diff --git a/dog/cluster.c b/dog/cluster.c
index 169e837b2..dbdc92ea6 100644
--- a/dog/cluster.c
+++ b/dog/cluster.c
@@ -281,19 +281,15 @@ static int list_snapshot(int argc, char **argv)
 	return ret;
 }
 
-static void fill_cb(void *data, enum btree_node_type type, void *arg)
+static void fill_cb(struct sd_index *idx, void *arg, int ignore)
 {
-	struct sd_index *ext;
 	struct sd_inode *inode = (struct sd_inode *)arg;
 	uint64_t oid;
 
-	if (type == BTREE_INDEX) {
-		ext = (struct sd_index *)data;
-		if (ext->vdi_id) {
-			oid = vid_to_data_oid(ext->vdi_id, ext->idx);
-			object_tree_insert(oid, inode->nr_copies,
-					   inode->copy_policy);
-		}
+	if (idx->vdi_id) {
+		oid = vid_to_data_oid(idx->vdi_id, idx->idx);
+		object_tree_insert(oid, inode->nr_copies,
+				   inode->copy_policy);
 	}
 }
 
@@ -323,7 +319,7 @@ static void fill_object_tree(uint32_t vid, const char *name, const char *tag,
 			object_tree_insert(oid, i->nr_copies, i->copy_policy);
 		}
 	} else
-		traverse_btree(i, fill_cb, &i);
+		sd_inode_index_walk(i, fill_cb, &i);
 
 	/* fill vmstate object id */
 	nr_vmstate_object = DIV_ROUND_UP(i->vm_state_size, SD_DATA_OBJ_SIZE);
diff --git a/dog/vdi.c b/dog/vdi.c
index 3cc623999..debed0a31 100644
--- a/dog/vdi.c
+++ b/dog/vdi.c
@@ -1786,21 +1786,17 @@ struct check_arg {
 	int nr_copies;
 };
 
-static void check_cb(void *data, enum btree_node_type type, void *arg)
+static void check_cb(struct sd_index *idx, void *arg, int ignore)
 {
-	struct sd_index *ext;
 	struct check_arg *carg = arg;
 	uint64_t oid;
 
-	if (type == BTREE_INDEX) {
-		ext = (struct sd_index *)data;
-		if (ext->vdi_id) {
-			oid = vid_to_data_oid(ext->vdi_id, ext->idx);
-			*(carg->done) = (uint64_t)ext->idx * SD_DATA_OBJ_SIZE;
-			vdi_show_progress(*(carg->done), carg->inode->vdi_size);
-			queue_vdi_check_work(carg->inode, oid, NULL, carg->wq,
-					     carg->nr_copies);
-		}
+	if (idx->vdi_id) {
+		oid = vid_to_data_oid(idx->vdi_id, idx->idx);
+		*(carg->done) = (uint64_t)idx->idx * SD_DATA_OBJ_SIZE;
+		vdi_show_progress(*(carg->done), carg->inode->vdi_size);
+		queue_vdi_check_work(carg->inode, oid, NULL, carg->wq,
+				     carg->nr_copies);
 	}
 }
 
@@ -1841,7 +1837,7 @@ int do_vdi_check(const struct sd_inode *inode)
 		}
 	} else {
 		struct check_arg arg = {inode, &done, wq, nr_copies};
-		traverse_btree(inode, check_cb, &arg);
+		sd_inode_index_walk(inode, check_cb, &arg);
 		vdi_show_progress(inode->vdi_size, inode->vdi_size);
 	}
 
diff --git a/include/sheepdog_proto.h b/include/sheepdog_proto.h
index 9746fccac..1d17e8fab 100644
--- a/include/sheepdog_proto.h
+++ b/include/sheepdog_proto.h
@@ -249,11 +249,9 @@ struct sd_index_header {
 	uint32_t entries;
 };
 
-enum btree_node_type {
-	BTREE_HEAD = 1,
-	BTREE_INDEX,
-	BTREE_INDIRECT_IDX,
-};
+#define	BTREE_HEAD         1
+#define	BTREE_INDEX        2
+#define BTREE_INDIRECT_IDX 4
 
 typedef int (*write_node_fn)(uint64_t id, void *mem, unsigned int len,
 				uint64_t offset, uint32_t flags, int copies,
@@ -287,9 +285,8 @@ extern void sd_inode_copy_vdis(write_node_fn writer, read_node_fn reader,
 			       uint8_t nr_copies, uint8_t copy_policy,
 			       struct sd_inode *newi);
 
