block: do not check bdrv_file_open

The set of BlockDrivers that have .bdrv_file_open coincides with those
that have .protocol_name and guess what---checking drv->bdrv_file_open
is done to see if the driver is a protocol.  So check drv->protocol_name
instead.

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

block.c

@@ -926,7 +926,6 @@ BlockDriver *bdrv_find_protocol(const char *filename,
     int i;
 
     GLOBAL_STATE_CODE();
-    /* TODO Drivers without bdrv_file_open must be specified explicitly */
 
     /*
      * XXX(hch): we really should not let host device detection
@@ -1983,7 +1982,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
     open_flags = bdrv_open_flags(bs, bs->open_flags);
     node_name = qemu_opt_get(opts, "node-name");
 
-    assert(!drv->bdrv_file_open || file == NULL);
+    assert(!drv->protocol_name || file == NULL);
     ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
     if (ret < 0) {
         goto fail_opts;
@@ -2084,7 +2083,7 @@ static int bdrv_fill_options(QDict **options, const char *filename,
         }
         /* If the user has explicitly specified the driver, this choice should
          * override the BDRV_O_PROTOCOL flag */
-        protocol = drv->bdrv_file_open;
+        protocol = drv->protocol_name;
     }
 
     if (protocol) {
@@ -4123,7 +4122,7 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
     }
 
     /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
-    assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
+    assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->protocol_name);
     /* file must be NULL if a protocol BDS is about to be created
      * (the inverse results in an error message from bdrv_open_common()) */
     assert(!(flags & BDRV_O_PROTOCOL) || !file);
@@ -5971,7 +5970,7 @@ int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs)
         return drv->bdrv_co_get_allocated_file_size(bs);
     }
 
-    if (drv->bdrv_file_open) {
+    if (drv->protocol_name) {
         /*
          * Protocol drivers default to -ENOTSUP (most of their data is
          * not stored in any of their children (if they even have any),
@@ -8030,7 +8029,7 @@ void bdrv_refresh_filename(BlockDriverState *bs)
          *   Both of these conditions are represented by generate_json_filename.
          */
         if (primary_child_bs->exact_filename[0] &&
-            primary_child_bs->drv->bdrv_file_open &&
+            primary_child_bs->drv->protocol_name &&
             !drv->is_filter && !generate_json_filename)
         {
             strcpy(bs->exact_filename, primary_child_bs->exact_filename);