FsContext versus FltMgr contexts

NTFSD
1

Hello all smart guys and girls !
I’m glad to welcome you again. I’ve some little question.
Today i’m read an article on the osronline about of FsContext
and support FSRTL_ADVANCED_FCB_HEADER in the FileObject.
In the FltMgr was introduced an “context” term for the stream,
streamhandle, volume, and instance related structures, which
was described in the FltMgr IfsKit.
I want to know - whther they has some regard to the FsContext’s,
which are discussed in the abovementioned article…?
Beforehand grateful
Oleg Nikitenko.

Build your own website, it’s easy and fun.

http://www.homemaster.net - Homemaster. Come Together. Online.

2

Of course Filter Manager relies upon the file contexts. Provided all of
the file systems on the machine use a common FCB header you will be
fine.

Over the years I’ve seen file systems that do not use the common header
in their file system (and, unfortunately, Microsoft has publicly stated
in the past that it is not necessary, although long enough ago now that
few people remember it). While such file systems are the exception (not
the rule, since you can’t use the cache or the FsRtl routines without a
common header) they do exist (the first time I saw an example is one
that only ran below SRV).

Regards,

Tony

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

Looking forward to seeing you at the Next OSR File Systems Class April
4, 2004 in Boston!

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of oleshii wood
Sent: Tuesday, December 14, 2004 8:25 AM
To: ntfsd redirect
Subject: [ntfsd] FsContext versus FltMgr contexts

Hello all smart guys and girls !
I’m glad to welcome you again. I’ve some little question.
Today i’m read an article on the osronline about of FsContext
and support FSRTL_ADVANCED_FCB_HEADER in the FileObject.
In the FltMgr was introduced an “context” term for the stream,
streamhandle, volume, and instance related structures, which
was described in the FltMgr IfsKit.
I want to know - whther they has some regard to the FsContext’s,
which are discussed in the abovementioned article…?
Beforehand grateful
Oleg Nikitenko.

Build your own website, it’s easy and fun.

http://www.homemaster.net - Homemaster. Come Together. Online.

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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

3

Before FSRTL_ADVANCED_FCB_HEADER, filters needed to maintain “kinda map” of
FsContext to their private structure - hash table or AVL tree or some similar
container.

With FSRTL_ADVANCED_FCB_HEADER, filters (mainly FltMgr and its minifilters)
got the ability of getting their own context structures by direct pointer or
list reference.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “oleshii wood”
To: “Windows File Systems Devs Interest List”
Sent: Tuesday, December 14, 2004 4:25 PM
Subject: [ntfsd] FsContext versus FltMgr contexts

> Hello all smart guys and girls !
> I’m glad to welcome you again. I’ve some little question.
> Today i’m read an article on the osronline about of FsContext
> and support FSRTL_ADVANCED_FCB_HEADER in the FileObject.
> In the FltMgr was introduced an “context” term for the stream,
> streamhandle, volume, and instance related structures, which
> was described in the FltMgr IfsKit.
> I want to know - whther they has some regard to the FsContext’s,
> which are discussed in the abovementioned article…?
> Beforehand grateful
> Oleg Nikitenko.
>
> ___________________________________________________
> Build your own website, it’s easy and fun.
>
> http://www.homemaster.net - Homemaster. Come Together. Online.
>
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

4

>Over the years I’ve seen file systems that do not use the common header

in their file system (and, unfortunately, Microsoft has publicly stated
in the past that it is not necessary, although long enough ago now that
few people remember it). While such file systems are the exception (not
the rule, since you can’t use the cache or the FsRtl routines without a
common header) they do exist (the first time I saw an example is one

I think they also cannot support memory-mapped files.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

5

Actually, it turns out that so long as you allow SRV access, you can
support memory mapped files via the loopback path. This is a perfectly
reasonable configuration for a server class machine. At the time (NT 4)
I thought it a little odd, but with Microsoft’s clear bifurcation of the
OS into “workstation” (XP/Longhorn) and “server” (2003/Blackcomb) this
makes more sense now than it did then.

For example, I could easily see a set of rack-mount storage machines,
accessible only via SRV, that just disallowed all local access and only
allows SRV access with some SAN back-end. That overcomes the inability
to properly support memory mapped files (no page invalidation in the
face of memory mapping) and would actually be a decent solution - but in
a tightly focused environment.

Sometimes not supporting memory mapped files can be a blessing, not a
curse…

Tony

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

Looking forward to seeing you at the Next OSR File Systems Class April
4, 2004 in Boston!

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Maxim S. Shatskih
Sent: Tuesday, December 14, 2004 9:40 AM
To: ntfsd redirect
Subject: Re: [ntfsd] FsContext versus FltMgr contexts

Over the years I’ve seen file systems that do not use the common header
in their file system (and, unfortunately, Microsoft has publicly stated
in the past that it is not necessary, although long enough ago now that
few people remember it). While such file systems are the exception
(not
the rule, since you can’t use the cache or the FsRtl routines without a
common header) they do exist (the first time I saw an example is one

I think they also cannot support memory-mapped files.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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

6

Just so everyone is clear on this. With the introduction of the filter
manager it is now a requirement for all file systems to use at least the
COMMON_FCB_HEADER and we strongly encourage all file systems to use the
AVANCED_FCB_HEADER.

If there are released file systems that don’t and it runs on W2K or
later they need to be fixed ASAP because the machine will crash when
minifilters start being released.

Neal Christiansen
Microsoft File System Filter Group Lead
This posting is provided “AS IS” with no warranties, and confers no
rights

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Tony Mason
Sent: Tuesday, December 14, 2004 6:02 AM
To: Windows File Systems Devs Interest List
Subject: RE: [ntfsd] FsContext versus FltMgr contexts

Of course Filter Manager relies upon the file contexts. Provided all of
the file systems on the machine use a common FCB header you will be
fine.

Over the years I’ve seen file systems that do not use the common header
in their file system (and, unfortunately, Microsoft has publicly stated
in the past that it is not necessary, although long enough ago now that
few people remember it). While such file systems are the exception (not
the rule, since you can’t use the cache or the FsRtl routines without a
common header) they do exist (the first time I saw an example is one
that only ran below SRV).

Regards,

Tony

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

Looking forward to seeing you at the Next OSR File Systems Class April
4, 2004 in Boston!

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of oleshii wood
Sent: Tuesday, December 14, 2004 8:25 AM
To: ntfsd redirect
Subject: [ntfsd] FsContext versus FltMgr contexts

Hello all smart guys and girls !
I’m glad to welcome you again. I’ve some little question.
Today i’m read an article on the osronline about of FsContext
and support FSRTL_ADVANCED_FCB_HEADER in the FileObject.
In the FltMgr was introduced an “context” term for the stream,
streamhandle, volume, and instance related structures, which
was described in the FltMgr IfsKit.
I want to know - whther they has some regard to the FsContext’s,
which are discussed in the abovementioned article…?
Beforehand grateful
Oleg Nikitenko.

Build your own website, it’s easy and fun.

http://www.homemaster.net - Homemaster. Come Together. Online.

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: unknown lmsubst tag argument:
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