On Tue, Mar 23, 2021 at 5:07 PM Miklos Szeredi <mszeredi@xxxxxxxxxx> wrote: > > Overlayfs does not cache ACL's to avoid double caching with all its > problems. Instead it just calls the underlying filesystem's > i_op->get_acl(), which will return the cached value, if possible. > > In rcu path walk, however, get_cached_acl_rcu() is employed to get the > value from the cache, which will fail on overlayfs resulting in dropping > out of rcu walk mode. This can result in a big performance hit in certain > situations. > > Add a flags argument to the ->get_acl() callback, and allow > get_cached_acl_rcu() to call the ->get_acl() method with LOOKUP_RCU. > > Don't do this for the generic case of a cache miss, only in case of > ACL_DONT_CACHE. > > Reported-by: garyhuang <zjh.20052005@xxxxxxx> > Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> Hi Al, Could you please apply this patch? It's fairly trivial, but unfortunately adds a fair bit of API churn. Thanks, Miklos
