mdlsup.c File Reference

#include "cc.h"

Go to the source code of this file.

Defines
#define	me   (0x00000010)
Functions
VOID	CcMdlRead (IN PFILE_OBJECT FileObject, IN PLARGE_INTEGER FileOffset, IN ULONG Length, OUT PMDL *MdlChain, OUT PIO_STATUS_BLOCK IoStatus)
VOID	CcMdlReadComplete (IN PFILE_OBJECT FileObject, IN PMDL MdlChain)
VOID	CcMdlReadComplete2 (IN PFILE_OBJECT FileObject, IN PMDL MdlChain)
VOID	CcPrepareMdlWrite (IN PFILE_OBJECT FileObject, IN PLARGE_INTEGER FileOffset, IN ULONG Length, OUT PMDL *MdlChain, OUT PIO_STATUS_BLOCK IoStatus)
VOID	CcMdlWriteComplete (IN PFILE_OBJECT FileObject, IN PLARGE_INTEGER FileOffset, IN PMDL MdlChain)
VOID	CcMdlWriteComplete2 (IN PFILE_OBJECT FileObject, IN PLARGE_INTEGER FileOffset, IN PMDL MdlChain)

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Define Documentation

#define me   (0x00000010)

Definition at line 27 of file mdlsup.c.

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Function Documentation

VOID CcMdlRead (  IN PFILE_OBJECT  FileObject, IN PLARGE_INTEGER  FileOffset, IN ULONG  Length, OUT PMDL *  MdlChain, OUT PIO_STATUS_BLOCK  IoStatus )

