PDMAsyncCompletionFileCache.cpp@ 29561

Last change on this file since 29561 was 29250, checked in by vboxsync, 15 years ago
iprt/asm.h: split out asm-math.h, don't include asm-.h from asm.h, don't include asm.h from sup.h. Fixed a couple file headers.
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1	/* $Id: PDMAsyncCompletionFileCache.cpp 29250 2010-05-09 17:53:58Z vboxsync $ */
2	/** @file
3	* PDM Async I/O - Transport data asynchronous in R3 using EMT.
4	* File data cache.
5	*/
6
7	/*
8	* Copyright (C) 2006-2008 Oracle Corporation
9	*
10	* This file is part of VirtualBox Open Source Edition (OSE), as
11	* available from http://www.virtualbox.org. This file is free software;
12	* you can redistribute it and/or modify it under the terms of the GNU
13	* General Public License (GPL) as published by the Free Software
14	* Foundation, in version 2 as it comes in the "COPYING" file of the
15	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
16	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
17	*/
18
19	/** @page pg_pdm_async_completion_cache PDM Async Completion Cache - The file I/O cache
20	* This component implements an I/O cache for file endpoints based on the 2Q cache algorithm.
21	*/
22
23	/*******************************************************************************
24	* Header Files *
25	*******************************************************************************/
26	#define LOG_GROUP LOG_GROUP_PDM_ASYNC_COMPLETION
27	#include <iprt/asm.h>
28	#include <iprt/mem.h>
29	#include <iprt/path.h>
30	#include <VBox/log.h>
31	#include <VBox/stam.h>
32
33	#include "PDMAsyncCompletionFileInternal.h"
34
35	/**
36	* A I/O memory context.
37	*/
38	typedef struct PDMIOMEMCTX
39	{
40	/** Pointer to the scatter/gather list. */
41	PCRTSGSEG paDataSeg;
42	/** Number of segments. */
43	size_t cSegments;
44	/** Current segment we are in. */
45	unsigned iSegIdx;
46	/** Pointer to the current buffer. */
47	uint8_t *pbBuf;
48	/** Number of bytes left in the current buffer. */
49	size_t cbBufLeft;
50	} PDMIOMEMCTX, *PPDMIOMEMCTX;
51
52	#ifdef VBOX_STRICT
53	# define PDMACFILECACHE_IS_CRITSECT_OWNER(Cache) \
54	do \
55	{ \
56	AssertMsg(RTCritSectIsOwner(&Cache->CritSect), \
57	("Thread does not own critical section\n"));\
58	} while(0)
59
60	# define PDMACFILECACHE_EP_IS_SEMRW_WRITE_OWNER(pEpCache) \
61	do \
62	{ \
63	AssertMsg(RTSemRWIsWriteOwner(pEpCache->SemRWEntries), \
64	("Thread is not exclusive owner of the per endpoint RW semaphore\n")); \
65	} while(0)
66
67	# define PDMACFILECACHE_EP_IS_SEMRW_READ_OWNER(pEpCache) \
68	do \
69	{ \
70	AssertMsg(RTSemRWIsReadOwner(pEpCache->SemRWEntries), \
71	("Thread is not read owner of the per endpoint RW semaphore\n")); \
72	} while(0)
73
74	#else
75	# define PDMACFILECACHE_IS_CRITSECT_OWNER(Cache) do { } while(0)
76	# define PDMACFILECACHE_EP_IS_SEMRW_WRITE_OWNER(pEpCache) do { } while(0)
77	# define PDMACFILECACHE_EP_IS_SEMRW_READ_OWNER(pEpCache) do { } while(0)
78	#endif
79
80	/*******************************************************************************
81	* Internal Functions *
82	*******************************************************************************/
83	static void pdmacFileCacheTaskCompleted(PPDMACTASKFILE pTask, void *pvUser, int rc);
84
85	/**
86	* Decrement the reference counter of the given cache entry.
87	*
88	* @returns nothing.
89	* @param pEntry The entry to release.
90	*/
91	DECLINLINE(void) pdmacFileEpCacheEntryRelease(PPDMACFILECACHEENTRY pEntry)
92	{
93	AssertMsg(pEntry->cRefs > 0, ("Trying to release a not referenced entry\n"));
94	ASMAtomicDecU32(&pEntry->cRefs);
95	}
96
97	/**
98	* Increment the reference counter of the given cache entry.
99	*
100	* @returns nothing.
101	* @param pEntry The entry to reference.
102	*/
103	DECLINLINE(void) pdmacFileEpCacheEntryRef(PPDMACFILECACHEENTRY pEntry)
104	{
105	ASMAtomicIncU32(&pEntry->cRefs);
106	}
107
108	/**
109	* Initialize a I/O memory context.
110	*
111	* @returns nothing
112	* @param pIoMemCtx Pointer to a unitialized I/O memory context.
113	* @param paDataSeg Pointer to the S/G list.
114	* @param cSegments Number of segments in the S/G list.
115	*/
116	DECLINLINE(void) pdmIoMemCtxInit(PPDMIOMEMCTX pIoMemCtx, PCRTSGSEG paDataSeg, size_t cSegments)
117	{
118	AssertMsg((cSegments > 0) && paDataSeg, ("Trying to initialize a I/O memory context without a S/G list\n"));
119
120	pIoMemCtx->paDataSeg = paDataSeg;
121	pIoMemCtx->cSegments = cSegments;
122	pIoMemCtx->iSegIdx = 0;
123	pIoMemCtx->pbBuf = (uint8_t *)paDataSeg[0].pvSeg;
124	pIoMemCtx->cbBufLeft = paDataSeg[0].cbSeg;
125	}
126
127	/**
128	* Return a buffer from the I/O memory context.
129	*
130	* @returns Pointer to the buffer
131	* @param pIoMemCtx Pointer to the I/O memory context.
132	* @param pcbData Pointer to the amount of byte requested.
133	* If the current buffer doesn't have enough bytes left
134	* the amount is returned in the variable.
135	*/
136	DECLINLINE(uint8_t ) pdmIoMemCtxGetBuffer(PPDMIOMEMCTX pIoMemCtx, size_t pcbData)
137	{
138	size_t cbData = RT_MIN(*pcbData, pIoMemCtx->cbBufLeft);
139	uint8_t *pbBuf = pIoMemCtx->pbBuf;
140
141	pIoMemCtx->cbBufLeft -= cbData;
142
143	/* Advance to the next segment if required. */
144	if (!pIoMemCtx->cbBufLeft)
145	{
146	pIoMemCtx->iSegIdx++;
147
148	if (RT_UNLIKELY(pIoMemCtx->iSegIdx == pIoMemCtx->cSegments))
149	{
150	pIoMemCtx->cbBufLeft = 0;
151	pIoMemCtx->pbBuf = NULL;
152	}
153	else
154	{
155	pIoMemCtx->pbBuf = (uint8_t *)pIoMemCtx->paDataSeg[pIoMemCtx->iSegIdx].pvSeg;
156	pIoMemCtx->cbBufLeft = pIoMemCtx->paDataSeg[pIoMemCtx->iSegIdx].cbSeg;
157	}
158
159	*pcbData = cbData;
160	}
161	else
162	pIoMemCtx->pbBuf += cbData;
163
164	return pbBuf;
165	}
166
167	#ifdef DEBUG
168	static void pdmacFileCacheValidate(PPDMACFILECACHEGLOBAL pCache)
169	{
170	/* Amount of cached data should never exceed the maximum amount. */
171	AssertMsg(pCache->cbCached <= pCache->cbMax,
172	("Current amount of cached data exceeds maximum\n"));
173
174	/* The amount of cached data in the LRU and FRU list should match cbCached */
175	AssertMsg(pCache->LruRecentlyUsedIn.cbCached + pCache->LruFrequentlyUsed.cbCached == pCache->cbCached,
176	("Amount of cached data doesn't match\n"));
177
178	AssertMsg(pCache->LruRecentlyUsedOut.cbCached <= pCache->cbRecentlyUsedOutMax,
179	("Paged out list exceeds maximum\n"));
180	}
181	#endif
182
183	DECLINLINE(void) pdmacFileCacheLockEnter(PPDMACFILECACHEGLOBAL pCache)
184	{
185	RTCritSectEnter(&pCache->CritSect);
186	#ifdef DEBUG
187	pdmacFileCacheValidate(pCache);
188	#endif
189	}
190
191	DECLINLINE(void) pdmacFileCacheLockLeave(PPDMACFILECACHEGLOBAL pCache)
192	{
193	#ifdef DEBUG
194	pdmacFileCacheValidate(pCache);
195	#endif
196	RTCritSectLeave(&pCache->CritSect);
197	}
198
199	DECLINLINE(void) pdmacFileCacheSub(PPDMACFILECACHEGLOBAL pCache, uint32_t cbAmount)
200	{
201	PDMACFILECACHE_IS_CRITSECT_OWNER(pCache);
202	pCache->cbCached -= cbAmount;
203	}
204
205	DECLINLINE(void) pdmacFileCacheAdd(PPDMACFILECACHEGLOBAL pCache, uint32_t cbAmount)
206	{
207	PDMACFILECACHE_IS_CRITSECT_OWNER(pCache);
208	pCache->cbCached += cbAmount;
209	}
210
211	DECLINLINE(void) pdmacFileCacheListAdd(PPDMACFILELRULIST pList, uint32_t cbAmount)
212	{
213	pList->cbCached += cbAmount;
214	}
215
216	DECLINLINE(void) pdmacFileCacheListSub(PPDMACFILELRULIST pList, uint32_t cbAmount)
217	{
218	pList->cbCached -= cbAmount;
219	}
220
221	#ifdef PDMACFILECACHE_WITH_LRULIST_CHECKS
222	/**
223	* Checks consistency of a LRU list.
224	*
225	* @returns nothing
226	* @param pList The LRU list to check.
227	* @param pNotInList Element which is not allowed to occur in the list.
228	*/
229	static void pdmacFileCacheCheckList(PPDMACFILELRULIST pList, PPDMACFILECACHEENTRY pNotInList)
230	{
231	PPDMACFILECACHEENTRY pCurr = pList->pHead;
232
233	/* Check that there are no double entries and no cycles in the list. */
234	while (pCurr)
235	{
236	PPDMACFILECACHEENTRY pNext = pCurr->pNext;
237
238	while (pNext)
239	{
240	AssertMsg(pCurr != pNext,
241	("Entry %#p is at least two times in list %#p or there is a cycle in the list\n",
242	pCurr, pList));
243	pNext = pNext->pNext;
244	}
245
246	AssertMsg(pCurr != pNotInList, ("Not allowed entry %#p is in list\n", pCurr));
247
248	if (!pCurr->pNext)
249	AssertMsg(pCurr == pList->pTail, ("End of list reached but last element is not list tail\n"));
250
251	pCurr = pCurr->pNext;
252	}
253	}
254	#endif
255
256	/**
257	* Unlinks a cache entry from the LRU list it is assigned to.
258	*
259	* @returns nothing.
260	* @param pEntry The entry to unlink.
261	*/
262	static void pdmacFileCacheEntryRemoveFromList(PPDMACFILECACHEENTRY pEntry)
263	{
264	PPDMACFILELRULIST pList = pEntry->pList;
265	PPDMACFILECACHEENTRY pPrev, pNext;
266
267	LogFlowFunc((": Deleting entry %#p from list %#p\n", pEntry, pList));
268
269	AssertPtr(pList);
270
271	#ifdef PDMACFILECACHE_WITH_LRULIST_CHECKS
272	pdmacFileCacheCheckList(pList, NULL);
273	#endif
274
275	pPrev = pEntry->pPrev;
276	pNext = pEntry->pNext;
277
278	AssertMsg(pEntry != pPrev, ("Entry links to itself as previous element\n"));
279	AssertMsg(pEntry != pNext, ("Entry links to itself as next element\n"));
280
281	if (pPrev)
282	pPrev->pNext = pNext;
283	else
284	{
285	pList->pHead = pNext;
286
287	if (pNext)
288	pNext->pPrev = NULL;
289	}
290
291	if (pNext)
292	pNext->pPrev = pPrev;
293	else
294	{
295	pList->pTail = pPrev;
296
297	if (pPrev)
298	pPrev->pNext = NULL;
299	}
300
301	pEntry->pList = NULL;
302	pEntry->pPrev = NULL;
303	pEntry->pNext = NULL;
304	pdmacFileCacheListSub(pList, pEntry->cbData);
305	#ifdef PDMACFILECACHE_WITH_LRULIST_CHECKS
306	pdmacFileCacheCheckList(pList, pEntry);
307	#endif
308	}
309
310	/**
311	* Adds a cache entry to the given LRU list unlinking it from the currently
312	* assigned list if needed.
