[NTOS:CC] Rewrite CcFlushCache (attempt 2)

TAN-Gaming · Nov 16, 2024 · 915306a · 915306a
1 parent 97c02f5
commit 915306a
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Showing 2 changed files with 64 additions and 31 deletions.
diff --git a/ntoskrnl/cc/view.c b/ntoskrnl/cc/view.c
@@ -1036,33 +1036,62 @@ CcRosInternalFreeVacb (
     return STATUS_SUCCESS;
 }
 
+BOOLEAN
+CcpAcquireFileCacheForFlush(
+    _In_ PROS_SHARED_CACHE_MAP SharedCacheMap,
+    _In_ BOOLEAN Wait)
+{
+    if (Wait)
+    {
+        ExAcquireFastMutex(&SharedCacheMap->FlushCacheLock);
+        return TRUE;
+    }
+
+    return ExTryToAcquireFastMutex(&SharedCacheMap->FlushCacheLock);
+}
+
+VOID
+CcpReleaseFileCacheFromFlush(
+    _In_ PROS_SHARED_CACHE_MAP SharedCacheMap)
+{
+    ExReleaseFastMutex(&SharedCacheMap->FlushCacheLock);
+}
+
 static
 VOID
-CcpUpdateFlushedFileCache(
+CcpFileCacheFlushComplete(
     _In_ PROS_SHARED_CACHE_MAP SharedCacheMap,
     _In_ ULONG FlushedPages,
+    _In_ BOOLEAN UpdateCacheMap,
     _In_ LONGLONG NewVdl)
 {
     KIRQL OldIrql;
 
     OldIrql = KeAcquireQueuedSpinLock(LockQueueMasterLock);
-    KeAcquireSpinLockAtDpcLevel(&SharedCacheMap->CacheMapLock);
 
-    /* Update number of dirty pages and check dirty status */
+    /* Update total dirty pages */
     CcTotalDirtyPages -= FlushedPages;
-    SharedCacheMap->DirtyPages -= FlushedPages;
-    if (SharedCacheMap->DirtyPages == 0)
+
+    if (UpdateCacheMap)
     {
-        /* The file cache is no longer dirty, remove from dirty list */
-        RemoveEntryList(&SharedCacheMap->SharedCacheMapLinks);
-        InsertTailList(&CcCleanSharedCacheMapList, &SharedCacheMap->SharedCacheMapLinks);
-    }
+        KeAcquireSpinLockAtDpcLevel(&SharedCacheMap->CacheMapLock);
+
+        /* Update number of dirty pages and check dirty status */
+        SharedCacheMap->DirtyPages -= FlushedPages;
+        if (SharedCacheMap->DirtyPages == 0)
+        {
+            /* The file cache is no longer dirty, remove from dirty list */
+            RemoveEntryList(&SharedCacheMap->SharedCacheMapLinks);
+            InsertTailList(&CcCleanSharedCacheMapList, &SharedCacheMap->SharedCacheMapLinks);
+        }
 
-    /* Update VDL */
-    if (SharedCacheMap->ValidDataLength.QuadPart < NewVdl)
-        SharedCacheMap->ValidDataLength.QuadPart = NewVdl;
+        /* Update VDL */
+        if (SharedCacheMap->ValidDataLength.QuadPart < NewVdl)
+            SharedCacheMap->ValidDataLength.QuadPart = NewVdl;
+
+        KeReleaseSpinLockFromDpcLevel(&SharedCacheMap->CacheMapLock);
+    }
 
-    KeReleaseSpinLockFromDpcLevel(&SharedCacheMap->CacheMapLock);
     KeReleaseQueuedSpinLock(LockQueueMasterLock, OldIrql);
 }
 
@@ -1145,7 +1174,10 @@ CcpFlushFileCache(
             MmLength = VACB_MAPPING_GRANULARITY - (FlushStart % VACB_MAPPING_GRANULARITY);
         }
 