Definition at line 30 of file mdlsup.c. References ASSERT, _PRIVATE_CACHE_MAP::BeyondLastByte1, _PRIVATE_CACHE_MAP::BeyondLastByte2, CcFreeActiveVacb(), CcFreeVirtualAddress(), CcGetVirtualAddress(), CcMdlReadWait, CcMdlReadWaitMiss, CcMissCounter, CcScheduleReadAhead(), CcThrowAway, COMPUTE_PAGES_SPANNED, DebugTrace, DebugTrace2, ExRaiseStatus(), FALSE, _PRIVATE_CACHE_MAP::FileOffset1, _PRIVATE_CACHE_MAP::FileOffset2, _SHARED_CACHE_MAP::FileSize, FlagOn, FO_RANDOM_ACCESS, GetActiveVacb, IoAllocateMdl(), IoFreeMdl(), IoReadAccess, KernelMode, me, mm, MmProbeAndLockPages(), MmResetPageFaultReadAhead, MmSavePageFaultReadAhead, MmSetPageFaultReadAhead, MmUnlockPages(), _SHARED_CACHE_MAP::NeedToZero, _MDL::Next, NULL, PsGetCurrentThread, _PRIVATE_CACHE_MAP::ReadAheadEnabled, _PRIVATE_CACHE_MAP::ReadAheadLength, and TRUE. Referenced by FsRtlMdlReadDev(), and UdfCommonRead(). : This routine attempts to lock the specified file data in the cache and return a description of it in an Mdl along with the correct I/O status. It is *not* safe to call this routine from Dpc level. This routine is synchronous, and raises on errors. As each call returns, the pages described by the Mdl are locked in memory, but not mapped in system space. If the caller needs the pages mapped in system space, then it must map them. Note that each call is a "single shot" which should be followed by a call to CcMdlReadComplete. To resume an Mdl-based transfer, the caller must form one or more subsequent calls to CcMdlRead with appropriately adjusted parameters. Arguments: FileObject - Pointer to the file object for a file which was opened with NO_INTERMEDIATE_BUFFERING clear, i.e., for which CcInitializeCacheMap was called by the file system. FileOffset - Byte offset in file for desired data. Length - Length of desired data in bytes. MdlChain - On output it returns a pointer to an Mdl chain describing the desired data. Note that even if FALSE is returned, one or more Mdls may have been allocated, as may be ascertained by the IoStatus.Information field (see below). IoStatus - Pointer to standard I/O status block to receive the status for the transfer. (STATUS_SUCCESS guaranteed for cache hits, otherwise the actual I/O status is returned.) The I/O Information Field indicates how many bytes have been successfully locked down in the Mdl Chain. Return Value: None Raises: STATUS_INSUFFICIENT_RESOURCES - If a pool allocation failure occurs. --*/ { PSHARED_CACHE_MAP SharedCacheMap; PPRIVATE_CACHE_MAP PrivateCacheMap; PVOID CacheBuffer; LARGE_INTEGER FOffset; PMDL Mdl = NULL; PMDL MdlTemp; PETHREAD Thread = PsGetCurrentThread(); ULONG SavedState = 0; ULONG OriginalLength = Length; ULONG Information = 0; PVACB Vacb = NULL; ULONG SavedMissCounter = 0; KIRQL OldIrql; ULONG ActivePage; ULONG PageIsDirty; PVACB ActiveVacb = NULL; DebugTrace(+1, me, "CcMdlRead\n", 0 ); DebugTrace( 0, me, " FileObject = %08lx\n", FileObject ); DebugTrace2(0, me, " FileOffset = %08lx, %08lx\n", FileOffset->LowPart, FileOffset->HighPart ); DebugTrace( 0, me, " Length = %08lx\n", Length ); // // Save the current readahead hints. // MmSavePageFaultReadAhead( Thread, &SavedState ); // // Get pointer to SharedCacheMap. // SharedCacheMap = FileObject->SectionObjectPointer->SharedCacheMap; PrivateCacheMap = FileObject->PrivateCacheMap; // // See if we have an active Vacb, that we need to free. // GetActiveVacb( SharedCacheMap, OldIrql, ActiveVacb, ActivePage, PageIsDirty ); // // If there is an end of a page to be zeroed, then free that page now, // so we don't send Greg the uninitialized data... // if ((ActiveVacb != NULL) || (SharedCacheMap->NeedToZero != NULL)) { CcFreeActiveVacb( SharedCacheMap, ActiveVacb, ActivePage, PageIsDirty ); } // // If read ahead is enabled, then do the read ahead here so it // overlaps with the copy (otherwise we will do it below). // Note that we are assuming that we will not get ahead of our // current transfer - if read ahead is working it should either // already be in memory or else underway. // if (PrivateCacheMap->ReadAheadEnabled && (PrivateCacheMap->ReadAheadLength[1] == 0)) { CcScheduleReadAhead( FileObject, FileOffset, Length ); } // // Increment performance counters // CcMdlReadWait += 1; // // This is not an exact