->cookie);
        args->verf   = p; p += 2;
        args->dircount = ~0;
        args->count  = ntohl(*p++);
        len = args->count  = min_t(u32, args->count, max_blocksize);

        while (len > 0) {
                struct page *p = *(rqstp->rq_next_page++);
                if (!args->buffer)
                        args->buffer = page_address(p);
                len -= PAGE_SIZE;
        }

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readdirargs *args = rqstp->rq_argp;
        int len;
        u32 max_blocksize = svc_max_payload(rqstp);

        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = xdr_decode_hyper(p, &args->cookie);
        args->verf     = p; p += 2;
        args->dircount = ntohl(*p++);
        args->count    = ntohl(*p++);

        len = args->count = min(args->count, max_blocksize);
        while (len > 0) {
                struct page *p = *(rqstp->rq_next_page++);
                if (!args->buffer)
                        args->buffer = page_address(p);
                len -= PAGE_SIZE;
        }

        return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_commitargs(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_commitargs *args = rqstp->rq_argp;
        p = decode_fh(p, &args->fh);
        if (!p)
                return 0;
        p = xdr_decode_hyper(p, &args->offset);
        args->count = ntohl(*p++);

        return xdr_argsize_check(rqstp, p);
}

/*
 * XDR encode functions
 */
/*
 * There must be an encoding function for void results so svc_process
 * will work properly.
 */
int
nfs3svc_encode_voidres(struct svc_rqst *rqstp, __be32 *p)
{
        return xdr_ressize_check(rqstp, p);
}

/* GETATTR */
int
nfs3svc_encode_attrstat(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_attrstat *resp = rqstp->rq_resp;

        if (resp->status == 0) {
                lease_get_mtime(d_inode(resp->fh.fh_dentry),
                                &resp->stat.mtime);
                p = encode_fattr3(rqstp, p, &resp->fh, &resp->stat);
        }
        return xdr_ressize_check(rqstp, p);
}

/* SETATTR, REMOVE, RMDIR */
int
nfs3svc_encode_wccstat(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_attrstat *resp = rqstp->rq_resp;

        p = encode_wcc_data(rqstp, p, &resp->fh);
        return xdr_ressize_check(rqstp, p);
}

/* LOOKUP */
int
nfs3svc_encode_diropres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_diropres *resp = rqstp->rq_resp;

        if (resp->status == 0) {
                p = encode_fh(p, &resp->fh);
                p = encode_post_op_attr(rqstp, p, &resp->fh);
        }
        p = encode_post_op_attr(rqstp, p, &resp->dirfh);
        return xdr_ressize_check(rqstp, p);
}

/* ACCESS */
int
nfs3svc_encode_accessres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_accessres *resp = rqstp->rq_resp;

        p = encode_post_op_attr(rqstp, p, &resp->fh);
        if (resp->status == 0)
                *p++ = htonl(resp->access);
        return xdr_ressize_check(rqstp, p);
}

/* READLINK */
int
nfs3svc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readlinkres *resp = rqstp->rq_resp;

        p = encode_post_op_attr(rqstp, p, &resp->fh);
        if (resp->status == 0) {
                *p++ = htonl(resp->len);
                xdr_ressize_check(rqstp, p);
                rqstp->rq_res.page_len = resp->len;
                if (resp->len & 3) {
                        /* need to pad the tail */
                        rqstp->rq_res.tail[0].iov_base = p;
                        *p = 0;
                        rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
                }
                return 1;
        } else
                return xdr_ressize_check(rqstp, p);
}

/* READ */
int
nfs3svc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readres *resp = rqstp->rq_resp;

        p = encode_post_op_attr(rqstp, p, &resp->fh);
        if (resp->status == 0) {
                *p++ = htonl(resp->count);
                *p++ = htonl(resp->eof);
                *p++ = htonl(resp->count);      /* xdr opaque count */
                xdr_ressize_check(rqstp, p);
                /* now update rqstp->rq_res to reflect data as well */
                rqstp->rq_res.page_len = resp->count;
                if (resp->count & 3) {
                        /* need to pad the tail */
                        rqstp->rq_res.tail[0].iov_base = p;
                        *p = 0;
                        rqstp->rq_res.tail[0].iov_len = 4 - (resp->count & 3);
                }
                return 1;
        } else
                return xdr_ressize_check(rqstp, p);
}

