[PPPOL2TP]: Add CONFIG_INET Kconfig dependency.

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / nfs / client.c

/* client.c: NFS client sharing and management code
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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/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/nfs_xdr.h>

#include <asm/system.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "iostat.h"
#include "internal.h"

#define NFSDBG_FACILITY         NFSDBG_CLIENT

static DEFINE_SPINLOCK(nfs_client_lock);
static LIST_HEAD(nfs_client_list);
static LIST_HEAD(nfs_volume_list);
static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);

/*
 * RPC cruft for NFS
 */
static struct rpc_version *nfs_version[5] = {
        [2]                     = &nfs_version2,
#ifdef CONFIG_NFS_V3
        [3]                     = &nfs_version3,
#endif
#ifdef CONFIG_NFS_V4
        [4]                     = &nfs_version4,
#endif
};

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",
};

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


#ifdef CONFIG_NFS_V3_ACL
static struct rpc_stat          nfsacl_rpcstat = { &nfsacl_program };
static struct rpc_version *     nfsacl_version[] = {
        [3]                     = &nfsacl_version3,
};

struct rpc_program              nfsacl_program = {
        .name                   = "nfsacl",
        .number                 = NFS_ACL_PROGRAM,
        .nrvers                 = ARRAY_SIZE(nfsacl_version),
        .version                = nfsacl_version,
        .stats                  = &nfsacl_rpcstat,
};
#endif  /* CONFIG_NFS_V3_ACL */

/*
 * Allocate a shared client record
 *
 * Since these are allocated/deallocated very rarely, we don't
 * bother putting them in a slab cache...
 */
static struct nfs_client *nfs_alloc_client(const char *hostname,
                                           const struct sockaddr_in *addr,
                                           int nfsversion)
{
        struct nfs_client *clp;

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

        if (nfsversion == 4) {
                if (nfs_callback_up() < 0)
                        goto error_2;
                __set_bit(NFS_CS_CALLBACK, &clp->cl_res_state);
        }

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

        clp->cl_nfsversion = nfsversion;
        memcpy(&clp->cl_addr, addr, sizeof(clp->cl_addr));

        if (hostname) {
                clp->cl_hostname = kstrdup(hostname, GFP_KERNEL);
                if (!clp->cl_hostname)
                        goto error_3;
        }

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

#ifdef CONFIG_NFS_V4
        init_rwsem(&clp->cl_sem);
        INIT_LIST_HEAD(&clp->cl_delegations);
        spin_lock_init(&clp->cl_lock);
        INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
        rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
        clp->cl_boot_time = CURRENT_TIME;
        clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;
#endif

        return clp;

error_3:
        if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
                nfs_callback_down();
error_2:
        kfree(clp);
error_0:
        return NULL;
}

static void nfs4_shutdown_client(struct nfs_client *clp)
{
#ifdef CONFIG_NFS_V4
        if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
                nfs4_kill_renewd(clp);
        BUG_ON(!RB_EMPTY_ROOT(&clp->cl_state_owners));
        if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
                nfs_idmap_delete(clp);
#endif
}

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

        nfs4_shutdown_client(clp);

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

        if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
                nfs_callback_down();

        kfree(clp->cl_hostname);
        kfree(clp);

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

/*
 * Release a reference to a shared client record
 */
void nfs_put_client(struct nfs_client *clp)
{
        if (!clp)
                return;

        dprintk("--> nfs_put_client({%d})\n", atomic_read(&clp->cl_count));

