Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / fs / nfs / nfs4client.c
diff --git a/kernel/fs/nfs/nfs4client.c b/kernel/fs/nfs/nfs4client.c
new file mode 100644 (file)
index 0000000..e42be52
--- /dev/null
@@ -0,0 +1,1232 @@
+/*
+ * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#include <linux/module.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/auth.h>
+#include <linux/sunrpc/xprt.h>
+#include <linux/sunrpc/bc_xprt.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
+#include "internal.h"
+#include "callback.h"
+#include "delegation.h"
+#include "nfs4session.h"
+#include "nfs4idmap.h"
+#include "pnfs.h"
+#include "netns.h"
+
+#define NFSDBG_FACILITY                NFSDBG_CLIENT
+
+/*
+ * Get a unique NFSv4.0 callback identifier which will be used
+ * by the V4.0 callback service to lookup the nfs_client struct
+ */
+static int nfs_get_cb_ident_idr(struct nfs_client *clp, int minorversion)
+{
+       int ret = 0;
+       struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
+
+       if (clp->rpc_ops->version != 4 || minorversion != 0)
+               return ret;
+       idr_preload(GFP_KERNEL);
+       spin_lock(&nn->nfs_client_lock);
+       ret = idr_alloc(&nn->cb_ident_idr, clp, 0, 0, GFP_NOWAIT);
+       if (ret >= 0)
+               clp->cl_cb_ident = ret;
+       spin_unlock(&nn->nfs_client_lock);
+       idr_preload_end();
+       return ret < 0 ? ret : 0;
+}
+
+#ifdef CONFIG_NFS_V4_1
+/**
+ * Per auth flavor data server rpc clients
+ */
+struct nfs4_ds_server {
+       struct list_head        list;   /* ds_clp->cl_ds_clients */
+       struct rpc_clnt         *rpc_clnt;
+};
+
+/**
+ * Common lookup case for DS I/O
+ */
+static struct nfs4_ds_server *
+nfs4_find_ds_client(struct nfs_client *ds_clp, rpc_authflavor_t flavor)
+{
+       struct nfs4_ds_server *dss;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(dss, &ds_clp->cl_ds_clients, list) {
+               if (dss->rpc_clnt->cl_auth->au_flavor != flavor)
+                       continue;
+               goto out;
+       }
+       dss = NULL;
+out:
+       rcu_read_unlock();
+       return dss;
+}
+
+static struct nfs4_ds_server *
+nfs4_add_ds_client(struct nfs_client *ds_clp, rpc_authflavor_t flavor,
+                          struct nfs4_ds_server *new)
+{
+       struct nfs4_ds_server *dss;
+
+       spin_lock(&ds_clp->cl_lock);
+       list_for_each_entry(dss, &ds_clp->cl_ds_clients, list) {
+               if (dss->rpc_clnt->cl_auth->au_flavor != flavor)
+                       continue;
+               goto out;
+       }
+       if (new)
+               list_add_rcu(&new->list, &ds_clp->cl_ds_clients);
+       dss = new;
+out:
+       spin_unlock(&ds_clp->cl_lock); /* need some lock to protect list */
+       return dss;
+}
+
+static struct nfs4_ds_server *
+nfs4_alloc_ds_server(struct nfs_client *ds_clp, rpc_authflavor_t flavor)
+{
+       struct nfs4_ds_server *dss;
+
+       dss = kmalloc(sizeof(*dss), GFP_NOFS);
+       if (dss == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       dss->rpc_clnt = rpc_clone_client_set_auth(ds_clp->cl_rpcclient, flavor);
+       if (IS_ERR(dss->rpc_clnt)) {
+               int err = PTR_ERR(dss->rpc_clnt);
+               kfree (dss);
+               return ERR_PTR(err);
+       }
+       INIT_LIST_HEAD(&dss->list);
+
+       return dss;
+}
+
+static void
+nfs4_free_ds_server(struct nfs4_ds_server *dss)
+{
+       rpc_release_client(dss->rpc_clnt);
+       kfree(dss);
+}
+
+/**
+* Find or create a DS rpc client with th MDS server rpc client auth flavor
+* in the nfs_client cl_ds_clients list.
