From: Pierre Schweitzer <pierre@reactos.org>
Date: Fri, 9 Feb 2018 20:52:41 +0000 (+0100)
Subject: [NTOSKRNL] Avoid private cache map allocation for the first handle
X-Git-Tag: 0.4.9-dev~43
X-Git-Url: https://git.reactos.org/?p=reactos.git;a=commitdiff_plain;h=a6e080bd3db21d64f1b43222377bb9c70e805857

[NTOSKRNL] Avoid private cache map allocation for the first handle
Standard shared cache map provides space for a private cache map, do the same
and make it available for the first handle. It avoids two allocations in a row.
---

diff --git a/ntoskrnl/cc/view.c b/ntoskrnl/cc/view.c
index d69b195c109..cf2d2c5cb75 100644
--- a/ntoskrnl/cc/view.c
+++ b/ntoskrnl/cc/view.c
@@ -1194,7 +1194,14 @@ CcRosReleaseFileCache (
             KeReleaseSpinLock(&SharedCacheMap->CacheMapLock, OldIrql);
 
             /* And free it. */
-            ExFreePoolWithTag(PrivateMap, TAG_PRIVATE_CACHE_MAP);
+            if (PrivateMap != &SharedCacheMap->PrivateCacheMap)
+            {
+                ExFreePoolWithTag(PrivateMap, TAG_PRIVATE_CACHE_MAP);
+            }
+            else
+            {
+                PrivateMap->NodeTypeCode = 0;
+            }
 
             if (SharedCacheMap->OpenCount > 0)
             {
@@ -1271,7 +1278,15 @@ CcRosInitializeFileCache (
         PPRIVATE_CACHE_MAP PrivateMap;
 
         /* Allocate the private cache map for this handle */
-        PrivateMap = ExAllocatePoolWithTag(NonPagedPool, sizeof(PRIVATE_CACHE_MAP), TAG_PRIVATE_CACHE_MAP);
+        if (SharedCacheMap->PrivateCacheMap.NodeTypeCode != 0)
+        {
+            PrivateMap = ExAllocatePoolWithTag(NonPagedPool, sizeof(PRIVATE_CACHE_MAP), TAG_PRIVATE_CACHE_MAP);
+        }
+        else
+        {
+            PrivateMap = &SharedCacheMap->PrivateCacheMap;
+        }
+
         if (PrivateMap == NULL)
         {
             /* If we also allocated the shared cache map for this file, kill it */
diff --git a/ntoskrnl/include/internal/cc.h b/ntoskrnl/include/internal/cc.h
index d34360a7e35..5751ab665e3 100644
--- a/ntoskrnl/include/internal/cc.h
+++ b/ntoskrnl/include/internal/cc.h
@@ -169,6 +169,7 @@ typedef struct _ROS_SHARED_CACHE_MAP
     PVOID LazyWriteContext;
     LIST_ENTRY PrivateList;
     ULONG DirtyPageThreshold;
+    PRIVATE_CACHE_MAP PrivateCacheMap;
 
     /* ROS specific */
     LIST_ENTRY CacheMapVacbListHead;