NFS: Introduce nfs_detach_delegations()

Clean up:  Refactor code that takes clp->cl_lock and calls
nfs_detach_delegations_locked() into its own function.

While we're changing the call sites, get rid of the second parameter
and the logic in nfs_detach_delegations_locked() that uses it, since
callers always set that parameter of nfs_detach_delegations_locked()
to NULL.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/delegation.c

@@ -175,9 +175,9 @@ static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation
 	return inode;
 }
 
-static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfsi,
-							   const nfs4_stateid *stateid,
-							   struct nfs_client *clp)
+static struct nfs_delegation *
+nfs_detach_delegation_locked(struct nfs_inode *nfsi,
+			     struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation =
 		rcu_dereference_protected(nfsi->delegation,
@@ -185,22 +185,29 @@ static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfs
 
 	if (delegation == NULL)
 		goto nomatch;
+
 	spin_lock(&delegation->lock);
-	if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
-				sizeof(delegation->stateid.data)) != 0)
-		goto nomatch_unlock;
 	list_del_rcu(&delegation->super_list);
 	delegation->inode = NULL;
 	nfsi->delegation_state = 0;
 	rcu_assign_pointer(nfsi->delegation, NULL);
 	spin_unlock(&delegation->lock);
 	return delegation;
-nomatch_unlock:
-	spin_unlock(&delegation->lock);
 nomatch:
 	return NULL;
 }
 
+static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
+						    struct nfs_client *clp)
+{
+	struct nfs_delegation *delegation;
+
+	spin_lock(&clp->cl_lock);
+	delegation = nfs_detach_delegation_locked(nfsi, clp);
+	spin_unlock(&clp->cl_lock);
+	return delegation;
+}
+
 /*
  * Set up a delegation on an inode
  */
@@ -246,7 +253,7 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
 			delegation = NULL;
 			goto out;
 		}
-		freeme = nfs_detach_delegation_locked(nfsi, NULL, clp);
+		freeme = nfs_detach_delegation_locked(nfsi, clp);
 	}
 	list_add_rcu(&delegation->super_list, &clp->cl_delegations);
 	nfsi->delegation_state = delegation->type;
@@ -307,9 +314,7 @@ restart:
 		inode = nfs_delegation_grab_inode(delegation);
 		if (inode == NULL)
 			continue;
-		spin_lock(&clp->cl_lock);
-		delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL, clp);
-		spin_unlock(&clp->cl_lock);
+		delegation = nfs_detach_delegation(NFS_I(inode), clp);
 		rcu_read_unlock();
 		if (delegation != NULL) {
 			filemap_flush(inode->i_mapping);
@@ -338,9 +343,7 @@ void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 	struct nfs_delegation *delegation;
 
 	if (rcu_access_pointer(nfsi->delegation) != NULL) {
-		spin_lock(&clp->cl_lock);
-		delegation = nfs_detach_delegation_locked(nfsi, NULL, clp);
-		spin_unlock(&clp->cl_lock);
+		delegation = nfs_detach_delegation(nfsi, clp);
 		if (delegation != NULL)
 			nfs_do_return_delegation(inode, delegation, 0);
 	}
@@ -354,9 +357,7 @@ int nfs_inode_return_delegation(struct inode *inode)
 	int err = 0;
 
 	if (rcu_access_pointer(nfsi->delegation) != NULL) {
-		spin_lock(&clp->cl_lock);
-		delegation = nfs_detach_delegation_locked(nfsi, NULL, clp);
-		spin_unlock(&clp->cl_lock);
+		delegation = nfs_detach_delegation(nfsi, clp);
 		if (delegation != NULL) {
 			nfs_wb_all(inode);
 			err = __nfs_inode_return_delegation(inode, delegation, 1);
@@ -530,9 +531,7 @@ restart:
 		inode = nfs_delegation_grab_inode(delegation);
 		if (inode == NULL)
 			continue;
-		spin_lock(&clp->cl_lock);
-		delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL, clp);
-		spin_unlock(&clp->cl_lock);
+		delegation = nfs_detach_delegation(NFS_I(inode), clp);
 		rcu_read_unlock();
 		if (delegation != NULL)
 			nfs_free_delegation(delegation);