NFS: fix two problems in lookup_revalidate in RCU-walk
1/ rcu_dereference isn't correct: that field isn't
RCU protected. It could potentially change at any time
so ACCESS_ONCE might be justified.
changes to ->d_parent are protected by ->d_seq. However
that isn't always checked after ->d_revalidate is called,
so it is safest to keep the double-check that ->d_parent
hasn't changed at the end of these functions.
2/ in nfs4_lookup_revalidate, "->d_parent" was forgotten.
So 'parent' was not the parent of 'dentry'.
This fails safe is the context is that dentry->d_inode is
NULL, and the result of parent->d_inode being NULL is
that ECHILD is returned, which is always safe.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
1 file changed