Add user tag spreading functionality to VM and use in file

User tags in a dynamic trace enabled VM are spread throughout the system
in the same way as seq_trace tokens. This is used by the file module
and various other modules to get hold of the tag from the user process
without changing the protocol.

3 files changed, 117 insertions, 164 deletions

diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index aecb9f7923..3a618976f5 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -39,7 +39,7 @@
 -export([ipread_s32bu_p32bu/3]).
 %% Generic file contents.
 -export([open/2, close/1, advise/4,
-	 read/2, write/2,
+	 read/2, write/2, 
 	 pread/2, pread/3, pwrite/2, pwrite/3,
 	 read_line/1,
 	 position/2, truncate/1, datasync/1, sync/1,
@@ -62,7 +62,7 @@
 
 %% Internal export to prim_file and ram_file until they implement
 %% an efficient copy themselves.
--export([copy_opened/4]).
+-export([copy_opened/3]).
 
 -export([ipread_s32bu_p32bu_int/3]).
 
@@ -166,7 +166,7 @@ pid2name(Pid) when is_pid(Pid) ->
       Reason :: posix().
 
 get_cwd() ->
-    call(get_cwd, [no_drive, get_dtrace_utag()]).
+    call(get_cwd, []).
 
 -spec get_cwd(Drive) -> {ok, Dir} | {error, Reason} when
       Drive :: string(),
@@ -174,21 +174,21 @@ get_cwd() ->
       Reason :: posix() | badarg.
 
 get_cwd(Drive) ->
-    check_and_call(get_cwd, [file_name(Drive), get_dtrace_utag()]).
+    check_and_call(get_cwd, [file_name(Drive)]).
 
 -spec set_cwd(Dir) -> ok | {error, Reason} when
       Dir :: name(),
       Reason :: posix() | badarg.
 
 set_cwd(Dirname) -> 
-    check_and_call(set_cwd, [file_name(Dirname), get_dtrace_utag()]).
+    check_and_call(set_cwd, [file_name(Dirname)]).
 
 -spec delete(Filename) -> ok | {error, Reason} when
       Filename :: name(),
       Reason :: posix() | badarg.
 
 delete(Name) ->
-    check_and_call(delete, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(delete, [file_name(Name)]).
 
 -spec rename(Source, Destination) -> ok | {error, Reason} when
       Source :: name(),
@@ -196,21 +196,21 @@ delete(Name) ->
       Reason :: posix() | badarg.
 
 rename(From, To) ->
-    check_and_call(rename, [file_name(From), file_name(To), get_dtrace_utag()]).
+    check_and_call(rename, [file_name(From), file_name(To)]).
 
 -spec make_dir(Dir) -> ok | {error, Reason} when
       Dir :: name(),
       Reason :: posix() | badarg.
 
 make_dir(Name) ->
-    check_and_call(make_dir, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(make_dir, [file_name(Name)]).
 
 -spec del_dir(Dir) -> ok | {error, Reason} when
       Dir :: name(),
       Reason :: posix() | badarg.
 
 del_dir(Name) ->
-    check_and_call(del_dir, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(del_dir, [file_name(Name)]).
 
 -spec read_file_info(Filename) -> {ok, FileInfo} | {error, Reason} when
       Filename :: name(),
@@ -218,7 +218,7 @@ del_dir(Name) ->
       Reason :: posix() | badarg.
 
 read_file_info(Name) ->
-    check_and_call(read_file_info, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(read_file_info, [file_name(Name)]).
 
 -spec read_file_info(Filename, Opts) -> {ok, FileInfo} | {error, Reason} when
       Filename :: name(),
@@ -227,12 +227,12 @@ read_file_info(Name) ->
       Reason :: posix() | badarg.
 
 read_file_info(Name, Opts) when is_list(Opts) ->
-    check_and_call(read_file_info, [file_name(Name), Opts, get_dtrace_utag()]).
+    check_and_call(read_file_info, [file_name(Name), Opts]).
 
 -spec altname(Name :: name()) -> any().
 
 altname(Name) ->
-    check_and_call(altname, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(altname, [file_name(Name)]).
 
 -spec read_link_info(Name) -> {ok, FileInfo} | {error, Reason} when
       Name :: name(),
@@ -240,7 +240,7 @@ altname(Name) ->
       Reason :: posix() | badarg.
 
 read_link_info(Name) ->
-    check_and_call(read_link_info, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(read_link_info, [file_name(Name)]).
 
