[ros-diffs] [tfaber] 60481: [NTOSKRNL] - BCB::CacheSegmentSize has no reason to vary at runtime. Replace it with the constant VACB_MAPPING_GRANULARITY.

Author: tfaber
Date: Mon Sep 30 19:40:09 2013
New Revision: 60481

URL: http://svn.reactos.org/svn/reactos?rev=60481&view=rev
Log:
[NTOSKRNL]
- BCB::CacheSegmentSize has no reason to vary at runtime. Replace it with the constant
VACB_MAPPING_GRANULARITY.

Modified:
    trunk/reactos/ntoskrnl/cc/copy.c
    trunk/reactos/ntoskrnl/cc/fs.c
    trunk/reactos/ntoskrnl/cc/pin.c
    trunk/reactos/ntoskrnl/cc/view.c
    trunk/reactos/ntoskrnl/mm/section.c

Modified: trunk/reactos/ntoskrnl/cc/copy.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/cc/copy.c?rev=604…
==============================================================================
--- trunk/reactos/ntoskrnl/cc/copy.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/cc/copy.c	[iso-8859-1] Mon Sep 30 19:40:09 2013
@@ -87,7 +87,7 @@
          */
         if (current->Valid)
         {
-            TempLength = min(Bcb->CacheSegmentSize, Length);
+            TempLength = min(VACB_MAPPING_GRANULARITY, Length);
             memcpy(Buffer, current->BaseAddress, TempLength);
 
             Buffer = (PVOID)((ULONG_PTR)Buffer + TempLength);
@@ -116,7 +116,7 @@
             while ((current2 != NULL) && !current2->Valid &&
(current_size < MAX_RW_LENGTH))
             {
                 current2 = current2->NextInChain;
-                current_size += Bcb->CacheSegmentSize;
+                current_size += VACB_MAPPING_GRANULARITY;
             }
 
             /*
@@ -130,12 +130,12 @@
             while ((current2 != NULL) && !current2->Valid &&
(current_size < MAX_RW_LENGTH))
             {
                 PVOID address = current2->BaseAddress;
-                for (i = 0; i < (Bcb->CacheSegmentSize / PAGE_SIZE); i++, address =
RVA(address, PAGE_SIZE))
+                for (i = 0; i < (VACB_MAPPING_GRANULARITY / PAGE_SIZE); i++, address =
RVA(address, PAGE_SIZE))
                 {
                     *MdlPages++ = MmGetPfnForProcess(NULL, address);
                 }
                 current2 = current2->NextInChain;
-                current_size += Bcb->CacheSegmentSize;
+                current_size += VACB_MAPPING_GRANULARITY;
             }
 
             /*
@@ -172,14 +172,14 @@
             {
                 previous = current;
                 current = current->NextInChain;
-                TempLength = min(Bcb->CacheSegmentSize, Length);
+                TempLength = min(VACB_MAPPING_GRANULARITY, Length);
                 memcpy(Buffer, previous->BaseAddress, TempLength);
 
                 Buffer = (PVOID)((ULONG_PTR)Buffer + TempLength);
 
                 Length = Length - TempLength;
                 CcRosReleaseCacheSegment(Bcb, previous, TRUE, FALSE, FALSE);
-                current_size += Bcb->CacheSegmentSize;
+                current_size += VACB_MAPPING_GRANULARITY;
             }
         }
     }
@@ -200,9 +200,9 @@
 
     SegOffset.QuadPart = CacheSeg->FileOffset;
     Size = (ULONG)(CacheSeg->Bcb->AllocationSize.QuadPart -
CacheSeg->FileOffset);
-    if (Size > CacheSeg->Bcb->CacheSegmentSize)
-    {
-        Size = CacheSeg->Bcb->CacheSegmentSize;
+    if (Size > VACB_MAPPING_GRANULARITY)
+    {
+        Size = VACB_MAPPING_GRANULARITY;
     }
 
     Mdl = IoAllocateMdl(CacheSeg->BaseAddress, Size, FALSE, FALSE, NULL);
@@ -229,10 +229,10 @@
         return Status;
     }
 
