Re: [PATCH block#for-2.6.31] block: fix an oops on BLKPREP_KILL

[Jens Axboe <jens.axboe@oracle.com>]

On Fri, May 29 2009, James Bottomley wrote:
> Doing a bit of torture testing, I ran across a BUG in the block
> subsystem (at blk-core.c:2048): the test for if the request is queued.
> 
> It turns out the trigger was a BLKPREP_KILL coming out of the SCSI prep
> function.  Currently for BLKPREP_KILL requests, we send them straight
> into __blk_end_request_all() with an error, but they've never been
> dequeued, so they trip the bug.  Fix this by starting requests before
> killing them.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> 
> ---
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 8b3b74e..9a0568c 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1789,6 +1789,7 @@ struct request *blk_peek_request(struct request_queue *q)
>  			break;
>  		} else if (ret == BLKPREP_KILL) {
>  			rq->cmd_flags |= REQ_QUIET;
> +			blk_start_request(rq);
>  			__blk_end_request_all(rq, -EIO);
>  		} else {
>  			printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);

Given how illogical that now looks, I think it could do with a comment.
I'll add that while applying.

-- 
Jens Axboe