/* WRITE */
int
nfs3svc_encode_writeres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_writeres *resp = rqstp->rq_resp;

        p = encode_wcc_data(rqstp, p, &resp->fh);
        if (resp->status == 0) {
                *p++ = htonl(resp->count);
                *p++ = htonl(resp->committed);
                *p++ = resp->verf[0];
                *p++ = resp->verf[1];
        }
        return xdr_ressize_check(rqstp, p);
}

/* CREATE, MKDIR, SYMLINK, MKNOD */
int
nfs3svc_encode_createres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_diropres *resp = rqstp->rq_resp;

        if (resp->status == 0) {
                *p++ = xdr_one;
                p = encode_fh(p, &resp->fh);
                p = encode_post_op_attr(rqstp, p, &resp->fh);
        }
        p = encode_wcc_data(rqstp, p, &resp->dirfh);
        return xdr_ressize_check(rqstp, p);
}

/* RENAME */
int
nfs3svc_encode_renameres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_renameres *resp = rqstp->rq_resp;

        p = encode_wcc_data(rqstp, p, &resp->ffh);
        p = encode_wcc_data(rqstp, p, &resp->tfh);
        return xdr_ressize_check(rqstp, p);
}

/* LINK */
int
nfs3svc_encode_linkres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_linkres *resp = rqstp->rq_resp;

        p = encode_post_op_attr(rqstp, p, &resp->fh);
        p = encode_wcc_data(rqstp, p, &resp->tfh);
        return xdr_ressize_check(rqstp, p);
}

/* READDIR */
int
nfs3svc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_readdirres *resp = rqstp->rq_resp;

        p = encode_post_op_attr(rqstp, p, &resp->fh);

        if (resp->status == 0) {
                /* stupid readdir cookie */
                memcpy(p, resp->verf, 8); p += 2;
                xdr_ressize_check(rqstp, p);
                if (rqstp->rq_res.head[0].iov_len + (2<<2) > PAGE_SIZE)
                        return 1; /*No room for trailer */
                rqstp->rq_res.page_len = (resp->count) << 2;

                /* add the 'tail' to the end of the 'head' page - page 0. */
                rqstp->rq_res.tail[0].iov_base = p;
                *p++ = 0;               /* no more entries */
                *p++ = htonl(resp->common.err == nfserr_eof);
                rqstp->rq_res.tail[0].iov_len = 2<<2;
                return 1;
        } else
                return xdr_ressize_check(rqstp, p);
}

static __be32 *
encode_entry_baggage(struct nfsd3_readdirres *cd, __be32 *p, const char *name,
             int namlen, u64 ino)
{
        *p++ = xdr_one;                          /* mark entry present */
        p    = xdr_encode_hyper(p, ino);         /* file id */
        p    = xdr_encode_array(p, name, namlen);/* name length & name */

        cd->offset = p;                         /* remember pointer */
        p = xdr_encode_hyper(p, NFS_OFFSET_MAX);/* offset of next entry */

        return p;
}

static __be32
compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
                 const char *name, int namlen, u64 ino)
{
        struct svc_export       *exp;
        struct dentry           *dparent, *dchild;
        __be32 rv = nfserr_noent;

        dparent = cd->fh.fh_dentry;
        exp  = cd->fh.fh_export;

        if (isdotent(name, namlen)) {
                if (namlen == 2) {
                        dchild = dget_parent(dparent);
                        /* filesystem root - cannot return filehandle for ".." */
                        if (dchild == dparent)
                                goto out;
                } else
                        dchild = dget(dparent);
        } else
                dchild = lookup_positive_unlocked(name, dparent, namlen);
        if (IS_ERR(dchild))
                return rv;
        if (d_mountpoint(dchild))
                goto out;
        if (dchild->d_inode->i_ino != ino)
                goto out;
        rv = fh_compose(fhp, exp, dchild, &cd->fh);
out:
        dput(dchild);
        return rv;
}

static __be32 *encode_entryplus_baggage(struct nfsd3_readdirres *cd, __be32 *p, const char *name, int namlen, u64 ino)
{
        struct svc_fh   *fh = &cd->scratch;
        __be32 err;

        fh_init(fh, NFS3_FHSIZE);
        err = compose_entry_fh(cd, fh, name, namlen, ino);
        if (err) {
                *p++ = 0;
                *p++ = 0;
                goto out;
        }
        p = encode_post_op_attr(cd->rqstp, p, fh);
        *p++ = xdr_one;                 /* yes, a file handle follows */
        p = encode_fh(p, fh);
out:
        fh_put(fh);
        return p;
}

