nfsd41: sequence operation

Implement the sequence operation conforming to
http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-26

Check for stale clientid (as derived from the sessionid).
Enforce slotid range and exactly-once semantics using
the slotid and seqid.

If everything went well renew the client lease and
mark the slot INPROGRESS.

Add a struct nfsd4_slot pointer to struct nfsd4_compound_state.
To be used for sessions DRC replay.

[nfsd41: rename sequence catchthis to cachethis]
Signed-off-by: Andy Adamson<andros@netapp.com>
[pulled some code to set cstate->slot from "nfsd DRC logic"]
[use sessionid_lock spin lock]
[nfsd41: use bool inuse for slot state]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd: add a struct nfsd4_slot pointer to struct nfsd4_compound_state]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41: add nfsd4_session pointer to nfsd4_compound_state]
[nfsd41: set cstate session]
[nfsd41: use cstate session in nfsd4_sequence]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[simplify nfsd4_encode_sequence error handling]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

3 files changed, 113 insertions, 6 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index dfc6d946cdfe..24b6e0593184 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1000,6 +1000,32 @@ error:
         return status;
 }
 
+static int
+check_slot_seqid(u32 seqid, struct nfsd4_slot *slot)
+{
+        dprintk("%s enter. seqid %d slot->sl_seqid %d\n", __func__, seqid,
+                slot->sl_seqid);
+
+        /* The slot is in use, and no response has been sent. */
+        if (slot->sl_inuse) {
+                if (seqid == slot->sl_seqid)
+                        return nfserr_jukebox;
+                else
+                        return nfserr_seq_misordered;
+        }
+        /* Normal */
+        if (likely(seqid == slot->sl_seqid + 1))
+                return nfs_ok;
+        /* Replay */
+        if (seqid == slot->sl_seqid)
+                return nfserr_replay_cache;
+        /* Wraparound */
+        if (seqid == 1 && (slot->sl_seqid + 1) == 0)
+                return nfs_ok;
+        /* Misordered replay or misordered new request */
+        return nfserr_seq_misordered;
+}
+
 __be32
 nfsd4_create_session(struct svc_rqst *rqstp,
                      struct nfsd4_compound_state *cstate,
@@ -1017,11 +1043,54 @@ nfsd4_destroy_session(struct svc_rqst *r,
 }
 
 __be32
-nfsd4_sequence(struct svc_rqst *r,
+nfsd4_sequence(struct svc_rqst *rqstp,
                struct nfsd4_compound_state *cstate,
                struct nfsd4_sequence *seq)
 {
-        return -1;      /* stub */
+        struct nfsd4_session *session;
+        struct nfsd4_slot *slot;
+        int status;
+
+        spin_lock(&sessionid_lock);
+        status = nfserr_badsession;
+        session = find_in_sessionid_hashtbl(&seq->sessionid);
+        if (!session)
+                goto out;
+
+        status = nfserr_badslot;
+        if (seq->slotid >= session->se_fnumslots)
+                goto out;
+
+        slot = &session->se_slots[seq->slotid];
+        dprintk("%s: slotid %d\n", __func__, seq->slotid);
+
+        status = check_slot_seqid(seq->seqid, slot);
+        if (status == nfserr_replay_cache) {
+                cstate->slot = slot;
+                cstate->session = session;
+                goto replay_cache;
+        }
+        if (status)
+                goto out;
+
+        /* Success! bump slot seqid */
+        slot->sl_inuse = true;
+        slot->sl_seqid = seq->seqid;
+
+        cstate->slot = slot;
+        cstate->session = session;
+
+replay_cache:
+        /* Renew the clientid on success and on replay.
+         * Hold a session reference until done processing the compound:
+         * nfsd4_put_session called only if the cstate slot is set.
+         */
+        renew_client(session->se_client);
+        nfsd4_get_session(session);
+out:
+        spin_unlock(&sessionid_lock);
+        dprintk("%s: return %d\n", __func__, ntohl(status));
+        return status;
 }
 
 __be32
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index bebf6d249069..8556575480ce 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1113,7 +1113,16 @@ static __be32
 nfsd4_decode_sequence(struct nfsd4_compoundargs *argp,
                       struct nfsd4_sequence *seq)
 {
-        return nfserr_opnotsupp;        /* stub */
+        DECODE_HEAD;
+
+        READ_BUF(NFS4_MAX_SESSIONID_LEN + 16);
+        COPYMEM(seq->sessionid.data, NFS4_MAX_SESSIONID_LEN);
+        READ32(seq->seqid);
+        READ32(seq->slotid);
+        READ32(seq->maxslots);
+        READ32(seq->cachethis);
+
+        DECODE_TAIL;
 }
 
 static __be32
@@ -2828,8 +2837,26 @@ static __be32
 nfsd4_encode_sequence(struct nfsd4_compoundres *resp, int nfserr,
                       struct nfsd4_sequence *seq)
 {
-        /* stub */
-        return nfserr;
+        ENCODE_HEAD;
+
+        if (nfserr)
+                return nfserr;
+
+        RESERVE_SPACE(NFS4_MAX_SESSIONID_LEN + 20);
+        WRITEMEM(seq->sessionid.data, NFS4_MAX_SESSIONID_LEN);
+        WRITE32(seq->seqid);
+        WRITE32(seq->slotid);
+        WRITE32(seq->maxslots);
+        /*
+         * FIXME: for now:
+         *   target_maxslots = maxslots
+         *   status_flags = 0
+         */
+        WRITE32(seq->maxslots);
+        WRITE32(0);
+
+        ADJUST_ARGS();
+        return 0;
 }
 
 static __be32
diff --git a/include/linux/nfsd/xdr4.h b/include/linux/nfsd/xdr4.h
index 33ee71e988b4..6e28a041008d 100644
--- a/include/linux/nfsd/xdr4.h
+++ b/include/linux/nfsd/xdr4.h
@@ -48,6 +48,9 @@ struct nfsd4_compound_state {
         struct svc_fh           current_fh;
         struct svc_fh           save_fh;
         struct nfs4_stateowner  *replay_owner;
+        /* For sessions DRC */
+        struct nfsd4_session    *session;
+        struct nfsd4_slot       *slot;
 };
 
 struct nfsd4_change_info {
@@ -358,7 +361,15 @@ struct nfsd4_create_session {
 };
 
 struct nfsd4_sequence {
-        int     foo;    /* stub */
+        struct nfs4_sessionid   sessionid;              /* request/response */
+        u32                     seqid;                  /* request/response */
+        u32                     slotid;                 /* request/response */
+        u32                     maxslots;               /* request/response */
+        u32                     cachethis;              /* request */
+#if 0
+        u32                     target_maxslots;        /* response */
+        u32                     status_flags;           /* response */
+#endif /* not yet */
 };
 
 struct nfsd4_destroy_session {