313	*
314	* @returns nothing.
315	* @param pList List to the add entry to.
316	* @param pEntry Entry to add.
317	*/
318	static void pdmacFileCacheEntryAddToList(PPDMACFILELRULIST pList, PPDMACFILECACHEENTRY pEntry)
319	{
320	LogFlowFunc((": Adding entry %#p to list %#p\n", pEntry, pList));
321	#ifdef PDMACFILECACHE_WITH_LRULIST_CHECKS
322	pdmacFileCacheCheckList(pList, NULL);
323	#endif
324
325	/* Remove from old list if needed */
326	if (pEntry->pList)
327	pdmacFileCacheEntryRemoveFromList(pEntry);
328
329	pEntry->pNext = pList->pHead;
330	if (pList->pHead)
331	pList->pHead->pPrev = pEntry;
332	else
333	{
334	Assert(!pList->pTail);
335	pList->pTail = pEntry;
336	}
337
338	pEntry->pPrev = NULL;
339	pList->pHead = pEntry;
340	pdmacFileCacheListAdd(pList, pEntry->cbData);
341	pEntry->pList = pList;
342	#ifdef PDMACFILECACHE_WITH_LRULIST_CHECKS
343	pdmacFileCacheCheckList(pList, NULL);
344	#endif
345	}
346
347	/**
348	* Destroys a LRU list freeing all entries.
349	*
350	* @returns nothing
351	* @param pList Pointer to the LRU list to destroy.
352	*
353	* @note The caller must own the critical section of the cache.
354	*/
355	static void pdmacFileCacheDestroyList(PPDMACFILELRULIST pList)
356	{
357	while (pList->pHead)
358	{
359	PPDMACFILECACHEENTRY pEntry = pList->pHead;
360
361	pList->pHead = pEntry->pNext;
362
363	AssertMsg(!(pEntry->fFlags & (PDMACFILECACHE_ENTRY_IO_IN_PROGRESS \| PDMACFILECACHE_ENTRY_IS_DIRTY)),
364	("Entry is dirty and/or still in progress fFlags=%#x\n", pEntry->fFlags));
365
366	RTMemPageFree(pEntry->pbData, pEntry->cbData);
367	RTMemFree(pEntry);
368	}
369	}
370
371	/**
372	* Tries to remove the given amount of bytes from a given list in the cache
373	* moving the entries to one of the given ghosts lists
374	*
375	* @returns Amount of data which could be freed.
376	* @param pCache Pointer to the global cache data.
377	* @param cbData The amount of the data to free.
378	* @param pListSrc The source list to evict data from.
379	* @param pGhostListSrc The ghost list removed entries should be moved to
380	* NULL if the entry should be freed.
381	* @param fReuseBuffer Flag whether a buffer should be reused if it has the same size
382	* @param ppbBuf Where to store the address of the buffer if an entry with the
383	* same size was found and fReuseBuffer is true.
384	*
385	* @note This function may return fewer bytes than requested because entries
386	* may be marked as non evictable if they are used for I/O at the
387	* moment.
388	*/
389	static size_t pdmacFileCacheEvictPagesFrom(PPDMACFILECACHEGLOBAL pCache, size_t cbData,
390	PPDMACFILELRULIST pListSrc, PPDMACFILELRULIST pGhostListDst,
391	bool fReuseBuffer, uint8_t **ppbBuffer)
392	{
393	size_t cbEvicted = 0;
394
395	PDMACFILECACHE_IS_CRITSECT_OWNER(pCache);
396
397	AssertMsg(cbData > 0, ("Evicting 0 bytes not possible\n"));
398	AssertMsg( !pGhostListDst
399	\|\| (pGhostListDst == &pCache->LruRecentlyUsedOut),
400	("Destination list must be NULL or the recently used but paged out list\n"));
401
402	if (fReuseBuffer)
403	{
404	AssertPtr(ppbBuffer);
405	*ppbBuffer = NULL;
406	}
407
408	/* Start deleting from the tail. */
409	PPDMACFILECACHEENTRY pEntry = pListSrc->pTail;
410
411	while ((cbEvicted < cbData) && pEntry)
412	{
413	PPDMACFILECACHEENTRY pCurr = pEntry;
414
415	pEntry = pEntry->pPrev;
416
417	/* We can't evict pages which are currently in progress or dirty but not in progress */
418	if ( !(pCurr->fFlags & PDMACFILECACHE_NOT_EVICTABLE)
419	&& (ASMAtomicReadU32(&pCurr->cRefs) == 0))
420	{
421	/* Ok eviction candidate. Grab the endpoint semaphore and check again
422	* because somebody else might have raced us. */
423	PPDMACFILEENDPOINTCACHE pEndpointCache = &pCurr->pEndpoint->DataCache;
424	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
425
426	if (!(pCurr->fFlags & PDMACFILECACHE_NOT_EVICTABLE)
427	&& (ASMAtomicReadU32(&pCurr->cRefs) == 0))
428	{
429	LogFlow(("Evicting entry %#p (%u bytes)\n", pCurr, pCurr->cbData));
430
431	if (fReuseBuffer && (pCurr->cbData == cbData))
432	{
433	STAM_COUNTER_INC(&pCache->StatBuffersReused);
434	*ppbBuffer = pCurr->pbData;
435	}
436	else if (pCurr->pbData)
437	RTMemPageFree(pCurr->pbData, pCurr->cbData);
438
439	pCurr->pbData = NULL;
440	cbEvicted += pCurr->cbData;
441
442	pdmacFileCacheEntryRemoveFromList(pCurr);
443	pdmacFileCacheSub(pCache, pCurr->cbData);
444
445	if (pGhostListDst)
446	{
447	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
448
449	PPDMACFILECACHEENTRY pGhostEntFree = pGhostListDst->pTail;
450
451	/* We have to remove the last entries from the paged out list. */
452	while ( ((pGhostListDst->cbCached + pCurr->cbData) > pCache->cbRecentlyUsedOutMax)
453	&& pGhostEntFree)
454	{
455	PPDMACFILECACHEENTRY pFree = pGhostEntFree;
456	PPDMACFILEENDPOINTCACHE pEndpointCacheFree = &pFree->pEndpoint->DataCache;
457
458	pGhostEntFree = pGhostEntFree->pPrev;
459
460	RTSemRWRequestWrite(pEndpointCacheFree->SemRWEntries, RT_INDEFINITE_WAIT);
461
462	if (ASMAtomicReadU32(&pFree->cRefs) == 0)
463	{
464	pdmacFileCacheEntryRemoveFromList(pFree);
465
466	STAM_PROFILE_ADV_START(&pCache->StatTreeRemove, Cache);
467	RTAvlrFileOffsetRemove(pEndpointCacheFree->pTree, pFree->Core.Key);
468	STAM_PROFILE_ADV_STOP(&pCache->StatTreeRemove, Cache);
469
470	RTMemFree(pFree);
471	}
472
473	RTSemRWReleaseWrite(pEndpointCacheFree->SemRWEntries);
474	}
475
476	if (pGhostListDst->cbCached + pCurr->cbData > pCache->cbRecentlyUsedOutMax)
477	{
478	/* Couldn't remove enough entries. Delete */
479	STAM_PROFILE_ADV_START(&pCache->StatTreeRemove, Cache);
480	RTAvlrFileOffsetRemove(pCurr->pEndpoint->DataCache.pTree, pCurr->Core.Key);
481	STAM_PROFILE_ADV_STOP(&pCache->StatTreeRemove, Cache);
482
483	RTMemFree(pCurr);
484	}
485	else
486	pdmacFileCacheEntryAddToList(pGhostListDst, pCurr);
487	}
488	else
489	{
490	/* Delete the entry from the AVL tree it is assigned to. */
491	STAM_PROFILE_ADV_START(&pCache->StatTreeRemove, Cache);
492	RTAvlrFileOffsetRemove(pCurr->pEndpoint->DataCache.pTree, pCurr->Core.Key);
493	STAM_PROFILE_ADV_STOP(&pCache->StatTreeRemove, Cache);
494
495	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
496	RTMemFree(pCurr);
497	}
498	}
499
500	}
501	else
502	LogFlow(("Entry %#p (%u bytes) is still in progress and can't be evicted\n", pCurr, pCurr->cbData));
503	}
504
505	return cbEvicted;
506	}
507
508	static bool pdmacFileCacheReclaim(PPDMACFILECACHEGLOBAL pCache, size_t cbData, bool fReuseBuffer, uint8_t **ppbBuffer)
509	{
510	size_t cbRemoved = 0;
511
512	if ((pCache->cbCached + cbData) < pCache->cbMax)
513	return true;
514	else if ((pCache->LruRecentlyUsedIn.cbCached + cbData) > pCache->cbRecentlyUsedInMax)
515	{
516	/* Try to evict as many bytes as possible from A1in */
517	cbRemoved = pdmacFileCacheEvictPagesFrom(pCache, cbData, &pCache->LruRecentlyUsedIn,
518	&pCache->LruRecentlyUsedOut, fReuseBuffer, ppbBuffer);
519
520	/*
521	* If it was not possible to remove enough entries
522	* try the frequently accessed cache.
523	*/
524	if (cbRemoved < cbData)
525	{
526	Assert(!fReuseBuffer \|\| !ppbBuffer); / It is not possible that we got a buffer with the correct size but we didn't freed enough data. */
527
528	/*
529	* If we removed something we can't pass the reuse buffer flag anymore because
530	* we don't need to evict that much data
531	*/
532	if (!cbRemoved)
533	cbRemoved += pdmacFileCacheEvictPagesFrom(pCache, cbData, &pCache->LruFrequentlyUsed,
534	NULL, fReuseBuffer, ppbBuffer);
535	else
536	cbRemoved += pdmacFileCacheEvictPagesFrom(pCache, cbData - cbRemoved, &pCache->LruFrequentlyUsed,
537	NULL, false, NULL);
538	}
539	}
540	else
541	{
542	/* We have to remove entries from frequently access list. */
543	cbRemoved = pdmacFileCacheEvictPagesFrom(pCache, cbData, &pCache->LruFrequentlyUsed,
544	NULL, fReuseBuffer, ppbBuffer);
545	}
546
547	LogFlowFunc((": removed %u bytes, requested %u\n", cbRemoved, cbData));
548	return (cbRemoved >= cbData);
549	}
550
551	/**
552	* Initiates a read I/O task for the given entry.
553	*
554	* @returns nothing.
555	* @param pEntry The entry to fetch the data to.
556	*/
557	static void pdmacFileCacheReadFromEndpoint(PPDMACFILECACHEENTRY pEntry)
558	{
559	LogFlowFunc((": Reading data into cache entry %#p\n", pEntry));
560
561	/* Make sure no one evicts the entry while it is accessed. */
562	pEntry->fFlags \|= PDMACFILECACHE_ENTRY_IO_IN_PROGRESS;
563
564	PPDMACTASKFILE pIoTask = pdmacFileTaskAlloc(pEntry->pEndpoint);
565	AssertPtr(pIoTask);
566
567	AssertMsg(pEntry->pbData, ("Entry is in ghost state\n"));
568
569	pIoTask->pEndpoint = pEntry->pEndpoint;
570	pIoTask->enmTransferType = PDMACTASKFILETRANSFER_READ;
571	pIoTask->Off = pEntry->Core.Key;
572	pIoTask->DataSeg.cbSeg = pEntry->cbData;
573	pIoTask->DataSeg.pvSeg = pEntry->pbData;
574	pIoTask->pvUser = pEntry;
575	pIoTask->pfnCompleted = pdmacFileCacheTaskCompleted;
576
577	/* Send it off to the I/O manager. */
578	pdmacFileEpAddTask(pEntry->pEndpoint, pIoTask);
579	}
580
581	/**
582	* Initiates a write I/O task for the given entry.
583	*
584	* @returns nothing.
585	* @param pEntry The entry to read the data from.
