client.c

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/* client.c: NFS client sharing and management code
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */


#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/metrics.h>
#include <linux/sunrpc/xprtsock.h>
#include <linux/sunrpc/xprtrdma.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/lockd/bind.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/inet.h>
#include <linux/in6.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <net/ipv6.h>
#include <linux/nfs_xdr.h>
#include <linux/sunrpc/bc_xprt.h>
#include <linux/nsproxy.h>
#include <linux/pid_namespace.h>


#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"
#include "pnfs.h"
#include "nfs.h"
#include "netns.h"

#define NFSDBG_FACILITY     NFSDBG_CLIENT

static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);
static DEFINE_SPINLOCK(nfs_version_lock);
static DEFINE_MUTEX(nfs_version_mutex);
static LIST_HEAD(nfs_versions);

/*
 * RPC cruft for NFS
 */
static const struct rpc_version *nfs_version[5] = {
    [2] = NULL,
    [3] = NULL,
    [4] = NULL,
};

const struct rpc_program nfs_program = {
    .name           = "nfs",
    .number         = NFS_PROGRAM,
    .nrvers         = ARRAY_SIZE(nfs_version),
    .version        = nfs_version,
    .stats          = &nfs_rpcstat,
    .pipe_dir_name      = NFS_PIPE_DIRNAME,
};

struct rpc_stat nfs_rpcstat = {
    .program        = &nfs_program
};

static struct nfs_subversion *find_nfs_version(unsigned int version)
{
    struct nfs_subversion *nfs;
    spin_lock(&nfs_version_lock);

    list_for_each_entry(nfs, &nfs_versions, list) {
        if (nfs->rpc_ops->version == version) {
            spin_unlock(&nfs_version_lock);
            return nfs;
        }
    }

    spin_unlock(&nfs_version_lock);
    return ERR_PTR(-EPROTONOSUPPORT);
}

struct nfs_subversion *get_nfs_version(unsigned int version)
{
    struct nfs_subversion *nfs = find_nfs_version(version);

    if (IS_ERR(nfs)) {
        mutex_lock(&nfs_version_mutex);
        request_module("nfsv%d", version);
        nfs = find_nfs_version(version);
        mutex_unlock(&nfs_version_mutex);
    }

    if (!IS_ERR(nfs))
        try_module_get(nfs->owner);
    return nfs;
}

void put_nfs_version(struct nfs_subversion *nfs)
{
    module_put(nfs->owner);
}

void register_nfs_version(struct nfs_subversion *nfs)
{
    spin_lock(&nfs_version_lock);

    list_add(&nfs->list, &nfs_versions);
    nfs_version[nfs->rpc_ops->version] = nfs->rpc_vers;

    spin_unlock(&nfs_version_lock);
}
EXPORT_SYMBOL_GPL(register_nfs_version);

void unregister_nfs_version(struct nfs_subversion *nfs)
{
    spin_lock(&nfs_version_lock);

    nfs_version[nfs->rpc_ops->version] = NULL;
    list_del(&nfs->list);

    spin_unlock(&nfs_version_lock);
}
EXPORT_SYMBOL_GPL(unregister_nfs_version);

/*
 * Allocate a shared client record
 *
 * Since these are allocated/deallocated very rarely, we don't
 * bother putting them in a slab cache...
 */
struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
{
    struct nfs_client *clp;
    struct rpc_cred *cred;
    int err = -ENOMEM;

    if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
        goto error_0;

    clp->cl_nfs_mod = cl_init->nfs_mod;
    try_module_get(clp->cl_nfs_mod->owner);

    clp->rpc_ops = clp->cl_nfs_mod->rpc_ops;

    atomic_set(&clp->cl_count, 1);
    clp->cl_cons_state = NFS_CS_INITING;

    memcpy(&clp->cl_addr, cl_init->addr, cl_init->addrlen);
    clp->cl_addrlen = cl_init->addrlen;

    if (cl_init->hostname) {
        err = -ENOMEM;
        clp->cl_hostname = kstrdup(cl_init->hostname, GFP_KERNEL);
        if (!clp->cl_hostname)
            goto error_cleanup;
    }

    INIT_LIST_HEAD(&clp->cl_superblocks);
    clp->cl_rpcclient = ERR_PTR(-EINVAL);

    clp->cl_proto = cl_init->proto;
    clp->cl_net = get_net(cl_init->net);

    cred = rpc_lookup_machine_cred("*");
    if (!IS_ERR(cred))
        clp->cl_machine_cred = cred;
    nfs_fscache_get_client_cookie(clp);

    return clp;

error_cleanup:
    put_nfs_version(clp->cl_nfs_mod);
    kfree(clp);
error_0:
    return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(nfs_alloc_client);

#if IS_ENABLED(CONFIG_NFS_V4)
/* idr_remove_all is not needed as all id's are removed by nfs_put_client */
void nfs_cleanup_cb_ident_idr(struct net *net)
{
    struct nfs_net *nn = net_generic(net, nfs_net_id);

    idr_destroy(&nn->cb_ident_idr);
}

/* nfs_client_lock held */
static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
{
    struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);

    if (clp->cl_cb_ident)
        idr_remove(&nn->cb_ident_idr, clp->cl_cb_ident);
}

static void pnfs_init_server(struct nfs_server *server)
{
    rpc_init_wait_queue(&server->roc_rpcwaitq, "pNFS ROC");
}

