nbd: pass the fd to tapdisk if the control socket exists, otherwise u…

…se vhd-tool Signed-off-by: David Scott <dave.scott@eu.citrix.com>
djs55 · Oct 24, 2013 · b8a6932 · b8a6932
1 parent 05efc0e
commit b8a6932
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Showing 4 changed files with 74 additions and 44 deletions.
diff --git a/ocaml/xapi/OMakefile b/ocaml/xapi/OMakefile
@@ -38,7 +38,7 @@ OCamlProgram(sparse_dd, sparse_dd sparse_encoding ../util/stats)
 OCamlProgram(show_bat, show_bat)
 #OCamlProgram(monitor_fake_plugin, monitor_fake_plugin rrdd_fake_common rrd)
 
-OCamlProgram(storage_impl_test, sparse_encoding sparse_dd_wrapper ../xenops/updates storage_migrate storage_impl ../xenops/task_server storage_task storage_locks storage_impl_test)
+OCamlProgram(storage_impl_test, sparse_encoding sparse_dd_wrapper ../xenops/updates vhd_tool_wrapper storage_migrate storage_impl ../xenops/task_server storage_task storage_locks storage_impl_test)
 
 OCamlProgram(cancel_tests, cancel_tests ../xenops/xenops_helpers)
 
@@ -78,6 +78,7 @@ XAPI_MODULES = $(COMMON) \
 	storage_task \
 	storage_access \
 	storage_mux \
+	vhd_tool_wrapper \
 	storage_migrate \
 	storage_proxy \
 	storage_utils \

diff --git a/ocaml/xapi/import_raw_vdi.ml b/ocaml/xapi/import_raw_vdi.ml
@@ -25,31 +25,6 @@ open Unixext
 open Pervasiveext
 open Client
 
-let vhd_tool = "/usr/sbin/vhd-tool"
-
-let receive protocol (s: Unix.file_descr) (path: string) =
-  let s' = Uuidm.to_string (Uuidm.create `V4) in
-  let args = [ "serve";
-               "--direct";
-               "--source-protocol"; protocol;
-               "--source-fd"; s';
-               "--destination"; "file://" ^ path;
-               "--destination-format"; "raw" ] in
-  info "Executing %s %s" vhd_tool (String.concat " " args);
-  let open Forkhelpers in
-  match with_logfile_fd "vhd-tool"
-    (fun log_fd ->
-      let pid = safe_close_and_exec None (Some log_fd) (Some log_fd) [ s', s ] vhd_tool args in
-      let (_, status) = waitpid pid in
-      if status <> Unix.WEXITED 0 then begin
-        error "vhd-tool failed, returning VDI_IO_ERROR";
-        raise (Api_errors.Server_error (Api_errors.vdi_io_error, ["Device I/O errors"])) 
-      end
-    ) with
-  | Success(out, _) -> debug "%s" out
-  | Failure(out, e) -> error "vhd-tool output: %s" out; raise e
-
-
 let localhost_handler rpc session_id vdi (req: Request.t) (s: Unix.file_descr) =
   req.Request.close <- true;
   Xapi_http.with_context "Importing raw VDI" req s
@@ -74,8 +49,8 @@ let localhost_handler rpc session_id vdi (req: Request.t) (s: Unix.file_descr) =
 				   content_type ] in
                Http_svr.headers s headers;
 			     if chunked
-			     then receive "chunked" s path
-			     else receive "none" s path
+			     then Vhd_tool_wrapper.receive "chunked" s path
+			     else Vhd_tool_wrapper.receive "none" s path
 		   )
 	    );
 	    TaskHelper.complete ~__context None;

diff --git a/ocaml/xapi/storage_migrate.ml b/ocaml/xapi/storage_migrate.ml
@@ -572,30 +572,39 @@ let post_detach_hook ~sr ~vdi ~dp =
 				Opt.iter (fun id -> Updates.Scheduler.cancel id) r.watchdog;
 				debug "Created thread %d to call receive finalize and dp destroy" (Thread.id t))
 