 -spec read_link_info(Name, Opts) -> {ok, FileInfo} | {error, Reason} when
       Name :: name(),
@@ -249,7 +249,7 @@ read_link_info(Name) ->
       Reason :: posix() | badarg.
 
 read_link_info(Name, Opts) when is_list(Opts) ->
-    check_and_call(read_link_info, [file_name(Name),Opts, get_dtrace_utag()]).
+    check_and_call(read_link_info, [file_name(Name),Opts]).
 
 
 -spec read_link(Name) -> {ok, Filename} | {error, Reason} when
@@ -258,7 +258,7 @@ read_link_info(Name, Opts) when is_list(Opts) ->
       Reason :: posix() | badarg.
 
 read_link(Name) ->
-    check_and_call(read_link, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(read_link, [file_name(Name)]).
 
 -spec write_file_info(Filename, FileInfo) -> ok | {error, Reason} when
       Filename :: name(),
@@ -266,7 +266,7 @@ read_link(Name) ->
       Reason :: posix() | badarg.
 
 write_file_info(Name, Info = #file_info{}) ->
-    check_and_call(write_file_info, [file_name(Name), Info, get_dtrace_utag()]).
+    check_and_call(write_file_info, [file_name(Name), Info]).
 
 -spec write_file_info(Filename, FileInfo, Opts) -> ok | {error, Reason} when
       Filename :: name(),
@@ -275,7 +275,7 @@ write_file_info(Name, Info = #file_info{}) ->
       Reason :: posix() | badarg.
 
 write_file_info(Name, Info = #file_info{}, Opts) when is_list(Opts) ->
-    check_and_call(write_file_info, [file_name(Name), Info, Opts, get_dtrace_utag()]).
+    check_and_call(write_file_info, [file_name(Name), Info, Opts]).
 
 -spec list_dir(Dir) -> {ok, Filenames} | {error, Reason} when
       Dir :: name(),
@@ -283,7 +283,7 @@ write_file_info(Name, Info = #file_info{}, Opts) when is_list(Opts) ->
       Reason :: posix() | badarg.
 
 list_dir(Name) ->
-    check_and_call(list_dir, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(list_dir, [file_name(Name)]).
 
 -spec read_file(Filename) -> {ok, Binary} | {error, Reason} when
       Filename :: name(),
@@ -291,7 +291,7 @@ list_dir(Name) ->
       Reason :: posix() | badarg | terminated | system_limit.
 
 read_file(Name) ->
-    check_and_call(read_file, [file_name(Name), get_dtrace_utag()]).
+    check_and_call(read_file, [file_name(Name)]).
 
 -spec make_link(Existing, New) -> ok | {error, Reason} when
       Existing :: name(),
@@ -299,7 +299,7 @@ read_file(Name) ->
       Reason :: posix() | badarg.
 
 make_link(Old, New) ->
-    check_and_call(make_link, [file_name(Old), file_name(New), get_dtrace_utag()]).
+    check_and_call(make_link, [file_name(Old), file_name(New)]).
 
 -spec make_symlink(Existing, New) -> ok | {error, Reason} when
       Existing :: name(),
@@ -307,7 +307,7 @@ make_link(Old, New) ->
       Reason :: posix() | badarg.
 
 make_symlink(Old, New) ->
-    check_and_call(make_symlink, [file_name(Old), file_name(New), get_dtrace_utag()]).
+    check_and_call(make_symlink, [file_name(Old), file_name(New)]).
 
 -spec write_file(Filename, Bytes) -> ok | {error, Reason} when
       Filename :: name(),
@@ -315,7 +315,7 @@ make_symlink(Old, New) ->
       Reason :: posix() | badarg | terminated | system_limit.
 
 write_file(Name, Bin) ->
-    check_and_call(write_file, [file_name(Name), make_binary(Bin), get_dtrace_utag()]).
+    check_and_call(write_file, [file_name(Name), make_binary(Bin)]).
 