#else
void nfs_cleanup_cb_ident_idr(struct net *net)
{
}

static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
{
}

static void pnfs_init_server(struct nfs_server *server)
{
}

#endif /* CONFIG_NFS_V4 */

/*
 * Destroy a shared client record
 */
void nfs_free_client(struct nfs_client *clp)
{
    dprintk("--> nfs_free_client(%u)\n", clp->rpc_ops->version);

    nfs_fscache_release_client_cookie(clp);

    /* -EIO all pending I/O */
    if (!IS_ERR(clp->cl_rpcclient))
        rpc_shutdown_client(clp->cl_rpcclient);

    if (clp->cl_machine_cred != NULL)
        put_rpccred(clp->cl_machine_cred);

    put_net(clp->cl_net);
    put_nfs_version(clp->cl_nfs_mod);
    kfree(clp->cl_hostname);
    kfree(clp);

    dprintk("<-- nfs_free_client()\n");
}
EXPORT_SYMBOL_GPL(nfs_free_client);

/*
 * Release a reference to a shared client record
 */
void nfs_put_client(struct nfs_client *clp)
{
    struct nfs_net *nn;

    if (!clp)
        return;

    dprintk("--> nfs_put_client({%d})\n", atomic_read(&clp->cl_count));
    nn = net_generic(clp->cl_net, nfs_net_id);

    if (atomic_dec_and_lock(&clp->cl_count, &nn->nfs_client_lock)) {
        list_del(&clp->cl_share_link);
        nfs_cb_idr_remove_locked(clp);
        spin_unlock(&nn->nfs_client_lock);

        BUG_ON(!list_empty(&clp->cl_superblocks));

        clp->rpc_ops->free_client(clp);
    }
}
EXPORT_SYMBOL_GPL(nfs_put_client);

#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
/*
 * Test if two ip6 socket addresses refer to the same socket by
 * comparing relevant fields. The padding bytes specifically, are not
 * compared. sin6_flowinfo is not compared because it only affects QoS
 * and sin6_scope_id is only compared if the address is "link local"
 * because "link local" addresses need only be unique to a specific
 * link. Conversely, ordinary unicast addresses might have different
 * sin6_scope_id.
 *
 * The caller should ensure both socket addresses are AF_INET6.
 */
static int nfs_sockaddr_match_ipaddr6(const struct sockaddr *sa1,
                      const struct sockaddr *sa2)
{
    const struct sockaddr_in6 *sin1 = (const struct sockaddr_in6 *)sa1;
    const struct sockaddr_in6 *sin2 = (const struct sockaddr_in6 *)sa2;

    if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
        return 0;
    else if (ipv6_addr_type(&sin1->sin6_addr) & IPV6_ADDR_LINKLOCAL)
        return sin1->sin6_scope_id == sin2->sin6_scope_id;

    return 1;
}
#else   /* !defined(CONFIG_IPV6) && !defined(CONFIG_IPV6_MODULE) */
static int nfs_sockaddr_match_ipaddr6(const struct sockaddr *sa1,
                      const struct sockaddr *sa2)
{
    return 0;
}
#endif

/*
 * Test if two ip4 socket addresses refer to the same socket, by
 * comparing relevant fields. The padding bytes specifically, are
 * not compared.
 *
 * The caller should ensure both socket addresses are AF_INET.
 */
static int nfs_sockaddr_match_ipaddr4(const struct sockaddr *sa1,
                      const struct sockaddr *sa2)
{
    const struct sockaddr_in *sin1 = (const struct sockaddr_in *)sa1;
    const struct sockaddr_in *sin2 = (const struct sockaddr_in *)sa2;

    return sin1->sin_addr.s_addr == sin2->sin_addr.s_addr;
}

static int nfs_sockaddr_cmp_ip6(const struct sockaddr *sa1,
                const struct sockaddr *sa2)
{
    const struct sockaddr_in6 *sin1 = (const struct sockaddr_in6 *)sa1;
    const struct sockaddr_in6 *sin2 = (const struct sockaddr_in6 *)sa2;

    return nfs_sockaddr_match_ipaddr6(sa1, sa2) &&
        (sin1->sin6_port == sin2->sin6_port);
}

static int nfs_sockaddr_cmp_ip4(const struct sockaddr *sa1,
                const struct sockaddr *sa2)
{
    const struct sockaddr_in *sin1 = (const struct sockaddr_in *)sa1;
    const struct sockaddr_in *sin2 = (const struct sockaddr_in *)sa2;

    return nfs_sockaddr_match_ipaddr4(sa1, sa2) &&
        (sin1->sin_port == sin2->sin_port);
}

#if defined(CONFIG_NFS_V4_1)
/*
 * Test if two socket addresses represent the same actual socket,
 * by comparing (only) relevant fields, excluding the port number.
 */
int nfs_sockaddr_match_ipaddr(const struct sockaddr *sa1,
                  const struct sockaddr *sa2)
{
    if (sa1->sa_family != sa2->sa_family)
        return 0;

    switch (sa1->sa_family) {
    case AF_INET:
        return nfs_sockaddr_match_ipaddr4(sa1, sa2);
    case AF_INET6:
        return nfs_sockaddr_match_ipaddr6(sa1, sa2);
    }
    return 0;
}
EXPORT_SYMBOL_GPL(nfs_sockaddr_match_ipaddr);
#endif /* CONFIG_NFS_V4_1 */

/*
 * Test if two socket addresses represent the same actual socket,
 * by comparing (only) relevant fields, including the port number.
 */
static int nfs_sockaddr_cmp(const struct sockaddr *sa1,
                const struct sockaddr *sa2)
{
    if (sa1->sa_family != sa2->sa_family)
        return 0;

    switch (sa1->sa_family) {
    case AF_INET:
        return nfs_sockaddr_cmp_ip4(sa1, sa2);
    case AF_INET6:
        return nfs_sockaddr_cmp_ip6(sa1, sa2);
    }
    return 0;
}

