ClabureDB: Classified Bug-Reports Database

   /* 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/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 <net/ipv6.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 */
  
  struct nfs_client_initdata {
          const char *hostname;
         const struct sockaddr *addr;
         size_t addrlen;
         const struct nfs_rpc_ops *rpc_ops;
         int proto;
 };
 
 /*
  * 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 struct nfs_client_initdata *cl_init)
 {
         struct nfs_client *clp;
         struct rpc_cred *cred;
 
         if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
                 goto error_0;
 
         clp->rpc_ops = cl_init->rpc_ops;
 
         if (cl_init->rpc_ops->version == 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;
 
         memcpy(&clp->cl_addr, cl_init->addr, cl_init->addrlen);
         clp->cl_addrlen = cl_init->addrlen;
 
         if (cl_init->hostname) {
                 clp->cl_hostname = kstrdup(cl_init->hostname, GFP_KERNEL);
                 if (!clp->cl_hostname)
                         goto error_3;
         }
 
         INIT_LIST_HEAD(&clp->cl_superblocks);
         clp->cl_rpcclient = ERR_PTR(-EINVAL);
 
         clp->cl_proto = cl_init->proto;
 
 #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
         cred = rpc_lookup_machine_cred();
         if (!IS_ERR(cred))
                 clp->cl_machine_cred = cred;
 
         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);
 
         rpc_destroy_wait_queue(&clp->cl_rpcwaitq);
 #endif
 }
 
 /*
  * Destroy a shared client record
  */
 static void nfs_free_client(struct nfs_client *clp)
 {
         dprintk("--> nfs_free_client(%u)\n", clp->rpc_ops->version);
 
         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();
 
         if (clp->cl_machine_cred != NULL)
                 put_rpccred(clp->cl_machine_cred);
 
         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);
         }
 }
 
 static int nfs_sockaddr_match_ipaddr4(const struct sockaddr_in *sa1,
                                  const struct sockaddr_in *sa2)
 {
         return sa1->sin_addr.s_addr == sa2->sin_addr.s_addr;
 }
 
 static int nfs_sockaddr_match_ipaddr6(const struct sockaddr_in6 *sa1,
                                  const struct sockaddr_in6 *sa2)
 {
         return ipv6_addr_equal(&sa1->sin6_addr, &sa2->sin6_addr);
 }
 
 static int nfs_sockaddr_match_ipaddr(const struct sockaddr *sa1,
                                  const struct sockaddr *sa2)
 {
         switch (sa1->sa_family) {
         case AF_INET:
                 return nfs_sockaddr_match_ipaddr4((const struct sockaddr_in *)sa1,
                                 (const struct sockaddr_in *)sa2);
         case AF_INET6:
                 return nfs_sockaddr_match_ipaddr6((const struct sockaddr_in6 *)sa1,
                                 (const struct sockaddr_in6 *)sa2);
         }
         BUG();
 }
 
 /*
  * Find a client by IP address and protocol version
  * - returns NULL if no such client
  */
 struct nfs_client *nfs_find_client(const struct sockaddr *addr, u32 nfsversion)
 {
         struct nfs_client *clp;
 
         spin_lock(&nfs_client_lock);
         list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
                 struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
 
                 /* Don't match clients that failed to initialise properly */
                 if (clp->cl_cons_state != NFS_CS_READY)
                         continue;
 
                 /* Different NFS versions cannot share the same nfs_client */
                 if (clp->rpc_ops->version != nfsversion)
                         continue;
 
                 if (addr->sa_family != clap->sa_family)
                         continue;
                 /* Match only the IP address, not the port number */
                 if (!nfs_sockaddr_match_ipaddr(addr, clap))
                         continue;
 
                 atomic_inc(&clp->cl_count);
                 spin_unlock(&nfs_client_lock);
                 return clp;
         }
         spin_unlock(&nfs_client_lock);
         return NULL;
 }
 
