[mirror_ubuntu-artful-kernel.git] / fs / btrfs / async-thread.c

/*
 * 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 <linux/workqueue.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 inline struct __btrfs_workqueue
*__btrfs_alloc_workqueue(const char *name, int flags, int max_active,
			 int thresh)
{
	struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);

	if (unlikely(!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 (unlikely(!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,
					      int flags,
					      int max_active,
					      int thresh)
{
	struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);

	if (unlikely(!ret))
		return NULL;

	ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
					      max_active, thresh);
	if (unlikely(!ret->normal)) {
		kfree(ret);
		return NULL;
	}

	if (flags & WQ_HIGHPRI) {
		ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
						    thresh);
		if (unlikely(!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 work_struct *arg)
{
	struct btrfs_work *work;
	struct __btrfs_workqueue *wq;
	int need_order = 0;

	work = container_of(arg, struct btrfs_work, normal_work);
	/*
	 * 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_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, normal_work_helper);
	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);
}
Commit	Line	Data
8b712842 CM	1	/*
8b712842 CM	2	* Copyright (C) 2007 Oracle. All rights reserved.
08a9ff32	3	* Copyright (C) 2014 Fujitsu. All rights reserved.
8b712842 CM	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public
	7	* License v2 as published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	12	* General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public
	15	* License along with this program; if not, write to the
	16	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	17	* Boston, MA 021110-1307, USA.
	18	*/
	19
	20	#include <linux/kthread.h>
5a0e3ad6	21	#include <linux/slab.h>
8b712842 CM	22	#include <linux/list.h>
8b712842 CM	23	#include <linux/spinlock.h>
b51912c9	24	#include <linux/freezer.h>
08a9ff32	25	#include <linux/workqueue.h>
8b712842	26	#include "async-thread.h"
52483bc2	27	#include "ctree.h"
8b712842	28
a046e9c8 QW	29	#define WORK_DONE_BIT 0
	30	#define WORK_ORDER_DONE_BIT 1
	31	#define WORK_HIGH_PRIO_BIT 2
4a69a410	32
0bd9289c QW	33	#define NO_THRESHOLD (-1)
	34	#define DFT_THRESHOLD (32)
	35
d458b054	36	struct __btrfs_workqueue {
08a9ff32 QW	37	struct workqueue_struct *normal_wq;
	38	/* List head pointing to ordered work list */
	39	struct list_head ordered_list;
	40
	41	/* Spinlock for ordered_list */
	42	spinlock_t list_lock;
0bd9289c QW	43
	44	/* Thresholding related variants */
	45	atomic_t pending;
	46	int max_active;
	47	int current_max;
	48	int thresh;
	49	unsigned int count;
	50	spinlock_t thres_lock;
08a9ff32 QW	51	};
08a9ff32 QW	52
d458b054 QW	53	struct btrfs_workqueue {
	54	struct __btrfs_workqueue *normal;
	55	struct __btrfs_workqueue *high;
1ca08976 QW	56	};
1ca08976 QW	57
d458b054	58	static inline struct __btrfs_workqueue
c3a46891 QW	59	__btrfs_alloc_workqueue(const char name, int flags, int max_active,
c3a46891 QW	60	int thresh)
1ca08976	61	{
d458b054	62	struct __btrfs_workqueue ret = kzalloc(sizeof(ret), GFP_NOFS);
1ca08976 QW	63
	64	if (unlikely(!ret))
	65	return NULL;
	66
0bd9289c QW	67	ret->max_active = max_active;
	68	atomic_set(&ret->pending, 0);
	69	if (thresh == 0)
	70	thresh = DFT_THRESHOLD;
	71	/* For low threshold, disabling threshold is a better choice */
	72	if (thresh < DFT_THRESHOLD) {
	73	ret->current_max = max_active;
	74	ret->thresh = NO_THRESHOLD;
	75	} else {
	76	ret->current_max = 1;
	77	ret->thresh = thresh;
	78	}
	79
1ca08976 QW	80	if (flags & WQ_HIGHPRI)
1ca08976 QW	81	ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
0bd9289c QW	82	ret->max_active,
0bd9289c QW	83	"btrfs", name);
1ca08976 QW	84	else
