[PATCH] Use schedule_work to regular cache cleaning

Cleaning of the export caches is currently done by idle
nfsd threads which isn't very reliable.

This patch makes use of work_queues to do it all inside
cache.c

fs/nfsd/nfssvc.c

@@ -209,8 +209,8 @@ nfsd(struct svc_rqst *rqstp)
 		 * recvfrom routine.
 		 */
 		while ((err = svc_recv(serv, rqstp,
-				       5*60*HZ)) == -EAGAIN)
-			cache_clean();
+				       60*60*HZ)) == -EAGAIN)
+			;
 		if (err < 0)
 			break;
 		update_thread_usage(atomic_read(&nfsd_busy));

net/sunrpc/cache.c

@@ -25,6 +25,7 @@
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
 #include <linux/net.h>
+#include <linux/workqueue.h>
 #include <asm/ioctls.h>
 #include <linux/sunrpc/types.h>
 #include <linux/sunrpc/cache.h>
@@ -165,6 +166,9 @@ static struct file_operations cache_file_operations;
 static struct file_operations content_file_operations;
 static struct file_operations cache_flush_operations;
 
+static void do_cache_clean(void *data);
+static DECLARE_WORK(cache_cleaner, do_cache_clean, NULL);
+
 void cache_register(struct cache_detail *cd)
 {
 	cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
@@ -208,6 +212,9 @@ void cache_register(struct cache_detail *cd)
 	cd->last_close = 0;
 	list_add(&cd->others, &cache_list);
 	spin_unlock(&cache_list_lock);
+
+	/* start the cleaning process */
+	schedule_work(&cache_cleaner);
 }
 
 int cache_unregister(struct cache_detail *cd)
@@ -229,6 +236,11 @@ int cache_unregister(struct cache_detail *cd)
 		cd->proc_ent = NULL;
 		remove_proc_entry(cd->name, proc_net_rpc);
 	}
+	if (list_empty(&cache_list)) {
+		/* module must be being unloaded so its safe to kill the worker */
+		cancel_delayed_work(&cache_cleaner);
+		flush_scheduled_work();
+	}
 	return 0;
 }
 
@@ -341,6 +353,23 @@ int cache_clean(void)
 	return rv;
 }
 
+/*
+ * We want to regularly clean the cache, so we need to schedule some work ...
+ */
+static void do_cache_clean(void *data)
+{
+	int delay = 5;
+	if (cache_clean() == -1)
+		delay = 30*HZ;
+
+	if (list_empty(&cache_list))
+		delay = 0;
+
+	if (delay)
+		schedule_delayed_work(&cache_cleaner, delay);
+}
+
+
 /* 
  * Clean all caches promptly.  This just calls cache_clean
  * repeatedly until we are sure that every cache has had a chance to