On Sat, Jan 26, 2008 at 07:39:12PM +0000, David Holland wrote: > On Sat, Jan 26, 2008 at 05:57:50PM +0000, Andrew Doran wrote: > >> 4) I think we can rip out the "UPPER LOCK" stuff in layerfs. It dated > from > >> when lower file systems didn't do locking. The only thing now that > doesn't > >> export a vn_lock is unionfs, which does do correct locking. Sorry, I've > >> been meaning to kill it but haven't gotten to it. > > > > Sounds like union-over-union should be prevented? I'll see about removing > > it. Actually, a union-over-union should be fine in this respect. It could just call down for locking when it needed to. > It seems like if unionfs does proper locking, it ought to be able to > take unions of anything, including other unionfses. We should bar unions-of-unions for another reason, however. The hooks we use for merging readdir don't recurse right. So while the vnodes would work (I think), you couldn't correctly read a directory. Take care, Bill
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