diff options
| -rw-r--r-- | block.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/block.c b/block.c index 9698f2ad44..c043f5eadd 100644 --- a/block.c +++ b/block.c @@ -3434,7 +3434,13 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, drv_prepared = true; - if (drv->supports_backing && reopen_state->backing_missing) { + /* + * We must provide the 'backing' option if the BDS has a backing + * file or if the image file has a backing file name as part of + * its metadata. Otherwise the 'backing' option can be omitted. + */ + if (drv->supports_backing && reopen_state->backing_missing && + (backing_bs(reopen_state->bs) || reopen_state->bs->backing_file[0])) { error_setg(errp, "backing is missing for '%s'", reopen_state->bs->node_name); ret = -EINVAL; |