lazy writer thread

NTFSD
1

Hello,
From a file system filter, how can I tell if I’m being called in the
context of the lazy writer thread??

Thanks,
Joel

2

lazy writer threadFilter the AcquireForLazyWrite FastIo function and save
the thread ID.

----- Original Message -----
From: Smith, Joel
To: File Systems Developers
Sent: Sunday, June 25, 2000 10:49 PM
Subject: [ntfsd] lazy writer thread

Hello,
From a file system filter, how can I tell if I’m being called in the
context of the lazy writer thread??
Thanks,
Joel

3

I believe Max is referring to the fast IO routine AcquireForCcFlush since
there is no fast IO routine by the name AcquireForLazyWrite, although there
is a cache manager callback with this name (specified when caching is
initiated for a file.) Anyway, assuming Max is talking about the fast IO
routine AcquireForCcFlush, you should know that NT provides no safe method
of filtering this routine. When the kernel invokes this fast IO routine, it
does not call attached filters. Instead the kernel bypasses the filters by
directly calling the base file system. One method of filtering this routine
is to replace the underlying file system’s fast IO entry point with your
own, then call the file system after you’ve done your processing. However,
NT’s filtering model is meant to discourage us from such brute force
actions.

-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Sunday, June 25, 2000 5:08 PM
To: File Systems Developers
Subject: [ntfsd] Re: lazy writer thread

lazy writer threadFilter the AcquireForLazyWrite FastIo
function and save
the thread ID.

----- Original Message -----
From: Smith, Joel
To: File Systems Developers
Sent: Sunday, June 25, 2000 10:49 PM
Subject: [ntfsd] lazy writer thread

Hello,
From a file system filter, how can I tell if I’m
being called in the
context of the lazy writer thread??
Thanks,
Joel

You are currently subscribed to ntfsd as: xxxxx@nsisw.com
To unsubscribe send a blank email to $subst(‘Email.Unsub’)

4

> I believe Max is referring to the fast IO routine AcquireForCcFlush since

there is no fast IO routine by the name AcquireForLazyWrite, although
there

Sorry. You’re right.
AcquireForLazyWrite is NOT an FastIo routine - it is passed to the Cc in
CcInitializeCacheMap. It is very, very hard to filter it.
Too bad MS did not use IRP flags to designate all those kinds of IO.

Max