If the a format BDS's file BDS is in turn a format BDS, we cannot simply use the same filename, because when opening a BDS tree based on a filename alone, qemu will create only one format node on top of one protocol node (disregarding a potential backing file).
Signed-off-by: Max Reitz <mre...@redhat.com> --- block.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index 275cae460a..526ce43e9b 100644 --- a/block.c +++ b/block.c @@ -5104,9 +5104,20 @@ void bdrv_refresh_filename(BlockDriverState *bs) bs->exact_filename[0] = '\0'; - /* If no specific options have been given for this BDS, the filename of - * the underlying file should suffice for this one as well */ - if (bs->file->bs->exact_filename[0] && !generate_json_filename) { + /* We can use the underlying file's filename if: + * - it has a filename, + * - the file is a protocol BDS, and + * - opening that file (as this BDS's format) will automatically create + * the BDS tree we have right now, that is: + * - the user did not significantly change this BDS's behavior with + * some explicit options + * - no non-file child of this BDS has been overridden by the user + * Both of these conditions are represented by generate_json_filename. + */ + if (bs->file->bs->exact_filename[0] && + bs->file->bs->drv->bdrv_file_open && + !generate_json_filename) + { strcpy(bs->exact_filename, bs->file->bs->exact_filename); } } -- 2.13.6