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

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

                nfs_free_client(clp);
        }
}

/*
 * Find a client by address
 * - caller must hold nfs_client_lock
 */
static struct nfs_client *__nfs_find_client(const struct sockaddr_in *addr, int nfsversion, int match_port)
{
        struct nfs_client *clp;

        list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
                /* 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->cl_nfsversion != nfsversion)
                        continue;

                if (memcmp(&clp->cl_addr.sin_addr, &addr->sin_addr,
                           sizeof(clp->cl_addr.sin_addr)) != 0)
                        continue;

                if (!match_port || clp->cl_addr.sin_port == addr->sin_port)
                        goto found;
        }

        return NULL;

found:
        atomic_inc(&clp->cl_count);
        return clp;
}

/*
 * Find a client by IP address and protocol version
 * - returns NULL if no such client
 */
struct nfs_client *nfs_find_client(const struct sockaddr_in *addr, int nfsversion)
{
        struct nfs_client *clp;

        spin_lock(&nfs_client_lock);
        clp = __nfs_find_client(addr, nfsversion, 0);
        spin_unlock(&nfs_client_lock);
        if (clp != NULL && clp->cl_cons_state != NFS_CS_READY) {
                nfs_put_client(clp);
                clp = NULL;
        }
        return clp;
}

/*
 * Look up a client by IP address and protocol version
 * - creates a new record if one doesn't yet exist
 */
static struct nfs_client *nfs_get_client(const char *hostname,
                                         const struct sockaddr_in *addr,
                                         int nfsversion)
{
        struct nfs_client *clp, *new = NULL;
        int error;

        dprintk("--> nfs_get_client(%s,"NIPQUAD_FMT":%d,%d)\n",
                hostname ?: "", NIPQUAD(addr->sin_addr),
                addr->sin_port, nfsversion);

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

                clp = __nfs_find_client(addr, nfsversion, 1);
                if (clp)
                        goto found_client;
                if (new)
                        goto install_client;

                spin_unlock(&nfs_client_lock);

                new = nfs_alloc_client(hostname, addr, nfsversion);
        } while (new);

        return ERR_PTR(-ENOMEM);

        /* install a new client and return with it unready */
install_client:
        clp = new;
        list_add(&clp->cl_share_link, &nfs_client_list);
        spin_unlock(&nfs_client_lock);
        dprintk("--> nfs_get_client() = %p [new]\n", clp);
        return clp;

        /* found an existing client
         * - make sure it's ready before returning
         */
found_client:
        spin_unlock(&nfs_client_lock);

        if (new)
                nfs_free_client(new);

        error = wait_event_interruptible(nfs_client_active_wq,
                                clp->cl_cons_state != NFS_CS_INITING);
        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);
        }

        BUG_ON(clp->cl_cons_state != NFS_CS_READY);

        dprintk("--> nfs_get_client() = %p [share]\n", clp);
        return clp;
}

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

/*
 * Initialise the timeout values for a connection
 */
static 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;
        if (!to->to_retries)
                to->to_retries = 2;

        switch (proto) {
        case IPPROTO_TCP:
                if (!to->to_initval)
                        to->to_initval = 60 * HZ;
                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);
                to->to_exponential = 0;
                break;
        case IPPROTO_UDP:
        default:
                if (!to->to_initval)
                        to->to_initval = 11 * 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;
        }
}

/*
 * Create an RPC client handle
 */
static int nfs_create_rpc_client(struct nfs_client *clp, int proto,
                                                unsigned int timeo,
                                                unsigned int retrans,
                                                rpc_authflavor_t flavor,
                                                int flags)
{
        struct rpc_timeout      timeparms;
        struct rpc_clnt         *clnt = NULL;
        struct rpc_create_args args = {
                .protocol       = proto,
                .address        = (struct sockaddr *)&clp->cl_addr,
                .addrsize       = sizeof(clp->cl_addr),
                .timeout        = &timeparms,
                .servername     = clp->cl_hostname,
                .program        = &nfs_program,
                .version        = clp->rpc_ops->version,
                .authflavor     = flavor,
                .flags          = flags,
        };

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

        nfs_init_timeout_values(&timeparms, proto, timeo, retrans);
        clp->retrans_timeo = timeparms.to_initval;
        clp->retrans_count = timeparms.to_retries;

