From 9b93df1788a1c0ed30f8715fed43d0d114c36969 Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Tue, 5 Jan 2016 17:10:44 -0800
Subject: [PATCH] sys: FspIoqNextPendingIrp: add BoundaryIrp parameter

---
 src/sys/driver.h |  2 +-
 src/sys/ioq.c    |  8 ++++++--
 src/sys/volume.c | 18 ++++++++++++++----
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/src/sys/driver.h b/src/sys/driver.h
index adb60b85..0d590f7d 100644
--- a/src/sys/driver.h
+++ b/src/sys/driver.h
@@ -359,7 +359,7 @@ VOID FspIoqStop(FSP_IOQ *Ioq);
 BOOLEAN FspIoqStopped(FSP_IOQ *Ioq);
 VOID FspIoqRemoveExpired(FSP_IOQ *Ioq);
 BOOLEAN FspIoqPostIrpEx(FSP_IOQ *Ioq, PIRP Irp, BOOLEAN CheckCapacity, NTSTATUS *PResult);
-PIRP FspIoqNextPendingIrp(FSP_IOQ *Ioq, PLARGE_INTEGER Timeout);
+PIRP FspIoqNextPendingIrp(FSP_IOQ *Ioq, PIRP BoundaryIrp, PLARGE_INTEGER Timeout);
 BOOLEAN FspIoqStartProcessingIrp(FSP_IOQ *Ioq, PIRP Irp);
 PIRP FspIoqEndProcessingIrp(FSP_IOQ *Ioq, UINT_PTR IrpHint);
 
diff --git a/src/sys/ioq.c b/src/sys/ioq.c
index 6cc91148..69131675 100644
--- a/src/sys/ioq.c
+++ b/src/sys/ioq.c
@@ -107,7 +107,11 @@ static PIRP FspIoqPendingPeekNextIrp(PIO_CSQ IoCsq, PIRP Irp, PVOID PeekContext)
         return FspIrpTimestamp(Irp) <= ExpirationTime ? Irp : 0;
     }
     else
+    {
+        if (Irp == IrpHint)
+            return 0;
         return Irp;
+    }
 }
 
 _IRQL_raises_(DISPATCH_LEVEL)
@@ -311,7 +315,7 @@ BOOLEAN FspIoqPostIrpEx(FSP_IOQ *Ioq, PIRP Irp, BOOLEAN CheckCapacity, NTSTATUS
     return FALSE;
 }
 
-PIRP FspIoqNextPendingIrp(FSP_IOQ *Ioq, PLARGE_INTEGER Timeout)
+PIRP FspIoqNextPendingIrp(FSP_IOQ *Ioq, PIRP BoundaryIrp, PLARGE_INTEGER Timeout)
 {
     /* timeout of 0 normally means infinite wait; for us it means do not do any wait at all! */
     if (0 != Timeout)
@@ -324,7 +328,7 @@ PIRP FspIoqNextPendingIrp(FSP_IOQ *Ioq, PLARGE_INTEGER Timeout)
             return FspIoqTimeout;
     }
     FSP_IOQ_PEEK_CONTEXT PeekContext;
-    PeekContext.IrpHint = (PVOID)1;
+    PeekContext.IrpHint = 0 != BoundaryIrp ? BoundaryIrp : (PVOID)1;
     PeekContext.ExpirationTime = 0;
     return IoCsqRemoveNextIrp(&Ioq->PendingIoCsq, &PeekContext);
 }
diff --git a/src/sys/volume.c b/src/sys/volume.c
index e4cb25a0..df07099e 100644
--- a/src/sys/volume.c
+++ b/src/sys/volume.c
@@ -510,7 +510,7 @@ NTSTATUS FspVolumeTransact(
     PUINT8 BufferEnd;
     FSP_FSCTL_TRANSACT_RSP *Response, *NextResponse;
     FSP_FSCTL_TRANSACT_REQ *Request, *PendingIrpRequest;
-    PIRP ProcessIrp, PendingIrp;
+    PIRP ProcessIrp, PendingIrp, RepostedIrp = 0;
     LARGE_INTEGER Timeout;
 
     /* process any user-mode file system responses */
@@ -545,7 +545,7 @@ NTSTATUS FspVolumeTransact(
     KeQuerySystemTime(&Timeout);
     Timeout.QuadPart += FsvolDeviceExtension->VolumeParams.TransactTimeout * 10000;
         /* convert millis to nanos and add to absolute time */
-    while (0 == (PendingIrp = FspIoqNextPendingIrp(FsvolDeviceExtension->Ioq, &Timeout)))
+    while (0 == (PendingIrp = FspIoqNextPendingIrp(FsvolDeviceExtension->Ioq, 0, &Timeout)))
     {
         if (FspIoqStopped(FsvolDeviceExtension->Ioq))
             return STATUS_CANCELLED;
@@ -565,7 +565,16 @@ NTSTATUS FspVolumeTransact(
         PendingIrpRequest = FspIrpRequest(PendingIrp);
 
         Result = FspIopDispatchPrepare(PendingIrp, PendingIrpRequest);
-        if (!NT_SUCCESS(Result))
+        if (STATUS_PENDING == Result)
+        {
+            /*
+             * The IRP has been reposted to our Ioq. Remember the first such IRP,
+             * so that we know to break the loop if we see it again.
+             */
+            if (0 == RepostedIrp)
+                RepostedIrp = PendingIrp;
+        }
+        else if (!NT_SUCCESS(Result))
             FspIopCompleteIrp(PendingIrp, Result);
         else
         {
@@ -590,7 +599,8 @@ NTSTATUS FspVolumeTransact(
                 break;
         }
 
-        PendingIrp = FspIoqNextPendingIrp(FsvolDeviceExtension->Ioq, 0);
+        /* get the next pending IRP, but do not go beyond the first reposted IRP! */
+        PendingIrp = FspIoqNextPendingIrp(FsvolDeviceExtension->Ioq, RepostedIrp, 0);
         if (0 == PendingIrp)
             break;
     }