1ca08976 QW	85	ret->normal_wq = alloc_workqueue("%s-%s", flags,
0bd9289c QW	86	ret->max_active, "btrfs",
0bd9289c QW	87	name);
1ca08976 QW	88	if (unlikely(!ret->normal_wq)) {
	89	kfree(ret);
	90	return NULL;
	91	}
	92
	93	INIT_LIST_HEAD(&ret->ordered_list);
	94	spin_lock_init(&ret->list_lock);
0bd9289c	95	spin_lock_init(&ret->thres_lock);
c3a46891	96	trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
1ca08976 QW	97	return ret;
	98	}
	99
	100	static inline void
d458b054	101	__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
1ca08976	102
c3a46891	103	struct btrfs_workqueue btrfs_alloc_workqueue(const char name,
d458b054 QW	104	int flags,
	105	int max_active,
	106	int thresh)
08a9ff32	107	{
d458b054	108	struct btrfs_workqueue ret = kzalloc(sizeof(ret), GFP_NOFS);
08a9ff32 QW	109
	110	if (unlikely(!ret))
	111	return NULL;
	112
1ca08976	113	ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
0bd9289c	114	max_active, thresh);
1ca08976	115	if (unlikely(!ret->normal)) {
08a9ff32 QW	116	kfree(ret);
	117	return NULL;
	118	}
	119
1ca08976	120	if (flags & WQ_HIGHPRI) {
0bd9289c QW	121	ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
0bd9289c QW	122	thresh);
1ca08976 QW	123	if (unlikely(!ret->high)) {
	124	__btrfs_destroy_workqueue(ret->normal);
	125	kfree(ret);
	126	return NULL;
	127	}
	128	}
08a9ff32 QW	129	return ret;
	130	}
	131
0bd9289c QW	132	/*
	133	* Hook for threshold which will be called in btrfs_queue_work.
	134	* This hook WILL be called in IRQ handler context,
	135	* so workqueue_set_max_active MUST NOT be called in this hook
	136	*/
d458b054	137	static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
0bd9289c QW	138	{
	139	if (wq->thresh == NO_THRESHOLD)
	140	return;
	141	atomic_inc(&wq->pending);
	142	}
	143
	144	/*
	145	* Hook for threshold which will be called before executing the work,
	146	* This hook is called in kthread content.
	147	* So workqueue_set_max_active is called here.
	148	*/
d458b054	149	static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
0bd9289c QW	150	{
	151	int new_max_active;
	152	long pending;
	153	int need_change = 0;
	154
	155	if (wq->thresh == NO_THRESHOLD)
	156	return;
	157
	158	atomic_dec(&wq->pending);
	159	spin_lock(&wq->thres_lock);
	160	/*
	161	* Use wq->count to limit the calling frequency of
	162	* workqueue_set_max_active.
	163	*/
	164	wq->count++;
	165	wq->count %= (wq->thresh / 4);
	166	if (!wq->count)
	167	goto out;
	168	new_max_active = wq->current_max;
	169
	170	/*
	171	* pending may be changed later, but it's OK since we really
	172	* don't need it so accurate to calculate new_max_active.
	173	*/
	174	pending = atomic_read(&wq->pending);
	175	if (pending > wq->thresh)
	176	new_max_active++;
	177	if (pending < wq->thresh / 2)
	178	new_max_active--;
	179	new_max_active = clamp_val(new_max_active, 1, wq->max_active);
	180	if (new_max_active != wq->current_max) {
	181	need_change = 1;
	182	wq->current_max = new_max_active;
	183	}
	184	out:
	185	spin_unlock(&wq->thres_lock);
	186
	187	if (need_change) {
	188	workqueue_set_max_active(wq->normal_wq, wq->current_max);
	189	}
	190	}
	191
d458b054	192	static void run_ordered_work(struct __btrfs_workqueue *wq)
08a9ff32 QW	193	{
08a9ff32 QW	194	struct list_head *list = &wq->ordered_list;
d458b054	195	struct btrfs_work *work;
08a9ff32 QW	196	spinlock_t *lock = &wq->list_lock;
	197	unsigned long flags;
	198
	199	while (1) {
	200	spin_lock_irqsave(lock, flags);
	201	if (list_empty(list))
	202	break;
d458b054	203	work = list_entry(list->next, struct btrfs_work,
08a9ff32 QW	204	ordered_list);
	205	if (!test_bit(WORK_DONE_BIT, &work->flags))
	206	break;
	207
	208	/*
	209	* we are going to call the ordered done function, but
	210	* we leave the work item on the list as a barrier so
	211	* that later work items that are done don't have their
	212	* functions called before this one returns
	213	*/
	214	if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
	215	break;
