libata: reimplement link iterator

Implement __ata_port_next_link() and reimplement
__ata_port_for_each_link() and ata_port_for_each_link() using it.
This removes relatively large inlined code and makes iteration easier
to extend.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index ffd622f..3eaca34 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1265,34 +1265,17 @@
 	return ata_tag_valid(link->active_tag) || link->sactive;
 }
 
-static inline struct ata_link *ata_port_first_link(struct ata_port *ap)
-{
-	if (sata_pmp_attached(ap))
-		return ap->pmp_link;
-	return &ap->link;
-}
+extern struct ata_link *__ata_port_next_link(struct ata_port *ap,
+					     struct ata_link *link,
+					     bool dev_only);
 
-static inline struct ata_link *ata_port_next_link(struct ata_link *link)
-{
-	struct ata_port *ap = link->ap;
-
-	if (ata_is_host_link(link)) {
-		if (!sata_pmp_attached(ap))
-			return NULL;
-		return ap->pmp_link;
-	}
-
-	if (++link < ap->nr_pmp_links + ap->pmp_link)
-		return link;
-	return NULL;
-}
-
-#define __ata_port_for_each_link(lk, ap) \
-	for ((lk) = &(ap)->link; (lk); (lk) = ata_port_next_link(lk))
+#define __ata_port_for_each_link(link, ap) \
+	for ((link) = __ata_port_next_link((ap), NULL, false); (link); \
+	     (link) = __ata_port_next_link((ap), (link), false))
 
 #define ata_port_for_each_link(link, ap) \
-	for ((link) = ata_port_first_link(ap); (link); \
-	     (link) = ata_port_next_link(link))
+	for ((link) = __ata_port_next_link((ap), NULL, true); (link); \
+	     (link) = __ata_port_next_link((ap), (link), true))
 
 #define ata_link_for_each_dev(dev, link) \
 	for ((dev) = (link)->device; \