NFSv4.1: Reset the sequence number for slots that have been deallocated

When the server tells us that it is dynamically resizing the session
replay cache, we should reset the sequence number for those slots
that have been deallocated.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -498,6 +498,22 @@ static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
 	tbl->generation++;
 }
 
+static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
+		u32 highest_slotid)
+{
+	unsigned int max_slotid, i;
+
+	if (tbl->server_highest_slotid == highest_slotid)
+		return;
+	if (tbl->highest_used_slotid > highest_slotid)
+		return;
+	max_slotid = min(tbl->max_slots - 1, highest_slotid);
+	/* Reset the seq_nr for deallocated slots */
+	for (i = tbl->server_highest_slotid + 1; i <= max_slotid; i++)
+		tbl->slots[i].seq_nr = 1;
+	tbl->server_highest_slotid = highest_slotid;
+}
+
 static void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
 		struct nfs4_slot *slot,
 		struct nfs4_sequence_res *res)
@@ -505,6 +521,7 @@ static void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
 	spin_lock(&tbl->slot_tbl_lock);
 	if (tbl->generation != slot->generation)
 		goto out;
+	nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
 	nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
 out:
 	spin_unlock(&tbl->slot_tbl_lock);
@@ -5718,6 +5735,7 @@ static void nfs4_add_and_init_slots(struct nfs4_slot_table *tbl,
 	}
 	tbl->highest_used_slotid = NFS4_NO_SLOT;
 	tbl->target_highest_slotid = max_slots - 1;
+	tbl->server_highest_slotid = max_slots - 1;
 	for (i = 0; i < tbl->max_slots; i++)
 		tbl->slots[i].seq_nr = ivalue;
 	spin_unlock(&tbl->slot_tbl_lock);

fs/nfs/nfs4xdr.c

@@ -5550,8 +5550,8 @@ static int decode_sequence(struct xdr_stream *xdr,
 		dprintk("%s Invalid slot id\n", __func__);
 		goto out_err;
 	}
-	/* highest slot id - currently not processed */
-	dummy = be32_to_cpup(p++);
+	/* highest slot id */
+	res->sr_highest_slotid = be32_to_cpup(p++);
 	/* target highest slot id */
 	res->sr_target_highest_slotid = be32_to_cpup(p++);
 	/* result flags */

include/linux/nfs_fs_sb.h

@@ -218,6 +218,7 @@ struct nfs4_slot_table {
 	u32		highest_used_slotid;	/* sent to server on each SEQ.
 						 * op for dynamic resizing */
 	u32		target_highest_slotid;	/* Server max_slot target */
+	u32		server_highest_slotid;	/* Server highest slotid */
 	unsigned long	generation;		/* Generation counter for
 						   target_highest_slotid */
 	struct completion complete;

include/linux/nfs_xdr.h

@@ -203,6 +203,7 @@ struct nfs4_sequence_res {
 	struct nfs4_slot	*sr_slot;	/* slot used to send request */
 	int			sr_status;	/* sequence operation status */
 	u32			sr_status_flags;
+	u32			sr_highest_slotid;
 	u32			sr_target_highest_slotid;
 };