NFS: Fix up TEST_STATEID and FREE_STATEID return code handling (377e507d) · Commits · 戴 / test

The TEST_STATEID and FREE_STATEID operations can return -NFS4ERR_BAD_STATEID, -NFS4ERR_OLD_STATEID, or -NFS4ERR_DEADSESSION. nfs41_{test,free}_stateid() should not pass these errors to nfs4_handle_exception() during state recovery, since that will recursively kick off state recovery again, resulting in a deadlock. In particular, when the TEST_STATEID operation returns NFS4_OK, res.status can contain one of these errors. _nfs41_test_stateid() replaces NFS4_OK with the value in res.status, which is then returned to callers. But res.status is not passed through nfs4_stat_to_errno(), and thus is a positive NFS4ERR value. Currently callers are only interested in !NFS4_OK, and nfs4_handle_exception() ignores positive values. Thus the res.status values are currently ignored by nfs4_handle_exception() and won't cause the deadlock above. Thanks to this missing negative, it is only when these operations fail (which is very rare) that a deadlock can occur. Bryan agrees the original intent was to return res.status as a negative NFS4ERR value to callers of nfs41_test_stateid(). Signed-off-by:

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

Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

+13 −11

Original line number	Diff line number	Diff line
		@@ -6578,10 +6578,9 @@ static int _nfs41_test_stateid(struct nfs_server server, nfs4_stateid stateid)

		nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
		status = nfs4_call_sync_sequence(server->client, server, &msg, &args.seq_args, &res.seq_res, 1);

		if (status == NFS_OK)
		return res.status;
		if (status != NFS_OK)
		return status;
		return -res.status;
		}

		static int nfs41_test_stateid(struct nfs_server server, nfs4_stateid stateid)
		@@ -6589,9 +6588,10 @@ static int nfs41_test_stateid(struct nfs_server server, nfs4_stateid stateid)
		struct nfs4_exception exception = { };
		int err;
		do {
		err = nfs4_handle_exception(server,
		_nfs41_test_stateid(server, stateid),
		&exception);
		err = _nfs41_test_stateid(server, stateid);
		if (err != -NFS4ERR_DELAY)
		break;
		nfs4_handle_exception(server, err, &exception);
		} while (exception.retry);
		return err;
		}
		@@ -6609,7 +6609,8 @@ static int _nfs4_free_stateid(struct nfs_server server, nfs4_stateid stateid)
		};

		nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
		return nfs4_call_sync_sequence(server->client, server, &msg, &args.seq_args, &res.seq_res, 1);
		return nfs4_call_sync_sequence(server->client, server, &msg,
		&args.seq_args, &res.seq_res, 1);
		}

		static int nfs41_free_stateid(struct nfs_server server, nfs4_stateid stateid)
		@@ -6617,9 +6618,10 @@ static int nfs41_free_stateid(struct nfs_server server, nfs4_stateid stateid)
		struct nfs4_exception exception = { };
		int err;
		do {
		err = nfs4_handle_exception(server,
		_nfs4_free_stateid(server, stateid),
		&exception);
		err = _nfs4_free_stateid(server, stateid);
		if (err != -NFS4ERR_DELAY)
		break;
		nfs4_handle_exception(server, err, &exception);
		} while (exception.retry);
		return err;
		}

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