From: NeilBrown Date: Mon, 4 Aug 2014 06:24:00 +0000 (+1000) Subject: NFS: fix two problems in lookup_revalidate in RCU-walk X-Git-Tag: cleanup-for-v3.18~41^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=50d77739fa1972030daf1c8902404551e49bf232;p=pandora-kernel.git 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 Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust --- Reading git-diff-tree failed