solution, but when IoPageRead gets a miss, // it cannot tell whether it was CcCopyRead or CcMdlRead, but since // the miss should occur very soon, by loading the pointer here // probably the right counter will get incremented, and in any case, // we hope the errrors average out! // CcMissCounter = &CcMdlReadWaitMiss; FOffset = *FileOffset; // // Check for read past file size, the caller must filter this case out. // ASSERT( ( FOffset.QuadPart + (LONGLONG)Length ) <= SharedCacheMap->FileSize.QuadPart ); // // Put try-finally around the loop to deal with any exceptions // try { // // Not all of the transfer will come back at once, so we have to loop // until the entire transfer is complete. // while (Length != 0) { ULONG ReceivedLength; LARGE_INTEGER BeyondLastByte; // // Map the data and read it in (if necessary) with the // MmProbeAndLockPages call below. // CacheBuffer = CcGetVirtualAddress( SharedCacheMap, FOffset, &Vacb, &ReceivedLength ); if (ReceivedLength > Length) { ReceivedLength = Length; } BeyondLastByte.QuadPart = FOffset.QuadPart + (LONGLONG)ReceivedLength; // // Now attempt to allocate an Mdl to describe the mapped data. // DebugTrace( 0, mm, "IoAllocateMdl:\n", 0 ); DebugTrace( 0, mm, " BaseAddress = %08lx\n", CacheBuffer ); DebugTrace( 0, mm, " Length = %08lx\n", ReceivedLength ); Mdl = IoAllocateMdl( CacheBuffer, ReceivedLength, FALSE, FALSE, NULL ); DebugTrace( 0, mm, " <Mdl = %08lx\n", Mdl ); if (Mdl == NULL) { DebugTrace( 0, 0, "Failed to allocate Mdl\n", 0 ); ExRaiseStatus( STATUS_INSUFFICIENT_RESOURCES ); } DebugTrace( 0, mm, "MmProbeAndLockPages:\n", 0 ); DebugTrace( 0, mm, " Mdl = %08lx\n", Mdl ); // // Set to see if the miss counter changes in order to // detect when we should turn on read ahead. // SavedMissCounter += CcMdlReadWaitMiss; MmSetPageFaultReadAhead( Thread, COMPUTE_PAGES_SPANNED( CacheBuffer, ReceivedLength ) - 1); MmProbeAndLockPages( Mdl, KernelMode, IoReadAccess ); SavedMissCounter -= CcMdlReadWaitMiss; // // Unmap the data now, now that the pages are locked down. // CcFreeVirtualAddress( Vacb ); Vacb = NULL; // // Now link the Mdl into the caller's chain // if ( *MdlChain == NULL ) { *MdlChain = Mdl; } else { MdlTemp = CONTAINING_RECORD( *MdlChain, MDL, Next ); while (MdlTemp->Next != NULL) { MdlTemp = MdlTemp->Next; } MdlTemp->Next = Mdl; } Mdl = NULL; // // Assume we did not get all the data we wanted, and set FOffset // to the end of the returned data. // FOffset = BeyondLastByte; // // Update number of bytes transferred. // Information += ReceivedLength; // // Calculate length left to transfer. // Length -= ReceivedLength; } } finally { CcMissCounter = &CcThrowAway; // // Restore the readahead hints. // MmResetPageFaultReadAhead( Thread, SavedState ); if (AbnormalTermination()) { // // We may have failed to allocate an Mdl while still having // data mapped. // if (Vacb != NULL) { CcFreeVirtualAddress( Vacb ); } if (Mdl != NULL) { IoFreeMdl( Mdl ); } // // Otherwise loop to deallocate the Mdls // while (*MdlChain != NULL) { MdlTemp = (*MdlChain)->Next; DebugTrace( 0, mm, "MmUnlockPages/IoFreeMdl:\n", 0 ); DebugTrace( 0, mm, " Mdl = %08lx\n", *MdlChain ); MmUnlockPages( *MdlChain ); IoFreeMdl( *MdlChain ); *MdlChain = MdlTemp; } DebugTrace(-1, me, "CcMdlRead -> Unwinding\n", 0 ); } else { // // Now enable read ahead if it looks like we got any misses, and do // the first one. // if (!FlagOn( FileObject->Flags, FO_RANDOM_ACCESS ) && !PrivateCacheMap->ReadAheadEnabled && (SavedMissCounter != 0)) { PrivateCacheMap->ReadAheadEnabled = TRUE; CcScheduleReadAhead( FileObject, FileOffset, OriginalLength ); } // // Now that we have described our desired read ahead, let's // shift the read history down. // PrivateCacheMap->FileOffset1 = PrivateCacheMap->FileOffset2; PrivateCacheMap->BeyondLastByte1 = PrivateCacheMap->BeyondLastByte2; PrivateCacheMap->FileOffset2 = *FileOffset; PrivateCacheMap->BeyondLastByte2.QuadPart = FileOffset->QuadPart + (LONGLONG)OriginalLength; IoStatus->Status = STATUS_SUCCESS; IoStatus->Information = Information; } } DebugTrace( 0, me, " <MdlChain = %08lx\n", *MdlChain ); DebugTrace2(0, me, " <IoStatus = %08lx, %08lx\n", IoStatus->Status, IoStatus->Information ); DebugTrace(-1, me, "CcMdlRead -> VOID\n", 0 ); return; }

