On Wed, 2008-12-17 at 09:06 +0100, Jens Axboe wrote:
> On Tue, Dec 16 2008, 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)
> >
> > James
> >
> > ---
> >
> > diff --git a/block/blk-core.c b/block/blk-core.c
> > index c36aa98..d32af31 100644
> > --- a/block/blk-core.c
> > +++ b/block/blk-core.c
> > @@ -926,6 +926,8 @@ 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);
> > blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
> > @@ -933,7 +935,17 @@ void blk_requeue_request(struct request_queue *q, struct request *rq)
> > 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)) {
>
> I prefer time_after(), reads better.
>
> > + int bytes = (rq->hard_nr_sectors << 9);
> > +
> > + printk(KERN_ERR "%s: timing out command, waited %lus\n",
> > + rq->rq_disk ? rq->rq_disk->disk_name : "?",
> > + wait_for/HZ);
> > + if (blk_pc_request(rq))
> > + bytes = rq->data_len;
> > + blk_end_request(rq, -EIO, bytes);
>
> You can just do
>
> blk_end_request(rq, -EIO, blk_rq_bytes(rq));
>
> and get rid of the 'bytes' variable and type check.
>
> > + } else
> > + elv_requeue_request(q, rq);
> > }
> > EXPORT_SYMBOL(blk_requeue_request);
>
> But I agree with the patch. Will you rediff, or shall I just apply with
> the suggest changes?
I'll rediff ... we're going to have to test it out quite a bit,
especially when I pull the SCSI timeout stuff.
James
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