+*/
+struct rpc_clnt *
+nfs4_find_or_create_ds_client(struct nfs_client *ds_clp, struct inode *inode)
+{
+       struct nfs4_ds_server *dss, *new;
+       rpc_authflavor_t flavor = NFS_SERVER(inode)->client->cl_auth->au_flavor;
+
+       dss = nfs4_find_ds_client(ds_clp, flavor);
+       if (dss != NULL)
+               goto out;
+       new = nfs4_alloc_ds_server(ds_clp, flavor);
+       if (IS_ERR(new))
+               return ERR_CAST(new);
+       dss = nfs4_add_ds_client(ds_clp, flavor, new);
+       if (dss != new)
+               nfs4_free_ds_server(new);
+out:
+       return dss->rpc_clnt;
+}
+EXPORT_SYMBOL_GPL(nfs4_find_or_create_ds_client);
+
+static void
+nfs4_shutdown_ds_clients(struct nfs_client *clp)
+{
+       struct nfs4_ds_server *dss;
+       LIST_HEAD(shutdown_list);
+
+       while (!list_empty(&clp->cl_ds_clients)) {
+               dss = list_entry(clp->cl_ds_clients.next,
+                                       struct nfs4_ds_server, list);
+               list_del(&dss->list);
+               rpc_shutdown_client(dss->rpc_clnt);
+               kfree (dss);
+       }
+}
+
+void nfs41_shutdown_client(struct nfs_client *clp)
+{
+       if (nfs4_has_session(clp)) {
+               nfs4_shutdown_ds_clients(clp);
+               nfs4_destroy_session(clp->cl_session);
+               nfs4_destroy_clientid(clp);
+       }
+
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+void nfs40_shutdown_client(struct nfs_client *clp)
+{
+       if (clp->cl_slot_tbl) {
+               nfs4_shutdown_slot_table(clp->cl_slot_tbl);
+               kfree(clp->cl_slot_tbl);
+       }
+}
+
+struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *cl_init)
+{
+       int err;
+       struct nfs_client *clp = nfs_alloc_client(cl_init);
+       if (IS_ERR(clp))
+               return clp;
+
+       err = nfs_get_cb_ident_idr(clp, cl_init->minorversion);
+       if (err)
+               goto error;
+
+       if (cl_init->minorversion > NFS4_MAX_MINOR_VERSION) {
+               err = -EINVAL;
+               goto error;
+       }
+
+       spin_lock_init(&clp->cl_lock);
+       INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
+       INIT_LIST_HEAD(&clp->cl_ds_clients);
+       rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
+       clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;
+       clp->cl_minorversion = cl_init->minorversion;
+       clp->cl_mvops = nfs_v4_minor_ops[cl_init->minorversion];
+       clp->cl_mig_gen = 1;
+       return clp;
+
+error:
+       nfs_free_client(clp);
+       return ERR_PTR(err);
+}
+
+/*
+ * Destroy the NFS4 callback service
+ */
+static void nfs4_destroy_callback(struct nfs_client *clp)
+{
+       if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
+               nfs_callback_down(clp->cl_mvops->minor_version, clp->cl_net);
+}
+
+static void nfs4_shutdown_client(struct nfs_client *clp)
+{
+       if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
+               nfs4_kill_renewd(clp);
+       clp->cl_mvops->shutdown_client(clp);
+       nfs4_destroy_callback(clp);
+       if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
+               nfs_idmap_delete(clp);
+
+       rpc_destroy_wait_queue(&clp->cl_rpcwaitq);
+       kfree(clp->cl_serverowner);
+       kfree(clp->cl_serverscope);
+       kfree(clp->cl_implid);
+       kfree(clp->cl_owner_id);
+}
+
+void nfs4_free_client(struct nfs_client *clp)
+{
+       nfs4_shutdown_client(clp);
+       nfs_free_client(clp);
+}
+
+/*
+ * Initialize the NFS4 callback service
+ */
+static int nfs4_init_callback(struct nfs_client *clp)
+{
+       struct rpc_xprt *xprt;
+       int error;
+
+       xprt = rcu_dereference_raw(clp->cl_rpcclient->cl_xprt);
+
+       if (nfs4_has_session(clp)) {
+               error = xprt_setup_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
+               if (error < 0)
+                       return error;
+       }
+
+       error = nfs_callback_up(clp->cl_mvops->minor_version, xprt);
+       if (error < 0) {
+               dprintk("%s: failed to start callback. Error = %d\n",
+                       __func__, error);
+               return error;
+       }
+       __set_bit(NFS_CS_CALLBACK, &clp->cl_res_state);
+
+       return 0;
+}
+
+/**
+ * nfs40_init_client - nfs_client initialization tasks for NFSv4.0
+ * @clp - nfs_client to initialize
+ *
+ * Returns zero on success, or a negative errno if some error occurred.
+ */
+int nfs40_init_client(struct nfs_client *clp)
+{
+       struct nfs4_slot_table *tbl;
+       int ret;
+
+       tbl = kzalloc(sizeof(*tbl), GFP_NOFS);
+       if (tbl == NULL)
+               return -ENOMEM;
+
+       ret = nfs4_setup_slot_table(tbl, NFS4_MAX_SLOT_TABLE,
+                                       "NFSv4.0 transport Slot table");
+       if (ret) {
+               kfree(tbl);
+               return ret;
+       }
+
+       clp->cl_slot_tbl = tbl;
+       return 0;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+
+/**
+ * nfs41_init_client - nfs_client initialization tasks for NFSv4.1+
+ * @clp - nfs_client to initialize
+ *
+ * Returns zero on success, or a negative errno if some error occurred.
