1 files changed, 348 insertions, 0 deletions

diff --git a/drivers/md/bcache/closure.c b/drivers/md/bcache/closure.c
new file mode 100644
index 000000000000..d6fbec0f8484
--- /dev/null
+++ b/drivers/md/bcache/closure.c
@@ -0,0 +1,348 @@
+/*
+ * Asynchronous refcounty things
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+
+#include "closure.h"
+
+void closure_queue(struct closure *cl)
+{
+        struct workqueue_struct *wq = cl->wq;
+        if (wq) {
+                INIT_WORK(&cl->work, cl->work.func);
+                BUG_ON(!queue_work(wq, &cl->work));
+        } else
+                cl->fn(cl);
+}
+EXPORT_SYMBOL_GPL(closure_queue);
+
+#define CL_FIELD(type, field)                                   \
+        case TYPE_ ## type:                                     \
+        return &container_of(cl, struct type, cl)->field
+
+static struct closure_waitlist *closure_waitlist(struct closure *cl)
+{
+        switch (cl->type) {
+                CL_FIELD(closure_with_waitlist, wait);
+                CL_FIELD(closure_with_waitlist_and_timer, wait);
+        default:
+                return NULL;
+        }
+}
+
+static struct timer_list *closure_timer(struct closure *cl)
+{
+        switch (cl->type) {
+                CL_FIELD(closure_with_timer, timer);
+                CL_FIELD(closure_with_waitlist_and_timer, timer);
+        default:
+                return NULL;
+        }
+}
+
+static inline void closure_put_after_sub(struct closure *cl, int flags)
+{
+        int r = flags & CLOSURE_REMAINING_MASK;
+
+        BUG_ON(flags & CLOSURE_GUARD_MASK);
+        BUG_ON(!r && (flags & ~(CLOSURE_DESTRUCTOR|CLOSURE_BLOCKING)));
+
+        /* Must deliver precisely one wakeup */
+        if (r == 1 && (flags & CLOSURE_SLEEPING))
+                wake_up_process(cl->task);
+
+        if (!r) {
+                if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
+                        /* CLOSURE_BLOCKING might be set - clear it */
+                        atomic_set(&cl->remaining,
+                                   CLOSURE_REMAINING_INITIALIZER);
+                        closure_queue(cl);
+                } else {
+                        struct closure *parent = cl->parent;
+                        struct closure_waitlist *wait = closure_waitlist(cl);
+
+                        closure_debug_destroy(cl);
+
+                        atomic_set(&cl->remaining, -1);
+
+                        if (wait)
+                                closure_wake_up(wait);
+
+                        if (cl->fn)
+                                cl->fn(cl);
+
+                        if (parent)
+                                closure_put(parent);
+                }
+        }
+}
+
+/* For clearing flags with the same atomic op as a put */
+void closure_sub(struct closure *cl, int v)
+{
+        closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
+}
+EXPORT_SYMBOL_GPL(closure_sub);
+
+void closure_put(struct closure *cl)
+{
+        closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
+}
+EXPORT_SYMBOL_GPL(closure_put);
+
+static void set_waiting(struct closure *cl, unsigned long f)
+{
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+        cl->waiting_on = f;
+#endif
+}
+
+void __closure_wake_up(struct closure_waitlist *wait_list)
+{
+        struct llist_node *list;
+        struct closure *cl;
+        struct llist_node *reverse = NULL;
+
+        list = llist_del_all(&wait_list->list);
+
+        /* We first reverse the list to preserve FIFO ordering and fairness */
+
+        while (list) {
+                struct llist_node *t = list;
+                list = llist_next(list);
+
+                t->next = reverse;
+                reverse = t;
+        }
+
+        /* Then do the wakeups */
+
+        while (reverse) {
+                cl = container_of(reverse, struct closure, list);
+                reverse = llist_next(reverse);
+
+                set_waiting(cl, 0);
+                closure_sub(cl, CLOSURE_WAITING + 1);
+        }
+}
+EXPORT_SYMBOL_GPL(__closure_wake_up);
+
+bool closure_wait(struct closure_waitlist *list, struct closure *cl)
+{
+        if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
+                return false;
+
+        set_waiting(cl, _RET_IP_);
+        atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
+        llist_add(&cl->list, &list->list);
+
+        return true;
+}
+EXPORT_SYMBOL_GPL(closure_wait);
+
+/**
+ * closure_sync() - sleep until a closure a closure has nothing left to wait on
+ *
+ * Sleeps until the refcount hits 1 - the thread that's running the closure owns
+ * the last refcount.
+ */
+void closure_sync(struct closure *cl)
+{
+        while (1) {
+                __closure_start_sleep(cl);
+                closure_set_ret_ip(cl);
+
+                if ((atomic_read(&cl->remaining) &
+                     CLOSURE_REMAINING_MASK) == 1)
+                        break;
+
+                schedule();
+        }
+
+        __closure_end_sleep(cl);
+}
+EXPORT_SYMBOL_GPL(closure_sync);
+
+/**
+ * closure_trylock() - try to acquire the closure, without waiting
+ * @cl:         closure to lock
+ *
+ * Returns true if the closure was succesfully locked.
