[Qemu-devel] [PATCH 1/2] nbd: Handle fixed new-style clients.

[Hani Benhabiles <kroosec@gmail.com>]

Signed-off-by: Hani Benhabiles <hani@linux.com>
---
 include/block/nbd.h |  6 ++++++
 nbd.c               | 12 +++++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 79502a0..95d52ab 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -45,6 +45,12 @@ struct nbd_reply {
 #define NBD_FLAG_ROTATIONAL     (1 << 4)        /* Use elevator algorithm - rotational media */
 #define NBD_FLAG_SEND_TRIM      (1 << 5)        /* Send TRIM (discard) */
 
+/* New-style global flags. */
+#define NBD_FLAG_FIXED_NEWSTYLE     (1 << 0)    /* Fixed newstyle protocol. */
+
+/* New-style client flags. */
+#define NBD_FLAG_C_FIXED_NEWSTYLE   (1 << 0)    /* Fixed newstyle protocol. */
+
 #define NBD_CMD_MASK_COMMAND	0x0000ffff
 #define NBD_CMD_FLAG_FUA	(1 << 16)
 
diff --git a/nbd.c b/nbd.c
index e5084b6..fb0a9cf 100644
--- a/nbd.c
+++ b/nbd.c
@@ -224,7 +224,7 @@ static int nbd_receive_options(NBDClient *client)
     int rc;
 
     /* Client sends:
-        [ 0 ..   3]   reserved (0)
+        [ 0 ..   3]   client flags
         [ 4 ..  11]   NBD_OPTS_MAGIC
         [12 ..  15]   NBD_OPT_EXPORT_NAME
         [16 ..  19]   length
@@ -236,9 +236,10 @@ static int nbd_receive_options(NBDClient *client)
         LOG("read failed");
         goto fail;
     }
-    TRACE("Checking reserved");
-    if (tmp != 0) {
-        LOG("Bad reserved received");
+    TRACE("Checking client flags");
+    tmp = be32_to_cpu(tmp);
+    if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
+        LOG("Bad client flags received");
         goto fail;
     }
 
@@ -246,7 +247,7 @@ static int nbd_receive_options(NBDClient *client)
         LOG("read failed");
         goto fail;
     }
-    TRACE("Checking reserved");
+    TRACE("Checking opts magic");
     if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
         LOG("Bad magic received");
         goto fail;
@@ -333,6 +334,7 @@ static int nbd_send_negotiate(NBDClient *client)
         cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
     } else {
         cpu_to_be64w((uint64_t*)(buf + 8), NBD_OPTS_MAGIC);
+        cpu_to_be16w((uint16_t *)(buf + 16), NBD_FLAG_FIXED_NEWSTYLE);
     }
 
     if (client->exp) {
-- 
1.8.3.2