Question about the file system at boot time

NTFSD
1

Hello everybody,

as the few documentation states, the real file system takes control over the
boot volume somewhere after the boot start drivers have been initialized. If
so, I wonder if there is any interaction between the boot file system and
the real file system, to do it seamlessly. What do I have to do, to connect
an FS filter immediately after the real file system took over control?

Regards, Tobias

2

Install your filter with the SERVICE_BOOT_START start type and put it in
the “filter” load order group. XP also defined multiple additional load
order groups for additional classes of filesystem filters. They are all
loaded before the protected-mode filesystem drivers are started
(according to the ServiceGroupOrder registry key).

  • Nick Ryan

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Tobias
Sent: Tuesday, June 03, 2003 2:16 PM
To: File Systems Developers
Subject: [ntfsd] Question about the file system at boot time

Hello everybody,

as the few documentation states, the real file system takes
control over the boot volume somewhere after the boot start
drivers have been initialized. If so, I wonder if there is
any interaction between the boot file system and the real
file system, to do it seamlessly. What do I have to do, to
connect an FS filter immediately after the real file system
took over control?

Regards, Tobias

You are currently subscribed to ntfsd as: xxxxx@nryan.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

3

Thanks Nick, what I actually have is a combination of an FS filter and a
storage filter. What I do is to provide a volume snapshop. The storage
filter is responsible for logging any changes that have been applied since
the last snapshot has started. The FS filter is responsible for providing
the snapshot data and monitoring user operations. So let me extend my
question:

Will my storage filter only catch IO produced by the real FS (and not the
boot FS) when it is activated from the initialization routine of my FS
filter, so starting it’s work together with the Filter group drivers?

If so, will this be sufficient to reflect a conclusive state of the volume?

Regards,
Tobias

----- Original Message -----
From: “Nick Ryan”
To: “File Systems Developers”
Sent: Wednesday, June 04, 2003 12:47 AM
Subject: [ntfsd] RE: Question about the file system at boot time

> Install your filter with the SERVICE_BOOT_START start type and put it in
> the “filter” load order group. XP also defined multiple additional load
> order groups for additional classes of filesystem filters. They are all
> loaded before the protected-mode filesystem drivers are started
> (according to the ServiceGroupOrder registry key).
>
> - Nick Ryan
>
> > -----Original Message-----
> > From: xxxxx@lists.osr.com
> > [mailto:xxxxx@lists.osr.com] On Behalf Of Tobias
> > Sent: Tuesday, June 03, 2003 2:16 PM
> > To: File Systems Developers
> > Subject: [ntfsd] Question about the file system at boot time
> >
> >
> > Hello everybody,
> >
> > as the few documentation states, the real file system takes
> > control over the boot volume somewhere after the boot start
> > drivers have been initialized. If so, I wonder if there is
> > any interaction between the boot file system and the real
> > file system, to do it seamlessly. What do I have to do, to
> > connect an FS filter immediately after the real file system
> > took over control?
> >
> > Regards, Tobias

4

Any NT storage filter you load will only be on the NT storage stack, so
you should never see any I/O generated by the boot-time filesystem
(which I believe just invokes int 13 to access the disk). If you
register your storage filter as an upper disk class filter, it should be
loaded as soon as the device objects for the partitions are created
(which is BEFORE filesystem filter are loaded). If you don’t need NT4
compatibility I suggest doing it this way instead of loading and
attaching the storage filter yourself.

Jamey has more experience in this area I think, maybe he can comment.

  • Nick Ryan

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Tobias
Sent: Tuesday, June 03, 2003 11:32 PM
To: File Systems Developers
Subject: [ntfsd] RE: Question about the file system at boot time

Thanks Nick, what I actually have is a combination of an FS
filter and a storage filter. What I do is to provide a volume
snapshop. The storage filter is responsible for logging any
changes that have been applied since the last snapshot has
started. The FS filter is responsible for providing the
snapshot data and monitoring user operations. So let me extend my
question:

Will my storage filter only catch IO produced by the real FS
(and not the boot FS) when it is activated from the
initialization routine of my FS filter, so starting it’s work
together with the Filter group drivers?

If so, will this be sufficient to reflect a conclusive state
of the volume?

Regards,
Tobias

----- Original Message -----
From: “Nick Ryan”
> To: “File Systems Developers”
> Sent: Wednesday, June 04, 2003 12:47 AM
> Subject: [ntfsd] RE: Question about the file system at boot time
>
>
> > Install your filter with the SERVICE_BOOT_START start type
> and put it
> > in the “filter” load order group. XP also defined multiple
> additional
> > load order groups for additional classes of filesystem
> filters. They
> > are all loaded before the protected-mode filesystem drivers are
> > started (according to the ServiceGroupOrder registry key).
> >
> > - Nick Ryan
> >
> > > -----Original Message-----
> > > From: xxxxx@lists.osr.com
> > > [mailto:xxxxx@lists.osr.com] On Behalf Of Tobias
> > > Sent: Tuesday, June 03, 2003 2:16 PM
> > > To: File Systems Developers
> > > Subject: [ntfsd] Question about the file system at boot time
> > >
> > >
> > > Hello everybody,
> > >
> > > as the few documentation states, the real file system
> takes control
> > > over the boot volume somewhere after the boot start drivers have
> > > been initialized. If so, I wonder if there is any interaction
> > > between the boot file system and the real file system, to do it
> > > seamlessly. What do I have to do, to connect an FS filter
> > > immediately after the real file system took over control?
> > >
> > > Regards, Tobias
>
>
>
> —
> You are currently subscribed to ntfsd as: xxxxx@nryan.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

5

Boot volume immediately mounts the real FS. No recognizers.
Look at SFILTER sample, base your code on it, and load in “filter”
group.

Max

----- Original Message -----
From: “Tobias”
To: “File Systems Developers”
Sent: Wednesday, June 04, 2003 1:16 AM
Subject: [ntfsd] Question about the file system at boot time

> Hello everybody,
>
> as the few documentation states, the real file system takes control
over the
> boot volume somewhere after the boot start drivers have been
initialized. If
> so, I wonder if there is any interaction between the boot file
system and
> the real file system, to do it seamlessly. What do I have to do, to
connect
> an FS filter immediately after the real file system took over
control?
>
> Regards, Tobias
>
>
>
> —
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com