+ */
+int nfs41_init_client(struct nfs_client *clp)
+{
+       struct nfs4_session *session = NULL;
+
+       /*
+        * Create the session and mark it expired.
+        * When a SEQUENCE operation encounters the expired session
+        * it will do session recovery to initialize it.
+        */
+       session = nfs4_alloc_session(clp);
+       if (!session)
+               return -ENOMEM;
+
+       clp->cl_session = session;
+
+       /*
+        * The create session reply races with the server back
+        * channel probe. Mark the client NFS_CS_SESSION_INITING
+        * so that the client back channel can find the
+        * nfs_client struct
+        */
+       nfs_mark_client_ready(clp, NFS_CS_SESSION_INITING);
+       return 0;
+}
+
+#endif /* CONFIG_NFS_V4_1 */
+
+/*
+ * Initialize the minor version specific parts of an NFS4 client record
+ */
+static int nfs4_init_client_minor_version(struct nfs_client *clp)
+{
+       int ret;
+
+       ret = clp->cl_mvops->init_client(clp);
+       if (ret)
+               return ret;
+       return nfs4_init_callback(clp);
+}
+
+/**
+ * nfs4_init_client - Initialise an NFS4 client record
+ *
+ * @clp: nfs_client to initialise
+ * @timeparms: timeout parameters for underlying RPC transport
+ * @ip_addr: callback IP address in presentation format
+ * @authflavor: authentication flavor for underlying RPC transport
+ *
+ * Returns pointer to an NFS client, or an ERR_PTR value.
+ */
+struct nfs_client *nfs4_init_client(struct nfs_client *clp,
+                                   const struct rpc_timeout *timeparms,
+                                   const char *ip_addr)
+{
+       char buf[INET6_ADDRSTRLEN + 1];
+       struct nfs_client *old;
+       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 clp;
+       }
+
+       /* Check NFS protocol revision and initialize RPC op vector */
+       clp->rpc_ops = &nfs_v4_clientops;
+
+       if (clp->cl_minorversion != 0)
+               __set_bit(NFS_CS_INFINITE_SLOTS, &clp->cl_flags);
+       __set_bit(NFS_CS_DISCRTRY, &clp->cl_flags);
+       __set_bit(NFS_CS_NO_RETRANS_TIMEOUT, &clp->cl_flags);
+
+       error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_GSS_KRB5I);
+       if (error == -EINVAL)
+               error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_UNIX);
+       if (error < 0)
+               goto error;
+
+       /* If no clientaddr= option was specified, find a usable cb address */
+       if (ip_addr == NULL) {
+               struct sockaddr_storage cb_addr;
+               struct sockaddr *sap = (struct sockaddr *)&cb_addr;
+
+               error = rpc_localaddr(clp->cl_rpcclient, sap, sizeof(cb_addr));
+               if (error < 0)
+                       goto error;
+               error = rpc_ntop(sap, buf, sizeof(buf));
+               if (error < 0)
+                       goto error;
+               ip_addr = (const char *)buf;
+       }
+       strlcpy(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);
+
+       error = nfs4_init_client_minor_version(clp);
+       if (error < 0)
+               goto error;
+
+       if (!nfs4_has_session(clp))
+               nfs_mark_client_ready(clp, NFS_CS_READY);
+
+       error = nfs4_discover_server_trunking(clp, &old);
+       if (error < 0)
+               goto error;
+
+       if (clp != old)
+               clp->cl_preserve_clid = true;
+       nfs_put_client(clp);
+       return old;
+
+error:
+       nfs_mark_client_ready(clp, error);
+       nfs_put_client(clp);
+       dprintk("<-- nfs4_init_client() = xerror %d\n", error);
+       return ERR_PTR(error);
+}
+
+/*
+ * SETCLIENTID just did a callback update with the callback ident in
+ * "drop," but server trunking discovery claims "drop" and "keep" are
+ * actually the same server.  Swap the callback IDs so that "keep"
+ * will continue to use the callback ident the server now knows about,
+ * and so that "keep"'s original callback ident is destroyed when
+ * "drop" is freed.