/*
 * Find an nfs_client on the list that matches the initialisation data
 * that is supplied.
 */
static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *data)
{
    struct nfs_client *clp;
    const struct sockaddr *sap = data->addr;
    struct nfs_net *nn = net_generic(data->net, nfs_net_id);

    list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
            const struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
        /* Don't match clients that failed to initialise properly */
        if (clp->cl_cons_state < 0)
            continue;

        /* Different NFS versions cannot share the same nfs_client */
        if (clp->rpc_ops != data->nfs_mod->rpc_ops)
            continue;

        if (clp->cl_proto != data->proto)
            continue;
        /* Match nfsv4 minorversion */
        if (clp->cl_minorversion != data->minorversion)
            continue;
        /* Match the full socket address */
        if (!nfs_sockaddr_cmp(sap, clap))
            continue;

        atomic_inc(&clp->cl_count);
        return clp;
    }
    return NULL;
}

static bool nfs_client_init_is_complete(const struct nfs_client *clp)
{
    return clp->cl_cons_state != NFS_CS_INITING;
}

int nfs_wait_client_init_complete(const struct nfs_client *clp)
{
    return wait_event_killable(nfs_client_active_wq,
            nfs_client_init_is_complete(clp));
}
EXPORT_SYMBOL_GPL(nfs_wait_client_init_complete);

/*
 * Found an existing client.  Make sure it's ready before returning.
 */
static struct nfs_client *
nfs_found_client(const struct nfs_client_initdata *cl_init,
         struct nfs_client *clp)
{
    int error;

    error = nfs_wait_client_init_complete(clp);
    if (error < 0) {
        nfs_put_client(clp);
        return ERR_PTR(-ERESTARTSYS);
    }

    if (clp->cl_cons_state < NFS_CS_READY) {
        error = clp->cl_cons_state;
        nfs_put_client(clp);
        return ERR_PTR(error);
    }

    smp_rmb();

    dprintk("<-- %s found nfs_client %p for %s\n",
        __func__, clp, cl_init->hostname ?: "");
    return clp;
}

/*
 * Look up a client by IP address and protocol version
 * - creates a new record if one doesn't yet exist
 */
struct nfs_client *
nfs_get_client(const struct nfs_client_initdata *cl_init,
           const struct rpc_timeout *timeparms,
           const char *ip_addr,
           rpc_authflavor_t authflavour)
{
    struct nfs_client *clp, *new = NULL;
    struct nfs_net *nn = net_generic(cl_init->net, nfs_net_id);
    const struct nfs_rpc_ops *rpc_ops = cl_init->nfs_mod->rpc_ops;

    dprintk("--> nfs_get_client(%s,v%u)\n",
        cl_init->hostname ?: "", rpc_ops->version);

    /* see if the client already exists */
    do {
        spin_lock(&nn->nfs_client_lock);

        clp = nfs_match_client(cl_init);
        if (clp) {
            spin_unlock(&nn->nfs_client_lock);
            if (new)
                new->rpc_ops->free_client(new);
            return nfs_found_client(cl_init, clp);
        }
        if (new) {
            list_add_tail(&new->cl_share_link,
                    &nn->nfs_client_list);
            spin_unlock(&nn->nfs_client_lock);
            new->cl_flags = cl_init->init_flags;
            return rpc_ops->init_client(new, timeparms, ip_addr,
                            authflavour);
        }

        spin_unlock(&nn->nfs_client_lock);

        new = rpc_ops->alloc_client(cl_init);
    } while (!IS_ERR(new));

    dprintk("<-- nfs_get_client() Failed to find %s (%ld)\n",
        cl_init->hostname ?: "", PTR_ERR(new));
    return new;
}
EXPORT_SYMBOL_GPL(nfs_get_client);

/*
 * Mark a server as ready or failed
 */
void nfs_mark_client_ready(struct nfs_client *clp, int state)
{
    smp_wmb();
    clp->cl_cons_state = state;
    wake_up_all(&nfs_client_active_wq);
}
EXPORT_SYMBOL_GPL(nfs_mark_client_ready);

/*
 * Initialise the timeout values for a connection
 */
void nfs_init_timeout_values(struct rpc_timeout *to, int proto,
                    unsigned int timeo, unsigned int retrans)
{
    to->to_initval = timeo * HZ / 10;
    to->to_retries = retrans;

    switch (proto) {
    case XPRT_TRANSPORT_TCP:
    case XPRT_TRANSPORT_RDMA:
        if (to->to_retries == 0)
            to->to_retries = NFS_DEF_TCP_RETRANS;
        if (to->to_initval == 0)
            to->to_initval = NFS_DEF_TCP_TIMEO * HZ / 10;
        if (to->to_initval > NFS_MAX_TCP_TIMEOUT)
            to->to_initval = NFS_MAX_TCP_TIMEOUT;
        to->to_increment = to->to_initval;
        to->to_maxval = to->to_initval + (to->to_increment * to->to_retries);
        if (to->to_maxval > NFS_MAX_TCP_TIMEOUT)
            to->to_maxval = NFS_MAX_TCP_TIMEOUT;
        if (to->to_maxval < to->to_initval)
            to->to_maxval = to->to_initval;
        to->to_exponential = 0;
        break;
    case XPRT_TRANSPORT_UDP:
        if (to->to_retries == 0)
            to->to_retries = NFS_DEF_UDP_RETRANS;
        if (!to->to_initval)
            to->to_initval = NFS_DEF_UDP_TIMEO * HZ / 10;
        if (to->to_initval > NFS_MAX_UDP_TIMEOUT)
            to->to_initval = NFS_MAX_UDP_TIMEOUT;
        to->to_maxval = NFS_MAX_UDP_TIMEOUT;
        to->to_exponential = 1;
        break;
    default:
        BUG();
    }
}
EXPORT_SYMBOL_GPL(nfs_init_timeout_values);

