Using LTP's nfslock01 test, one of our internal testers found that
the Linux client can send a LOCK and a FREE_STATEID request at the
same time. The LOCK uses the same lockowner as the stateid sent in
the FREE_STATEID request.
The outcome is:
Frame 115025 C FREE_STATEID stateid 2/A
Frame 115026 C LOCK offset 672128 len 64
Frame 115029 R FREE_STATEID NFS4_OK
Frame 115030 R LOCK stateid 3/A
Frame 115034 C WRITE stateid 0/A offset 672128 len 64
Frame 115038 R WRITE NFS4ERR_BAD_STATEID
In other words, the server returns stateid A in the LOCK reply, but
it has already released it. Subsequent uses of the stateid fail.
To address this, protect the logic 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@xxxxxxxxxx>
Fix-suggested-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
Before I pass this along to Alexey for testing, I'd appreciate some
review of the proposed fix.
fs/nfsd/nfs4state.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b921123..a9e0606 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4911,16 +4911,24 @@ 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;
+ spin_unlock(&cl->cl_lock);
stp = openlockstateid(s);
+ mutex_lock(&stp->st_mutex);
+ ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
+ if (ret) {
+ mutex_unlock(&stp->st_mutex);
+ goto out;
+ }
ret = nfserr_locks_held;
if (check_for_locks(stp->st_stid.sc_file,
- lockowner(stp->st_stateowner)))
- break;
+ lockowner(stp->st_stateowner))) {
+ mutex_unlock(&stp->st_mutex);
+ goto out;
+ }
+ spin_lock(&cl->cl_lock);
WARN_ON(!unhash_lock_stateid(stp));
spin_unlock(&cl->cl_lock);
+ mutex_unlock(&stp->st_mutex);
nfs4_put_stid(s);
ret = nfs_ok;
goto out;
--
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