+ */
+static void nfs4_swap_callback_idents(struct nfs_client *keep,
+                                     struct nfs_client *drop)
+{
+       struct nfs_net *nn = net_generic(keep->cl_net, nfs_net_id);
+       unsigned int save = keep->cl_cb_ident;
+
+       if (keep->cl_cb_ident == drop->cl_cb_ident)
+               return;
+
+       dprintk("%s: keeping callback ident %u and dropping ident %u\n",
+               __func__, keep->cl_cb_ident, drop->cl_cb_ident);
+
+       spin_lock(&nn->nfs_client_lock);
+
+       idr_replace(&nn->cb_ident_idr, keep, drop->cl_cb_ident);
+       keep->cl_cb_ident = drop->cl_cb_ident;
+
+       idr_replace(&nn->cb_ident_idr, drop, save);
+       drop->cl_cb_ident = save;
+
+       spin_unlock(&nn->nfs_client_lock);
+}
+
+static bool nfs4_match_client_owner_id(const struct nfs_client *clp1,
+               const struct nfs_client *clp2)
+{
+       if (clp1->cl_owner_id == NULL || clp2->cl_owner_id == NULL)
+               return true;
+       return strcmp(clp1->cl_owner_id, clp2->cl_owner_id) == 0;
+}
+
+/**
+ * nfs40_walk_client_list - Find server that recognizes a client ID
+ *
+ * @new: nfs_client with client ID to test
+ * @result: OUT: found nfs_client, or new
+ * @cred: credential to use for trunking test
+ *
+ * Returns zero, a negative errno, or a negative NFS4ERR status.
+ * If zero is returned, an nfs_client pointer is planted in "result."
+ *
+ * NB: nfs40_walk_client_list() relies on the new nfs_client being
+ *     the last nfs_client on the list.
+ */
+int nfs40_walk_client_list(struct nfs_client *new,
+                          struct nfs_client **result,
+                          struct rpc_cred *cred)
+{
+       struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
+       struct nfs_client *pos, *prev = NULL;
+       struct nfs4_setclientid_res clid = {
+               .clientid       = new->cl_clientid,
+               .confirm        = new->cl_confirm,
+       };
+       int status = -NFS4ERR_STALE_CLIENTID;
+
+       spin_lock(&nn->nfs_client_lock);
+       list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+               if (pos->rpc_ops != new->rpc_ops)
+                       continue;
+
+               if (pos->cl_minorversion != new->cl_minorversion)
+                       continue;
+
+               /* If "pos" isn't marked ready, we can't trust the
+                * remaining fields in "pos" */
+               if (pos->cl_cons_state > NFS_CS_READY) {
+                       atomic_inc(&pos->cl_count);
+                       spin_unlock(&nn->nfs_client_lock);
+
+                       nfs_put_client(prev);
+                       prev = pos;
+
+                       status = nfs_wait_client_init_complete(pos);
+                       if (status < 0)
+                               goto out;
+                       status = -NFS4ERR_STALE_CLIENTID;
+                       spin_lock(&nn->nfs_client_lock);
+               }
+               if (pos->cl_cons_state != NFS_CS_READY)
+                       continue;
+
+               if (pos->cl_clientid != new->cl_clientid)
+                       continue;
+
+               if (!nfs4_match_client_owner_id(pos, new))
+                       continue;
+
+               atomic_inc(&pos->cl_count);
+               spin_unlock(&nn->nfs_client_lock);
+
+               nfs_put_client(prev);
+               prev = pos;
+
+               status = nfs4_proc_setclientid_confirm(pos, &clid, cred);
+               switch (status) {
+               case -NFS4ERR_STALE_CLIENTID:
+                       break;
+               case 0:
+                       nfs4_swap_callback_idents(pos, new);
+
+                       prev = NULL;
+                       *result = pos;
+                       dprintk("NFS: <-- %s using nfs_client = %p ({%d})\n",
+                               __func__, pos, atomic_read(&pos->cl_count));
+                       goto out;
+               case -ERESTARTSYS:
+               case -ETIMEDOUT:
+                       /* The callback path may have been inadvertently
+                        * changed. Schedule recovery!
+                        */
+                       nfs4_schedule_path_down_recovery(pos);
+               default:
+                       goto out;
+               }
+
+               spin_lock(&nn->nfs_client_lock);
+       }
+       spin_unlock(&nn->nfs_client_lock);
+
+       /* No match found. The server lost our clientid */
+out:
+       nfs_put_client(prev);
+       dprintk("NFS: <-- %s status = %d\n", __func__, status);
+       return status;
+}
+
+#ifdef CONFIG_NFS_V4_1
+/*
+ * Returns true if the client IDs match
+ */
+static bool nfs4_match_clientids(struct nfs_client *a, struct nfs_client *b)
+{
+       if (a->cl_clientid != b->cl_clientid) {
+               dprintk("NFS: --> %s client ID %llx does not match %llx\n",
+                       __func__, a->cl_clientid, b->cl_clientid);
+               return false;
+       }
+       dprintk("NFS: --> %s client ID %llx matches %llx\n",
+               __func__, a->cl_clientid, b->cl_clientid);
+       return true;
+}
+
+/*
+ * Returns true if the server major ids match
+ */
+static bool
+nfs4_check_clientid_trunking(struct nfs_client *a, struct nfs_client *b)
+{
+       struct nfs41_server_owner *o1 = a->cl_serverowner;
+       struct nfs41_server_owner *o2 = b->cl_serverowner;
+
+       if (o1->major_id_sz != o2->major_id_sz)
+               goto out_major_mismatch;
+       if (memcmp(o1->major_id, o2->major_id, o1->major_id_sz) != 0)
+               goto out_major_mismatch;
+
+       dprintk("NFS: --> %s server owners match\n", __func__);
+       return true;
+
+out_major_mismatch:
+       dprintk("NFS: --> %s server owner major IDs do not match\n",
+               __func__);
+       return false;
+}
+
+/**
+ * nfs41_walk_client_list - Find nfs_client that matches a client/server owner
+ *
+ * @new: nfs_client with client ID to test
+ * @result: OUT: found nfs_client, or new
+ * @cred: credential to use for trunking test
+ *
+ * Returns zero, a negative errno, or a negative NFS4ERR status.
