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authorChuck Lever <chuck.lever@oracle.com>2016-08-11 10:37:30 -0400
committerJ. Bruce Fields <bfields@redhat.com>2016-08-11 15:08:39 -0400
commit42691398be08bd1fe99326911a0aa31f2c041d53 (patch)
tree1a0674b92269c6ed774b755189764f84c4687061 /fs/nfsd
parent502aa0a5be633e6558574ebcf63b65afdfbfcd7a (diff)
nfsd: Fix race between FREE_STATEID and LOCK
When running LTP's nfslock01 test, the Linux client can send a LOCK and a FREE_STATEID request at the same time. The outcome is: Frame 324 R OPEN stateid [2,O] Frame 115004 C LOCK lockowner_is_new stateid [2,O] offset 672000 len 64 Frame 115008 R LOCK stateid [1,L] Frame 115012 C WRITE stateid [0,L] offset 672000 len 64 Frame 115016 R WRITE NFS4_OK Frame 115019 C LOCKU stateid [1,L] offset 672000 len 64 Frame 115022 R LOCKU NFS4_OK Frame 115025 C FREE_STATEID stateid [2,L] Frame 115026 C LOCK lockowner_is_new stateid [2,O] offset 672128 len 64 Frame 115029 R FREE_STATEID NFS4_OK Frame 115030 R LOCK stateid [3,L] Frame 115034 C WRITE stateid [0,L] offset 672128 len 64 Frame 115038 R WRITE NFS4ERR_BAD_STATEID In other words, the server returns stateid L in a successful LOCK reply, but it has already released it. Subsequent uses of stateid L fail. To address this, protect the generation check in nfsd4_free_stateid with the st_mutex. This should guarantee that only one of two outcomes occurs: either LOCK returns a fresh valid stateid, or FREE_STATEID returns NFS4ERR_LOCKS_HELD. Reported-by: Alexey Kodanev <alexey.kodanev@oracle.com> Fix-suggested-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com> Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/nfs4state.c40
1 files changed, 28 insertions, 12 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 8410ca275db1..0edc1822f144 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4903,6 +4903,32 @@ nfsd4_test_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
return nfs_ok;
}
+static __be32
+nfsd4_free_lock_stateid(stateid_t *stateid, struct nfs4_stid *s)
+{
+ struct nfs4_ol_stateid *stp = openlockstateid(s);
+ __be32 ret;
+
+ mutex_lock(&stp->st_mutex);
+
+ ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
+ if (ret)
+ goto out;
+
+ ret = nfserr_locks_held;
+ if (check_for_locks(stp->st_stid.sc_file,
+ lockowner(stp->st_stateowner)))
+ goto out;
+
+ release_lock_stateid(stp);
+ ret = nfs_ok;
+
+out:
+ mutex_unlock(&stp->st_mutex);
+ nfs4_put_stid(s);
+ return ret;
+}
+
__be32
nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
struct nfsd4_free_stateid *free_stateid)
@@ -4910,7 +4936,6 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
stateid_t *stateid = &free_stateid->fr_stateid;
struct nfs4_stid *s;
struct nfs4_delegation *dp;
- struct nfs4_ol_stateid *stp;
struct nfs4_client *cl = cstate->session->se_client;
__be32 ret = nfserr_bad_stateid;
@@ -4929,18 +4954,9 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
ret = nfserr_locks_held;
break;
case NFS4_LOCK_STID:
- ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
- if (ret)
- break;
- stp = openlockstateid(s);
- ret = nfserr_locks_held;
- if (check_for_locks(stp->st_stid.sc_file,
- lockowner(stp->st_stateowner)))
- break;
- WARN_ON(!unhash_lock_stateid(stp));
+ atomic_inc(&s->sc_count);
spin_unlock(&cl->cl_lock);
- nfs4_put_stid(s);
- ret = nfs_ok;
+ ret = nfsd4_free_lock_stateid(stateid, s);
goto out;
case NFS4_REVOKED_DELEG_STID:
dp = delegstateid(s);