bcache: Convert gc to a kthread
We needed a dedicated rescuer workqueue for gc anyways... and gc was
conceptually a dedicated thread, just one that wasn't running all the
time. Switch it to a dedicated thread to make the code a bit more
straightforward.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 935d90d..17bfd87 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -28,7 +28,9 @@
#include <linux/slab.h>
#include <linux/bitops.h>
+#include <linux/freezer.h>
#include <linux/hash.h>
+#include <linux/kthread.h>
#include <linux/prefetch.h>
#include <linux/random.h>
#include <linux/rcupdate.h>
@@ -105,7 +107,6 @@
#define PTR_HASH(c, k) \
(((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0))
-struct workqueue_struct *bch_gc_wq;
static struct workqueue_struct *btree_io_wq;
void bch_btree_op_init_stack(struct btree_op *op)
@@ -732,12 +733,9 @@
{
unsigned i;
- /* XXX: doesn't check for errors */
-
- closure_init_unlocked(&c->gc);
-
for (i = 0; i < mca_reserve(c); i++)
- mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
+ if (!mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL))
+ return -ENOMEM;
list_splice_init(&c->btree_cache,
&c->btree_cache_freeable);
@@ -1456,9 +1454,8 @@
return available;
}
-static void bch_btree_gc(struct closure *cl)
+static void bch_btree_gc(struct cache_set *c)
{
- struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
int ret;
unsigned long available;
struct gc_stat stats;
@@ -1483,7 +1480,7 @@
if (ret) {
pr_warn("gc failed!");
- continue_at(cl, bch_btree_gc, bch_gc_wq);
+ return;
}
/* Possibly wait for new UUIDs or whatever to hit disk */
@@ -1505,12 +1502,35 @@
trace_bcache_gc_end(c);
- continue_at(cl, bch_moving_gc, bch_gc_wq);
+ bch_moving_gc(c);
}
-void bch_queue_gc(struct cache_set *c)
+static int bch_gc_thread(void *arg)
{
- closure_trylock_call(&c->gc.cl, bch_btree_gc, bch_gc_wq, &c->cl);
+ struct cache_set *c = arg;
+
+ while (1) {
+ bch_btree_gc(c);
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (kthread_should_stop())
+ break;
+
+ try_to_freeze();
+ schedule();
+ }
+
+ return 0;
+}
+
+int bch_gc_thread_start(struct cache_set *c)
+{
+ c->gc_thread = kthread_create(bch_gc_thread, c, "bcache_gc");
+ if (IS_ERR(c->gc_thread))
+ return PTR_ERR(c->gc_thread);
+
+ set_task_state(c->gc_thread, TASK_INTERRUPTIBLE);
+ return 0;
}
/* Initial partial gc */
@@ -2480,14 +2500,12 @@
{
if (btree_io_wq)
destroy_workqueue(btree_io_wq);
- if (bch_gc_wq)
- destroy_workqueue(bch_gc_wq);
}
int __init bch_btree_init(void)
{
- if (!(bch_gc_wq = create_singlethread_workqueue("bch_btree_gc")) ||
- !(btree_io_wq = create_singlethread_workqueue("bch_btree_io")))
+ btree_io_wq = create_singlethread_workqueue("bch_btree_io");
+ if (!btree_io_wq)
return -ENOMEM;
return 0;