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

        clp->cl_rpcclient = clnt;
        return 0;
}

/*
 * Version 2 or 3 client destruction
 */
static void nfs_destroy_server(struct nfs_server *server)
{
        if (!IS_ERR(server->client_acl))
                rpc_shutdown_client(server->client_acl);

        if (!(server->flags & NFS_MOUNT_NONLM))
                lockd_down();   /* release rpc.lockd */
}

/*
 * Version 2 or 3 lockd setup
 */
static int nfs_start_lockd(struct nfs_server *server)
{
        int error = 0;

        if (server->nfs_client->cl_nfsversion > 3)
                goto out;
        if (server->flags & NFS_MOUNT_NONLM)
                goto out;
        error = lockd_up((server->flags & NFS_MOUNT_TCP) ?
                        IPPROTO_TCP : IPPROTO_UDP);
        if (error < 0)
                server->flags |= NFS_MOUNT_NONLM;
        else
                server->destroy = nfs_destroy_server;
out:
        return error;
}

/*
 * Initialise an NFSv3 ACL client connection
 */
#ifdef CONFIG_NFS_V3_ACL
static void nfs_init_server_aclclient(struct nfs_server *server)
{
        if (server->nfs_client->cl_nfsversion != 3)
                goto out_noacl;
        if (server->flags & NFS_MOUNT_NOACL)
                goto out_noacl;

        server->client_acl = rpc_bind_new_program(server->client, &nfsacl_program, 3);
        if (IS_ERR(server->client_acl))
                goto out_noacl;

        /* No errors! Assume that Sun nfsacls are supported */
        server->caps |= NFS_CAP_ACLS;
        return;

out_noacl:
        server->caps &= ~NFS_CAP_ACLS;
}
#else
static inline void nfs_init_server_aclclient(struct nfs_server *server)
{
        server->flags &= ~NFS_MOUNT_NOACL;
        server->caps &= ~NFS_CAP_ACLS;
}
#endif

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

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

        if (pseudoflavour != clp->cl_rpcclient->cl_auth->au_flavor) {
                struct rpc_auth *auth;

                auth = rpcauth_create(pseudoflavour, server->client);
                if (IS_ERR(auth)) {
                        dprintk("%s: couldn't create credcache!\n", __FUNCTION__);
                        return PTR_ERR(auth);
                }
        }
        server->client->cl_softrtry = 0;
        if (server->flags & NFS_MOUNT_SOFT)
                server->client->cl_softrtry = 1;

        server->client->cl_intr = 0;
        if (server->flags & NFS4_MOUNT_INTR)
                server->client->cl_intr = 1;

        return 0;
}

/*
 * Initialise an NFS2 or NFS3 client
 */
static int nfs_init_client(struct nfs_client *clp, const struct nfs_mount_data *data)
{
        int proto = (data->flags & NFS_MOUNT_TCP) ? IPPROTO_TCP : IPPROTO_UDP;
        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 0;
        }

        /* Check NFS protocol revision and initialize RPC op vector */
        clp->rpc_ops = &nfs_v2_clientops;
#ifdef CONFIG_NFS_V3
        if (clp->cl_nfsversion == 3)
                clp->rpc_ops = &nfs_v3_clientops;
#endif
        /*
         * Create a client RPC handle for doing FSSTAT with UNIX auth only
         * - RFC 2623, sec 2.3.2
         */
        error = nfs_create_rpc_client(clp, proto, data->timeo, data->retrans,
                                        RPC_AUTH_UNIX, 0);
        if (error < 0)
                goto error;
        nfs_mark_client_ready(clp, NFS_CS_READY);
        return 0;

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

/*
 * Create a version 2 or 3 client
 */
static int nfs_init_server(struct nfs_server *server, const struct nfs_mount_data *data)
{
        struct nfs_client *clp;
        int error, nfsvers = 2;

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

#ifdef CONFIG_NFS_V3
        if (data->flags & NFS_MOUNT_VER3)
                nfsvers = 3;
#endif