586	*/
587	static void pdmacFileCacheWriteToEndpoint(PPDMACFILECACHEENTRY pEntry)
588	{
589	LogFlowFunc((": Writing data from cache entry %#p\n", pEntry));
590
591	/* Make sure no one evicts the entry while it is accessed. */
592	pEntry->fFlags \|= PDMACFILECACHE_ENTRY_IO_IN_PROGRESS;
593
594	PPDMACTASKFILE pIoTask = pdmacFileTaskAlloc(pEntry->pEndpoint);
595	AssertPtr(pIoTask);
596
597	AssertMsg(pEntry->pbData, ("Entry is in ghost state\n"));
598
599	pIoTask->pEndpoint = pEntry->pEndpoint;
600	pIoTask->enmTransferType = PDMACTASKFILETRANSFER_WRITE;
601	pIoTask->Off = pEntry->Core.Key;
602	pIoTask->DataSeg.cbSeg = pEntry->cbData;
603	pIoTask->DataSeg.pvSeg = pEntry->pbData;
604	pIoTask->pvUser = pEntry;
605	pIoTask->pfnCompleted = pdmacFileCacheTaskCompleted;
606
607	/* Send it off to the I/O manager. */
608	pdmacFileEpAddTask(pEntry->pEndpoint, pIoTask);
609	}
610
611	/**
612	* Commit a single dirty entry to the endpoint
613	*
614	* @returns nothing
615	* @param pEntry The entry to commit.
616	*/
617	static void pdmacFileCacheEntryCommit(PPDMACFILEENDPOINTCACHE pEndpointCache, PPDMACFILECACHEENTRY pEntry)
618	{
619	NOREF(pEndpointCache);
620	AssertMsg( (pEntry->fFlags & PDMACFILECACHE_ENTRY_IS_DIRTY)
621	&& !(pEntry->fFlags & PDMACFILECACHE_ENTRY_IO_IN_PROGRESS),
622	("Invalid flags set for entry %#p\n", pEntry));
623
624	pdmacFileCacheWriteToEndpoint(pEntry);
625	}
626
627	/**
628	* Commit all dirty entries for a single endpoint.
629	*
630	* @returns nothing.
631	* @param pEndpointCache The endpoint cache to commit.
632	*/
633	static void pdmacFileCacheEndpointCommit(PPDMACFILEENDPOINTCACHE pEndpointCache)
634	{
635	uint32_t cbCommitted = 0;
636	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
637
638	/* The list is moved to a new header to reduce locking overhead. */
639	RTLISTNODE ListDirtyNotCommitted;
640	RTSPINLOCKTMP Tmp;
641
642	RTListInit(&ListDirtyNotCommitted);
643	RTSpinlockAcquire(pEndpointCache->LockList, &Tmp);
644	RTListMove(&ListDirtyNotCommitted, &pEndpointCache->ListDirtyNotCommitted);
645	RTSpinlockRelease(pEndpointCache->LockList, &Tmp);
646
647	if (!RTListIsEmpty(&ListDirtyNotCommitted))
648	{
649	PPDMACFILECACHEENTRY pEntry = RTListNodeGetFirst(&ListDirtyNotCommitted,
650	PDMACFILECACHEENTRY,
651	NodeNotCommitted);
652
653	while (!RTListNodeIsLast(&ListDirtyNotCommitted, &pEntry->NodeNotCommitted))
654	{
655	PPDMACFILECACHEENTRY pNext = RTListNodeGetNext(&pEntry->NodeNotCommitted, PDMACFILECACHEENTRY,
656	NodeNotCommitted);
657	pdmacFileCacheEntryCommit(pEndpointCache, pEntry);
658	cbCommitted += pEntry->cbData;
659	RTListNodeRemove(&pEntry->NodeNotCommitted);
660	pEntry = pNext;
661	}
662
663	/* Commit the last endpoint */
664	Assert(RTListNodeIsLast(&ListDirtyNotCommitted, &pEntry->NodeNotCommitted));
665	pdmacFileCacheEntryCommit(pEndpointCache, pEntry);
666	RTListNodeRemove(&pEntry->NodeNotCommitted);
667	AssertMsg(RTListIsEmpty(&ListDirtyNotCommitted),
668	("Committed all entries but list is not empty\n"));
669	}
670
671	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
672	AssertMsg(pEndpointCache->pCache->cbDirty >= cbCommitted,
673	("Number of committed bytes exceeds number of dirty bytes\n"));
674	ASMAtomicSubU32(&pEndpointCache->pCache->cbDirty, cbCommitted);
675	}
676
677	/**
678	* Commit all dirty entries in the cache.
679	*
680	* @returns nothing.
681	* @param pCache The global cache instance.
682	*/
683	static void pdmacFileCacheCommitDirtyEntries(PPDMACFILECACHEGLOBAL pCache)
684	{
685	bool fCommitInProgress = ASMAtomicXchgBool(&pCache->fCommitInProgress, true);
686
687	if (!fCommitInProgress)
688	{
689	pdmacFileCacheLockEnter(pCache);
690	Assert(!RTListIsEmpty(&pCache->ListEndpoints));
691
692	PPDMACFILEENDPOINTCACHE pEndpointCache = RTListNodeGetFirst(&pCache->ListEndpoints,
693	PDMACFILEENDPOINTCACHE,
694	NodeCacheEndpoint);
695	AssertPtr(pEndpointCache);
696
697	while (!RTListNodeIsLast(&pCache->ListEndpoints, &pEndpointCache->NodeCacheEndpoint))
698	{
699	pdmacFileCacheEndpointCommit(pEndpointCache);
700
701	pEndpointCache = RTListNodeGetNext(&pEndpointCache->NodeCacheEndpoint, PDMACFILEENDPOINTCACHE,
702	NodeCacheEndpoint);
703	}
704
705	/* Commit the last endpoint */
706	Assert(RTListNodeIsLast(&pCache->ListEndpoints, &pEndpointCache->NodeCacheEndpoint));
707	pdmacFileCacheEndpointCommit(pEndpointCache);
708
709	pdmacFileCacheLockLeave(pCache);
710	ASMAtomicWriteBool(&pCache->fCommitInProgress, false);
711	}
712	}
713
714	/**
715	* Adds the given entry as a dirty to the cache.
716	*
717	* @returns Flag whether the amount of dirty bytes in the cache exceeds the threshold
718	* @param pEndpointCache The endpoint cache the entry belongs to.
719	* @param pEntry The entry to add.
720	*/
721	static bool pdmacFileCacheAddDirtyEntry(PPDMACFILEENDPOINTCACHE pEndpointCache, PPDMACFILECACHEENTRY pEntry)
722	{
723	bool fDirtyBytesExceeded = false;
724	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
725
726	/* If the commit timer is disabled we commit right away. */
727	if (pCache->u32CommitTimeoutMs == 0)
728	{
729	pEntry->fFlags \|= PDMACFILECACHE_ENTRY_IS_DIRTY;
730	pdmacFileCacheEntryCommit(pEndpointCache, pEntry);
731	}
732	else if (!(pEntry->fFlags & PDMACFILECACHE_ENTRY_IS_DIRTY))
733	{
734	pEntry->fFlags \|= PDMACFILECACHE_ENTRY_IS_DIRTY;
735
736	RTSPINLOCKTMP Tmp;
737	RTSpinlockAcquire(pEndpointCache->LockList, &Tmp);
738	RTListAppend(&pEndpointCache->ListDirtyNotCommitted, &pEntry->NodeNotCommitted);
739	RTSpinlockRelease(pEndpointCache->LockList, &Tmp);
740
741	uint32_t cbDirty = ASMAtomicAddU32(&pCache->cbDirty, pEntry->cbData);
742
743	fDirtyBytesExceeded = (cbDirty >= pCache->cbCommitDirtyThreshold);
744	}
745
746	return fDirtyBytesExceeded;
747	}
748
749
750	/**
751	* Completes a task segment freeing all ressources and completes the task handle
752	* if everything was transfered.
753	*
754	* @returns Next task segment handle.
755	* @param pTaskSeg Task segment to complete.
756	* @param rc Status code to set.
757	*/
758	static PPDMACFILETASKSEG pdmacFileCacheTaskComplete(PPDMACFILETASKSEG pTaskSeg, int rc)
759	{
760	PPDMACFILETASKSEG pNext = pTaskSeg->pNext;
761	PPDMASYNCCOMPLETIONTASKFILE pTaskFile = pTaskSeg->pTask;
762
763	if (RT_FAILURE(rc))
764	ASMAtomicCmpXchgS32(&pTaskFile->rc, rc, VINF_SUCCESS);
765
766	uint32_t uOld = ASMAtomicSubS32(&pTaskFile->cbTransferLeft, pTaskSeg->cbTransfer);
767	AssertMsg(uOld >= pTaskSeg->cbTransfer, ("New value would overflow\n"));
768	if (!(uOld - pTaskSeg->cbTransfer)
769	&& !ASMAtomicXchgBool(&pTaskFile->fCompleted, true))
770	pdmR3AsyncCompletionCompleteTask(&pTaskFile->Core, pTaskFile->rc, true);
771
772	RTMemFree(pTaskSeg);
773
774	return pNext;
775	}
776
777	/**
778	* Completion callback for I/O tasks.
779	*
780	* @returns nothing.
781	* @param pTask The completed task.
782	* @param pvUser Opaque user data.
783	* @param rc Status code of the completed request.
784	*/
785	static void pdmacFileCacheTaskCompleted(PPDMACTASKFILE pTask, void *pvUser, int rc)
786	{
787	PPDMACFILECACHEENTRY pEntry = (PPDMACFILECACHEENTRY)pvUser;
788	PPDMACFILECACHEGLOBAL pCache = pEntry->pCache;
789	PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint = pEntry->pEndpoint;
790	PPDMACFILEENDPOINTCACHE pEndpointCache = &pEndpoint->DataCache;
791
792	/* Reference the entry now as we are clearing the I/O in progres flag
793	* which protects the entry till now. */
794	pdmacFileEpCacheEntryRef(pEntry);
795
796	RTSemRWRequestWrite(pEndpoint->DataCache.SemRWEntries, RT_INDEFINITE_WAIT);
797	pEntry->fFlags &= ~PDMACFILECACHE_ENTRY_IO_IN_PROGRESS;
798
799	/* Process waiting segment list. The data in entry might have changed inbetween. */
800	bool fDirty = false;
801	PPDMACFILETASKSEG pComplete = pEntry->pWaitingHead;
802	PPDMACFILETASKSEG pCurr = pComplete;
803
804	AssertMsg((pCurr && pEntry->pWaitingTail) \|\| (!pCurr && !pEntry->pWaitingTail),
805	("The list tail was not updated correctly\n"));
806	pEntry->pWaitingTail = NULL;
807	pEntry->pWaitingHead = NULL;
808
809	if (pTask->enmTransferType == PDMACTASKFILETRANSFER_WRITE)
810	{
811	/*
812	* An error here is difficult to handle as the original request completed already.
813	* The error is logged for now and the VM is paused.
814	* If the user continues the entry is written again in the hope
815	* the user fixed the problem and the next write succeeds.
816	*/
817	/** @todo r=aeichner: This solution doesn't work
818	* The user will get the message but the VM will hang afterwards
819	* VMR3Suspend() returns when the VM is suspended but suspending
820	* the VM will reopen the images readonly in DrvVD. They are closed first
821	* which will close the endpoints. This will block EMT while the
822	* I/O manager processes the close request but the IO manager is stuck
823	* in the VMR3Suspend call and can't process the request.
824	* Another problem is that closing the VM means flushing the cache
825	* but the entry failed and will probably fail again.
826	* No idea so far how to solve this problem... but the user gets informed
827	* at least.
