Initial import

1 files changed, 365 insertions, 0 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
new file mode 100644
index 000000000..df9932b00
--- /dev/null
+++ b/fs/btrfs/async-thread.c
@@ -0,0 +1,365 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ * Copyright (C) 2014 Fujitsu.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/kthread.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/freezer.h>
+#include "async-thread.h"
+#include "ctree.h"
+
+#define WORK_DONE_BIT 0
+#define WORK_ORDER_DONE_BIT 1
+#define WORK_HIGH_PRIO_BIT 2
+
+#define NO_THRESHOLD (-1)
+#define DFT_THRESHOLD (32)
+
+struct __btrfs_workqueue {
+	struct workqueue_struct *normal_wq;
+	/* List head pointing to ordered work list */
+	struct list_head ordered_list;
+
+	/* Spinlock for ordered_list */
+	spinlock_t list_lock;
+
+	/* Thresholding related variants */
+	atomic_t pending;
+	int max_active;
+	int current_max;
+	int thresh;
+	unsigned int count;
+	spinlock_t thres_lock;
+};
+
+struct btrfs_workqueue {
+	struct __btrfs_workqueue *normal;
+	struct __btrfs_workqueue *high;
+};
+
+static void normal_work_helper(struct btrfs_work *work);
+
+#define BTRFS_WORK_HELPER(name)					\
+void btrfs_##name(struct work_struct *arg)				\
+{									\
+	struct btrfs_work *work = container_of(arg, struct btrfs_work,	\
+					       normal_work);		\
+	normal_work_helper(work);					\
+}
+
+BTRFS_WORK_HELPER(worker_helper);
+BTRFS_WORK_HELPER(delalloc_helper);
+BTRFS_WORK_HELPER(flush_delalloc_helper);
+BTRFS_WORK_HELPER(cache_helper);
+BTRFS_WORK_HELPER(submit_helper);
+BTRFS_WORK_HELPER(fixup_helper);
+BTRFS_WORK_HELPER(endio_helper);
+BTRFS_WORK_HELPER(endio_meta_helper);
+BTRFS_WORK_HELPER(endio_meta_write_helper);
+BTRFS_WORK_HELPER(endio_raid56_helper);
+BTRFS_WORK_HELPER(endio_repair_helper);
+BTRFS_WORK_HELPER(rmw_helper);
+BTRFS_WORK_HELPER(endio_write_helper);
+BTRFS_WORK_HELPER(freespace_write_helper);
+BTRFS_WORK_HELPER(delayed_meta_helper);
+BTRFS_WORK_HELPER(readahead_helper);
+BTRFS_WORK_HELPER(qgroup_rescan_helper);
+BTRFS_WORK_HELPER(extent_refs_helper);
+BTRFS_WORK_HELPER(scrub_helper);
+BTRFS_WORK_HELPER(scrubwrc_helper);
+BTRFS_WORK_HELPER(scrubnc_helper);
+
+static struct __btrfs_workqueue *
+__btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active,
+			 int thresh)
+{
+	struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
+
+	if (!ret)
+		return NULL;
+
+	ret->max_active = max_active;
+	atomic_set(&ret->pending, 0);
+	if (thresh == 0)
+		thresh = DFT_THRESHOLD;
+	/* For low threshold, disabling threshold is a better choice */
+	if (thresh < DFT_THRESHOLD) {
+		ret->current_max = max_active;
+		ret->thresh = NO_THRESHOLD;
+	} else {
+		ret->current_max = 1;
+		ret->thresh = thresh;
+	}
+
+	if (flags & WQ_HIGHPRI)
+		ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
+						 ret->max_active,
+						 "btrfs", name);
+	else
+		ret->normal_wq = alloc_workqueue("%s-%s", flags,
+						 ret->max_active, "btrfs",
+						 name);
+	if (!ret->normal_wq) {
+		kfree(ret);
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&ret->ordered_list);
+	spin_lock_init(&ret->list_lock);
+	spin_lock_init(&ret->thres_lock);
+	trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
+	return ret;
+}
+
+static inline void
+__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
+
+struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
+					      unsigned int flags,
+					      int max_active,
+					      int thresh)
+{
+	struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
+
+	if (!ret)
+		return NULL;
+
+	ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
+					      max_active, thresh);
+	if (!ret->normal) {
+		kfree(ret);
+		return NULL;
+	}
+
+	if (flags & WQ_HIGHPRI) {
+		ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
+						    thresh);
+		if (!ret->high) {
+			__btrfs_destroy_workqueue(ret->normal);
+			kfree(ret);
+			return NULL;
+		}
+	}
+	return ret;
+}
+
+/*
+ * Hook for threshold which will be called in btrfs_queue_work.
+ * This hook WILL be called in IRQ handler context,
+ * so workqueue_set_max_active MUST NOT be called in this hook
+ */
+static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
+{
+	if (wq->thresh == NO_THRESHOLD)
+		return;
+	atomic_inc(&wq->pending);
+}
+
+/*
+ * Hook for threshold which will be called before executing the work,
+ * This hook is called in kthread content.
+ * So workqueue_set_max_active is called here.