 %% This whole operation should be moved to the file_server and prim_file
 %% when it is time to change file server protocol again.
@@ -367,7 +367,7 @@ raw_write_file_info(Name, #file_info{} = Info) ->
     case check_args(Args) of
 	ok ->
 	    [FileName] = Args,
-	    ?PRIM_FILE:write_file_info(FileName, Info, get_dtrace_utag());
+	    ?PRIM_FILE:write_file_info(FileName, Info);
 	Error ->
 	    Error
     end.
@@ -400,7 +400,7 @@ open(Item, ModeList) when is_list(ModeList) ->
 			    [FileName | _] = Args,
 			    %% We rely on the returned Handle (in {ok, Handle})
 			    %% being a pid() or a #file_descriptor{}
-			    ?PRIM_FILE:open(FileName, ModeList, get_dtrace_utag());
+			    ?PRIM_FILE:open(FileName, ModeList);
 			Error ->
 			    Error
 		    end
@@ -421,7 +421,7 @@ open(Item, ModeList) when is_list(ModeList) ->
 		    case check_args(Args) of 
 			ok ->
 			    [FileName | _] = Args,
-			    call(open, [FileName, ModeList, get_dtrace_utag()]);
+			    call(open, [FileName, ModeList]);
 			Error ->
 			    Error
 		    end
@@ -466,10 +466,7 @@ close(_) ->
 advise(File, Offset, Length, Advise) when is_pid(File) ->
     R = file_request(File, {advise, Offset, Length, Advise}),
     wait_file_reply(File, R);
-advise(#file_descriptor{module = prim_file = Module} = Handle, Offset, Length, Advise) ->
-    Module:advise(Handle, Offset, Length, Advise, get_dtrace_utag());
 advise(#file_descriptor{module = Module} = Handle, Offset, Length, Advise) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:advise(Handle, Offset, Length, Advise);
 advise(_, _, _, _) ->
     {error, badarg}.
@@ -480,25 +477,17 @@ advise(_, _, _, _) ->
       Data :: string() | binary(),
       Reason :: posix() | badarg | terminated.
 
-read(File, Sz) ->
-    read(File, Sz, get_dtrace_utag()).
-
-read(File, Sz, _DTraceUtag)
-  when (is_pid(File) orelse is_atom(File)), is_integer(Sz), Sz >= 0 ->
+read(File, Sz) when (is_pid(File) orelse is_atom(File)), is_integer(Sz), Sz >= 0 ->
     case io:request(File, {get_chars, '', Sz}) of
 	Data when is_list(Data); is_binary(Data) ->
 	    {ok, Data};
 	Other ->
 	    Other
     end;
-read(#file_descriptor{module = prim_file = Module} = Handle, Sz, DTraceUtag)
-  when is_integer(Sz), Sz >= 0 ->
-    Module:read(Handle, Sz, DTraceUtag);
-read(#file_descriptor{module = Module} = Handle, Sz, _DTraceUtag)
+read(#file_descriptor{module = Module} = Handle, Sz) 
   when is_integer(Sz), Sz >= 0 ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:read(Handle, Sz);
-read(_, _, _) ->
+read(_, _) ->
     {error, badarg}.
 
 -spec read_line(IoDevice) -> {ok, Data} | eof | {error, Reason} when
@@ -513,10 +502,7 @@ read_line(File) when (is_pid(File) orelse is_atom(File)) ->
 	Other ->
 	    Other
     end;
-read_line(#file_descriptor{module = prim_file = Module} = Handle) ->
-    Module:read_line(Handle, get_dtrace_utag());
 read_line(#file_descriptor{module = Module} = Handle) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:read_line(Handle);
 read_line(_) ->
     {error, badarg}.
@@ -530,10 +516,7 @@ read_line(_) ->
 
 pread(File, L) when is_pid(File), is_list(L) ->
     pread_int(File, L, []);
-pread(#file_descriptor{module = prim_file = Module} = Handle, L) when is_list(L) ->
-    Module:pread(Handle, L, get_dtrace_utag());
 pread(#file_descriptor{module = Module} = Handle, L) when is_list(L) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:pread(Handle, L);
 pread(_, _) ->
     {error, badarg}.
@@ -565,7 +548,6 @@ pread(File, At, Sz) when is_pid(File), is_integer(Sz), Sz >= 0 ->
     wait_file_reply(File, R);
 pread(#file_descriptor{module = Module} = Handle, Offs, Sz) 
   when is_integer(Sz), Sz >= 0 ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:pread(Handle, Offs, Sz);
 pread(_, _, _) ->
     {error, badarg}.
@@ -575,22 +557,16 @@ pread(_, _, _) ->
       Bytes :: iodata(),
       Reason :: posix() | badarg | terminated.
 