+let tapdisk_control_socket pid minor =
+	Printf.sprintf "/var/run/blktap-control/nbdserver%d.%d" pid minor
+
+let hand_fd_to_tapdisk s pid minor dp =
+	debug "attempting to transfer NBD fd to existing tapdisk (pid %d; minor %d)" pid minor;
+	let path = tapdisk_control_socket pid minor in
+	let control_fd = Unix.socket Unix.PF_UNIX Unix.SOCK_STREAM 0 in
+	finally
+		(fun () ->
+			Unix.connect control_fd (Unix.ADDR_UNIX path);
+			let msg = dp in
+			let len = String.length msg in
+			let written = Unixext.send_fd control_fd msg 0 len [] s in
+			if written <> len then begin
+				error "Failed to transfer fd to %s" path;
+				failwith "failed to transfer fd to tapdisk"
+			end;
+		)
+		(fun () -> Unix.close control_fd)
+
 let nbd_handler req s sr vdi dp =
 	debug "sr=%s vdi=%s dp=%s" sr vdi dp;
 	let attach_info = Local.DP.attach_info ~dbg:"nbd" ~sr ~vdi ~dp in
         req.Http.Request.close <- true;
 	match tapdisk_of_attach_info attach_info with
 		| Some tapdev ->
+			Http_svr.headers s (Http.http_200_ok () @ ["Transfer-encoding: nbd"]);
 			let minor = Tapctl.get_minor tapdev in
 			let pid = Tapctl.get_tapdisk_pid tapdev in
-			let path = Printf.sprintf "/var/run/blktap-control/nbdserver%d.%d" pid minor in
-			Http_svr.headers s (Http.http_200_ok () @ ["Transfer-encoding: nbd"]);
-			let control_fd = Unix.socket Unix.PF_UNIX Unix.SOCK_STREAM 0 in
-			finally
-				(fun () ->
-					Unix.connect control_fd (Unix.ADDR_UNIX path);
-					let msg = dp in
-					let len = String.length msg in
-					let written = Unixext.send_fd control_fd msg 0 len [] s in
-					if written <> len then begin
-						error "Failed to transfer fd to %s" path;
-						Http_svr.headers s (Http.http_404_missing ~version:"1.0" ());
-						req.Http.Request.close <- true
-					end;
-				)
-				(fun () -> Unix.close control_fd)
+			let path = tapdisk_control_socket pid minor in
+			if Sys.file_exists path
+			then hand_fd_to_tapdisk s pid minor dp
+			else Vhd_tool_wrapper.receive "nbd" s attach_info.params
 		| None -> 
 			()
 

diff --git a/ocaml/xapi/vhd_tool_wrapper.ml b/ocaml/xapi/vhd_tool_wrapper.ml
@@ -0,0 +1,45 @@
+(*
+ * Copyright (C) 2006-2009 Citrix Systems Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *)
+(** HTTP handler for importing a raw VDI.
+ * @group Import and Export
+ *)
+
+module D=Debug.Make(struct let name="vdi_tool_wrapper" end)
+open D
+
+let vhd_tool = "/usr/bin/vhd-tool"
+
+let receive protocol (s: Unix.file_descr) (path: string) =
+  let s' = Uuidm.to_string (Uuidm.create `V4) in
+  let args = [ "serve";
+               "--direct";
+               "--source-protocol"; protocol;
+               "--source-fd"; s';
+               "--destination"; "file://" ^ path;
+               "--destination-format"; "raw" ] in
+  info "Executing %s %s" vhd_tool (String.concat " " args);
+  let open Forkhelpers in
+  match with_logfile_fd "vhd-tool"
+    (fun log_fd ->
+      let pid = safe_close_and_exec None (Some log_fd) (Some log_fd) [ s', s ] vhd_tool args in
+      let (_, status) = waitpid pid in
+      if status <> Unix.WEXITED 0 then begin
+        error "vhd-tool failed, returning VDI_IO_ERROR";
+        raise (Api_errors.Server_error (Api_errors.vdi_io_error, ["Device I/O errors"])) 
+      end
+    ) with
+  | Success(out, _) -> debug "%s" out
+  | Failure(out, e) -> error "vhd-tool output: %s" out; raise e
+
+