828	*/
829	if (RT_FAILURE(rc))
830	{
831	LogRel(("I/O cache: Error while writing entry at offset %RTfoff (%u bytes) to file \"%s\"\n",
832	pEntry->Core.Key, pEntry->cbData, pEndpoint->Core.pszUri));
833
834	rc = VMSetRuntimeError(pEndpoint->Core.pEpClass->pVM, 0, "CACHE_IOERR",
835	N_("The I/O cache encountered an error while updating data in file \"%s\" (rc=%Rrc). Make sure there is enough free space on the disk and that the disk is working properly. Operation can be resumed afterwards."), pEndpoint->Core.pszUri, rc);
836	AssertRC(rc);
837	rc = VMR3Suspend(pEndpoint->Core.pEpClass->pVM);
838	}
839	else
840	{
841	pEntry->fFlags &= ~PDMACFILECACHE_ENTRY_IS_DIRTY;
842
843	while (pCurr)
844	{
845	AssertMsg(pCurr->fWrite, ("Completed write entries should never have read tasks attached\n"));
846
847	memcpy(pEntry->pbData + pCurr->uBufOffset, pCurr->pvBuf, pCurr->cbTransfer);
848	fDirty = true;
849
850	pCurr = pCurr->pNext;
851	}
852	}
853	}
854	else
855	{
856	AssertMsg(pTask->enmTransferType == PDMACTASKFILETRANSFER_READ, ("Invalid transfer type\n"));
857	AssertMsg(!(pEntry->fFlags & PDMACFILECACHE_ENTRY_IS_DIRTY),
858	("Invalid flags set\n"));
859
860	while (pCurr)
861	{
862	if (pCurr->fWrite)
863	{
864	memcpy(pEntry->pbData + pCurr->uBufOffset, pCurr->pvBuf, pCurr->cbTransfer);
865	fDirty = true;
866	}
867	else
868	memcpy(pCurr->pvBuf, pEntry->pbData + pCurr->uBufOffset, pCurr->cbTransfer);
869
870	pCurr = pCurr->pNext;
871	}
872	}
873
874	bool fCommit = false;
875	if (fDirty)
876	fCommit = pdmacFileCacheAddDirtyEntry(pEndpointCache, pEntry);
877
878	RTSemRWReleaseWrite(pEndpoint->DataCache.SemRWEntries);
879
880	/* Dereference so that it isn't protected anymore except we issued anyother write for it. */
881	pdmacFileEpCacheEntryRelease(pEntry);
882
883	if (fCommit)
884	pdmacFileCacheCommitDirtyEntries(pCache);
885
886	/* Complete waiters now. */
887	while (pComplete)
888	pComplete = pdmacFileCacheTaskComplete(pComplete, rc);
889	}
890
891	/**
892	* Commit timer callback.
893	*/
894	static void pdmacFileCacheCommitTimerCallback(PVM pVM, PTMTIMER pTimer, void *pvUser)
895	{
896	PPDMASYNCCOMPLETIONEPCLASSFILE pClassFile = (PPDMASYNCCOMPLETIONEPCLASSFILE)pvUser;
897	PPDMACFILECACHEGLOBAL pCache = &pClassFile->Cache;
898
899	LogFlowFunc(("Commit interval expired, commiting dirty entries\n"));
900
901	if (ASMAtomicReadU32(&pCache->cbDirty) > 0)
902	pdmacFileCacheCommitDirtyEntries(pCache);
903
904	TMTimerSetMillies(pTimer, pCache->u32CommitTimeoutMs);
905	LogFlowFunc(("Entries committed, going to sleep\n"));
906	}
907
908	/**
909	* Initializies the I/O cache.
910	*
911	* returns VBox status code.
912	* @param pClassFile The global class data for file endpoints.
913	* @param pCfgNode CFGM node to query configuration data from.
914	*/
915	int pdmacFileCacheInit(PPDMASYNCCOMPLETIONEPCLASSFILE pClassFile, PCFGMNODE pCfgNode)
916	{
917	int rc = VINF_SUCCESS;
918	PPDMACFILECACHEGLOBAL pCache = &pClassFile->Cache;
919
920	rc = CFGMR3QueryU32Def(pCfgNode, "CacheSize", &pCache->cbMax, 5 * _1M);
921	AssertLogRelRCReturn(rc, rc);
922
923	RTListInit(&pCache->ListEndpoints);
924	pCache->cRefs = 0;
925	pCache->cbCached = 0;
926	pCache->fCommitInProgress = 0;
927	LogFlowFunc((": Maximum number of bytes cached %u\n", pCache->cbMax));
928
929	/* Initialize members */
930	pCache->LruRecentlyUsedIn.pHead = NULL;
931	pCache->LruRecentlyUsedIn.pTail = NULL;
932	pCache->LruRecentlyUsedIn.cbCached = 0;
933
934	pCache->LruRecentlyUsedOut.pHead = NULL;
935	pCache->LruRecentlyUsedOut.pTail = NULL;
936	pCache->LruRecentlyUsedOut.cbCached = 0;
937
938	pCache->LruFrequentlyUsed.pHead = NULL;
939	pCache->LruFrequentlyUsed.pTail = NULL;
940	pCache->LruFrequentlyUsed.cbCached = 0;
941
942	pCache->cbRecentlyUsedInMax = (pCache->cbMax / 100) * 25; /* 25% of the buffer size */
943	pCache->cbRecentlyUsedOutMax = (pCache->cbMax / 100) * 50; /* 50% of the buffer size */
944	LogFlowFunc((": cbRecentlyUsedInMax=%u cbRecentlyUsedOutMax=%u\n", pCache->cbRecentlyUsedInMax, pCache->cbRecentlyUsedOutMax));
945
946	/** @todo r=aeichner: Experiment to find optimal default values */
947	rc = CFGMR3QueryU32Def(pCfgNode, "CacheCommitIntervalMs", &pCache->u32CommitTimeoutMs, 10000 /* 10sec */);
948	AssertLogRelRCReturn(rc, rc);
949	rc = CFGMR3QueryU32(pCfgNode, "CacheCommitThreshold", &pCache->cbCommitDirtyThreshold);
950	if ( rc == VERR_CFGM_VALUE_NOT_FOUND
951	\|\| rc == VERR_CFGM_NO_PARENT)
952	{
953	/* Start committing after 50% of the cache are dirty */
954	pCache->cbCommitDirtyThreshold = pCache->cbMax / 2;
955	}
956	else
957	return rc;
958
959	STAMR3Register(pClassFile->Core.pVM, &pCache->cbMax,
960	STAMTYPE_U32, STAMVISIBILITY_ALWAYS,
961	"/PDM/AsyncCompletion/File/cbMax",
962	STAMUNIT_BYTES,
963	"Maximum cache size");
964	STAMR3Register(pClassFile->Core.pVM, &pCache->cbCached,
965	STAMTYPE_U32, STAMVISIBILITY_ALWAYS,
966	"/PDM/AsyncCompletion/File/cbCached",
967	STAMUNIT_BYTES,
968	"Currently used cache");
969	STAMR3Register(pClassFile->Core.pVM, &pCache->LruRecentlyUsedIn.cbCached,
970	STAMTYPE_U32, STAMVISIBILITY_ALWAYS,
971	"/PDM/AsyncCompletion/File/cbCachedMruIn",
972	STAMUNIT_BYTES,
973	"Number of bytes cached in MRU list");
974	STAMR3Register(pClassFile->Core.pVM, &pCache->LruRecentlyUsedOut.cbCached,
975	STAMTYPE_U32, STAMVISIBILITY_ALWAYS,
976	"/PDM/AsyncCompletion/File/cbCachedMruOut",
977	STAMUNIT_BYTES,
978	"Number of bytes cached in FRU list");
979	STAMR3Register(pClassFile->Core.pVM, &pCache->LruFrequentlyUsed.cbCached,
980	STAMTYPE_U32, STAMVISIBILITY_ALWAYS,
981	"/PDM/AsyncCompletion/File/cbCachedFru",
982	STAMUNIT_BYTES,
983	"Number of bytes cached in FRU ghost list");
984
985	#ifdef VBOX_WITH_STATISTICS
986	STAMR3Register(pClassFile->Core.pVM, &pCache->cHits,
987	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
988	"/PDM/AsyncCompletion/File/CacheHits",
989	STAMUNIT_COUNT, "Number of hits in the cache");
990	STAMR3Register(pClassFile->Core.pVM, &pCache->cPartialHits,
991	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
992	"/PDM/AsyncCompletion/File/CachePartialHits",
993	STAMUNIT_COUNT, "Number of partial hits in the cache");
994	STAMR3Register(pClassFile->Core.pVM, &pCache->cMisses,
995	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
996	"/PDM/AsyncCompletion/File/CacheMisses",
997	STAMUNIT_COUNT, "Number of misses when accessing the cache");
998	STAMR3Register(pClassFile->Core.pVM, &pCache->StatRead,
999	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
1000	"/PDM/AsyncCompletion/File/CacheRead",
1001	STAMUNIT_BYTES, "Number of bytes read from the cache");
1002	STAMR3Register(pClassFile->Core.pVM, &pCache->StatWritten,
1003	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
1004	"/PDM/AsyncCompletion/File/CacheWritten",
1005	STAMUNIT_BYTES, "Number of bytes written to the cache");
1006	STAMR3Register(pClassFile->Core.pVM, &pCache->StatTreeGet,
1007	STAMTYPE_PROFILE_ADV, STAMVISIBILITY_ALWAYS,
1008	"/PDM/AsyncCompletion/File/CacheTreeGet",
1009	STAMUNIT_TICKS_PER_CALL, "Time taken to access an entry in the tree");
1010	STAMR3Register(pClassFile->Core.pVM, &pCache->StatTreeInsert,
1011	STAMTYPE_PROFILE_ADV, STAMVISIBILITY_ALWAYS,
1012	"/PDM/AsyncCompletion/File/CacheTreeInsert",
1013	STAMUNIT_TICKS_PER_CALL, "Time taken to insert an entry in the tree");
1014	STAMR3Register(pClassFile->Core.pVM, &pCache->StatTreeRemove,
1015	STAMTYPE_PROFILE_ADV, STAMVISIBILITY_ALWAYS,
1016	"/PDM/AsyncCompletion/File/CacheTreeRemove",
1017	STAMUNIT_TICKS_PER_CALL, "Time taken to remove an entry an the tree");
1018	STAMR3Register(pClassFile->Core.pVM, &pCache->StatBuffersReused,
1019	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
1020	"/PDM/AsyncCompletion/File/CacheBuffersReused",
1021	STAMUNIT_COUNT, "Number of times a buffer could be reused");
1022	#endif
1023
1024	/* Initialize the critical section */
1025	rc = RTCritSectInit(&pCache->CritSect);
1026
1027	if (RT_SUCCESS(rc))
1028	{
1029	/* Create the commit timer */
1030	if (pCache->u32CommitTimeoutMs > 0)
1031	rc = TMR3TimerCreateInternal(pClassFile->Core.pVM, TMCLOCK_REAL,
1032	pdmacFileCacheCommitTimerCallback,
1033	pClassFile,
1034	"Cache-Commit",
1035	&pClassFile->Cache.pTimerCommit);
1036
1037	if (RT_SUCCESS(rc))
1038	{
1039	LogRel(("AIOMgr: Cache successfully initialised. Cache size is %u bytes\n", pCache->cbMax));
1040	LogRel(("AIOMgr: Cache commit interval is %u ms\n", pCache->u32CommitTimeoutMs));
1041	LogRel(("AIOMgr: Cache commit threshold is %u bytes\n", pCache->cbCommitDirtyThreshold));
1042	return VINF_SUCCESS;
1043	}
1044
1045	RTCritSectDelete(&pCache->CritSect);
1046	}
1047
1048	return rc;
1049	}
1050
1051	/**
1052	* Destroysthe cache freeing all data.
1053	*
1054	* returns nothing.
1055	* @param pClassFile The global class data for file endpoints.
1056	*/
1057	void pdmacFileCacheDestroy(PPDMASYNCCOMPLETIONEPCLASSFILE pClassFile)
1058	{
1059	PPDMACFILECACHEGLOBAL pCache = &pClassFile->Cache;
1060
1061	/* Make sure no one else uses the cache now */
1062	pdmacFileCacheLockEnter(pCache);
1063
1064	/* Cleanup deleting all cache entries waiting for in progress entries to finish. */
1065	pdmacFileCacheDestroyList(&pCache->LruRecentlyUsedIn);
1066	pdmacFileCacheDestroyList(&pCache->LruRecentlyUsedOut);
1067	pdmacFileCacheDestroyList(&pCache->LruFrequentlyUsed);
1068
1069	pdmacFileCacheLockLeave(pCache);
1070
1071	RTCritSectDelete(&pCache->CritSect);
1072	}
1073
1074	/**
1075	* Initializes per endpoint cache data
1076	* like the AVL tree used to access cached entries.
1077	*
1078	* @returns VBox status code.
1079	* @param pEndpoint The endpoint to init the cache for,
1080	* @param pClassFile The global class data for file endpoints.