-typedef void (*btree_cb_fn)(void *data, enum btree_node_type type, void *arg);
-extern void traverse_btree(const struct sd_inode *inode,
-			   btree_cb_fn fn, void *arg);
+typedef void (*index_cb_fn)(struct sd_index *, void *arg, int type);
+void sd_inode_index_walk(const struct sd_inode *inode, index_cb_fn, void *);
 
 /* 64 bit FNV-1a non-zero initial basis */
 #define FNV1A_64_INIT ((uint64_t) 0xcbf29ce484222325ULL)
diff --git a/lib/sd_inode.c b/lib/sd_inode.c
index 444e3d719..5056843ec 100644
--- a/lib/sd_inode.c
+++ b/lib/sd_inode.c
@@ -126,27 +126,36 @@ static int indirect_idx_compare(struct sd_indirect_idx *a,
 	return intcmp(a->idx, b->idx);
 }
 
+typedef void (*btree_cb_fn)(void *data, void *arg, int type);
+
 /*
- * traverse the whole btree that include all the inode->data_vdi_id, bnode,
- * data objects and call btree_cb_fn()
+ * Traverse the whole btree that include all header, indirect_idx and index.
+ * @interest specify which objects user wants to run @fn against.
+ *
+ * If error happens when reading btree internal nodes, we simply continue to
+ * process next candidate.
  */
-void traverse_btree(const struct sd_inode *inode, btree_cb_fn fn, void *arg)
+static void traverse_btree(const struct sd_inode *inode, btree_cb_fn fn,
+			   void *arg, int interest)
 {
 	struct sd_index_header *header = INDEX_HEADER(inode->data_vdi_id);
 	struct sd_index_header *leaf_node = NULL;
 	struct sd_index *last, *iter;
 	struct sd_indirect_idx *last_idx, *iter_idx;
 	void *tmp;
+	int ret;
 
-	fn(header, BTREE_HEAD, arg);
+	if (interest & BTREE_HEAD)
+		fn(header, arg, BTREE_HEAD);
 	if (header->depth == 1) {
 		last = LAST_INDEX(inode->data_vdi_id);
 		iter = FIRST_INDEX(inode->data_vdi_id);
 
-		while (iter != last) {
-			fn(iter, BTREE_INDEX, arg);
-			iter++;
-		}
+		if (interest & BTREE_INDEX)
+			while (iter != last) {
+				fn(iter, arg, BTREE_INDEX);
+				iter++;
+			}
 	} else if (header->depth == 2) {
 		last_idx = LAST_INDRECT_IDX(inode->data_vdi_id);
 		iter_idx = FIRST_INDIRECT_IDX(inode->data_vdi_id);
@@ -154,17 +163,25 @@ void traverse_btree(const struct sd_inode *inode, btree_cb_fn fn, void *arg)
 		tmp = (void *)leaf_node;
 
 		while (iter_idx != last_idx) {
-			inode_actor.reader(iter_idx->oid, &tmp,
-					   SD_INODE_DATA_INDEX_SIZE, 0);
+			ret = inode_actor.reader(iter_idx->oid, &tmp,
+						 SD_INODE_DATA_INDEX_SIZE, 0);
+			if (ret != SD_RES_SUCCESS) {
+				sd_err("failed to read %"PRIx64, iter_idx->oid);
+				iter_idx++;
+				continue;
+			}
 
-			fn(iter_idx, BTREE_INDIRECT_IDX, arg);
-			fn(leaf_node, BTREE_HEAD, arg);
+			if (interest & BTREE_INDIRECT_IDX)
+				fn(iter_idx, arg, BTREE_INDIRECT_IDX);
+			if (interest & BTREE_HEAD)
+				fn(leaf_node, arg, BTREE_HEAD);
 			last = LAST_INDEX(leaf_node);
 			iter = FIRST_INDEX(leaf_node);
-			while (iter != last) {
-				fn(iter, BTREE_INDEX, arg);
-				iter++;
-			}
+			if (interest & BTREE_INDEX)
+				while (iter != last) {
+					fn(iter, arg, BTREE_INDEX);
+					iter++;
+				}
 			iter_idx++;
 		}
 
@@ -173,8 +190,15 @@ void traverse_btree(const struct sd_inode *inode, btree_cb_fn fn, void *arg)
 		panic("This B-tree not support depth %u", header->depth);
 }
 
