close.c

winddk src目录下的文件系统驱动源码压缩!

/*++

Copyright (c) 1989-2000 Microsoft Corporation

Module Name:

    Close.c

Abstract:

    This module implements the File Close routine for Cdfs called by the
    Fsd/Fsp dispatch routines.

    The close operation interacts with both the async and delayed close queues
    in the CdData structure.  Since close may be called recursively we may
    violate the locking order in acquiring the Vcb or Fcb.  In this case
    we may move the request to the async close queue.  If this is the last
    reference on the Fcb and there is a chance the user may reopen this
    file again soon we would like to defer the close.  In this case we
    may move the request to the async close queue.

    Once we are past the decode file operation there is no need for the
    file object.  If we are moving the request to either of the work
    queues then we remember all of the information from the file object and
    complete the request with STATUS_SUCCESS.  The Io system can then
    reuse the file object and we can complete the request when convenient.

    The async close queue consists of requests which we would like to
    complete as soon as possible.  They are queued using the original
    IrpContext where some of the fields have been overwritten with
    information from the file object.  We will extract this information,
    cleanup the IrpContext and then call the close worker routine.

    The delayed close queue consists of requests which we would like to
    defer the close for.  We keep size of this list within a range
    determined by the size of the system.  We let it grow to some maximum
    value and then shrink to some minimum value.  We allocate a small
    structure which contains the key information from the file object
    and use this information along with an IrpContext on the stack
    to complete the request.


--*/

#include "CdProcs.h"

//
//  The Bug check file id for this module
//

#define BugCheckFileId                   (CDFS_BUG_CHECK_CLOSE)

//
//  Local support routines
//

BOOLEAN
CdCommonClosePrivate (
    IN PIRP_CONTEXT IrpContext,
    IN PVCB Vcb,
    IN PFCB Fcb,
    IN ULONG UserReference,
    IN BOOLEAN FromFsd
    );

VOID
CdQueueClose (
    IN PIRP_CONTEXT IrpContext,
    IN PFCB Fcb,
    IN ULONG UserReference,
    IN BOOLEAN DelayedClose
    );

PIRP_CONTEXT
CdRemoveClose (
    IN PVCB Vcb OPTIONAL
    );

VOID
CdCloseWorker (
    IN PDEVICE_OBJECT DeviceObject,
    IN PVOID Context
    );

#ifdef ALLOC_PRAGMA
#pragma alloc_text(PAGE, CdCommonClose)
#pragma alloc_text(PAGE, CdCommonClosePrivate)
#pragma alloc_text(PAGE, CdQueueClose)
#pragma alloc_text(PAGE, CdRemoveClose)
#pragma alloc_text(PAGE, CdCloseWorker)
#endif


VOID
CdFspClose (
    IN PVCB Vcb OPTIONAL
    )

/*++

Routine Description:

    This routine is called to process the close queues in the CdData.  If the
    Vcb is passed then we want to remove all of the closes for this Vcb.
    Otherwise we will do as many of the delayed closes as we need to do.

Arguments:

    Vcb - If specified then we are looking for all of the closes for the
        given Vcb.

Return Value:

    None

--*/

{
    PIRP_CONTEXT IrpContext;
    IRP_CONTEXT StackIrpContext;

    THREAD_CONTEXT ThreadContext;

    PFCB Fcb;
    ULONG UserReference;

    ULONG VcbHoldCount = 0;
    PVCB CurrentVcb = NULL;

    BOOLEAN PotentialVcbTeardown = FALSE;

    PAGED_CODE();

    FsRtlEnterFileSystem();

    //
    //  Continue processing until there are no more closes to process.
    //

    while (IrpContext = CdRemoveClose( Vcb )) {

        //
        //  If we don't have an IrpContext then use the one on the stack.
        //  Initialize it for this request.
        //

        if (SafeNodeType( IrpContext ) != CDFS_NTC_IRP_CONTEXT ) {

            //
            //  Update the local values from the IrpContextLite.
            //

            Fcb = ((PIRP_CONTEXT_LITE) IrpContext)->Fcb;
            UserReference = ((PIRP_CONTEXT_LITE) IrpContext)->UserReference;

            //
            //  Update the stack irp context with the values from the
            //  IrpContextLite.
            //

            CdInitializeStackIrpContext( &StackIrpContext,
                                         (PIRP_CONTEXT_LITE) IrpContext );

            //
            //  Free the IrpContextLite.
            //

            CdFreeIrpContextLite( (PIRP_CONTEXT_LITE) IrpContext );

            //
            //  Remember we have the IrpContext from the stack.
            //

            IrpContext = &StackIrpContext;

