This commit was manufactured by cvs2svn to create branch 'vserver'.
[linux-2.6.git] / fs / nfs / client.c
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
new file mode 100644 (file)
index 0000000..aa9e412
--- /dev/null
@@ -0,0 +1,1436 @@
+/* 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/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/smp_lock.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;
+       int error;
+
+       if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
+               goto error_0;
+
+       error = rpciod_up();
+       if (error < 0) {
+               dprintk("%s: couldn't start rpciod! Error = %d\n",
+                               __FUNCTION__, error);
+               goto error_1;
+       }
+       __set_bit(NFS_CS_RPCIOD, &clp->cl_res_state);
+
+       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);
+       INIT_LIST_HEAD(&clp->cl_state_owners);
+       INIT_LIST_HEAD(&clp->cl_unused);
+       spin_lock_init(&clp->cl_lock);
+       INIT_WORK(&clp->cl_renewd, nfs4_renew_state, clp);
+       rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
+       clp->cl_boot_time = CURRENT_TIME;
+       clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;
+#endif
+
+       nfs_fscache_get_client_cookie(clp);
+
+       return clp;
+
+error_3:
+       if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
+               nfs_callback_down();
+error_2:
+       rpciod_down();
+       __clear_bit(NFS_CS_RPCIOD, &clp->cl_res_state);
+error_1:
+       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);
+       while (!list_empty(&clp->cl_unused)) {
+               struct nfs4_state_owner *sp;
+
+               sp = list_entry(clp->cl_unused.next,
+                               struct nfs4_state_owner,
+                               so_list);
+               list_del(&sp->so_list);
+               kfree(sp);
+       }
+       BUG_ON(!list_empty(&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);
+
+       nfs_fscache_release_client_cookie(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 (__test_and_clear_bit(NFS_CS_RPCIOD, &clp->cl_res_state))
+               rpciod_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)
+{
+       struct nfs_client *clp;
+
+       list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
+               /* 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 (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);
+       spin_unlock(&nfs_client_lock);
+
+       BUG_ON(clp->cl_cons_state == 0);
+
+       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);
+               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)
+{
+       struct rpc_timeout      timeparms;
+       struct rpc_xprt         *xprt = NULL;
+       struct rpc_clnt         *clnt = NULL;
+
+       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;
+
+       /* create transport and client */
+       xprt = xprt_create_proto(proto, &clp->cl_addr, &timeparms);
+       if (IS_ERR(xprt)) {
+               dprintk("%s: cannot create RPC transport. Error = %ld\n",
+                               __FUNCTION__, PTR_ERR(xprt));
+               return PTR_ERR(xprt);
+       }
+
+       /* Bind to a reserved port! */
+       xprt->resvport = 1;
+       /* Create the client RPC handle */
+       clnt = rpc_create_client(xprt, clp->cl_hostname, &nfs_program,
+                                clp->rpc_ops->version, RPC_AUTH_UNIX);
+       if (IS_ERR(clnt)) {
+               dprintk("%s: cannot create RPC client. Error = %ld\n",
+                               __FUNCTION__, PTR_ERR(clnt));
+               return PTR_ERR(clnt);
+       }
+
+       clnt->cl_intr     = 1;
+       clnt->cl_softrtry = 1;
+       clnt->cl_tagxid   = 1;
+       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();
+       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;
+
+       server->client->cl_tagxid = (server->flags & NFS_MOUNT_TAGXID) ? 1 : 0;
+
+       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);
+       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;
+               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", server->fsid.major, 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,
+               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);
+       if (error < 0)
+               goto error;
+
+       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,
+               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, 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, 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", server->fsid.major, 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 *fh)
+{
+       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->authflavor,
+                       parent_server->client->cl_xprt->prot,
+                       parent_client->retrans_timeo,
+                       parent_client->retrans_count);
+
+       /* 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 filesystem info for this server filesystem */
+       error = nfs_probe_fsinfo(server, fh, &fattr);
+       if (error < 0)
+               goto error;
+
+       dprintk("Referral FSID: %llx:%llx\n",
+               server->fsid.major, 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",
+               fattr->fsid.major, 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",
+               server->fsid.major, 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 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 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)
+{
+       struct list_head *_p;
+       loff_t pos = *_pos;
+
+       /* lock the list against modification */
+       spin_lock(&nfs_client_lock);
+
+       /* allow for the header line */
+       if (!pos)
+               return SEQ_START_TOKEN;
+       pos--;
+
+       /* find the n'th element in the list */
+       list_for_each(_p, &nfs_client_list)
+               if (!pos--)
+                       break;
+
+       return _p != &nfs_client_list ? _p : NULL;
+}
+
+/*
+ * move to next server
+ */
+static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
+{
+       struct list_head *_p;
+
+       (*pos)++;
+
+       _p = v;
+       _p = (v == SEQ_START_TOKEN) ? nfs_client_list.next : _p->next;
+
+       return _p != &nfs_client_list ? _p : NULL;
+}
+
+/*
+ * 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 == SEQ_START_TOKEN) {
+               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)
+{
+       struct list_head *_p;
+       loff_t pos = *_pos;
+
+       /* lock the list against modification */
+       spin_lock(&nfs_client_lock);
+
+       /* allow for the header line */
+       if (!pos)
+               return SEQ_START_TOKEN;
+       pos--;
+
+       /* find the n'th element in the list */
+       list_for_each(_p, &nfs_volume_list)
+               if (!pos--)
+                       break;
+
+       return _p != &nfs_volume_list ? _p : NULL;
+}
+
+/*
+ * move to next volume
+ */
+static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
+{
+       struct list_head *_p;
+
+       (*pos)++;
+
+       _p = v;
+       _p = (v == SEQ_START_TOKEN) ? nfs_volume_list.next : _p->next;
+
+       return _p != &nfs_volume_list ? _p : NULL;
+}
+
+/*
+ * 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 == SEQ_START_TOKEN) {
+               seq_puts(m, "NV SERVER   PORT DEV     FSID              FSC\n");
+               return 0;
+       }
+       /* display one transport per line on subsequent lines */
+       server = list_entry(v, struct nfs_server, master_link);
+       clp = server->nfs_client;
+
+       snprintf(dev, 8, "%u:%u",
+                MAJOR(server->s_dev), MINOR(server->s_dev));
+
+       snprintf(fsid, 17, "%llx:%llx",
+                server->fsid.major, server->fsid.minor);
+
+       seq_printf(m, "v%d %02x%02x%02x%02x %4hx %-7s %-17s %s\n",
+                  clp->cl_nfsversion,
+                  NIPQUAD(clp->cl_addr.sin_addr),
+                  ntohs(clp->cl_addr.sin_port),
+                  dev,
+                  fsid,
+                  nfs_server_fscache_state(server));
+
+       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 */