On Fri, Oct 24, 2014 at 09:24:45AM +0200, Miklos Szeredi wrote: > The reason I didn't do your "fix" is that it > > - adds more lines than it takes, > > - I wasn't sure at all if the lockless access is actually correct > without the ACCESS_ONCE and all the memory barrier magic that might be > necessary on weird architectures.
_What_ lockless accesses? There is an extremely embarrassing bug in that commit, all right, but it has nothing to do with barriers... All barrier-related issues are taken care of by ovl_path_upper() (and without that you'd have tons of worse problems). Fetching ->upperfile outside of ->i_mutex is fine - in the worst case we'll fetch NULL, open the sucker grab ->i_mutex and find out that it has already been taken care of. In which case we fput() what we'd opened and move on (fput() under ->i_mutex is fine - it's going to be delayed until return from syscall anyway). There was a very dumb braino in there; fixed, force-pushed, passes unionmount tests, no regressions on LTP syscall ones and xfstests. -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