-        Status = MmFlushSegment(SharedCacheMap->FileObject->SectionObjectPointer, &MmOffset, MmLength, &MmFlushedPages);
+        Status = MmFlushSegment(SharedCacheMap->FileObject->SectionObjectPointer,
+                                &MmOffset,
+                                MmLength,
+                                &MmFlushedPages);
         FlushedPages += MmFlushedPages;
         if (!NT_SUCCESS(Status))
             break;
@@ -1157,21 +1189,7 @@ CcpFlushFileCache(
     if (HaveFileLock)
         FsRtlReleaseFileForCcFlush(SharedCacheMap->FileObject);
 
-    if (UpdateCacheMap)
-    {
-        CcpUpdateFlushedFileCache(SharedCacheMap, FlushedPages, FlushStart);
-    }
-    else if (FlushedPages != 0)
-    {
-        KIRQL OldIrql;
-
-        OldIrql = KeAcquireQueuedSpinLock(LockQueueMasterLock);
-
-        /* Update total dirty pages */
-        CcTotalDirtyPages -= FlushedPages;
-
-        KeReleaseQueuedSpinLock(LockQueueMasterLock, OldIrql);
-    }
+    CcpFileCacheFlushComplete(SharedCacheMap, FlushedPages, UpdateCacheMap, FlushStart);
 
 Quit:
     if (IoStatus)
@@ -1228,8 +1246,13 @@ CcFlushCache(
     SharedCacheMap = SectionObjectPointers->SharedCacheMap;
     if (SharedCacheMap)
     {
-        /* Call internal function */
+        CcpAcquireFileCacheForFlush(SharedCacheMap, TRUE);
+
         CcpFlushFileCache(SharedCacheMap, FileOffset, Length, TRUE, IoStatus);
+
+        CcpReleaseFileCacheFromFlush(SharedCacheMap);
+
+        /* IoStatus was handled by the internal function. We can simply return here */
         return;
     }
     else
@@ -1347,6 +1370,7 @@ CcRosInitializeFileCache (
         KeInitializeSpinLock(&SharedCacheMap->CacheMapLock);
         InitializeListHead(&SharedCacheMap->CacheMapVacbListHead);
         InitializeListHead(&SharedCacheMap->BcbList);
+        ExInitializeFastMutex(&SharedCacheMap->FlushCacheLock);
 
         SharedCacheMap->Flags = SHARED_CACHE_MAP_IN_CREATION;
 

diff --git a/ntoskrnl/include/internal/cc.h b/ntoskrnl/include/internal/cc.h
@@ -194,6 +194,7 @@ typedef struct _ROS_SHARED_CACHE_MAP
     LIST_ENTRY CacheMapVacbListHead;
     BOOLEAN PinAccess;
     KSPIN_LOCK CacheMapLock;
+    FAST_MUTEX FlushCacheLock;
 #if DBG
     BOOLEAN Trace; /* enable extra trace output for this cache map and it's VACBs */
 #endif
@@ -202,7 +203,6 @@ typedef struct _ROS_SHARED_CACHE_MAP
 #define READAHEAD_DISABLED 0x1
 #define WRITEBEHIND_DISABLED 0x2
 #define SHARED_CACHE_MAP_IN_CREATION 0x4
-#define SHARED_CACHE_MAP_IN_LAZYWRITE 0x8
 #define MAX_FLUSH_LENGTH ((MAXULONG >> PAGE_SHIFT) * PAGE_SIZE)
 
 typedef struct _ROS_VACB
@@ -351,6 +351,15 @@ CcpMarkDirtyFileCache(
     _In_ PVOID BaseAddress,
     _In_ ULONG Length);
 
+BOOLEAN
+CcpAcquireFileCacheForFlush(
+    _In_ PROS_SHARED_CACHE_MAP SharedCacheMap,
+    _In_ BOOLEAN Wait);
+
+VOID
+CcpReleaseFileCacheFromFlush(
+    _In_ PROS_SHARED_CACHE_MAP SharedCacheMap);
+
 VOID
 CcpFlushFileCache(
     _In_ PROS_SHARED_CACHE_MAP SharedCacheMap,