nfs41: return layout on last close

If client has valid delegation, do not return layout on close at all.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4proc.c

@@ -2655,6 +2655,48 @@ static const struct rpc_call_ops nfs4_close_ops = {
 	.rpc_release = nfs4_free_closedata,
 };
 
+static bool nfs4_state_has_opener(struct nfs4_state *state)
+{
+	/* first check existing openers */
+	if (test_bit(NFS_O_RDONLY_STATE, &state->flags) != 0 &&
+	    state->n_rdonly != 0)
+		return true;
+
+	if (test_bit(NFS_O_WRONLY_STATE, &state->flags) != 0 &&
+	    state->n_wronly != 0)
+		return true;
+
+	if (test_bit(NFS_O_RDWR_STATE, &state->flags) != 0 &&
+	    state->n_rdwr != 0)
+		return true;
+
+	return false;
+}
+
+static bool nfs4_roc(struct inode *inode)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_open_context *ctx;
+	struct nfs4_state *state;
+
+	spin_lock(&inode->i_lock);
+	list_for_each_entry(ctx, &nfsi->open_files, list) {
+		state = ctx->state;
+		if (state == NULL)
+			continue;
+		if (nfs4_state_has_opener(state)) {
+			spin_unlock(&inode->i_lock);
+			return false;
+		}
+	}
+	spin_unlock(&inode->i_lock);
+
+	if (nfs4_check_delegation(inode, FMODE_READ))
+		return false;
+
+	return pnfs_roc(inode);
+}
+
 /* 
  * It is possible for data to be read/written from a mem-mapped file 
  * after the sys_close call (which hits the vfs layer as a flush).
@@ -2705,7 +2747,7 @@ int nfs4_do_close(struct nfs4_state *state, gfp_t gfp_mask, int wait)
 	calldata->res.fattr = &calldata->fattr;
 	calldata->res.seqid = calldata->arg.seqid;
 	calldata->res.server = server;
-	calldata->roc = pnfs_roc(state->inode);
+	calldata->roc = nfs4_roc(state->inode);
 	nfs_sb_active(calldata->inode->i_sb);
 
 	msg.rpc_argp = &calldata->arg;