On Wed, Mar 18 2009, James Bottomley wrote:
> We can eliminate the SCSI command timed out check entirely if the block
> layer does this for us. The way to do this in block is to check how
> long the request has been outstanding if a requeue is requested and
> ending it if we've gone over retries * timeout.
>
> This will also eliminate many cases in SCSI where we evade the command
> timeout for various reasons (like initial success converted to requeue)
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
>
> ---
>
> Index: linux-2.6/block/blk-core.c
> ===================================================================
> --- linux-2.6.orig/block/blk-core.c 2009-02-19 16:42:00.140427205 -0500
> +++ linux-2.6/block/blk-core.c 2009-03-18 10:36:10.511526815 -0400
> @@ -937,6 +937,8 @@ EXPORT_SYMBOL(blk_start_queueing);
> */
> void blk_requeue_request(struct request_queue *q, struct request *rq)
> {
> + unsigned long wait_for = (rq->retries + 1) * rq->timeout;
> +
> blk_delete_timer(rq);
> blk_clear_rq_complete(rq);
> trace_block_rq_requeue(q, rq);
> @@ -944,7 +946,13 @@ void blk_requeue_request(struct request_
> if (blk_rq_tagged(rq))
> blk_queue_end_tag(q, rq);
>
> - elv_requeue_request(q, rq);
> + if (time_before(rq->start_time + wait_for, jiffies)) {
> + printk(KERN_ERR "%s: timing out command, waited %lus\n",
> + rq->rq_disk ? rq->rq_disk->disk_name : "?",
> + wait_for/HZ);
> + blk_end_request(rq, -EIO, blk_rq_bytes(rq));
> + } else
> + elv_requeue_request(q, rq);
> }
> EXPORT_SYMBOL(blk_requeue_request);
Applied, though I think a
time_after(jiffies, time)
is usually much clearer, since we are checking for an expired event (not
an early one) :-)
--
Jens Axboe
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