-    if (CacheSeg->Bcb->CacheSegmentSize > Size)
+    if (VACB_MAPPING_GRANULARITY > Size)
     {
         RtlZeroMemory((char*)CacheSeg->BaseAddress + Size,
-                      CacheSeg->Bcb->CacheSegmentSize - Size);
+                      VACB_MAPPING_GRANULARITY - Size);
     }
 
     return STATUS_SUCCESS;
@@ -253,9 +253,9 @@
     CacheSeg->Dirty = FALSE;
     SegOffset.QuadPart = CacheSeg->FileOffset;
     Size = (ULONG)(CacheSeg->Bcb->AllocationSize.QuadPart -
CacheSeg->FileOffset);
-    if (Size > CacheSeg->Bcb->CacheSegmentSize)
-    {
-        Size = CacheSeg->Bcb->CacheSegmentSize;
+    if (Size > VACB_MAPPING_GRANULARITY)
+    {
+        Size = VACB_MAPPING_GRANULARITY;
     }
     //
     // Nonpaged pool PDEs in ReactOS must actually be synchronized between the
@@ -363,7 +363,7 @@
             current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                         BcbSegmentListEntry);
             if (!current->Valid &&
-                DoSegmentsIntersect(current->FileOffset, Bcb->CacheSegmentSize,
+                DoSegmentsIntersect(current->FileOffset, VACB_MAPPING_GRANULARITY,
                                     ReadOffset, Length))
             {
                 KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
@@ -378,13 +378,13 @@
         KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
     }
 
-    TempLength = ReadOffset % Bcb->CacheSegmentSize;
+    TempLength = ReadOffset % VACB_MAPPING_GRANULARITY;
     if (TempLength != 0)
     {
-        TempLength = min (Length, Bcb->CacheSegmentSize - TempLength);
+        TempLength = min (Length, VACB_MAPPING_GRANULARITY - TempLength);
         Status = CcRosRequestCacheSegment(Bcb,
                                           ROUND_DOWN(ReadOffset,
-                                                  Bcb->CacheSegmentSize),
+                                                  VACB_MAPPING_GRANULARITY),
                                           &BaseAddress, &Valid, &CacheSeg);
         if (!NT_SUCCESS(Status))
         {
@@ -404,7 +404,7 @@
                 return FALSE;
             }
         }
-        memcpy (Buffer, (char*)BaseAddress + ReadOffset % Bcb->CacheSegmentSize,
+        memcpy (Buffer, (char*)BaseAddress + ReadOffset % VACB_MAPPING_GRANULARITY,
                 TempLength);
         CcRosReleaseCacheSegment(Bcb, CacheSeg, TRUE, FALSE, FALSE);
         ReadLength += TempLength;
@@ -415,7 +415,7 @@
 
     while (Length > 0)
     {
-        TempLength = min(max(Bcb->CacheSegmentSize, MAX_RW_LENGTH), Length);
+        TempLength = min(max(VACB_MAPPING_GRANULARITY, MAX_RW_LENGTH), Length);
         Status = ReadCacheSegmentChain(Bcb, ReadOffset, TempLength, Buffer);
         if (!NT_SUCCESS(Status))
         {
@@ -479,7 +479,7 @@
             CacheSeg = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                          BcbSegmentListEntry);
             if (!CacheSeg->Valid &&
-                DoSegmentsIntersect(CacheSeg->FileOffset, Bcb->CacheSegmentSize,
+                DoSegmentsIntersect(CacheSeg->FileOffset, VACB_MAPPING_GRANULARITY,
                                     WriteOffset, Length))
             {
                 KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
@@ -493,12 +493,12 @@
         KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
     }
 