+ * If zero is returned, an nfs_client pointer is planted in "result."
+ *
+ * NB: nfs41_walk_client_list() relies on the new nfs_client being
+ *     the last nfs_client on the list.
+ */
+int nfs41_walk_client_list(struct nfs_client *new,
+                          struct nfs_client **result,
+                          struct rpc_cred *cred)
+{
+       struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
+       struct nfs_client *pos, *prev = NULL;
+       int status = -NFS4ERR_STALE_CLIENTID;
+
+       spin_lock(&nn->nfs_client_lock);
+       list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+               if (pos == new)
+                       goto found;
+
+               if (pos->rpc_ops != new->rpc_ops)
+                       continue;
+
+               if (pos->cl_minorversion != new->cl_minorversion)
+                       continue;
+
+               /* If "pos" isn't marked ready, we can't trust the
+                * remaining fields in "pos", especially the client
+                * ID and serverowner fields.  Wait for CREATE_SESSION
+                * to finish. */
+               if (pos->cl_cons_state > NFS_CS_READY) {
+                       atomic_inc(&pos->cl_count);
+                       spin_unlock(&nn->nfs_client_lock);
+
+                       nfs_put_client(prev);
+                       prev = pos;
+
+                       status = nfs_wait_client_init_complete(pos);
+                       spin_lock(&nn->nfs_client_lock);
+                       if (status < 0)
+                               break;
+                       status = -NFS4ERR_STALE_CLIENTID;
+               }
+               if (pos->cl_cons_state != NFS_CS_READY)
+                       continue;
+
+               if (!nfs4_match_clientids(pos, new))
+                       continue;
+
+               /*
+                * Note that session trunking is just a special subcase of
+                * client id trunking. In either case, we want to fall back
+                * to using the existing nfs_client.
+                */
+               if (!nfs4_check_clientid_trunking(pos, new))
+                       continue;
+
+               /* Unlike NFSv4.0, we know that NFSv4.1 always uses the
+                * uniform string, however someone might switch the
+                * uniquifier string on us.
+                */
+               if (!nfs4_match_client_owner_id(pos, new))
+                       continue;
+found:
+               atomic_inc(&pos->cl_count);
+               *result = pos;
+               status = 0;
+               dprintk("NFS: <-- %s using nfs_client = %p ({%d})\n",
+                       __func__, pos, atomic_read(&pos->cl_count));
+               break;
+       }
+
+       /* No matching nfs_client found. */
+       spin_unlock(&nn->nfs_client_lock);
+       dprintk("NFS: <-- %s status = %d\n", __func__, status);
+       nfs_put_client(prev);
+       return status;
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+static void nfs4_destroy_server(struct nfs_server *server)
+{
+       nfs_server_return_all_delegations(server);
+       unset_pnfs_layoutdriver(server);
+       nfs4_purge_state_owners(server);
+}
+
+/*
+ * NFSv4.0 callback thread helper
+ *
+ * Find a client by callback identifier
+ */
+struct nfs_client *
+nfs4_find_client_ident(struct net *net, int cb_ident)
+{
+       struct nfs_client *clp;
+       struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+       spin_lock(&nn->nfs_client_lock);
+       clp = idr_find(&nn->cb_ident_idr, cb_ident);
+       if (clp)
+               atomic_inc(&clp->cl_count);
+       spin_unlock(&nn->nfs_client_lock);
+       return clp;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+/* Common match routine for v4.0 and v4.1 callback services */
+static bool nfs4_cb_match_client(const struct sockaddr *addr,
+               struct nfs_client *clp, u32 minorversion)
+{
+       struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
+
+       /* Don't match clients that failed to initialise */
+       if (!(clp->cl_cons_state == NFS_CS_READY ||
+           clp->cl_cons_state == NFS_CS_SESSION_INITING))
+               return false;
+
+       smp_rmb();
+
+       /* Match the version and minorversion */
+       if (clp->rpc_ops->version != 4 ||
+           clp->cl_minorversion != minorversion)
+               return false;
+
