IoCreateStreamFileObject call during volume mount

OSR_Community_User · January 23, 2002, 11:53pm

Hi!
I have a doubt regarding the
IoCreateStreamFileObject call. I make this call when I
am mounting my FS. I do this to create a file object
for my (about to be) mounted volume. This is what I
do.

PtrVCB->PtrStreamFileObject =
IoCreateStreamFileObject(NULL,
PtrVCB->PtrVPB->RealDevice);
I do this after setting the VPB DeviceObject
pointer to point to my new Volume device.

PtrVPB->DeviceObject = PtrVolumeDeviceObject;

Now, my problem is that the
IoCreateStreamFileObject call calls my IRP_MJ_CLEANUP
handler before returning. Is this the normal
behaviour? I don’t understand how I could get a
IRP_MJ_CLEANUP when I am not even done creating the
File Object! Why is the file object being closed?

This is the call stack.
mydrvr!MydrvrCleanup+0x2d
nt!IofCallDriver+0x37
nt!IopCloseFile+0x297
nt!ObpDecrementHandleCount+0x111
nt!NtClose+0x170
nt!IoCreateStreamFileObject+0x10d
mydrvr!MydrvrInitializeVCB+0x133
mydrvr!MydrvrMountVolume+0x1bf
mydrvr!MydrvrFSControl+0x2c
nt!IofCallDriver+0x37
nt!IopMountVolume+0x186
nt!IopCheckVpbMounted+0x38
nt!IopParseDevice+0x3ba
nt!ObpLookupObjectName+0x283
nt!ObOpenObjectByName+0xbb
nt!IoCreateFile+0x436
nt!NtOpenFile+0x25
nt!KiSystemService+0xc4
NTDLL!NtOpenFile+0xb
0x1094ede

Can anyone explain?
Thanks in advance!
Manoj Paul Joseph

=====

Manoj Paul Joseph,
Master of Computer Applications (final year student),
School of Computer Science and Engineering,
Anna University,
Chennai (Madras),
India.

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OSR_Community_User · January 24, 2002, 3:38am

This is normal expected behavior. Since stream file objects are
internal to the kernel they do not need a handle (this API has no handle
return value). After creating the file object, IoCreateStreamFileObject
closes the handle which causes the handle count to go to zero which is
what triggers the IRP_MJ_CLEANUP call.

Neal Christiansen
Microsoft Corporation

This posting is provided “AS IS” with no warranties, and confers no
rights.

-----Original Message-----
From: Manoj Paul Joseph [mailto:xxxxx@yahoo.com]
Sent: Wednesday, January 23, 2002 08:51 PM
To: File Systems Developers
Subject: [ntfsd] IoCreateStreamFileObject call during volume mount

Hi!
I have a doubt regarding the
IoCreateStreamFileObject call. I make this call when I
am mounting my FS. I do this to create a file object
for my (about to be) mounted volume. This is what I
do.

PtrVCB->PtrStreamFileObject =
IoCreateStreamFileObject(NULL,
PtrVCB->PtrVPB->RealDevice);
I do this after setting the VPB DeviceObject
pointer to point to my new Volume device.

PtrVPB->DeviceObject = PtrVolumeDeviceObject;

Now, my problem is that the
IoCreateStreamFileObject call calls my IRP_MJ_CLEANUP
handler before returning. Is this the normal
behaviour? I don’t understand how I could get a
IRP_MJ_CLEANUP when I am not even done creating the
File Object! Why is the file object being closed?

This is the call stack.
mydrvr!MydrvrCleanup+0x2d
nt!IofCallDriver+0x37
nt!IopCloseFile+0x297
nt!ObpDecrementHandleCount+0x111
nt!NtClose+0x170
nt!IoCreateStreamFileObject+0x10d
mydrvr!MydrvrInitializeVCB+0x133
mydrvr!MydrvrMountVolume+0x1bf
mydrvr!MydrvrFSControl+0x2c
nt!IofCallDriver+0x37
nt!IopMountVolume+0x186
nt!IopCheckVpbMounted+0x38
nt!IopParseDevice+0x3ba
nt!ObpLookupObjectName+0x283
nt!ObOpenObjectByName+0xbb
nt!IoCreateFile+0x436
nt!NtOpenFile+0x25
nt!KiSystemService+0xc4
NTDLL!NtOpenFile+0xb
0x1094ede

Can anyone explain?
Thanks in advance!
Manoj Paul Joseph

=====

Manoj Paul Joseph,
Master of Computer Applications (final year student),
School of Computer Science and Engineering,
Anna University,
Chennai (Madras),
India.

Do You Yahoo!?
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OSR_Community_User · January 24, 2002, 5:45am

This is the standard and correct behavior. If you do not wish to receive
the IRP_MJ_CLEANUP operation you should call IoCreateStreamFileObjectLite.

For either call you do NOT have a handle - only an object reference. In the
IoCreateStreamFileObject case the OS creates and then discards the handle,
which causes the handle reference to drop to zero (which triggers the
IRP_MJ_CLEANUP). In the IoCreateStreamFileObjectLite case the OS doesn’t
create a handle so no IRP_MJ_CLEANUP is triggered.

Regards,

Tony

Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com

-----Original Message-----
From: Manoj Paul Joseph [mailto:xxxxx@yahoo.com]
Sent: Wednesday, January 23, 2002 11:51 PM
To: File Systems Developers
Subject: [ntfsd] IoCreateStreamFileObject call during volume mount

Hi!
I have a doubt regarding the
IoCreateStreamFileObject call. I make this call when I
am mounting my FS. I do this to create a file object
for my (about to be) mounted volume. This is what I
do.

PtrVCB->PtrStreamFileObject =
IoCreateStreamFileObject(NULL,
PtrVCB->PtrVPB->RealDevice);
I do this after setting the VPB DeviceObject
pointer to point to my new Volume device.

PtrVPB->DeviceObject = PtrVolumeDeviceObject;

Now, my problem is that the
IoCreateStreamFileObject call calls my IRP_MJ_CLEANUP
handler before returning. Is this the normal
behaviour? I don’t understand how I could get a
IRP_MJ_CLEANUP when I am not even done creating the
File Object! Why is the file object being closed?

This is the call stack.
mydrvr!MydrvrCleanup+0x2d
nt!IofCallDriver+0x37
nt!IopCloseFile+0x297
nt!ObpDecrementHandleCount+0x111
nt!NtClose+0x170
nt!IoCreateStreamFileObject+0x10d
mydrvr!MydrvrInitializeVCB+0x133
mydrvr!MydrvrMountVolume+0x1bf
mydrvr!MydrvrFSControl+0x2c
nt!IofCallDriver+0x37
nt!IopMountVolume+0x186
nt!IopCheckVpbMounted+0x38
nt!IopParseDevice+0x3ba
nt!ObpLookupObjectName+0x283
nt!ObOpenObjectByName+0xbb
nt!IoCreateFile+0x436
nt!NtOpenFile+0x25
nt!KiSystemService+0xc4
NTDLL!NtOpenFile+0xb
0x1094ede

Can anyone explain?
Thanks in advance!
Manoj Paul Joseph

=====

Manoj Paul Joseph,
Master of Computer Applications (final year student),
School of Computer Science and Engineering,
Anna University,
Chennai (Madras),
India.

Do You Yahoo!?
Everything you’ll ever need on one web page
from News and Sport to Email and Music Charts
http://uk.my.yahoo.com

You are currently subscribed to ntfsd as: xxxxx@osr.com
To unsubscribe send a blank email to leave-ntfsd-$subst(‘Recip.MemberIDChar’)@lists.osr.com

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