On Wed, May 25, 2016 at 05:57:29PM -0400, Jeff Layton wrote: > On Wed, 2016-05-25 at 13:42 -0400, J. Bruce Fields wrote: > > On Wed, May 25, 2016 at 08:30:44AM -0400, Jeff Layton wrote: > > > > > > Maybe it's time to start thinking about how to support multiple layout > > > types per export? > > It looks like nobody would want this flex file code in production. The > > only users will be testers and developers. > > > > And the scsi layout is really just a replacement for the block layout, > > nobody should be supporting both of those at once either. > > > > Well...unless you have a mix of clients that just support block and > some that support scsi. Is that plausible? Maybe so. I don't think it would be useful to support, though. (I'd rather people skipped straight to scsi. And block never got much use, so I don't think that should be hard. But if you're really stuck with some block clients, I suspect you may as well use block for all of them--the scsi clients could probably do block layout too, and I think you only get all the advantages of the scsi layout if all your clients are using it.) > > Would it be too much of a burden just to make flexfiles and developers > > build their own kernels? > > > > > It doesn't look like it would be that hard. I think > > > we could convert ex_layout_type into a bitmap that shows which types > > > are supported. > > ex_layout_type is only used internally, the only external interface is > > an export flag, so we'd need some new interface. > > > > I was thinking that with the "pnfs" export option you'd just enable any > layouts that the fs supports. So here, you could theoretically allow > nfsd to offer up block, scsi and flexfiles layouts given the right fs, > and leave the decision of the layout type to actually use up to the > client. OK. In this particular case that seems less interesting than just the ability to turn flexfiles on and off from user space, so testers can enable it without having to build a new kernel. Hopefully we can figure out how to make this useful in production some day, and then maybe the multiple-layout support becomes more interesting. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
