blockdev: Split monitor reference from BB creation

Before this patch, blk_new() automatically assigned a name to the new
BlockBackend and considered it referenced by the monitor. This patch
removes the implicit monitor_add_blk() call from blk_new() (and
consequently the monitor_remove_blk() call from blk_delete(), too) and
thus blk_new() (and related functions) no longer take a BB name
argument.

In fact, there is only a single point where blk_new()/blk_new_open() is
called and the new BB is monitor-owned, and that is in blockdev_init().
Besides thus relieving us from having to invent names for all of the BBs
we use in qemu-img, this fixes a bug where qemu cannot create a new
image if there already is a monitor-owned BB named "image".

If a BB and its BDS tree are created in a single operation, as of this
patch the BDS tree will be created before the BB is given a name
(whereas it was the other way around before). This results in minor
change to the output of iotest 087, whose reference output is amended
accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/qemu-nbd.c b/qemu-nbd.c
index a5c1d95344..d5f847386f 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -831,13 +831,13 @@ int main(int argc, char **argv)
         }
         options = qemu_opts_to_qdict(opts, NULL);
         qemu_opts_reset(&file_opts);
-        blk = blk_new_open("hda", NULL, NULL, options, flags, &local_err);
+        blk = blk_new_open(NULL, NULL, options, flags, &local_err);
     } else {
         if (fmt) {
             options = qdict_new();
             qdict_put(options, "driver", qstring_from_str(fmt));
         }
-        blk = blk_new_open("hda", srcpath, NULL, options, flags, &local_err);
+        blk = blk_new_open(srcpath, NULL, options, flags, &local_err);
     }
 
     if (!blk) {