-    TempLength = WriteOffset % Bcb->CacheSegmentSize;
+    TempLength = WriteOffset % VACB_MAPPING_GRANULARITY;
     if (TempLength != 0)
     {
         ULONG ROffset;
-        ROffset = ROUND_DOWN(WriteOffset, Bcb->CacheSegmentSize);
-        TempLength = min (Length, Bcb->CacheSegmentSize - TempLength);
+        ROffset = ROUND_DOWN(WriteOffset, VACB_MAPPING_GRANULARITY);
+        TempLength = min (Length, VACB_MAPPING_GRANULARITY - TempLength);
         Status = CcRosRequestCacheSegment(Bcb, ROffset,
                                           &BaseAddress, &Valid, &CacheSeg);
         if (!NT_SUCCESS(Status))
@@ -512,7 +512,7 @@
                 return FALSE;
             }
         }
-        memcpy ((char*)BaseAddress + WriteOffset % Bcb->CacheSegmentSize,
+        memcpy ((char*)BaseAddress + WriteOffset % VACB_MAPPING_GRANULARITY,
                 Buffer, TempLength);
         CcRosReleaseCacheSegment(Bcb, CacheSeg, TRUE, TRUE, FALSE);
 
@@ -524,7 +524,7 @@
 
     while (Length > 0)
     {
-        TempLength = min (Bcb->CacheSegmentSize, Length);
+        TempLength = min (VACB_MAPPING_GRANULARITY, Length);
         Status = CcRosRequestCacheSegment(Bcb,
                                           WriteOffset,
                                           &BaseAddress,
@@ -534,7 +534,7 @@
         {
             return FALSE;
         }
-        if (!Valid && TempLength < Bcb->CacheSegmentSize)
+        if (!Valid && TempLength < VACB_MAPPING_GRANULARITY)
         {
             if (!NT_SUCCESS(ReadCacheSegment(CacheSeg)))
             {
@@ -699,7 +699,7 @@
                 CacheSeg = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                              BcbSegmentListEntry);
                 if (!CacheSeg->Valid &&
-                    DoSegmentsIntersect(CacheSeg->FileOffset,
Bcb->CacheSegmentSize,
+                    DoSegmentsIntersect(CacheSeg->FileOffset,
VACB_MAPPING_GRANULARITY,
                                         WriteOffset.u.LowPart, Length))
                 {
                     KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
@@ -716,7 +716,7 @@
         while (Length > 0)
         {
             ULONG Offset;
-            Offset = WriteOffset.u.LowPart % Bcb->CacheSegmentSize;
+            Offset = WriteOffset.u.LowPart % VACB_MAPPING_GRANULARITY;
             if (Length + Offset > MAX_ZERO_LENGTH)
             {
                 CurrentLength = MAX_ZERO_LENGTH - Offset;
@@ -735,9 +735,9 @@
 
             while (current != NULL)
             {
-                Offset = WriteOffset.u.LowPart % Bcb->CacheSegmentSize;
+                Offset = WriteOffset.u.LowPart % VACB_MAPPING_GRANULARITY;
                 if ((Offset != 0) ||
-                    (Offset + CurrentLength < Bcb->CacheSegmentSize))
+                    (Offset + CurrentLength < VACB_MAPPING_GRANULARITY))
                 {
                     if (!current->Valid)
                     {
@@ -749,11 +749,11 @@
                                     Status);
                         }
                     }
-                    TempLength = min (CurrentLength, Bcb->CacheSegmentSize - Offset);
+                    TempLength = min (CurrentLength, VACB_MAPPING_GRANULARITY - Offset);
                 }
                 else
                 {
-                    TempLength = Bcb->CacheSegmentSize;
+                    TempLength = VACB_MAPPING_GRANULARITY;
                 }
                 memset ((PUCHAR)current->BaseAddress + Offset, 0, TempLength);
 

Modified: trunk/reactos/ntoskrnl/cc/fs.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/cc/fs.c?rev=60481…
==============================================================================
--- trunk/reactos/ntoskrnl/cc/fs.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/cc/fs.c	[iso-8859-1] Mon Sep 30 19:40:09 2013
@@ -173,7 +173,7 @@
                     if (current->Dirty)
                     {
                         RemoveEntryList(&current->DirtySegmentListEntry);
-                        DirtyPageCount -= Bcb->CacheSegmentSize / PAGE_SIZE;
+                        DirtyPageCount -= VACB_MAPPING_GRANULARITY / PAGE_SIZE;
                     }
                     InsertHeadList(&FreeListHead,
&current->BcbSegmentListEntry);
                 }

