some polishing

src/libraries/Native/Unix/System.Native/pal_io.h

@@ -711,7 +711,7 @@ PALEXPORT char* SystemNative_RealPath(const char* path);
 PALEXPORT int32_t SystemNative_GetPeerID(intptr_t socket, uid_t* euid);
 
 /**
-* Returns file system type on success, or -1 on error or 0 when fstatfs is not supported.
+* Returns file system type on success, or -1 on error.
 */
 PALEXPORT int64_t SystemNative_GetFileSystemType(intptr_t fd);
 

src/libraries/System.Private.CoreLib/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs

@@ -10,7 +10,8 @@ namespace Microsoft.Win32.SafeHandles
 {
     public sealed partial class SafeFileHandle : SafeHandleZeroOrMinusOneIsInvalid
     {
-        internal static bool DisableFileLocking { get; } = AppContextConfigHelper.GetBooleanConfig("System.IO.DisableFileLocking", "DOTNET_SYSTEM_IO_DISABLEFILELOCKING", defaultValue: false);
+        internal static bool DisableFileLocking { get; } = OperatingSystem.IsBrowser() // #40065: Emscripten does not support file locking
+            || AppContextConfigHelper.GetBooleanConfig("System.IO.DisableFileLocking", "DOTNET_SYSTEM_IO_DISABLEFILELOCKING", defaultValue: false);
 
         // not using bool? as it's not thread safe
         private volatile NullableBool _canSeek = NullableBool.Undefined;
@@ -328,11 +329,7 @@ private bool CanLockTheFile(Interop.Sys.LockOperations lockOperation, FileAccess
         {
             Debug.Assert(lockOperation == Interop.Sys.LockOperations.LOCK_EX || lockOperation == Interop.Sys.LockOperations.LOCK_SH);
 
-            if (OperatingSystem.IsBrowser())
-            {
-                return false; // #40065: Emscripten does not support file locking
-            }
-            else if (DisableFileLocking)
+            if (DisableFileLocking)
             {
                 return false;
             }