6 files changed, 86 insertions, 16 deletions

diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index 25e8802a51d1..b678e3e15bd9 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -138,6 +138,8 @@ extern __be32 nfs4_callback_recallslot(struct cb_recallslotargs *args,
                                          void *dummy,
                                          struct cb_process_state *cps);
 
+extern void nfs4_check_drain_bc_complete(struct nfs4_session *ses);
+extern void nfs4_cb_take_slot(struct nfs_client *clp);
 #endif /* CONFIG_NFS_V4_1 */
 
 extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args,
@@ -145,7 +147,6 @@ extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args,
                                     struct cb_process_state *cps);
 extern __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy,
                                    struct cb_process_state *cps);
-
 #ifdef CONFIG_NFS_V4
 extern int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt);
 extern void nfs_callback_down(int minorversion);
diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index b70e46da16fc..c1bead2f3e04 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -253,6 +253,12 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
         if (clp == NULL)
                 goto out;
 
+        /* state manager is resetting the session */
+        if (test_bit(NFS4_SESSION_DRAINING, &clp->cl_session->session_state)) {
+                status = NFS4ERR_DELAY;
+                goto out;
+        }
+
         status = validate_seqid(&clp->cl_session->bc_slot_table, args);
         if (status)
                 goto out;
@@ -273,6 +279,7 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
         res->csr_slotid = args->csa_slotid;
         res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
         res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
+        nfs4_cb_take_slot(clp);
         cps->clp = clp; /* put in nfs4_callback_compound */
 
 out:
diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index dbd0d649805c..7a2d6c5864ca 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -596,6 +596,37 @@ preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
         return htonl(NFS_OK);
 }
 
+static void nfs4_callback_free_slot(struct nfs4_session *session)
+{
+        struct nfs4_slot_table *tbl = &session->bc_slot_table;
+
+        spin_lock(&tbl->slot_tbl_lock);
+        /*
+         * Let the state manager know callback processing done.
+         * A single slot, so highest used slotid is either 0 or -1
+         */
+        tbl->highest_used_slotid--;
+        nfs4_check_drain_bc_complete(session);
+        spin_unlock(&tbl->slot_tbl_lock);
+}
+
+static void nfs4_cb_free_slot(struct nfs_client *clp)
+{
+        if (clp && clp->cl_session)
+                nfs4_callback_free_slot(clp->cl_session);
+}
+
+/* A single slot, so highest used slotid is either 0 or -1 */
+void nfs4_cb_take_slot(struct nfs_client *clp)
+{
+        struct nfs4_slot_table *tbl = &clp->cl_session->bc_slot_table;
+
+        spin_lock(&tbl->slot_tbl_lock);
+        tbl->highest_used_slotid++;
+        BUG_ON(tbl->highest_used_slotid != 0);
+        spin_unlock(&tbl->slot_tbl_lock);
+}
+
 #else /* CONFIG_NFS_V4_1 */
 
 static __be32
@@ -604,6 +635,9 @@ preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
         return htonl(NFS4ERR_MINOR_VERS_MISMATCH);
 }
 
+static void nfs4_cb_free_slot(struct nfs_client *clp)
+{
+}
 #endif /* CONFIG_NFS_V4_1 */
 
 static __be32
@@ -724,6 +758,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
 
         *hdr_res.status = status;
         *hdr_res.nops = htonl(nops);
+        nfs4_cb_free_slot(cps.clp);
         nfs_put_client(cps.clp);
         dprintk("%s: done, status = %u\n", __func__, ntohl(status));
         return rpc_success;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e165c53db08f..18a4d5a9a4e9 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -356,9 +356,9 @@ nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *free_slot)
 }
 
 /*
- * Signal state manager thread if session is drained
+ * Signal state manager thread if session fore channel is drained
  */
-static void nfs41_check_drain_session_complete(struct nfs4_session *ses)
+static void nfs4_check_drain_fc_complete(struct nfs4_session *ses)
 {
         struct rpc_task *task;
 
@@ -372,8 +372,20 @@ static void nfs41_check_drain_session_complete(struct nfs4_session *ses)
         if (ses->fc_slot_table.highest_used_slotid != -1)
                 return;
 