/*
 * Encode a directory entry. This one works for both normal readdir
 * and readdirplus.
 * The normal readdir reply requires 2 (fileid) + 1 (stringlen)
 * + string + 2 (cookie) + 1 (next) words, i.e. 6 + strlen.
 * 
 * The readdirplus baggage is 1+21 words for post_op_attr, plus the
 * file handle.
 */

#define NFS3_ENTRY_BAGGAGE      (2 + 1 + 2 + 1)
#define NFS3_ENTRYPLUS_BAGGAGE  (1 + 21 + 1 + (NFS3_FHSIZE >> 2))
static int
encode_entry(struct readdir_cd *ccd, const char *name, int namlen,
             loff_t offset, u64 ino, unsigned int d_type, int plus)
{
        struct nfsd3_readdirres *cd = container_of(ccd, struct nfsd3_readdirres,
                                                        common);
        __be32          *p = cd->buffer;
        caddr_t         curr_page_addr = NULL;
        struct page **  page;
        int             slen;           /* string (name) length */
        int             elen;           /* estimated entry length in words */
        int             num_entry_words = 0;    /* actual number of words */

        if (cd->offset) {
                u64 offset64 = offset;

                if (unlikely(cd->offset1)) {
                        /* we ended up with offset on a page boundary */
                        *cd->offset = htonl(offset64 >> 32);
                        *cd->offset1 = htonl(offset64 & 0xffffffff);
                        cd->offset1 = NULL;
                } else {
                        xdr_encode_hyper(cd->offset, offset64);
                }
                cd->offset = NULL;
        }

        /*
        dprintk("encode_entry(%.*s @%ld%s)\n",
                namlen, name, (long) offset, plus? " plus" : "");
         */

        /* truncate filename if too long */
        namlen = min(namlen, NFS3_MAXNAMLEN);

        slen = XDR_QUADLEN(namlen);
        elen = slen + NFS3_ENTRY_BAGGAGE
                + (plus? NFS3_ENTRYPLUS_BAGGAGE : 0);

        if (cd->buflen < elen) {
                cd->common.err = nfserr_toosmall;
                return -EINVAL;
        }

        /* determine which page in rq_respages[] we are currently filling */
        for (page = cd->rqstp->rq_respages + 1;
                                page < cd->rqstp->rq_next_page; page++) {
                curr_page_addr = page_address(*page);

                if (((caddr_t)cd->buffer >= curr_page_addr) &&
                    ((caddr_t)cd->buffer <  curr_page_addr + PAGE_SIZE))
                        break;
        }

        if ((caddr_t)(cd->buffer + elen) < (curr_page_addr + PAGE_SIZE)) {
                /* encode entry in current page */

                p = encode_entry_baggage(cd, p, name, namlen, ino);

                if (plus)
                        p = encode_entryplus_baggage(cd, p, name, namlen, ino);
                num_entry_words = p - cd->buffer;
        } else if (*(page+1) != NULL) {
                /* temporarily encode entry into next page, then move back to
                 * current and next page in rq_respages[] */
                __be32 *p1, *tmp;
                int len1, len2;

                /* grab next page for temporary storage of entry */
                p1 = tmp = page_address(*(page+1));

                p1 = encode_entry_baggage(cd, p1, name, namlen, ino);

                if (plus)
                        p1 = encode_entryplus_baggage(cd, p1, name, namlen, ino);

                /* determine entry word length and lengths to go in pages */
                num_entry_words = p1 - tmp;
                len1 = curr_page_addr + PAGE_SIZE - (caddr_t)cd->buffer;
                if ((num_entry_words << 2) < len1) {
                        /* the actual number of words in the entry is less
                         * than elen and can still fit in the current page
                         */
                        memmove(p, tmp, num_entry_words << 2);
                        p += num_entry_words;

                        /* update offset */
                        cd->offset = cd->buffer + (cd->offset - tmp);
                } else {
                        unsigned int offset_r = (cd->offset - tmp) << 2;

                        /* update pointer to offset location.
                         * This is a 64bit quantity, so we need to
                         * deal with 3 cases:
                         *  -   entirely in first page
                         *  -   entirely in second page
                         *  -   4 bytes in each page
                         */

                        if (offset_r + 8 <= len1) {
                                cd->offset = p + (cd->offset - tmp);
                        } else if (offset_r >= len1) {
                                cd->offset -= len1 >> 2;
                        } else {
                                /* sitting on the fence */
                                BUG_ON(offset_r != len1 - 4);
                                cd->offset = p + (cd->offset - tmp);
                                cd->offset1 = tmp;
                        }

