NFS handle COPY reply CB_OFFLOAD call race

It's possible that server replies back with CB_OFFLOAD call and
COPY reply at the same time such that client will process
CB_OFFLOAD before reply to COPY. For that keep a list of pending
callback stateids received and then before waiting on completion
check the pending list.

Cleanup any pending copies on the client shutdown.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index acdda259912e..cd733649646b 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -681,11 +681,12 @@ __be32 nfs4_callback_offload(void *data, void *dummy,
 	struct cb_offloadargs *args = data;
 	struct nfs_server *server;
 	struct nfs4_copy_state *copy;
+	bool found = false;
 
+	spin_lock(&cps->clp->cl_lock);
 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &cps->clp->cl_superblocks,
 				client_link) {
-		spin_lock(&server->nfs_client->cl_lock);
 		list_for_each_entry(copy, &server->ss_copies, copies) {
 			if (memcmp(args->coa_stateid.other,
 					copy->stateid.other,
@@ -693,13 +694,23 @@ __be32 nfs4_callback_offload(void *data, void *dummy,
 				continue;
 			nfs4_copy_cb_args(copy, args);
 			complete(&copy->completion);
-			spin_unlock(&server->nfs_client->cl_lock);
+			found = true;
 			goto out;
 		}
-		spin_unlock(&server->nfs_client->cl_lock);
 	}
 out:
 	rcu_read_unlock();
+	if (!found) {
+		copy = kzalloc(sizeof(struct nfs4_copy_state), GFP_NOFS);
+		if (!copy) {
+			spin_unlock(&cps->clp->cl_lock);
+			return htonl(NFS4ERR_SERVERFAULT);
+		}
+		memcpy(&copy->stateid, &args->coa_stateid, NFS4_STATEID_SIZE);
+		nfs4_copy_cb_args(copy, args);
+		list_add_tail(&copy->copies, &cps->clp->pending_cb_stateids);
+	}
+	spin_unlock(&cps->clp->cl_lock);
 
 	return 0;
 }