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From:   Scott Mayhew <smayhew@redhat.com>
To:     bfields@fieldses.org, chuck.lever@oracle.com
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH] nfsd4: fix up replay_matches_cache()
Date:   Wed,  9 Oct 2019 15:11:37 -0400
Message-Id: <20191009191137.28007-1-smayhew@redhat.com>
Sender: linux-nfs-owner@vger.kernel.org
Precedence: bulk

When running an nfs stress test, I see quite a few cached replies that
don't match up with the actual request.  The first comment in
replay_matches_cache() makes sense, but the code doesn't seem to
match... fix it.

Fixes: 53da6a53e1d4 ("nfsd4: catch some false session retries")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 fs/nfsd/nfs4state.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c65aeaa812d4..08f6eb2b73f8 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3548,12 +3548,17 @@ static bool replay_matches_cache(struct svc_rqst *rqstp,
 	    (bool)seq->cachethis)
 		return false;
 	/*
-	 * If there's an error than the reply can have fewer ops than
-	 * the call.  But if we cached a reply with *more* ops than the
-	 * call you're sending us now, then this new call is clearly not
-	 * really a replay of the old one:
+	 * If there's an error then the reply can have fewer ops than
+	 * the call.
 	 */
-	if (slot->sl_opcnt < argp->opcnt)
+	if (slot->sl_opcnt < argp->opcnt && !slot->sl_status)
+		return false;
+	/*
+	 * But if we cached a reply with *more* ops than the call you're
+	 * sending us now, then this new call is clearly not really a
+	 * replay of the old one:
+	 */
+	if (slot->sl_opcnt > argp->opcnt)
 		return false;
 	/* This is the only check explicitly called by spec: */
 	if (!same_creds(&rqstp->rq_cred, &slot->sl_cred))
-- 
2.17.2