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/alloc.c b/drivers/md/bcache/alloc.c
index 1b64e66..b9bd586 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -210,7 +210,7 @@
* multiple times when it can't do anything
*/
ca->invalidate_needs_gc = 1;
- bch_queue_gc(ca->set);
+ wake_up_gc(ca->set);
return;
}
@@ -235,7 +235,7 @@
if (++checked >= ca->sb.nbuckets) {
ca->invalidate_needs_gc = 1;
- bch_queue_gc(ca->set);
+ wake_up_gc(ca->set);
return;
}
}
@@ -260,7 +260,7 @@
if (++checked >= ca->sb.nbuckets / 2) {
ca->invalidate_needs_gc = 1;
- bch_queue_gc(ca->set);
+ wake_up_gc(ca->set);
return;
}
}
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index d352074..09410eb 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -773,7 +773,7 @@
struct gc_stat gc_stats;
size_t nbuckets;
- struct closure_with_waitlist gc;
+ struct task_struct *gc_thread;
/* Where in the btree gc currently is */
struct bkey gc_done;
@@ -786,11 +786,10 @@
/* Counts how many sectors bio_insert has added to the cache */
atomic_t sectors_to_gc;
- struct closure moving_gc;
- struct closure_waitlist moving_gc_wait;
+ wait_queue_head_t moving_gc_wait;
struct keybuf moving_gc_keys;
/* Number of moving GC bios in flight */
- atomic_t in_flight;
+ struct semaphore moving_in_flight;
struct btree *root;
@@ -1176,7 +1175,7 @@
void bch_prio_write(struct cache *);
void bch_write_bdev_super(struct cached_dev *, struct closure *);
-extern struct workqueue_struct *bcache_wq, *bch_gc_wq;
+extern struct workqueue_struct *bcache_wq;
extern const char * const bch_cache_modes[];
extern struct mutex bch_register_lock;
extern struct list_head bch_cache_sets;
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;
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index d691d95..fa9641a 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -388,12 +388,18 @@
int bch_btree_search_recurse(struct btree *, struct btree_op *);
-void bch_queue_gc(struct cache_set *);
+int bch_gc_thread_start(struct cache_set *);
size_t bch_btree_gc_finish(struct cache_set *);
-void bch_moving_gc(struct closure *);
+void bch_moving_gc(struct cache_set *);
int bch_btree_check(struct cache_set *, struct btree_op *);
uint8_t __bch_btree_mark_key(struct cache_set *, int, struct bkey *);
+static inline void wake_up_gc(struct cache_set *c)
+{
+ if (c->gc_thread)
+ wake_up_process(c->gc_thread);
+}
+
void bch_keybuf_init(struct keybuf *);
void bch_refill_keybuf(struct cache_set *, struct keybuf *, struct bkey *,
keybuf_pred_fn *);
diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 2c42377..6ba0504 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -57,8 +57,7 @@
bch_keybuf_del(&io->s.op.c->moving_gc_keys, io->w);
- atomic_dec_bug(&io->s.op.c->in_flight);
- closure_wake_up(&io->s.op.c->moving_gc_wait);
+ up(&io->s.op.c->moving_in_flight);
closure_return_with_destructor(cl, moving_io_destructor);
}
@@ -113,7 +112,7 @@
bch_data_insert(&s->op.cl);
}
- continue_at(cl, write_moving_finish, bch_gc_wq);
+ continue_at(cl, write_moving_finish, system_wq);
}
static void read_moving_submit(struct closure *cl)
@@ -124,15 +123,17 @@
bch_submit_bbio(bio, s->op.c, &io->w->key, 0);
- continue_at(cl, write_moving, bch_gc_wq);
+ continue_at(cl, write_moving, system_wq);
}
-static void read_moving(struct closure *cl)
+static void read_moving(struct cache_set *c)
{
