iomdl.c File Reference

#include <ntoskrnl.h>
#include <debug.h>

Include dependency graph for iomdl.c:

Go to the source code of this file.

Macros
#define	NDEBUG

Functions
PMDL NTAPI	IoAllocateMdl (IN PVOID VirtualAddress, IN ULONG Length, IN BOOLEAN SecondaryBuffer, IN BOOLEAN ChargeQuota, IN PIRP Irp)
VOID NTAPI	IoBuildPartialMdl (IN PMDL SourceMdl, IN PMDL TargetMdl, IN PVOID VirtualAddress, IN ULONG Length)
VOID NTAPI	IoFreeMdl (PMDL Mdl)

Macro Definition Documentation

NDEBUG

#define NDEBUG

Definition at line 12 of file iomdl.c.

Function Documentation

IoAllocateMdl()

PMDL NTAPI IoAllocateMdl	(	IN PVOID	VirtualAddress,
		IN ULONG	Length,
		IN BOOLEAN	SecondaryBuffer,
		IN BOOLEAN	ChargeQuota,
		IN PIRP	Irp
	)

Definition at line 22 of file iomdl.c.

{
    PMDL Mdl = NULL, p;
    ULONG Flags = 0;
    ULONG Size;
 
    /* Make sure we got a valid length */
    ASSERT(Length != 0);
 
    /* Fail if allocation is over 2GB */
    if (Length & 0x80000000) return NULL;
 
    /* Calculate the number of pages for the allocation */
    Size = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress, Length);
    if (Size > 23)
    {
        /* This is bigger then our fixed-size MDLs. Calculate real size */
        Size *= sizeof(PFN_NUMBER);
        Size += sizeof(MDL);
        if (Size > MAXUSHORT) return NULL;
    }
    else
    {
        /* Use an internal fixed MDL size */
        Size = (23 * sizeof(PFN_NUMBER)) + sizeof(MDL);
        Flags |= MDL_ALLOCATED_FIXED_SIZE;
 
        /* Allocate one from the lookaside list */
        Mdl = IopAllocateMdlFromLookaside(LookasideMdlList);
    }
 
    /* Check if we don't have an mdl yet */
    if (!Mdl)
    {
        /* Allocate one from pool */
        Mdl = ExAllocatePoolWithTag(NonPagedPool, Size, TAG_MDL);
        if (!Mdl) return NULL;
    }
 
    /* Initialize it */
    MmInitializeMdl(Mdl, VirtualAddress, Length);
    Mdl->MdlFlags |= Flags;
 
    /* Check if an IRP was given too */
    if (Irp)
    {
        /* Check if it came with a secondary buffer */
        if (SecondaryBuffer)
        {
            /* Insert the MDL at the end */
            p = Irp->MdlAddress;
            while (p->Next) p = p->Next;
            p->Next = Mdl;
        }
        else
        {
            /* Otherwise, insert it directly */
            Irp->MdlAddress = Mdl;
        }
    }
 
    /* Return the allocated mdl */
    return Mdl;
}

IoBuildPartialMdl()

VOID NTAPI IoBuildPartialMdl	(	IN PMDL	SourceMdl,
		IN PMDL	TargetMdl,
		IN PVOID	VirtualAddress,
		IN ULONG	Length
	)

Definition at line 96 of file iomdl.c.

{
    PPFN_NUMBER TargetPages = (PPFN_NUMBER)(TargetMdl + 1);
    PPFN_NUMBER SourcePages = (PPFN_NUMBER)(SourceMdl + 1);
    ULONG Offset;
    ULONG FlagsMask = (MDL_IO_PAGE_READ |
                       MDL_SOURCE_IS_NONPAGED_POOL |
                       MDL_MAPPED_TO_SYSTEM_VA |
                       MDL_IO_SPACE);
 
    /* Calculate the offset */
    Offset = (ULONG)((ULONG_PTR)VirtualAddress -
                     (ULONG_PTR)SourceMdl->StartVa) -
                     SourceMdl->ByteOffset;
 
    /* Check if we don't have a length and calculate it */
    if (!Length) Length = SourceMdl->ByteCount - Offset;
 
    /* Write the process, start VA and byte data */
    TargetMdl->StartVa = (PVOID)PAGE_ROUND_DOWN(VirtualAddress);
    TargetMdl->Process = SourceMdl->Process;
    TargetMdl->ByteCount = Length;
    TargetMdl->ByteOffset = BYTE_OFFSET(VirtualAddress);
 
    /* Recalculate the length in pages */
    Length = ADDRESS_AND_SIZE_TO_SPAN_PAGES(VirtualAddress, Length);
 
    /* Set the MDL Flags */
    TargetMdl->MdlFlags &= (MDL_ALLOCATED_FIXED_SIZE | MDL_ALLOCATED_MUST_SUCCEED);
    TargetMdl->MdlFlags |= SourceMdl->MdlFlags & FlagsMask;
    TargetMdl->MdlFlags |= MDL_PARTIAL;
 
    /* Set the mapped VA */
    TargetMdl->MappedSystemVa = (PCHAR)SourceMdl->MappedSystemVa + Offset;
 
    /* Now do the copy */
    Offset = (ULONG)(((ULONG_PTR)TargetMdl->StartVa -
                      (ULONG_PTR)SourceMdl->StartVa) >> PAGE_SHIFT);
    SourcePages += Offset;
    RtlCopyMemory(TargetPages, SourcePages, Length * sizeof(PFN_NUMBER));
}

Referenced by __attribute__(), _Requires_lock_held_(), CdMultipleXAAsync(), Ext2ReadWriteBlocks(), FatMultipleAsync(), FatPagingFileIo(), FreeBT_DispatchRead(), FreeBT_DispatchWrite(), FreeBT_WriteCompletion(), Mx::MxBuildPartialMdl(), NdisCopyBuffer(), ScratchBuffer_SetupReadWriteSrb(), SubmitTransferPacket(), USBSTOR_CBWCompletionRoutine(), USBSTOR_SendRequest(), VfatReadDiskPartial(), and VfatWriteDiskPartial().

IoFreeMdl()

VOID NTAPI IoFreeMdl

(

PMDL

Mdl

)

Definition at line 146 of file iomdl.c.

{
    /* Tell Mm to reuse the MDL */
    MmPrepareMdlForReuse(Mdl);
 
    /* Check if this was a pool allocation */
    if (!(Mdl->MdlFlags & MDL_ALLOCATED_FIXED_SIZE))
    {
        /* Free it from the pool */
        ExFreePoolWithTag(Mdl, TAG_MDL);
    }
    else
    {
        /* Free it from the lookaside */
        IopFreeMdlFromLookaside(Mdl, LookasideMdlList);
    }
}