        //
        //  Otherwise cleanup the existing IrpContext.
        //

        } else {

            //
            //  Remember the Fcb and user reference count.
            //

            Fcb = (PFCB) IrpContext->Irp;
            IrpContext->Irp = NULL;

            UserReference = (ULONG) IrpContext->ExceptionStatus;
            IrpContext->ExceptionStatus = STATUS_SUCCESS;
        }

        //
        //  We have an IrpContext.  Now we need to set the top level thread
        //  context.
        //

        SetFlag( IrpContext->Flags, IRP_CONTEXT_FSP_FLAGS );

        //
        //  If we were given a Vcb then there is a request on top of this.
        //

        if (ARGUMENT_PRESENT( Vcb )) {

            ClearFlag( IrpContext->Flags,
                       IRP_CONTEXT_FLAG_TOP_LEVEL | IRP_CONTEXT_FLAG_TOP_LEVEL_CDFS );
        }

        CdSetThreadContext( IrpContext, &ThreadContext );

        //
        //  If we have hit the maximum number of requests to process without
        //  releasing the Vcb then release the Vcb now.  If we are holding
        //  a different Vcb to this one then release the previous Vcb.
        //
        //  In either case acquire the current Vcb.
        //
        //  We use the MinDelayedCloseCount from the CdData since it is
        //  a convenient value based on the system size.  Only thing we are trying
        //  to do here is prevent this routine starving other threads which
        //  may need this Vcb exclusively.
        //
        //  Note that the check for potential teardown below is unsafe.  We'll 
        //  repeat later within the cddata lock.
        //

        PotentialVcbTeardown = !ARGUMENT_PRESENT( Vcb ) &&
                               (Fcb->Vcb->VcbCondition != VcbMounted) &&
                               (Fcb->Vcb->VcbCondition != VcbMountInProgress) &&
                               (Fcb->Vcb->VcbCleanup == 0);

        if (PotentialVcbTeardown ||
            (VcbHoldCount > CdData.MinDelayedCloseCount) ||
            (Fcb->Vcb != CurrentVcb)) {

            if (CurrentVcb != NULL) {

                CdReleaseVcb( IrpContext, CurrentVcb );
            }

            if (PotentialVcbTeardown) {

                CdAcquireCdData( IrpContext );

                //
                //  Repeat the checks with global lock held.  The volume could have
                //  been remounted while we didn't hold the lock.
                //

                PotentialVcbTeardown = !ARGUMENT_PRESENT( Vcb ) &&
                                       (Fcb->Vcb->VcbCondition != VcbMounted) &&
                                       (Fcb->Vcb->VcbCondition != VcbMountInProgress) &&
                                       (Fcb->Vcb->VcbCleanup == 0);
                                
                if (!PotentialVcbTeardown)  {

                    CdReleaseCdData( IrpContext);
                }
            }

            CurrentVcb = Fcb->Vcb;
            CdAcquireVcbShared( IrpContext, CurrentVcb, FALSE );

            VcbHoldCount = 0;

        } else {

            VcbHoldCount += 1;
        }

        //
        //  Call our worker routine to perform the close operation.
        //

        CdCommonClosePrivate( IrpContext, CurrentVcb, Fcb, UserReference, FALSE );

        //
        //  If the reference count on this Vcb is below our residual reference
        //  then check if we should dismount the volume.
        //

        if (PotentialVcbTeardown) {

            CdReleaseVcb( IrpContext, CurrentVcb );
            CdCheckForDismount( IrpContext, CurrentVcb, FALSE );

            CurrentVcb = NULL;

            CdReleaseCdData( IrpContext );
            PotentialVcbTeardown = FALSE;
        }

        //
        //  Complete the current request to cleanup the IrpContext.
        //

        CdCompleteRequest( IrpContext, NULL, STATUS_SUCCESS );
    }

    //
    //  Release any Vcb we may still hold.
    //

    if (CurrentVcb != NULL) {

        CdReleaseVcb( IrpContext, CurrentVcb );

    }

    FsRtlExitFileSystem();
}


NTSTATUS
CdCommonClose (
    IN PIRP_CONTEXT IrpContext,
    IN PIRP Irp
    )

/*++

Routine Description:

    This routine is the Fsd entry for the close operation.  We decode the file
    object to find the CDFS structures and type of open.  We call our internal
    worker routine to perform the actual work.  If the work wasn't completed
    then we post to one of our worker queues.  The Ccb isn't needed after this
    point so we delete the Ccb and return STATUS_SUCCESS to our caller in all
    cases.

