At Thu, 26 Sep 2013 19:29:06 -0700, ronnie sahlberg wrote: > > On Thu, Sep 26, 2013 at 6:59 PM, Dan Mick <dan.mick@xxxxxxxxxxx> wrote: > > > >>> Some might say this had better to be a dynamic loadable > >>> library. Either is fine by me because it doesn't depend on any > >>> original C header files. > >> > >> > >> I'm ccing people who would be interested in modular backing > >> stores, Ronnie Sahlberg and Andy Grover. I think the sheepdog backing > >> store support doesn't have to be a module because it doesn't create > >> any new dependencies. Any comments? > > > > > > It seems that you've accomplished this by including structure and constant > > definitions (and presumably protocol-marshalling routines) in the tgt source > > file itself, which seems to me to be the wrong way to do it, but it does > > free you from requiring headers or libraries, so > > technically speaking, true. > > > > I wouldn't write the plugin this way (copying code), but that's me. > > > What Dan said! > Since you don't add any new dependencies it shouldn't matter if this > is built-in or a module. > > However, you do this at the cost of having a full blown > re-implementation (or it is a copy?) of a sheepdog client in the > backing store file. > I assume there are client libraries for sheepdog available? > > So I think from a maintenance viewpoint, it would probably be better > if you had the backend just be a thin layer that would call out to and > link to the sheepdog client library. > I.e. link to a sheedog library instead of reimplementing it in the backend. > And in that case then this should be a module. Thanks for your comment, Dan and Ronnie. Currently, sheepdog doesn't have its client library. We have a plan to implement it. But it will take time. In addition, the backing store support of sheepdog isn't a simple copy (from QEMU). We can't re-implement it by simple copy because current sheepdog users, QEMU and tgt, have very different I/O models. e.g. QEMU is a heavy user of coroutine. After implementing the library, the backing store support of sheepdog can be a module. But for now, this patch would be optimal because it doesn't increase the cost of tgt maintenance (the patch simply adds a single file). Thanks, Hitoshi -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
