The NFSv4 state model assumes that the client machine identifies

itself to the server once and once only.
This patch ensures that we do this by sharing the local identifier
struct nfs4_client among all mountpoints that talk to the same
server/ip address.

fs/nfs/nfs4proc.c

@@ -740,6 +740,7 @@ static int
 nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 		   struct nfs_fattr *fattr)
 {
+	struct nfs4_client	*clp;
 	struct nfs4_compound	compound;
 	struct nfs4_op		ops[4];
 	struct nfs_fsinfo	fsinfo;
@@ -747,11 +748,24 @@ nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 	struct qstr		q;
 	int			status;
 
-	fattr->valid = 0;
-
-	if (!(server->nfs4_state = nfs4_get_client()))
+	clp = server->nfs4_state = nfs4_get_client(&server->addr.sin_addr);
+	if (!clp)
 		return -ENOMEM;
 
+	down_write(&clp->cl_sem);
+	/* Has the clientid already been initialized? */
+	if (clp->cl_state != NFS4CLNT_NEW) {
+		/* Yep, so just read the root attributes and the lease time. */
+		fattr->valid = 0;
+		nfs4_setup_compound(&compound, ops, server, "getrootfh");
+		nfs4_setup_putrootfh(&compound);
+		nfs4_setup_getrootattr(&compound, fattr, &fsinfo);
+		nfs4_setup_getfh(&compound, fhandle);
+		if ((status = nfs4_call_compound(&compound, NULL, 0)))
+			goto out_unlock;
+		goto no_setclientid;
+	}
+
 	/* 
 	 * SETCLIENTID.
 	 * Until delegations are imported, we don't bother setting the program
@@ -760,28 +774,33 @@ nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 	nfs4_setup_compound(&compound, ops, server, "setclientid");
 	nfs4_setup_setclientid(&compound, 0, 0);
 	if ((status = nfs4_call_compound(&compound, NULL, 0)))
-		goto out;
+		goto out_unlock;
 
 	/*
 	 * SETCLIENTID_CONFIRM, plus root filehandle.
 	 * We also get the lease time here.
 	 */
+	fattr->valid = 0;
 	nfs4_setup_compound(&compound, ops, server, "setclientid_confirm");
 	nfs4_setup_setclientid_confirm(&compound);
 	nfs4_setup_putrootfh(&compound);
 	nfs4_setup_getrootattr(&compound, fattr, &fsinfo);
 	nfs4_setup_getfh(&compound, fhandle);
 	if ((status = nfs4_call_compound(&compound, NULL, 0)))
-		goto out;
-	
+		goto out_unlock;
+	clp->cl_state = NFS4CLNT_OK;
+
+no_setclientid:
 	/*
 	 * Now that we have instantiated the clientid and determined
 	 * the lease time, we can initialize the renew daemon for this
 	 * server.
+	 * FIXME: we only need one renewd daemon per server.
 	 */
 	server->lease_time = fsinfo.lease_time * HZ;
 	if ((status = nfs4_init_renewd(server)))
-		goto out;
+		goto out_unlock;
+	up_write(&clp->cl_sem);
 	
 	/*
 	 * Now we do a separate LOOKUP for each component of the mount path.
@@ -799,6 +818,7 @@ nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 			p++;
 		q.len = p - q.name;
 
+		fattr->valid = 0;
 		nfs4_setup_compound(&compound, ops, server, "mount");
 		nfs4_setup_putfh(&compound, fhandle);
 		nfs4_setup_lookup(&compound, &q);
@@ -813,8 +833,11 @@ nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 		}
 		break;
 	}
-
-out:
+	return status;
+out_unlock:
+	up_write(&clp->cl_sem);
+	nfs4_put_client(clp);
+	server->nfs4_state = NULL;
 	return status;
 }
 

fs/nfs/nfs4state.c

@@ -51,6 +51,7 @@ nfs4_stateid zero_stateid =
 nfs4_stateid one_stateid =
 	{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
+static LIST_HEAD(nfs4_clientid_list);
 
 /*
  * nfs4_get_client(): returns an empty client structure
@@ -60,22 +61,62 @@ nfs4_stateid one_stateid =
  * bother putting them in a slab cache...
  */
 struct nfs4_client *
-nfs4_get_client(void)
+nfs4_alloc_client(struct in_addr *addr)
 {
 	struct nfs4_client *clp;
 