/*
 * Create an RPC client handle
 */
int nfs_create_rpc_client(struct nfs_client *clp,
              const struct rpc_timeout *timeparms,
              rpc_authflavor_t flavor)
{
    struct rpc_clnt     *clnt = NULL;
    struct rpc_create_args args = {
        .net        = clp->cl_net,
        .protocol   = clp->cl_proto,
        .address    = (struct sockaddr *)&clp->cl_addr,
        .addrsize   = clp->cl_addrlen,
        .timeout    = timeparms,
        .servername = clp->cl_hostname,
        .program    = &nfs_program,
        .version    = clp->rpc_ops->version,
        .authflavor = flavor,
    };

    if (test_bit(NFS_CS_DISCRTRY, &clp->cl_flags))
        args.flags |= RPC_CLNT_CREATE_DISCRTRY;
    if (test_bit(NFS_CS_NORESVPORT, &clp->cl_flags))
        args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;

    if (!IS_ERR(clp->cl_rpcclient))
        return 0;

    clnt = rpc_create(&args);
    if (IS_ERR(clnt)) {
        dprintk("%s: cannot create RPC client. Error = %ld\n",
                __func__, PTR_ERR(clnt));
        return PTR_ERR(clnt);
    }

    clp->cl_rpcclient = clnt;
    return 0;
}
EXPORT_SYMBOL_GPL(nfs_create_rpc_client);

/*
 * Version 2 or 3 client destruction
 */
static void nfs_destroy_server(struct nfs_server *server)
{
    if (!(server->flags & NFS_MOUNT_LOCAL_FLOCK) ||
            !(server->flags & NFS_MOUNT_LOCAL_FCNTL))
        nlmclnt_done(server->nlm_host);
}

/*
 * Version 2 or 3 lockd setup
 */
static int nfs_start_lockd(struct nfs_server *server)
{
    struct nlm_host *host;
    struct nfs_client *clp = server->nfs_client;
    struct nlmclnt_initdata nlm_init = {
        .hostname   = clp->cl_hostname,
        .address    = (struct sockaddr *)&clp->cl_addr,
        .addrlen    = clp->cl_addrlen,
        .nfs_version    = clp->rpc_ops->version,
        .noresvport = server->flags & NFS_MOUNT_NORESVPORT ?
                    1 : 0,
        .net        = clp->cl_net,
    };

    if (nlm_init.nfs_version > 3)
        return 0;
    if ((server->flags & NFS_MOUNT_LOCAL_FLOCK) &&
            (server->flags & NFS_MOUNT_LOCAL_FCNTL))
        return 0;

    switch (clp->cl_proto) {
        default:
            nlm_init.protocol = IPPROTO_TCP;
            break;
        case XPRT_TRANSPORT_UDP:
            nlm_init.protocol = IPPROTO_UDP;
    }

    host = nlmclnt_init(&nlm_init);
    if (IS_ERR(host))
        return PTR_ERR(host);

    server->nlm_host = host;
    server->destroy = nfs_destroy_server;
    return 0;
}

/*
 * Create a general RPC client
 */
int nfs_init_server_rpcclient(struct nfs_server *server,
        const struct rpc_timeout *timeo,
        rpc_authflavor_t pseudoflavour)
{
    struct nfs_client *clp = server->nfs_client;

    server->client = rpc_clone_client_set_auth(clp->cl_rpcclient,
                            pseudoflavour);
    if (IS_ERR(server->client)) {
        dprintk("%s: couldn't create rpc_client!\n", __func__);
        return PTR_ERR(server->client);
    }

    memcpy(&server->client->cl_timeout_default,
            timeo,
            sizeof(server->client->cl_timeout_default));
    server->client->cl_timeout = &server->client->cl_timeout_default;
    server->client->cl_softrtry = 0;
    if (server->flags & NFS_MOUNT_SOFT)
        server->client->cl_softrtry = 1;

    return 0;
}
EXPORT_SYMBOL_GPL(nfs_init_server_rpcclient);

struct nfs_client *nfs_init_client(struct nfs_client *clp,
            const struct rpc_timeout *timeparms,
            const char *ip_addr, rpc_authflavor_t authflavour)
{
    int error;

    if (clp->cl_cons_state == NFS_CS_READY) {
        /* the client is already initialised */
        dprintk("<-- nfs_init_client() = 0 [already %p]\n", clp);
        return clp;
    }

    /*
     * Create a client RPC handle for doing FSSTAT with UNIX auth only
     * - RFC 2623, sec 2.3.2
     */
    error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_UNIX);
    if (error < 0)
        goto error;
    nfs_mark_client_ready(clp, NFS_CS_READY);
    return clp;

error:
    nfs_mark_client_ready(clp, error);
    nfs_put_client(clp);
    dprintk("<-- nfs_init_client() = xerror %d\n", error);
    return ERR_PTR(error);
}
EXPORT_SYMBOL_GPL(nfs_init_client);