+       /* Match only the IP address, not the port number */
+       if (!nfs_sockaddr_match_ipaddr(addr, clap))
+               return false;
+
+       return true;
+}
+
+/*
+ * NFSv4.1 callback thread helper
+ * For CB_COMPOUND calls, find a client by IP address, protocol version,
+ * minorversion, and sessionID
+ *
+ * Returns NULL if no such client
+ */
+struct nfs_client *
+nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
+                          struct nfs4_sessionid *sid, u32 minorversion)
+{
+       struct nfs_client *clp;
+       struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+       spin_lock(&nn->nfs_client_lock);
+       list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
+               if (nfs4_cb_match_client(addr, clp, minorversion) == false)
+                       continue;
+
+               if (!nfs4_has_session(clp))
+                       continue;
+
+               /* Match sessionid*/
+               if (memcmp(clp->cl_session->sess_id.data,
+                   sid->data, NFS4_MAX_SESSIONID_LEN) != 0)
+                       continue;
+
+               atomic_inc(&clp->cl_count);
+               spin_unlock(&nn->nfs_client_lock);
+               return clp;
+       }
+       spin_unlock(&nn->nfs_client_lock);
+       return NULL;
+}
+
+#else /* CONFIG_NFS_V4_1 */
+
+struct nfs_client *
+nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
+                          struct nfs4_sessionid *sid, u32 minorversion)
+{
+       return NULL;
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+/*
+ * 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,
+               u32 minorversion, struct net *net)
+{
+       struct nfs_client_initdata cl_init = {
+               .hostname = hostname,
+               .addr = addr,
+               .addrlen = addrlen,
+               .nfs_mod = &nfs_v4,
+               .proto = proto,
+               .minorversion = minorversion,
+               .net = net,
+       };
+       struct nfs_client *clp;
+       int error;
+
+       dprintk("--> nfs4_set_client()\n");
+
+       if (server->flags & NFS_MOUNT_NORESVPORT)
+               set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
+       if (server->options & NFS_OPTION_MIGRATION)
+               set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);
+
+       /* Allocate or find a client reference we can use */
+       clp = nfs_get_client(&cl_init, timeparms, ip_addr, authflavour);
+       if (IS_ERR(clp)) {
+               error = PTR_ERR(clp);
+               goto error;
+       }
+
+       /*
+        * Query for the lease time on clientid setup or renewal
+        *
+        * Note that this will be set on nfs_clients that were created
+        * only for the DS role and did not set this bit, but now will
+        * serve a dual role.
+        */
+       set_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state);
+
+       server->nfs_client = clp;
+       dprintk("<-- nfs4_set_client() = 0 [new %p]\n", clp);
+       return 0;
+error:
+       dprintk("<-- nfs4_set_client() = xerror %d\n", error);
+       return error;
+}
+
+/*
+ * Set up a pNFS Data Server client.
+ *
+ * Return any existing nfs_client that matches server address,port,version
+ * and minorversion.
+ *
+ * For a new nfs_client, use a soft mount (default), a low retrans and a
+ * low timeout interval so that if a connection is lost, we retry through
+ * the MDS.
+ */
+struct nfs_client *nfs4_set_ds_client(struct nfs_client* mds_clp,
+               const struct sockaddr *ds_addr, int ds_addrlen,
+               int ds_proto, unsigned int ds_timeo, unsigned int ds_retrans,
+               u32 minor_version, rpc_authflavor_t au_flavor)
+{
+       struct nfs_client_initdata cl_init = {
+               .addr = ds_addr,
+               .addrlen = ds_addrlen,
+               .nfs_mod = &nfs_v4,
+               .proto = ds_proto,
+               .minorversion = minor_version,
+               .net = mds_clp->cl_net,
+       };
+       struct rpc_timeout ds_timeout;
+       struct nfs_client *clp;
+       char buf[INET6_ADDRSTRLEN + 1];
+
+       if (rpc_ntop(ds_addr, buf, sizeof(buf)) <= 0)
+               return ERR_PTR(-EINVAL);
+       cl_init.hostname = buf;
+
+       /*
+        * Set an authflavor equual to the MDS value. Use the MDS nfs_client
+        * cl_ipaddr so as to use the same EXCHANGE_ID co_ownerid as the MDS
+        * (section 13.1 RFC 5661).