        /* Allocate or find a client reference we can use */
        clp = nfs_get_client(data->hostname, &data->addr, nfsvers);
        if (IS_ERR(clp)) {
                dprintk("<-- nfs_init_server() = error %ld\n", PTR_ERR(clp));
                return PTR_ERR(clp);
        }

        error = nfs_init_client(clp, data);
        if (error < 0)
                goto error;

        server->nfs_client = clp;

        /* Initialise the client representation from the mount data */
        server->flags = data->flags & NFS_MOUNT_FLAGMASK;

        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;

        error = nfs_init_server_rpcclient(server, data->pseudoflavor);
        if (error < 0)
                goto error;

        server->namelen  = data->namlen;
        /* Create a client RPC handle for the NFSv3 ACL management interface */
        nfs_init_server_aclclient(server);
        if (clp->cl_nfsversion == 3) {
                if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
                        server->namelen = NFS3_MAXNAMLEN;
                if (!(data->flags & NFS_MOUNT_NORDIRPLUS))
                        server->caps |= NFS_CAP_READDIRPLUS;
        } else {
                if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
                        server->namelen = NFS2_MAXNAMLEN;
        }

        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_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.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)
                server->dtsize = PAGE_CACHE_SIZE;
        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;

        /* 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
 */
static 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;
        nfs_fattr_init(fattr);
        error = clp->rpc_ops->fsinfo(server, mntfh, &fsinfo);
        if (error < 0)
                goto out_error;

        nfs_server_set_fsinfo(server, &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;
}

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

/*
 * Allocate and initialise a server record
 */
static 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);

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

        return server;
}

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

        spin_lock(&nfs_client_lock);
        list_del(&server->client_link);
        list_del(&server->master_link);
        spin_unlock(&nfs_client_lock);

        if (server->destroy != NULL)
                server->destroy(server);
        if (!IS_ERR(server->client))
                rpc_shutdown_client(server->client);

        nfs_put_client(server->nfs_client);

        nfs_free_iostats(server->io_stats);
        kfree(server);
        nfs_release_automount_timer();
        dprintk("<-- nfs_free_server()\n");
}

/*
 * Create a version 2 or 3 volume record
 * - keyed on server and FSID
 */
struct nfs_server *nfs_create_server(const struct nfs_mount_data *data,
                                     struct nfs_fh *mntfh)
{
        struct nfs_server *server;
        struct nfs_fattr fattr;
        int error;

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

        /* Get a client representation */
        error = nfs_init_server(server, data);
        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, mntfh, &fattr);
        if (error < 0)
                goto error;
        if (!(fattr.valid & NFS_ATTR_FATTR)) {
                error = server->nfs_client->rpc_ops->getattr(server, 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);

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

        spin_lock(&nfs_client_lock);
        list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
        list_add_tail(&server->master_link, &nfs_volume_list);
        spin_unlock(&nfs_client_lock);

        server->mount_time = jiffies;
        return server;

error:
        nfs_free_server(server);
        return ERR_PTR(error);
}

#ifdef CONFIG_NFS_V4
/*
 * Initialise an NFS4 client record
 */
static int nfs4_init_client(struct nfs_client *clp,
                int proto, int timeo, int retrans,
                const char *ip_addr,
                rpc_authflavor_t authflavour)
{
        int error;

        if (clp->cl_cons_state == NFS_CS_READY) {
                /* the client is initialised already */
                dprintk("<-- nfs4_init_client() = 0 [already %p]\n", clp);
                return 0;
        }

        /* Check NFS protocol revision and initialize RPC op vector */
        clp->rpc_ops = &nfs_v4_clientops;

        error = nfs_create_rpc_client(clp, proto, timeo, retrans, authflavour,
                                        RPC_CLNT_CREATE_DISCRTRY);
        if (error < 0)
                goto error;
        memcpy(clp->cl_ipaddr, ip_addr, sizeof(clp->cl_ipaddr));

        error = nfs_idmap_new(clp);
        if (error < 0) {
                dprintk("%s: failed to create idmapper. Error = %d\n",
                        __FUNCTION__, error);
                goto error;
        }
        __set_bit(NFS_CS_IDMAP, &clp->cl_res_state);

        nfs_mark_client_ready(clp, NFS_CS_READY);
        return 0;

error:
        nfs_mark_client_ready(clp, error);
        dprintk("<-- nfs4_init_client() = xerror %d\n", error);
        return error;
}

