On Mon 26-09-16 02:08:05, Christoph Hellwig wrote: > On Fri, Sep 23, 2016 at 03:02:37PM -0600, Ross Zwisler wrote: > > I can just add a hack to hop over the writeback in generic_file_read_iter(), > > but I hesitate to do this because it seems like the correct thing to do is to > > separate the ext4 DAX & DIO paths, which I think you are already doing. > > I've started on it, and the read path works fine. I'm a bit stuck on > the write side as my attempts at it seems to corrupt data fairly easily > when running xfstests. Well, I have a bunch of data corruption fixes for DAX sitting in my tree which I was able to trigger. E.g. there are some missing invalidations of blockdev aliases, also some races between fault vs write path the can lead to data loss. But at least the second fix requires clearing of dirty bits in the radix tree for DAX and that is a big pile of patches I have to sift through mm people (and related mm parts are in constant churn due to PMD pages in pagecache work so it is a mess). > > I believe that my DAX PMD patches are ready to go, but because of this issue > > they currently only support XFS. I'm tempted to send them out as they are > > right now since they add a bunch of complexity to DAX that we need to review, > > and that review can fully happen with only XFS support. We can add ext4 > > support back in later when it's ready. > > Yes, please send them out. We really should move ext4 over to iomap for > DAX. I'd love to get some help from someone more familar with ext4, > and can send my code dump to get started. Yeah, I'd also just implement it for iomap path and XFS as a start and then I'll port ext4 over to iomap infrastructure for DAX. There should be no principial problem. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- 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
