nfsd4: extend state lock over seqid replay logic

There are currently a couple races in the seqid replay code: a
retransmission could come while we're still encoding the original reply,
or a new seqid-mutating call could come as we're encoding a replay.

So, extend the state lock over the encoding (both encoding of a replayed
reply and caching of the original encoded reply).

I really hate doing this, and previously added the stateowner
reference-counting code to avoid it (which was insufficient)--but I
don't see a less complicated alternative at the moment.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 50bae74..50063a8 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -408,8 +408,8 @@ out:
        if (open->op_stateowner) {
                nfs4_get_stateowner(open->op_stateowner);
                cstate->replay_owner = open->op_stateowner;
-       }
-       nfs4_unlock_state();
+       } else
+               nfs4_unlock_state();
        return status;
 }
 
@@ -1227,6 +1227,7 @@ encode_op:
                        be32_to_cpu(status));
 
                if (cstate->replay_owner) {
+                       nfs4_unlock_state();
                        nfs4_put_stateowner(cstate->replay_owner);
                        cstate->replay_owner = NULL;
                }

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index bc1a9db..6cf729a 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3501,7 +3501,8 @@ nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
        nfsd4_create_clid_dir(sop->so_client);
 out:
-       nfs4_unlock_state();
+       if (!cstate->replay_owner)
+               nfs4_unlock_state();
        return status;
 }
 
@@ -3568,7 +3569,8 @@ nfsd4_open_downgrade(struct svc_rqst *rqstp,
        memcpy(&od->od_stateid, &stp->st_stateid, sizeof(stateid_t));
        status = nfs_ok;
 out:
-       nfs4_unlock_state();
+       if (!cstate->replay_owner)
+               nfs4_unlock_state();
        return status;
 }
 
@@ -3609,7 +3611,8 @@ nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
        if (list_empty(&so->so_stateids))
                move_to_close_lru(so);
 out:
-       nfs4_unlock_state();
+       if (!cstate->replay_owner)
+               nfs4_unlock_state();
        return status;
 }
 
@@ -4071,7 +4074,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 out:
        if (status && lock->lk_is_new && lock_sop)
                release_lockowner(lock_sop);
-       nfs4_unlock_state();
+       if (!cstate->replay_owner)
+               nfs4_unlock_state();
        return status;
 }