On Sat, Aug 15, 2015 at 2:19 AM, Christoph Hellwig <hch@xxxxxx> wrote: > On Thu, Aug 13, 2015 at 10:51:11AM -0600, Ross Zwisler wrote: >> Update the annotation for the kaddr pointer returned by direct_access() >> so that it is a __pmem pointer. This is consistent with the PMEM driver >> and with how this direct_access() pointer is used in the DAX code. > > IFF we stick to the __pmem annotations this looks good. > > That beeing said I start to really dislike them. We don't special > accesors to read/write from pmem, we just need to explicitly commit > it if we want to make it persistent. So I really don't see the need > to treat it special and require all the force casts to and from the > attribute. I'm not going to put up much of a fight if it's really getting in the way.... That said, while we don't need special accessors we do need guarantees that anything that has written to a persistent memory address has done so in a way that wmb_pmem() is able to flush it. It's more of a "I've audited this code path for wmb_pmem() compatibility so use this api to write to pmem." Perhaps a better way to statically check for missed flushes might be to have acquire_pmem_for_write() + release() annotations and the final release does a wmb_pmem(), but as far as I can tell the sparse acquire/release annotations don't stack. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
