Observations on File System Filter Drivers

Observations on File System Filter Drivers
Ó 2000 OSR Open Systems Resources, Inc.

 

Having worked with file system filter drivers in various versions of Windows NT, we have noticed some new tools and issues for Windows 2000 file system filter driver writers that have an effect on their development.  This article attempts to capture those observations in hopes that they will help those developing, or attempting to develop, file system filter drivers in the future.

 

The “big issues” as far as we can tell continue to remain pretty much the same for file system filter driver writers:

 

?    Reentrant operations

?    IRQL levels

?    Mapping between file objects and files

?    Dealing with removable media

?    Dealing with naming

?    Understanding file system semantics

 

Some things have changed in Windows 2000, however, and we thought it was time to discuss some of those issues (and review a few old issues in the process) in The NT Insider so that we can share some of our hard-won experience with others.

 

Device Attachment
Figuring out how to manage device attachment has always been a problem in Windows NT.  For example, there is the perennial problem with respect to load ordering of two file system filter drivers.  In Windows 2000 this problem is less difficult than in previous Windows NT versions, because the CIFS/SMB network redirector now registers as a file system.  Thus, its loading can be detected by a file system filter driver.

 

In earlier versions of Windows NT, it was necessary to “find out” when a network redirector loaded using some other scheme.  Even in Windows 2000, this problem remains for those filter drivers that filter the NCP (NetWare) network redirector, because it does not register as a “file system”.  Of course, these network redirectors work fine, whether they register as file systems or not, because the only other use the OS has for registered file system is to mount media volumes

又是OSR的！
另外能否把联接给出，因为我们看不到图

http://www.osr.com\\ntinsider\\2000\\fs_filter\\fs_filter.htm [url] [/url]