Re: 2.6.27-rc1 (2fca5c): libata: kernel cant boot

["Dave Young" <hidave.darkstar@gmail.com>]

On Fri, Oct 24, 2008 at 3:24 PM, Jens Axboe <jens.axboe@oracle.com> wrote:
> On Fri, Oct 24 2008, Paul Mundt wrote:
>> On Fri, Oct 24, 2008 at 09:13:29AM +0200, Jens Axboe wrote:
>> > On Fri, Oct 24 2008, Jens Axboe wrote:
>> > > On Fri, Oct 24 2008, Alexander Beregalov wrote:
>> > > > Hi
>> > > >
>> > > > commit 2fca5ccf97d2c28bcfce44f5b07d85e74e3cd18e
>> > > > Author: Jens Axboe <jens.axboe@oracle.com>
>> > > > Date:   Wed Oct 22 09:34:49 2008 +0200
>> > > >
>> > > >     libata: switch to using block layer tagging support
>> > > >
>> > > >
>> > > > This kernel can not read even 0 sector on disk with rootfs. It
>> > > > initialized disk, but cant read it at all.
>> > > >  CMD646 on Sparc
>> > > >
>> > > > Rverting helped.
>> > >
>> > > Doh, how annoying! What driver does that controller use? PATA doesn't
>> > > even use NCQ, so it's a bit of an oddity that it makes a difference at
>> > > all.
>> > >
>> > > Can you provide the boot messages?
>> >
>> > Darn, this smells like a train wreck. I'm assuming this fixes it?
>> >
>> Yes, that fixes it.

To confirm: 2.6.28-rc1 ata-piix, fixed for me as well.

>
> OK, that's pretty bad. 2.6.28-rc1 will not work on any box using libata
> with non-ncq disks. If you need me, I'll be at the bar.
>
> ----------
>
> From e598055dde1951c47c8b3522616f6ebff0ed9847 Mon Sep 17 00:00:00 2001
> From: Jens Axboe <jens.axboe@oracle.com>
> Date: Fri, 24 Oct 2008 09:22:42 +0200
> Subject: [PATCH] libata: fix bug with non-ncq devices
>
> The recent commit 201f1b98822078c808b5e2d379a6ddbfc0a06ee1 to enable
> support for block layer tagging in libata was broken for non-NCQ
> devices. The block layer initializes the tag field to -1 to detect
> invalid uses of a tag, and if the libata devices does NOT support
> NCQ, we just used that field to index the internal command list.
> So we need to check for -1 first and only use the tag field if
> it's valid.
>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> ---
>  drivers/ata/libata-scsi.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index d5b9b72..4b95c43 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -708,7 +708,11 @@ static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
>  {
>        struct ata_queued_cmd *qc;
>
> -       qc = ata_qc_new_init(dev, cmd->request->tag);
> +       if (cmd->request->tag != -1)
> +               qc = ata_qc_new_init(dev, cmd->request->tag);
> +       else
> +               qc = ata_qc_new_init(dev, 0);
> +
>        if (qc) {
>                qc->scsicmd = cmd;
>                qc->scsidone = done;
> --
> 1.6.0.2.588.g3102
>
>
> --
> Jens Axboe
>
> --
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-- 
Regards
dave