nfsd: Fix races with check_stateid_generation()

The various functions that call check_stateid_generation() in order
to compare a client-supplied stateid with the nfs4_stid state, usually
need to atomically check for closed state. Those that perform the
check after locking the st_mutex using nfsd4_lock_ol_stateid()
should now be OK, but we do want to fix up the others.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index da07c24..ecb803d 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4906,6 +4906,18 @@ static __be32 check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_s
        return nfserr_old_stateid;
 }
 
+static __be32 nfsd4_stid_check_stateid_generation(stateid_t *in, struct nfs4_stid *s, bool has_session)
+{
+       __be32 ret;
+
+       spin_lock(&s->sc_lock);
+       ret = nfsd4_verify_open_stid(s);
+       if (ret == nfs_ok)
+               ret = check_stateid_generation(in, &s->sc_stateid, has_session);
+       spin_unlock(&s->sc_lock);
+       return ret;
+}
+
 static __be32 nfsd4_check_openowner_confirmed(struct nfs4_ol_stateid *ols)
 {
        if (ols->st_stateowner->so_is_open_owner &&
@@ -4934,7 +4946,7 @@ static __be32 nfsd4_validate_stateid(struct nfs4_client *cl, stateid_t *stateid)
        s = find_stateid_locked(cl, stateid);
        if (!s)
                goto out_unlock;
-       status = check_stateid_generation(stateid, &s->sc_stateid, 1);
+       status = nfsd4_stid_check_stateid_generation(stateid, s, 1);
        if (status)
                goto out_unlock;
        switch (s->sc_type) {
@@ -5095,7 +5107,7 @@ nfs4_preprocess_stateid_op(struct svc_rqst *rqstp,
                                &s, nn);
        if (status)
                return status;
-       status = check_stateid_generation(stateid, &s->sc_stateid,
+       status = nfsd4_stid_check_stateid_generation(stateid, s,
                        nfsd4_has_session(cstate));
        if (status)
                goto out;
@@ -5188,6 +5200,7 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
        s = find_stateid_locked(cl, stateid);
        if (!s)
                goto out_unlock;
+       spin_lock(&s->sc_lock);
        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                ret = nfserr_locks_held;
@@ -5199,11 +5212,13 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                ret = nfserr_locks_held;
                break;
        case NFS4_LOCK_STID:
+               spin_unlock(&s->sc_lock);
                refcount_inc(&s->sc_count);
                spin_unlock(&cl->cl_lock);
                ret = nfsd4_free_lock_stateid(stateid, s);
                goto out;
        case NFS4_REVOKED_DELEG_STID:
+               spin_unlock(&s->sc_lock);
                dp = delegstateid(s);
                list_del_init(&dp->dl_recall_lru);
                spin_unlock(&cl->cl_lock);
@@ -5212,6 +5227,7 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                goto out;
        /* Default falls through and returns nfserr_bad_stateid */
        }
+       spin_unlock(&s->sc_lock);
 out_unlock:
        spin_unlock(&cl->cl_lock);
 out:
@@ -5491,7 +5507,7 @@ nfsd4_delegreturn(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
        if (status)
                goto out;
        dp = delegstateid(s);
-       status = check_stateid_generation(stateid, &dp->dl_stid.sc_stateid, nfsd4_has_session(cstate));
+       status = nfsd4_stid_check_stateid_generation(stateid, &dp->dl_stid, nfsd4_has_session(cstate));
        if (status)
                goto put_stateid;