Re: [PATCH V5] block: make segment size limit workable for > 4K PAGE_SIZE

[Ming Lei <ming.lei@redhat.com>]

On Wed, Feb 26, 2025 at 09:38:36AM -0800, Bart Van Assche wrote:
> On 2/24/25 6:21 PM, Ming Lei wrote:
> > diff --git a/block/blk.h b/block/blk.h
> > index 90fa5f28ccab..9cf9a0099416 100644
> > --- a/block/blk.h
> > +++ b/block/blk.h
> > @@ -14,6 +14,7 @@
> >   struct elevator_type;
> >   #define	BLK_DEV_MAX_SECTORS	(LLONG_MAX >> 9)
> > +#define	BLK_MIN_SEGMENT_SIZE	4096
> >   /* Max future timer expiry for timeouts */
> >   #define BLK_MAX_TIMEOUT		(5 * HZ)
> 
> Hi Ming,
> 
> Would you agree with reducing BLK_MIN_SEGMENT_SIZE further, e.g. to 2048
> or 1024? Although I'm not aware of any storage devices that need this

We never take < 4096 as min segment size, I'd rather not relax it for
avoiding any potential regression.

But if any kind of real device requires it, we may re-consider to relax
it more.

> change, this change would make it possible to test the new code paths
> introduced by this patch on systems with a 4 KiB page size. I wrote
> blktests tests for the new code paths before I posted my patch series
> "Support limits below the page size"
> (https://lore.kernel.org/linux-block/20230612203314.17820-1-bvanassche@acm.org/).
> The last two patches of that patch series are still needed to run these
> blktests tests.

Indeed, I guess you will re-send the two, and I am glad to review after it is
posed out.



thanks,
Ming