On Fri, Nov 11, 2016 at 01:33:08AM +0200, Amir Goldstein wrote: > I am certainly looking for this feedback, because there is no other means for > me to sanity test if relaxing lock_rename() is safe. > > When I write "any change of parent" I mean a change between 2 different > connected parents. Both work dir and upper dir are connected and with > reference held after mount. > Are the d_splice_alias() and __d_unalias() cases a real concern for moving > work dir around after the overlay mount?? Why not? Again, it's really up to you to provide an analysis of the call chains. There's nothing in d_splice_alias() to prohibit an existing alias being attached - in fact, __d_unalias() is called exactly in that case. It's a rare case, all right, but it is not impossible. BTW, your analysis would better be simple and explicit - anything subtle will be flat-out rejected, since it would have to be stepped around very carefully in any later work in VFS. I really wonder what it is that you are getting contention on - what are you doing, besides the actual renames? And that needs serialization anyway (on inode lock of workdir, if nothing else), so any contention would not disappear from dropped ->s_vfs_rename_mutex... -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
