NFSv4: Don't remove the delegation from the super_list more than once

Add a check to ensure that we haven't already removed the delegation
from the inode after we take all the relevant locks.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 0c9339d..e80419a 100644 (file)
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -298,6 +298,10 @@ nfs_detach_delegation_locked(struct nfs_inode *nfsi,
                return NULL;
 
        spin_lock(&delegation->lock);
+       if (!delegation->inode) {
+               spin_unlock(&delegation->lock);
+               return NULL;
+       }
        set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
        list_del_rcu(&delegation->super_list);
        delegation->inode = NULL;