[sheepdog] [PATCH v2] sheep: fix a bug that read_object() fail in recovery

[levin li]

From: levin li <xingke.lwp at taobao.com>

read_object() calls forward_read_obj_req() to get the object,
but may fail with result SD_RES_OLD_NODE_VER, read_object() do
nothing to handle this error, this patch fixed this problem
by sending a gateway request to local node, making gateway to
retry when error occur.

Signed-off-by: levin li <xingke.lwp at taobao.com>
---
 sheep/store.c |   47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/sheep/store.c b/sheep/store.c
index 52c4716..aae322b 100644
--- a/sheep/store.c
+++ b/sheep/store.c
@@ -558,9 +558,11 @@ int read_object(struct vnode_info *vnodes, uint32_t epoch,
 		uint64_t oid, char *data, unsigned int datalen,
 		uint64_t offset, int nr_copies)
 {
-	struct request read_req;
-	struct sd_req *hdr = &read_req.rq;
-	int ret;
+	struct sd_req hdr;
+	struct sd_rsp *rsp = (struct sd_rsp *)&hdr;
+	char host[128];
+	unsigned int wlen = 0, rlen = datalen;
+	int fd, ret;
 
 	if (sys->enable_write_cache && object_is_cached(oid)) {
 		ret = object_cache_read(oid, data, datalen, offset,
@@ -572,23 +574,36 @@ int read_object(struct vnode_info *vnodes, uint32_t epoch,
 		}
 		return ret;
 	}
-	memset(&read_req, 0, sizeof(read_req));
+
 forward_read:
-	hdr->opcode = SD_OP_READ_OBJ;
-	hdr->data_length = datalen;
-	hdr->epoch = epoch;
+	addr_to_str(host, sizeof(host), sys->this_node.addr, 0);
+	fd = connect_to(host, sys->this_node.port);
+	if (fd < 0) {
+		dprintf("Failed to connect to local node\n");
+		return SD_RES_EIO;
+	}
 
-	hdr->obj.oid = oid;
-	hdr->obj.offset = offset;
-	hdr->obj.copies = nr_copies;
+	hdr.opcode = SD_OP_READ_OBJ;
+	hdr.data_length = datalen;
+	hdr.epoch = epoch;
 
-	read_req.data = data;
-	read_req.op = get_sd_op(hdr->opcode);
-	read_req.vnodes = vnodes;
+	hdr.obj.oid = oid;
+	hdr.obj.offset = offset;
+	hdr.obj.copies = nr_copies;
 
-	ret = forward_read_obj_req(&read_req);
-	if (ret != SD_RES_SUCCESS)
-		eprintf("failed to forward read object %x\n", ret);
+	ret = exec_req(fd, &hdr, data, &wlen, &rlen);
+	close(fd);
+
+	if (ret) {
+		dprintf("Failed to read object %" PRIx64 "\n", oid);
+		return SD_RES_EIO;
+	}
+
+	if (rsp->result != SD_RES_SUCCESS) {
+		dprintf("Failed to read object %" PRIx64 " %s\n", oid,
+			sd_strerror(rsp->result));
+		return rsp->result;
+	}
 
 	return ret;
 }
-- 
1.7.10