Re: [Qemu-devel] [PATCH v8 06/16] nbd: Switch from close to eject notifier

[Fam Zheng <famz@redhat.com>]

On Wed, 01/27 18:59, Max Reitz wrote:
> The NBD code uses the BDS close notifier to determine when a medium is
> ejected. However, now it should use the BB's BDS removal notifier for
> that instead of the BDS's close notifier.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  blockdev-nbd.c | 40 +++++-----------------------------------
>  nbd/server.c   | 13 +++++++++++++
>  2 files changed, 18 insertions(+), 35 deletions(-)
> 
> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> index 4a758ac..9d6a21c 100644
> --- a/blockdev-nbd.c
> +++ b/blockdev-nbd.c
> @@ -45,37 +45,11 @@ void qmp_nbd_server_start(SocketAddress *addr, Error **errp)
>      }
>  }
>  
> -/*
> - * Hook into the BlockBackend notifiers to close the export when the
> - * backend is closed.
> - */
> -typedef struct NBDCloseNotifier {
> -    Notifier n;
> -    NBDExport *exp;
> -    QTAILQ_ENTRY(NBDCloseNotifier) next;
> -} NBDCloseNotifier;
> -
> -static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers =
> -    QTAILQ_HEAD_INITIALIZER(close_notifiers);
> -
> -static void nbd_close_notifier(Notifier *n, void *data)
> -{
> -    NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n);
> -
> -    notifier_remove(&cn->n);
> -    QTAILQ_REMOVE(&close_notifiers, cn, next);
> -
> -    nbd_export_close(cn->exp);
> -    nbd_export_put(cn->exp);
> -    g_free(cn);
> -}
> -
>  void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
>                          Error **errp)
>  {
>      BlockBackend *blk;
>      NBDExport *exp;
> -    NBDCloseNotifier *n;
>  
>      if (server_fd == -1) {
>          error_setg(errp, "NBD server not running");
> @@ -113,19 +87,15 @@ void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
>  
>      nbd_export_set_name(exp, device);
>  
> -    n = g_new0(NBDCloseNotifier, 1);
> -    n->n.notify = nbd_close_notifier;
> -    n->exp = exp;
> -    blk_add_close_notifier(blk, &n->n);
> -    QTAILQ_INSERT_TAIL(&close_notifiers, n, next);
> +    /* The list of named exports has a strong reference to this export now and
> +     * our only way of accessing it is through nbd_export_find(), so we can drop
> +     * the strong reference that is @exp. */

Not quite sure about the meaning of "the strong reference that is @exp", I
guess you mean the one reference born in nbd_export_new(), which would match
the code.  Other than this,

Reviewed-by: Fam Zheng <famz@redhat.com>