-write(File, Bytes) ->
-    write(File, Bytes, get_dtrace_utag()).
-
-write(File, Bytes, _DTraceUtag) when (is_pid(File) orelse is_atom(File)) ->
+write(File, Bytes) when (is_pid(File) orelse is_atom(File)) ->
     case make_binary(Bytes) of
 	Bin when is_binary(Bin) ->
 	    io:request(File, {put_chars,Bin});
 	Error ->
 	    Error
     end;
-write(#file_descriptor{module = prim_file = Module} = Handle, Bytes, DTraceUtag) ->
-    Module:write(Handle, Bytes, DTraceUtag);
-write(#file_descriptor{module = Module} = Handle, Bytes, _DTraceUtag) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
+write(#file_descriptor{module = Module} = Handle, Bytes) ->
     Module:write(Handle, Bytes);
-write(_, _, _) ->
+write(_, _) ->
     {error, badarg}.
 
 -spec pwrite(IoDevice, LocBytes) -> ok | {error, {N, Reason}} when
@@ -601,10 +577,7 @@ write(_, _, _) ->
 
 pwrite(File, L) when is_pid(File), is_list(L) ->
     pwrite_int(File, L, 0);
-pwrite(#file_descriptor{module = prim_file = Module} = Handle, L) when is_list(L) ->
-    Module:pwrite(Handle, L, get_dtrace_utag());
 pwrite(#file_descriptor{module = Module} = Handle, L) when is_list(L) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:pwrite(Handle, L);
 pwrite(_, _) ->
     {error, badarg}.
@@ -631,7 +604,6 @@ pwrite(File, At, Bytes) when is_pid(File) ->
     R = file_request(File, {pwrite, At, Bytes}),
     wait_file_reply(File, R);
 pwrite(#file_descriptor{module = Module} = Handle, Offs, Bytes) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:pwrite(Handle, Offs, Bytes);
 pwrite(_, _, _) ->
     {error, badarg}.
@@ -643,10 +615,7 @@ pwrite(_, _, _) ->
 datasync(File) when is_pid(File) ->
     R = file_request(File, datasync),
     wait_file_reply(File, R);
-datasync(#file_descriptor{module = prim_file = Module} = Handle) ->
-    Module:datasync(Handle, get_dtrace_utag());
 datasync(#file_descriptor{module = Module} = Handle) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:datasync(Handle);
 datasync(_) ->
     {error, badarg}.
@@ -658,10 +627,7 @@ datasync(_) ->
 sync(File) when is_pid(File) ->
     R = file_request(File, sync),
     wait_file_reply(File, R);
-sync(#file_descriptor{module = prim_file = Module} = Handle) ->
-    Module:sync(Handle, get_dtrace_utag());
 sync(#file_descriptor{module = Module} = Handle) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:sync(Handle);
 sync(_) ->
     {error, badarg}.
@@ -675,10 +641,7 @@ sync(_) ->
 position(File, At) when is_pid(File) ->
     R = file_request(File, {position,At}),
     wait_file_reply(File, R);
-position(#file_descriptor{module = prim_file = Module} = Handle, At) ->
-    Module:position(Handle, At, get_dtrace_utag());
 position(#file_descriptor{module = Module} = Handle, At) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:position(Handle, At);
 position(_, _) ->
     {error, badarg}.
@@ -690,10 +653,7 @@ position(_, _) ->
 truncate(File) when is_pid(File) ->
     R = file_request(File, truncate),
     wait_file_reply(File, R);
-truncate(#file_descriptor{module = prim_file = Module} = Handle) ->
-    Module:truncate(Handle, get_dtrace_utag());
 truncate(#file_descriptor{module = Module} = Handle) ->
-    %% DTrace TODO: ram_file and other file drivers not yet DTrace'ified.
     Module:truncate(Handle);
 truncate(_) ->
     {error, badarg}.
@@ -734,7 +694,7 @@ copy_int(Source, Dest, Length)
   when is_pid(Source), is_pid(Dest);
        is_pid(Source), is_record(Dest, file_descriptor);
        is_record(Source, file_descriptor), is_pid(Dest) ->
-    copy_opened_int(Source, Dest, Length, get_dtrace_utag());
+    copy_opened_int(Source, Dest, Length, 0);
 %% Copy between open raw files, both handled by the same module
 copy_int(#file_descriptor{module = Module} = Source,
 	 #file_descriptor{module = Module} = Dest,
@@ -743,14 +703,14 @@ copy_int(#file_descriptor{module = Module} = Source,
 %% Copy between open raw files of different modules
 copy_int(#file_descriptor{} = Source, 
 	 #file_descriptor{} = Dest, Length) ->
-    copy_opened_int(Source, Dest, Length, get_dtrace_utag());
+    copy_opened_int(Source, Dest, Length, 0);
 %% Copy between filenames, let the server do the copy
 copy_int({SourceName, SourceOpts}, {DestName, DestOpts}, Length) 
   when is_list(SourceOpts), is_list(DestOpts) ->
     check_and_call(copy, 
 		   [file_name(SourceName), SourceOpts,
 		    file_name(DestName), DestOpts,
-		    Length, get_dtrace_utag()]);
+		    Length]);
 %% Filename -> open file; must open Source and do client copy
 copy_int({SourceName, SourceOpts}, Dest, Length) 
   when is_list(SourceOpts), is_pid(Dest);
@@ -761,8 +721,7 @@ copy_int({SourceName, SourceOpts}, Dest, Length)
 	Source ->
 	    case open(Source, [read | SourceOpts]) of
 		{ok, Handle} ->
-		    Result = copy_opened_int(Handle, Dest, Length,
-                                             get_dtrace_utag()),
+		    Result = copy_opened_int(Handle, Dest, Length, 0),
 		    close(Handle),
 		    Result;
 		{error, _} = Error ->
@@ -779,8 +738,7 @@ copy_int(Source, {DestName, DestOpts}, Length)
 	Dest ->
 	    case open(Dest, [write | DestOpts]) of
 		{ok, Handle} ->
-		    Result = copy_opened_int(Source, Handle, Length,
-                                             get_dtrace_utag()),
+		    Result = copy_opened_int(Source, Handle, Length, 0),
 		    close(Handle),
 		    Result;
 		{error, _} = Error ->
@@ -815,46 +773,45 @@ copy_int(Source, Dest, Length) ->
 