Arguments:

    Irp - Supplies the Irp to process

Return Value:

    STATUS_SUCCESS

--*/

{
    TYPE_OF_OPEN TypeOfOpen;

    PVCB Vcb;
    PFCB Fcb;
    PCCB Ccb;
    ULONG UserReference = 0;

    BOOLEAN PotentialVcbTeardown = FALSE;
    BOOLEAN ForceDismount = FALSE;

    PAGED_CODE();

    ASSERT_IRP_CONTEXT( IrpContext );
    ASSERT_IRP( Irp );

    //
    //  If we were called with our file system device object instead of a
    //  volume device object, just complete this request with STATUS_SUCCESS.
    //

    if (IrpContext->Vcb == NULL) {

        CdCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
        return STATUS_SUCCESS;
    }

    //
    //  Decode the file object to get the type of open and Fcb/Ccb.
    //

    TypeOfOpen = CdDecodeFileObject( IrpContext,
                                     IoGetCurrentIrpStackLocation( Irp )->FileObject,
                                     &Fcb,
                                     &Ccb );

    //
    //  No work to do for unopened file objects.
    //

    if (TypeOfOpen == UnopenedFileObject) {

        CdCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );

        return STATUS_SUCCESS;
    }

    Vcb = Fcb->Vcb;

    //
    //  Clean up any CCB associated with this open.
    //
    
    if (Ccb != NULL) {

        UserReference = 1;

        //
        //  Was a FSCTL_DISMOUNT issued on this handle?  If so,  we need to
        //  force a dismount of the volume now.
        //
        
        ForceDismount = BooleanFlagOn( Ccb->Flags, CCB_FLAG_DISMOUNT_ON_CLOSE);

        //
        //  We can always deallocate the Ccb if present.
        //

        CdDeleteCcb( IrpContext, Ccb );
    }

    //
    //  If this is the last reference to a user file or directory on a 
    //  currently mounted volume, then post it to the delayed close queue.  Note
    //  that the VcbCondition check is unsafe,  but it doesn't really matter -
    //  we just might delay the volume teardown a little by posting this close.
    //

    if ((Vcb->VcbCondition == VcbMounted) &&
        (Fcb->FcbReference == 1) &&
        ((TypeOfOpen == UserFileOpen) ||
         (TypeOfOpen == UserDirectoryOpen))) {

        CdQueueClose( IrpContext, Fcb, UserReference, TRUE );
        IrpContext = NULL;

    //
    //  Otherwise try to process this close.  Post to the async close queue
    //  if we can't acquire all of the resources.
    //

    } 
    else {

        //
        //  If we may be dismounting this volume then acquire the CdData
        //  resource.
        //
        //  Since we now must make volumes go away as soon as reasonable after
        //  the last user handles closes, key off of the cleanup count.  It is
        //  OK to do this more than neccesary.  Since this Fcb could be holding
        //  a number of other Fcbs (and thus their references), a simple check
        //  on reference count is not appropriate.
        //
        //  Do an unsafe check first to avoid taking the (global) cddata lock in the 
        //  common case.
        //

        if (((Vcb->VcbCleanup == 0) || ForceDismount) &&
            (Vcb->VcbCondition != VcbMounted))  {

            //
            //  Note that we must send the notification outside of any locks,  since 
            //  the worker that processes the notify could also be calling into our 
            //  pnp path which wants both CdData and VcbResource.  For a force dismount
            //  the volume will be marked invalid (no going back),  so we will definitely
            //  go ahead and dismount below.
            //

            if (ForceDismount)  {
            
                //
                //  Send notification.
                //
                
                FsRtlNotifyVolumeEvent( IoGetCurrentIrpStackLocation( Irp )->FileObject, 
                                        FSRTL_VOLUME_DISMOUNT );
            }

            //
            //  Possible dismount.  Acquire UdfData to synchronise with the remount path
            //  before looking at the vcb condition again.
            //

            CdAcquireCdData( IrpContext );

            if (((Vcb->VcbCleanup == 0) || ForceDismount) &&
                (Vcb->VcbCondition != VcbMounted) &&
                (Vcb->VcbCondition != VcbMountInProgress) &&
                FlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_TOP_LEVEL_CDFS ))  {

                PotentialVcbTeardown = TRUE;
            }
            else {

                //
                //  We can't dismount this volume now,  there are other references or
                //  it's just been remounted.
                //
            }

            //
            //  For a force dismount, physically disconnect this Vcb from the device so 
            //  a new mount can occur.  Vcb deletion cannot happen at this time since 
            //  there is a reference on it associated with this very request,  but we'll 
            //  call check for dismount again later after we process this close.
            //

            if (ForceDismount)  {
                        
                CdCheckForDismount( IrpContext, Vcb, TRUE );
            }
            
            //
            //  Drop the global lock if we don't need it anymore.
            //

            if (!PotentialVcbTeardown) {

                CdReleaseCdData( IrpContext );
            }
        }
        
        //
        //  Call the worker routine to perform the actual work.  This routine
        //  should never raise except for a fatal error.
        //