nfsd41: non-page DRC for solo sequence responses

A session inactivity time compound (lease renewal) or a compound where the
sequence operation has sa_cachethis set to FALSE do not require any pages
to be held in the v4.1 DRC. This is because struct nfsd4_slot is already
caching the session information.

Add logic to the nfs41 server to not cache response pages for solo sequence
responses.

Return nfserr_replay_uncached_rep on the operation following the sequence
operation when sa_cachethis is FALSE.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41: use cstate session in nfsd4_replay_cache_entry]
[nfsd41: rename nfsd4_no_page_in_cache]
[nfsd41 rename nfsd4_enc_no_page_replay]
[nfsd41 nfsd4_is_solo_sequence]
[nfsd41 change nfsd4_not_cached return]
Signed-off-by: Andy Adamson <andros@netapp.com>
[changed return type to bool]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41 drop parens in nfsd4_is_solo_sequence call]
Signed-off-by: Andy Adamson <andros@netapp.com>
[changed "== 0" to "!"]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

3 files changed, 76 insertions, 10 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 9e2ee75e0f7c..ae21a4efe36c 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -828,6 +828,34 @@ static struct nfsd4_operation nfsd4_ops[];
 static const char *nfsd4_op_name(unsigned opnum);
 
 /*
+ * This is a replay of a compound for which no cache entry pages
+ * were used. Encode the sequence operation, and if cachethis is FALSE
+ * encode the uncache rep error on the next operation.
+ */
+static __be32
+nfsd4_enc_uncached_replay(struct nfsd4_compoundargs *args,
+                         struct nfsd4_compoundres *resp)
+{
+        struct nfsd4_op *op;
+
+        dprintk("--> %s resp->opcnt %d ce_cachethis %u \n", __func__,
+                resp->opcnt, resp->cstate.slot->sl_cache_entry.ce_cachethis);
+
+        /* Encode the replayed sequence operation */
+        BUG_ON(resp->opcnt != 1);
+        op = &args->ops[resp->opcnt - 1];
+        nfsd4_encode_operation(resp, op);
+
+        /*return nfserr_retry_uncached_rep in next operation. */
+        if (resp->cstate.slot->sl_cache_entry.ce_cachethis == 0) {
+                op = &args->ops[resp->opcnt++];
+                op->status = nfserr_retry_uncached_rep;
+                nfsd4_encode_operation(resp, op);
+        }
+        return op->status;
+}
+
+/*
  * Enforce NFSv4.1 COMPOUND ordering rules.
  *
  * TODO:
@@ -895,7 +923,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
                 dprintk("nfsv4 compound op #%d/%d: %d (%s)\n",
                         resp->opcnt, args->opcnt, op->opnum,
                         nfsd4_op_name(op->opnum));
-
                 /*
                  * The XDR decode routines may have pre-set op->status;
                  * for example, if there is a miscellaneous XDR error
@@ -939,7 +966,10 @@ encode_op:
                 /* Only from SEQUENCE or CREATE_SESSION */
                 if (resp->cstate.status == nfserr_replay_cache) {
                         dprintk("%s NFS4.1 replay from cache\n", __func__);
-                        status = op->status;
+                        if (nfsd4_not_cached(resp))
+                                status = nfsd4_enc_uncached_replay(args, resp);
+                        else
+                                status = op->status;
                         goto out;
                 }
                 if (op->status == nfserr_replay_me) {
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 58f9797eb09e..04a395fb5dce 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1049,17 +1049,31 @@ nfsd4_store_cache_entry(struct nfsd4_compoundres *resp)
         /* Don't cache a failed OP_SEQUENCE. */
         if (resp->opcnt == 1 && op->opnum == OP_SEQUENCE && resp->cstate.status)
                 return;
+
         nfsd4_release_respages(entry->ce_respages, entry->ce_resused);
+        entry->ce_opcnt = resp->opcnt;
+        entry->ce_status = resp->cstate.status;
+
+        /*
+         * Don't need a page to cache just the sequence operation - the slot
+         * does this for us!
+         */
+
+        if (nfsd4_not_cached(resp)) {
+                entry->ce_resused = 0;
+                entry->ce_rpchdrlen = 0;
+                dprintk("%s Just cache SEQUENCE. ce_cachethis %d\n", __func__,
+                        resp->cstate.slot->sl_cache_entry.ce_cachethis);
+                return;
+        }
         entry->ce_resused = rqstp->rq_resused;
         if (entry->ce_resused > NFSD_PAGES_PER_SLOT + 1)
                 entry->ce_resused = NFSD_PAGES_PER_SLOT + 1;
         nfsd4_copy_pages(entry->ce_respages, rqstp->rq_respages,
                          entry->ce_resused);
-        entry->ce_status = resp->cstate.status;
         entry->ce_datav.iov_base = resp->cstate.statp;
         entry->ce_datav.iov_len = resv->iov_len - ((char *)resp->cstate.statp -
                                 (char *)page_address(rqstp->rq_respages[0]));
-        entry->ce_opcnt = resp->opcnt;
         /* Current request rpc header length*/
         entry->ce_rpchdrlen = (char *)resp->cstate.statp -
                                 (char *)page_address(rqstp->rq_respages[0]);
@@ -1096,13 +1110,28 @@ nfsd41_copy_replay_data(struct nfsd4_compoundres *resp,
  * cached page.  Replace any futher replay pages from the cache.
  */
 __be32
-nfsd4_replay_cache_entry(struct nfsd4_compoundres *resp)
+nfsd4_replay_cache_entry(struct nfsd4_compoundres *resp,
+                         struct nfsd4_sequence *seq)
 {
         struct nfsd4_cache_entry *entry = &resp->cstate.slot->sl_cache_entry;
         __be32 status;
 