 
 
-copy_opened(Source, Dest, Length, DTraceUtag)
+copy_opened(Source, Dest, Length)
   when is_integer(Length), Length >= 0;
        is_atom(Length) ->
-    copy_opened_int(Source, Dest, Length, DTraceUtag);
-copy_opened(_, _, _, _) ->
+    copy_opened_int(Source, Dest, Length);
+copy_opened(_, _, _) ->
     {error, badarg}.
 
 %% Here we know that Length is either an atom or an integer >= 0
 %% (by the way, atoms > integers)
 
-copy_opened_int(Source, Dest, Length, DTraceUtag)
+copy_opened_int(Source, Dest, Length)
   when is_pid(Source), is_pid(Dest) ->
-    copy_opened_int(Source, Dest, Length, 0, DTraceUtag);
-copy_opened_int(Source, Dest, Length, DTraceUtag)
+    copy_opened_int(Source, Dest, Length, 0);
+copy_opened_int(Source, Dest, Length)
   when is_pid(Source), is_record(Dest, file_descriptor) ->
-    copy_opened_int(Source, Dest, Length, 0, DTraceUtag);
-copy_opened_int(Source, Dest, Length, DTraceUtag)
+    copy_opened_int(Source, Dest, Length, 0);
+copy_opened_int(Source, Dest, Length)
   when is_record(Source, file_descriptor), is_pid(Dest) ->
-    copy_opened_int(Source, Dest, Length, 0, DTraceUtag);
-copy_opened_int(Source, Dest, Length, DTraceUtag)
+    copy_opened_int(Source, Dest, Length, 0);
+copy_opened_int(Source, Dest, Length)
   when is_record(Source, file_descriptor), is_record(Dest, file_descriptor) ->
-    copy_opened_int(Source, Dest, Length, 0, DTraceUtag);
-copy_opened_int(_, _, _, _) ->
+    copy_opened_int(Source, Dest, Length, 0);
+copy_opened_int(_, _, _) ->
     {error, badarg}.
 
