From: Keir Fraser <keir.fraser@citrix.com>
Date: Sun, 16 Aug 2009 07:42:29 +0000 (+0100)
Subject: Revert 927:56df01ffed10
X-Git-Tag: xen-3.4.2~13
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=24fb05dc7638346a98464046ae5959f4efc257c4;p=legacy%2Flinux-2.6.18-xen.git

Revert 927:56df01ffed10
---

diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index eed6a9e2..78311e32 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -200,16 +200,6 @@ static void print_stats(blkif_t *blkif)
 	blkif->st_oo_req = 0;
 }
 
-static void refill_credit(blkif_t *blkif)
-{
-	blkif->credit_time = jiffies + msecs_to_jiffies(blkif->credit_msec);
-	blkif->available_credit += blkif->credit_req;
-
-	/* this allows for bursting. */
-	if (blkif->available_credit > (blkif->credit_req * blkif->credit_msec))
-		blkif->available_credit = blkif->credit_req;
-}
-
 int blkif_schedule(void *arg)
 {
 	blkif_t *blkif = arg;
@@ -237,9 +227,6 @@ int blkif_schedule(void *arg)
 			blkif->waiting_reqs = 1;
 		unplug_queue(blkif);
 
-		if (time_after(jiffies, blkif->credit_time))
-			refill_credit(blkif);
-
 		if (log_stats && time_after(jiffies, blkif->st_print))
 			print_stats(blkif);
 	}
@@ -326,23 +313,11 @@ static int do_block_io_op(blkif_t *blkif)
 	rp = blk_rings->common.sring->req_prod;
 	rmb(); /* Ensure we see queued requests up to 'rp'. */
 
-	/* if there's no available request credit right now, and limiting
-	 * is requested, then don't bother with going any further.
-	 */
-	if (blkif->remaining_credit <= 0 && blkif->credit_req != 0)
-		return (rc != rp) ? 1 : 0;
-
 	while (rc != rp) {
 
 		if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
 			break;
 
-		/* FIXME: Should we report QoS overages as VBD_OO, or not? */
-		if (blkif->credit_req != 0 && --blkif->remaining_credit <= 0) {
-			more_to_do = 1;
-			break;
-		}
-
 		if (kthread_should_stop()) {
 			more_to_do = 1;
 			break;
diff --git a/drivers/xen/blkback/common.h b/drivers/xen/blkback/common.h
index c6cd00b4..6dff5e76 100644
--- a/drivers/xen/blkback/common.h
+++ b/drivers/xen/blkback/common.h
@@ -96,11 +96,6 @@ typedef struct blkif_st {
 
 	grant_handle_t shmem_handle;
 	grant_ref_t    shmem_ref;
-
-	int		    credit_req;
-	int		    remaining_credit;
-	int		    credit_msec;
-	unsigned long	    credit_time;
 } blkif_t;
 
 blkif_t *blkif_alloc(domid_t domid);
diff --git a/drivers/xen/blkback/xenbus.c b/drivers/xen/blkback/xenbus.c
index f43dfe1c..7e689c75 100644
--- a/drivers/xen/blkback/xenbus.c
+++ b/drivers/xen/blkback/xenbus.c
@@ -255,42 +255,6 @@ fail:
 	return err;
 }
 
-static void blkback_read_credit(struct xenbus_transaction xbt,
-				struct xenbus_device *dev,
-                                unsigned long *credit, unsigned long *msec)
-{
-	char *s, *e;
-	unsigned long b, u;
-	char *ratestr;
-
-	/* Default to unlimited I/O operations. */
-	*credit = ~0UL;
-	*usec = 0;
-
-	ratestr = xenbus_read(xbt, dev->nodename, "credit", NULL);
-	if (IS_ERR(ratestr))
-		return;
-
-	s = ratestr;
-	b = simple_strtoul(s, &e, 10);
-	if ((s == e) || (*e != ','))
-		goto fail;
-
-	s = e + 1;
-	u = simple_strtoul(s, &e, 10);
-	if ((s == e) || (*e != '\0'))
-		goto fail;
-
-	*credit = b;
-	*msec = (u / 1000);
-
-	kfree(ratestr);
-	return;
-
- fail:
-	WPRINTK("Failed to parse I/O credit limit. I/O operations are unlimited.\n");
-	kfree(ratestr);
-}
 
 /**
  * Callback received when the hotplug scripts have placed the physical-device
@@ -437,7 +401,6 @@ static void frontend_changed(struct xenbus_device *dev,
 /* ** Connection ** */
 
 
-
 /**
  * Write the physical details regarding the block device to the store, and
  * switch to Connected state.
@@ -462,10 +425,6 @@ again:
 	if (err)
 		goto abort;
 
-	blkback_read_credit(xbt, dev, &be->blkif->credit_req,
-			    &be->blkif->credit_msec);
-	be->blkif->remaining_credit = be->blkif->credit_req;
-
 	err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
 			    vbd_size(&be->blkif->vbd));
 	if (err) {