1081	*/
1082	int pdmacFileEpCacheInit(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint, PPDMASYNCCOMPLETIONEPCLASSFILE pClassFile)
1083	{
1084	PPDMACFILEENDPOINTCACHE pEndpointCache = &pEndpoint->DataCache;
1085
1086	pEndpointCache->pCache = &pClassFile->Cache;
1087	RTListInit(&pEndpointCache->ListDirtyNotCommitted);
1088	int rc = RTSpinlockCreate(&pEndpointCache->LockList);
1089
1090	if (RT_SUCCESS(rc))
1091	{
1092	rc = RTSemRWCreate(&pEndpointCache->SemRWEntries);
1093	if (RT_SUCCESS(rc))
1094	{
1095	pEndpointCache->pTree = (PAVLRFOFFTREE)RTMemAllocZ(sizeof(AVLRFOFFTREE));
1096	if (pEndpointCache->pTree)
1097	{
1098	pClassFile->Cache.cRefs++;
1099	RTListAppend(&pClassFile->Cache.ListEndpoints, &pEndpointCache->NodeCacheEndpoint);
1100
1101	/* Arm the timer if this is the first endpoint. */
1102	if ( pClassFile->Cache.cRefs == 1
1103	&& pClassFile->Cache.u32CommitTimeoutMs > 0)
1104	rc = TMTimerSetMillies(pClassFile->Cache.pTimerCommit, pClassFile->Cache.u32CommitTimeoutMs);
1105	}
1106	else
1107	rc = VERR_NO_MEMORY;
1108
1109	if (RT_FAILURE(rc))
1110	RTSemRWDestroy(pEndpointCache->SemRWEntries);
1111	}
1112
1113	if (RT_FAILURE(rc))
1114	RTSpinlockDestroy(pEndpointCache->LockList);
1115	}
1116
1117	#ifdef VBOX_WITH_STATISTICS
1118	if (RT_SUCCESS(rc))
1119	{
1120	STAMR3RegisterF(pClassFile->Core.pVM, &pEndpointCache->StatWriteDeferred,
1121	STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS,
1122	STAMUNIT_COUNT, "Number of deferred writes",
1123	"/PDM/AsyncCompletion/File/%s/Cache/DeferredWrites", RTPathFilename(pEndpoint->Core.pszUri));
1124	}
1125	#endif
1126
1127	LogFlowFunc(("Leave rc=%Rrc\n", rc));
1128	return rc;
1129	}
1130
1131	/**
1132	* Callback for the AVL destroy routine. Frees a cache entry for this endpoint.
1133	*
1134	* @returns IPRT status code.
1135	* @param pNode The node to destroy.
1136	* @param pvUser Opaque user data.
1137	*/
1138	static int pdmacFileEpCacheEntryDestroy(PAVLRFOFFNODECORE pNode, void *pvUser)
1139	{
1140	PPDMACFILECACHEENTRY pEntry = (PPDMACFILECACHEENTRY)pNode;
1141	PPDMACFILECACHEGLOBAL pCache = (PPDMACFILECACHEGLOBAL)pvUser;
1142	PPDMACFILEENDPOINTCACHE pEndpointCache = &pEntry->pEndpoint->DataCache;
1143
1144	while (ASMAtomicReadU32(&pEntry->fFlags) & (PDMACFILECACHE_ENTRY_IO_IN_PROGRESS \| PDMACFILECACHE_ENTRY_IS_DIRTY))
1145	{
1146	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
1147	RTThreadSleep(250);
1148	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1149	}
1150
1151	AssertMsg(!(pEntry->fFlags & (PDMACFILECACHE_ENTRY_IO_IN_PROGRESS \| PDMACFILECACHE_ENTRY_IS_DIRTY)),
1152	("Entry is dirty and/or still in progress fFlags=%#x\n", pEntry->fFlags));
1153
1154	bool fUpdateCache = pEntry->pList == &pCache->LruFrequentlyUsed
1155	\|\| pEntry->pList == &pCache->LruRecentlyUsedIn;
1156
1157	pdmacFileCacheEntryRemoveFromList(pEntry);
1158
1159	if (fUpdateCache)
1160	pdmacFileCacheSub(pCache, pEntry->cbData);
1161
1162	RTMemPageFree(pEntry->pbData, pEntry->cbData);
1163	RTMemFree(pEntry);
1164
1165	return VINF_SUCCESS;
1166	}
1167
1168	/**
1169	* Destroys all cache ressources used by the given endpoint.
1170	*
1171	* @returns nothing.
1172	* @param pEndpoint The endpoint to the destroy.
1173	*/
1174	void pdmacFileEpCacheDestroy(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint)
1175	{
1176	PPDMACFILEENDPOINTCACHE pEndpointCache = &pEndpoint->DataCache;
1177	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1178
1179	/* Make sure nobody is accessing the cache while we delete the tree. */
1180	pdmacFileCacheLockEnter(pCache);
1181	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1182	RTAvlrFileOffsetDestroy(pEndpointCache->pTree, pdmacFileEpCacheEntryDestroy, pCache);
1183	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
1184
1185	RTSpinlockDestroy(pEndpointCache->LockList);
1186
1187	pCache->cRefs--;
1188	RTListNodeRemove(&pEndpointCache->NodeCacheEndpoint);
1189
1190	if ( !pCache->cRefs
1191	&& pCache->u32CommitTimeoutMs > 0)
1192	TMTimerStop(pCache->pTimerCommit);
1193
1194	pdmacFileCacheLockLeave(pCache);
1195
1196	RTSemRWDestroy(pEndpointCache->SemRWEntries);
1197
1198	#ifdef VBOX_WITH_STATISTICS
1199	PPDMASYNCCOMPLETIONEPCLASSFILE pEpClassFile = (PPDMASYNCCOMPLETIONEPCLASSFILE)pEndpoint->Core.pEpClass;
1200
1201	STAMR3Deregister(pEpClassFile->Core.pVM, &pEndpointCache->StatWriteDeferred);
1202	#endif
1203	}
1204
1205	static PPDMACFILECACHEENTRY pdmacFileEpCacheGetCacheEntryByOffset(PPDMACFILEENDPOINTCACHE pEndpointCache, RTFOFF off)
1206	{
1207	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1208	PPDMACFILECACHEENTRY pEntry = NULL;
1209
1210	STAM_PROFILE_ADV_START(&pCache->StatTreeGet, Cache);
1211
1212	RTSemRWRequestRead(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1213	pEntry = (PPDMACFILECACHEENTRY)RTAvlrFileOffsetRangeGet(pEndpointCache->pTree, off);
1214	if (pEntry)
1215	pdmacFileEpCacheEntryRef(pEntry);
1216	RTSemRWReleaseRead(pEndpointCache->SemRWEntries);
1217
1218	STAM_PROFILE_ADV_STOP(&pCache->StatTreeGet, Cache);
1219
1220	return pEntry;
1221	}
1222
1223	/**
1224	* Return the best fit cache entries for the given offset.
1225	*
1226	* @returns nothing.
1227	* @param pEndpointCache The endpoint cache.
1228	* @param off The offset.
1229	* @param pEntryAbove Where to store the pointer to the best fit entry above the
1230	* the given offset. NULL if not required.
1231	* @param pEntryBelow Where to store the pointer to the best fit entry below the
1232	* the given offset. NULL if not required.
1233	*/
1234	static void pdmacFileEpCacheGetCacheBestFitEntryByOffset(PPDMACFILEENDPOINTCACHE pEndpointCache, RTFOFF off,
1235	PPDMACFILECACHEENTRY *ppEntryAbove,
1236	PPDMACFILECACHEENTRY *ppEntryBelow)
1237	{
1238	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1239
1240	STAM_PROFILE_ADV_START(&pCache->StatTreeGet, Cache);
1241
1242	RTSemRWRequestRead(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1243	if (ppEntryAbove)
1244	{
1245	ppEntryAbove = (PPDMACFILECACHEENTRY)RTAvlrFileOffsetGetBestFit(pEndpointCache->pTree, off, true /fAbove*/);
1246	if (*ppEntryAbove)
1247	pdmacFileEpCacheEntryRef(*ppEntryAbove);
1248	}
1249
1250	if (ppEntryBelow)
1251	{
1252	ppEntryBelow = (PPDMACFILECACHEENTRY)RTAvlrFileOffsetGetBestFit(pEndpointCache->pTree, off, false /fAbove*/);
1253	if (*ppEntryBelow)
1254	pdmacFileEpCacheEntryRef(*ppEntryBelow);
1255	}
1256	RTSemRWReleaseRead(pEndpointCache->SemRWEntries);
1257
1258	STAM_PROFILE_ADV_STOP(&pCache->StatTreeGet, Cache);
1259	}
1260
1261	static void pdmacFileEpCacheInsertEntry(PPDMACFILEENDPOINTCACHE pEndpointCache, PPDMACFILECACHEENTRY pEntry)
1262	{
1263	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1264
1265	STAM_PROFILE_ADV_START(&pCache->StatTreeInsert, Cache);
1266	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1267	bool fInserted = RTAvlrFileOffsetInsert(pEndpointCache->pTree, &pEntry->Core);
1268	AssertMsg(fInserted, ("Node was not inserted into tree\n"));
1269	STAM_PROFILE_ADV_STOP(&pCache->StatTreeInsert, Cache);
1270	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
1271	}
1272
1273	/**
1274	* Allocates and initializes a new entry for the cache.
1275	* The entry has a reference count of 1.
1276	*
1277	* @returns Pointer to the new cache entry or NULL if out of memory.
1278	* @param pCache The cache the entry belongs to.
1279	* @param pEndoint The endpoint the entry holds data for.
1280	* @param off Start offset.
1281	* @param cbData Size of the cache entry.
1282	* @param pbBuffer Pointer to the buffer to use.
1283	* NULL if a new buffer should be allocated.
1284	* The buffer needs to have the same size of the entry.
1285	*/
1286	static PPDMACFILECACHEENTRY pdmacFileCacheEntryAlloc(PPDMACFILECACHEGLOBAL pCache,
1287	PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint,
1288	RTFOFF off, size_t cbData, uint8_t *pbBuffer)
1289	{
1290	PPDMACFILECACHEENTRY pEntryNew = (PPDMACFILECACHEENTRY)RTMemAllocZ(sizeof(PDMACFILECACHEENTRY));
1291
1292	if (RT_UNLIKELY(!pEntryNew))
1293	return NULL;
1294
1295	pEntryNew->Core.Key = off;
1296	pEntryNew->Core.KeyLast = off + cbData - 1;
1297	pEntryNew->pEndpoint = pEndpoint;
1298	pEntryNew->pCache = pCache;
1299	pEntryNew->fFlags = 0;
1300	pEntryNew->cRefs = 1; /* We are using it now. */
1301	pEntryNew->pList = NULL;
1302	pEntryNew->cbData = cbData;
1303	pEntryNew->pWaitingHead = NULL;
1304	pEntryNew->pWaitingTail = NULL;
1305	if (pbBuffer)
1306	pEntryNew->pbData = pbBuffer;
1307	else
1308	pEntryNew->pbData = (uint8_t *)RTMemPageAlloc(cbData);
1309
1310	if (RT_UNLIKELY(!pEntryNew->pbData))
1311	{
1312	RTMemFree(pEntryNew);
1313	return NULL;
1314	}
1315
1316	return pEntryNew;
1317	}
1318
1319	/**
1320	* Adds a segment to the waiting list for a cache entry
1321	* which is currently in progress.
1322	*
1323	* @returns nothing.
1324	* @param pEntry The cache entry to add the segment to.
1325	* @param pSeg The segment to add.
1326	*/
1327	DECLINLINE(void) pdmacFileEpCacheEntryAddWaitingSegment(PPDMACFILECACHEENTRY pEntry, PPDMACFILETASKSEG pSeg)
1328	{
1329	pSeg->pNext = NULL;
1330
1331	if (pEntry->pWaitingHead)
1332	{
1333	AssertPtr(pEntry->pWaitingTail);
1334
1335	pEntry->pWaitingTail->pNext = pSeg;
1336	pEntry->pWaitingTail = pSeg;
1337	}
1338	else
1339	{
1340	Assert(!pEntry->pWaitingTail);
1341
1342	pEntry->pWaitingHead = pSeg;
1343	pEntry->pWaitingTail = pSeg;
1344	}
1345	}
1346
1347	/**
1348	* Checks that a set of flags is set/clear acquiring the R/W semaphore
1349	* in exclusive mode.
1350	*
1351	* @returns true if the flag in fSet is set and the one in fClear is clear.
1352	* false othwerise.
1353	* The R/W semaphore is only held if true is returned.