VOID CcMdlReadComplete (  IN PFILE_OBJECT  FileObject, IN PMDL  MdlChain )

Definition at line 381 of file mdlsup.c. References CcMdlReadComplete2(), _DEVICE_OBJECT::DriverObject, _DRIVER_OBJECT::FastIoDispatch, IoGetRelatedDeviceObject(), _FAST_IO_DISPATCH::MdlReadComplete, NULL, and _FAST_IO_DISPATCH::SizeOfFastIoDispatch. Referenced by UdfCompleteMdl(). { PDEVICE_OBJECT DeviceObject; PFAST_IO_DISPATCH FastIoDispatch; DeviceObject = IoGetRelatedDeviceObject( FileObject ); FastIoDispatch = DeviceObject->DriverObject->FastIoDispatch; if ((FastIoDispatch != NULL) && (FastIoDispatch->SizeOfFastIoDispatch > FIELD_OFFSET(FAST_IO_DISPATCH, MdlWriteComplete)) && (FastIoDispatch->MdlReadComplete != NULL) && FastIoDispatch->MdlReadComplete( FileObject, MdlChain, DeviceObject )) { NOTHING; } else { CcMdlReadComplete2( FileObject, MdlChain ); } }

VOID CcMdlReadComplete2 (  IN PFILE_OBJECT  FileObject, IN PMDL  MdlChain )

Definition at line 406 of file mdlsup.c. References DebugTrace, IoFreeMdl(), me, mm, MmUnlockPages(), _MDL::Next, and NULL. Referenced by CcMdlReadComplete(), and FsRtlMdlReadCompleteDev(). : This routine must be called at IPL0 after a call to CcMdlRead. The caller must simply supply the address of the MdlChain returned in CcMdlRead. This call does the following: Deletes the MdlChain Arguments: FileObject - Pointer to the file object for a file which was opened with NO_INTERMEDIATE_BUFFERING clear, i.e., for which CcInitializeCacheMap was called by the file system. MdlChain - same as returned from corresponding call to CcMdlRead. Return Value: None. --*/ { PMDL MdlNext; DebugTrace(+1, me, "CcMdlReadComplete\n", 0 ); DebugTrace( 0, me, " FileObject = %08lx\n", FileObject ); DebugTrace( 0, me, " MdlChain = %08lx\n", MdlChain ); // // Deallocate the Mdls // while (MdlChain != NULL) { MdlNext = MdlChain->Next; DebugTrace( 0, mm, "MmUnlockPages/IoFreeMdl:\n", 0 ); DebugTrace( 0, mm, " Mdl = %08lx\n", MdlChain ); MmUnlockPages( MdlChain ); IoFreeMdl( MdlChain ); MdlChain = MdlNext; } DebugTrace(-1, me, "CcMdlReadComplete -> VOID\n", 0 ); }

VOID CcMdlWriteComplete (  IN PFILE_OBJECT  FileObject, IN PLARGE_INTEGER  FileOffset, IN PMDL  MdlChain )

Definition at line 812 of file mdlsup.c. References CcMdlWriteComplete2(), _DEVICE_OBJECT::DriverObject, _DRIVER_OBJECT::FastIoDispatch, IoGetRelatedDeviceObject(), _FAST_IO_DISPATCH::MdlWriteComplete, NULL, and _FAST_IO_DISPATCH::SizeOfFastIoDispatch. { PDEVICE_OBJECT DeviceObject; PFAST_IO_DISPATCH FastIoDispatch; DeviceObject = IoGetRelatedDeviceObject( FileObject ); FastIoDispatch = DeviceObject->DriverObject->FastIoDispatch; if ((FastIoDispatch != NULL) && (FastIoDispatch->SizeOfFastIoDispatch > FIELD_OFFSET(FAST_IO_DISPATCH, MdlWriteComplete)) && (FastIoDispatch->MdlWriteComplete != NULL) && FastIoDispatch->MdlWriteComplete( FileObject, FileOffset, MdlChain, DeviceObject )) { NOTHING; } else { CcMdlWriteComplete2( FileObject, FileOffset, MdlChain ); } }