+/* Walk the sd_inode's vdi index array and call func against each sd_index */
+void sd_inode_index_walk(const struct sd_inode *inode, index_cb_fn func,
+			 void *arg)
+{
+	traverse_btree(inode, (btree_cb_fn)func, arg, BTREE_INDEX);
+}
+
 #ifdef DEBUG
-static void dump_cb(void *data, enum btree_node_type type, void *arg)
+static void dump_cb(void *data, void *arg, int type)
 {
 	struct sd_index_header *header;
 	struct sd_index *ext;
@@ -203,7 +227,8 @@ static void dump_btree(struct sd_inode *inode)
 {
 #ifdef DEBUG
 	sd_info("btree> BEGIN");
-	traverse_btree(inode, dump_cb, NULL);
+	traverse_btree(inode, dump_cb, NULL,
+		       BTREE_INDEX | BTREE_HEAD | BTREE_INDIRECT_IDX);
 	sd_info("btree> END");
 #endif
 }
@@ -840,27 +865,24 @@ struct stat_arg {
 	uint32_t vid;
 };
 
-static void stat_cb(void *data, enum btree_node_type type, void *arg)
+static void stat_cb(struct sd_index *idx, void *arg,
+		    int ignore)
 {
-	struct sd_index *ext;
 	struct stat_arg *sarg = arg;
 	uint64_t *my = sarg->my;
 	uint64_t *cow = sarg->cow;
 
-	if (type == BTREE_INDEX) {
-		ext = (struct sd_index *)data;
-		if (ext->vdi_id == sarg->vid)
-			(*my)++;
-		else if (ext->vdi_id != 0)
-			(*cow)++;
-	}
+	if (idx->vdi_id == sarg->vid)
+		(*my)++;
+	else if (idx->vdi_id != 0)
+		(*cow)++;
 }
 
 static void hypver_volume_stat(const struct sd_inode *inode,
 			       uint64_t *my_objs, uint64_t *cow_objs)
 {
 	struct stat_arg arg = {my_objs, cow_objs, inode->vdi_id};
-	traverse_btree(inode, stat_cb, &arg);
+	sd_inode_index_walk(inode, stat_cb, &arg);
 }
 
 static void volume_stat(const struct sd_inode *inode, uint64_t *my_objs,
diff --git a/sheep/http/kv.c b/sheep/http/kv.c
index fa7d13adb..482174119 100644
--- a/sheep/http/kv.c
+++ b/sheep/http/kv.c
@@ -90,34 +90,30 @@ int kv_create_account(const char *account)
 	return sd_create_hyper_volume(account, &vdi_id);
 }
 
-static void bucket_iterater(void *data, enum btree_node_type type, void *arg)
+static void bucket_iterater(struct sd_index *idx, void *arg, int ignore)
 {
-	struct sd_index *ext;
 	struct bucket_iterater_arg *biarg = arg;
 	struct kv_bnode bnode;
 	uint64_t oid;
 	int ret;
 
-	if (type == BTREE_INDEX) {
-		ext = (struct sd_index *)data;
-		if (!ext->vdi_id)
-			return;
+	if (!idx->vdi_id)
+		return;
 
-		oid = vid_to_data_oid(ext->vdi_id, ext->idx);
-		ret = sd_read_object(oid, (char *)&bnode, sizeof(bnode), 0);
-		if (ret != SD_RES_SUCCESS) {
-			sd_err("Failed to read data object %"PRIx64, oid);
-			return;
-		}
-
-		if (bnode.name[0] == 0)
-			return;
-		if (biarg->cb)
-			biarg->cb(bnode.name, biarg->opaque);
-		biarg->bucket_count++;
-		biarg->object_count += bnode.object_count;
-		biarg->bytes_used += bnode.bytes_used;
+	oid = vid_to_data_oid(idx->vdi_id, idx->idx);
+	ret = sd_read_object(oid, (char *)&bnode, sizeof(bnode), 0);
+	if (ret != SD_RES_SUCCESS) {
+		sd_err("Failed to read data object %"PRIx64, oid);
+		return;
 	}
+
+	if (bnode.name[0] == 0)
+		return;
+	if (biarg->cb)
+		biarg->cb(bnode.name, biarg->opaque);
+	biarg->bucket_count++;
+	biarg->object_count += bnode.object_count;
+	biarg->bytes_used += bnode.bytes_used;
 }
 
 static int read_account_meta(const char *account, uint64_t *bucket_count,
@@ -141,7 +137,7 @@ static int read_account_meta(const char *account, uint64_t *bucket_count,
 		goto out;
 	}
 