1354	*
1355	* @param pEndpointCache The endpoint cache instance data.
1356	* @param pEntry The entry to check the flags for.
1357	* @param fSet The flag which is tested to be set.
1358	* @param fClear The flag which is tested to be clear.
1359	*/
1360	DECLINLINE(bool) pdmacFileEpCacheEntryFlagIsSetClearAcquireLock(PPDMACFILEENDPOINTCACHE pEndpointCache,
1361	PPDMACFILECACHEENTRY pEntry,
1362	uint32_t fSet, uint32_t fClear)
1363	{
1364	uint32_t fFlags = ASMAtomicReadU32(&pEntry->fFlags);
1365	bool fPassed = ((fFlags & fSet) && !(fFlags & fClear));
1366
1367	if (fPassed)
1368	{
1369	/* Acquire the lock and check again becuase the completion callback might have raced us. */
1370	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1371
1372	fFlags = ASMAtomicReadU32(&pEntry->fFlags);
1373	fPassed = ((fFlags & fSet) && !(fFlags & fClear));
1374
1375	/* Drop the lock if we didn't passed the test. */
1376	if (!fPassed)
1377	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
1378	}
1379
1380	return fPassed;
1381	}
1382
1383	/**
1384	* Copies data to a buffer described by a I/O memory context.
1385	*
1386	* @returns nothing.
1387	* @param pIoMemCtx The I/O memory context to copy the data into.
1388	* @param pbData Pointer to the data data to copy.
1389	* @param cbData Amount of data to copy.
1390	*/
1391	static void pdmacFileEpCacheCopyToIoMemCtx(PPDMIOMEMCTX pIoMemCtx,
1392	uint8_t *pbData,
1393	size_t cbData)
1394	{
1395	while (cbData)
1396	{
1397	size_t cbCopy = cbData;
1398	uint8_t *pbBuf = pdmIoMemCtxGetBuffer(pIoMemCtx, &cbCopy);
1399
1400	AssertPtr(pbBuf);
1401
1402	memcpy(pbBuf, pbData, cbCopy);
1403
1404	cbData -= cbCopy;
1405	pbData += cbCopy;
1406	}
1407	}
1408
1409	/**
1410	* Copies data from a buffer described by a I/O memory context.
1411	*
1412	* @returns nothing.
1413	* @param pIoMemCtx The I/O memory context to copy the data from.
1414	* @param pbData Pointer to the destination buffer.
1415	* @param cbData Amount of data to copy.
1416	*/
1417	static void pdmacFileEpCacheCopyFromIoMemCtx(PPDMIOMEMCTX pIoMemCtx,
1418	uint8_t *pbData,
1419	size_t cbData)
1420	{
1421	while (cbData)
1422	{
1423	size_t cbCopy = cbData;
1424	uint8_t *pbBuf = pdmIoMemCtxGetBuffer(pIoMemCtx, &cbCopy);
1425
1426	AssertPtr(pbBuf);
1427
1428	memcpy(pbData, pbBuf, cbCopy);
1429
1430	cbData -= cbCopy;
1431	pbData += cbCopy;
1432	}
1433	}
1434
1435	/**
1436	* Add a buffer described by the I/O memory context
1437	* to the entry waiting for completion.
1438	*
1439	* @returns nothing.
1440	* @param pEntry The entry to add the buffer to.
1441	* @param pTask Task associated with the buffer.
1442	* @param pIoMemCtx The memory context to use.
1443	* @param OffDiff Offset from the start of the buffer
1444	* in the entry.
1445	* @param cbData Amount of data to wait for onthis entry.
1446	* @param fWrite Flag whether the task waits because it wants to write
1447	* to the cache entry.
1448	*/
1449	static void pdmacFileEpCacheEntryWaitersAdd(PPDMACFILECACHEENTRY pEntry,
1450	PPDMASYNCCOMPLETIONTASKFILE pTask,
1451	PPDMIOMEMCTX pIoMemCtx,
1452	RTFOFF OffDiff,
1453	size_t cbData,
1454	bool fWrite)
1455	{
1456	while (cbData)
1457	{
1458	PPDMACFILETASKSEG pSeg = (PPDMACFILETASKSEG)RTMemAllocZ(sizeof(PDMACFILETASKSEG));
1459	size_t cbSeg = cbData;
1460	uint8_t *pbBuf = pdmIoMemCtxGetBuffer(pIoMemCtx, &cbSeg);
1461
1462	pSeg->pTask = pTask;
1463	pSeg->uBufOffset = OffDiff;
1464	pSeg->cbTransfer = cbSeg;
1465	pSeg->pvBuf = pbBuf;
1466	pSeg->fWrite = fWrite;
1467
1468	pdmacFileEpCacheEntryAddWaitingSegment(pEntry, pSeg);
1469
1470	cbData -= cbSeg;
1471	OffDiff += cbSeg;
1472	}
1473	}
1474
1475	/**
1476	* Passthrough a part of a request directly to the I/O manager
1477	* handling the endpoint.
1478	*
1479	* @returns nothing.
1480	* @param pEndpoint The endpoint.
1481	* @param pTask The task.
1482	* @param pIoMemCtx The I/O memory context to use.
1483	* @param offStart Offset to start transfer from.
1484	* @param cbData Amount of data to transfer.
1485	* @param enmTransferType The transfer type (read/write)
1486	*/
1487	static void pdmacFileEpCacheRequestPassthrough(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint,
1488	PPDMASYNCCOMPLETIONTASKFILE pTask,
1489	PPDMIOMEMCTX pIoMemCtx,
1490	RTFOFF offStart, size_t cbData,
1491	PDMACTASKFILETRANSFER enmTransferType)
1492	{
1493	while (cbData)
1494	{
1495	size_t cbSeg = cbData;
1496	uint8_t *pbBuf = pdmIoMemCtxGetBuffer(pIoMemCtx, &cbSeg);
1497	PPDMACTASKFILE pIoTask = pdmacFileTaskAlloc(pEndpoint);
1498	AssertPtr(pIoTask);
1499
1500	pIoTask->pEndpoint = pEndpoint;
1501	pIoTask->enmTransferType = enmTransferType;
1502	pIoTask->Off = offStart;
1503	pIoTask->DataSeg.cbSeg = cbSeg;
1504	pIoTask->DataSeg.pvSeg = pbBuf;
1505	pIoTask->pvUser = pTask;
1506	pIoTask->pfnCompleted = pdmacFileEpTaskCompleted;
1507
1508	offStart += cbSeg;
1509	cbData -= cbSeg;
1510
1511	/* Send it off to the I/O manager. */
1512	pdmacFileEpAddTask(pEndpoint, pIoTask);
1513	}
1514	}
1515
1516	/**
1517	* Calculate aligned offset and size for a new cache entry
1518	* which do not intersect with an already existing entry and the
1519	* file end.
1520	*
1521	* @returns The number of bytes the entry can hold of the requested amount
1522	* of byte.
1523	* @param pEndpoint The endpoint.
1524	* @param pEndpointCache The endpoint cache.
1525	* @param off The start offset.
1526	* @param cb The number of bytes the entry needs to hold at least.
1527	* @param uAlignment Alignment of the boundary sizes.
1528	* @param poffAligned Where to store the aligned offset.
1529	* @param pcbAligned Where to store the aligned size of the entry.
1530	*/
1531	static size_t pdmacFileEpCacheEntryBoundariesCalc(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint,
1532	PPDMACFILEENDPOINTCACHE pEndpointCache,
1533	RTFOFF off, size_t cb,
1534	unsigned uAlignment,
1535	RTFOFF poffAligned, size_t pcbAligned)
1536	{
1537	size_t cbAligned;
1538	size_t cbInEntry = 0;
1539	RTFOFF offAligned;
1540	PPDMACFILECACHEENTRY pEntryAbove = NULL;
1541	PPDMACFILECACHEENTRY pEntryBelow = NULL;
1542
1543	/* Get the best fit entries around the offset */
1544	pdmacFileEpCacheGetCacheBestFitEntryByOffset(pEndpointCache, off,
1545	&pEntryAbove, &pEntryBelow);
1546
1547	/* Log the info */
1548	LogFlow(("%sest fit entry below off=%RTfoff (BestFit=%RTfoff BestFitEnd=%RTfoff BestFitSize=%u)\n",
1549	pEntryBelow ? "B" : "No b",
1550	off,
1551	pEntryBelow ? pEntryBelow->Core.Key : 0,
1552	pEntryBelow ? pEntryBelow->Core.KeyLast : 0,
1553	pEntryBelow ? pEntryBelow->cbData : 0));
1554
1555	LogFlow(("%sest fit entry above off=%RTfoff (BestFit=%RTfoff BestFitEnd=%RTfoff BestFitSize=%u)\n",
1556	pEntryAbove ? "B" : "No b",
1557	off,
1558	pEntryAbove ? pEntryAbove->Core.Key : 0,
1559	pEntryAbove ? pEntryAbove->Core.KeyLast : 0,
1560	pEntryAbove ? pEntryAbove->cbData : 0));
1561
1562	/* Align the offset first. */
1563	offAligned = off & ~(RTFOFF)(512-1);
1564	if ( pEntryBelow
1565	&& offAligned <= pEntryBelow->Core.KeyLast)
1566	offAligned = pEntryBelow->Core.KeyLast;
1567
1568	if ( pEntryAbove
1569	&& off + (RTFOFF)cb > pEntryAbove->Core.Key)
1570	{
1571	cbInEntry = pEntryAbove->Core.Key - off;
1572	cbAligned = pEntryAbove->Core.Key - offAligned;
1573	}
1574	else
1575	{
1576	/*
1577	* Align the size to a 4KB boundary.
1578	* Memory size is aligned to a page boundary
1579	* and memory is wasted if the size is rather small.
1580	* (For example reads with a size of 512 bytes).
1581	*/
1582	cbInEntry = cb;
1583	cbAligned = RT_ALIGN_Z(cb + (off - offAligned), uAlignment);
1584
1585	/*
1586	* Clip to file size if the original request doesn't
1587	* exceed the file (not an appending write)
1588	*/
1589	uint64_t cbReq = off + (RTFOFF)cb;
1590	if (cbReq >= pEndpoint->cbFile)
1591	cbAligned = cbReq - offAligned;
1592	else
1593	cbAligned = RT_MIN(pEndpoint->cbFile - offAligned, cbAligned);
1594	if (pEntryAbove)
1595	{
1596	Assert(pEntryAbove->Core.Key >= off);
1597	cbAligned = RT_MIN(cbAligned, (uint64_t)pEntryAbove->Core.Key - offAligned);
1598	}
1599	}
1600
1601	/* A few sanity checks */
1602	AssertMsg(!pEntryBelow \|\| pEntryBelow->Core.KeyLast < offAligned,
1603	("Aligned start offset intersects with another cache entry\n"));
1604	AssertMsg(!pEntryAbove \|\| (offAligned + (RTFOFF)cbAligned) <= pEntryAbove->Core.Key,
1605	("Aligned size intersects with another cache entry\n"));
1606	Assert(cbInEntry <= cbAligned);
1607	AssertMsg( ( offAligned + (RTFOFF)cbAligned <= (RTFOFF)pEndpoint->cbFile
1608	&& off + (RTFOFF)cb <= (RTFOFF)pEndpoint->cbFile)
1609	\|\| (offAligned + (RTFOFF)cbAligned <= off + (RTFOFF)cb),
1610	("Unwanted file size increase\n"));
1611
1612	if (pEntryBelow)
1613	pdmacFileEpCacheEntryRelease(pEntryBelow);
1614	if (pEntryAbove)
1615	pdmacFileEpCacheEntryRelease(pEntryAbove);
1616
1617	LogFlow(("offAligned=%RTfoff cbAligned=%u\n", offAligned, cbAligned));
1618
1619	*poffAligned = offAligned;
1620	*pcbAligned = cbAligned;
1621
1622	return cbInEntry;
1623	}
1624
1625	/**
1626	* Create a new cache entry evicting data from the cache if required.
1627	*
1628	* @returns Pointer to the new cache entry or NULL
1629	* if not enough bytes could be evicted from the cache.
1630	* @param pEndpoint The endpoint.
1631	* @param pEndpointCache The endpoint cache.
1632	* @param off The offset.
1633	* @param cb Number of bytes the cache entry should have.
1634	* @param uAlignment Alignment the size of the entry should have.