/*
 * Create a version 2 or 3 client
 */
static int nfs_init_server(struct nfs_server *server,
               const struct nfs_parsed_mount_data *data,
               struct nfs_subversion *nfs_mod)
{
    struct nfs_client_initdata cl_init = {
        .hostname = data->nfs_server.hostname,
        .addr = (const struct sockaddr *)&data->nfs_server.address,
        .addrlen = data->nfs_server.addrlen,
        .nfs_mod = nfs_mod,
        .proto = data->nfs_server.protocol,
        .net = data->net,
    };
    struct rpc_timeout timeparms;
    struct nfs_client *clp;
    int error;

    dprintk("--> nfs_init_server()\n");

    nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
            data->timeo, data->retrans);
    if (data->flags & NFS_MOUNT_NORESVPORT)
        set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
    if (server->options & NFS_OPTION_MIGRATION)
        set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);

    /* Allocate or find a client reference we can use */
    clp = nfs_get_client(&cl_init, &timeparms, NULL, RPC_AUTH_UNIX);
    if (IS_ERR(clp)) {
        dprintk("<-- nfs_init_server() = error %ld\n", PTR_ERR(clp));
        return PTR_ERR(clp);
    }

    server->nfs_client = clp;

    /* Initialise the client representation from the mount data */
    server->flags = data->flags;
    server->options = data->options;
    server->caps |= NFS_CAP_HARDLINKS|NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
        NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|NFS_CAP_OWNER_GROUP|
        NFS_CAP_ATIME|NFS_CAP_CTIME|NFS_CAP_MTIME|NFS_CAP_CHANGE_ATTR;

    if (data->rsize)
        server->rsize = nfs_block_size(data->rsize, NULL);
    if (data->wsize)
        server->wsize = nfs_block_size(data->wsize, NULL);

    server->acregmin = data->acregmin * HZ;
    server->acregmax = data->acregmax * HZ;
    server->acdirmin = data->acdirmin * HZ;
    server->acdirmax = data->acdirmax * HZ;

    /* Start lockd here, before we might error out */
    error = nfs_start_lockd(server);
    if (error < 0)
        goto error;

    server->port = data->nfs_server.port;

    error = nfs_init_server_rpcclient(server, &timeparms, data->auth_flavors[0]);
    if (error < 0)
        goto error;

    /* Preserve the values of mount_server-related mount options */
    if (data->mount_server.addrlen) {
        memcpy(&server->mountd_address, &data->mount_server.address,
            data->mount_server.addrlen);
        server->mountd_addrlen = data->mount_server.addrlen;
    }
    server->mountd_version = data->mount_server.version;
    server->mountd_port = data->mount_server.port;
    server->mountd_protocol = data->mount_server.protocol;

    server->namelen  = data->namlen;
    dprintk("<-- nfs_init_server() = 0 [new %p]\n", clp);
    return 0;

error:
    server->nfs_client = NULL;
    nfs_put_client(clp);
    dprintk("<-- nfs_init_server() = xerror %d\n", error);
    return error;
}

/*
 * Load up the server record from information gained in an fsinfo record
 */
static void nfs_server_set_fsinfo(struct nfs_server *server,
                  struct nfs_fh *mntfh,
                  struct nfs_fsinfo *fsinfo)
{
    unsigned long max_rpc_payload;

    /* Work out a lot of parameters */
    if (server->rsize == 0)
        server->rsize = nfs_block_size(fsinfo->rtpref, NULL);
    if (server->wsize == 0)
        server->wsize = nfs_block_size(fsinfo->wtpref, NULL);

    if (fsinfo->rtmax >= 512 && server->rsize > fsinfo->rtmax)
        server->rsize = nfs_block_size(fsinfo->rtmax, NULL);
    if (fsinfo->wtmax >= 512 && server->wsize > fsinfo->wtmax)
        server->wsize = nfs_block_size(fsinfo->wtmax, NULL);

    max_rpc_payload = nfs_block_size(rpc_max_payload(server->client), NULL);
    if (server->rsize > max_rpc_payload)
        server->rsize = max_rpc_payload;
    if (server->rsize > NFS_MAX_FILE_IO_SIZE)
        server->rsize = NFS_MAX_FILE_IO_SIZE;
    server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

    server->backing_dev_info.name = "nfs";
    server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;

    if (server->wsize > max_rpc_payload)
        server->wsize = max_rpc_payload;
    if (server->wsize > NFS_MAX_FILE_IO_SIZE)
        server->wsize = NFS_MAX_FILE_IO_SIZE;
    server->wpages = (server->wsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

    server->wtmult = nfs_block_bits(fsinfo->wtmult, NULL);

    server->dtsize = nfs_block_size(fsinfo->dtpref, NULL);
    if (server->dtsize > PAGE_CACHE_SIZE * NFS_MAX_READDIR_PAGES)
        server->dtsize = PAGE_CACHE_SIZE * NFS_MAX_READDIR_PAGES;
    if (server->dtsize > server->rsize)
        server->dtsize = server->rsize;

    if (server->flags & NFS_MOUNT_NOAC) {
        server->acregmin = server->acregmax = 0;
        server->acdirmin = server->acdirmax = 0;
    }

    server->maxfilesize = fsinfo->maxfilesize;

    server->time_delta = fsinfo->time_delta;

    /* We're airborne Set socket buffersize */
    rpc_setbufsize(server->client, server->wsize + 100, server->rsize + 100);
}

/*
 * Probe filesystem information, including the FSID on v2/v3
 */
int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, struct nfs_fattr *fattr)
{
    struct nfs_fsinfo fsinfo;
    struct nfs_client *clp = server->nfs_client;
    int error;

    dprintk("--> nfs_probe_fsinfo()\n");

    if (clp->rpc_ops->set_capabilities != NULL) {
        error = clp->rpc_ops->set_capabilities(server, mntfh);
        if (error < 0)
            goto out_error;
    }

    fsinfo.fattr = fattr;
    fsinfo.layouttype = 0;
    error = clp->rpc_ops->fsinfo(server, mntfh, &fsinfo);
    if (error < 0)
        goto out_error;

    nfs_server_set_fsinfo(server, mntfh, &fsinfo);

