src/system/kernel/vm/PageCacheLocker.cpp

   1 /*
   2  * Copyright 2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6
   7 #include "PageCacheLocker.h"
   8
   9 #include <vm/VMCache.h>
  10
  11
  12 bool
  13 PageCacheLocker::_IgnorePage(vm_page* page)
  14 {
  15         if (page->busy || page->State() == PAGE_STATE_WIRED
  16                 || page->State() == PAGE_STATE_FREE || page->State() == PAGE_STATE_CLEAR
  17                 || page->State() == PAGE_STATE_UNUSED || page->WiredCount() > 0)
  18                 return true;
  19
  20         return false;
  21 }
  22
  23
  24 bool
  25 PageCacheLocker::Lock(vm_page* page, bool dontWait)
  26 {
  27         if (_IgnorePage(page))
  28                 return false;
  29
  30         // Grab a reference to this cache.
  31         VMCache* cache = vm_cache_acquire_locked_page_cache(page, dontWait);
  32         if (cache == NULL)
  33                 return false;
  34
  35         if (_IgnorePage(page)) {
  36                 cache->ReleaseRefAndUnlock();
  37                 return false;
  38         }
  39
  40         fPage = page;
  41         return true;
  42 }
  43
  44
  45 void
  46 PageCacheLocker::Unlock()
  47 {
  48         if (fPage == NULL)
  49                 return;
  50
  51         fPage->Cache()->ReleaseRefAndUnlock();
  52
  53         fPage = NULL;
  54 }