- struct cache_set *c = container_of(cl, struct cache_set, moving_gc);
struct keybuf_key *w;
struct moving_io *io;
struct bio *bio;
+ struct closure cl;
+
+ closure_init_stack(&cl);
/* XXX: if we error, background writeback could stall indefinitely */
@@ -164,13 +165,8 @@
trace_bcache_gc_copy(&w->key);
- closure_call(&io->s.cl, read_moving_submit, NULL, &c->gc.cl);
-
- if (atomic_inc_return(&c->in_flight) >= 64) {
- closure_wait_event(&c->moving_gc_wait, cl,
- atomic_read(&c->in_flight) < 64);
- continue_at(cl, read_moving, bch_gc_wq);
- }
+ down(&c->moving_in_flight);
+ closure_call(&io->s.cl, read_moving_submit, NULL, &cl);
}
if (0) {
@@ -180,7 +176,7 @@
bch_keybuf_del(&c->moving_gc_keys, w);
}
- closure_return(cl);
+ closure_sync(&cl);
}
static bool bucket_cmp(struct bucket *l, struct bucket *r)
@@ -193,15 +189,14 @@
return GC_SECTORS_USED(heap_peek(&ca->heap));
}
-void bch_moving_gc(struct closure *cl)
+void bch_moving_gc(struct cache_set *c)
{
- struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
struct cache *ca;
struct bucket *b;
unsigned i;
if (!c->copy_gc_enabled)
- closure_return(cl);
+ return;
mutex_lock(&c->bucket_lock);
@@ -242,13 +237,11 @@
c->moving_gc_keys.last_scanned = ZERO_KEY;
- closure_init(&c->moving_gc, cl);
- read_moving(&c->moving_gc);
-
- closure_return(cl);
+ read_moving(c);
}
void bch_moving_init_cache_set(struct cache_set *c)
{
bch_keybuf_init(&c->moving_gc_keys);
+ sema_init(&c->moving_in_flight, 64);
}
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 26d18f4..f779eb4 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -520,7 +520,7 @@
if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
set_gc_sectors(op->c);
- bch_queue_gc(op->c);
+ wake_up_gc(op->c);
}
/*
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 84398a8..f89e229 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1342,6 +1342,9 @@
kobject_put(&c->internal);
kobject_del(&c->kobj);
+ if (c->gc_thread)
+ kthread_stop(c->gc_thread);
+
if (!IS_ERR_OR_NULL(c->root))
list_add(&c->root->list, &c->btree_cache);
@@ -1579,8 +1582,6 @@
bch_journal_replay(c, &journal, &op);
} else {
pr_notice("invalidating existing data");
- /* Don't want invalidate_buckets() to queue a gc yet */
- closure_lock(&c->gc, NULL);
for_each_cache(ca, c, i) {
unsigned j;
@@ -1606,12 +1607,12 @@
err = "cannot allocate new UUID bucket";
if (__uuid_write(c))
- goto err_unlock_gc;
+ goto err;
err = "cannot allocate new btree root";
c->root = bch_btree_node_alloc(c, 0);
if (IS_ERR_OR_NULL(c->root))
- goto err_unlock_gc;
+ goto err;
bkey_copy_key(&c->root->key, &MAX_KEY);
bch_btree_node_write(c->root, &op.cl);
@@ -1628,12 +1629,12 @@
bch_journal_next(&c->journal);
bch_journal_meta(c, &op.cl);
-
- /* Unlock */
- closure_set_stopped(&c->gc.cl);
- closure_put(&c->gc.cl);
}
+ err = "error starting gc thread";
+ if (bch_gc_thread_start(c))
+ goto err;
+
closure_sync(&op.cl);
c->sb.last_mount = get_seconds();
bcache_write_super(c);
@@ -1644,9 +1645,6 @@
flash_devs_run(c);
return;
-err_unlock_gc:
- closure_set_stopped(&c->gc.cl);
- closure_put(&c->gc.cl);
err:
closure_sync(&op.cl);
/* XXX: test this, it's broken */
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index b3a66f1..ab286b9 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -566,7 +566,7 @@
}
if (attr == &sysfs_trigger_gc)
- bch_queue_gc(c);
+ wake_up_gc(c);
if (attr == &sysfs_prune_cache) {
struct shrink_control sc;