 %% Here we know that Source and Dest are handles to open files, Length is
 %% as above, and Copied is an integer >= 0
 
 %% Copy loop in client process
-copy_opened_int(_, _, Length, Copied, _DTraceUtag)
-  when Length =< 0 -> % atom() > integer()
+copy_opened_int(_, _, Length, Copied) when Length =< 0 -> % atom() > integer()
     {ok, Copied};
-copy_opened_int(Source, Dest, Length, Copied, DTraceUtag) ->
+copy_opened_int(Source, Dest, Length, Copied) ->
     N = if Length > 65536 -> 65536; true -> Length end, % atom() > integer() !
-    case read(Source, N, DTraceUtag) of
+    case read(Source, N) of
 	{ok, Data} ->
 	    M = if is_binary(Data) -> byte_size(Data);
 		   is_list(Data)   -> length(Data)
 		end,
-	    case write(Dest, Data, DTraceUtag) of
+	    case write(Dest, Data) of
 		ok ->
 		    if M < N ->
 			    %% Got less than asked for - must be end of file
@@ -864,8 +821,7 @@ copy_opened_int(Source, Dest, Length, Copied, DTraceUtag) ->
 			    NewLength = if is_atom(Length) -> Length;
 					   true         -> Length-M
 					end,
-			    copy_opened_int(Source, Dest, NewLength, Copied+M,
-                                            DTraceUtag)
+			    copy_opened_int(Source, Dest, NewLength, Copied+M)
 		    end;
 		{error, _} = Error ->
 		    Error
@@ -885,8 +841,6 @@ copy_opened_int(Source, Dest, Length, Copied, DTraceUtag) ->
 
 ipread_s32bu_p32bu(File, Pos, MaxSize) when is_pid(File) ->
     ipread_s32bu_p32bu_int(File, Pos, MaxSize);
-ipread_s32bu_p32bu(#file_descriptor{module = prim_file = Module} = Handle, Pos, MaxSize) ->
-    Module:ipread_s32bu_p32bu(Handle, Pos, MaxSize, get_dtrace_utag());
 ipread_s32bu_p32bu(#file_descriptor{module = Module} = Handle, Pos, MaxSize) ->
     Module:ipread_s32bu_p32bu(Handle, Pos, MaxSize);
 ipread_s32bu_p32bu(_, _, _) ->
@@ -1467,7 +1421,10 @@ call(Command, Args) when is_list(Args) ->
 check_and_call(Command, Args) when is_list(Args) ->
     case check_args(Args) of
 	ok ->
-	    call(Command, Args);
+	    X = erlang:spread_utag(true),
+	    Y = call(Command, Args),
+	    erlang:restore_utag(X),
+	    Y;
 	Error ->
 	    Error
     end.
@@ -1502,6 +1459,3 @@ wait_file_reply(From, Ref) ->
 	    %% receive {'EXIT', From, _} -> ok after 0 -> ok end,
 	    {error, terminated}
     end.
-
-get_dtrace_utag() ->
-    dtrace:get_utag().
diff --git a/lib/kernel/src/file_io_server.erl b/lib/kernel/src/file_io_server.erl
index cc0343031b..14da9c1a55 100644
--- a/lib/kernel/src/file_io_server.erl
+++ b/lib/kernel/src/file_io_server.erl
@@ -21,7 +21,7 @@
 %% A simple file server for io to one file instance per server instance.
 
 -export([format_error/1]).
--export([start/4, start_link/4]).
+-export([start/3, start_link/3]).
 
 -export([count_and_find/3]).
 
@@ -43,18 +43,18 @@ format_error({_Line, Mod, Reason}) ->
 format_error(ErrorId) ->
     erl_posix_msg:message(ErrorId).
 
-start(Owner, FileName, ModeList, DTraceUtag)
+start(Owner, FileName, ModeList) 
   when is_pid(Owner), (is_list(FileName) orelse is_binary(FileName)), is_list(ModeList) ->
-    do_start(spawn, Owner, FileName, ModeList, DTraceUtag).
+    do_start(spawn, Owner, FileName, ModeList).
 
-start_link(Owner, FileName, ModeList, DTraceUtag)
+start_link(Owner, FileName, ModeList) 
   when is_pid(Owner), (is_list(FileName) orelse is_binary(FileName)), is_list(ModeList) ->
-    do_start(spawn_link, Owner, FileName, ModeList, DTraceUtag).
+    do_start(spawn_link, Owner, FileName, ModeList).
 
