NFSv4: Fix races between nfs_remove_bad_delegation() and delegation return

[firefly-linux-kernel-4.4.55.git] / fs / nfs / delegation.c

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 3fa904c9e7efb31623567d195d49bb94c3014194..ef0c394b7bf55cc5891e01fc4647acff2db41307 100644 (file)
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -177,7 +177,11 @@ static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *
 {
        int res = 0;
 
-       res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
+       if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
+               res = nfs4_proc_delegreturn(inode,
+                               delegation->cred,
+                               &delegation->stateid,
+                               issync);
        nfs_free_delegation(delegation);
        return res;
 }
@@ -363,11 +367,13 @@ static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation
 {
        struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
        struct nfs_inode *nfsi = NFS_I(inode);
-       int err;
+       int err = 0;
 
        if (delegation == NULL)
                return 0;
        do {
+               if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
+                       break;
                err = nfs_delegation_claim_opens(inode, &delegation->stateid);
                if (!issync || err != -EAGAIN)
                        break;
@@ -588,10 +594,23 @@ static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *cl
        rcu_read_unlock();
 }
 
+static void nfs_revoke_delegation(struct inode *inode)
+{
+       struct nfs_delegation *delegation;
+       rcu_read_lock();
+       delegation = rcu_dereference(NFS_I(inode)->delegation);
+       if (delegation != NULL) {
+               set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
+               nfs_mark_return_delegation(NFS_SERVER(inode), delegation);
+       }
+       rcu_read_unlock();
+}
+
 void nfs_remove_bad_delegation(struct inode *inode)
 {
        struct nfs_delegation *delegation;
 
+       nfs_revoke_delegation(inode);
        delegation = nfs_inode_detach_delegation(inode);
        if (delegation) {
                nfs_inode_find_state_and_recover(inode, &delegation->stateid);