Re: [PATCH v9 2/7] block/export: add blk_by_export_id()

[Vladimir Sementsov-Ogievskiy]

On 18.07.24 14:48, Markus Armbruster wrote:
> Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
>
> > We need it for further blockdev-replace functionality.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> > ---
> >   block/export/export.c                       | 18 ++++++++++++++++++
> >   include/sysemu/block-backend-global-state.h |  1 +
> >   2 files changed, 19 insertions(+)
> >
> > diff --git a/block/export/export.c b/block/export/export.c
> > index 6d51ae8ed7..57beae7982 100644
> > --- a/block/export/export.c
> > +++ b/block/export/export.c
> > @@ -355,3 +355,21 @@ BlockExportInfoList *qmp_query_block_exports(Error **errp)
> >   
> >       return head;
> >   }
> > +
> > +BlockBackend *blk_by_export_id(const char *id, Error **errp)
> > +{
> > +    BlockExport *exp;
> > +
> > +    exp = blk_exp_find(id);
> > +    if (exp == NULL) {
> > +        error_setg(errp, "Export '%s' not found", id);
> > +        return NULL;
> > +    }
> > +
> > +    if (!exp->blk) {
> > +        error_setg(errp, "Export '%s' is empty", id);
>
> Can this happen?

Hmm, looking at the code in blk_exp_add:

    assert(exp->blk != NULL);
                                                                                 
    QLIST_INSERT_HEAD(&block_exports, exp, next);
    return exp;


seems not. And I can't find anything changing exp->blk except for blk_exp_add().

Will switch to assertion.

> > +        return NULL;
> > +    }
> > +
> > +    return exp->blk;
> > +}
> > diff --git a/include/sysemu/block-backend-global-state.h 
> > b/include/sysemu/block-backend-global-state.h
> > index ccb35546a1..410d0cc5c7 100644
> > --- a/include/sysemu/block-backend-global-state.h
> > +++ b/include/sysemu/block-backend-global-state.h
> > @@ -74,6 +74,7 @@ void blk_detach_dev(BlockBackend *blk, DeviceState *dev);
> >   DeviceState *blk_get_attached_dev(BlockBackend *blk);
> >   BlockBackend *blk_by_dev(void *dev);
> >   BlockBackend *blk_by_qdev_id(const char *id, Error **errp);
> > +BlockBackend *blk_by_export_id(const char *id, Error **errp);
> >   void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque);
> >   
> >   void blk_activate(BlockBackend *blk, Error **errp);

--
Best regards,
Vladimir