USB Disk Filter driver can't see read/write activity

Discussion in 'Windows Vista Drivers' started by alan, Aug 2, 2003.

  1. alan

    alan Guest

    I'm a newbie to Windows driver writing. To start learning
    I have a filter driver that is to simply put an entry into
    the Application log whenever an IRP passes through it,
    then passes the IRP on. This is on Windows 2000 using a
    removable USB disk (Linksys 32 MB 'solid state' instant
    disk device).

    My filter is installed as an Upper Filter to usbstor.sys.
    When I attach the USB disk, my filter sees the DriverEntry
    call, the AddDevice call, and sees IRP_MN_START_DEVICE,
    properly placing an entry in the log. Also sees some more
    IRPs that I have not specifically identified, but simply
    have noted in the log as having been passed on. All of
    these happen before I have tried to access anything on the
    USB disk.

    When I access the disk, the filter sees no IRP activity.
    I would have thought I'd see some IRPs pass through during
    disk reading/writing. Reading/writing of the disk is
    successful. The filter next sees IRPs when I remove the

    So, given the successful disk reads/writes and the lack of
    IRP activity detected by the filter during these
    operations the filter must be bypassed by the reads and

    What part of the picture am I missing here, and how do I
    get my filter to see the read/write related IRPs? Is
    there some part(s) of the DDK that I should review more
    thoroughly to understand this? .. Or is it somewhere else
    I should read? If the filter is indeed being bypassed by
    reads/writes is this behavior strictly related to USB
    (i.e. usbstor.sys) or is this a common part of port and/or
    class driver operation?

    Thanks for any help.
    alan, Aug 2, 2003
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