1635	* @param pcbData Where to store the number of bytes the new
1636	* entry can hold. May be lower than actually requested
1637	* due to another entry intersecting the access range.
1638	*/
1639	static PPDMACFILECACHEENTRY pdmacFileEpCacheEntryCreate(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint,
1640	PPDMACFILEENDPOINTCACHE pEndpointCache,
1641	RTFOFF off, size_t cb,
1642	unsigned uAlignment,
1643	size_t *pcbData)
1644	{
1645	RTFOFF offStart = 0;
1646	size_t cbEntry = 0;
1647	PPDMACFILECACHEENTRY pEntryNew = NULL;
1648	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1649	uint8_t *pbBuffer = NULL;
1650
1651	*pcbData = pdmacFileEpCacheEntryBoundariesCalc(pEndpoint,
1652	pEndpointCache,
1653	off, cb,
1654	uAlignment,
1655	&offStart, &cbEntry);
1656
1657	pdmacFileCacheLockEnter(pCache);
1658	bool fEnough = pdmacFileCacheReclaim(pCache, cbEntry, true, &pbBuffer);
1659
1660	if (fEnough)
1661	{
1662	LogFlow(("Evicted enough bytes (%u requested). Creating new cache entry\n", cbEntry));
1663
1664	pEntryNew = pdmacFileCacheEntryAlloc(pCache, pEndpoint,
1665	offStart, cbEntry,
1666	pbBuffer);
1667	if (RT_LIKELY(pEntryNew))
1668	{
1669	pdmacFileCacheEntryAddToList(&pCache->LruRecentlyUsedIn, pEntryNew);
1670	pdmacFileCacheAdd(pCache, cbEntry);
1671	pdmacFileCacheLockLeave(pCache);
1672
1673	pdmacFileEpCacheInsertEntry(pEndpointCache, pEntryNew);
1674
1675	AssertMsg( (off >= pEntryNew->Core.Key)
1676	&& (off + (RTFOFF)*pcbData <= pEntryNew->Core.KeyLast + 1),
1677	("Overflow in calculation off=%RTfoff OffsetAligned=%RTfoff\n",
1678	off, pEntryNew->Core.Key));
1679	}
1680	else
1681	pdmacFileCacheLockLeave(pCache);
1682	}
1683	else
1684	pdmacFileCacheLockLeave(pCache);
1685
1686	return pEntryNew;
1687	}
1688
1689	/**
1690	* Reads the specified data from the endpoint using the cache if possible.
1691	*
1692	* @returns VBox status code.
1693	* @param pEndpoint The endpoint to read from.
1694	* @param pTask The task structure used as identifier for this request.
1695	* @param off The offset to start reading from.
1696	* @param paSegments Pointer to the array holding the destination buffers.
1697	* @param cSegments Number of segments in the array.
1698	* @param cbRead Number of bytes to read.
1699	*/
1700	int pdmacFileEpCacheRead(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint, PPDMASYNCCOMPLETIONTASKFILE pTask,
1701	RTFOFF off, PCRTSGSEG paSegments, size_t cSegments,
1702	size_t cbRead)
1703	{
1704	int rc = VINF_SUCCESS;
1705	PPDMACFILEENDPOINTCACHE pEndpointCache = &pEndpoint->DataCache;
1706	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1707	PPDMACFILECACHEENTRY pEntry;
1708
1709	LogFlowFunc((": pEndpoint=%#p{%s} pTask=%#p off=%RTfoff paSegments=%#p cSegments=%u cbRead=%u\n",
1710	pEndpoint, pEndpoint->Core.pszUri, pTask, off, paSegments, cSegments, cbRead));
1711
1712	/* Set to completed to make sure that the task is valid while we access it. */
1713	ASMAtomicWriteBool(&pTask->fCompleted, true);
1714
1715	/* Init the I/O memory context */
1716	PDMIOMEMCTX IoMemCtx;
1717	pdmIoMemCtxInit(&IoMemCtx, paSegments, cSegments);
1718
1719	while (cbRead)
1720	{
1721	size_t cbToRead;
1722
1723	pEntry = pdmacFileEpCacheGetCacheEntryByOffset(pEndpointCache, off);
1724
1725	/*
1726	* If there is no entry we try to create a new one eviciting unused pages
1727	* if the cache is full. If this is not possible we will pass the request through
1728	* and skip the caching (all entries may be still in progress so they can't
1729	* be evicted)
1730	* If we have an entry it can be in one of the LRU lists where the entry
1731	* contains data (recently used or frequently used LRU) so we can just read
1732	* the data we need and put the entry at the head of the frequently used LRU list.
1733	* In case the entry is in one of the ghost lists it doesn't contain any data.
1734	* We have to fetch it again evicting pages from either T1 or T2 to make room.
1735	*/
1736	if (pEntry)
1737	{
1738	RTFOFF OffDiff = off - pEntry->Core.Key;
1739
1740	AssertMsg(off >= pEntry->Core.Key,
1741	("Overflow in calculation off=%RTfoff OffsetAligned=%RTfoff\n",
1742	off, pEntry->Core.Key));
1743
1744	AssertPtr(pEntry->pList);
1745
1746	cbToRead = RT_MIN(pEntry->cbData - OffDiff, cbRead);
1747
1748	AssertMsg(off + (RTFOFF)cbToRead <= pEntry->Core.Key + pEntry->Core.KeyLast + 1,
1749	("Buffer of cache entry exceeded off=%RTfoff cbToRead=%d\n",
1750	off, cbToRead));
1751
1752	cbRead -= cbToRead;
1753
1754	if (!cbRead)
1755	STAM_COUNTER_INC(&pCache->cHits);
1756	else
1757	STAM_COUNTER_INC(&pCache->cPartialHits);
1758
1759	STAM_COUNTER_ADD(&pCache->StatRead, cbToRead);
1760
1761	/* Ghost lists contain no data. */
1762	if ( (pEntry->pList == &pCache->LruRecentlyUsedIn)
1763	\|\| (pEntry->pList == &pCache->LruFrequentlyUsed))
1764	{
1765	if (pdmacFileEpCacheEntryFlagIsSetClearAcquireLock(pEndpointCache, pEntry,
1766	PDMACFILECACHE_ENTRY_IO_IN_PROGRESS,
1767	PDMACFILECACHE_ENTRY_IS_DIRTY))
1768	{
1769	/* Entry didn't completed yet. Append to the list */
1770	pdmacFileEpCacheEntryWaitersAdd(pEntry, pTask,
1771	&IoMemCtx,
1772	OffDiff, cbToRead,
1773	false /* fWrite */);
1774	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
1775	}
1776	else
1777	{
1778	/* Read as much as we can from the entry. */
1779	pdmacFileEpCacheCopyToIoMemCtx(&IoMemCtx, pEntry->pbData + OffDiff, cbToRead);
1780	ASMAtomicSubS32(&pTask->cbTransferLeft, cbToRead);
1781	}
1782
1783	/* Move this entry to the top position */
1784	if (pEntry->pList == &pCache->LruFrequentlyUsed)
1785	{
1786	pdmacFileCacheLockEnter(pCache);
1787	pdmacFileCacheEntryAddToList(&pCache->LruFrequentlyUsed, pEntry);
1788	pdmacFileCacheLockLeave(pCache);
1789	}
1790	/* Release the entry */
1791	pdmacFileEpCacheEntryRelease(pEntry);
1792	}
1793	else
1794	{
1795	uint8_t *pbBuffer = NULL;
1796
1797	LogFlow(("Fetching data for ghost entry %#p from file\n", pEntry));
1798
1799	pdmacFileCacheLockEnter(pCache);
1800	pdmacFileCacheEntryRemoveFromList(pEntry); /* Remove it before we remove data, otherwise it may get freed when evicting data. */
1801	bool fEnough = pdmacFileCacheReclaim(pCache, pEntry->cbData, true, &pbBuffer);
1802
1803	/* Move the entry to Am and fetch it to the cache. */
1804	if (fEnough)
1805	{
1806	pdmacFileCacheEntryAddToList(&pCache->LruFrequentlyUsed, pEntry);
1807	pdmacFileCacheAdd(pCache, pEntry->cbData);
1808	pdmacFileCacheLockLeave(pCache);
1809
1810	if (pbBuffer)
1811	pEntry->pbData = pbBuffer;
1812	else
1813	pEntry->pbData = (uint8_t *)RTMemPageAlloc(pEntry->cbData);
1814	AssertPtr(pEntry->pbData);
1815
1816	pdmacFileEpCacheEntryWaitersAdd(pEntry, pTask,
1817	&IoMemCtx,
1818	OffDiff, cbToRead,
1819	false /* fWrite */);
1820	pdmacFileCacheReadFromEndpoint(pEntry);
1821	/* Release the entry */
1822	pdmacFileEpCacheEntryRelease(pEntry);
1823	}
1824	else
1825	{
1826	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
1827	STAM_PROFILE_ADV_START(&pCache->StatTreeRemove, Cache);
1828	RTAvlrFileOffsetRemove(pEndpointCache->pTree, pEntry->Core.Key);
1829	STAM_PROFILE_ADV_STOP(&pCache->StatTreeRemove, Cache);
1830	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
1831
1832	pdmacFileCacheLockLeave(pCache);
1833
1834	RTMemFree(pEntry);
1835
1836	pdmacFileEpCacheRequestPassthrough(pEndpoint, pTask,
1837	&IoMemCtx, off, cbToRead,
1838	PDMACTASKFILETRANSFER_READ);
1839	}
1840	}
1841	}
1842	else
1843	{
1844	#ifdef VBOX_WITH_IO_READ_CACHE
1845	/* No entry found for this offset. Create a new entry and fetch the data to the cache. */
1846	PPDMACFILECACHEENTRY pEntryNew = pdmacFileEpCacheEntryCreate(pEndpoint,
1847	pEndpointCache,
1848	off, cbRead,
1849	PAGE_SIZE,
1850	&cbToRead);
1851
1852	cbRead -= cbToRead;
1853
1854	if (pEntryNew)
1855	{
1856	if (!cbRead)
1857	STAM_COUNTER_INC(&pCache->cMisses);
1858	else
1859	STAM_COUNTER_INC(&pCache->cPartialHits);
1860
1861	pdmacFileEpCacheEntryWaitersAdd(pEntryNew, pTask,
1862	&IoMemCtx,
1863	off - pEntryNew->Core.Key,
1864	cbToRead,
1865	false /* fWrite */);
1866	pdmacFileCacheReadFromEndpoint(pEntryNew);
1867	pdmacFileEpCacheEntryRelease(pEntryNew); /* it is protected by the I/O in progress flag now. */
1868	}
1869	else
1870	{
1871	/*
1872	* There is not enough free space in the cache.
1873	* Pass the request directly to the I/O manager.
1874	*/
1875	LogFlow(("Couldn't evict %u bytes from the cache. Remaining request will be passed through\n", cbToRead));
1876
1877	pdmacFileEpCacheRequestPassthrough(pEndpoint, pTask,
1878	&IoMemCtx, off, cbToRead,
1879	PDMACTASKFILETRANSFER_READ);
1880	}
1881	#else
1882	/* Clip read size if neccessary. */
1883	PPDMACFILECACHEENTRY pEntryAbove;
1884	pdmacFileEpCacheGetCacheBestFitEntryByOffset(pEndpointCache, off,
1885	&pEntryAbove, NULL);
1886
1887	if (pEntryAbove)
1888	{
1889	if (off + (RTFOFF)cbRead > pEntryAbove->Core.Key)
1890	cbToRead = pEntryAbove->Core.Key - off;
1891	else
1892	cbToRead = cbRead;
1893
1894	pdmacFileEpCacheEntryRelease(pEntryAbove);
1895	}
1896	else
1897	cbToRead = cbRead;
1898
1899	cbRead -= cbToRead;
1900	pdmacFileEpCacheRequestPassthrough(pEndpoint, pTask,
1901	&IoMemCtx, off, cbToRead,
1902	PDMACTASKFILETRANSFER_READ);
1903	#endif
1904	}
1905	off += cbToRead;
1906	}
1907
1908	ASMAtomicWriteBool(&pTask->fCompleted, false);
1909
1910	if (ASMAtomicReadS32(&pTask->cbTransferLeft) == 0
1911	&& !ASMAtomicXchgBool(&pTask->fCompleted, true))
1912	pdmR3AsyncCompletionCompleteTask(&pTask->Core, VINF_SUCCESS, false);
1913	else
1914	rc = VINF_AIO_TASK_PENDING;
1915
1916	LogFlowFunc((": Leave rc=%Rrc\n", rc));
1917
1918	return rc;
1919	}
1920
1921	/**
1922	* Writes the given data to the endpoint using the cache if possible.
