From 4a0954ef347de7409ddf8f8153d893827d3feba8 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 2 Oct 2015 11:11:16 -0400 Subject: [PATCH] NFSv4: Don't try to reclaim unused state owners Currently, we don't test if the state owner is in use before we try to recover it. The problem is that if the refcount is zero, then the state owner will be waiting on the lru list for garbage collection. The expectation in that case is that if you bump the refcount, then you must also remove the state owner from the lru list. Otherwise the call to nfs4_put_state_owner will corrupt that list by trying to add our state owner a second time. Avoid the whole problem by just skipping state owners that hold no state. Reported-by: Andrew W Elble Signed-off-by: Trond Myklebust --- fs/nfs/nfs4state.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index 5db324635e92..d854693a15b0 100644 --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -1725,7 +1725,8 @@ restart: if (!test_and_clear_bit(ops->owner_flag_bit, &sp->so_flags)) continue; - atomic_inc(&sp->so_count); + if (!atomic_inc_not_zero(&sp->so_count)) + continue; spin_unlock(&clp->cl_lock); rcu_read_unlock();