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writeback: remove struct bdi_writeback_congested

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We never set any congested bits in the group writeback instances of it.
And for the simpler bdi-wide case a simple scalar field is all that
that is needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2020-07-01 11:06:21 +02:00
committed by Jens Axboe
parent 492d76b215
commit 8c911f3d4c
6 changed files with 14 additions and 205 deletions
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149
mm/backing-dev.c
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@@ -281,7 +281,7 @@ void wb_wakeup_delayed(struct bdi_writeback *wb)
#define INIT_BW (100 << (20 - PAGE_SHIFT))
static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
int blkcg_id, gfp_t gfp)
gfp_t gfp)
{
int i, err;
@@ -308,15 +308,9 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
wb->dirty_sleep = jiffies;
wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
if (!wb->congested) {
err = -ENOMEM;
goto out_put_bdi;
}
err = fprop_local_init_percpu(&wb->completions, gfp);
if (err)
goto out_put_cong;
goto out_put_bdi;
for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
err = percpu_counter_init(&wb->stat[i], 0, gfp);
@@ -330,8 +324,6 @@ out_destroy_stat:
while (i--)
percpu_counter_destroy(&wb->stat[i]);
fprop_local_destroy_percpu(&wb->completions);
out_put_cong:
wb_congested_put(wb->congested);
out_put_bdi:
if (wb != &bdi->wb)
bdi_put(bdi);
@@ -374,7 +366,6 @@ static void wb_exit(struct bdi_writeback *wb)
percpu_counter_destroy(&wb->stat[i]);
fprop_local_destroy_percpu(&wb->completions);
wb_congested_put(wb->congested);
if (wb != &wb->bdi->wb)
bdi_put(wb->bdi);
}
@@ -384,99 +375,12 @@ static void wb_exit(struct bdi_writeback *wb)
#include <linux/memcontrol.h>
/*
* cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
* blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
* protected.
* cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, and memcg->cgwb_list.
* bdi->cgwb_tree is also RCU protected.
*/
static DEFINE_SPINLOCK(cgwb_lock);
static struct workqueue_struct *cgwb_release_wq;
/**
* wb_congested_get_create - get or create a wb_congested
* @bdi: associated bdi
* @blkcg_id: ID of the associated blkcg
* @gfp: allocation mask
*
* Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
* The returned wb_congested has its reference count incremented. Returns
* NULL on failure.
*/
struct bdi_writeback_congested *
wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
{
struct bdi_writeback_congested *new_congested = NULL, *congested;
struct rb_node **node, *parent;
unsigned long flags;
retry:
spin_lock_irqsave(&cgwb_lock, flags);
node = &bdi->cgwb_congested_tree.rb_node;
parent = NULL;
while (*node != NULL) {
parent = *node;
congested = rb_entry(parent, struct bdi_writeback_congested,
rb_node);
if (congested->blkcg_id < blkcg_id)
node = &parent->rb_left;
else if (congested->blkcg_id > blkcg_id)
node = &parent->rb_right;
else
goto found;
}
if (new_congested) {
/* !found and storage for new one already allocated, insert */
congested = new_congested;
rb_link_node(&congested->rb_node, parent, node);
rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
spin_unlock_irqrestore(&cgwb_lock, flags);
return congested;
}
spin_unlock_irqrestore(&cgwb_lock, flags);
/* allocate storage for new one and retry */
new_congested = kzalloc(sizeof(*new_congested), gfp);
if (!new_congested)
return NULL;
refcount_set(&new_congested->refcnt, 1);
new_congested->__bdi = bdi;
new_congested->blkcg_id = blkcg_id;
goto retry;
found:
refcount_inc(&congested->refcnt);
spin_unlock_irqrestore(&cgwb_lock, flags);
kfree(new_congested);
return congested;
}
/**
* wb_congested_put - put a wb_congested
* @congested: wb_congested to put
*
* Put @congested and destroy it if the refcnt reaches zero.