+ */
+static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
+{
+	int new_max_active;
+	long pending;
+	int need_change = 0;
+
+	if (wq->thresh == NO_THRESHOLD)
+		return;
+
+	atomic_dec(&wq->pending);
+	spin_lock(&wq->thres_lock);
+	/*
+	 * Use wq->count to limit the calling frequency of
+	 * workqueue_set_max_active.
+	 */
+	wq->count++;
+	wq->count %= (wq->thresh / 4);
+	if (!wq->count)
+		goto  out;
+	new_max_active = wq->current_max;
+
+	/*
+	 * pending may be changed later, but it's OK since we really
+	 * don't need it so accurate to calculate new_max_active.
+	 */
+	pending = atomic_read(&wq->pending);
+	if (pending > wq->thresh)
+		new_max_active++;
+	if (pending < wq->thresh / 2)
+		new_max_active--;
+	new_max_active = clamp_val(new_max_active, 1, wq->max_active);
+	if (new_max_active != wq->current_max)  {
+		need_change = 1;
+		wq->current_max = new_max_active;
+	}
+out:
+	spin_unlock(&wq->thres_lock);
+
+	if (need_change) {
+		workqueue_set_max_active(wq->normal_wq, wq->current_max);
+	}
+}
+
+static void run_ordered_work(struct __btrfs_workqueue *wq)
+{
+	struct list_head *list = &wq->ordered_list;
+	struct btrfs_work *work;
+	spinlock_t *lock = &wq->list_lock;
+	unsigned long flags;
+
+	while (1) {
+		spin_lock_irqsave(lock, flags);
+		if (list_empty(list))
+			break;
+		work = list_entry(list->next, struct btrfs_work,
+				  ordered_list);
+		if (!test_bit(WORK_DONE_BIT, &work->flags))
+			break;
+
+		/*
+		 * we are going to call the ordered done function, but
+		 * we leave the work item on the list as a barrier so
+		 * that later work items that are done don't have their
+		 * functions called before this one returns
+		 */
+		if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
+			break;
+		trace_btrfs_ordered_sched(work);
+		spin_unlock_irqrestore(lock, flags);
+		work->ordered_func(work);
+
+		/* now take the lock again and drop our item from the list */
+		spin_lock_irqsave(lock, flags);
+		list_del(&work->ordered_list);
+		spin_unlock_irqrestore(lock, flags);
+
+		/*
+		 * we don't want to call the ordered free functions
+		 * with the lock held though
+		 */
+		work->ordered_free(work);
+		trace_btrfs_all_work_done(work);
+	}
+	spin_unlock_irqrestore(lock, flags);
+}
+
+static void normal_work_helper(struct btrfs_work *work)
+{
+	struct __btrfs_workqueue *wq;
+	int need_order = 0;
+
+	/*
+	 * We should not touch things inside work in the following cases:
+	 * 1) after work->func() if it has no ordered_free
+	 *    Since the struct is freed in work->func().
+	 * 2) after setting WORK_DONE_BIT
+	 *    The work may be freed in other threads almost instantly.
+	 * So we save the needed things here.
+	 */
+	if (work->ordered_func)
+		need_order = 1;
+	wq = work->wq;
+
+	trace_btrfs_work_sched(work);
+	thresh_exec_hook(wq);
+	work->func(work);
+	if (need_order) {
+		set_bit(WORK_DONE_BIT, &work->flags);
+		run_ordered_work(wq);
+	}
+	if (!need_order)
+		trace_btrfs_all_work_done(work);
+}
+
+void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
+		     btrfs_func_t func,
+		     btrfs_func_t ordered_func,
+		     btrfs_func_t ordered_free)
+{
+	work->func = func;
+	work->ordered_func = ordered_func;
+	work->ordered_free = ordered_free;
+	INIT_WORK(&work->normal_work, uniq_func);
+	INIT_LIST_HEAD(&work->ordered_list);
+	work->flags = 0;
+}
+
+static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
+				      struct btrfs_work *work)
+{
+	unsigned long flags;
+
+	work->wq = wq;
+	thresh_queue_hook(wq);
+	if (work->ordered_func) {
+		spin_lock_irqsave(&wq->list_lock, flags);
+		list_add_tail(&work->ordered_list, &wq->ordered_list);
+		spin_unlock_irqrestore(&wq->list_lock, flags);
+	}
+	queue_work(wq->normal_wq, &work->normal_work);
+	trace_btrfs_work_queued(work);
+}
+
+void btrfs_queue_work(struct btrfs_workqueue *wq,
+		      struct btrfs_work *work)
+{
+	struct __btrfs_workqueue *dest_wq;
+
+	if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
+		dest_wq = wq->high;
+	else
+		dest_wq = wq->normal;
+	__btrfs_queue_work(dest_wq, work);
+}
+
+static inline void
+__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
+{
+	destroy_workqueue(wq->normal_wq);
+	trace_btrfs_workqueue_destroy(wq);
+	kfree(wq);
+}
+
+void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
+{
+	if (!wq)
+		return;
+	if (wq->high)
+		__btrfs_destroy_workqueue(wq->high);
+	__btrfs_destroy_workqueue(wq->normal);
+	kfree(wq);
+}
+
+void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
+{
+	if (!wq)
+		return;
+	wq->normal->max_active = max;
+	if (wq->high)
+		wq->high->max_active = max;
+}
+
+void btrfs_set_work_high_priority(struct btrfs_work *work)
+{
+	set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
+}