+        */
+       nfs_init_timeout_values(&ds_timeout, ds_proto, ds_timeo, ds_retrans);
+       clp = nfs_get_client(&cl_init, &ds_timeout, mds_clp->cl_ipaddr,
+                            au_flavor);
+
+       dprintk("<-- %s %p\n", __func__, clp);
+       return clp;
+}
+EXPORT_SYMBOL_GPL(nfs4_set_ds_client);
+
+/*
+ * Session has been established, and the client marked ready.
+ * Set the mount rsize and wsize with negotiated fore channel
+ * attributes which will be bound checked in nfs_server_set_fsinfo.
+ */
+static void nfs4_session_set_rwsize(struct nfs_server *server)
+{
+#ifdef CONFIG_NFS_V4_1
+       struct nfs4_session *sess;
+       u32 server_resp_sz;
+       u32 server_rqst_sz;
+
+       if (!nfs4_has_session(server->nfs_client))
+               return;
+       sess = server->nfs_client->cl_session;
+       server_resp_sz = sess->fc_attrs.max_resp_sz - nfs41_maxread_overhead;
+       server_rqst_sz = sess->fc_attrs.max_rqst_sz - nfs41_maxwrite_overhead;
+
+       if (server->rsize > server_resp_sz)
+               server->rsize = server_resp_sz;
+       if (server->wsize > server_rqst_sz)
+               server->wsize = server_rqst_sz;
+#endif /* CONFIG_NFS_V4_1 */
+}
+
+static int nfs4_server_common_setup(struct nfs_server *server,
+               struct nfs_fh *mntfh, bool auth_probe)
+{
+       struct nfs_fattr *fattr;
+       int error;
+
+       /* data servers support only a subset of NFSv4.1 */
+       if (is_ds_only_client(server->nfs_client))
+               return -EPROTONOSUPPORT;
+
+       fattr = nfs_alloc_fattr();
+       if (fattr == NULL)
+               return -ENOMEM;
+
+       /* We must ensure the session is initialised first */
+       error = nfs4_init_session(server->nfs_client);
+       if (error < 0)
+               goto out;
+
+       /* Set the basic capabilities */
+       server->caps |= server->nfs_client->cl_mvops->init_caps;
+       if (server->flags & NFS_MOUNT_NORDIRPLUS)
+                       server->caps &= ~NFS_CAP_READDIRPLUS;
+       /*
+        * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
+        * authentication.
+        */
+       if (nfs4_disable_idmapping &&
+                       server->client->cl_auth->au_flavor == RPC_AUTH_UNIX)
+               server->caps |= NFS_CAP_UIDGID_NOMAP;
+
+
+       /* Probe the root fh to retrieve its FSID and filehandle */
+       error = nfs4_get_rootfh(server, mntfh, auth_probe);
+       if (error < 0)
+               goto out;
+
+       dprintk("Server FSID: %llx:%llx\n",
+                       (unsigned long long) server->fsid.major,
+                       (unsigned long long) server->fsid.minor);
+       nfs_display_fhandle(mntfh, "Pseudo-fs root FH");
+
+       nfs4_session_set_rwsize(server);
+
+       error = nfs_probe_fsinfo(server, mntfh, fattr);
+       if (error < 0)
+               goto out;
+
+       if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
+               server->namelen = NFS4_MAXNAMLEN;
+
+       nfs_server_insert_lists(server);
+       server->mount_time = jiffies;
+       server->destroy = nfs4_destroy_server;
+out:
+       nfs_free_fattr(fattr);
+       return error;
+}
+
+/*
+ * Create a version 4 volume record
+ */
+static int nfs4_init_server(struct nfs_server *server,
+               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);
+
+       /* Initialise the client representation from the mount data */
+       server->flags = data->flags;
+       server->options = data->options;
+       server->auth_info = data->auth_info;
+
+       /* Use the first specified auth flavor. If this flavor isn't
+        * allowed by the server, use the SECINFO path to try the
+        * other specified flavors */
+       if (data->auth_info.flavor_len >= 1)
+               data->selected_flavor = data->auth_info.flavors[0];
+       else
+               data->selected_flavor = RPC_AUTH_UNIX;
+
+       /* 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->selected_flavor,
+                       data->nfs_server.protocol,
+                       &timeparms,
+                       data->minorversion,
+                       data->net);
+       if (error < 0)
+               goto error;
+
+       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->selected_flavor);
+
+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_server *nfs4_create_server(struct nfs_mount_info *mount_info,
+                                     struct nfs_subversion *nfs_mod)
+{
+       struct nfs_server *server;
+       bool auth_probe;
+       int error;
+
+       dprintk("--> nfs4_create_server()\n");
+
+       server = nfs_alloc_server();
+       if (!server)
+               return ERR_PTR(-ENOMEM);
+
+       auth_probe = mount_info->parsed->auth_info.flavor_len < 1;
+
+       /* set up the general RPC client */
+       error = nfs4_init_server(server, mount_info->parsed);
+       if (error < 0)
+               goto error;
+
+       error = nfs4_server_common_setup(server, mount_info->mntfh, auth_probe);
+       if (error < 0)
+               goto error;
+
+       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;
+       bool auth_probe;
+       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;
+
+       /* Initialise the client representation from the parent server */
+       nfs_server_copy_userdata(server, parent_server);
+
+       /* 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,
+                               rpc_protocol(parent_server->client),
+                               parent_server->client->cl_timeout,
+                               parent_client->cl_mvops->minor_version,
+                               parent_client->cl_net);
+       if (error < 0)
+               goto error;
+
+       error = nfs_init_server_rpcclient(server, parent_server->client->cl_timeout, data->authflavor);
+       if (error < 0)
+               goto error;
+
+       auth_probe = parent_server->auth_info.flavor_len < 1;
+
+       error = nfs4_server_common_setup(server, mntfh, auth_probe);
+       if (error < 0)
+               goto error;
+
+       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);
+}
+
+/*
+ * Grab the destination's particulars, including lease expiry time.
