On Thu, Nov 24, 2011 at 02:14:30PM +0100, Emmanuel Dreyfus wrote: > > When calling lookup, the parent (directory) is supposed to be locked > > to prevent exactly this sort of thing from happening. You and/or > > perfuse and/or puffs ignore this at your peril, because doing so > > violates atomicitiy guarantees and assumptions made by upper-level > > code. > > I don't violate the need for a locked vnode during lookup, the problem > is with distributed filesystem, where another machine delete the > directory.
It's not just the vnode that's supposed to be locked; it's the *directory*, IOW the contents. If it's not, open with O_CREAT|O_EXCL will probably not work reliably, which is in turn a security hazard. Although it's perhaps no worse than nfs then... > > However, if it's really disappeared, why not just fail with ENOENT? > > ENOENT tells the kernel that the entry it looked up does not exists. It > does not tell anything about the parent vnode being now stale. What does NFS do for ESTALE cases? Whatever it is, there's probably a way to do it via fuse, and therefore also via perfuse. -- David A. Holland dholl...@netbsd.org
