nbd: add support for NBD_CMD_FLUSH

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/nbd.c b/nbd.c
index c597d47..4fd0f4e 100644
--- a/nbd.c
+++ b/nbd.c
@@ -203,7 +203,8 @@ int nbd_negotiate(int csock, off_t size, uint32_t flags)
     cpu_to_be64w((uint64_t*)(buf + 8), 0x00420281861253LL);
     cpu_to_be64w((uint64_t*)(buf + 16), size);
     cpu_to_be32w((uint32_t*)(buf + 24),
-                 flags | NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_FUA);
+                 flags | NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_FLUSH |
+                 NBD_FLAG_SEND_FUA);
     memset(buf + 28, 0, 124);
 
     if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
@@ -710,6 +711,18 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset,
         TRACE("Request type is DISCONNECT");
         errno = 0;
         return 1;
+    case NBD_CMD_FLUSH:
+        TRACE("Request type is FLUSH");
+
+        ret = bdrv_flush(bs);
+        if (ret < 0) {
+            LOG("flush failed");
+            reply.error = -ret;
+        }
+
+        if (nbd_send_reply(csock, &reply) == -1)
+            return -1;
+        break;
     default:
         LOG("invalid request type (%u) received", request.type);
         errno = EINVAL;