01/01: [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.

[Pierre Schweitzer]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=a6e080bd3db21d64f1b432...

commit a6e080bd3db21d64f1b43222377bb9c70e805857
Author:     Pierre Schweitzer [e-mail]
AuthorDate: Fri Feb 9 21:52:41 2018 +0100
Commit:     Pierre Schweitzer [e-mail]
CommitDate: Fri Feb 9 21:52:41 2018 +0100

[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.
---
 ntoskrnl/cc/view.c             | 19 +++++++++++++++++--
 ntoskrnl/include/internal/cc.h |  1 +
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/ntoskrnl/cc/view.c b/ntoskrnl/cc/view.c
index d69b195c10..cf2d2c5cb7 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 d34360a7e3..5751ab665e 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;