[Qemu-devel] [PATCH 3/3] nbd: Improve debug traces on little-endian

[Eric Blake <eblake@redhat.com>]

Print debug tracing messages while data is still in native
ordering, rather than after we've potentially swapped it into
network order for transmission.  Also, it's nice if the server
mentions what it is replying, to correlate it to with what the
client says it is receiving.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 nbd/client.c | 8 ++++----
 nbd/server.c | 5 +++--
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/nbd/client.c b/nbd/client.c
index 6f0541d..602768e 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -629,16 +629,16 @@ ssize_t nbd_send_request(QIOChannel *ioc, struct nbd_request *request)
     uint8_t buf[NBD_REQUEST_SIZE];
     ssize_t ret;

+    TRACE("Sending request to server: "
+          "{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}",
+          request->from, request->len, request->handle, request->type);
+
     cpu_to_be32w((uint32_t*)buf, NBD_REQUEST_MAGIC);
     cpu_to_be32w((uint32_t*)(buf + 4), request->type);
     cpu_to_be64w((uint64_t*)(buf + 8), request->handle);
     cpu_to_be64w((uint64_t*)(buf + 16), request->from);
     cpu_to_be32w((uint32_t*)(buf + 24), request->len);

-    TRACE("Sending request to server: "
-          "{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}",
-          request->from, request->len, request->handle, request->type);
-
     ret = write_sync(ioc, buf, sizeof(buf));
     if (ret < 0) {
         return ret;
diff --git a/nbd/server.c b/nbd/server.c
index 98e3957..6d9c15a 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -656,6 +656,9 @@ static ssize_t nbd_send_reply(QIOChannel *ioc, struct nbd_reply *reply)

     reply->error = system_errno_to_nbd_errno(reply->error);

+    TRACE("Sending response to client: { .error = %d, handle = %" PRIu64 " }",
+          reply->error, reply->handle);
+
     /* Reply
        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
        [ 4 ..  7]    error   (0 == no error)
@@ -665,8 +668,6 @@ static ssize_t nbd_send_reply(QIOChannel *ioc, struct nbd_reply *reply)
     stl_be_p(buf + 4, reply->error);
     stq_be_p(buf + 8, reply->handle);

-    TRACE("Sending response to client");
-
     ret = write_sync(ioc, buf, sizeof(buf));
     if (ret < 0) {
         return ret;
-- 
2.5.5