 %%%-----------------------------------------------------------------
 %%% Server starter, dispatcher and helpers
 
-do_start(Spawn, Owner, FileName, ModeList, DTraceUtag) ->
+do_start(Spawn, Owner, FileName, ModeList) ->
     Self = self(),
     Ref = make_ref(),
     Pid = 
@@ -63,12 +63,11 @@ do_start(Spawn, Owner, FileName, ModeList, DTraceUtag) ->
 		  %% process_flag(trap_exit, true),
 		  case parse_options(ModeList) of
 		      {ReadMode, UnicodeMode, Opts} ->
-			  case ?PRIM_FILE:open(FileName, Opts, DTraceUtag) of
+			  case ?PRIM_FILE:open(FileName, Opts) of
 			      {error, Reason} = Error ->
 				  Self ! {Ref, Error},
 				  exit(Reason);
 			      {ok, Handle} ->
-                                  put(dtrace_utag, DTraceUtag), % TODO: API?
 				  %% XXX must I handle R6 nodes here?
 				  M = erlang:monitor(process, Owner),
 				  Self ! {Ref, ok},
diff --git a/lib/kernel/src/file_server.erl b/lib/kernel/src/file_server.erl
index 82adc45795..fc6cd823c9 100644
--- a/lib/kernel/src/file_server.erl
+++ b/lib/kernel/src/file_server.erl
@@ -76,7 +76,6 @@ stop() ->
 
 init([]) ->
     process_flag(trap_exit, true),
-    put(dtrace_utag, atom_to_list(?FILE_SERVER)),
     case ?PRIM_FILE:start() of
 	{ok, Handle} ->
 	    ets:new(?FILE_IO_SERVER_TABLE, [named_table]),
@@ -100,9 +99,9 @@ init([]) ->
 	{'reply', 'eof' | 'ok' | {'error', term()} | {'ok', term()}, state()} |
 	{'stop', 'normal', 'stopped', state()}.
 
-handle_call({open, Name, ModeList, DTraceUtag}, {Pid, _Tag} = _From, Handle)
+handle_call({open, Name, ModeList}, {Pid, _Tag} = _From, Handle)
   when is_list(ModeList) ->
-    Child = ?FILE_IO_SERVER:start_link(Pid, Name, ModeList, DTraceUtag),
+    Child = ?FILE_IO_SERVER:start_link(Pid, Name, ModeList),
     case Child of
 	{ok, P} when is_pid(P) ->
 	    ets:insert(?FILE_IO_SERVER_TABLE, {P, Name});
@@ -111,86 +110,87 @@ handle_call({open, Name, ModeList, DTraceUtag}, {Pid, _Tag} = _From, Handle)
     end,
     {reply, Child, Handle};
 
-handle_call({open, _Name, _Mode, _DTraceUtag}, _From, Handle) ->
+handle_call({open, _Name, _Mode}, _From, Handle) ->
     {reply, {error, einval}, Handle};
 
-handle_call({read_file, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:read_file(Name, DTraceUtag), Handle};
+handle_call({read_file, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:read_file(Name), Handle};
 
-handle_call({write_file, Name, Bin, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:write_file(Name, Bin, DTraceUtag), Handle};
+handle_call({write_file, Name, Bin}, _From, Handle) ->
+    {reply, ?PRIM_FILE:write_file(Name, Bin), Handle};
 
-handle_call({set_cwd, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:set_cwd(Handle, Name, DTraceUtag), Handle};
+handle_call({set_cwd, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:set_cwd(Handle, Name), Handle};
 
-handle_call({delete, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:delete(Handle, Name, DTraceUtag), Handle};
+handle_call({delete, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:delete(Handle, Name), Handle};
 
-handle_call({rename, Fr, To, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:rename(Handle, Fr, To, DTraceUtag), Handle};
+handle_call({rename, Fr, To}, _From, Handle) ->
+    {reply, ?PRIM_FILE:rename(Handle, Fr, To), Handle};
 
-handle_call({make_dir, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:make_dir(Handle, Name, DTraceUtag), Handle};
+handle_call({make_dir, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:make_dir(Handle, Name), Handle};
 
-handle_call({del_dir, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:del_dir(Handle, Name, DTraceUtag), Handle};
+handle_call({del_dir, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:del_dir(Handle, Name), Handle};
 
-handle_call({list_dir, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:list_dir(Handle, Name, DTraceUtag), Handle};
+handle_call({list_dir, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:list_dir(Handle, Name), Handle};
 
 handle_call(get_cwd, _From, Handle) ->
-    {reply, ?PRIM_FILE:get_cwd(Handle, no_drive, "TODO-fixme"), Handle};
-handle_call({get_cwd, no_drive, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:get_cwd(Handle, no_drive, DTraceUtag), Handle};
-handle_call({get_cwd, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:get_cwd(Handle, Name, DTraceUtag), Handle};
+    {reply, ?PRIM_FILE:get_cwd(Handle), Handle};
+handle_call({get_cwd}, _From, Handle) ->
+    {reply, ?PRIM_FILE:get_cwd(Handle), Handle};
+handle_call({get_cwd, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:get_cwd(Handle, Name), Handle};
 
