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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: Alex Lyakas <alex.btrfs@zadarastorage.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Qu Wenruo 2015-08-20 09:30:39 +08:00 committed by Chris Mason
parent 943c6e9925
commit c6dd6ea557
2 changed files with 35 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
fs/btrfs/async-thread.c
View File

@ -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)

2
fs/btrfs/async-thread.h
View File

@ -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,