On Fri, Aug 30, 2013 at 01:43:11PM -0700, Linus Torvalds wrote:On Fri, Aug 30, 2013 at 1:15 PM, Waiman Long<waiman.long@xxxxxx> wrote:Not really. Sure, you'll retry it if you race with d_move(); that's notThe prepend_path() isn't all due to getcwd. The correct profile should beUgh. I really think that prepend_path() should just be rewritten to
run entirely under RCU.
Then we can remove *all* the stupid locking, and replace it with doing
a read-lock on the rename sequence count, and repeating if requited.
That shouldn't even be hard to do, it just requires mindless massaging
and being careful.
the real problem - access past the end of the object containing ->d_name.name
would screw you and that's what ->d_lock is preventing there. Delayed freeing
of what ->d_name is pointing into is fine, but it's not the only way to get
hurt there...