NFSv4.1: Handle NFS4ERR_BADSLOT errors correctly

Most (all) NFS4ERR_BADSLOT errors are due to the client failing to
respect the server's sr_highest_slotid limit. This mainly happens
due to reordered RPC requests.
The way to handle it is simply to drop the slot that we're using,
and retry using the new highest_slotid limits.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 92bd799..a4692e9 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -422,6 +422,7 @@ static int nfs41_sequence_done(struct rpc_task *task, struct nfs4_sequence_res *
        struct nfs4_slot *slot;
        unsigned long timestamp;
        struct nfs_client *clp;
+       int ret = 1;
 
        /*
         * sr_status remains 1 if an RPC level error occurred. The server
@@ -462,6 +463,16 @@ static int nfs41_sequence_done(struct rpc_task *task, struct nfs4_sequence_res *
                        slot->slot_nr,
                        slot->seq_nr);
                goto out_retry;
+       case -NFS4ERR_BADSLOT:
+               /*
+                * The slot id we used was probably retired. Try again
+                * using a different slot id.
+                */
+               if (rpc_restart_call_prepare(task)) {
+                       task->tk_status = 0;
+                       ret = 0;
+               }
+               break;
        default:
                /* Just update the slot sequence no. */
                ++slot->seq_nr;
@@ -470,7 +481,7 @@ out:
        /* The session may be reset by one of the error handlers. */
        dprintk("%s: Error %d free the slot \n", __func__, res->sr_status);
        nfs41_sequence_free_slot(res);
-       return 1;
+       return ret;
 out_retry:
        if (!rpc_restart_call(task))
                goto out;