Commit 79826c35 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Allocation kthread fixes 



The alloc kthread should've been using try_to_freeze() - and also there
was the potential for the alloc kthread to get woken up after it had
shut down, which would have been bad.

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent 29ebf465

drivers/md/bcache/alloc.c

+8 −10
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ 
#include "bcache.h"

#include "btree.h"



#include <linux/freezer.h>

#include <linux/kthread.h>

#include <linux/random.h>

#include <trace/events/bcache.h>
@@ -363,11 +364,10 @@ do { \ 
			break;						\

									\

		mutex_unlock(&(ca)->set->bucket_lock);			\

		if (test_bit(CACHE_SET_STOPPING_2, &ca->set->flags)) {	\

			closure_put(&ca->set->cl);			\

		if (kthread_should_stop())				\

			return 0;					\

		}							\

									\

		try_to_freeze();					\

		schedule();						\

		mutex_lock(&(ca)->set->bucket_lock);			\

	}								\
@@ -547,14 +547,12 @@ int bch_bucket_alloc_set(struct cache_set *c, unsigned watermark, 


int bch_cache_allocator_start(struct cache *ca)

{

	ca->alloc_thread = kthread_create(bch_allocator_thread,

	struct task_struct *k = kthread_run(bch_allocator_thread,

					    ca, "bcache_allocator");

	if (IS_ERR(ca->alloc_thread))

		return PTR_ERR(ca->alloc_thread);



	closure_get(&ca->set->cl);

	wake_up_process(ca->alloc_thread);

	if (IS_ERR(k))

		return PTR_ERR(k);



	ca->alloc_thread = k;

	return 0;

}

drivers/md/bcache/bcache.h

+0 −4
Original line number Diff line number Diff line
@@ -664,13 +664,9 @@ struct gc_stat { 
 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set;

 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e.

 * flushing dirty data).

 *

 * CACHE_SET_STOPPING_2 gets set at the last phase, when it's time to shut down

 * the allocation thread.

 */

#define CACHE_SET_UNREGISTERING		0

#define	CACHE_SET_STOPPING		1

#define	CACHE_SET_STOPPING_2		2



struct cache_set {

	struct closure		cl;

drivers/md/bcache/super.c

+7 −4
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/buffer_head.h>

#include <linux/debugfs.h>

#include <linux/genhd.h>

#include <linux/kthread.h>

#include <linux/module.h>

#include <linux/random.h>

#include <linux/reboot.h>
@@ -1329,11 +1330,9 @@ static void cache_set_free(struct closure *cl) 
static void cache_set_flush(struct closure *cl)

{

	struct cache_set *c = container_of(cl, struct cache_set, caching);

	struct cache *ca;

	struct btree *b;



	/* Shut down allocator threads */

	set_bit(CACHE_SET_STOPPING_2, &c->flags);

	wake_up_allocators(c);

	unsigned i;



	bch_cache_accounting_destroy(&c->accounting);
@@ -1348,6 +1347,10 @@ static void cache_set_flush(struct closure *cl) 
		if (btree_node_dirty(b))

			bch_btree_node_write(b, NULL);



	for_each_cache(ca, c, i)

		if (ca->alloc_thread)

			kthread_stop(ca->alloc_thread);



	closure_return(cl);

}