NFS: Support NFS4ERR_LEASE_MOVED recovery in state manager

A migration on the FSID in play for the current NFS operation
is reported via the error status code NFS4ERR_MOVED.

"Lease moved" means that a migration has occurred on some other
FSID than the one for the current operation.  It's a signal that
the client should take action immediately to handle a migration
that it may not have noticed otherwise.  This is so that the
client's lease does not expire unnoticed on the destination server.

In NFSv4.0, a moved lease is reported with the NFS4ERR_LEASE_MOVED
error status code.

To recover from NFS4ERR_LEASE_MOVED, check each FSID for that server
to see if it is still present.  Invoke nfs4_try_migration() if the
FSID is no longer present on the server.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 74 insertions, 1 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 2f0f8c216441..210e44ed1d2a 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -30,6 +30,7 @@ enum nfs4_client_state {
         NFS4CLNT_PURGE_STATE,
         NFS4CLNT_BIND_CONN_TO_SESSION,
         NFS4CLNT_MOVED,
+        NFS4CLNT_LEASE_MOVED,
 };
 
 #define NFS4_RENEW_TIMEOUT              0x01
@@ -425,6 +426,7 @@ extern void nfs4_schedule_state_manager(struct nfs_client *);
 extern void nfs4_schedule_path_down_recovery(struct nfs_client *clp);
 extern int nfs4_schedule_stateid_recovery(const struct nfs_server *, struct nfs4_state *);
 extern int nfs4_schedule_migration_recovery(const struct nfs_server *);
+extern void nfs4_schedule_lease_moved_recovery(struct nfs_client *);
 extern void nfs41_handle_sequence_flag_errors(struct nfs_client *clp, u32 flags);
 extern void nfs41_handle_server_scope(struct nfs_client *,
                                       struct nfs41_server_scope **);
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index ba0db18b5f67..552706d2d776 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1233,6 +1233,22 @@ int nfs4_schedule_migration_recovery(const struct nfs_server *server)
 }
 EXPORT_SYMBOL_GPL(nfs4_schedule_migration_recovery);
 
+/**
+ * nfs4_schedule_lease_moved_recovery - start lease-moved recovery
+ *
+ * @clp: server to check for moved leases
+ *
+ */
+void nfs4_schedule_lease_moved_recovery(struct nfs_client *clp)
+{
+        dprintk("%s: scheduling lease-moved recovery for client ID %llx on %s\n",
+                __func__, clp->cl_clientid, clp->cl_hostname);
+
+        set_bit(NFS4CLNT_LEASE_MOVED, &clp->cl_state);
+        nfs4_schedule_state_manager(clp);
+}
+EXPORT_SYMBOL_GPL(nfs4_schedule_lease_moved_recovery);
+
 int nfs4_wait_clnt_recover(struct nfs_client *clp)
 {
         int res;
@@ -1661,7 +1677,6 @@ static int nfs4_recovery_handle_error(struct nfs_client *clp, int error)
                         nfs4_state_end_reclaim_reboot(clp);
                         break;
                 case -NFS4ERR_STALE_CLIENTID:
-                case -NFS4ERR_LEASE_MOVED:
                         set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                         nfs4_state_clear_reclaim_reboot(clp);
                         nfs4_state_start_reclaim_reboot(clp);
@@ -1975,6 +1990,55 @@ restart:
         return 0;
 }
 
+/*
+ * Test each nfs_server on the clp's cl_superblocks list to see
+ * if it's moved to another server.  Stop when the server no longer
+ * returns NFS4ERR_LEASE_MOVED.
+ */
+static int nfs4_handle_lease_moved(struct nfs_client *clp)
+{
+        const struct nfs4_state_maintenance_ops *ops =
+                                clp->cl_mvops->state_renewal_ops;
+        struct nfs_server *server;
+        struct rpc_cred *cred;
+
+        dprintk("%s: lease moved reported on \"%s\"\n", __func__,
+                        clp->cl_hostname);
+
+        spin_lock(&clp->cl_lock);
+        cred = ops->get_state_renewal_cred_locked(clp);
+        spin_unlock(&clp->cl_lock);
+        if (cred == NULL)
+                return -NFS4ERR_NOENT;
+
+        clp->cl_mig_gen++;
+restart:
+        rcu_read_lock();
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+                struct inode *inode;
+                int status;
+
+                if (server->mig_gen == clp->cl_mig_gen)
+                        continue;
+                server->mig_gen = clp->cl_mig_gen;
+
+                rcu_read_unlock();
+
+                inode = server->super->s_root->d_inode;
+                status = nfs4_proc_fsid_present(inode, cred);
+                if (status != -NFS4ERR_MOVED)
+                        goto restart;   /* wasn't this one */
+                if (nfs4_try_migration(server, cred) == -NFS4ERR_LEASE_MOVED)
+                        goto restart;   /* there are more */
+                goto out;
+        }
+        rcu_read_unlock();
+
+out:
+        put_rpccred(cred);
+        return 0;
+}
+
 /**
  * nfs4_discover_server_trunking - Detect server IP address trunking
  *
@@ -2312,6 +2376,13 @@ static void nfs4_state_manager(struct nfs_client *clp)
                                 goto out_error;
                 }
 
+                if (test_and_clear_bit(NFS4CLNT_LEASE_MOVED, &clp->cl_state)) {
+                        section = "lease moved";
+                        status = nfs4_handle_lease_moved(clp);
+                        if (status < 0)
+                                goto out_error;
+                }
+
                 /* First recover reboot state... */
                 if (test_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state)) {
                         section = "reclaim reboot";