From a7a526351f24913bbde64bf84fe7421d17d94edd Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Thu, 9 Jun 2022 10:07:43 +0100
Subject: [PATCH] sys: keep extra fsvol device reference

Reference an fsvol device at CREATE time and dereference at CLOSE time,
to ensure that fsvol remains around for DeviceIoControl operations done
after CLEANUP.
---
 src/sys/close.c  | 3 +++
 src/sys/create.c | 4 ++++
 src/sys/volume.c | 1 -
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/sys/close.c b/src/sys/close.c
index 7e146536..b92d6e42 100644
--- a/src/sys/close.c
+++ b/src/sys/close.c
@@ -43,6 +43,9 @@ static NTSTATUS FspFsctlClose(
 {
     PAGED_CODE();
 
+    if (0 != IrpSp->FileObject->FsContext2)
+        FspDeviceDereference(IrpSp->FileObject->FsContext2);
+
     Irp->IoStatus.Information = 0;
     return STATUS_SUCCESS;
 }
diff --git a/src/sys/create.c b/src/sys/create.c
index 03e47806..34303256 100644
--- a/src/sys/create.c
+++ b/src/sys/create.c
@@ -116,7 +116,11 @@ static NTSTATUS FspFsctlCreate(
     if (0 == FileObject->RelatedFileObject &&
         PREFIXW_SIZE <= FileObject->FileName.Length &&
         RtlEqualMemory(PREFIXW, FileObject->FileName.Buffer, PREFIXW_SIZE))
+    {
         Result = FspVolumeCreate(DeviceObject, Irp, IrpSp);
+        if (NT_SUCCESS(Result) && 0 != IrpSp->FileObject->FsContext2)
+            FspDeviceReference(IrpSp->FileObject->FsContext2);
+    }
     else
     {
         Result = STATUS_SUCCESS;
diff --git a/src/sys/volume.c b/src/sys/volume.c
index 7cd87654..6928d065 100644
--- a/src/sys/volume.c
+++ b/src/sys/volume.c
@@ -417,7 +417,6 @@ static VOID FspVolumeDeleteNoLock(
 
     PDEVICE_OBJECT FsvolDeviceObject = IrpSp->FileObject->FsContext2;
     FSP_FSVOL_DEVICE_EXTENSION *FsvolDeviceExtension = FspFsvolDeviceExtension(FsvolDeviceObject);
-    IrpSp->FileObject->FsContext2 = 0;
 
     /* stop the I/O queue */
     FspIoqStop(FsvolDeviceExtension->Ioq, TRUE);