    /* Get some general file system info */
    if (server->namelen == 0) {
        struct nfs_pathconf pathinfo;

        pathinfo.fattr = fattr;
        nfs_fattr_init(fattr);

        if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0)
            server->namelen = pathinfo.max_namelen;
    }

    dprintk("<-- nfs_probe_fsinfo() = 0\n");
    return 0;

out_error:
    dprintk("nfs_probe_fsinfo: error = %d\n", -error);
    return error;
}
EXPORT_SYMBOL_GPL(nfs_probe_fsinfo);

/*
 * Copy useful information when duplicating a server record
 */
void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *source)
{
    target->flags = source->flags;
    target->rsize = source->rsize;
    target->wsize = source->wsize;
    target->acregmin = source->acregmin;
    target->acregmax = source->acregmax;
    target->acdirmin = source->acdirmin;
    target->acdirmax = source->acdirmax;
    target->caps = source->caps;
    target->options = source->options;
}
EXPORT_SYMBOL_GPL(nfs_server_copy_userdata);

void nfs_server_insert_lists(struct nfs_server *server)
{
    struct nfs_client *clp = server->nfs_client;
    struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);

    spin_lock(&nn->nfs_client_lock);
    list_add_tail_rcu(&server->client_link, &clp->cl_superblocks);
    list_add_tail(&server->master_link, &nn->nfs_volume_list);
    clear_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state);
    spin_unlock(&nn->nfs_client_lock);

}
EXPORT_SYMBOL_GPL(nfs_server_insert_lists);

static void nfs_server_remove_lists(struct nfs_server *server)
{
    struct nfs_client *clp = server->nfs_client;
    struct nfs_net *nn;

    if (clp == NULL)
        return;
    nn = net_generic(clp->cl_net, nfs_net_id);
    spin_lock(&nn->nfs_client_lock);
    list_del_rcu(&server->client_link);
    if (list_empty(&clp->cl_superblocks))
        set_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state);
    list_del(&server->master_link);
    spin_unlock(&nn->nfs_client_lock);

    synchronize_rcu();
}

/*
 * Allocate and initialise a server record
 */
struct nfs_server *nfs_alloc_server(void)
{
    struct nfs_server *server;

    server = kzalloc(sizeof(struct nfs_server), GFP_KERNEL);
    if (!server)
        return NULL;

    server->client = server->client_acl = ERR_PTR(-EINVAL);

    /* Zero out the NFS state stuff */
    INIT_LIST_HEAD(&server->client_link);
    INIT_LIST_HEAD(&server->master_link);
    INIT_LIST_HEAD(&server->delegations);
    INIT_LIST_HEAD(&server->layouts);
    INIT_LIST_HEAD(&server->state_owners_lru);

    atomic_set(&server->active, 0);

    server->io_stats = nfs_alloc_iostats();
    if (!server->io_stats) {
        kfree(server);
        return NULL;
    }

    if (bdi_init(&server->backing_dev_info)) {
        nfs_free_iostats(server->io_stats);
        kfree(server);
        return NULL;
    }

    ida_init(&server->openowner_id);
    ida_init(&server->lockowner_id);
    pnfs_init_server(server);

    return server;
}
EXPORT_SYMBOL_GPL(nfs_alloc_server);

/*
 * Free up a server record
 */
void nfs_free_server(struct nfs_server *server)
{
    dprintk("--> nfs_free_server()\n");

    nfs_server_remove_lists(server);

    if (server->destroy != NULL)
        server->destroy(server);

    if (!IS_ERR(server->client_acl))
        rpc_shutdown_client(server->client_acl);
    if (!IS_ERR(server->client))
        rpc_shutdown_client(server->client);

    nfs_put_client(server->nfs_client);

    ida_destroy(&server->lockowner_id);
    ida_destroy(&server->openowner_id);
    nfs_free_iostats(server->io_stats);
    bdi_destroy(&server->backing_dev_info);
    kfree(server);
    nfs_release_automount_timer();
    dprintk("<-- nfs_free_server()\n");
}
EXPORT_SYMBOL_GPL(nfs_free_server);

/*
 * Create a version 2 or 3 volume record
 * - keyed on server and FSID
 */
struct nfs_server *nfs_create_server(struct nfs_mount_info *mount_info,
                     struct nfs_subversion *nfs_mod)
{
    struct nfs_server *server;
    struct nfs_fattr *fattr;
    int error;

    server = nfs_alloc_server();
    if (!server)
        return ERR_PTR(-ENOMEM);

    error = -ENOMEM;
    fattr = nfs_alloc_fattr();
    if (fattr == NULL)
        goto error;

    /* Get a client representation */
    error = nfs_init_server(server, mount_info->parsed, nfs_mod);
    if (error < 0)
        goto error;

    BUG_ON(!server->nfs_client);
    BUG_ON(!server->nfs_client->rpc_ops);
    BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

