qemu-img bitmap: Report errors while closing the image

blk_unref() can't report any errors that happen while closing the image.
For example, if qcow2 hits an -ENOSPC error while writing out dirty
bitmaps when it's closed, it prints error messages to stderr, but
'qemu-img bitmap' won't see any error return value and will therefore
look successful with exit code 0.

In order to fix this, manually inactivate the image first before calling
blk_unref(). This already performs the operations that would be most
likely to fail while closing the image, but it can still return errors.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1330
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230112191454.169353-4-kwolf@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qemu-img.c

@@ -4646,6 +4646,7 @@ static int img_bitmap(int argc, char **argv)
     QSIMPLEQ_HEAD(, ImgBitmapAction) actions;
     ImgBitmapAction *act, *act_next;
     const char *op;
+    int inactivate_ret;
 
     QSIMPLEQ_INIT(&actions);
 
@@ -4830,6 +4831,16 @@ static int img_bitmap(int argc, char **argv)
     ret = 0;
 
  out:
+    /*
+     * Manually inactivate the images first because this way we can know whether
+     * an error occurred. blk_unref() doesn't tell us about failures.
+     */
+    inactivate_ret = bdrv_inactivate_all();
+    if (inactivate_ret < 0) {
+        error_report("Error while closing the image: %s", strerror(-inactivate_ret));
+        ret = 1;
+    }
+
     blk_unref(src);
     blk_unref(blk);
     qemu_opts_del(opts);