Modified: trunk/reactos/ntoskrnl/cc/pin.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/cc/pin.c?rev=6048…
==============================================================================
--- trunk/reactos/ntoskrnl/cc/pin.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/cc/pin.c	[iso-8859-1] Mon Sep 30 19:40:09 2013
@@ -57,12 +57,12 @@
            Bcb->AllocationSize.QuadPart,
            Bcb->FileSize.QuadPart);
 
-    if (ReadOffset % Bcb->CacheSegmentSize + Length > Bcb->CacheSegmentSize)
+    if (ReadOffset % VACB_MAPPING_GRANULARITY + Length > VACB_MAPPING_GRANULARITY)
     {
         return FALSE;
     }
 
-    ROffset = ROUND_DOWN(ReadOffset, Bcb->CacheSegmentSize);
+    ROffset = ROUND_DOWN(ReadOffset, VACB_MAPPING_GRANULARITY);
     Status = CcRosRequestCacheSegment(Bcb,
                                       ROffset,
                                       pBuffer,
@@ -88,7 +88,7 @@
         }
     }
 
-    *pBuffer = (PVOID)((ULONG_PTR)(*pBuffer) + (ReadOffset % Bcb->CacheSegmentSize));
+    *pBuffer = (PVOID)((ULONG_PTR)(*pBuffer) + (ReadOffset % VACB_MAPPING_GRANULARITY));
     iBcb = ExAllocateFromNPagedLookasideList(&iBcbLookasideList);
     if (iBcb == NULL)
     {

Modified: trunk/reactos/ntoskrnl/cc/view.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/cc/view.c?rev=604…
==============================================================================
--- trunk/reactos/ntoskrnl/cc/view.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/cc/view.c	[iso-8859-1] Mon Sep 30 19:40:09 2013
@@ -164,7 +164,7 @@
 
         CacheSegment->Dirty = FALSE;
         RemoveEntryList(&CacheSegment->DirtySegmentListEntry);
-        DirtyPageCount -= CacheSegment->Bcb->CacheSegmentSize / PAGE_SIZE;
+        DirtyPageCount -= VACB_MAPPING_GRANULARITY / PAGE_SIZE;
         CcRosCacheSegmentDecRefCount(CacheSegment);
 
         KeReleaseSpinLock(&CacheSegment->Bcb->BcbLock, oldIrql);
@@ -243,7 +243,7 @@
             continue;
         }
 
-        PagesPerSegment = current->Bcb->CacheSegmentSize / PAGE_SIZE;
+        PagesPerSegment = VACB_MAPPING_GRANULARITY / PAGE_SIZE;
 
         KeReleaseGuardedMutex(&ViewLock);
 
@@ -329,7 +329,7 @@
             KeReleaseGuardedMutex(&ViewLock);
 
             /* Page out the segment */
-            for (i = 0; i < current->Bcb->CacheSegmentSize / PAGE_SIZE; i++)
+            for (i = 0; i < VACB_MAPPING_GRANULARITY / PAGE_SIZE; i++)
             {
                 Page = (PFN_NUMBER)(MmGetPhysicalAddress((PUCHAR)current->BaseAddress
+ (i * PAGE_SIZE)).QuadPart >> PAGE_SHIFT);
 
@@ -356,7 +356,7 @@
             InsertHeadList(&FreeList, &current->BcbSegmentListEntry);
 
             /* Calculate how many pages we freed for Mm */
-            PagesPerSegment = current->Bcb->CacheSegmentSize / PAGE_SIZE;
+            PagesPerSegment = VACB_MAPPING_GRANULARITY / PAGE_SIZE;
             PagesFreed = min(PagesPerSegment, Target);
             Target -= PagesFreed;
             (*NrFreed) += PagesFreed;
@@ -427,7 +427,7 @@
     if (!WasDirty && CacheSeg->Dirty)
     {
         InsertTailList(&DirtySegmentListHead,
&CacheSeg->DirtySegmentListEntry);
-        DirtyPageCount += Bcb->CacheSegmentSize / PAGE_SIZE;
+        DirtyPageCount += VACB_MAPPING_GRANULARITY / PAGE_SIZE;
     }
 
