[ros-diffs] [cgutman] 54745: [NTOSKRNL] - Reference the cache segment when flushing to avoid a race between deleting the file cache and the balancer flushing pages to disk which causes random cache segments to...

Author: cgutman
Date: Fri Dec 23 23:20:09 2011
New Revision: 54745

URL: http://svn.reactos.org/svn/reactos?rev=54745&view=rev
Log:
[NTOSKRNL]
- Reference the cache segment when flushing to avoid a race between deleting the file cache and the balancer flushing pages to disk which causes random cache segments to be freed while we're holding a lock on it
- Fixes a crash in KeReleaseMutex (used to be a crash in ExReleasePushLock) during periods of high memory load

Modified:
    trunk/reactos/ntoskrnl/cc/view.c

Modified: trunk/reactos/ntoskrnl/cc/view.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/cc/view.c?rev=5474...
==============================================================================
--- trunk/reactos/ntoskrnl/cc/view.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/cc/view.c [iso-8859-1] Fri Dec 23 23:20:09 2011
@@ -204,10 +204,13 @@
                                     DirtySegmentListEntry);
         current_entry = current_entry->Flink;

+        CcRosCacheSegmentIncRefCount(current);
+
         Locked = current->Bcb->Callbacks->AcquireForLazyWrite(
             current->Bcb->LazyWriteContext, Wait);
         if (!Locked)
         {
+            CcRosCacheSegmentDecRefCount(current);
             continue;
         }

@@ -220,6 +223,7 @@
         {
             current->Bcb->Callbacks->ReleaseFromLazyWrite(
                 current->Bcb->LazyWriteContext);
+            CcRosCacheSegmentDecRefCount(current);
             continue;
         }

@@ -229,6 +233,7 @@
             KeReleaseMutex(&current->Mutex, 0);
             current->Bcb->Callbacks->ReleaseFromLazyWrite(
                 current->Bcb->LazyWriteContext);
+            CcRosCacheSegmentDecRefCount(current);
             continue;
         }

@@ -241,6 +246,9 @@
         KeReleaseMutex(&current->Mutex, 0);
         current->Bcb->Callbacks->ReleaseFromLazyWrite(
             current->Bcb->LazyWriteContext);
+        
+        KeAcquireGuardedMutex(&ViewLock);
+        CcRosCacheSegmentDecRefCount(current);

if (!NT_SUCCESS(Status) &&  (Status != STATUS_END_OF_FILE))
         {
@@ -251,8 +259,7 @@
             (*Count) += PagesPerSegment;
             Target -= PagesPerSegment;
         }
-        
-        KeAcquireGuardedMutex(&ViewLock);
+
         current_entry = DirtySegmentListHead.Flink;
     }