VOID CcMdlWriteComplete2 (  IN PFILE_OBJECT  FileObject, IN PLARGE_INTEGER  FileOffset, IN PMDL  MdlChain )

Definition at line 838 of file mdlsup.c. References CcAcquireMasterLock, CcDecrementOpenCount, CcDirtySharedCacheMapList, CcReleaseMasterLock, CcScheduleLazyWriteScan(), CcSetDirtyInMask(), DebugTrace, _SHARED_CACHE_MAP::DirtyPages, FlagOn, _SHARED_CACHE_MAP::Flags, FO_WRITE_THROUGH, FsRtlNormalizeNtstatus(), IoFreeMdl(), LazyWriter, me, mm, MmFlushSection(), MmUnlockPages(), _MDL::Next, NT_SUCCESS, NTSTATUS(), NULL, _SHARED_CACHE_MAP::OpenCount, _LAZY_WRITER::OtherWork, _LAZY_WRITER::ScanActive, _SHARED_CACHE_MAP::SharedCacheMapLinks, _SHARED_CACHE_MAP_LIST_CURSOR::SharedCacheMapLinks, TRUE, and WRITE_QUEUED. Referenced by CcMdlWriteComplete(), and FsRtlMdlWriteCompleteDev(). : This routine must be called at IPL0 after a call to CcPrepareMdlWrite. The caller supplies the ActualLength of data that it actually wrote into the buffer, which may be less than or equal to the Length specified in CcPrepareMdlWrite. This call does the following: Makes sure the data up to ActualLength eventually gets written. If WriteThrough is FALSE, the data will not be written immediately. If WriteThrough is TRUE, then the data is written synchronously. Unmaps the pages (if mapped), unlocks them and deletes the MdlChain Arguments: FileObject - Pointer to the file object for a file which was opened with NO_INTERMEDIATE_BUFFERING clear, i.e., for which CcInitializeCacheMap was called by the file system. FileOffset - Original file offset read above. MdlChain - same as returned from corresponding call to CcPrepareMdlWrite. Return Value: None --*/ { PMDL MdlNext; PSHARED_CACHE_MAP SharedCacheMap; LARGE_INTEGER FOffset; IO_STATUS_BLOCK IoStatus; KIRQL OldIrql; NTSTATUS StatusToRaise = STATUS_SUCCESS; DebugTrace(+1, me, "CcMdlWriteComplete\n", 0 ); DebugTrace( 0, me, " FileObject = %08lx\n", FileObject ); DebugTrace( 0, me, " MdlChain = %08lx\n", MdlChain ); SharedCacheMap = FileObject->SectionObjectPointer->SharedCacheMap; // // Deallocate the Mdls // FOffset.QuadPart = *(LONGLONG UNALIGNED *)FileOffset; while (MdlChain != NULL) { MdlNext = MdlChain->Next; DebugTrace( 0, mm, "MmUnlockPages/IoFreeMdl:\n", 0 ); DebugTrace( 0, mm, " Mdl = %08lx\n", MdlChain ); // // Now clear the dirty bits in the Pte and set them in the // Pfn. // MmUnlockPages( MdlChain ); // // Extract the File Offset for this part of the transfer. // if (FlagOn(FileObject->Flags, FO_WRITE_THROUGH)) { MmFlushSection ( FileObject->SectionObjectPointer, &FOffset, MdlChain->ByteCount, &IoStatus, TRUE ); // // If we got an I/O error, remember it. // if (!NT_SUCCESS(IoStatus.Status)) { StatusToRaise = IoStatus.Status; } } else { // // Ignore the only exception (allocation error), and console // ourselves for having tried. // CcSetDirtyInMask( SharedCacheMap, &FOffset, MdlChain->ByteCount ); } FOffset.QuadPart = FOffset.QuadPart + (LONGLONG)(MdlChain->ByteCount); IoFreeMdl( MdlChain ); MdlChain = MdlNext; } // // Now release our open count. // CcAcquireMasterLock( &OldIrql ); CcDecrementOpenCount( SharedCacheMap, 'ldmC' ); if ((SharedCacheMap->OpenCount == 0) && !FlagOn(SharedCacheMap->Flags, WRITE_QUEUED) && (SharedCacheMap->DirtyPages == 0)) { // // Move to the dirty list. // RemoveEntryList( &SharedCacheMap->SharedCacheMapLinks ); InsertTailList( &CcDirtySharedCacheMapList.SharedCacheMapLinks, &SharedCacheMap->SharedCacheMapLinks ); // // Make sure the Lazy Writer will wake up, because we // want him to delete this SharedCacheMap. // LazyWriter.OtherWork = TRUE; if (!LazyWriter.ScanActive) { CcScheduleLazyWriteScan(); } } CcReleaseMasterLock( OldIrql ); // // If we got an I/O error, raise it now. // if (!NT_SUCCESS(StatusToRaise)) { FsRtlNormalizeNtstatus( StatusToRaise, STATUS_UNEXPECTED_IO_ERROR ); } DebugTrace(-1, me, "CcMdlWriteComplete -> TRUE\n", 0 ); return; }

