[NTOSKRNL] Simplify (and speedup!) CcCanIWrite() using the dirty pages count in cache...

[reactos.git] / ntoskrnl / cc / copy.c

diff --git a/ntoskrnl/cc/copy.c b/ntoskrnl/cc/copy.c
index dadae02..e194074 100644 (file)
--- a/ntoskrnl/cc/copy.c
+++ b/ntoskrnl/cc/copy.c
@@ -4,7 +4,8 @@
  * FILE:            ntoskrnl/cc/copy.c
  * PURPOSE:         Implements cache managers copy interface
  *
- * PROGRAMMERS:
+ * PROGRAMMERS:     Some people?
+ *                  Pierre Schweitzer (pierre@reactos.org)
  */
 
 /* INCLUDES ******************************************************************/
@@ -375,9 +376,50 @@ CcCanIWrite (
     IN BOOLEAN Wait,
     IN BOOLEAN Retrying)
 {
+    PFSRTL_COMMON_FCB_HEADER Fcb;
+    PROS_SHARED_CACHE_MAP SharedCacheMap;
+
     CCTRACE(CC_API_DEBUG, "FileObject=%p BytesToWrite=%lu Wait=%d Retrying=%d\n",
         FileObject, BytesToWrite, Wait, Retrying);
 
+    /* We cannot write if dirty pages count is above threshold */
+    if (CcTotalDirtyPages > CcDirtyPageThreshold)
+    {
+        return FALSE;
+    }
+
+    /* We cannot write if dirty pages count will bring use above
+     * XXX: Might not be accurate
+     */
+    if (CcTotalDirtyPages + (BytesToWrite / PAGE_SIZE) > CcDirtyPageThreshold)
+    {
+        return FALSE;
+    }
+
+    /* Is there a limit per file object? */
+    Fcb = FileObject->FsContext;
+    SharedCacheMap = FileObject->SectionObjectPointer->SharedCacheMap;
+    if (!BooleanFlagOn(Fcb->Flags, FSRTL_FLAG_LIMIT_MODIFIED_PAGES) ||
+        SharedCacheMap->DirtyPageThreshold == 0)
+    {
+        /* Nope, so that's fine, allow write operation */
+        return TRUE;
+    }
+
+    /* Is dirty page count above local threshold? */
+    if (SharedCacheMap->DirtyPages > SharedCacheMap->DirtyPageThreshold)
+    {
+        return FALSE;
+    }
+
+    /* We cannot write if dirty pages count will bring use above
+     * XXX: Might not be accurate
+     */
+    if (SharedCacheMap->DirtyPages + (BytesToWrite / PAGE_SIZE) > SharedCacheMap->DirtyPageThreshold)
+    {
+        return FALSE;
+    }
+
     return TRUE;
 }
 
@@ -442,7 +484,7 @@ CcCopyWrite (
 }
 
 /*
- * @unimplemented
+ * @implemented
  */
 VOID
 NTAPI
@@ -454,10 +496,43 @@ CcDeferWrite (
     IN ULONG BytesToWrite,
     IN BOOLEAN Retrying)
 {
+    PROS_DEFERRED_WRITE_CONTEXT Context;
+
     CCTRACE(CC_API_DEBUG, "FileObject=%p PostRoutine=%p Context1=%p Context2=%p BytesToWrite=%lu Retrying=%d\n",
         FileObject, PostRoutine, Context1, Context2, BytesToWrite, Retrying);
 
-    PostRoutine(Context1, Context2);
+    /* Try to allocate a context for queueing the write operation */
+    Context = ExAllocatePoolWithTag(NonPagedPool, sizeof(ROS_DEFERRED_WRITE_CONTEXT), 'CcDw');
+    /* If it failed, immediately execute the operation! */
+    if (Context == NULL)
+    {
+        PostRoutine(Context1, Context2);
+        return;
+    }
+
+    /* Otherwise, initialize the context */
+    Context->FileObject = FileObject;
+    Context->PostRoutine = PostRoutine;
+    Context->Context1 = Context1;
+    Context->Context2 = Context2;
+    Context->BytesToWrite = BytesToWrite;
+    Context->Retrying = Retrying;
+
+    /* And queue it */
+    if (Retrying)
+    {
+        /* To the top, if that's a retry */
+        ExInterlockedInsertHeadList(&CcDeferredWrites,
+                                    &Context->CcDeferredWritesEntry,
+                                    &CcDeferredWriteSpinLock);
+    }
+    else
+    {
+        /* To the bottom, if that's a first time */
+        ExInterlockedInsertTailList(&CcDeferredWrites,
+                                    &Context->CcDeferredWritesEntry,
+                                    &CcDeferredWriteSpinLock);
+    }
 }
 
 /*