[Sheepdog] [PATCH 1/3] collie: read objects directly in parse_objs()

[MORITA Kazutaka]

When we send read requests without a SD_FLAG_CMD_DIRECT flag, Sheepdog
checks data consistency of the target objects before forwarding them.
However, fixing consistency could cause updating, so it is not safe
for collie to send non-direct read requests because running VMs could
update the objects at the same time.

This patch calculates the target nodes in parse_objs(), and send read
requests directly to them.  This also improves performance of vdi
listing because we can avoid a redundant consistency check.

Signed-off-by: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
---
 collie/collie.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/collie/collie.c b/collie/collie.c
index 6db5a08..493d492 100644
--- a/collie/collie.c
+++ b/collie/collie.c
@@ -269,34 +269,50 @@ static int parse_vdi(vdi_parser_func_t func, void *data)
 		close(fd);
 		return ret;
 	}
+	close(fd);
 
 	for (nr = 0; nr < SD_NR_VDIS; nr++) {
 		struct sd_obj_req hdr;
 		struct sd_obj_rsp *rsp = (struct sd_obj_rsp *)&hdr;
+		uint64_t oid;
+		int n;
+		char name[128];
 
 		if (!test_bit(nr, vdi_inuse))
 			continue;
 
+		oid = vid_to_vdi_oid(nr);
+		n = obj_to_sheep(node_list_entries, nr_nodes, oid, 0);
+		addr_to_str(name, sizeof(name), node_list_entries[n].addr, 0);
+
+		fd = connect_to(name, node_list_entries[n].port);
+		if (fd < 0) {
+			printf("failed to connect %s:%d\n", name,
+			       node_list_entries[n].port);
+			continue;
+		}
+
 		wlen = 0;
 		rlen = sizeof(i);
 
 		memset(&hdr, 0, sizeof(hdr));
 		hdr.opcode = SD_OP_READ_OBJ;
-		hdr.oid = vid_to_vdi_oid(nr);
+		hdr.oid = oid;
 		hdr.data_length = rlen;
+		hdr.flags = SD_FLAG_CMD_DIRECT;
+		hdr.epoch = node_list_version;
 
 		ret = exec_req(fd, (struct sd_req *)&hdr, &i, &wlen, &rlen);
+		close(fd);
 
 		if (!ret && rsp->result == SD_RES_SUCCESS) {
 			if (i.name[0] == '\0') /* deleted */
 				continue;
 			func(i.vdi_id, i.name, i.snap_id, 0, &i, data);
 		} else
-			printf("error %lu, %d\n", nr, ret);
+			printf("error %lu, %d, %x\n", nr, ret, rsp->result);
 	}
 
-	close(fd);
-
 	return 0;
 }
 
-- 
1.5.6.5