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Commit c6dd6ea5 authored by Qu Wenruo's avatar Qu Wenruo Committed by Chris Mason
Browse files

btrfs: async_thread: Fix workqueue 'max_active' value when initializing 



At initializing time, for threshold-able workqueue, it's max_active
of kernel workqueue should be 1 and grow if it hits threshold.

But due to the bad naming, there is both 'max_active' for kernel
workqueue and btrfs workqueue.
So wrong value is given at workqueue initialization.

This patch fixes it, and to avoid further misunderstanding, change the
member name of btrfs_workqueue to 'current_active' and 'limit_active'.

Also corresponding comment is added for readability.

Reported-by: default avatarAlex Lyakas <alex.btrfs@zadarastorage.com>
Signed-off-by: default avatarQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 943c6e99

fs/btrfs/async-thread.c

+34 −23
Original line number Diff line number Diff line
@@ -42,8 +42,14 @@ struct __btrfs_workqueue { 


	/* Thresholding related variants */

	atomic_t pending;

	int max_active;

	int current_max;



	/* Up limit of concurrency workers */

	int limit_active;



	/* Current number of concurrency workers */

	int current_active;



	/* Threshold to change current_active */

	int thresh;

	unsigned int count;

	spinlock_t thres_lock;
@@ -88,7 +94,7 @@ BTRFS_WORK_HELPER(scrubnc_helper); 
BTRFS_WORK_HELPER(scrubparity_helper);



static struct __btrfs_workqueue *

__btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active,

__btrfs_alloc_workqueue(const char *name, unsigned int flags, int limit_active,

			 int thresh)

{

	struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
@@ -96,26 +102,31 @@ __btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active, 
	if (!ret)

		return NULL;



	ret->max_active = max_active;

	ret->limit_active = limit_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->current_active = limit_active;

		ret->thresh = NO_THRESHOLD;

	} else {

		ret->current_max = 1;

		/*

		 * For threshold-able wq, let its concurrency grow on demand.

		 * Use minimal max_active at alloc time to reduce resource

		 * usage.

		 */

		ret->current_active = 1;

		ret->thresh = thresh;

	}



	if (flags & WQ_HIGHPRI)

		ret->normal_wq = alloc_workqueue("%s-%s-high", flags,

						 ret->max_active,

						 "btrfs", name);

						 ret->current_active, "btrfs",

						 name);

	else

		ret->normal_wq = alloc_workqueue("%s-%s", flags,

						 ret->max_active, "btrfs",

						 ret->current_active, "btrfs",

						 name);

	if (!ret->normal_wq) {

		kfree(ret);
@@ -134,7 +145,7 @@ __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq); 


struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,

					      unsigned int flags,

					      int max_active,

					      int limit_active,

					      int thresh)

{

	struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
@@ -143,14 +154,14 @@ struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name, 
		return NULL;



	ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,

					      max_active, thresh);

					      limit_active, thresh);

	if (!ret->normal) {

		kfree(ret);

		return NULL;

	}



	if (flags & WQ_HIGHPRI) {

		ret->high = __btrfs_alloc_workqueue(name, flags, max_active,

		ret->high = __btrfs_alloc_workqueue(name, flags, limit_active,

						    thresh);

		if (!ret->high) {

			__btrfs_destroy_workqueue(ret->normal);
@@ -180,7 +191,7 @@ static inline void thresh_queue_hook(struct __btrfs_workqueue *wq) 
 */

static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)

{

	int new_max_active;

	int new_current_active;

	long pending;

	int need_change = 0;
@@ -197,7 +208,7 @@ static inline void thresh_exec_hook(struct __btrfs_workqueue *wq) 
	wq->count %= (wq->thresh / 4);

	if (!wq->count)

		goto  out;

	new_max_active = wq->current_max;

	new_current_active = wq->current_active;



	/*

	 * pending may be changed later, but it's OK since we really
@@ -205,19 +216,19 @@ static inline void thresh_exec_hook(struct __btrfs_workqueue *wq) 
	 */

	pending = atomic_read(&wq->pending);

	if (pending > wq->thresh)

		new_max_active++;

		new_current_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)  {

		new_current_active--;

	new_current_active = clamp_val(new_current_active, 1, wq->limit_active);

	if (new_current_active != wq->current_active)  {

		need_change = 1;

		wq->current_max = new_max_active;

		wq->current_active = new_current_active;

	}

out:

	spin_unlock(&wq->thres_lock);



	if (need_change) {

		workqueue_set_max_active(wq->normal_wq, wq->current_max);

		workqueue_set_max_active(wq->normal_wq, wq->current_active);

	}

}
@@ -351,13 +362,13 @@ void btrfs_destroy_workqueue(struct btrfs_workqueue *wq) 
	kfree(wq);

}



void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)

void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active)

{

	if (!wq)

		return;

	wq->normal->max_active = max;

	wq->normal->limit_active = limit_active;

	if (wq->high)

		wq->high->max_active = max;

		wq->high->limit_active = limit_active;

}



void btrfs_set_work_high_priority(struct btrfs_work *work)

fs/btrfs/async-thread.h

+1 −1
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ BTRFS_WORK_HELPER_PROTO(scrubparity_helper); 


struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,

					      unsigned int flags,

					      int max_active,

					      int limit_active,

					      int thresh);

void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t helper,

		     btrfs_func_t func,