1923	*
1924	* @returns VBox status code.
1925	* @param pEndpoint The endpoint to write to.
1926	* @param pTask The task structure used as identifier for this request.
1927	* @param off The offset to start writing to
1928	* @param paSegments Pointer to the array holding the source buffers.
1929	* @param cSegments Number of segments in the array.
1930	* @param cbWrite Number of bytes to write.
1931	*/
1932	int pdmacFileEpCacheWrite(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint, PPDMASYNCCOMPLETIONTASKFILE pTask,
1933	RTFOFF off, PCRTSGSEG paSegments, size_t cSegments,
1934	size_t cbWrite)
1935	{
1936	int rc = VINF_SUCCESS;
1937	PPDMACFILEENDPOINTCACHE pEndpointCache = &pEndpoint->DataCache;
1938	PPDMACFILECACHEGLOBAL pCache = pEndpointCache->pCache;
1939	PPDMACFILECACHEENTRY pEntry;
1940
1941	LogFlowFunc((": pEndpoint=%#p{%s} pTask=%#p off=%RTfoff paSegments=%#p cSegments=%u cbWrite=%u\n",
1942	pEndpoint, pEndpoint->Core.pszUri, pTask, off, paSegments, cSegments, cbWrite));
1943
1944	/* Set to completed to make sure that the task is valid while we access it. */
1945	ASMAtomicWriteBool(&pTask->fCompleted, true);
1946
1947	/* Init the I/O memory context */
1948	PDMIOMEMCTX IoMemCtx;
1949	pdmIoMemCtxInit(&IoMemCtx, paSegments, cSegments);
1950
1951	while (cbWrite)
1952	{
1953	size_t cbToWrite;
1954
1955	pEntry = pdmacFileEpCacheGetCacheEntryByOffset(pEndpointCache, off);
1956
1957	if (pEntry)
1958	{
1959	/* Write the data into the entry and mark it as dirty */
1960	AssertPtr(pEntry->pList);
1961
1962	RTFOFF OffDiff = off - pEntry->Core.Key;
1963
1964	AssertMsg(off >= pEntry->Core.Key,
1965	("Overflow in calculation off=%RTfoff OffsetAligned=%RTfoff\n",
1966	off, pEntry->Core.Key));
1967
1968	cbToWrite = RT_MIN(pEntry->cbData - OffDiff, cbWrite);
1969	cbWrite -= cbToWrite;
1970
1971	if (!cbWrite)
1972	STAM_COUNTER_INC(&pCache->cHits);
1973	else
1974	STAM_COUNTER_INC(&pCache->cPartialHits);
1975
1976	STAM_COUNTER_ADD(&pCache->StatWritten, cbToWrite);
1977
1978	/* Ghost lists contain no data. */
1979	if ( (pEntry->pList == &pCache->LruRecentlyUsedIn)
1980	\|\| (pEntry->pList == &pCache->LruFrequentlyUsed))
1981	{
1982	/* Check if the entry is dirty. */
1983	if(pdmacFileEpCacheEntryFlagIsSetClearAcquireLock(pEndpointCache, pEntry,
1984	PDMACFILECACHE_ENTRY_IS_DIRTY,
1985	0))
1986	{
1987	/* If it is dirty but not in progrss just update the data. */
1988	if (!(pEntry->fFlags & PDMACFILECACHE_ENTRY_IO_IN_PROGRESS))
1989	{
1990	pdmacFileEpCacheCopyFromIoMemCtx(&IoMemCtx,
1991	pEntry->pbData + OffDiff,
1992	cbToWrite);
1993	ASMAtomicSubS32(&pTask->cbTransferLeft, cbToWrite);
1994	}
1995	else
1996	{
1997	/* The data isn't written to the file yet */
1998	pdmacFileEpCacheEntryWaitersAdd(pEntry, pTask,
1999	&IoMemCtx,
2000	OffDiff, cbToWrite,
2001	true /* fWrite */);
2002	STAM_COUNTER_INC(&pEndpointCache->StatWriteDeferred);
2003	}
2004
2005	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
2006	}
2007	else /* Dirty bit not set */
2008	{
2009	/*
2010	* Check if a read is in progress for this entry.
2011	* We have to defer processing in that case.
2012	*/
2013	if(pdmacFileEpCacheEntryFlagIsSetClearAcquireLock(pEndpointCache, pEntry,
2014	PDMACFILECACHE_ENTRY_IO_IN_PROGRESS,
2015	0))
2016	{
2017	pdmacFileEpCacheEntryWaitersAdd(pEntry, pTask,
2018	&IoMemCtx,
2019	OffDiff, cbToWrite,
2020	true /* fWrite */);
2021	STAM_COUNTER_INC(&pEndpointCache->StatWriteDeferred);
2022	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
2023	}
2024	else /* I/O in progress flag not set */
2025	{
2026	/* Write as much as we can into the entry and update the file. */
2027	pdmacFileEpCacheCopyFromIoMemCtx(&IoMemCtx,
2028	pEntry->pbData + OffDiff,
2029	cbToWrite);
2030	ASMAtomicSubS32(&pTask->cbTransferLeft, cbToWrite);
2031
2032	bool fCommit = pdmacFileCacheAddDirtyEntry(pEndpointCache, pEntry);
2033	if (fCommit)
2034	pdmacFileCacheCommitDirtyEntries(pCache);
2035	}
2036	} /* Dirty bit not set */
2037
2038	/* Move this entry to the top position */
2039	if (pEntry->pList == &pCache->LruFrequentlyUsed)
2040	{
2041	pdmacFileCacheLockEnter(pCache);
2042	pdmacFileCacheEntryAddToList(&pCache->LruFrequentlyUsed, pEntry);
2043	pdmacFileCacheLockLeave(pCache);
2044	}
2045
2046	pdmacFileEpCacheEntryRelease(pEntry);
2047	}
2048	else /* Entry is on the ghost list */
2049	{
2050	uint8_t *pbBuffer = NULL;
2051
2052	pdmacFileCacheLockEnter(pCache);
2053	pdmacFileCacheEntryRemoveFromList(pEntry); /* Remove it before we remove data, otherwise it may get freed when evicting data. */
2054	bool fEnough = pdmacFileCacheReclaim(pCache, pEntry->cbData, true, &pbBuffer);
2055
2056	if (fEnough)
2057	{
2058	/* Move the entry to Am and fetch it to the cache. */
2059	pdmacFileCacheEntryAddToList(&pCache->LruFrequentlyUsed, pEntry);
2060	pdmacFileCacheAdd(pCache, pEntry->cbData);
2061	pdmacFileCacheLockLeave(pCache);
2062
2063	if (pbBuffer)
2064	pEntry->pbData = pbBuffer;
2065	else
2066	pEntry->pbData = (uint8_t *)RTMemPageAlloc(pEntry->cbData);
2067	AssertPtr(pEntry->pbData);
2068
2069	pdmacFileEpCacheEntryWaitersAdd(pEntry, pTask,
2070	&IoMemCtx,
2071	OffDiff, cbToWrite,
2072	true /* fWrite */);
2073	STAM_COUNTER_INC(&pEndpointCache->StatWriteDeferred);
2074	pdmacFileCacheReadFromEndpoint(pEntry);
2075
2076	/* Release the reference. If it is still needed the I/O in progress flag should protect it now. */
2077	pdmacFileEpCacheEntryRelease(pEntry);
2078	}
2079	else
2080	{
2081	RTSemRWRequestWrite(pEndpointCache->SemRWEntries, RT_INDEFINITE_WAIT);
2082	STAM_PROFILE_ADV_START(&pCache->StatTreeRemove, Cache);
2083	RTAvlrFileOffsetRemove(pEndpointCache->pTree, pEntry->Core.Key);
2084	STAM_PROFILE_ADV_STOP(&pCache->StatTreeRemove, Cache);
2085	RTSemRWReleaseWrite(pEndpointCache->SemRWEntries);
2086
2087	pdmacFileCacheLockLeave(pCache);
2088
2089	RTMemFree(pEntry);
2090	pdmacFileEpCacheRequestPassthrough(pEndpoint, pTask,
2091	&IoMemCtx, off, cbToWrite,
2092	PDMACTASKFILETRANSFER_WRITE);
2093	}
2094	}
2095	}
2096	else /* No entry found */
2097	{
2098	/*
2099	* No entry found. Try to create a new cache entry to store the data in and if that fails
2100	* write directly to the file.
2101	*/
2102	PPDMACFILECACHEENTRY pEntryNew = pdmacFileEpCacheEntryCreate(pEndpoint,
2103	pEndpointCache,
2104	off, cbWrite,
2105	512,
2106	&cbToWrite);
2107
2108	cbWrite -= cbToWrite;
2109
2110	if (pEntryNew)
2111	{
2112	RTFOFF offDiff = off - pEntryNew->Core.Key;
2113
2114	STAM_COUNTER_INC(&pCache->cHits);
2115
2116	/*
2117	* Check if it is possible to just write the data without waiting
2118	* for it to get fetched first.
2119	*/
2120	if (!offDiff && pEntryNew->cbData == cbToWrite)
2121	{
2122	pdmacFileEpCacheCopyFromIoMemCtx(&IoMemCtx,
2123	pEntryNew->pbData,
2124	cbToWrite);
2125	ASMAtomicSubS32(&pTask->cbTransferLeft, cbToWrite);
2126
2127	bool fCommit = pdmacFileCacheAddDirtyEntry(pEndpointCache, pEntryNew);
2128	if (fCommit)
2129	pdmacFileCacheCommitDirtyEntries(pCache);
2130	STAM_COUNTER_ADD(&pCache->StatWritten, cbToWrite);
2131	}
2132	else
2133	{
2134	/* Defer the write and fetch the data from the endpoint. */
2135	pdmacFileEpCacheEntryWaitersAdd(pEntryNew, pTask,
2136	&IoMemCtx,
2137	offDiff, cbToWrite,
2138	true /* fWrite */);
2139	STAM_COUNTER_INC(&pEndpointCache->StatWriteDeferred);
2140	pdmacFileCacheReadFromEndpoint(pEntryNew);
2141	}
2142
2143	pdmacFileEpCacheEntryRelease(pEntryNew);
2144	}
2145	else
2146	{
2147	/*
2148	* There is not enough free space in the cache.
2149	* Pass the request directly to the I/O manager.
2150	*/
2151	LogFlow(("Couldn't evict %u bytes from the cache. Remaining request will be passed through\n", cbToWrite));
2152
2153	STAM_COUNTER_INC(&pCache->cMisses);
2154
2155	pdmacFileEpCacheRequestPassthrough(pEndpoint, pTask,
2156	&IoMemCtx, off, cbToWrite,
2157	PDMACTASKFILETRANSFER_WRITE);
2158	}
2159	}
2160
2161	off += cbToWrite;
2162	}
2163
2164	ASMAtomicWriteBool(&pTask->fCompleted, false);
2165
2166	if (ASMAtomicReadS32(&pTask->cbTransferLeft) == 0
2167	&& !ASMAtomicXchgBool(&pTask->fCompleted, true))
2168	pdmR3AsyncCompletionCompleteTask(&pTask->Core, VINF_SUCCESS, false);
2169	else
2170	rc = VINF_AIO_TASK_PENDING;
2171
2172	LogFlowFunc((": Leave rc=%Rrc\n", rc));
2173
2174	return rc;
2175	}
2176
2177	int pdmacFileEpCacheFlush(PPDMASYNCCOMPLETIONENDPOINTFILE pEndpoint, PPDMASYNCCOMPLETIONTASKFILE pTask)
2178	{
2179	int rc = VINF_SUCCESS;
2180
2181	LogFlowFunc((": pEndpoint=%#p{%s} pTask=%#p\n",
2182	pEndpoint, pEndpoint->Core.pszUri, pTask));
2183
2184	/* Commit dirty entries in the cache. */
2185	pdmacFileCacheEndpointCommit(&pEndpoint->DataCache);
2186
2187	LogFlowFunc((": Leave rc=%Rrc\n", rc));
2188	return rc;
2189	}
2190

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source: vbox/trunk/src/VBox/VMM/PDMAsyncCompletionFileCache.cpp@ 29561

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