nfs3xdr.c

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/*
 * XDR support for nfsd/protocol version 3.
 *
 * Copyright (C) 1995, 1996, 1997 Olaf Kirch <[email protected]>
 *
 * 2003-08-09 Jamie Lokier: Use htonl() for nanoseconds, not htons()!
 */

#include <linux/namei.h>
#include "xdr3.h"
#include "auth.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 timespec *time)
{
    *p++ = htonl((u32) time->tv_sec); *p++ = htonl(time->tv_nsec);
    return p;
}

static __be32 *
decode_time3(__be32 *p, struct timespec *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)
{
    u32 tmp;

    iap->ia_valid = 0;

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

        iap->ia_valid |= ATTR_SIZE;
        p = xdr_decode_hyper(p, &newsize);
        if (newsize <= NFS_OFFSET_MAX)
            iap->ia_size = newsize;
        else
            iap->ia_size = 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_inode->i_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)
{
    *p++ = htonl(nfs3_ftypes[(stat->mode & S_IFMT) >> 12]);
    *p++ = htonl((u32) stat->mode);
    *p++ = htonl((u32) stat->nlink);
    *p++ = htonl((u32) nfsd_ruid(rqstp, stat->uid));
    *p++ = htonl((u32) nfsd_rgid(rqstp, 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 && dentry->d_inode) {
            int err;
        struct kstat stat;

        err = vfs_getattr(fhp->fh_export->ex_path.mnt, dentry, &stat);
        if (!err) {
            *p++ = xdr_one;     /* attributes follow */
            lease_get_mtime(dentry->d_inode, &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 && dentry->d_inode && 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 post_op attr for the wcc data
 */
void fill_post_wcc(struct svc_fh *fhp)
{
    int err;

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

    err = vfs_getattr(fhp->fh_export->ex_path.mnt, fhp->fh_dentry,
            &fhp->fh_post_attr);
    fhp->fh_post_change = fhp->fh_dentry->d_inode->i_version;
    if (err) {
        fhp->fh_post_saved = 0;
        /* Grab the ctime anyway - set_change_info might use it */
        fhp->fh_post_attr.ctime = fhp->fh_dentry->d_inode->i_ctime;
    } else
        fhp->fh_post_saved = 1;
}

/*
 * XDR decode functions
 */
int
nfs3svc_decode_fhandle(struct svc_rqst *rqstp, __be32 *p, struct nfsd_fhandle *args)
{
    if (!(p = decode_fh(p, &args->fh)))
        return 0;
    return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_sattrargs(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_sattrargs *args)
{
    if (!(p = decode_fh(p, &args->fh)))
        return 0;
    p = decode_sattr3(p, &args->attrs);

    if ((args->check_guard = ntohl(*p++)) != 0) { 
        struct timespec 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)
{
    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)
{
    if (!(p = decode_fh(p, &args->fh)))
        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)
{
    unsigned int len;
    int v,pn;
    u32 max_blocksize = svc_max_payload(rqstp);

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

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

    if (len > max_blocksize)
        len = max_blocksize;

    /* set up the kvec */
    v=0;
    while (len > 0) {
        pn = rqstp->rq_resused++;
        rqstp->rq_vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
        rqstp->rq_vec[v].iov_len = len < PAGE_SIZE? 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)
{
    unsigned int len, v, hdr, dlen;
    u32 max_blocksize = svc_max_payload(rqstp);

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

    args->count = ntohl(*p++);
    args->stable = ntohl(*p++);
    len = args->len = ntohl(*p++);
    /*
     * 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 - rqstp->rq_arg.head[0].iov_base;
    dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_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;
    }
    rqstp->rq_vec[0].iov_base = (void*)p;
    rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
    v = 0;
    while (len > rqstp->rq_vec[v].iov_len) {
        len -= rqstp->rq_vec[v].iov_len;
        v++;
        rqstp->rq_vec[v].iov_base = page_address(rqstp->rq_pages[v]);
        rqstp->rq_vec[v].iov_len = PAGE_SIZE;
    }
    rqstp->rq_vec[v].iov_len = len;
    args->vlen = v + 1;
    return 1;
}

int
nfs3svc_decode_createargs(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_createargs *args)
{
    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);
        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)
{
    if (!(p = decode_fh(p, &args->fh)) ||
        !(p = decode_filename(p, &args->name, &args->len)))
        return 0;
    p = decode_sattr3(p, &args->attrs);

    return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_symlinkargs *args)
{
    unsigned int len, avail;
    char *old, *new;
    struct kvec *vec;

