NFSv4.1: Handle EXCHGID4_FLAG_CONFIRMED_R during NFSv4.1 migration

Transparent State Migration copies a client's lease state from the
server where a filesystem used to reside to the server where it now
resides. When an NFSv4.1 client first contacts that destination
server, it uses EXCHANGE_ID to detect trunking relationships.

The lease that was copied there is returned to that client, but the
destination server sets EXCHGID4_FLAG_CONFIRMED_R when replying to
the client. This is because the lease was confirmed on the source
server (before it was copied).

Normally, when CONFIRMED_R is set, a client purges the lease and
creates a new one. However, that throws away the entire benefit of
Transparent State Migration.

Therefore, the client must not purge that lease when it is possible
that Transparent State Migration has occurred.

Reported-by: Xuan Qi <xuan.qi@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Xuan Qi <xuan.qi@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 66776f02211131bd003e31748dec6774a02a077f..50566acb54694ac4f14330f4bbb7ab360ba15f88 100644 (file)
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -414,6 +414,7 @@ struct nfs_client *nfs4_init_client(struct nfs_client *clp,
        if (clp != old)
                clp->cl_preserve_clid = true;
        nfs_put_client(clp);
+       clear_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags);
        return old;
 
 error:
@@ -852,6 +853,8 @@ static int nfs4_set_client(struct nfs_server *server,
                set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
        if (server->options & NFS_OPTION_MIGRATION)
                set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);
+       if (test_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status))
+               set_bit(NFS_CS_TSM_POSSIBLE, &cl_init.init_flags);
 
        /* Allocate or find a client reference we can use */
        clp = nfs_get_client(&cl_init);
@@ -1212,9 +1215,11 @@ int nfs4_update_server(struct nfs_server *server, const char *hostname,
                return -EAFNOSUPPORT;
 
        nfs_server_remove_lists(server);
+       set_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status);
        error = nfs4_set_client(server, hostname, sap, salen, buf,
                                clp->cl_proto, clnt->cl_timeout,
                                clp->cl_minorversion, net);
+       clear_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status);
        nfs_put_client(clp);
        if (error != 0) {
                nfs_server_insert_lists(server);

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index b34de036501bc90e48be043aec38485f7f755e55..83f8e60bb1e3f78a4765b22a54450ffbf904ca09 100644 (file)
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -352,11 +352,17 @@ int nfs41_discover_server_trunking(struct nfs_client *clp,
        if (clp != *result)
                return 0;
 
-       /* Purge state if the client id was established in a prior instance */
-       if (clp->cl_exchange_flags & EXCHGID4_FLAG_CONFIRMED_R)
-               set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
-       else
-               set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+       /*
+        * Purge state if the client id was established in a prior
+        * instance and the client id could not have arrived on the
+        * server via Transparent State Migration.
+        */
+       if (clp->cl_exchange_flags & EXCHGID4_FLAG_CONFIRMED_R) {
+               if (!test_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags))
+                       set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
+               else
+                       set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+       }
        nfs4_schedule_state_manager(clp);
        status = nfs_wait_client_init_complete(clp);
        if (status < 0)

diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index e418a1096662c387f1b96e834d90983c22e5106f..74c44665e6d33dd4f7c8bfce30457eb56f942c80 100644 (file)
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -42,6 +42,7 @@ struct nfs_client {
 #define NFS_CS_MIGRATION       2               /* - transparent state migr */
 #define NFS_CS_INFINITE_SLOTS  3               /* - don't limit TCP slots */
 #define NFS_CS_NO_RETRANS_TIMEOUT      4       /* - Disable retransmit timeouts */
+#define NFS_CS_TSM_POSSIBLE    5               /* - Maybe state migration */
        struct sockaddr_storage cl_addr;        /* server identifier */
        size_t                  cl_addrlen;
        char *                  cl_hostname;    /* hostname of server */
@@ -210,6 +211,7 @@ struct nfs_server {
        unsigned long           mig_status;
 #define NFS_MIG_IN_TRANSITION          (1)
 #define NFS_MIG_FAILED                 (2)
+#define NFS_MIG_TSM_POSSIBLE           (3)
 
        void (*destroy)(struct nfs_server *);