telemetry: Instrument NFS error paths with structured error logging

Summary: Logs NFS SERVERFAULT errors to perfpipe_edenfs_errors across all NFS RPC handlers. Only unexpected failures (SERVERFAULT) are logged.

Reviewed By: vilatto

Differential Revision: D105984136

fbshipit-source-id: c46d403495a04d998847264c99a7f8cfb33b822d

Author: Chandhana Solainathan

eden/fs/nfs/BUCK

@@ -51,6 +51,8 @@ cpp_library(
         "//eden/common/utils:utils",
         "//eden/fs/privhelper:interface",
         "//eden/fs/store:context",
+        "//eden/fs/telemetry:error_info",
+        "//eden/fs/telemetry:error_logger",
         "//eden/fs/telemetry:fs_event_logger",
         "//eden/fs/telemetry:log_info",
         "//eden/fs/utils:clock",
@@ -70,6 +72,7 @@ cpp_library(
         "//eden/fs/nfs/rpc:server",
         "//eden/fs/telemetry:structured_logger",
         "//eden/fs/utils:process_access_log",
+        "//folly:exception_wrapper",
         "//folly:function",
     ],
 )

eden/fs/nfs/Nfsd3.cpp

@@ -12,6 +12,7 @@
 
 #include <optional>
 
+#include <folly/ExceptionWrapper.h>
 #include "eden/common/telemetry/TraceBus.h"
 #include "eden/common/utils/CaseSensitivity.h"
 #include "eden/fs/inodes/FsChannel.h"
@@ -33,6 +34,19 @@ class ProcessInfoCache;
 class EdenFsEventsLogger;
 class FsEventLogger;
 
+namespace detail {
+/**
+ * Log SERVERFAULT errors to structured error telemetry.
+ * Normal filesystem errors (ENOENT, EACCES, etc.) are not logged.
+ */
+void logNfsError(
+    nfsstat3 error,
+    const folly::exception_wrapper& ex,
+    ErrorLogger& errorLogger,
+    uint64_t inode,
+    const AbsolutePath& mountPath);
+} // namespace detail
+
 using TraceDetailedArgumentsHandle = std::shared_ptr<void>;
 
 enum class NfsInvalidationSource : uint8_t {

eden/fs/nfs/Nfsd3.h

@@ -8,9 +8,14 @@ cpp_unittest(
     supports_static_listing = False,
     deps = [
         "fbsource//third-party/googletest:gtest",
+        "//eden/common/utils:path",
+        "//eden/fs/config:config",
         "//eden/fs/nfs:dirlist",
         "//eden/fs/nfs:nfs_utils",
+        "//eden/fs/nfs:nfsd3",
         "//eden/fs/nfs:nfsd_rpc",
         "//eden/fs/nfs/testharness:xdr_test_utils",
+        "//eden/fs/telemetry:error_logger",
+        "//eden/fs/telemetry/test:capturing_scribe_logger",
     ],
 )

eden/fs/nfs/test/BUCK

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This software may be used and distributed according to the terms of the
+ * GNU General Public License version 2.
+ */
+
+#include <gtest/gtest.h>
+#include <stdexcept>
+#include <system_error>
+
+#include "eden/common/utils/PathFuncs.h"
+#include "eden/fs/config/EdenConfig.h"
+#include "eden/fs/config/ReloadableConfig.h"
+#include "eden/fs/nfs/Nfsd3.h"
+#include "eden/fs/telemetry/ErrorLogger.h"
+#include "eden/fs/telemetry/test/CapturingScribeLogger.h"
+
+using namespace facebook::eden;
+
+namespace {
+
+std::shared_ptr<ReloadableConfig> makeTestConfig() {
+  auto edenConfig = EdenConfig::createTestEdenConfig();
+  edenConfig->enableErrorLogging.setValue(
+      true, ConfigSourceType::Default, true);
+  return std::make_shared<ReloadableConfig>(edenConfig);
+}
+
+} // namespace
+
+TEST(NfsErrorLoggingTest, serverfaultIsLogged) {
+  auto scribe = std::make_shared<CapturingScribeLogger>();
+  auto config = makeTestConfig();
+  ErrorLogger logger(scribe, SessionInfo{}, config);
+
+  folly::exception_wrapper ex{std::runtime_error("backing store failure")};
+  detail::logNfsError(
+      nfsstat3::NFS3ERR_SERVERFAULT,
+      ex,
+      logger,
+      42,
+      canonicalPath("/mnt/repo"));
+
+  ASSERT_EQ(scribe->messages().size(), 1);
+  const auto& msg = scribe->messages()[0];
+  EXPECT_NE(msg.find("nfs"), std::string::npos)
+      << "Should contain nfs component, got: " << msg;
+  EXPECT_NE(msg.find("backing store failure"), std::string::npos)
+      << "Should contain error message, got: " << msg;
+  EXPECT_NE(msg.find("mnt"), std::string::npos)
+      << "Should contain mount point, got: " << msg;
+}
+
+TEST(NfsErrorLoggingTest, nonServerfaultIsNotLogged) {
+  auto scribe = std::make_shared<CapturingScribeLogger>();
+  auto config = makeTestConfig();
+  ErrorLogger logger(scribe, SessionInfo{}, config);
+
+  folly::exception_wrapper ex{
+      std::system_error(ENOENT, std::generic_category(), "file not found")};
+  detail::logNfsError(
+      nfsstat3::NFS3ERR_NOENT, ex, logger, 42, canonicalPath("/mnt/repo"));
+
+  EXPECT_EQ(scribe->messages().size(), 0)
+      << "Non-SERVERFAULT errors should not be logged";
+}

eden/fs/nfs/test/NfsErrorLoggingTest.cpp

@@ -1,8 +1,17 @@
 load("@fbcode_macros//build_defs:cpp_benchmark.bzl", "cpp_benchmark")
+load("@fbcode_macros//build_defs:cpp_library.bzl", "cpp_library")
 load("@fbcode_macros//build_defs:cpp_unittest.bzl", "cpp_unittest")
 
 oncall("scm_client_infra")
 
+cpp_library(
+    name = "capturing_scribe_logger",
+    headers = ["CapturingScribeLogger.h"],
+    exported_deps = [
+        "//eden/common/telemetry:scribe_logger",
+    ],
+)
+
 cpp_unittest(
     name = "task_trace_test",
     srcs = [

eden/fs/telemetry/test/BUCK

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This software may be used and distributed according to the terms of the
+ * GNU General Public License version 2.
+ */
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "eden/common/telemetry/ScribeLogger.h"
+
+namespace facebook::eden {
+
+/**
+ * A ScribeLogger that captures messages for test verification.
+ */
+class CapturingScribeLogger : public ScribeLogger {
+ public:
+  void log(std::string message) override {
+    messages_.push_back(std::move(message));
+  }
+
+  const std::vector<std::string>& messages() const {
+    return messages_;
+  }
+
+ private:
+  std::vector<std::string> messages_;
+};
+
+} // namespace facebook::eden