Re: block: re-add discard_granularity and alignment checks

[Jens Axboe]

On 10/28/2015 06:23 AM, Ming Lin wrote:
> On Thu, Oct 22, 2015 at 10:03 AM, Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
> > On Thu, Oct 22 2015 at 12:59pm -0400,
> > Ming Lin <mlin@xxxxxxxxxx> wrote:
> >
> > > From: Ming Lin <ming.l@xxxxxxxxxxxxxxx>
> > >
> > > In commit b49a087("block: remove split code in
> > > blkdev_issue_{discard,write_same}"), discard_granularity and alignment
> > > checks were removed. Ideally, with bio late splitting, the upper layers
> > > shouldn't need to depend on device's limits.
> > >
> > > Christoph reported a discard regression on the HGST Ultrastar SN100 NVMe
> > > device when mkfs.xfs. We have not found the root cause yet.
> > >
> > > This patch re-adds discard_granularity and alignment checks by reverting
> > > the related changes in commit b49a087. The good thing is now we can
> > > remove the 2G discard size cap and just use UINT_MAX to avoid bi_size
> > > overflow.
> > >
> > > Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> > > Tested-by: Christoph Hellwig <hch@xxxxxx>
> > > Signed-off-by: Ming Lin <ming.l@xxxxxxxxxxxxxxx>
> >
> > Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
>
> Hi Jens,
>
> Would you please take this one?

I was going to add it for 4.3, but hch just pointed out that it's a 
regression in this series. I'll send it in for 4.3.

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/