                        len2 = (num_entry_words << 2) - len1;

                        /* move from temp page to current and next pages */
                        memmove(p, tmp, len1);
                        memmove(tmp, (caddr_t)tmp+len1, len2);

                        p = tmp + (len2 >> 2);
                }
        }
        else {
                cd->common.err = nfserr_toosmall;
                return -EINVAL;
        }

        cd->buflen -= num_entry_words;
        cd->buffer = p;
        cd->common.err = nfs_ok;
        return 0;

}

int
nfs3svc_encode_entry(void *cd, const char *name,
                     int namlen, loff_t offset, u64 ino, unsigned int d_type)
{
        return encode_entry(cd, name, namlen, offset, ino, d_type, 0);
}

int
nfs3svc_encode_entry_plus(void *cd, const char *name,
                          int namlen, loff_t offset, u64 ino,
                          unsigned int d_type)
{
        return encode_entry(cd, name, namlen, offset, ino, d_type, 1);
}

/* FSSTAT */
int
nfs3svc_encode_fsstatres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_fsstatres *resp = rqstp->rq_resp;
        struct kstatfs  *s = &resp->stats;
        u64             bs = s->f_bsize;

        *p++ = xdr_zero;        /* no post_op_attr */

        if (resp->status == 0) {
                p = xdr_encode_hyper(p, bs * s->f_blocks);      /* total bytes */
                p = xdr_encode_hyper(p, bs * s->f_bfree);       /* free bytes */
                p = xdr_encode_hyper(p, bs * s->f_bavail);      /* user available bytes */
                p = xdr_encode_hyper(p, s->f_files);    /* total inodes */
                p = xdr_encode_hyper(p, s->f_ffree);    /* free inodes */
                p = xdr_encode_hyper(p, s->f_ffree);    /* user available inodes */
                *p++ = htonl(resp->invarsec);   /* mean unchanged time */
        }
        return xdr_ressize_check(rqstp, p);
}

/* FSINFO */
int
nfs3svc_encode_fsinfores(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_fsinfores *resp = rqstp->rq_resp;

        *p++ = xdr_zero;        /* no post_op_attr */

        if (resp->status == 0) {
                *p++ = htonl(resp->f_rtmax);
                *p++ = htonl(resp->f_rtpref);
                *p++ = htonl(resp->f_rtmult);
                *p++ = htonl(resp->f_wtmax);
                *p++ = htonl(resp->f_wtpref);
                *p++ = htonl(resp->f_wtmult);
                *p++ = htonl(resp->f_dtpref);
                p = xdr_encode_hyper(p, resp->f_maxfilesize);
                *p++ = xdr_one;
                *p++ = xdr_zero;
                *p++ = htonl(resp->f_properties);
        }

        return xdr_ressize_check(rqstp, p);
}

/* PATHCONF */
int
nfs3svc_encode_pathconfres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_pathconfres *resp = rqstp->rq_resp;

        *p++ = xdr_zero;        /* no post_op_attr */

        if (resp->status == 0) {
                *p++ = htonl(resp->p_link_max);
                *p++ = htonl(resp->p_name_max);
                *p++ = htonl(resp->p_no_trunc);
                *p++ = htonl(resp->p_chown_restricted);
                *p++ = htonl(resp->p_case_insensitive);
                *p++ = htonl(resp->p_case_preserving);
        }

        return xdr_ressize_check(rqstp, p);
}

/* COMMIT */
int
nfs3svc_encode_commitres(struct svc_rqst *rqstp, __be32 *p)
{
        struct nfsd3_commitres *resp = rqstp->rq_resp;

        p = encode_wcc_data(rqstp, p, &resp->fh);
        /* Write verifier */
        if (resp->status == 0) {
                *p++ = resp->verf[0];
                *p++ = resp->verf[1];
        }
        return xdr_ressize_check(rqstp, p);
}

/*
 * XDR release functions
 */
void
nfs3svc_release_fhandle(struct svc_rqst *rqstp)
{
        struct nfsd3_attrstat *resp = rqstp->rq_resp;

        fh_put(&resp->fh);
}

void
nfs3svc_release_fhandle2(struct svc_rqst *rqstp)
{
        struct nfsd3_fhandle_pair *resp = rqstp->rq_resp;

        fh_put(&resp->fh1);
        fh_put(&resp->fh2);
}