NFSv4: Fix an atomicity problem in CLOSE

If we are to remove the serialisation of OPEN/CLOSE, then we need to
ensure that the stateid sent as part of a CLOSE operation does not
change after we test the state in nfs4_close_prepare.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4proc.c

@@ -2587,6 +2587,11 @@ static void nfs4_close_done(struct rpc_task *task, void *data)
 		case -NFS4ERR_OLD_STATEID:
 		case -NFS4ERR_BAD_STATEID:
 		case -NFS4ERR_EXPIRED:
+			if (!nfs4_stateid_match(&calldata->arg.stateid,
+						&state->stateid)) {
+				rpc_restart_call_prepare(task);
+				goto out_release;
+			}
 			if (calldata->arg.fmode == 0)
 				break;
 		default:
@@ -2619,6 +2624,7 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
 	is_rdwr = test_bit(NFS_O_RDWR_STATE, &state->flags);
 	is_rdonly = test_bit(NFS_O_RDONLY_STATE, &state->flags);
 	is_wronly = test_bit(NFS_O_WRONLY_STATE, &state->flags);
+	nfs4_stateid_copy(&calldata->arg.stateid, &state->stateid);
 	/* Calculate the change in open mode */
 	calldata->arg.fmode = 0;
 	if (state->n_rdwr == 0) {
@@ -2757,7 +2763,6 @@ int nfs4_do_close(struct nfs4_state *state, gfp_t gfp_mask, int wait)
 	calldata->inode = state->inode;
 	calldata->state = state;
 	calldata->arg.fh = NFS_FH(state->inode);
-	calldata->arg.stateid = &state->open_stateid;
 	/* Serialization for the sequence id */
 	calldata->arg.seqid = nfs_alloc_seqid(&state->owner->so_seqid, gfp_mask);
 	if (calldata->arg.seqid == NULL)

fs/nfs/nfs4xdr.c

@@ -1125,7 +1125,7 @@ static void encode_close(struct xdr_stream *xdr, const struct nfs_closeargs *arg
 {
 	encode_op_hdr(xdr, OP_CLOSE, decode_close_maxsz, hdr);
 	encode_nfs4_seqid(xdr, arg->seqid);
-	encode_nfs4_stateid(xdr, arg->stateid);
+	encode_nfs4_stateid(xdr, &arg->stateid);
 }
 
 static void encode_commit(struct xdr_stream *xdr, const struct nfs_commitargs *args, struct compound_hdr *hdr)
@@ -1530,7 +1530,7 @@ static void encode_open_confirm(struct xdr_stream *xdr, const struct nfs_open_co
 static void encode_open_downgrade(struct xdr_stream *xdr, const struct nfs_closeargs *arg, struct compound_hdr *hdr)
 {
 	encode_op_hdr(xdr, OP_OPEN_DOWNGRADE, decode_open_downgrade_maxsz, hdr);
-	encode_nfs4_stateid(xdr, arg->stateid);
+	encode_nfs4_stateid(xdr, &arg->stateid);
 	encode_nfs4_seqid(xdr, arg->seqid);
 	encode_share_access(xdr, arg->fmode);
 }

include/linux/nfs_xdr.h

@@ -389,7 +389,7 @@ struct nfs_open_confirmres {
 struct nfs_closeargs {
 	struct nfs4_sequence_args	seq_args;
 	struct nfs_fh *         fh;
-	nfs4_stateid *		stateid;
+	nfs4_stateid 		stateid;
 	struct nfs_seqid *	seqid;
 	fmode_t			fmode;
 	const u32 *		bitmask;