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[NTOSKRNL] Add wait support in CcCanIWrite()

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This commit is contained in:
Pierre Schweitzer 2018-02-07 21:09:36 +01:00
parent 92e64a6c9b
commit c11e947f61
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GPG Key ID: 7545556C3D585B0B
2 changed files with 66 additions and 3 deletions
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68
ntoskrnl/cc/copy.c
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@ -446,6 +446,8 @@ CcCanIWrite (
IN BOOLEAN Wait,
IN BOOLEAN Retrying)
{
KEVENT WaitEvent;
DEFERRED_WRITE Context;
PFSRTL_COMMON_FCB_HEADER Fcb;
PROS_SHARED_CACHE_MAP SharedCacheMap;
@ -455,7 +457,8 @@ CcCanIWrite (
/* We cannot write if dirty pages count is above threshold */
if (CcTotalDirtyPages > CcDirtyPageThreshold)
{
return FALSE;
/* Can the caller wait till it's possible to write? */
goto CanIWait;
}
/* We cannot write if dirty pages count will bring use above
@ -463,7 +466,8 @@ CcCanIWrite (
*/
if (CcTotalDirtyPages + (BytesToWrite / PAGE_SIZE) > CcDirtyPageThreshold)
{
return FALSE;
/* Can the caller wait till it's possible to write? */
goto CanIWait;
}
/* Is there a limit per file object? */
@ -479,17 +483,75 @@ CcCanIWrite (
/* Is dirty page count above local threshold? */
if (SharedCacheMap->DirtyPages > SharedCacheMap->DirtyPageThreshold)
{
return FALSE;
/* Can the caller wait till it's possible to write? */
goto CanIWait;
}
/* We cannot write if dirty pages count will bring use above
* XXX: Might not be accurate
*/
if (SharedCacheMap->DirtyPages + (BytesToWrite / PAGE_SIZE) > SharedCacheMap->DirtyPageThreshold)
{
/* Can the caller wait till it's possible to write? */
goto CanIWait;
}
return TRUE;
CanIWait:
/* If we reached that point, it means caller cannot write
* If he cannot wait, then fail and deny write
*/
if (!Wait)
{
return FALSE;
}
/* Otherwise, if there are no deferred writes yet, start the lazy writer */
if (IsListEmpty(&CcDeferredWrites))
{
KIRQL OldIrql;
OldIrql = KeAcquireQueuedSpinLock(LockQueueMasterLock);
CcScheduleLazyWriteScan(TRUE);
KeReleaseQueuedSpinLock(LockQueueMasterLock, OldIrql);
}
/* Initialize our wait event */
KeInitializeEvent(&WaitEvent, NotificationEvent, FALSE);
/* And prepare a dummy context */
Context.NodeTypeCode = NODE_TYPE_DEFERRED_WRITE;
Context.NodeByteSize = sizeof(DEFERRED_WRITE);
Context.FileObject = FileObject;
Context.BytesToWrite = BytesToWrite;
Context.LimitModifiedPages = BooleanFlagOn(Fcb->Flags, FSRTL_FLAG_LIMIT_MODIFIED_PAGES);
Context.Event = &WaitEvent;
/* And queue it */
if (Retrying)
{
/* To the top, if that's a retry */
ExInterlockedInsertHeadList(&CcDeferredWrites,
&Context.DeferredWriteLinks,
&CcDeferredWriteSpinLock);
}
else
{
/* To the bottom, if that's a first time */
ExInterlockedInsertTailList(&CcDeferredWrites,
&Context.DeferredWriteLinks,
&CcDeferredWriteSpinLock);
}
/* Now, we'll loop until our event is set. When it is set, it means that caller
* can immediately write, and has to
*/
do
{
CcPostDeferredWrites();
} while (KeWaitForSingleObject(&WaitEvent, Executive, KernelMode, FALSE, &CcIdleDelay) != STATUS_SUCCESS);
return TRUE;
}

1
ntoskrnl/include/internal/cc.h
View File

@ -50,6 +50,7 @@ extern LIST_ENTRY CcIdleWorkerThreadList;
extern LIST_ENTRY CcRegularWorkQueue;
extern LIST_ENTRY CcPostTickWorkQueue;
extern NPAGED_LOOKASIDE_LIST CcTwilightLookasideList;
extern LARGE_INTEGER CcIdleDelay;
typedef struct _PF_SCENARIO_ID
{