Quoting Mike Snitzer (2013-11-06 15:36:40) > On Wed, Nov 06 2013 at 3:22pm -0500, > Chris Mason <chris.ma...@fusionio.com> wrote: > > > Quoting Kent Overstreet (2013-11-06 15:02:22) > > > On Wed, Nov 06, 2013 at 11:11:30AM -0500, Chris Mason wrote: > > > > > > > > I think the concept of bio ownership is still much too weak, at least > > > > for established users like MD and DM. I don't know how to verify the > > > > sharing of bi_io_vec without some kind of reference counting on the > > > > iovec. > > > > > > What's unclear about it? The rule is just - if you didn't allocate the > > > biovec, > > > don't modify it or use bio_for_each_segment_all() (probably I didn't > > > quite state > > > it clearly enough before though) > > > > That part makes sense. The new rule that scares me is that we can't > > free the src of the clone until all the clones are freed. If it works > > with today's existing users it feels like it is more by accident than > > design. I'm not saying we can't do it, we just need some bigger > > flashing warning lights. > > But we probably don't want those warning lights to come with the cost of > managing extra refcounts in the fast path -- so maybe a debug-only > refcount?
I'd be happy with some code comments and a few extra SOBs. In general I'm happy with the new patches that add _fast and make us explicitly choose the sharing. Lots of little chances for bugs, but opt-in is a much better starting point. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
