1 files changed, 95 insertions, 0 deletions

diff --git a/include/linux/slow-work.h b/include/linux/slow-work.h
new file mode 100644
index 000000000000..b65c8881f07a
--- /dev/null
+++ b/include/linux/slow-work.h
@@ -0,0 +1,95 @@
+/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ *
+ * See Documentation/slow-work.txt
+ */
+
+#ifndef _LINUX_SLOW_WORK_H
+#define _LINUX_SLOW_WORK_H
+
+#ifdef CONFIG_SLOW_WORK
+
+#include <linux/sysctl.h>
+
+struct slow_work;
+
+/*
+ * The operations used to support slow work items
+ */
+struct slow_work_ops {
+        /* get a ref on a work item
+         * - return 0 if successful, -ve if not
+         */
+        int (*get_ref)(struct slow_work *work);
+
+        /* discard a ref to a work item */
+        void (*put_ref)(struct slow_work *work);
+
+        /* execute a work item */
+        void (*execute)(struct slow_work *work);
+};
+
+/*
+ * A slow work item
+ * - A reference is held on the parent object by the thread pool when it is
+ *   queued
+ */
+struct slow_work {
+        unsigned long           flags;
+#define SLOW_WORK_PENDING       0       /* item pending (further) execution */
+#define SLOW_WORK_EXECUTING     1       /* item currently executing */
+#define SLOW_WORK_ENQ_DEFERRED  2       /* item enqueue deferred */
+#define SLOW_WORK_VERY_SLOW     3       /* item is very slow */
+        const struct slow_work_ops *ops; /* operations table for this item */
+        struct list_head        link;   /* link in queue */
+};
+
+/**
+ * slow_work_init - Initialise a slow work item
+ * @work: The work item to initialise
+ * @ops: The operations to use to handle the slow work item
+ *
+ * Initialise a slow work item.
+ */
+static inline void slow_work_init(struct slow_work *work,
+                                  const struct slow_work_ops *ops)
+{
+        work->flags = 0;
+        work->ops = ops;
+        INIT_LIST_HEAD(&work->link);
+}
+
+/**
+ * vslow_work_init - Initialise a very slow work item
+ * @work: The work item to initialise
+ * @ops: The operations to use to handle the slow work item
+ *
+ * Initialise a very slow work item.  This item will be restricted such that
+ * only a certain number of the pool threads will be able to execute items of
+ * this type.
+ */
+static inline void vslow_work_init(struct slow_work *work,
+                                   const struct slow_work_ops *ops)
+{
+        work->flags = 1 << SLOW_WORK_VERY_SLOW;
+        work->ops = ops;
+        INIT_LIST_HEAD(&work->link);
+}
+
+extern int slow_work_enqueue(struct slow_work *work);
+extern int slow_work_register_user(void);
+extern void slow_work_unregister_user(void);
+
+#ifdef CONFIG_SYSCTL
+extern ctl_table slow_work_sysctls[];
+#endif
+
+#endif /* CONFIG_SLOW_WORK */
+#endif /* _LINUX_SLOW_WORK_H */