/*
 * Set up an NFS4 client
 */
static int nfs4_set_client(struct nfs_server *server,
                const char *hostname, const struct sockaddr_in *addr,
                const char *ip_addr,
                rpc_authflavor_t authflavour,
                int proto, int timeo, int retrans)
{
        struct nfs_client *clp;
        int error;

        dprintk("--> nfs4_set_client()\n");

        /* Allocate or find a client reference we can use */
        clp = nfs_get_client(hostname, addr, 4);
        if (IS_ERR(clp)) {
                error = PTR_ERR(clp);
                goto error;
        }
        error = nfs4_init_client(clp, proto, timeo, retrans, ip_addr, authflavour);
        if (error < 0)
                goto error_put;

        server->nfs_client = clp;
        dprintk("<-- nfs4_set_client() = 0 [new %p]\n", clp);
        return 0;

error_put:
        nfs_put_client(clp);
error:
        dprintk("<-- nfs4_set_client() = xerror %d\n", error);
        return error;
}

/*
 * Create a version 4 volume record
 */
static int nfs4_init_server(struct nfs_server *server,
                const struct nfs4_mount_data *data, rpc_authflavor_t authflavour)
{
        int error;

        dprintk("--> nfs4_init_server()\n");

        /* Initialise the client representation from the mount data */
        server->flags = data->flags & NFS_MOUNT_FLAGMASK;
        server->caps |= NFS_CAP_ATOMIC_OPEN;

        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;

        error = nfs_init_server_rpcclient(server, authflavour);

        /* Done */
        dprintk("<-- nfs4_init_server() = %d\n", error);
        return error;
}

/*
 * Create a version 4 volume record
 * - keyed on server and FSID
 */
struct nfs_server *nfs4_create_server(const struct nfs4_mount_data *data,
                                      const char *hostname,
                                      const struct sockaddr_in *addr,
                                      const char *mntpath,
                                      const char *ip_addr,
                                      rpc_authflavor_t authflavour,
                                      struct nfs_fh *mntfh)
{
        struct nfs_fattr fattr;
        struct nfs_server *server;
        int error;

        dprintk("--> nfs4_create_server()\n");

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

        /* Get a client record */
        error = nfs4_set_client(server, hostname, addr, ip_addr, authflavour,
                        data->proto, data->timeo, data->retrans);
        if (error < 0)
                goto error;

        /* set up the general RPC client */
        error = nfs4_init_server(server, data, authflavour);
        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 = nfs4_path_walk(server, mntfh, mntpath);
        if (error < 0)
                goto error;

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

        error = nfs_probe_fsinfo(server, mntfh, &fattr);
        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);

        spin_lock(&nfs_client_lock);
        list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
        list_add_tail(&server->master_link, &nfs_volume_list);
        spin_unlock(&nfs_client_lock);

        server->mount_time = jiffies;
        dprintk("<-- nfs4_create_server() = %p\n", server);
        return server;

error:
        nfs_free_server(server);
        dprintk("<-- nfs4_create_server() = error %d\n", error);
        return ERR_PTR(error);
}

/*
 * Create an NFS4 referral server record
 */
struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
                                               struct nfs_fh *mntfh)
{
        struct nfs_client *parent_client;
        struct nfs_server *server, *parent_server;
        struct nfs_fattr fattr;
        int error;

        dprintk("--> nfs4_create_referral_server()\n");

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

        parent_server = NFS_SB(data->sb);
        parent_client = parent_server->nfs_client;

