reactos/ntoskrnl/cc/view.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            ntoskrnl/cc/view.c
   5  * PURPOSE:         Cache manager
   6  * PROGRAMMER:      David Welch (welch@mcmail.com)
   7  * UPDATE HISTORY:
   8  *                  Created 22/05/98
   9  */
  10
  11 /* INCLUDES *****************************************************************/
  12
  13 #include <ddk/ntddk.h>
  14 #include <ddk/ntifs.h>
  15 #include <internal/mm.h>
  16
  17 //#define NDEBUG
  18 #include <internal/debug.h>
  19
  20 /* TYPES *********************************************************************/
  21
  22 #define CACHE_SEGMENT_SIZE (0x1000)
  23
  24 typedef struct _CACHE_SEGMENT
  25 {
  26    PVOID BaseAddress;
  27    PMEMORY_AREA MemoryArea;
  28    BOOLEAN Valid;
  29    LIST_ENTRY ListEntry;
  30    ULONG FileOffset;
  31    KEVENT Lock;
  32    ULONG ReferenceCount;
  33 } CACHE_SEGMENT, *PCACHE_SEGMENT;
  34
  35 /* FUNCTIONS *****************************************************************/
  36
  37 NTSTATUS CcRequestCachePage(PBCB Bcb,
  38                             ULONG FileOffset,
  39                             PVOID* BaseAddress,
  40                             PBOOLEAN UptoDate)
  41 {
  42    KIRQL oldirql;
  43    PLIST_ENTRY current_entry;
  44    PCACHE_SEGMENT current;
  45
  46    DPRINT("CcRequestCachePage(Bcb %x, FileOffset %x)\n");
  47
  48    KeAcquireSpinLock(&Bcb->BcbLock, &oldirql);
  49
  50    current_entry = Bcb->CacheSegmentListHead.Flink;
  51    while (current_entry != &Bcb->CacheSegmentListHead)
  52      {
  53         current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT, ListEntry);
  54         if (current->FileOffset == PAGE_ROUND_DOWN(FileOffset))
  55           {
  56              current->ReferenceCount++;
  57              KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
  58              KeWaitForSingleObject(&current->Lock,
  59                                    Executive,
  60                                    KernelMode,
  61                                    FALSE,
  62                                    NULL);
  63              *UptoDate = current->Valid;
  64              BaseAddress = current->BaseAddress;
  65              return(STATUS_SUCCESS);
  66           }
  67         current_entry = current_entry->Flink;
  68      }
  69
  70    current = ExAllocatePool(NonPagedPool, sizeof(CACHE_SEGMENT));
  71    current->BaseAddress = NULL;
  72    MmCreateMemoryArea(KernelMode,
  73                       PsGetCurrentProcess(),
  74                       MEMORY_AREA_CACHE_SEGMENT,
  75                       &current->BaseAddress,
  76                       CACHE_SEGMENT_SIZE,
  77                       PAGE_READWRITE,
  78                       &current->MemoryArea);
  79    current->Valid = FALSE;
  80    current->FileOffset = PAGE_ROUND_DOWN(FileOffset);
  81    KeInitializeEvent(&current->Lock, SynchronizationEvent, TRUE);
  82    current->ReferenceCount = 1;
  83    InsertTailList(&Bcb->CacheSegmentListHead, &current->ListEntry);
  84    *UptoDate = current->Valid;
  85    *BaseAddress = current->BaseAddress;
  86    MmSetPage(PsGetCurrentProcess(),
  87              current->BaseAddress,
  88              (ULONG)MmAllocPage(),
  89              PAGE_READWRITE);
  90
  91    KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
  92
  93    return(STATUS_SUCCESS);
  94 }
  95
  96 NTSTATUS CcInitializeFileCache(PFILE_OBJECT FileObject,
  97                                PBCB* Bcb)
  98 {
  99    DPRINT("CcInitializeFileCache(FileObject %x)\n",FileObject);
 100
 101    (*Bcb) = ExAllocatePool(NonPagedPool, sizeof(BCB));
 102    if ((*Bcb) == NULL)
 103      {
 104         return(STATUS_UNSUCCESSFUL);
 105      }
 106
 107    (*Bcb)->FileObject = FileObject;
 108    InitializeListHead(&(*Bcb)->CacheSegmentListHead);
 109    KeInitializeSpinLock(&(*Bcb)->BcbLock);
 110
 111    DPRINT("Finished CcInitializeFileCache() = %x\n", *Bcb);
 112
 113    return(STATUS_SUCCESS);
 114 }
 115
 116
 117