    /* Probe the root fh to retrieve its FSID */
    error = nfs_probe_fsinfo(server, mount_info->mntfh, fattr);
    if (error < 0)
        goto error;
    if (server->nfs_client->rpc_ops->version == 3) {
        if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
            server->namelen = NFS3_MAXNAMLEN;
        if (!(mount_info->parsed->flags & NFS_MOUNT_NORDIRPLUS))
            server->caps |= NFS_CAP_READDIRPLUS;
    } else {
        if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
            server->namelen = NFS2_MAXNAMLEN;
    }

    if (!(fattr->valid & NFS_ATTR_FATTR)) {
        error = nfs_mod->rpc_ops->getattr(server, mount_info->mntfh, fattr);
        if (error < 0) {
            dprintk("nfs_create_server: getattr error = %d\n", -error);
            goto error;
        }
    }
    memcpy(&server->fsid, &fattr->fsid, sizeof(server->fsid));

    dprintk("Server FSID: %llx:%llx\n",
        (unsigned long long) server->fsid.major,
        (unsigned long long) server->fsid.minor);

    nfs_server_insert_lists(server);
    server->mount_time = jiffies;
    nfs_free_fattr(fattr);
    return server;

error:
    nfs_free_fattr(fattr);
    nfs_free_server(server);
    return ERR_PTR(error);
}
EXPORT_SYMBOL_GPL(nfs_create_server);

/*
 * Clone an NFS2, NFS3 or NFS4 server record
 */
struct nfs_server *nfs_clone_server(struct nfs_server *source,
                    struct nfs_fh *fh,
                    struct nfs_fattr *fattr,
                    rpc_authflavor_t flavor)
{
    struct nfs_server *server;
    struct nfs_fattr *fattr_fsinfo;
    int error;

    dprintk("--> nfs_clone_server(,%llx:%llx,)\n",
        (unsigned long long) fattr->fsid.major,
        (unsigned long long) fattr->fsid.minor);

    server = nfs_alloc_server();
    if (!server)
        return ERR_PTR(-ENOMEM);

    error = -ENOMEM;
    fattr_fsinfo = nfs_alloc_fattr();
    if (fattr_fsinfo == NULL)
        goto out_free_server;

    /* Copy data from the source */
    server->nfs_client = source->nfs_client;
    server->destroy = source->destroy;
    atomic_inc(&server->nfs_client->cl_count);
    nfs_server_copy_userdata(server, source);

    server->fsid = fattr->fsid;

    error = nfs_init_server_rpcclient(server,
            source->client->cl_timeout,
            flavor);
    if (error < 0)
        goto out_free_server;

    /* probe the filesystem info for this server filesystem */
    error = nfs_probe_fsinfo(server, fh, fattr_fsinfo);
    if (error < 0)
        goto out_free_server;

    if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
        server->namelen = NFS4_MAXNAMLEN;

    dprintk("Cloned FSID: %llx:%llx\n",
        (unsigned long long) server->fsid.major,
        (unsigned long long) server->fsid.minor);

    error = nfs_start_lockd(server);
    if (error < 0)
        goto out_free_server;

    nfs_server_insert_lists(server);
    server->mount_time = jiffies;

    nfs_free_fattr(fattr_fsinfo);
    dprintk("<-- nfs_clone_server() = %p\n", server);
    return server;

out_free_server:
    nfs_free_fattr(fattr_fsinfo);
    nfs_free_server(server);
    dprintk("<-- nfs_clone_server() = error %d\n", error);
    return ERR_PTR(error);
}
EXPORT_SYMBOL_GPL(nfs_clone_server);

void nfs_clients_init(struct net *net)
{
    struct nfs_net *nn = net_generic(net, nfs_net_id);

    INIT_LIST_HEAD(&nn->nfs_client_list);
    INIT_LIST_HEAD(&nn->nfs_volume_list);
#if IS_ENABLED(CONFIG_NFS_V4)
    idr_init(&nn->cb_ident_idr);
#endif
    spin_lock_init(&nn->nfs_client_lock);
    nn->boot_time = CURRENT_TIME;
}

#ifdef CONFIG_PROC_FS
static struct proc_dir_entry *proc_fs_nfs;

static int nfs_server_list_open(struct inode *inode, struct file *file);
static void *nfs_server_list_start(struct seq_file *p, loff_t *pos);
static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos);
static void nfs_server_list_stop(struct seq_file *p, void *v);
static int nfs_server_list_show(struct seq_file *m, void *v);

static const struct seq_operations nfs_server_list_ops = {
    .start  = nfs_server_list_start,
    .next   = nfs_server_list_next,
    .stop   = nfs_server_list_stop,
    .show   = nfs_server_list_show,
};

static const struct file_operations nfs_server_list_fops = {
    .open       = nfs_server_list_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
    .owner      = THIS_MODULE,
};

static int nfs_volume_list_open(struct inode *inode, struct file *file);
static void *nfs_volume_list_start(struct seq_file *p, loff_t *pos);
static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos);
static void nfs_volume_list_stop(struct seq_file *p, void *v);
static int nfs_volume_list_show(struct seq_file *m, void *v);

static const struct seq_operations nfs_volume_list_ops = {
    .start  = nfs_volume_list_start,
    .next   = nfs_volume_list_next,
    .stop   = nfs_volume_list_stop,
    .show   = nfs_volume_list_show,
};

static const struct file_operations nfs_volume_list_fops = {
    .open       = nfs_volume_list_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
    .owner      = THIS_MODULE,
};

/*
 * open "/proc/fs/nfsfs/servers" which provides a summary of servers with which
 * we're dealing
 */
static int nfs_server_list_open(struct inode *inode, struct file *file)
{
    struct seq_file *m;
    int ret;
    struct pid_namespace *pid_ns = file->f_dentry->d_sb->s_fs_info;
    struct net *net = pid_ns->child_reaper->nsproxy->net_ns;

    ret = seq_open(file, &nfs_server_list_ops);
    if (ret < 0)
        return ret;

    m = file->private_data;
    m->private = net;

    return 0;
}

/*
 * set up the iterator to start reading from the server list and return the first item
 */
static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos)
{
    struct nfs_net *nn = net_generic(m->private, nfs_net_id);