     if (Mapped)
@@ -474,7 +474,7 @@
     {
         current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                     BcbSegmentListEntry);
-        if (IsPointInSegment(current->FileOffset, Bcb->CacheSegmentSize,
+        if (IsPointInSegment(current->FileOffset, VACB_MAPPING_GRANULARITY,
                              FileOffset))
         {
             CcRosCacheSegmentIncRefCount(current);
@@ -523,7 +523,7 @@
     if (!CacheSeg->Dirty)
     {
         InsertTailList(&DirtySegmentListHead,
&CacheSeg->DirtySegmentListEntry);
-        DirtyPageCount += Bcb->CacheSegmentSize / PAGE_SIZE;
+        DirtyPageCount += VACB_MAPPING_GRANULARITY / PAGE_SIZE;
     }
     else
     {
@@ -576,7 +576,7 @@
     if (!WasDirty && NowDirty)
     {
         InsertTailList(&DirtySegmentListHead,
&CacheSeg->DirtySegmentListEntry);
-        DirtyPageCount += Bcb->CacheSegmentSize / PAGE_SIZE;
+        DirtyPageCount += VACB_MAPPING_GRANULARITY / PAGE_SIZE;
     }
 
     CcRosCacheSegmentDecRefCount(CacheSeg);
@@ -628,7 +628,7 @@
     current->Valid = FALSE;
     current->Dirty = FALSE;
     current->PageOut = FALSE;
-    current->FileOffset = ROUND_DOWN(FileOffset, Bcb->CacheSegmentSize);
+    current->FileOffset = ROUND_DOWN(FileOffset, VACB_MAPPING_GRANULARITY);
     current->Bcb = Bcb;
 #if DBG
     if ( Bcb->Trace )
@@ -661,7 +661,7 @@
     {
         current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                     BcbSegmentListEntry);
-        if (IsPointInSegment(current->FileOffset, Bcb->CacheSegmentSize,
+        if (IsPointInSegment(current->FileOffset, VACB_MAPPING_GRANULARITY,
                              FileOffset))
         {
             CcRosCacheSegmentIncRefCount(current);
@@ -713,7 +713,7 @@
 #ifdef CACHE_BITMAP
     KeAcquireSpinLock(&CiCacheSegMappingRegionLock, &oldIrql);
 
-    StartingOffset = RtlFindClearBitsAndSet(&CiCacheSegMappingRegionAllocMap,
Bcb->CacheSegmentSize / PAGE_SIZE, CiCacheSegMappingRegionHint);
+    StartingOffset = RtlFindClearBitsAndSet(&CiCacheSegMappingRegionAllocMap,
VACB_MAPPING_GRANULARITY / PAGE_SIZE, CiCacheSegMappingRegionHint);
 
     if (StartingOffset == 0xffffffff)
     {
@@ -725,7 +725,7 @@
 
     if (CiCacheSegMappingRegionHint == StartingOffset)
     {
-        CiCacheSegMappingRegionHint += Bcb->CacheSegmentSize / PAGE_SIZE;
+        CiCacheSegMappingRegionHint += VACB_MAPPING_GRANULARITY / PAGE_SIZE;
     }
 
     KeReleaseSpinLock(&CiCacheSegMappingRegionLock, oldIrql);
@@ -735,7 +735,7 @@
     Status = MmCreateMemoryArea(MmGetKernelAddressSpace(),
                                 0, // nothing checks for cache_segment mareas, so set to
0
                                 &current->BaseAddress,
-                                Bcb->CacheSegmentSize,
+                                VACB_MAPPING_GRANULARITY,
                                 PAGE_READWRITE,
                                 (PMEMORY_AREA*)&current->MemoryArea,
                                 FALSE,
@@ -761,7 +761,7 @@
     }
 #endif
 
-    MmMapMemoryArea(current->BaseAddress, Bcb->CacheSegmentSize,
+    MmMapMemoryArea(current->BaseAddress, VACB_MAPPING_GRANULARITY,
                     MC_CACHE, PAGE_READWRITE);
 
     return(STATUS_SUCCESS);
@@ -784,17 +784,17 @@
 
     DPRINT("CcRosGetCacheSegmentChain()\n");
 