+ *
+ * Returns zero if probe succeeded and retrieved FSID matches the FSID
+ * we have cached.
+ */
+static int nfs_probe_destination(struct nfs_server *server)
+{
+       struct inode *inode = d_inode(server->super->s_root);
+       struct nfs_fattr *fattr;
+       int error;
+
+       fattr = nfs_alloc_fattr();
+       if (fattr == NULL)
+               return -ENOMEM;
+
+       /* Sanity: the probe won't work if the destination server
+        * does not recognize the migrated FH. */
+       error = nfs_probe_fsinfo(server, NFS_FH(inode), fattr);
+
+       nfs_free_fattr(fattr);
+       return error;
+}
+
+/**
+ * nfs4_update_server - Move an nfs_server to a different nfs_client
+ *
+ * @server: represents FSID to be moved
+ * @hostname: new end-point's hostname
+ * @sap: new end-point's socket address
+ * @salen: size of "sap"
+ * @net: net namespace
+ *
+ * The nfs_server must be quiescent before this function is invoked.
+ * Either its session is drained (NFSv4.1+), or its transport is
+ * plugged and drained (NFSv4.0).
+ *
+ * Returns zero on success, or a negative errno value.
+ */
+int nfs4_update_server(struct nfs_server *server, const char *hostname,
+                      struct sockaddr *sap, size_t salen, struct net *net)
+{
+       struct nfs_client *clp = server->nfs_client;
+       struct rpc_clnt *clnt = server->client;
+       struct xprt_create xargs = {
+               .ident          = clp->cl_proto,
+               .net            = net,
+               .dstaddr        = sap,
+               .addrlen        = salen,
+               .servername     = hostname,
+       };
+       char buf[INET6_ADDRSTRLEN + 1];
+       struct sockaddr_storage address;
+       struct sockaddr *localaddr = (struct sockaddr *)&address;
+       int error;
+
+       dprintk("--> %s: move FSID %llx:%llx to \"%s\")\n", __func__,
+                       (unsigned long long)server->fsid.major,
+                       (unsigned long long)server->fsid.minor,
+                       hostname);
+
+       error = rpc_switch_client_transport(clnt, &xargs, clnt->cl_timeout);
+       if (error != 0) {
+               dprintk("<-- %s(): rpc_switch_client_transport returned %d\n",
+                       __func__, error);
+               goto out;
+       }
+
+       error = rpc_localaddr(clnt, localaddr, sizeof(address));
+       if (error != 0) {
+               dprintk("<-- %s(): rpc_localaddr returned %d\n",
+                       __func__, error);
+               goto out;
+       }
+
+       error = -EAFNOSUPPORT;
+       if (rpc_ntop(localaddr, buf, sizeof(buf)) == 0) {
+               dprintk("<-- %s(): rpc_ntop returned %d\n",
+                       __func__, error);
+               goto out;
+       }
+
+       nfs_server_remove_lists(server);
+       error = nfs4_set_client(server, hostname, sap, salen, buf,
+                               clp->cl_rpcclient->cl_auth->au_flavor,
+                               clp->cl_proto, clnt->cl_timeout,
+                               clp->cl_minorversion, net);
+       nfs_put_client(clp);
+       if (error != 0) {
+               nfs_server_insert_lists(server);
+               dprintk("<-- %s(): nfs4_set_client returned %d\n",
+                       __func__, error);
+               goto out;
+       }
+
+       if (server->nfs_client->cl_hostname == NULL)
+               server->nfs_client->cl_hostname = kstrdup(hostname, GFP_KERNEL);
+       nfs_server_insert_lists(server);
+
+       error = nfs_probe_destination(server);
+       if (error < 0)
+               goto out;
+
+       dprintk("<-- %s() succeeded\n", __func__);
+
+out:
+       return error;
+}