virtual file system

Hi all:

I apologize if this is a FAQ; I went through most of the archive on
atria.com for 1999-2000 and didn’t see much relevant to this…

I’m trying to build a virtual disk driver under an existing W2000 FSD. I.e.,
I’d like to create a drive (e.g., X:) for which all Win32 file operations
get funnelled to the NTFS driver, and thence to my virtual disk driver.

I’d like my driver to just get the sector read/write requests from the NTFS
FSD, so I can handle them as I see fit. I don’t want to create my own
filesystem (for now at least).

I’m looking at Filemon, and I saw Tony’s reply to “How to mount a virtual
file system” last February, but I’m still unclear how I can hook my virtual
disk driver to an existing FSD, but only handling file requests for those
files on the new drive I’ve created. I have looked at both the Nagar book
as well as Peter/Tony’s book.

Any ideas, however elementary, would be much appreciated.

Thanks,
Curt


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Curt,

What you are trying to build is a pseudo disk drive, not a file system,
which is probably why the earlier questions didn’t make much sense.

If you decide to implement it as a port driver, the disk class driver will
handle everything else for you (creating the partition table, making the
partitions available, creating device objects for the partitions.) Then you
don’t need to even worry about the file systems, because they will “just
mount.”

Thus, you’d just look like any other port (or even mini-port!) driver.

If you decide to implement it as a disk driver, you’ll be responsible for
creating the partition device objects. In that case, you should use the
disk class driver sample in the DDK to guide your efforts. Again, the
mounting of the file system will just happen.

Mounting a file system occurs anytime the I/O Manager finds a device object
(during a name parse) that has a VPB but no corresponding mounted file
system. In that case, then, it asks the registered file systems to mount
the device until one of them does so (and RAW always does so, but it is
asked LAST so all other file systems have an opportunity to mount first.)

I hope this helps.

Regards,

Tony

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

-----Original Message-----
From: Curt Wohlgemuth [mailto:xxxxx@hotmail.com]
Sent: Wednesday, May 24, 2000 9:28 PM
To: File Systems Developers
Subject: [ntfsd] virtual file system

Hi all:

I apologize if this is a FAQ; I went through most of the archive on
atria.com for 1999-2000 and didn’t see much relevant to this…

I’m trying to build a virtual disk driver under an existing W2000 FSD. I.e.,

I’d like to create a drive (e.g., X:) for which all Win32 file operations
get funnelled to the NTFS driver, and thence to my virtual disk driver.

I’d like my driver to just get the sector read/write requests from the NTFS
FSD, so I can handle them as I see fit. I don’t want to create my own
filesystem (for now at least).

I’m looking at Filemon, and I saw Tony’s reply to “How to mount a virtual
file system” last February, but I’m still unclear how I can hook my virtual
disk driver to an existing FSD, but only handling file requests for those
files on the new drive I’ve created. I have looked at both the Nagar book
as well as Peter/Tony’s book.

Any ideas, however elementary, would be much appreciated.

Thanks,
Curt


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