// SPDX-License-Identifier: GPL-2.0
/*
 * This file contains all the stubs needed when communicating with lockd.
 * This level of indirection is necessary so we can run nfsd+lockd without
 * requiring the nfs client to be compiled in/loaded, and vice versa.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/file.h>
#include <linux/lockd/bind.h>
#include "nfsd.h"
#include "vfs.h"

#define NFSDDBG_FACILITY                NFSDDBG_LOCKD

/**
 * nlm_fopen - Open an NFSD file
 * @rqstp: NLM RPC procedure execution context
 * @f: NFS file handle to be opened
 * @filp: OUT: an opened struct file
 * @flags: the POSIX open flags to use
 *
 * nlm_fopen() holds the dentry reference until nlm_fclose() releases it.
 *
 * Returns zero on success or a negative errno value if the file
 * cannot be opened.
 */
static int nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f,
                     struct file **filp, int flags)
{
        __be32          nfserr;
        int             access;
        struct svc_fh   fh;

        /* must initialize before using! but maxsize doesn't matter */
        fh_init(&fh,0);
        fh.fh_handle.fh_size = f->size;
        memcpy(&fh.fh_handle.fh_raw, f->data, f->size);
        fh.fh_export = NULL;

        /*
         * Allow BYPASS_GSS as some client implementations use AUTH_SYS
         * for NLM even when GSS is used for NFS.
         * Allow OWNER_OVERRIDE as permission might have been changed
         * after the file was opened.
         * Pass MAY_NLM so that authentication can be completely bypassed
         * if NFSEXP_NOAUTHNLM is set.  Some older clients use AUTH_NULL
         * for NLM requests.
         */
        access = (flags == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
        access |= NFSD_MAY_NLM | NFSD_MAY_OWNER_OVERRIDE | NFSD_MAY_BYPASS_GSS;
        nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
        fh_put(&fh);

        switch (nfserr) {
        case nfs_ok:
                break;
        case nfserr_jukebox:
                /*
                 * This error can indicate a presence of a conflicting
                 * delegation to an NLM lock request. Options are:
                 * (1) For now, drop this request and make the client
                 * retry. When delegation is returned, client's lock retry
                 * will complete.
                 * (2) NLM4_DENIED as per "spec" signals to the client
                 * that the lock is unavailable now but client can retry.
                 * Linux client implementation does not. It treats
                 * NLM4_DENIED same as NLM4_FAILED and fails the request.
                 * (3) For the future, treat this as blocked lock and try
                 * to callback when the delegation is returned but might
                 * not have a proper lock request to block on.
                 */
                return -EWOULDBLOCK;
        case nfserr_stale:
                return -ESTALE;
        default:
                return -ENOLCK;
        }

        return 0;
}

/**
 * nlm_fclose - Close an NFSD file
 * @filp: a struct file that was opened by nlm_fopen()
 */
static void
nlm_fclose(struct file *filp)
{
        fput(filp);
}

static const struct nlmsvc_binding nfsd_nlm_ops = {
        .fopen          = nlm_fopen,            /* open file for locking */
        .fclose         = nlm_fclose,           /* close file */
};

void
nfsd_lockd_init(void)
{
        dprintk("nfsd: initializing lockd\n");
        nlmsvc_ops = &nfsd_nlm_ops;
}

void
nfsd_lockd_shutdown(void)
{
        nlmsvc_ops = NULL;
}