NFSD: Delay adding new entries to LRU

Neil Brown observes:
> I would not include RC_INPROG entries in the lru at all - they are
> always ignored, and will be added when they are switched to
> RCU_DONE.

I also removed a stale comment.

Suggested-by: NeilBrown <neil@brown.name>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: chucklever

fs/nfsd/nfscache.c

@@ -237,10 +237,6 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
 
 }
 
-/*
- * Move cache entry to end of LRU list, and queue the cleaner to run if it's
- * not already scheduled.
- */
 static void
 lru_put_end(struct nfsd_drc_bucket *b, struct nfsd_cacherep *rp)
 {
@@ -272,13 +268,6 @@ nfsd_prune_bucket_locked(struct nfsd_net *nn, struct nfsd_drc_bucket *b,
 
 	/* The bucket LRU is ordered oldest-first. */
 	list_for_each_entry_safe(rp, tmp, &b->lru_head, c_lru) {
-		/*
-		 * Don't free entries attached to calls that are still
-		 * in-progress, but do keep scanning the list.
-		 */
-		if (rp->c_state == RC_INPROG)
-			continue;
-
 		if (atomic_read(&nn->num_drc_entries) <= nn->max_drc_entries &&
 		    time_before(expiry, rp->c_timestamp))
 			break;
@@ -453,8 +442,6 @@ nfsd_cache_insert(struct nfsd_drc_bucket *b, struct nfsd_cacherep *key,
 				nn->longest_chain_cachesize,
 				atomic_read(&nn->num_drc_entries));
 	}
-
-	lru_put_end(b, ret);
 	return ret;
 }