Re: [Libguestfs] nbdkit: how to require use of filter

On Mon, May 02, 2022 at 10:25:44AM +0100, Nikolaus Rath wrote: > Hi, > > Is there a way for a nbdkit plugin to *require* use of a nbdkit filter > (specifically the nbdkit-blocksize-filter) programmatically? No it's not possible in general, you just have to document it. However as it's *blocksize* filter that you're talking about, I assume you mean that your filter has blocksize constraints, eg. that it cannot handle sub-sector requests. In this case it is possible to tell clients that they must not issue requests smaller than a certain size (and also hint about optimal and maximum sizes). You can do this by writing a .block_size callback. For example: https://gitlab.com/nbdkit/nbdkit/-/blob/1f5dc0679e570ca2fa149ceaa52922d70... Not all clients obey these (although these clients are buggy!)