*/
void wb_congested_put(struct bdi_writeback_congested *congested)
{
unsigned long flags;
if (!refcount_dec_and_lock_irqsave(&congested->refcnt, &cgwb_lock, &flags))
return;
/* bdi might already have been destroyed leaving @congested unlinked */
if (congested->__bdi) {
rb_erase(&congested->rb_node,
&congested->__bdi->cgwb_congested_tree);
congested->__bdi = NULL;
}
spin_unlock_irqrestore(&cgwb_lock, flags);
kfree(congested);
}
static void cgwb_release_workfn(struct work_struct *work)
{
struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
@@ -558,7 +462,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
goto out_put;
}
ret = wb_init(wb, bdi, blkcg_css->id, gfp);
ret = wb_init(wb, bdi, gfp);
if (ret)
goto err_free;
@@ -696,11 +600,10 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
int ret;
INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
bdi->cgwb_congested_tree = RB_ROOT;
mutex_init(&bdi->cgwb_release_mutex);
init_rwsem(&bdi->wb_switch_rwsem);
ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
if (!ret) {
bdi->wb.memcg_css = &root_mem_cgroup->css;
bdi->wb.blkcg_css = blkcg_root_css;
@@ -769,21 +672,6 @@ void wb_blkcg_offline(struct blkcg *blkcg)
spin_unlock_irq(&cgwb_lock);
}
static void cgwb_bdi_exit(struct backing_dev_info *bdi)
{
struct rb_node *rbn;
spin_lock_irq(&cgwb_lock);
while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
struct bdi_writeback_congested *congested =
rb_entry(rbn, struct bdi_writeback_congested, rb_node);
rb_erase(rbn, &bdi->cgwb_congested_tree);
congested->__bdi = NULL; /* mark @congested unlinked */
}
spin_unlock_irq(&cgwb_lock);
}
static void cgwb_bdi_register(struct backing_dev_info *bdi)
{
spin_lock_irq(&cgwb_lock);
@@ -810,29 +698,11 @@ subsys_initcall(cgwb_init);
static int cgwb_bdi_init(struct backing_dev_info *bdi)
{
int err;
bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
if (!bdi->wb_congested)
return -ENOMEM;
refcount_set(&bdi->wb_congested->refcnt, 1);
err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
if (err) {
wb_congested_put(bdi->wb_congested);
return err;
}
return 0;
return wb_init(&bdi->wb, bdi, GFP_KERNEL);
}
static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
static void cgwb_bdi_exit(struct backing_dev_info *bdi)
{
wb_congested_put(bdi->wb_congested);
}
static void cgwb_bdi_register(struct backing_dev_info *bdi)
{
list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
@@ -1023,7 +893,6 @@ static void release_bdi(struct kref *ref)
bdi_unregister(bdi);
WARN_ON_ONCE(bdi->dev);
wb_exit(&bdi->wb);
cgwb_bdi_exit(bdi);
kfree(bdi);
}
@@ -1053,7 +922,7 @@ void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
enum wb_congested_state bit;
bit = sync ? WB_sync_congested : WB_async_congested;
if (test_and_clear_bit(bit, &bdi->wb.congested->state))
if (test_and_clear_bit(bit, &bdi->wb.congested))
atomic_dec(&nr_wb_congested[sync]);
smp_mb__after_atomic();
if (waitqueue_active(wqh))
@@ -1066,7 +935,7 @@ void set_bdi_congested(struct backing_dev_info *bdi, int sync)
enum wb_congested_state bit;
bit = sync ? WB_sync_congested : WB_async_congested;
if (!test_and_set_bit(bit, &bdi->wb.congested->state))
if (!test_and_set_bit(bit, &bdi->wb.congested))
atomic_inc(&nr_wb_congested[sync]);
}
EXPORT_SYMBOL(set_bdi_congested);