From 469e15c7ae5d2b7dc266fdde7beb173d8263d563 Mon Sep 17 00:00:00 2001
From: Pierre Schweitzer <pierre@reactos.org>
Date: Sun, 26 Aug 2018 21:49:05 +0200
Subject: [PATCH] [NTOSKRNL] Stubplement CcPinMappedData() and simplify
 CcPinRead()

It's based on the code that was in CcPinRead() implementation. This
made no sense to have CcPinMappedData() doing nothing while implementing
everything in CcPinRead(). Indeed, drivers (starting with MS drivers)
can map data first and pin it afterwards with CcPinMappedData(). It was
leading to incorrect behavior with our previous noop implementation.
---
 ntoskrnl/cc/pin.c | 55 ++++++++++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/ntoskrnl/cc/pin.c b/ntoskrnl/cc/pin.c
index 2d48a27a0aa..8b99b8c2108 100644
--- a/ntoskrnl/cc/pin.c
+++ b/ntoskrnl/cc/pin.c
@@ -161,6 +161,7 @@ CcPinMappedData (
     IN	ULONG Flags,
     OUT	PVOID * Bcb)
 {
+    PINTERNAL_BCB iBcb;
     PROS_SHARED_CACHE_MAP SharedCacheMap;
 
     CCTRACE(CC_API_DEBUG, "FileOffset=%p FileOffset=%p Length=%lu Flags=0x%lx\n",
@@ -174,7 +175,21 @@ CcPinMappedData (
     ASSERT(SharedCacheMap);
     ASSERT(SharedCacheMap->PinAccess);
 
-    /* no-op for current implementation. */
+    iBcb = *Bcb;
+    ASSERT(iBcb->Pinned == FALSE);
+
+    iBcb->Pinned = TRUE;
+    iBcb->Vacb->PinCount++;
+
+    if (Flags & PIN_EXCLUSIVE)
+    {
+        ExAcquireResourceExclusiveLite(&iBcb->Lock, TRUE);
+    }
+    else
+    {
+        ExAcquireResourceSharedLite(&iBcb->Lock, TRUE);
+    }
+
     return TRUE;
 }
 
@@ -191,8 +206,6 @@ CcPinRead (
     OUT	PVOID * Bcb,
     OUT	PVOID * Buffer)
 {
-    PINTERNAL_BCB iBcb;
-
     CCTRACE(CC_API_DEBUG, "FileOffset=%p FileOffset=%p Length=%lu Flags=0x%lx\n",
         FileObject, FileOffset, Length, Flags);
 
@@ -205,32 +218,20 @@ CcPinRead (
         ++CcPinReadNoWait;
     }
 
-    if (CcMapData(FileObject, FileOffset, Length, Flags, Bcb, Buffer))
+    /* Map first */
+    if (!CcMapData(FileObject, FileOffset, Length, Flags, Bcb, Buffer))
     {
-        if (CcPinMappedData(FileObject, FileOffset, Length, Flags, Bcb))
-        {
-            iBcb = *Bcb;
-
-            ASSERT(iBcb->Pinned == FALSE);
-
-            iBcb->Pinned = TRUE;
-            iBcb->Vacb->PinCount++;
-
-            if (Flags & PIN_EXCLUSIVE)
-            {
-                ExAcquireResourceExclusiveLite(&iBcb->Lock, TRUE);
-            }
-            else
-            {
-                ExAcquireResourceSharedLite(&iBcb->Lock, TRUE);
-            }
-
-            return TRUE;
-        }
-        else
-            CcUnpinData(*Bcb);
+        return FALSE;
     }
-    return FALSE;
+
+    /* Pin then */
+    if (!CcPinMappedData(FileObject, FileOffset, Length, Flags, Bcb))
+    {
+        CcUnpinData(*Bcb);
+        return FALSE;
+    }
+
+    return TRUE;
 }
 
 /*