nbd: Remove nbd_co_flush() wrapper function

The only thing nbd_co_flush() does is call nbd_client_co_flush(). Just
use that function directly in the BlockDriver definitions and remove the
wrapper.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230504115750.54437-10-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/nbd.c

@@ -1920,11 +1920,6 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
     return ret;
 }
 
-static int coroutine_fn nbd_co_flush(BlockDriverState *bs)
-{
-    return nbd_client_co_flush(bs);
-}
-
 static void nbd_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
@@ -2120,7 +2115,7 @@ static BlockDriver bdrv_nbd = {
     .bdrv_co_pwritev            = nbd_client_co_pwritev,
     .bdrv_co_pwrite_zeroes      = nbd_client_co_pwrite_zeroes,
     .bdrv_close                 = nbd_close,
-    .bdrv_co_flush_to_os        = nbd_co_flush,
+    .bdrv_co_flush_to_os        = nbd_client_co_flush,
     .bdrv_co_pdiscard           = nbd_client_co_pdiscard,
     .bdrv_refresh_limits        = nbd_refresh_limits,
     .bdrv_co_truncate           = nbd_co_truncate,
@@ -2148,7 +2143,7 @@ static BlockDriver bdrv_nbd_tcp = {
     .bdrv_co_pwritev            = nbd_client_co_pwritev,
     .bdrv_co_pwrite_zeroes      = nbd_client_co_pwrite_zeroes,
     .bdrv_close                 = nbd_close,
-    .bdrv_co_flush_to_os        = nbd_co_flush,
+    .bdrv_co_flush_to_os        = nbd_client_co_flush,
     .bdrv_co_pdiscard           = nbd_client_co_pdiscard,
     .bdrv_refresh_limits        = nbd_refresh_limits,
     .bdrv_co_truncate           = nbd_co_truncate,
@@ -2176,7 +2171,7 @@ static BlockDriver bdrv_nbd_unix = {
     .bdrv_co_pwritev            = nbd_client_co_pwritev,
     .bdrv_co_pwrite_zeroes      = nbd_client_co_pwrite_zeroes,
     .bdrv_close                 = nbd_close,
-    .bdrv_co_flush_to_os        = nbd_co_flush,
+    .bdrv_co_flush_to_os        = nbd_client_co_flush,
     .bdrv_co_pdiscard           = nbd_client_co_pdiscard,
     .bdrv_refresh_limits        = nbd_refresh_limits,
     .bdrv_co_truncate           = nbd_co_truncate,