nfsd4: fix sessions slotid wraparound logic

From RFC 5661 2.10.6.1: "If the previous sequence ID was 0xFFFFFFFF,
then the next request for the slot MUST have the sequence ID set to
zero."

While we're there, delete some redundant comments.

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

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index e8c98f0096706c04e70456c35af2f8123241af7a..2095dbb2923ea2427832d02e3290d1ba72a768ae 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1575,16 +1575,11 @@ check_slot_seqid(u32 seqid, u32 slot_seqid, int slot_inuse)
                else
                        return nfserr_seq_misordered;
        }
-       /* Normal */
+       /* Note unsigned 32-bit arithmetic handles wraparound: */
        if (likely(seqid == slot_seqid + 1))
                return nfs_ok;
-       /* Replay */
        if (seqid == slot_seqid)
                return nfserr_replay_cache;
-       /* Wraparound */
-       if (seqid == 1 && (slot_seqid + 1) == 0)
-               return nfs_ok;
-       /* Misordered replay or misordered new request */
        return nfserr_seq_misordered;
 }