On Thu, 2007-08-30 at 16:30 -0700, Hua Zhong wrote: > There are two disjoint directories. I am wondering why there would be cache > coherency issues in this case? Is this Linus nfs implementation specific or > all other Unix systems all have the same issue?
How is the NFS client to know that these directories are disjoint, or that no-one will ever create a hard link from one directory to another? To my knowledge, the only way to ensure this is to put them on different disk partitions. I don't know if all Unix systems have this issue, but I have been told that Solaris at least has it. > > If you know what you are doing, then there is an option which allows > > you to override the default behaviour. > > > > > More importantly, it is a regression. My understanding is that unless > > > absolutely necessary we do not introduce a "feature" that breaks > > > working setups. > > > > Your turn to define what you mean by "working"? In my book that means > > "a setup that doesn't include unexpected or unintended behaviour". > > "working" as in "I can mount the directory and do my work". And there has > never been any problems as far as I know. That is too narrow a definition: the minimum should be "everyone can mount their directories and do their work". Your particular setup may be safe, but that is why we have overrides: the default should be for the kernel to be conservative, and to _tell_ users what it thinks is wrong. > > Not being able to notice cache coherency failures on a file that is > > mounted in two different places with two different sets of mount > > options counts as "unexpected behaviour". > > > > Not being able to notice that your mount options have been overridden > > by the kernel also counts as "unexpected behaviour". > > Fine. These are all very nice theories, but I just want to report this > regression and hope it won't cause any big problems for any users out there. > In the mean time, I am returning to 2.6.22. Your choice. Trond - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/