kern/115572: ata disk bug

[Graham]

The following reply was made to PR kern/115572; it has been noted by GNATS.

From: Graham <gbradley at rocketmail.com>
To: "Søren" Schmidt <sos at deepcore.dk>
Cc: bug-followup at FreeBSD.org, Poul-Henning Kamp <phk at phk.freebsd.dk>
Subject: Re: kern/115572: ata disk bug
Date: Sun, 19 Aug 2007 13:03:21 -0700 (PDT)

 thanks Søren....
 
 --- Søren Schmidt <sos at deepcore.dk> wrote:
 
 > Poul-Henning Kamp wrote:
 > > In message <200708182120.l7ILKBvF046099 at freefall.freebsd.org>,
 > Graham writes:
 > >
 > >   
 > >> 2. attempt (say)....
 > >> rabbit# dd if=/dev/zero of=/dev/ad4s1 oseek=2097151 count=1 bs=64k
 > >> and the result is....
 > >> dd: /dev/ad4s1: Input/output error
 > >> 1+0 records in
 > >> 0+0 records out
 > >> 0 bytes transferred in 0.000325 secs (0 bytes/sec)
 > >>
 > >> (If dd is performed on the raw drive, /dev/ad4 then block boundary
 > is
 > >> always a power of 2, and blocksize a smaller power of 2.  That's
 > always
 > >> ok.  But we can't assume we use drives that way.)
 > >>
 > >> So a transfer which starts in the 28-bit zone, but extends over
 > into
 > >> the 48-bit region, fails.  Such transfers happen in the superblock
 > of
 > >> certain size drives, and that plays havoc.  The sector mapping of
 > gbde
 > >> can do this, but soft-update gets screwed by this happening.  It's
 > not
 > >> actually to do with the crypto as I first suspected.
 > >>     
 > >
 > > This is a problem in the ata disk driver.
 > >   
 > Yeah, the crossover point from using 28bit to 48bit addressing is 
 > flawed, below patch should fix that:
 > 
 > --- ata-all.c   23 Feb 2007 16:25:08 -0000      1.279
 > +++ ata-all.c   19 Aug 2007 09:25:58 -0000
 > @@ -738,7 +738,7 @@
 >  
 >      atadev->flags &= ~ATA_D_48BIT_ACTIVE;
 >  
 > -    if ((request->u.ata.lba >= ATA_MAX_28BIT_LBA ||
 > +    if (((request->u.ata.lba + request->u.ata.count) >= 
 > ATA_MAX_28BIT_LBA ||
 >          request->u.ata.count > 256) &&
 >         atadev->param.support.command2 & ATA_SUPPORT_ADDRESS48) {
 >  
 > 
 > 
 > -Søren
 > >
 > >
 > >   
 > 
 > 
 > 
 I have compiled with this patch and done an (admittedly superficial)
 test and the bug is not now visible.  I am quite happy to see this one
 marked as solved.  My apologies to P-H.K. for starting off on the wrong
 tack.
 
 Do I need to flag anyone else for this to get taken up in the stock
 kernel, or will this happen automatic now?
 
 regards
 Graham
 
 
 
        
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