-        dprintk("%s COMPLETE: Session Drained\n", __func__);
-        complete(&ses->complete);
+        dprintk("%s COMPLETE: Session Fore Channel Drained\n", __func__);
+        complete(&ses->fc_slot_table.complete);
+}
+
+/*
+ * Signal state manager thread if session back channel is drained
+ */
+void nfs4_check_drain_bc_complete(struct nfs4_session *ses)
+{
+        if (!test_bit(NFS4_SESSION_DRAINING, &ses->session_state) ||
+            ses->bc_slot_table.highest_used_slotid != -1)
+                return;
+        dprintk("%s COMPLETE: Session Back Channel Drained\n", __func__);
+        complete(&ses->bc_slot_table.complete);
 }
 
 static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
@@ -390,7 +402,7 @@ static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
 
         spin_lock(&tbl->slot_tbl_lock);
         nfs4_free_slot(tbl, res->sr_slot);
-        nfs41_check_drain_session_complete(res->sr_session);
+        nfs4_check_drain_fc_complete(res->sr_session);
         spin_unlock(&tbl->slot_tbl_lock);
         res->sr_slot = NULL;
 }
@@ -4777,17 +4789,17 @@ struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
         if (!session)
                 return NULL;
 
-        init_completion(&session->complete);
-
         tbl = &session->fc_slot_table;
         tbl->highest_used_slotid = -1;
         spin_lock_init(&tbl->slot_tbl_lock);
         rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, "ForeChannel Slot table");
+        init_completion(&tbl->complete);
 
         tbl = &session->bc_slot_table;
         tbl->highest_used_slotid = -1;
         spin_lock_init(&tbl->slot_tbl_lock);
         rpc_init_wait_queue(&tbl->slot_tbl_waitq, "BackChannel Slot table");
+        init_completion(&tbl->complete);
 
         session->session_state = 1<<NFS4_SESSION_INITING;
 
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 485e95e8fd62..6891dedd80f1 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -142,6 +142,11 @@ static int nfs41_setup_state_renewal(struct nfs_client *clp)
         return status;
 }
 
+/*
+ * Back channel returns NFS4ERR_DELAY for new requests when
+ * NFS4_SESSION_DRAINING is set so there is no work to be done when draining
+ * is ended.
+ */
 static void nfs4_end_drain_session(struct nfs_client *clp)
 {
         struct nfs4_session *ses = clp->cl_session;
@@ -165,22 +170,32 @@ static void nfs4_end_drain_session(struct nfs_client *clp)
         }
 }
 
-static int nfs4_begin_drain_session(struct nfs_client *clp)
+static int nfs4_wait_on_slot_tbl(struct nfs4_slot_table *tbl)
 {
-        struct nfs4_session *ses = clp->cl_session;
-        struct nfs4_slot_table *tbl = &ses->fc_slot_table;
-
         spin_lock(&tbl->slot_tbl_lock);
-        set_bit(NFS4_SESSION_DRAINING, &ses->session_state);
         if (tbl->highest_used_slotid != -1) {
-                INIT_COMPLETION(ses->complete);
+                INIT_COMPLETION(tbl->complete);
                 spin_unlock(&tbl->slot_tbl_lock);
-                return wait_for_completion_interruptible(&ses->complete);
+                return wait_for_completion_interruptible(&tbl->complete);
         }
         spin_unlock(&tbl->slot_tbl_lock);
         return 0;
 }
 
+static int nfs4_begin_drain_session(struct nfs_client *clp)
+{
+        struct nfs4_session *ses = clp->cl_session;
+        int ret = 0;
+
+        set_bit(NFS4_SESSION_DRAINING, &ses->session_state);
+        /* back channel */
+        ret = nfs4_wait_on_slot_tbl(&ses->bc_slot_table);
+        if (ret)
+                return ret;
+        /* fore channel */
+        return nfs4_wait_on_slot_tbl(&ses->fc_slot_table);
+}
+
 int nfs41_init_clientid(struct nfs_client *clp, struct rpc_cred *cred)
 {
         int status;
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 1eaa054a2c7d..e93ada0565fc 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -197,6 +197,7 @@ struct nfs4_slot_table {
                                                  * op for dynamic resizing */
         int             target_max_slots;       /* Set by CB_RECALL_SLOT as
                                                  * the new max_slots */
+        struct completion complete;
 };
 
 static inline int slot_idx(struct nfs4_slot_table *tbl, struct nfs4_slot *sp)
@@ -213,7 +214,6 @@ struct nfs4_session {
         unsigned long                   session_state;
         u32                             hash_alg;
         u32                             ssv_len;
-        struct completion               complete;
 
         /* The fore and back channel */
         struct nfs4_channel_attrs       fc_attrs;