how to mount a virtual filesystem?

NTFSD
1

Hi,

I’m testing the waters with a couple of different approaches for
implementing a virtual filesystem (it presents files, but those files
are not necessarily stored on a physical device). One approach is to
filter a particular branch of an existing filesystem, and it was
relatively easy to get a filter driver up and working well enough to
experiment with.

Another approach I’m interested in is to write a standalone filesystem
driver, but I’m hung up on how to mount my filesystem considering that
it’s virtual and does not have any disk device to recognize and mount.
Do I need to create a virtual disk device for my virtual filesystem to
mount? If anyone could point me in the right direction, I’d appreciate
it. Rajeev Nagar’s Windows NT File System Internals book covers a lot,
but it doesn’t seem to go into enough detail for me on the subject of
actually getting your filesystem actually active on a system.

Thanks in advance,
Derrick Whittle

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2

Derric:

With your second approach in your FS driver you can:

  1. Create a device of type FILE_DEVICE_DISK_FILE_SYSTEM and regiter it with
    I/O Manager via IoRegisterFileSystem. This device (FS Recognizer) will
    receive and handle IRP_MJ_FILE_SYSTEM_CONTROL/IRP_MN_MOUNT_VOLUME requests.
  2. Create device of type FILE_DEVICE_DISK, create a symbolic link to this
    device with desired driver letter. When this drive is first accessed, I/O
    Manager will issue mount request that your FS Recognizer from step 1 will
    handle and create your FS device.

Good luck! :wink:

Vladimir

-----Original Message-----
From: Derrick Whittle [mailto:xxxxx@yahoo.com]
Sent: Friday, June 22, 2001 8:09 AM
To: File Systems Developers
Subject: [ntfsd] how to mount a virtual filesystem?

Hi,

I’m testing the waters with a couple of different approaches for
implementing a virtual filesystem (it presents files, but those files
are not necessarily stored on a physical device). One approach is to
filter a particular branch of an existing filesystem, and it was
relatively easy to get a filter driver up and working well enough to
experiment with.

Another approach I’m interested in is to write a standalone filesystem
driver, but I’m hung up on how to mount my filesystem considering that
it’s virtual and does not have any disk device to recognize and mount.
Do I need to create a virtual disk device for my virtual filesystem to
mount? If anyone could point me in the right direction, I’d appreciate
it. Rajeev Nagar’s Windows NT File System Internals book covers a lot,
but it doesn’t seem to go into enough detail for me on the subject of
actually getting your filesystem actually active on a system.

Thanks in advance,
Derrick Whittle

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3

Since there’s no physical media to be concerned with, the concept of
mounting doesn’t apply. Network redirectors are like this. Just create
your file-system volume device object, and you’re done. Though you may
have to do something to help with drive-letter assignment.

Dave Cox
Hewlett-Packard Co.
SSO/OVBU/SRM (Santa Barbara)
https://ecardfile.com/id/Dave+Cox

-----Original Message-----
From: Derrick Whittle [mailto:xxxxx@yahoo.com]
Sent: Friday, June 22, 2001 8:09 AM
To: File Systems Developers
Subject: [ntfsd] how to mount a virtual filesystem?

Hi,

I’m testing the waters with a couple of different approaches for
implementing a virtual filesystem (it presents files, but those files
are not necessarily stored on a physical device). One approach is to
filter a particular branch of an existing filesystem, and it was
relatively easy to get a filter driver up and working well enough to
experiment with.

Another approach I’m interested in is to write a standalone filesystem
driver, but I’m hung up on how to mount my filesystem considering that
it’s virtual and does not have any disk device to recognize
and mount.
Do I need to create a virtual disk device for my virtual filesystem to
mount? If anyone could point me in the right direction, I’d
appreciate
it. Rajeev Nagar’s Windows NT File System Internals book
covers a lot,
but it doesn’t seem to go into enough detail for me on the subject of
actually getting your filesystem actually active on a system.

Thanks in advance,
Derrick Whittle

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4

> Another approach I’m interested in is to write a standalone filesystem

driver, but I’m hung up on how to mount my filesystem considering that
it’s virtual and does not have any disk device to recognize and mount.

Mount it as a network redirector.
Invent your own semantics for “server” and “share” part of the UNC paths.

BTW - we already have a framework for user-mode redirectors - maybe it will
be a good idea for you to license it?

Max

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