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

    /* now decode the pathname, which might be larger than the first page.
     * As we have to check for nul's anyway, we copy it into a new page
     * This page appears in the rq_res.pages list, but as pages_len is always
     * 0, it won't get in the way
     */
    len = ntohl(*p++);
    if (len == 0 || len > NFS3_MAXPATHLEN || len >= PAGE_SIZE)
        return 0;
    args->tname = new =
        page_address(rqstp->rq_respages[rqstp->rq_resused++]);
    args->tlen = len;
    /* first copy and check from the first page */
    old = (char*)p;
    vec = &rqstp->rq_arg.head[0];
    avail = vec->iov_len - (old - (char*)vec->iov_base);
    while (len && avail && *old) {
        *new++ = *old++;
        len--;
        avail--;
    }
    /* now copy next page if there is one */
    if (len && !avail && rqstp->rq_arg.page_len) {
        avail = rqstp->rq_arg.page_len;
        if (avail > PAGE_SIZE)
            avail = PAGE_SIZE;
        old = page_address(rqstp->rq_arg.pages[0]);
    }
    while (len && avail && *old) {
        *new++ = *old++;
        len--;
        avail--;
    }
    *new = '\0';
    if (len)
        return 0;

    return 1;
}

int
nfs3svc_decode_mknodargs(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_mknodargs *args)
{
    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);

    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)
{
    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)
{
    if (!(p = decode_fh(p, &args->fh)))
        return 0;
    args->buffer =
        page_address(rqstp->rq_respages[rqstp->rq_resused++]);

    return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_linkargs(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_linkargs *args)
{
    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)
{
    if (!(p = decode_fh(p, &args->fh)))
        return 0;
    p = xdr_decode_hyper(p, &args->cookie);
    args->verf   = p; p += 2;
    args->dircount = ~0;
    args->count  = ntohl(*p++);

    if (args->count > PAGE_SIZE)
        args->count = PAGE_SIZE;

    args->buffer =
        page_address(rqstp->rq_respages[rqstp->rq_resused++]);

    return xdr_argsize_check(rqstp, p);
}

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

    if (!(p = decode_fh(p, &args->fh)))
        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 > max_blocksize) ? max_blocksize :
                          args->count;
    args->count = len;

    while (len > 0) {
        pn = rqstp->rq_resused++;
        if (!args->buffer)
            args->buffer = page_address(rqstp->rq_respages[pn]);
        len -= PAGE_SIZE;
    }

    return xdr_argsize_check(rqstp, p);
}

int
nfs3svc_decode_commitargs(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_commitargs *args)
{
    if (!(p = decode_fh(p, &args->fh)))
        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, void *dummy)
{
    return xdr_ressize_check(rqstp, p);
}

/* GETATTR */
int
nfs3svc_encode_attrstat(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_attrstat *resp)
{
    if (resp->status == 0) {
        lease_get_mtime(resp->fh.fh_dentry->d_inode,
                &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)
{
    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)
{
    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)
{
    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)
{
    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)
{
    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)
{
    p = encode_wcc_data(rqstp, p, &resp->fh);
    if (resp->status == 0) {
        *p++ = htonl(resp->count);
        *p++ = htonl(resp->committed);
        *p++ = htonl(nfssvc_boot.tv_sec);
        *p++ = htonl(nfssvc_boot.tv_usec);
    }
    return xdr_ressize_check(rqstp, p);
}

/* CREATE, MKDIR, SYMLINK, MKNOD */
int
nfs3svc_encode_createres(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_diropres *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)
{
    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)
{
    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)
{
    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)
{
    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_one_len(name, dparent, namlen);
    if (IS_ERR(dchild))
        return rv;
    if (d_mountpoint(dchild))
        goto out;
    if (!dchild->d_inode)
        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)
{
    struct svc_fh   fh;
    __be32 err;

    fh_init(&fh, NFS3_FHSIZE);
    err = compose_entry_fh(cd, &fh, name, namlen);
    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;
    int     pn;     /* current page number */
    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);
        }
    }

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

    /* truncate filename if too long */
    if (namlen > NFS3_MAXNAMLEN)
        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 (pn=1; pn < cd->rqstp->rq_resused; pn++) {
        curr_page_addr = page_address(cd->rqstp->rq_respages[pn]);

        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);
        num_entry_words = p - cd->buffer;
    } else if (cd->rqstp->rq_respages[pn+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(cd->rqstp->rq_respages[pn+1]);

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

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

        /* 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)
{
    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)
{
    *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)
{
    *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)
{
    p = encode_wcc_data(rqstp, p, &resp->fh);
    /* Write verifier */
    if (resp->status == 0) {
        *p++ = htonl(nfssvc_boot.tv_sec);
        *p++ = htonl(nfssvc_boot.tv_usec);
    }
    return xdr_ressize_check(rqstp, p);
}

/*
 * XDR release functions
 */
int
nfs3svc_release_fhandle(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_attrstat *resp)
{
    fh_put(&resp->fh);
    return 1;
}

int
nfs3svc_release_fhandle2(struct svc_rqst *rqstp, __be32 *p,
                    struct nfsd3_fhandle_pair *resp)
{
    fh_put(&resp->fh1);
    fh_put(&resp->fh2);
    return 1;
}