On Wed, Aug 28, 2013 at 01:41:50PM +1000, NeilBrown wrote:
>
> > +struct llist_node *llist_reverse_order(struct llist_node *head)
> > +{
> > + struct llist_node *second, *third;
> > +
> > + if (head == NULL || head->next == NULL)
> > + return head;
> > + second = head->next;
> > + head->next = NULL;
> > +
> > + do {
> > + third = second->next;
> > + second->next = head;
> > +
> > + head = second;
> > + second = third;
> > + } while (second);
> > +
> > + return head;
> > +}
> > +EXPORT_SYMBOL_GPL(llist_reverse_order);
>
> This is somewhat longer that necessary.
>
> struct llist_node *llist_reverse_order(struct llist_node *head)
> {
> struct llist_node *new_head = NULL;
>
> while (head) {
> struct llist_node *tmp = head;
> head = head->next;
> tmp->next = new_head;
> new_head = tmp;
> }
>
> return new_head;
> }
>
> I think that is short enough to just open-code in the top of
> release_stripe_list.
>
> Are you OK with that?
It's ok. Other patches can still apply with hunks.
Subject: raid5: fix stripe release order
patch "make release_stripe lockless" changes the order stripes are released.
Originally I thought block layer can take care of request merge, but it appears
there are still some requests not merged. It's easy to fix the order.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
drivers/md/raid5.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
Index: linux/drivers/md/raid5.c
===================================================================
--- linux.orig/drivers/md/raid5.c 2013-08-28 13:51:39.586914255 +0800
+++ linux/drivers/md/raid5.c 2013-08-28 13:53:25.429582150 +0800
@@ -239,6 +239,20 @@ static void __release_stripe(struct r5co
do_release_stripe(conf, sh);
}
+static struct llist_node *llist_reverse_order(struct llist_node *head)
+{
+ struct llist_node *new_head = NULL;
+
+ while (head) {
+ struct llist_node *tmp = head;
+ head = head->next;
+ tmp->next = new_head;
+ new_head = tmp;
+ }
+
+ return new_head;
+}
+
/* should hold conf->device_lock already */
static int release_stripe_list(struct r5conf *conf)
{
@@ -247,6 +261,7 @@ static int release_stripe_list(struct r5
struct llist_node *head;
head = llist_del_all(&conf->released_stripes);
+ head = llist_reverse_order(head);
while (head) {
sh = llist_entry(head, struct stripe_head, release_list);
head = llist_next(head);
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