52483bc2	216	trace_btrfs_ordered_sched(work);
08a9ff32 QW	217	spin_unlock_irqrestore(lock, flags);
	218	work->ordered_func(work);
	219
	220	/* now take the lock again and drop our item from the list */
	221	spin_lock_irqsave(lock, flags);
	222	list_del(&work->ordered_list);
	223	spin_unlock_irqrestore(lock, flags);
	224
	225	/*
	226	* we don't want to call the ordered free functions
	227	* with the lock held though
	228	*/
	229	work->ordered_free(work);
52483bc2	230	trace_btrfs_all_work_done(work);
08a9ff32 QW	231	}
	232	spin_unlock_irqrestore(lock, flags);
	233	}
	234
	235	static void normal_work_helper(struct work_struct *arg)
	236	{
d458b054 QW	237	struct btrfs_work *work;
d458b054 QW	238	struct __btrfs_workqueue *wq;
08a9ff32 QW	239	int need_order = 0;
08a9ff32 QW	240
d458b054	241	work = container_of(arg, struct btrfs_work, normal_work);
08a9ff32 QW	242	/*
	243	* We should not touch things inside work in the following cases:
	244	* 1) after work->func() if it has no ordered_free
	245	* Since the struct is freed in work->func().
	246	* 2) after setting WORK_DONE_BIT
	247	* The work may be freed in other threads almost instantly.
	248	* So we save the needed things here.
	249	*/
	250	if (work->ordered_func)
	251	need_order = 1;
	252	wq = work->wq;
	253
52483bc2	254	trace_btrfs_work_sched(work);
0bd9289c	255	thresh_exec_hook(wq);
08a9ff32 QW	256	work->func(work);
	257	if (need_order) {
	258	set_bit(WORK_DONE_BIT, &work->flags);
	259	run_ordered_work(wq);
	260	}
52483bc2 QW	261	if (!need_order)
52483bc2 QW	262	trace_btrfs_all_work_done(work);
08a9ff32 QW	263	}
08a9ff32 QW	264
d458b054	265	void btrfs_init_work(struct btrfs_work *work,
6db8914f QW	266	btrfs_func_t func,
	267	btrfs_func_t ordered_func,
	268	btrfs_func_t ordered_free)
08a9ff32 QW	269	{
	270	work->func = func;
	271	work->ordered_func = ordered_func;
	272	work->ordered_free = ordered_free;
	273	INIT_WORK(&work->normal_work, normal_work_helper);
	274	INIT_LIST_HEAD(&work->ordered_list);
	275	work->flags = 0;
	276	}
	277
d458b054 QW	278	static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
d458b054 QW	279	struct btrfs_work *work)
08a9ff32 QW	280	{
	281	unsigned long flags;
	282
	283	work->wq = wq;
0bd9289c	284	thresh_queue_hook(wq);
08a9ff32 QW	285	if (work->ordered_func) {
	286	spin_lock_irqsave(&wq->list_lock, flags);
	287	list_add_tail(&work->ordered_list, &wq->ordered_list);
	288	spin_unlock_irqrestore(&wq->list_lock, flags);
	289	}
	290	queue_work(wq->normal_wq, &work->normal_work);
52483bc2	291	trace_btrfs_work_queued(work);
08a9ff32 QW	292	}
08a9ff32 QW	293
d458b054 QW	294	void btrfs_queue_work(struct btrfs_workqueue *wq,
d458b054 QW	295	struct btrfs_work *work)
1ca08976	296	{
d458b054	297	struct __btrfs_workqueue *dest_wq;
1ca08976 QW	298
	299	if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
	300	dest_wq = wq->high;
	301	else
	302	dest_wq = wq->normal;
	303	__btrfs_queue_work(dest_wq, work);
	304	}
	305
	306	static inline void
d458b054	307	__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
08a9ff32 QW	308	{
08a9ff32 QW	309	destroy_workqueue(wq->normal_wq);
c3a46891	310	trace_btrfs_workqueue_destroy(wq);
08a9ff32 QW	311	kfree(wq);
	312	}
	313
d458b054	314	void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
1ca08976 QW	315	{
	316	if (!wq)
	317	return;
	318	if (wq->high)
	319	__btrfs_destroy_workqueue(wq->high);
	320	__btrfs_destroy_workqueue(wq->normal);
ef66af10	321	kfree(wq);
1ca08976 QW	322	}
1ca08976 QW	323
d458b054	324	void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
08a9ff32	325	{
800ee224 ST	326	if (!wq)
800ee224 ST	327	return;
0bd9289c	328	wq->normal->max_active = max;
1ca08976	329	if (wq->high)
0bd9289c	330	wq->high->max_active = max;
1ca08976 QW	331	}
1ca08976 QW	332
d458b054	333	void btrfs_set_work_high_priority(struct btrfs_work *work)
1ca08976 QW	334	{
1ca08976 QW	335	set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
08a9ff32	336	}