Re: [RFC PATCH 12/22] nbd/server: Simplify export shutdown

[Max Reitz <mreitz@redhat.com>]

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On 13.08.20 18:29, Kevin Wolf wrote:
> Closing export is somewhat convoluted because nbd_export_close() and
> nbd_export_put() call each other and the ways they actually end up being
> nested is not necessarily obvious.
> 
> However, it is not really necessary to call nbd_export_close() from
> nbd_export_put() when putting the last reference because it only does
> three things:
> 
> 1. Close all clients. We're going to refcount 0 and all clients hold a
>    reference, so we know there is no active client any more.
> 
> 2. Close the user reference (represented by exp->name being non-NULL).
>    The same argument applies: If the export were still named, we would
>    still have a reference.
> 
> 3. Freeing exp->description. This is really cleanup work to be done when
>    the export is finally freed. There is no reason to already clear it
>    while clients are still in the process of shutting down.

Convincing.

> So after moving the cleanup of exp->description, the code can be
> simplified so that only nbd_export_close() calls nbd_export_put(), but
> never the other way around.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  nbd/server.c | 17 ++++-------------
>  1 file changed, 4 insertions(+), 13 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>


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