        /* Get a client representation.
         * Note: NFSv4 always uses TCP, */
        error = nfs4_set_client(server, data->hostname, data->addr,
                        parent_client->cl_ipaddr,
                        data->authflavor,
                        parent_server->client->cl_xprt->prot,
                        parent_client->retrans_timeo,
                        parent_client->retrans_count);
        if (error < 0)
                goto error;

        /* Initialise the client representation from the parent server */
        nfs_server_copy_userdata(server, parent_server);
        server->caps |= NFS_CAP_ATOMIC_OPEN;

        error = nfs_init_server_rpcclient(server, data->authflavor);
        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 and filehandle */
        error = nfs4_path_walk(server, mntfh, data->mnt_path);
        if (error < 0)
                goto error;

        /* probe the filesystem info for this server filesystem */
        error = nfs_probe_fsinfo(server, mntfh, &fattr);
        if (error < 0)
                goto error;

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

        spin_lock(&nfs_client_lock);
        list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
        list_add_tail(&server->master_link, &nfs_volume_list);
        spin_unlock(&nfs_client_lock);

        server->mount_time = jiffies;

        dprintk("<-- nfs_create_referral_server() = %p\n", server);
        return server;

error:
        nfs_free_server(server);
        dprintk("<-- nfs4_create_referral_server() = error %d\n", error);
        return ERR_PTR(error);
}

#endif /* CONFIG_NFS_V4 */

/*
 * 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)
{
        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);

        /* Copy data from the source */
        server->nfs_client = source->nfs_client;
        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_auth->au_flavor);
        if (error < 0)
                goto out_free_server;
        if (!IS_ERR(source->client_acl))
                nfs_init_server_aclclient(server);

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

        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;

        spin_lock(&nfs_client_lock);
        list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
        list_add_tail(&server->master_link, &nfs_volume_list);
        spin_unlock(&nfs_client_lock);

        server->mount_time = jiffies;

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

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

#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 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,
};

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 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,
};

/*
 * 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;

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

        m = file->private_data;
        m->private = PDE(inode)->data;

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

/*
 * move to next server
 */
static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
{
        return seq_list_next(v, &nfs_client_list, pos);
}

/*
 * clean up after reading from the transports list
 */
static void nfs_server_list_stop(struct seq_file *p, void *v)
{
        spin_unlock(&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;

        /* display header on line 1 */
        if (v == &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);

        seq_printf(m, "v%d %02x%02x%02x%02x %4hx %3d %s\n",
                   clp->cl_nfsversion,
                   NIPQUAD(clp->cl_addr.sin_addr),
                   ntohs(clp->cl_addr.sin_port),
                   atomic_read(&clp->cl_count),
                   clp->cl_hostname);

        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;

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

        m = file->private_data;
        m->private = PDE(inode)->data;

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

/*
 * move to next volume
 */
static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
{
        return seq_list_next(v, &nfs_volume_list, pos);
}

/*
 * clean up after reading from the transports list
 */
static void nfs_volume_list_stop(struct seq_file *p, void *v)
{
        spin_unlock(&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];

        /* display header on line 1 */
        if (v == &nfs_volume_list) {
                seq_puts(m, "NV SERVER   PORT DEV     FSID\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);

        seq_printf(m, "v%d %02x%02x%02x%02x %4hx %-7s %-17s\n",
                   clp->cl_nfsversion,
                   NIPQUAD(clp->cl_addr.sin_addr),
                   ntohs(clp->cl_addr.sin_port),
                   dev,
                   fsid);

        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("nfsfs", proc_root_fs);
        if (!proc_fs_nfs)
                goto error_0;

        proc_fs_nfs->owner = THIS_MODULE;

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

        p->proc_fops = &nfs_server_list_fops;
        p->owner = THIS_MODULE;

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

        p->proc_fops = &nfs_volume_list_fops;
        p->owner = THIS_MODULE;
        return 0;

error_2:
        remove_proc_entry("servers", proc_fs_nfs);
error_1:
        remove_proc_entry("nfsfs", proc_root_fs);
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("nfsfs", proc_root_fs);
}

#endif /* CONFIG_PROC_FS */