Forgot to add this one in the previous commit: The PageCacheLocker does have

its own source file now that the page daemon source file is gone.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35394 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/vm/PageCacheLocker.cpp

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "PageCacheLocker.h"
+
+#include <vm/VMCache.h>
+
+
+bool
+PageCacheLocker::_IgnorePage(vm_page* page)
+{
+	if (page->busy || page->state == PAGE_STATE_WIRED
+		|| page->state == PAGE_STATE_FREE || page->state == PAGE_STATE_CLEAR
+		|| page->state == PAGE_STATE_UNUSED || page->wired_count > 0)
+		return true;
+
+	return false;
+}
+
+
+bool
+PageCacheLocker::Lock(vm_page* page, bool dontWait)
+{
+	if (_IgnorePage(page))
+		return false;
+
+	// Grab a reference to this cache.
+	VMCache* cache = vm_cache_acquire_locked_page_cache(page, dontWait);
+	if (cache == NULL)
+		return false;
+
+	if (_IgnorePage(page)) {
+		cache->ReleaseRefAndUnlock();
+		return false;
+	}
+
+	fPage = page;
+	return true;
+}
+
+
+void
+PageCacheLocker::Unlock()
+{
+	if (fPage == NULL)
+		return;
+
+	fPage->Cache()->ReleaseRefAndUnlock();
+
+	fPage = NULL;
+}