-handle_call({read_file_info, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:read_file_info(Handle, Name, [], DTraceUtag), Handle};
-handle_call({read_file_info, Name, Opts, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:read_file_info(Handle, Name, Opts, DTraceUtag), Handle};
+handle_call({read_file_info, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:read_file_info(Handle, Name), Handle};
 
-handle_call({altname, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:altname(Handle, Name, DTraceUtag), Handle};
+handle_call({read_file_info, Name, Opts}, _From, Handle) ->
+    {reply, ?PRIM_FILE:read_file_info(Handle, Name, Opts), Handle};
 
-handle_call({write_file_info, Name, Info, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:write_file_info(Handle, Name, Info, [], DTraceUtag), Handle};
-handle_call({write_file_info, Name, Info, Opts, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:write_file_info(Handle, Name, Info, Opts, DTraceUtag), Handle};
+handle_call({altname, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:altname(Handle, Name), Handle};
 
-handle_call({read_link_info, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:read_link_info(Handle, Name, [], DTraceUtag), Handle};
-handle_call({read_link_info, Name, Opts, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:read_link_info(Handle, Name, Opts, DTraceUtag), Handle};
+handle_call({write_file_info, Name, Info}, _From, Handle) ->
+    {reply, ?PRIM_FILE:write_file_info(Handle, Name, Info), Handle};
 
-handle_call({read_link, Name, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:read_link(Handle, Name, DTraceUtag), Handle};
+handle_call({write_file_info, Name, Info, Opts}, _From, Handle) ->
+    {reply, ?PRIM_FILE:write_file_info(Handle, Name, Info, Opts), Handle};
 
-handle_call({make_link, Old, New, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:make_link(Handle, Old, New, DTraceUtag), Handle};
+handle_call({read_link_info, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:read_link_info(Handle, Name), Handle};
 
-handle_call({make_symlink, Old, New, DTraceUtag}, _From, Handle) ->
-    {reply, ?PRIM_FILE:make_symlink(Handle, Old, New, DTraceUtag), Handle};
+handle_call({read_link_info, Name, Opts}, _From, Handle) ->
+    {reply, ?PRIM_FILE:read_link_info(Handle, Name, Opts), Handle};
 
-handle_call({copy, SourceName, SourceOpts, DestName, DestOpts, Length, DTraceUtag},
+handle_call({read_link, Name}, _From, Handle) ->
+    {reply, ?PRIM_FILE:read_link(Handle, Name), Handle};
+
+handle_call({make_link, Old, New}, _From, Handle) ->
+    {reply, ?PRIM_FILE:make_link(Handle, Old, New), Handle};
+
+handle_call({make_symlink, Old, New}, _From, Handle) ->
+    {reply, ?PRIM_FILE:make_symlink(Handle, Old, New), Handle};
+
+handle_call({copy, SourceName, SourceOpts, DestName, DestOpts, Length},
 	    _From, Handle) ->
     Reply = 
-	case ?PRIM_FILE:open(SourceName, [read, binary | SourceOpts],
-                             DTraceUtag) of
+	case ?PRIM_FILE:open(SourceName, [read, binary | SourceOpts]) of
 	    {ok, Source} ->
 		SourceReply = 
 		    case ?PRIM_FILE:open(DestName, 
-					 [write, binary | DestOpts],
-                                         DTraceUtag) of
+					 [write, binary | DestOpts]) of
 			{ok, Dest} ->
 			    DestReply = 
-				?PRIM_FILE:copy(Source, Dest, Length, DTraceUtag),
-			    ?PRIM_FILE:close(Dest, DTraceUtag),
+				?PRIM_FILE:copy(Source, Dest, Length),
+			    ?PRIM_FILE:close(Dest),
 			    DestReply;
 			{error, _} = Error ->
 			    Error
 		    end,
-		?PRIM_FILE:close(Source, DTraceUtag),
+		?PRIM_FILE:close(Source),
 		SourceReply;
 	    {error, _} = Error ->
 		Error