[sheepdog] [PATCH] add list_move and list_move_tail

[Christoph Hellwig]

And use them to optimize list_del/list_add_(tail) pairs.

Signed-off-by: Christoph Hellwig <hch at lst.de>

Index: sheepdog/include/list.h
===================================================================
--- sheepdog.orig/include/list.h	2012-05-28 11:12:30.728363536 +0200
+++ sheepdog/include/list.h	2012-05-28 12:39:31.612497218 +0200
@@ -80,6 +80,11 @@ static inline void __list_del(struct lis
 	prev->next = next;
 }
 
+static inline void __list_del_entry(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+}
+
 static inline void list_del(struct list_head *entry)
 {
 	__list_del(entry->prev, entry->next);
@@ -88,10 +93,23 @@ static inline void list_del(struct list_
 
 static inline void list_del_init(struct list_head *entry)
 {
-	__list_del(entry->prev, entry->next);
+	__list_del_entry(entry);
 	INIT_LIST_HEAD(entry);
 }
 
+static inline void list_move(struct list_head *list, struct list_head *head)
+{
+	__list_del_entry(list);
+	list_add(list, head);
+}
+
+static inline void list_move_tail(struct list_head *list,
+		struct list_head *head)
+{
+	__list_del_entry(list);
+	list_add_tail(list, head);
+}
+
 static inline void __list_splice(const struct list_head *list,
 				 struct list_head *prev,
 				 struct list_head *next)
diff --git a/collie/treeview.c b/collie/treeview.c
index b1d2242..29d265b 100644
--- a/collie/treeview.c
+++ b/collie/treeview.c
@@ -98,10 +98,8 @@ static void compaction(struct vdi_tree *parent)
 
 	list_for_each_entry_safe(vdi, e, &parent->children, siblings) {
 		new_parent = find_vdi(root, vdi->pvid, vdi->name);
-		if (new_parent && parent != new_parent) {
-			list_del(&vdi->siblings);
-			list_add_tail(&vdi->siblings, &new_parent->children);
-		}
+		if (new_parent && parent != new_parent)
+			list_move_tail(&vdi->siblings, &new_parent->children);
 
 		compaction(vdi);
 	}
diff --git a/sheep/recovery.c b/sheep/recovery.c
index 3fb34c0..f7bc62c 100644
--- a/sheep/recovery.c
+++ b/sheep/recovery.c
@@ -417,10 +417,8 @@ static void resume_wait_recovery_requests(void)
 	list_for_each_entry_safe(req, t, &sys->wait_rw_queue,
 				 request_list) {
 		dprintf("resume wait oid %" PRIx64 "\n", req->local_oid);
-		if (req->rp.result == SD_RES_OBJ_RECOVERING) {
-			list_del(&req->request_list);
-			list_add_tail(&req->request_list, &sys->request_queue);
-		}
+		if (req->rp.result == SD_RES_OBJ_RECOVERING)
+			list_move_tail(&req->request_list, &sys->request_queue);
 	}
 
 	process_request_event_queues();
diff --git a/sheep/sdnet.c b/sheep/sdnet.c
index f4408f7..7fcff4b 100644
--- a/sheep/sdnet.c
+++ b/sheep/sdnet.c
@@ -65,8 +65,7 @@ static void check_object_consistency(struct sd_req *hdr)
 		nr_bmaps++;
 		if (bmap->vdi_id == vdi_id) {
 			set_bit(data_oid_to_idx(hdr->obj.oid), bmap->dobjs);
-			list_del(&bmap->list);
-			list_add_tail(&bmap->list, &sys->consistent_obj_list);
+			list_move_tail(&bmap->list, &sys->consistent_obj_list);
 			return;
 		}
 	}
@@ -267,8 +266,7 @@ void resume_wait_epoch_requests(void)
 			setup_access_to_local_objects(req);
 		/* peer retries the request locally when its epoch changes. */
 		case SD_RES_NEW_NODE_VER:
-			list_del(&req->request_list);
-			list_add_tail(&req->request_list, &sys->request_queue);
+			list_move_tail(&req->request_list, &sys->request_queue);
 			break;
 		default:
 			break;
@@ -287,8 +285,7 @@ void resume_wait_obj_requests(uint64_t oid)
 		 * recovered, notify the pending request. */
 		if (req->local_oid == oid) {
 			dprintf("retry %" PRIx64 "\n", req->local_oid);
-			list_del(&req->request_list);
-			list_add_tail(&req->request_list, &sys->request_queue);
+			list_move_tail(&req->request_list, &sys->request_queue);
 		}
 	}
 	process_request_event_queues();