Re: [PATCH] DAC960_Release bug (2.4.x)

[John v/d Kamp]

The libhd can be found here:
ftp://ftp.suse.com/pub/suse/i386/8.1/suse/src/hwinfo-5.39-2.src.rpm
We use a somewhat older version, but that probably doesn't matter.

I've compiled the module, and our install software ran just fine.
Repartitioning the drive was no problem. Using the driver on a normal
system was no problem either (never was).

--
John van der Kamp, ConnecTUX

On Thu, 17 Apr 2003, Dave Olien wrote:

>
> I've been looking over the kernel's code paths that call a block driver's
> release method.  In linux 2.4 and 2.5, it looks like nowhere does the
> kernel EVER call the release method with a non-NULL file descriptor.
> The file pointer argument to the release method seems to be a left-over
> from linux 2.2.
>
> I think the DAC960_Open and DAC960_Release methods in 2.4 and 2.5
> are more broken than it first appears.
>
> The SPECIAL file descriptor that you get with O_NONBLOCK
> is a BAD idea.  But we're probably stuck because applications use it.
> Could you pass me a URL to the libhd library you're using?  I'd like
> to look it over.  What behavior does it expect with the O_NBLOCK flag?
>
> I think what I'll do is assert that there can be ONLY ONE such SPECIAL
> file descriptor open at a time.  At Open time, we'll save a pointer to
> the inode for this special file descriptor in a module-local variable.
> If at open time, we discover there is already such an open file descriptor,
> we'll refuse to open another one.
>
> In the release function, we'll compare the inode pointer passed in with
> the saved inode pointer, and do the SPECIAL close case, and then zero
> out the saved inode pointer.  This isn't a completely reliable solution.
> But, it's the best I think of for now.
>
> A patch for 2.4 is attached at the end of this mail.  I'd appreciate it if
> you could give it a try and let me know how it works.
>