On Thu, Nov 09, 2023 at 06:20:48AM +0000, Al Viro wrote: > We have already checked it and dentry used to look not worthy > of keeping. The only hard obstacle to evicting dentry is > non-zero refcount; everything else is advisory - e.g. memory > pressure could evict any dentry found with refcount zero. > On the slow path in dentry_kill() we had dropped and regained > ->d_lock; we must recheck the refcount, but everything else > is not worth bothering with. > > Note that filesystem can not count upon ->d_delete() being > called for dentry - not even once. Again, memory pressure > (as well as d_prune_aliases(), or attempted rmdir() of ancestor, > or...) will not call ->d_delete() at all. > > So from the correctness point of view we are fine doing the > check only once. And it makes things simpler down the road. > > Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > --- Ok, that again relies on earlier patches that ensure that dentry_kill() isn't called with refcount == 0 afaiu, Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
