On Wed, 28 Aug 2013 14:29:05 +0800 Shaohua Li <shli@xxxxxxxxxx> wrote:
> 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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Applied, thanks.
NeilBrown
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