Subject: Re: [linux-next][bock] [bisected c20cfc27a] WARNING: CPU: 22 PID: 0 at block/blk-core.c:2655 .blk_update_request+0x4f8/0x500

From: Abdul Haleem <[email-masked]>
Date: Thu, 11 May 2017 15:22:25 +0530

On Wed, 2017-05-10 at 19:55 +0200, Christoph Hellwig wrote:
> Hi Abdul,
> 
> can you test the patch below?  I'll try to create a way to inject
> short WRITE SAME commands using qemu next, but I thought I'd give
> you a chance to try it as well.

No warnings with the patch. Thanks for all your support !

Reported-and-tested-by : Abdul Haleem <[email-masked]>

> 
> ---
> diff --git a/block/blk-core.c b/block/blk-core.c
> index c580b0138a7f..c7068520794b 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -2644,8 +2644,6 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
>  		return false;
>  	}
> 
> -	WARN_ON_ONCE(req->rq_flags & RQF_SPECIAL_PAYLOAD);
> -
>  	req->__data_len -= total_bytes;
> 
>  	/* update sector only for requests with clear definition of sector */
> @@ -2658,17 +2656,19 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
>  		req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
>  	}
> 
> -	/*
> -	 * If total number of sectors is less than the first segment
> -	 * size, something has gone terribly wrong.
> -	 */
> -	if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
> -		blk_dump_rq_flags(req, "request botched");
> -		req->__data_len = blk_rq_cur_bytes(req);
> -	}
> +	if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
> +		/*
> +		 * If total number of sectors is less than the first segment
> +		 * size, something has gone terribly wrong.
> +		 */
> +		if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
> +			blk_dump_rq_flags(req, "request botched");
> +			req->__data_len = blk_rq_cur_bytes(req);
> +		}
> 
> -	/* recalculate the number of segments */
> -	blk_recalc_rq_segments(req);
> +		/* recalculate the number of segments */
> +		blk_recalc_rq_segments(req);
> +	}
> 
>  	return true;
>  }
> 

-- 
Regard's

Abdul Haleem
IBM Linux Technology Centre