Re: [PATCH 8/8] block: stop calling blk_queue_bounce for passthrough requests

[Guenter Roeck <linux@roeck-us.net>]

On 4/9/21 12:40 AM, Christoph Hellwig wrote:
> On Thu, Apr 08, 2021 at 02:45:06PM -0700, Guenter Roeck wrote:
>> On Wed, Mar 31, 2021 at 09:30:01AM +0200, Christoph Hellwig wrote:
>>> Instead of overloading the passthrough fast path with the deprecated
>>> block layer bounce buffering let the users that combine an old
>>> undermaintained driver with a highmem system pay the price by always
>>> falling back to copies in that case.
>>>
>>
>> Hmm, that price is pretty high. When trying to boot sh images from usb,
>> it results in a traceback, followed by an i/o error, and the drive
>> fails to open.
> 
> That's just because this warning is completely bogus, sorry.
> 
> Does this patch fix the boot for you?
> 

Yes it does.

Tested-by: Guenter Roeck <linux@roeck-us.net>

Thanks,
Guenter

> diff --git a/block/blk-map.c b/block/blk-map.c
> index dac78376acc899..3743158ddaeb76 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -485,9 +485,6 @@ int blk_rq_append_bio(struct request *rq, struct bio *bio)
>  	struct bio_vec bv;
>  	unsigned int nr_segs = 0;
>  
> -	if (WARN_ON_ONCE(rq->q->limits.bounce != BLK_BOUNCE_NONE))
> -		return -EINVAL;
> -
>  	bio_for_each_bvec(bv, bio, iter)
>  		nr_segs++;
>  
>