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Re: kern/38643: [dM] st tape drive loses data
The following reply was made to PR kern/38643; it has been noted by GNATS.
From: David Holland <dholland-bugs%netbsd.org@localhost>
To: Havard Eidnes <he%NetBSD.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost, mouse%Rodents.Montreal.QC.CA@localhost,
Subject: Re: kern/38643: [dM] st tape drive loses data
Date: Mon, 1 Sep 2008 18:41:36 +0000
On Mon, Sep 01, 2008 at 08:06:58PM +0200, Havard Eidnes wrote:
> I don't have any suggestions for a fix, but I may have an
> observation (which I'm sure you've thought of yourself as well,
> but it's good to have it written down anyway).
I think I've found the problem, and if so this is the fix:
RCS file: /cvsroot/src/sys/dev/scsipi/st.c,v
retrieving revision 1.205
diff -u -p -r1.205 st.c
--- st.c 8 Jun 2008 18:18:34 -0000 1.205
+++ st.c 1 Sep 2008 18:24:12 -0000
@@ -1125,7 +1125,7 @@ done:
* Correctly set the buf to indicate a completed xfer
- bp->b_resid = bp->b_bcount;
+ bp->b_resid = 0;
This has been this way ~forever, and AFAIK it's always been wrong, but
changes in kern_physio before 4.0 have changed the resulting behavior
so that it could easily be consistent with the observed phenomena.
There's also another maybe related issue: line 413 of kern_physio.c
/* uio->uio_offset = ps->ps_endoffset; */
which yamt added, commented out, when cleaning up some grossness prior
to 4.0. I am pretty sure it's why part of the data is getting skipped
over, and I think it should be uncommented. yamt?
On the other hand, I could be completely wrong here too...
David A. Holland
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