[PATCH] block: add global timeout to requests

[James Bottomley <James.Bottomley@HansenPartnership.com>]

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@HansenPartnership.com>

---

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);