VOID CcPrepareMdlWrite (  IN PFILE_OBJECT  FileObject, IN PLARGE_INTEGER  FileOffset, IN ULONG  Length, OUT PMDL *  MdlChain, OUT PIO_STATUS_BLOCK  IoStatus )

Definition at line 466 of file mdlsup.c. References _SHARED_CACHE_MAP::BcbSpinLock, CcAcquireMasterLock, CcFreeActiveVacb(), CcFreeVirtualAddress(), CcGetVirtualAddress(), CcIncrementOpenCount, CcMapAndRead(), CcReleaseMasterLock, CcSetDirtyInMask(), DebugTrace, DebugTrace2, ExRaiseStatus(), FALSE, GetActiveVacb, IoAllocateMdl(), IoFreeMdl(), IoWriteAccess, KernelMode, me, mm, MmDisablePageFaultClustering, MmEnablePageFaultClustering, MmProbeAndLockPages(), MmUnlockPages(), _SHARED_CACHE_MAP::NeedToZero, _MDL::Next, NULL, PAGE_SIZE, TRUE, _SHARED_CACHE_MAP::ValidDataGoal, VOID(), ZERO_FIRST_PAGE, ZERO_LAST_PAGE, and ZERO_MIDDLE_PAGES. Referenced by FsRtlPrepareMdlWriteDev(). : This routine attempts to lock the specified file data in the cache and return a description of it in an Mdl along with the correct I/O status. Pages to be completely overwritten may be satisfied with emtpy pages. It is *not* safe to call this routine from Dpc level. This call is synchronous and raises on error. When this call returns, the caller may immediately begin to transfer data into the buffers via the Mdl. When the call returns with TRUE, the pages described by the Mdl are locked in memory, but not mapped in system space. If the caller needs the pages mapped in system space, then it must map them. On the subsequent call to CcMdlWriteComplete the pages will be unmapped if they were mapped, and in any case unlocked and the Mdl deallocated. Arguments: FileObject - Pointer to the file object for a file which was opened with NO_INTERMEDIATE_BUFFERING clear, i.e., for which CcInitializeCacheMap was called by the file system. FileOffset - Byte offset in file for desired data. Length - Length of desired data in bytes. MdlChain - On output it returns a pointer to an Mdl chain describing the desired data. Note that even if FALSE is returned, one or more Mdls may have been allocated, as may be ascertained by the IoStatus.Information field (see below). IoStatus - Pointer to standard I/O status block to receive the status for the in-transfer of the data. (STATUS_SUCCESS guaranteed for cache hits, otherwise the actual I/O status is returned.) The I/O Information Field indicates how many bytes have been successfully locked down in the Mdl Chain. Return Value: None --*/ { PSHARED_CACHE_MAP SharedCacheMap; PVOID CacheBuffer; LARGE_INTEGER FOffset; PMDL Mdl = NULL; PMDL MdlTemp; LARGE_INTEGER Temp; ULONG SavedState = 0; ULONG ZeroFlags = 0; ULONG Information = 0; KIRQL OldIrql; ULONG ActivePage; ULONG PageIsDirty; PVACB Vacb = NULL; DebugTrace(+1, me, "CcPrepareMdlWrite\n", 0 ); DebugTrace( 0, me, " FileObject = %08lx\n", FileObject ); DebugTrace2(0, me, " FileOffset = %08lx, %08lx\n", FileOffset->LowPart, FileOffset->HighPart ); DebugTrace( 0, me, " Length = %08lx\n", Length ); // // Get pointer to SharedCacheMap. // SharedCacheMap = FileObject->SectionObjectPointer->SharedCacheMap; // // See if we have an active Vacb, that we need to free. // GetActiveVacb( SharedCacheMap, OldIrql, Vacb, ActivePage, PageIsDirty ); // // If there is an end of a page to be zeroed, then free that page now, // so it does not cause our data to get zeroed. If there is an active // page, free it so we have the correct ValidDataGoal. // if ((Vacb != NULL) || (SharedCacheMap->NeedToZero != NULL)) { CcFreeActiveVacb( SharedCacheMap, Vacb, ActivePage, PageIsDirty ); Vacb = NULL; } FOffset = *FileOffset; // // Put try-finally around the loop to deal with exceptions // try { // // Not all of the transfer will come back at once, so we have to loop // until the entire transfer is complete. // while (Length != 0) { ULONG ReceivedLength; LARGE_INTEGER BeyondLastByte; // // Map and see how much we could potentially access at this // FileOffset, then cut it down if it is more than we need. // CacheBuffer = CcGetVirtualAddress( SharedCacheMap, FOffset, &Vacb, &ReceivedLength ); if (ReceivedLength > Length) { ReceivedLength = Length; } BeyondLastByte.QuadPart = FOffset.QuadPart + (LONGLONG)ReceivedLength; // // At this point we can calculate the ZeroFlags. // // // We can always zero middle pages, if any. // ZeroFlags = ZERO_MIDDLE_PAGES; // // See if we are completely overwriting the first or last page. // if (((FOffset.LowPart & (PAGE_SIZE - 1)) == 0) && (ReceivedLength >= PAGE_SIZE)) { ZeroFlags |= ZERO_FIRST_PAGE; } if ((BeyondLastByte.LowPart & (PAGE_SIZE - 1)) == 0) { ZeroFlags |= ZERO_LAST_PAGE; } // // See if the entire transfer is beyond valid data length, // or at least starting from the second page. // Temp = FOffset; Temp.LowPart &= ~(PAGE_SIZE -1); ExAcquireFastLock( &SharedCacheMap->BcbSpinLock, &OldIrql ); Temp.QuadPart = SharedCacheMap->ValidDataGoal.QuadPart - Temp.QuadPart; ExReleaseFastLock( &SharedCacheMap->BcbSpinLock, OldIrql ); if (Temp.QuadPart <= 0) { ZeroFlags |= ZERO_FIRST_PAGE | ZERO_MIDDLE_PAGES | ZERO_LAST_PAGE; } else if ((Temp.HighPart == 0) && (Temp.LowPart <= PAGE_SIZE)) { ZeroFlags |= ZERO_MIDDLE_PAGES | ZERO_LAST_PAGE; } (VOID)CcMapAndRead( SharedCacheMap, &FOffset, ReceivedLength, ZeroFlags, TRUE, CacheBuffer ); // // Now attempt to allocate an Mdl to describe the mapped data. // DebugTrace( 0, mm, "IoAllocateMdl:\n", 0 ); DebugTrace( 0, mm, " BaseAddress = %08lx\n", CacheBuffer ); DebugTrace( 0, mm, " Length = %08lx\n", ReceivedLength ); Mdl = IoAllocateMdl( CacheBuffer, ReceivedLength, FALSE, FALSE, NULL ); DebugTrace( 0, mm, " <Mdl = %08lx\n", Mdl ); if (Mdl == NULL) { DebugTrace( 0, 0, "Failed to allocate Mdl\n", 0 ); ExRaiseStatus( STATUS_INSUFFICIENT_RESOURCES ); } DebugTrace( 0, mm, "MmProbeAndLockPages:\n", 0 ); DebugTrace( 0, mm, " Mdl = %08lx\n", Mdl ); MmDisablePageFaultClustering(&SavedState); MmProbeAndLockPages( Mdl, KernelMode, IoWriteAccess ); MmEnablePageFaultClustering(SavedState); SavedState = 0; // // Now that some data (maybe zeros) is locked in memory and // set dirty, it is safe, and necessary for us to advance // valid data goal, so that we will not subsequently ask // for a zero page. Note if we are extending valid data, // our caller has the file exclusive. // ExAcquireFastLock( &SharedCacheMap->BcbSpinLock, &OldIrql ); if (BeyondLastByte.QuadPart > SharedCacheMap->ValidDataGoal.QuadPart) { SharedCacheMap->ValidDataGoal = BeyondLastByte; } ExReleaseFastLock( &SharedCacheMap->BcbSpinLock, OldIrql ); // // Unmap the data now, now that the pages are locked down. // CcFreeVirtualAddress( Vacb ); Vacb = NULL; // // Now link the Mdl into the caller's chain // if ( *MdlChain == NULL ) { *MdlChain = Mdl; } else { MdlTemp = CONTAINING_RECORD( *MdlChain, MDL, Next ); while (MdlTemp->Next != NULL) { MdlTemp = MdlTemp->Next; } MdlTemp->Next = Mdl; } Mdl = NULL; // // Assume we did not get all the data we wanted, and set FOffset // to the end of the returned data. // FOffset = BeyondLastByte; // // Update number of bytes transferred. // Information += ReceivedLength; // // Calculate length left to transfer. // Length -= ReceivedLength; } } finally { if (AbnormalTermination()) { if (SavedState != 0) { MmEnablePageFaultClustering(SavedState); } if (Vacb != NULL) { CcFreeVirtualAddress( Vacb ); } if (Mdl != NULL) { IoFreeMdl( Mdl ); } // // Otherwise loop to deallocate the Mdls // FOffset = *FileOffset; while (*MdlChain != NULL) { MdlTemp = (*MdlChain)->Next; DebugTrace( 0, mm, "MmUnlockPages/IoFreeMdl:\n", 0 ); DebugTrace( 0, mm, " Mdl = %08lx\n", *MdlChain ); MmUnlockPages( *MdlChain ); // // Extract the File Offset for this part of the transfer, and // tell the lazy writer to write these pages, since we have // marked them dirty. Ignore the only exception (allocation // error), and console ourselves for having tried. // CcSetDirtyInMask( SharedCacheMap, &FOffset, (*MdlChain)->ByteCount ); FOffset.QuadPart = FOffset.QuadPart + (LONGLONG)((*MdlChain)->ByteCount); IoFreeMdl( *MdlChain ); *MdlChain = MdlTemp; } DebugTrace(-1, me, "CcPrepareMdlWrite -> Unwinding\n", 0 ); } else { IoStatus->Status = STATUS_SUCCESS; IoStatus->Information = Information; // // Make sure the SharedCacheMap does not go away while // the Mdl write is in progress. We decrment below. // CcAcquireMasterLock( &OldIrql ); CcIncrementOpenCount( SharedCacheMap, 'ldmP' ); CcReleaseMasterLock( OldIrql ); } } DebugTrace( 0, me, " <MdlChain = %08lx\n", *MdlChain ); DebugTrace(-1, me, "CcPrepareMdlWrite -> VOID\n", 0 ); return; }

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