-    Length = ROUND_UP(Length, Bcb->CacheSegmentSize);
+    Length = ROUND_UP(Length, VACB_MAPPING_GRANULARITY);
 
     CacheSegList = _alloca(sizeof(PCACHE_SEGMENT) *
-                           (Length / Bcb->CacheSegmentSize));
+                           (Length / VACB_MAPPING_GRANULARITY));
 
     /*
      * Look for a cache segment already mapping the same data.
      */
-    for (i = 0; i < (Length / Bcb->CacheSegmentSize); i++)
-    {
-        ULONG CurrentOffset = FileOffset + (i * Bcb->CacheSegmentSize);
+    for (i = 0; i < (Length / VACB_MAPPING_GRANULARITY); i++)
+    {
+        ULONG CurrentOffset = FileOffset + (i * VACB_MAPPING_GRANULARITY);
         current = CcRosLookupCacheSegment(Bcb, CurrentOffset);
         if (current != NULL)
         {
@@ -815,7 +815,7 @@
         }
     }
 
-    for (i = 0; i < (Length / Bcb->CacheSegmentSize); i++)
+    for (i = 0; i < (Length / VACB_MAPPING_GRANULARITY); i++)
     {
         if (i == 0)
         {
@@ -902,10 +902,10 @@
 
     ASSERT(Bcb);
 
-    if ((FileOffset % Bcb->CacheSegmentSize) != 0)
+    if ((FileOffset % VACB_MAPPING_GRANULARITY) != 0)
     {
         DPRINT1("Bad fileoffset %x should be multiple of %x",
-                FileOffset, Bcb->CacheSegmentSize);
+                FileOffset, VACB_MAPPING_GRANULARITY);
         KeBugCheck(CACHE_MANAGER);
     }
 
@@ -958,7 +958,7 @@
     }
 #endif
 #ifdef CACHE_BITMAP
-    RegionSize = CacheSeg->Bcb->CacheSegmentSize / PAGE_SIZE;
+    RegionSize = VACB_MAPPING_GRANULARITY / PAGE_SIZE;
 
     /* Unmap all the pages. */
     for (i = 0; i < RegionSize; i++)
@@ -1054,10 +1054,10 @@
                 KeReleaseGuardedMutex(&ViewLock);
             }
 
-            Offset.QuadPart += Bcb->CacheSegmentSize;
-            if (Length > Bcb->CacheSegmentSize)
+            Offset.QuadPart += VACB_MAPPING_GRANULARITY;
+            if (Length > VACB_MAPPING_GRANULARITY)
             {
-                Length -= Bcb->CacheSegmentSize;
+                Length -= VACB_MAPPING_GRANULARITY;
             }
             else
             {
@@ -1121,7 +1121,7 @@
             if (current->Dirty)
             {
                 RemoveEntryList(&current->DirtySegmentListEntry);
-                DirtyPageCount -= Bcb->CacheSegmentSize / PAGE_SIZE;
+                DirtyPageCount -= VACB_MAPPING_GRANULARITY / PAGE_SIZE;
                 DPRINT1("Freeing dirty segment\n");
             }
             InsertHeadList(&FreeList, &current->BcbSegmentListEntry);

Modified: trunk/reactos/ntoskrnl/mm/section.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/section.c?rev=…
==============================================================================
--- trunk/reactos/ntoskrnl/mm/section.c	[iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/section.c	[iso-8859-1] Mon Sep 30 19:40:09 2013
@@ -1177,7 +1177,7 @@
 
       Process = PsGetCurrentProcess();
       PageAddr = MiMapPageInHyperSpace(Process, *Page, &Irql);
-      CacheSegOffset = (ULONG_PTR)(BaseOffset + CacheSeg->Bcb->CacheSegmentSize -
FileOffset);
+      CacheSegOffset = (ULONG_PTR)(BaseOffset + VACB_MAPPING_GRANULARITY - FileOffset);
       Length = RawLength - SegOffset;
       if (Length <= CacheSegOffset && Length <= PAGE_SIZE)
       {