    /* lock the list against modification */
    spin_lock(&nn->nfs_client_lock);
    return seq_list_start_head(&nn->nfs_client_list, *_pos);
}

/*
 * move to next server
 */
static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
{
    struct nfs_net *nn = net_generic(p->private, nfs_net_id);

    return seq_list_next(v, &nn->nfs_client_list, pos);
}

/*
 * clean up after reading from the transports list
 */
static void nfs_server_list_stop(struct seq_file *p, void *v)
{
    struct nfs_net *nn = net_generic(p->private, nfs_net_id);

    spin_unlock(&nn->nfs_client_lock);
}

/*
 * display a header line followed by a load of call lines
 */
static int nfs_server_list_show(struct seq_file *m, void *v)
{
    struct nfs_client *clp;
    struct nfs_net *nn = net_generic(m->private, nfs_net_id);

    /* display header on line 1 */
    if (v == &nn->nfs_client_list) {
        seq_puts(m, "NV SERVER   PORT USE HOSTNAME\n");
        return 0;
    }

    /* display one transport per line on subsequent lines */
    clp = list_entry(v, struct nfs_client, cl_share_link);

    /* Check if the client is initialized */
    if (clp->cl_cons_state != NFS_CS_READY)
        return 0;

    rcu_read_lock();
    seq_printf(m, "v%u %s %s %3d %s\n",
           clp->rpc_ops->version,
           rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
           rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),
           atomic_read(&clp->cl_count),
           clp->cl_hostname);
    rcu_read_unlock();

    return 0;
}

/*
 * open "/proc/fs/nfsfs/volumes" which provides a summary of extant volumes
 */
static int nfs_volume_list_open(struct inode *inode, struct file *file)
{
    struct seq_file *m;
    int ret;
    struct pid_namespace *pid_ns = file->f_dentry->d_sb->s_fs_info;
    struct net *net = pid_ns->child_reaper->nsproxy->net_ns;

    ret = seq_open(file, &nfs_volume_list_ops);
    if (ret < 0)
        return ret;

    m = file->private_data;
    m->private = net;

    return 0;
}

/*
 * set up the iterator to start reading from the volume list and return the first item
 */
static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos)
{
    struct nfs_net *nn = net_generic(m->private, nfs_net_id);

    /* lock the list against modification */
    spin_lock(&nn->nfs_client_lock);
    return seq_list_start_head(&nn->nfs_volume_list, *_pos);
}

/*
 * move to next volume
 */
static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
{
    struct nfs_net *nn = net_generic(p->private, nfs_net_id);

    return seq_list_next(v, &nn->nfs_volume_list, pos);
}

/*
 * clean up after reading from the transports list
 */
static void nfs_volume_list_stop(struct seq_file *p, void *v)
{
    struct nfs_net *nn = net_generic(p->private, nfs_net_id);

    spin_unlock(&nn->nfs_client_lock);
}

/*
 * display a header line followed by a load of call lines
 */
static int nfs_volume_list_show(struct seq_file *m, void *v)
{
    struct nfs_server *server;
    struct nfs_client *clp;
    char dev[8], fsid[17];
    struct nfs_net *nn = net_generic(m->private, nfs_net_id);

    /* display header on line 1 */
    if (v == &nn->nfs_volume_list) {
        seq_puts(m, "NV SERVER   PORT DEV     FSID              FSC\n");
        return 0;
    }
    /* display one transport per line on subsequent lines */
    server = list_entry(v, struct nfs_server, master_link);
    clp = server->nfs_client;

    snprintf(dev, 8, "%u:%u",
         MAJOR(server->s_dev), MINOR(server->s_dev));

    snprintf(fsid, 17, "%llx:%llx",
         (unsigned long long) server->fsid.major,
         (unsigned long long) server->fsid.minor);

    rcu_read_lock();
    seq_printf(m, "v%u %s %s %-7s %-17s %s\n",
           clp->rpc_ops->version,
           rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
           rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),
           dev,
           fsid,
           nfs_server_fscache_state(server));
    rcu_read_unlock();

    return 0;
}

/*
 * initialise the /proc/fs/nfsfs/ directory
 */
int __init nfs_fs_proc_init(void)
{
    struct proc_dir_entry *p;

    proc_fs_nfs = proc_mkdir("fs/nfsfs", NULL);
    if (!proc_fs_nfs)
        goto error_0;

    /* a file of servers with which we're dealing */
    p = proc_create("servers", S_IFREG|S_IRUGO,
            proc_fs_nfs, &nfs_server_list_fops);
    if (!p)
        goto error_1;

    /* a file of volumes that we have mounted */
    p = proc_create("volumes", S_IFREG|S_IRUGO,
            proc_fs_nfs, &nfs_volume_list_fops);
    if (!p)
        goto error_2;
    return 0;

error_2:
    remove_proc_entry("servers", proc_fs_nfs);
error_1:
    remove_proc_entry("fs/nfsfs", NULL);
error_0:
    return -ENOMEM;
}

/*
 * clean up the /proc/fs/nfsfs/ directory
 */
void nfs_fs_proc_exit(void)
{
    remove_proc_entry("volumes", proc_fs_nfs);
    remove_proc_entry("servers", proc_fs_nfs);
    remove_proc_entry("fs/nfsfs", NULL);
}

#endif /* CONFIG_PROC_FS */