[linux-block.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(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);
	return ret;
}

static inline void
__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);

struct btrfs_workqueue *btrfs_alloc_workqueue(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);
	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);
}

void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
{
	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
0bd9289c	59	__btrfs_alloc_workqueue(char name, int flags, int max_active, int thresh)
1ca08976	60	{
d458b054	61	struct __btrfs_workqueue ret = kzalloc(sizeof(ret), GFP_NOFS);
1ca08976 QW	62
	63	if (unlikely(!ret))
	64	return NULL;
	65
0bd9289c QW	66	ret->max_active = max_active;
	67	atomic_set(&ret->pending, 0);
	68	if (thresh == 0)
	69	thresh = DFT_THRESHOLD;
	70	/* For low threshold, disabling threshold is a better choice */
	71	if (thresh < DFT_THRESHOLD) {
	72	ret->current_max = max_active;
	73	ret->thresh = NO_THRESHOLD;
	74	} else {
	75	ret->current_max = 1;
	76	ret->thresh = thresh;
	77	}
	78
1ca08976 QW	79	if (flags & WQ_HIGHPRI)
1ca08976 QW	80	ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
0bd9289c QW	81	ret->max_active,
0bd9289c QW	82	"btrfs", name);
1ca08976 QW	83	else
1ca08976 QW	84	ret->normal_wq = alloc_workqueue("%s-%s", flags,
0bd9289c QW	85	ret->max_active, "btrfs",
0bd9289c QW	86	name);
1ca08976 QW	87	if (unlikely(!ret->normal_wq)) {
	88	kfree(ret);
	89	return NULL;
	90	}
	91
	92	INIT_LIST_HEAD(&ret->ordered_list);
	93	spin_lock_init(&ret->list_lock);
0bd9289c	94	spin_lock_init(&ret->thres_lock);
1ca08976 QW	95	return ret;
	96	}
	97
	98	static inline void
d458b054	99	__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
1ca08976	100
d458b054 QW	101	struct btrfs_workqueue btrfs_alloc_workqueue(char name,
	102	int flags,
	103	int max_active,
	104	int thresh)
08a9ff32	105	{
d458b054	106	struct btrfs_workqueue ret = kzalloc(sizeof(ret), GFP_NOFS);
08a9ff32 QW	107
	108	if (unlikely(!ret))
	109	return NULL;
	110
1ca08976	111	ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
0bd9289c	112	max_active, thresh);
1ca08976	113	if (unlikely(!ret->normal)) {
08a9ff32 QW	114	kfree(ret);
	115	return NULL;
	116	}
	117
1ca08976	118	if (flags & WQ_HIGHPRI) {
0bd9289c QW	119	ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
0bd9289c QW	120	thresh);
1ca08976 QW	121	if (unlikely(!ret->high)) {
	122	__btrfs_destroy_workqueue(ret->normal);
	123	kfree(ret);
	124	return NULL;
	125	}
	126	}
08a9ff32 QW	127	return ret;
	128	}
	129
0bd9289c QW	130	/*
	131	* Hook for threshold which will be called in btrfs_queue_work.
	132	* This hook WILL be called in IRQ handler context,
	133	* so workqueue_set_max_active MUST NOT be called in this hook
	134	*/
d458b054	135	static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
0bd9289c QW	136	{
	137	if (wq->thresh == NO_THRESHOLD)
	138	return;
	139	atomic_inc(&wq->pending);
	140	}
	141
	142	/*
	143	* Hook for threshold which will be called before executing the work,
	144	* This hook is called in kthread content.
	145	* So workqueue_set_max_active is called here.
	146	*/
d458b054	147	static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
0bd9289c QW	148	{
	149	int new_max_active;
	150	long pending;
	151	int need_change = 0;
	152
	153	if (wq->thresh == NO_THRESHOLD)
	154	return;
	155
	156	atomic_dec(&wq->pending);
	157	spin_lock(&wq->thres_lock);
	158	/*
	159	* Use wq->count to limit the calling frequency of
	160	* workqueue_set_max_active.
	161	*/
	162	wq->count++;
	163	wq->count %= (wq->thresh / 4);
	164	if (!wq->count)
	165	goto out;
	166	new_max_active = wq->current_max;
	167
	168	/*
	169	* pending may be changed later, but it's OK since we really
	170	* don't need it so accurate to calculate new_max_active.
	171	*/
	172	pending = atomic_read(&wq->pending);
	173	if (pending > wq->thresh)
	174	new_max_active++;
	175	if (pending < wq->thresh / 2)
	176	new_max_active--;
	177	new_max_active = clamp_val(new_max_active, 1, wq->max_active);
	178	if (new_max_active != wq->current_max) {
	179	need_change = 1;
	180	wq->current_max = new_max_active;
	181	}
	182	out:
	183	spin_unlock(&wq->thres_lock);
	184
	185	if (need_change) {
	186	workqueue_set_max_active(wq->normal_wq, wq->current_max);
	187	}
	188	}
	189
d458b054	190	static void run_ordered_work(struct __btrfs_workqueue *wq)
08a9ff32 QW	191	{
08a9ff32 QW	192	struct list_head *list = &wq->ordered_list;
