Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken

[erich]

Dear Randy.Dunlap,

If it is true, I will add sg count check in arcmsr.
Driver report : host->sg_tablesize=ARCMSR_MAX_SG_ENTRIES to linux scsi host 
layer.
But got an incorrect request of sg list count from .queuecommand.
Could you tell me which value of ARCMSR_MAX_XFER_SECTORS (4096/512)?

Best Regards
Erich chen

----- Original Message ----- 
From: "Randy.Dunlap" <rdunlap@xxxxxxxxxxxx>
To: "erich" <erich@xxxxxxxxxxxx>
Cc: <axboe@xxxxxxx>; <dax@xxxxxxxxxxxx>; <billion.wu@xxxxxxxxxxxx>; 
<viro@xxxxxxxxxxxxxxxx>; <akpm@xxxxxxxx>; <matti.aarnio@xxxxxxxxxxx>; 
<linux-kernel@xxxxxxxxxxxxxxx>; <James.Bottomley@xxxxxxxxxxxx>; 
<ccaputo@xxxxxxx>
Sent: Thursday, April 20, 2006 11:38 PM
Subject: Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken


> On Thu, 20 Apr 2006 16:11:04 +0800 erich wrote:
>
> > Dear Dear Jens Axboe,
> >
> > Thanks for your notification and advice.
> > Areca's firmware has max sg entries of 38 limit.
> > In my debug driver I had add this condition check.
> > But no one request more than 38 sg.
>
> Yesterday I saw a request with 70 sg pieces.  It was while
> running mkfs.ext3 .
>
> > Both transfer length all have a lot of requests equal with 38 sg.
> > But why it ocur only at 4096 sectors?
> > If the /sys/block/sda/queue/max_sectors_kb equal 256 all operation 
> > running
> > well.
> > But if I modify it more than 256, the bug appeared.
> > I  will do more research about why there were a lot of requests equal 
> > with
> > 38 sg in all file system.
> > And only it ocur at the volume that format with mkfs.ext2.
> > Thanks again.
> >
> > Best Regards
> > Erich Chen
> >
> > ----- Original Message ----- 
> > From: "Jens Axboe" <axboe@xxxxxxx>
> > To: "erich" <erich@xxxxxxxxxxxx>
> > Cc: <dax@xxxxxxxxxxxx>; <billion.wu@xxxxxxxxxxxx>; "Al Viro"
> > <viro@xxxxxxxxxxxxxxxx>; "Andrew Morton" <akpm@xxxxxxxx>; "Randy.Dunlap"
> > <rdunlap@xxxxxxxxxxxx>; "Matti Aarnio" <matti.aarnio@xxxxxxxxxxx>;
> > <linux-kernel@xxxxxxxxxxxxxxx>; "James Bottomley"
> > <James.Bottomley@xxxxxxxxxxxx>; "Chris Caputo" <ccaputo@xxxxxxx>
> > Sent: Thursday, April 20, 2006 2:42 PM
> > Subject: Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken
> >
> >
> > > On Thu, Apr 20 2006, erich wrote:
> > >> Dear Jens Axboe,
> > >>
> > >> I  do "fsck -fy /dev/sda1" on driver MAX_XFER_SECTORS 512.
> > >> The file system was not clean.
> > >> I attach mesg.txt for you refer to.
> > >>
> > >> =====================================
> > >> == boot with driver MAX_XFER_SECTORS 4096
> > >> =====================================
> > >> #mkfs.ext2 /dev/sda1
> > >> #reboot
> > >> =====================================
> > >> == boot with driver MAX_XFER_SECTORS 512
> > >> =====================================
> > >> #fsck -fy /dev/sda1
> > >> /dev/sda1:clean,.............
> > >> #reboot
> > >> =====================================
> > >> == boot with driver MAX_XFER_SECTORS 4096
> > >> =====================================
> > >> #mount /dev/sda1 /mnt/sda1
> > >> #cp /root/aa /mnt/sda1
> > >> #reboot
> > >> =====================================
> > >> == boot with driver MAX_XFER_SECTORS 512
> > >> =====================================
> > >> #fsck -fy /dev/sda1
> > >> /dev/sda1: no clean,........and dump message such as the attach file
> > >> mesg.txt.
> > >
> > > So the conclusion is that your driver and/or hardware corrupts data 
> > > when
> > > you set MAX_XFER_SECTORS too high. I can't help you anymore with this,
> > > you should be in the best position to debug the driver and/or hardware
> > > :-)
> > >
> > > It could be that the higher setting just exposes another transfer
> > > setting bug, like maximum number of segments or segment size, etc.
> > >
> > > -- 
> > > Jens Axboe
> > >
>
>
> ---
> ~Randy 

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