 /*
  * Find a client by IP address and protocol version
  * - returns NULL if no such client
  */
 struct nfs_client *nfs_find_client_next(struct nfs_client *clp)
 {
         struct sockaddr *sap = (struct sockaddr *)&clp->cl_addr;
         u32 nfsvers = clp->rpc_ops->version;
 
         spin_lock(&nfs_client_lock);
         list_for_each_entry_continue(clp, &nfs_client_list, cl_share_link) {
                 struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
 
                 /* Don't match clients that failed to initialise properly */
                 if (clp->cl_cons_state != NFS_CS_READY)
                         continue;
 
                 /* Different NFS versions cannot share the same nfs_client */
                 if (clp->rpc_ops->version != nfsvers)
                         continue;
 
                 if (sap->sa_family != clap->sa_family)
                         continue;
                 /* Match only the IP address, not the port number */
                 if (!nfs_sockaddr_match_ipaddr(sap, clap))
                         continue;
 
                 atomic_inc(&clp->cl_count);
                 spin_unlock(&nfs_client_lock);
                 return clp;
         }
         spin_unlock(&nfs_client_lock);
         return NULL;
 }
 
 /*
  * 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;
 
         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->rpc_ops != data->rpc_ops)
                         continue;
 
                 if (clp->cl_proto != data->proto)
                         continue;
 
                 /* Match the full socket address */
                 if (memcmp(&clp->cl_addr, data->addr, sizeof(clp->cl_addr)) != 0)
                         continue;
 
                 atomic_inc(&clp->cl_count);
                 return clp;
         }
         return NULL;
 }
 
 /*
  * 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 struct nfs_client_initdata *cl_init)
 {
         struct nfs_client *clp, *new = NULL;
         int error;
 
         dprintk("--> nfs_get_client(%s,v%u)\n",
                 cl_init->hostname ?: "", cl_init->rpc_ops->version);
 
         /* see if the client already exists */
         do {
                 spin_lock(&nfs_client_lock);
 
                 clp = nfs_match_client(cl_init);
                 if (clp)
                         goto found_client;
                 if (new)
                         goto install_client;
 
                 spin_unlock(&nfs_client_lock);
 
                 new = nfs_alloc_client(cl_init);
         } 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_killable(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;
 
         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();
         }
 }
 
 /*
  * Create an RPC client handle
  */
 static int nfs_create_rpc_client(struct nfs_client *clp,
                                  const struct rpc_timeout *timeparms,
                                  rpc_authflavor_t flavor,
                                  int flags)
 {
         struct rpc_clnt                *clnt = NULL;
         struct rpc_create_args args = {
                 .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,
                 .flags                = flags,
         };
 
         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;
 }
 
 /*
  * Version 2 or 3 client destruction
  */
 static void nfs_destroy_server(struct nfs_server *server)
 {
         if (!(server->flags & NFS_MOUNT_NONLM))
                 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,
                 .protocol        = server->flags & NFS_MOUNT_TCP ?
                                                 IPPROTO_TCP : IPPROTO_UDP,
                 .nfs_version        = clp->rpc_ops->version,
         };
 
         if (nlm_init.nfs_version > 3)
                 return 0;
         if (server->flags & NFS_MOUNT_NONLM)
                 return 0;
 
         host = nlmclnt_init(&nlm_init);
         if (IS_ERR(host))
                 return PTR_ERR(host);
 
         server->nlm_host = host;
         server->destroy = nfs_destroy_server;
         return 0;
 }
 
 /*
  * 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->rpc_ops->version != 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,
                 const struct rpc_timeout *timeo,
                 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", __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;
 
         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", __func__);
                         return PTR_ERR(auth);
                 }
         }
         server->client->cl_softrtry = 0;
         if (server->flags & NFS_MOUNT_SOFT)
                 server->client->cl_softrtry = 1;
 
         return 0;
 }
 
 /*
  * Initialise an NFS2 or NFS3 client
  */
 static int nfs_init_client(struct nfs_client *clp,
                            const struct rpc_timeout *timeparms,
                            const struct nfs_parsed_mount_data *data)
 {
         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;
         }
 
