Re: [PATCH] xfs/194: fix the exception when run on 4k sector drives

[Dave Chinner <david@fromorbit.com>]

On Tue, Aug 18, 2015 at 10:24:59PM -0400, Zirong Lang wrote:
> 
> 
> ----- 原始邮件 -----
> > 发件人: "Dave Chinner" <david@fromorbit.com>
> > 收件人: "Zorro Lang" <zlang@redhat.com>
> > 抄送: fstests@vger.kernel.org, sandeen@redhat.com
> > 发送时间: 星期三, 2015年 8 月 19日 上午 6:28:32
> > 主题: Re: [PATCH] xfs/194: fix the exception when run on 4k sector drives
> > 
> > On Wed, Aug 19, 2015 at 01:21:51AM +0800, Zorro Lang wrote:
> > > The below command in "Test 4":
> > > 
> > >     xfs_io -c "pwrite -S 0x33 -b 512 `expr $blksize \* 2` 512"
> > > 
> > > will run failed on 4k sector drives. So I use min_alignment size
> > > to replace the hard-code 512.
> > > 
> > > Also I make sure the blksize won't less than min_alignment size,
> > > after blksize=`expr $pgsize / 8`.
> > > 
> > > If blksize really less than min_alignment size, I set blksize =
> > > min_alignment size, and for sure the consistency of test result,
> > > I repair pgsize(already not real page size) number according to
> > > the new blksize.
> > > 
> > > Because IRIX can't use _min_dio_alignment(), so remove it from
> > > supported os list.
> > 
> > Not true - that's what the 'feature -s' branch in
> > _min_dio_alignment() is supposed to be for. Just add another check
> > for "$HOSTOS" == "Linux"....
> 
> Do you mean change _min_dio_alignment() to:
> _min_dio_alignment()
> {
>     dev=$1
> 
>     if [ -b "$dev" -a $HOSTOS" == "Linux" ]; then
>         blockdev --getss $dev
>     else
>         $here/src/feature -s
>     fi
> }

Yes.

> I really don't understand why page size will be the minimum dio alignment?
> Do you mean in other OS(except linux), the sector size = page size?

No. It means that on other platforms the page size will be used as
alignment restrictions. If those platforms need anything different,
then they can add a similar 'elif [ "$HOSTOS" == "foo" ];' branch in
there to call the appropriate function. You don't need to worry
about that.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com