[NTOS:CC] Fix usage of FsRtlAcquireFileForCcFlushEx

CcRosFlushVacb: Also add a comment about the reason for calling CcRosUnmarkDirtyVacb before flush.
TAN-Gaming · Nov 22, 2024 · cb56cff · cb56cff
1 parent e3c859e
commit cb56cff
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Showing 2 changed files with 16 additions and 21 deletions.
diff --git a/ntoskrnl/cc/view.c b/ntoskrnl/cc/view.c
@@ -164,33 +164,20 @@ CcRosFlushVacb (
     _Out_opt_ PIO_STATUS_BLOCK Iosb)
 {
     NTSTATUS Status;
-    BOOLEAN HaveLock = FALSE;
     PROS_SHARED_CACHE_MAP SharedCacheMap = Vacb->SharedCacheMap;
 
+    /* Unmark dirty first, and then write. This will avoid trying to flush
+     * twice a dirty VACB under high IOs pressure. */
     CcRosUnmarkDirtyVacb(Vacb, TRUE);
 
-    /* Lock for flush, if we are not already the top-level */
-    if (IoGetTopLevelIrp() != (PIRP)FSRTL_CACHE_TOP_LEVEL_IRP)
-    {
-        Status = FsRtlAcquireFileForCcFlushEx(Vacb->SharedCacheMap->FileObject);
-        if (!NT_SUCCESS(Status))
-            goto quit;
-        HaveLock = TRUE;
-    }
-
     Status = MmFlushSegment(SharedCacheMap->FileObject->SectionObjectPointer,
                             &Vacb->FileOffset,
                             VACB_MAPPING_GRANULARITY,
                             Iosb);
-
-    if (HaveLock)
-    {
-        FsRtlReleaseFileForCcFlush(Vacb->SharedCacheMap->FileObject);
-    }
-
-quit:
     if (!NT_SUCCESS(Status))
+    {
         CcRosMarkDirtyVacb(Vacb);
+    }
     else
     {
         /* Update VDL */
@@ -1108,6 +1095,7 @@ CcFlushCache (
     PROS_SHARED_CACHE_MAP SharedCacheMap;
     LONGLONG FlushStart, FlushEnd;
     NTSTATUS Status;
+    BOOLEAN HaveFileLock = FALSE;
 
     CCTRACE(CC_API_DEBUG, "SectionObjectPointers=%p FileOffset=0x%I64X Length=%lu\n",
         SectionObjectPointers, FileOffset ? FileOffset->QuadPart : 0LL, Length);
@@ -1146,7 +1134,15 @@ CcFlushCache (
         IoStatus->Information = 0;
     }
 
-    KeAcquireGuardedMutex(&SharedCacheMap->FlushCacheLock);
+    /* Lock for flush, if we are not already the top-level */
+    if (IoGetTopLevelIrp() != (PIRP)FSRTL_CACHE_TOP_LEVEL_IRP)
+    {
+        Status = FsRtlAcquireFileForCcFlushEx(SharedCacheMap->FileObject);
+        if (!NT_SUCCESS(Status))
+            goto quit;
+
+        HaveFileLock = TRUE;
+    }
 
     /*
      * We flush the VACBs that we find here.
@@ -1217,7 +1213,8 @@ CcFlushCache (
         FlushStart -= FlushStart % VACB_MAPPING_GRANULARITY;
     }
 
-    KeReleaseGuardedMutex(&SharedCacheMap->FlushCacheLock);
+    if (HaveFileLock)
+        FsRtlReleaseFileForCcFlush(SharedCacheMap->FileObject);
 
 quit:
     if (IoStatus)
@@ -1327,7 +1324,6 @@ CcRosInitializeFileCache (
         KeInitializeSpinLock(&SharedCacheMap->CacheMapLock);
         InitializeListHead(&SharedCacheMap->CacheMapVacbListHead);
         InitializeListHead(&SharedCacheMap->BcbList);
-        KeInitializeGuardedMutex(&SharedCacheMap->FlushCacheLock);
 
         SharedCacheMap->Flags = SHARED_CACHE_MAP_IN_CREATION;
 

diff --git a/ntoskrnl/include/internal/cc.h b/ntoskrnl/include/internal/cc.h
@@ -193,7 +193,6 @@ typedef struct _ROS_SHARED_CACHE_MAP
     LIST_ENTRY CacheMapVacbListHead;
     BOOLEAN PinAccess;
     KSPIN_LOCK CacheMapLock;
-    KGUARDED_MUTEX FlushCacheLock;
 #if DBG
     BOOLEAN Trace; /* enable extra trace output for this cache map and it's VACBs */
 #endif