Re: 2.6.14-mm1

[Reuben Farrelly <reuben-lkml@reub.net>]

Hi,

On 9/11/2005 3:21 a.m., James Bottomley wrote:
> On Mon, 2005-11-07 at 10:52 -0800, Andrew Morton wrote:
>> sd_issue_flush() has been altered to run scsi_disk_get_from_dev(), which
>> takes a semaphore.  It does this from within spinlock and, as we see here,
>> from within softirq.
>>
>> Methinks the people who developed and tested that patch forgot to enable
>> CONFIG_PREEMPT, CONFIG_DEBUG_KERNEL, CONFIG_DEBUG_SLAB,
>> CONFIG_DEBUG_SPINLOCK and CONFIG_DEBUG_SPINLOCK_SLEEP.
> 
> Actually, I do too (as far as I can on non-x86).  I assume you also need
> a filesystem that excites this, though.
> 
> Try the attached: We can probably rely on the block device having opened
> the sd device, so there should already be a reference held on the
> scsi_disk ... well that's my theory and I'm sticking to it.
> 
> James
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -769,20 +769,16 @@ static void sd_end_flush(request_queue_t
>  static int sd_prepare_flush(request_queue_t *q, struct request *rq)
>  {
>  	struct scsi_device *sdev = q->queuedata;
> -	struct scsi_disk *sdkp = scsi_disk_get_from_dev(&sdev->sdev_gendev);
> -	int ret = 0;
> +	struct scsi_disk *sdkp = dev_get_drvdata(&sdev->sdev_gendev);
>  
> -	if (sdkp) {
> -		if (sdkp->WCE) {
> -			memset(rq->cmd, 0, sizeof(rq->cmd));
> -			rq->flags |= REQ_BLOCK_PC | REQ_SOFTBARRIER;
> -			rq->timeout = SD_TIMEOUT;
> -			rq->cmd[0] = SYNCHRONIZE_CACHE;
> -			ret = 1;
> -		}
> -		scsi_disk_put(sdkp);
> -	}
> -	return ret;
> +	if (!sdkp || !sdkp->WCE)
> +		return 0;
> +
> +	memset(rq->cmd, 0, sizeof(rq->cmd));
> +	rq->flags |= REQ_BLOCK_PC | REQ_SOFTBARRIER;
> +	rq->timeout = SD_TIMEOUT;
> +	rq->cmd[0] = SYNCHRONIZE_CACHE;
> +	return 1;
>  }
>  
>  static void sd_rescan(struct device *dev)

Yup, with that patch it all works now.  Thanks James!

FWIW, the filesystem on the raid md's is a reiserfs (reiserfs v3 that is).

reuben