From a910385cb19b406ec1c3cc51f80697d1787ee8b8 Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Tue, 13 Nov 2018 10:11:39 -0800
Subject: [PATCH 1/2] dll: ensure FspFileSystemFinalize is called

---
 src/dll/library.c | 1 +
 src/dll/library.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/src/dll/library.c b/src/dll/library.c
index 4d755b1c..69bd91ae 100644
--- a/src/dll/library.c
+++ b/src/dll/library.c
@@ -46,6 +46,7 @@ BOOL WINAPI DllMain(HINSTANCE Instance, DWORD Reason, PVOID Reserved)
         Dynamic = 0 == Reserved;
         fsp_fuse_finalize(Dynamic);
         FspServiceFinalize(Dynamic);
+        FspFileSystemFinalize(Dynamic);
         FspEventLogFinalize(Dynamic);
         FspPosixFinalize(Dynamic);
         FspWksidFinalize(Dynamic);
diff --git a/src/dll/library.h b/src/dll/library.h
index 66018d72..0c86ded7 100644
--- a/src/dll/library.h
+++ b/src/dll/library.h
@@ -47,6 +47,7 @@
 VOID FspWksidFinalize(BOOLEAN Dynamic);
 VOID FspPosixFinalize(BOOLEAN Dynamic);
 VOID FspEventLogFinalize(BOOLEAN Dynamic);
+VOID FspFileSystemFinalize(BOOLEAN Dynamic);
 VOID FspServiceFinalize(BOOLEAN Dynamic);
 VOID fsp_fuse_finalize(BOOLEAN Dynamic);
 VOID fsp_fuse_finalize_thread(VOID);

From 5d90c35e2083bd1cc3753166ef6301dfdfe983cf Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Wed, 21 Nov 2018 15:32:25 -0800
Subject: [PATCH 2/2] sys: FspFsvrtDeviceControl: STATUS_UNRECOGNIZED_VOLUME

This fixes GitHub issue #177. All credit for the investigation and
suggested workaround goes to @thinkport.
---
 src/sys/devctl.c | 27 +++++++++++++++++++++++++++
 src/sys/driver.c | 15 +++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/sys/devctl.c b/src/sys/devctl.c
index 14de171c..d6d24568 100644
--- a/src/sys/devctl.c
+++ b/src/sys/devctl.c
@@ -21,6 +21,8 @@
 
 #include <sys/driver.h>
 
+static NTSTATUS FspFsvrtDeviceControl(
+    PDEVICE_OBJECT DeviceObject, PIRP Irp, PIO_STACK_LOCATION IrpSp);
 static NTSTATUS FspFsvolDeviceControl(
     PDEVICE_OBJECT DeviceObject, PIRP Irp, PIO_STACK_LOCATION IrpSp);
 FSP_IOCMPL_DISPATCH FspFsvolDeviceControlComplete;
@@ -28,6 +30,7 @@ static FSP_IOP_REQUEST_FINI FspFsvolDeviceControlRequestFini;
 FSP_DRIVER_DISPATCH FspDeviceControl;
 
 #ifdef ALLOC_PRAGMA
+#pragma alloc_text(PAGE, FspFsvrtDeviceControl)
 #pragma alloc_text(PAGE, FspFsvolDeviceControl)
 #pragma alloc_text(PAGE, FspFsvolDeviceControlComplete)
 #pragma alloc_text(PAGE, FspFsvolDeviceControlRequestFini)
@@ -39,6 +42,28 @@ enum
     RequestFileNode                     = 0,
 };
 
+static NTSTATUS FspFsvrtDeviceControl(
+    PDEVICE_OBJECT FsvolDeviceObject, PIRP Irp, PIO_STACK_LOCATION IrpSp)
+{
+    PAGED_CODE();
+
+    /*
+     * Fix GitHub issue #177. All credit for the investigation of this issue
+     * and the suggested steps to reproduce and work around the problem goes
+     * to GitHub user @thinkport.
+     *
+     * When Windows attempts to mount a new volume it iterates over all disk file
+     * systems registered with IoRegisterFileSystem. Foreign (i.e. non-WinFsp) file
+     * systems would in some cases attempt to mount our Fsvrt volume device by
+     * sending it unknown IOCTL codes, which would then be failed with
+     * STATUS_INVALID_DEVICE_REQUEST. Unfortunately the file systems would then
+     * report this error code to the I/O Manager, which would cause it to abort the
+     * mounting process completely and thus WinFsp would never get a chance to
+     * mount its own volume device!
+     */
+    return STATUS_UNRECOGNIZED_VOLUME;
+}
+
 static NTSTATUS FspFsvolDeviceControl(
     PDEVICE_OBJECT FsvolDeviceObject, PIRP Irp, PIO_STACK_LOCATION IrpSp)
 {
@@ -155,6 +180,8 @@ NTSTATUS FspDeviceControl(
     {
     case FspFsvolDeviceExtensionKind:
         FSP_RETURN(Result = FspFsvolDeviceControl(DeviceObject, Irp, IrpSp));
+    case FspFsvrtDeviceExtensionKind:
+        FSP_RETURN(Result = FspFsvrtDeviceControl(DeviceObject, Irp, IrpSp));
     default:
         FSP_RETURN(Result = STATUS_INVALID_DEVICE_REQUEST);
     }
diff --git a/src/sys/driver.c b/src/sys/driver.c
index ffab176f..558b93ae 100644
--- a/src/sys/driver.c
+++ b/src/sys/driver.c
@@ -169,6 +169,21 @@ NTSTATUS DriverEntry(
         &FspFsmupDeviceObject);
     if (!NT_SUCCESS(Result))
         goto exit;
+
+#if DBG
+    /*
+     * Fix GitHub issue #177. All credit for the investigation of this issue
+     * and the suggested steps to reproduce and work around the problem goes
+     * to GitHub user @thinkport.
+     *
+     * On debug builds set DO_LOW_PRIORITY_FILESYSTEM to place the file system
+     * at the end of the file system list during IoRegisterFileSystem below.
+     * This allows us to test the behavior of our Fsvrt devices when foreign
+     * file systems attempt to use them for mounting.
+     */
+    SetFlag(FspFsctlDiskDeviceObject->Flags, DO_LOW_PRIORITY_FILESYSTEM);
+#endif
+
     Result = FspDeviceInitialize(FspFsctlDiskDeviceObject);
     ASSERT(STATUS_SUCCESS == Result);
     Result = FspDeviceInitialize(FspFsctlNetDeviceObject);