+ */
+bool closure_trylock(struct closure *cl, struct closure *parent)
+{
+        if (atomic_cmpxchg(&cl->remaining, -1,
+                           CLOSURE_REMAINING_INITIALIZER) != -1)
+                return false;
+
+        closure_set_ret_ip(cl);
+
+        smp_mb();
+        cl->parent = parent;
+        if (parent)
+                closure_get(parent);
+
+        closure_debug_create(cl);
+        return true;
+}
+EXPORT_SYMBOL_GPL(closure_trylock);
+
+void __closure_lock(struct closure *cl, struct closure *parent,
+                    struct closure_waitlist *wait_list)
+{
+        struct closure wait;
+        closure_init_stack(&wait);
+
+        while (1) {
+                if (closure_trylock(cl, parent))
+                        return;
+
+                closure_wait_event_sync(wait_list, &wait,
+                                        atomic_read(&cl->remaining) == -1);
+        }
+}
+EXPORT_SYMBOL_GPL(__closure_lock);
+
+static void closure_delay_timer_fn(unsigned long data)
+{
+        struct closure *cl = (struct closure *) data;
+        closure_sub(cl, CLOSURE_TIMER + 1);
+}
+
+void do_closure_timer_init(struct closure *cl)
+{
+        struct timer_list *timer = closure_timer(cl);
+
+        init_timer(timer);
+        timer->data     = (unsigned long) cl;
+        timer->function = closure_delay_timer_fn;
+}
+EXPORT_SYMBOL_GPL(do_closure_timer_init);
+
+bool __closure_delay(struct closure *cl, unsigned long delay,
+                     struct timer_list *timer)
+{
+        if (atomic_read(&cl->remaining) & CLOSURE_TIMER)
+                return false;
+
+        BUG_ON(timer_pending(timer));
+
+        timer->expires  = jiffies + delay;
+
+        atomic_add(CLOSURE_TIMER + 1, &cl->remaining);
+        add_timer(timer);
+        return true;
+}
+EXPORT_SYMBOL_GPL(__closure_delay);
+
+void __closure_flush(struct closure *cl, struct timer_list *timer)
+{
+        if (del_timer(timer))
+                closure_sub(cl, CLOSURE_TIMER + 1);
+}
+EXPORT_SYMBOL_GPL(__closure_flush);
+
+void __closure_flush_sync(struct closure *cl, struct timer_list *timer)
+{
+        if (del_timer_sync(timer))
+                closure_sub(cl, CLOSURE_TIMER + 1);
+}
+EXPORT_SYMBOL_GPL(__closure_flush_sync);
+
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+
+static LIST_HEAD(closure_list);
+static DEFINE_SPINLOCK(closure_list_lock);
+
+void closure_debug_create(struct closure *cl)
+{
+        unsigned long flags;
+
+        BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
+        cl->magic = CLOSURE_MAGIC_ALIVE;
+
+        spin_lock_irqsave(&closure_list_lock, flags);
+        list_add(&cl->all, &closure_list);
+        spin_unlock_irqrestore(&closure_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(closure_debug_create);
+
+void closure_debug_destroy(struct closure *cl)
+{
+        unsigned long flags;
+
+        BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
+        cl->magic = CLOSURE_MAGIC_DEAD;
+
+        spin_lock_irqsave(&closure_list_lock, flags);
+        list_del(&cl->all);
+        spin_unlock_irqrestore(&closure_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(closure_debug_destroy);
+
+static struct dentry *debug;
+
+#define work_data_bits(work) ((unsigned long *)(&(work)->data))
+
+static int debug_seq_show(struct seq_file *f, void *data)
+{
+        struct closure *cl;
+        spin_lock_irq(&closure_list_lock);
+
+        list_for_each_entry(cl, &closure_list, all) {
+                int r = atomic_read(&cl->remaining);
+
+                seq_printf(f, "%p: %pF -> %pf p %p r %i ",
+                           cl, (void *) cl->ip, cl->fn, cl->parent,
+                           r & CLOSURE_REMAINING_MASK);
+
+                seq_printf(f, "%s%s%s%s%s%s\n",
+                           test_bit(WORK_STRUCT_PENDING,
+                                    work_data_bits(&cl->work)) ? "Q" : "",
+                           r & CLOSURE_RUNNING  ? "R" : "",
+                           r & CLOSURE_BLOCKING ? "B" : "",
+                           r & CLOSURE_STACK    ? "S" : "",
+                           r & CLOSURE_SLEEPING ? "Sl" : "",
+                           r & CLOSURE_TIMER    ? "T" : "");
+
+                if (r & CLOSURE_WAITING)
+                        seq_printf(f, " W %pF\n",
+                                   (void *) cl->waiting_on);
+
+                seq_printf(f, "\n");
+        }
+
+        spin_unlock_irq(&closure_list_lock);
+        return 0;
+}
+
+static int debug_seq_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, debug_seq_show, NULL);
+}
+
+static const struct file_operations debug_ops = {
+        .owner          = THIS_MODULE,
+        .open           = debug_seq_open,
+        .read           = seq_read,
+        .release        = single_release
+};
+
+int __init closure_debug_init(void)
+{
+        debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
+        return 0;
+}
+
+module_init(closure_debug_init);
+
+#endif
+
+MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
+MODULE_LICENSE("GPL");