-	if ((clp = kmalloc(sizeof(*clp), GFP_KERNEL)))
+	if ((clp = kmalloc(sizeof(*clp), GFP_KERNEL))) {
 		memset(clp, 0, sizeof(*clp));
+		memcpy(&clp->cl_addr, addr, sizeof(clp->cl_addr));
+		init_rwsem(&clp->cl_sem);
+		INIT_LIST_HEAD(&clp->cl_state_owners);
+		spin_lock_init(&clp->cl_lock);
+		atomic_set(&clp->cl_count, 1);
+		clp->cl_state = NFS4CLNT_NEW;
+	}
 	return clp;
 }
 
 void
-nfs4_put_client(struct nfs4_client *clp)
+nfs4_free_client(struct nfs4_client *clp)
 {
 	BUG_ON(!clp);
 	kfree(clp);
 }
 
+struct nfs4_client *
+nfs4_get_client(struct in_addr *addr)
+{
+	struct nfs4_client *new, *clp = NULL;
+
+	new = nfs4_alloc_client(addr);
+	spin_lock(&state_spinlock);
+	list_for_each_entry(clp, &nfs4_clientid_list, cl_servers) {
+		if (memcmp(&clp->cl_addr, addr, sizeof(clp->cl_addr)) == 0)
+			goto found;
+	}
+	if (new)
+		list_add(&new->cl_servers, &nfs4_clientid_list);
+	spin_unlock(&state_spinlock);
+	return new;
+found:
+	atomic_inc(&clp->cl_count);
+	spin_unlock(&state_spinlock);
+	if (new)
+		nfs4_free_client(new);
+	return clp;
+}
+
+void
+nfs4_put_client(struct nfs4_client *clp)
+{
+	if (!atomic_dec_and_lock(&clp->cl_count, &state_spinlock))
+		return;
+	list_del(&clp->cl_servers);
+	spin_unlock(&state_spinlock);
+	nfs4_free_client(clp);
+}
+
 static inline u32
 nfs4_alloc_lockowner_id(struct nfs4_client *clp)
 {

include/linux/nfs_fs.h

@@ -13,6 +13,7 @@
 #include <linux/in.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
+#include <linux/rwsem.h>
 #include <linux/wait.h>
 #include <linux/uio.h>
 
@@ -469,11 +470,32 @@ extern void * nfs_root_data(void);
  ((err) != NFSERR_RESOURCE)       &&  \
  ((err) != NFSERR_NOFILEHANDLE))
 
+enum nfs4_client_state {
+	NFS4CLNT_OK  = 0,
+	NFS4CLNT_NEW,
+};
+
+/*
+ * The nfs4_client identifies our client state to the server.
+ */
 struct nfs4_client {
-        u64                     cl_clientid;    /* constant */
-	nfs4_verifier           cl_confirm;     
+	struct list_head	cl_servers;	/* Global list of servers */
+	struct in_addr		cl_addr;	/* Server identifier */
+	u64			cl_clientid;	/* constant */
+	nfs4_verifier		cl_confirm;
+	enum nfs4_client_state	cl_state;
 
 	u32			cl_lockowner_id;
+
+	/*
+	 * The following rwsem ensures exclusive access to the server
+	 * while we recover the state following a lease expiration.
+	 */
+	struct rw_semaphore	cl_sem;
+
+	struct list_head	cl_state_owners;
+	spinlock_t		cl_lock;
+	atomic_t		cl_count;
 };
 
 /*
@@ -483,6 +505,7 @@ struct nfs4_client {
 * the protocol.
 */
 struct nfs4_state_owner {
+	struct list_head     so_list;	 /* per-clientid list of state_owners */
 	u32                  so_id;      /* 32-bit identifier, unique */
 	struct semaphore     so_sema;
 	u32                  so_seqid;   /* protected by so_sema */
@@ -499,7 +522,7 @@ extern int nfs4_do_close(struct inode *inode, struct nfs4_state_owner *sp);
 extern int nfs4_init_renewd(struct nfs_server *server);
 
 /* nfs4state.c */
-extern struct nfs4_client *nfs4_get_client(void);
+extern struct nfs4_client *nfs4_get_client(struct in_addr *);
 extern void nfs4_put_client(struct nfs4_client *clp);
 extern struct nfs4_state_owner * nfs4_get_state_owner(struct inode *inode);
 void nfs4_put_state_owner(struct inode *inode, struct nfs4_state_owner *sp);