         dprintk("--> %s entry %p\n", __func__, entry);
 
+        /*
+         * If this is just the sequence operation, we did not keep
+         * a page in the cache entry because we can just use the
+         * slot info stored in struct nfsd4_sequence that was checked
+         * against the slot in nfsd4_sequence().
+         *
+         * This occurs when seq->cachethis is FALSE, or when the client
+         * session inactivity timer fires and a solo sequence operation
+         * is sent (lease renewal).
+         */
+        if (seq && nfsd4_not_cached(resp)) {
+                seq->maxslots = resp->cstate.session->se_fnumslots;
+                return nfs_ok;
+        }
 
         if (!nfsd41_copy_replay_data(resp, entry)) {
                 /*
@@ -1330,7 +1359,7 @@ nfsd4_create_session(struct svc_rqst *rqstp,
                         cstate->slot = slot;
                         cstate->status = status;
                         /* Return the cached reply status */
-                        status = nfsd4_replay_cache_entry(resp);
+                        status = nfsd4_replay_cache_entry(resp, NULL);
                         goto out;
                 } else if (cr_ses->seqid != conf->cl_slot.sl_seqid + 1) {
                         status = nfserr_seq_misordered;
@@ -1380,6 +1409,8 @@ nfsd4_create_session(struct svc_rqst *rqstp,
 
         slot->sl_inuse = true;
         cstate->slot = slot;
+        /* Ensure a page is used for the cache */
+        slot->sl_cache_entry.ce_cachethis = 1;
 out:
         nfs4_unlock_state();
         dprintk("%s returns %d\n", __func__, ntohl(status));
@@ -1425,8 +1456,8 @@ nfsd4_sequence(struct svc_rqst *rqstp,
                 cstate->slot = slot;
                 cstate->session = session;
                 /* Return the cached reply status and set cstate->status
-                 * for nfsd4_svc_encode_compoundres processing*/
-                status = nfsd4_replay_cache_entry(resp);
+                 * for nfsd4_svc_encode_compoundres processing */
+                status = nfsd4_replay_cache_entry(resp, seq);
                 cstate->status = nfserr_replay_cache;
                 goto replay_cache;
         }
@@ -1436,6 +1467,10 @@ nfsd4_sequence(struct svc_rqst *rqstp,
         /* Success! bump slot seqid */
         slot->sl_inuse = true;
         slot->sl_seqid = seq->seqid;
+        slot->sl_cache_entry.ce_cachethis = seq->cachethis;
+        /* Always set the cache entry cachethis for solo sequence */
+        if (nfsd4_is_solo_sequence(resp))
+                slot->sl_cache_entry.ce_cachethis = 1;
 
         cstate->slot = slot;
         cstate->session = session;
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 671f9b96429b..64bc2150a6fa 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2975,7 +2975,7 @@ nfsd4_encode_destroy_session(struct nfsd4_compoundres *resp, int nfserr,
         return nfserr;
 }
 
-static __be32
+__be32
 nfsd4_encode_sequence(struct nfsd4_compoundres *resp, int nfserr,
                       struct nfsd4_sequence *seq)
 {
@@ -3192,7 +3192,8 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo
         iov->iov_len = ((char*)resp->p) - (char*)iov->iov_base;
         BUG_ON(iov->iov_len > PAGE_SIZE);
         if (resp->cstate.slot != NULL) {
-                if (resp->cstate.status == nfserr_replay_cache) {
+                if (resp->cstate.status == nfserr_replay_cache &&
+                                !nfsd4_not_cached(resp)) {
                         iov->iov_len = resp->cstate.iovlen;
                 } else {
                         nfsd4_store_cache_entry(resp);