-	traverse_btree(inode, bucket_iterater, &arg);
+	sd_inode_index_walk(inode, bucket_iterater, &arg);
 	*object_count = arg.object_count;
 	*bucket_count = arg.bucket_count;
 	*used = arg.bytes_used;
@@ -253,7 +249,7 @@ static int bnode_create(struct kv_bnode *bnode, uint32_t account_vid)
 	int ret;
 
 	ret = sd_read_object(vid_to_vdi_oid(account_vid), (char *)inode,
-			       sizeof(*inode), 0);
+			     sizeof(*inode), 0);
 	if (ret != SD_RES_SUCCESS) {
 		sd_err("failed to read %" PRIx32 " %s", account_vid,
 		       sd_strerror(ret));
@@ -430,33 +426,29 @@ struct object_iterater_arg {
 	uint32_t count;
 };
 
-static void object_iterater(void *data, enum btree_node_type type, void *arg)
+static void object_iterater(struct sd_index *idx, void *arg, int ignore)
 {
-	struct sd_index *ext;
 	struct object_iterater_arg *oiarg = arg;
 	struct kv_onode *onode = NULL;
 	uint64_t oid;
 	int ret;
 
-	if (type == BTREE_INDEX) {
-		ext = (struct sd_index *)data;
-		if (!ext->vdi_id)
-			goto out;
-
-		onode = xmalloc(SD_DATA_OBJ_SIZE);
-		oid = vid_to_data_oid(ext->vdi_id, ext->idx);
-		ret = sd_read_object(oid, (char *)onode, SD_DATA_OBJ_SIZE, 0);
-		if (ret != SD_RES_SUCCESS) {
-			sd_err("Failed to read data object %"PRIx64, oid);
-			goto out;
-		}
+	if (!idx->vdi_id)
+		goto out;
 
-		if (onode->name[0] == '\0')
-			goto out;
-		if (oiarg->cb)
-			oiarg->cb(onode->name, oiarg->opaque);
-		oiarg->count++;
+	onode = xmalloc(SD_DATA_OBJ_SIZE);
+	oid = vid_to_data_oid(idx->vdi_id, idx->idx);
+	ret = sd_read_object(oid, (char *)onode, SD_DATA_OBJ_SIZE, 0);
+	if (ret != SD_RES_SUCCESS) {
+		sd_err("Failed to read data object %"PRIx64, oid);
+		goto out;
 	}
+
+	if (onode->name[0] == '\0')
+		goto out;
+	if (oiarg->cb)
+		oiarg->cb(onode->name, oiarg->opaque);
+	oiarg->count++;
 out:
 	free(onode);
 }
@@ -476,7 +468,7 @@ static int bucket_iterate_object(uint32_t bucket_vid, object_iter_cb cb,
 		goto out;
 	}
 
-	traverse_btree(inode, object_iterater, &arg);
+	sd_inode_index_walk(inode, object_iterater, &arg);
 out:
 	free(inode);
 	return ret;
@@ -590,7 +582,7 @@ int kv_iterate_bucket(const char *account, bucket_iter_cb cb, void *opaque)
 		goto out;
 	}
 
-	traverse_btree(&account_inode, bucket_iterater, &arg);
+	sd_inode_index_walk(&account_inode, bucket_iterater, &arg);
 out:
 	sys->cdrv->unlock(account_vid);
 	return ret;
diff --git a/sheep/vdi.c b/sheep/vdi.c
index ac1fa905f..7af743e95 100644
--- a/sheep/vdi.c
+++ b/sheep/vdi.c
@@ -824,20 +824,15 @@ struct delete_arg {
 	uint32_t *nr_deleted;
 };
 
-static void delete_cb(void *data, enum btree_node_type type, void *arg)
+static void delete_cb(struct sd_index *idx, void *arg, int ignore)
 {
-	struct sd_index *ext;
 	struct delete_arg *darg = (struct delete_arg *)arg;
 	uint64_t oid;
 	int ret;
 
-	if (type != BTREE_INDEX)
-		return;
-
-	ext = (struct sd_index *)data;
-	if (ext->vdi_id) {
-		oid = vid_to_data_oid(ext->vdi_id, ext->idx);
-		if (ext->vdi_id != darg->inode->vdi_id)
+	if (idx->vdi_id) {
+		oid = vid_to_data_oid(idx->vdi_id, idx->idx);
+		if (idx->vdi_id != darg->inode->vdi_id)
 			sd_debug("object %" PRIx64 " is base's data, would"
 				 " not be deleted.", oid);
 		else {
@@ -900,7 +895,7 @@ static int delete_one_vdi(uint32_t vdi_id)
 		}
 	} else {
 		struct delete_arg arg = {inode, &nr_deleted};
-		traverse_btree(inode, delete_cb, &arg);
+		sd_inode_index_walk(inode, delete_cb, &arg);
 	}
 
 	if (vdi_is_deleted(inode))