         /*
          * 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, 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_parsed_mount_data *data)
 {
         struct nfs_client_initdata cl_init = {
                 .hostname = data->nfs_server.hostname,
                 .addr = (const struct sockaddr *)&data->nfs_server.address,
                 .addrlen = data->nfs_server.addrlen,
                 .rpc_ops = &nfs_v2_clientops,
                 .proto = data->nfs_server.protocol,
         };
         struct rpc_timeout timeparms;
         struct nfs_client *clp;
         int error;
 
         dprintk("--> nfs_init_server()\n");
 
 #ifdef CONFIG_NFS_V3
         if (data->flags & NFS_MOUNT_VER3)
                 cl_init.rpc_ops = &nfs_v3_clientops;
 #endif
 
         /* Allocate or find a client reference we can use */
         clp = nfs_get_client(&cl_init);
         if (IS_ERR(clp)) {
                 dprintk("<-- nfs_init_server() = error %ld\n", PTR_ERR(clp));
                 return PTR_ERR(clp);
         }
 
         nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
                         data->timeo, data->retrans);
         error = nfs_init_client(clp, &timeparms, data);
         if (error < 0)
                 goto error;
 
         server->nfs_client = clp;
 
         /* Initialise the client representation from the mount data */
         server->flags = data->flags;
 
         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;
         /* Create a client RPC handle for the NFSv3 ACL management interface */
         nfs_init_server_aclclient(server);
         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);
         error = bdi_init(&server->backing_dev_info);
         if (error)
                 goto out_error;
 
 
         /* 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);
 
         atomic_set(&server->active, 0);
 
         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_acl))
                 rpc_shutdown_client(server->client_acl);
         if (!IS_ERR(server->client))
                 rpc_shutdown_client(server->client);
 
         nfs_put_client(server->nfs_client);
 
         nfs_free_iostats(server->io_stats);
         bdi_destroy(&server->backing_dev_info);
         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_parsed_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 (server->nfs_client->rpc_ops->version == 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;
         }
 
         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,
                 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 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, timeparms, 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",
                         __func__, 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 *addr,
                const size_t addrlen,
                const char *ip_addr,
                rpc_authflavor_t authflavour,
                int proto, const struct rpc_timeout *timeparms)
{
        struct nfs_client_initdata cl_init = {
                .hostname = hostname,
                .addr = addr,
                .addrlen = addrlen,
                .rpc_ops = &nfs_v4_clientops,
                .proto = proto,
        };
        struct nfs_client *clp;
        int error;

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

        /* Allocate or find a client reference we can use */
        clp = nfs_get_client(&cl_init);
        if (IS_ERR(clp)) {
                error = PTR_ERR(clp);
                goto error;
        }
        error = nfs4_init_client(clp, timeparms, 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 nfs_parsed_mount_data *data)
{
        struct rpc_timeout timeparms;
        int error;

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

        nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
                        data->timeo, data->retrans);

        /* Get a client record */
        error = nfs4_set_client(server,
                        data->nfs_server.hostname,
                        (const struct sockaddr *)&data->nfs_server.address,
                        data->nfs_server.addrlen,
                        data->client_address,
                        data->auth_flavors[0],
                        data->nfs_server.protocol,
                        &timeparms);
        if (error < 0)
                goto error;

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

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

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

error:
        /* 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 nfs_parsed_mount_data *data,
                                      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);

        /* set up the general RPC client */
        error = nfs4_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 = nfs4_path_walk(server, mntfh, data->nfs_server.export_path);
        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;

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

        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,
                                data->addrlen,
                                parent_client->cl_ipaddr,
                                data->authflavor,
                                parent_server->client->cl_xprt->prot,
                                parent_server->client->cl_timeout);
        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, parent_server->client->cl_timeout, 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;

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

        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_timeout,
                        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;

        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;

        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,
        .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 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;

        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%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);

        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%u %s %s %-7s %-17s\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);

        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;

        proc_fs_nfs->owner = THIS_MODULE;

        /* 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 */