In message <Pine.LNX.4.64.0711121645090.14138@xxxxxxxxxxxxxxxxxxxxxx>, Hugh Dickins writes: > On Fri, 9 Nov 2007, Erez Zadok wrote: > > In message <Pine.LNX.4.64.0711051358440.7629@xxxxxxxxxxxxxxxxxxxxxx>, Hugh Dickins writes: > > > > > Three, I believe you need to add a flush_dcache_page(lower_page) > > > after the copy_highpage(lower_page): some architectures will need > > > that to see the new data if they have lower_page mapped (though I > > > expect it's anyway shaky ground to be accessing through the lower > > > mount at the same time as modifying through the upper). > > > > OK. > > While looking into something else entirely, I realize that _here_ > you are missing a SetPageUptodate(lower_page): should go in after > the flush_dcache_page(lower_page) I'm suggesting. (Nick would argue > for some kind of barrier there too, but I don't think unionfs has a > special need to be ahead of the pack on that issue.) > > Think about it: > when find_or_create_page has created a fresh page in the cache, > and you've just done copy_highpage to put the data into it, you > now need to mark it as Uptodate: otherwise a subsequent vfs_read > or whatever on the lower level will find that page !Uptodate and > read stale data back from disk instead of what you just copied in, > unless its dirtiness has got it written back to disk meanwhile. Hehe. Funny, you mention this... A few days ago, while I was doing your other recommended pageuptodate cleanups, I also added the same call to SetPageUptodate(lower_page) as you suggested. I tested that change along w/ the other changes you suggested, and they all seem to work great all the way from my 2.6.9 backport to 2.6.24-rc2 and -mm (modulo the fact that I had to work around or fix more non-unionfs bugs in -mm than unionfs ones to get it to work :-) I posted all of these patches just now. You're CC'ed. Hopefully Andrew can pull from my unionfs.git branch soon. You also reported in your previous emails some hangs/oopses while doing make -j 20 in unionfs on top of a single tmpfs, using -mm. After several days, I've not been able to reproduce this w/ my latest set of patches. If you can send me your .config and the specs on the h/w you're using (cpus, mem, etc.), I'll see if I can find something similar to it on my end and run the same tests. Cheers, Erez. - 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