d458b054	193	struct btrfs_work *work;
08a9ff32 QW	194	spinlock_t *lock = &wq->list_lock;
	195	unsigned long flags;
	196
	197	while (1) {
	198	spin_lock_irqsave(lock, flags);
	199	if (list_empty(list))
	200	break;
d458b054	201	work = list_entry(list->next, struct btrfs_work,
08a9ff32 QW	202	ordered_list);
	203	if (!test_bit(WORK_DONE_BIT, &work->flags))
	204	break;
	205
	206	/*
	207	* we are going to call the ordered done function, but
	208	* we leave the work item on the list as a barrier so
	209	* that later work items that are done don't have their
	210	* functions called before this one returns
	211	*/
	212	if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
	213	break;
52483bc2	214	trace_btrfs_ordered_sched(work);
08a9ff32 QW	215	spin_unlock_irqrestore(lock, flags);
	216	work->ordered_func(work);
	217
	218	/* now take the lock again and drop our item from the list */
	219	spin_lock_irqsave(lock, flags);
	220	list_del(&work->ordered_list);
	221	spin_unlock_irqrestore(lock, flags);
	222
	223	/*
	224	* we don't want to call the ordered free functions
	225	* with the lock held though
	226	*/
	227	work->ordered_free(work);
52483bc2	228	trace_btrfs_all_work_done(work);
08a9ff32 QW	229	}
	230	spin_unlock_irqrestore(lock, flags);
	231	}
	232
	233	static void normal_work_helper(struct work_struct *arg)
	234	{
d458b054 QW	235	struct btrfs_work *work;
d458b054 QW	236	struct __btrfs_workqueue *wq;
08a9ff32 QW	237	int need_order = 0;
08a9ff32 QW	238
d458b054	239	work = container_of(arg, struct btrfs_work, normal_work);
08a9ff32 QW	240	/*
	241	* We should not touch things inside work in the following cases:
	242	* 1) after work->func() if it has no ordered_free
	243	* Since the struct is freed in work->func().
	244	* 2) after setting WORK_DONE_BIT
	245	* The work may be freed in other threads almost instantly.
	246	* So we save the needed things here.
	247	*/
	248	if (work->ordered_func)
	249	need_order = 1;
	250	wq = work->wq;
	251
52483bc2	252	trace_btrfs_work_sched(work);
0bd9289c	253	thresh_exec_hook(wq);
08a9ff32 QW	254	work->func(work);
	255	if (need_order) {
	256	set_bit(WORK_DONE_BIT, &work->flags);
	257	run_ordered_work(wq);
	258	}
52483bc2 QW	259	if (!need_order)
52483bc2 QW	260	trace_btrfs_all_work_done(work);
08a9ff32 QW	261	}
08a9ff32 QW	262
d458b054	263	void btrfs_init_work(struct btrfs_work *work,
6db8914f QW	264	btrfs_func_t func,
	265	btrfs_func_t ordered_func,
	266	btrfs_func_t ordered_free)
08a9ff32 QW	267	{
	268	work->func = func;
	269	work->ordered_func = ordered_func;
	270	work->ordered_free = ordered_free;
	271	INIT_WORK(&work->normal_work, normal_work_helper);
	272	INIT_LIST_HEAD(&work->ordered_list);
	273	work->flags = 0;
	274	}
	275
d458b054 QW	276	static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
d458b054 QW	277	struct btrfs_work *work)
08a9ff32 QW	278	{
	279	unsigned long flags;
	280
	281	work->wq = wq;
0bd9289c	282	thresh_queue_hook(wq);
08a9ff32 QW	283	if (work->ordered_func) {
	284	spin_lock_irqsave(&wq->list_lock, flags);
	285	list_add_tail(&work->ordered_list, &wq->ordered_list);
	286	spin_unlock_irqrestore(&wq->list_lock, flags);
	287	}
	288	queue_work(wq->normal_wq, &work->normal_work);
52483bc2	289	trace_btrfs_work_queued(work);
08a9ff32 QW	290	}
08a9ff32 QW	291
d458b054 QW	292	void btrfs_queue_work(struct btrfs_workqueue *wq,
d458b054 QW	293	struct btrfs_work *work)
1ca08976	294	{
d458b054	295	struct __btrfs_workqueue *dest_wq;
1ca08976 QW	296
	297	if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
	298	dest_wq = wq->high;
	299	else
	300	dest_wq = wq->normal;
	301	__btrfs_queue_work(dest_wq, work);
	302	}
	303
	304	static inline void
d458b054	305	__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
08a9ff32 QW	306	{
	307	destroy_workqueue(wq->normal_wq);
	308	kfree(wq);
	309	}
	310
d458b054	311	void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
1ca08976 QW	312	{
	313	if (!wq)
	314	return;
	315	if (wq->high)
	316	__btrfs_destroy_workqueue(wq->high);
	317	__btrfs_destroy_workqueue(wq->normal);
	318	}
	319
d458b054	320	void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
08a9ff32	321	{
0bd9289c	322	wq->normal->max_active = max;
1ca08976	323	if (wq->high)
0bd9289c	324	wq->high->max_active = max;
1ca08976 QW	325	}
1ca08976 QW	326
d458b054	327	void btrfs_set_work_high_priority(struct btrfs_work *work)
1ca08976 QW	328	{
1ca08976 QW	329	set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
08a9ff32	330	}