From cb7a583e6a6ace661a5890803e115d2292a293df Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kmo@daterainc.com>
Date: Mon, 16 Dec 2013 15:27:25 -0800
Subject: bcache: kill closure locking usage

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index dbdbca5..9d062bc 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -309,7 +309,8 @@ struct cached_dev {
 	struct cache_sb		sb;
 	struct bio		sb_bio;
 	struct bio_vec		sb_bv[1];
-	struct closure_with_waitlist sb_write;
+	struct closure		sb_write;
+	struct semaphore	sb_write_mutex;
 
 	/* Refcount on the cache set. Always nonzero when we're caching. */
 	atomic_t		count;
@@ -514,7 +515,8 @@ struct cache_set {
 	uint64_t		cached_dev_sectors;
 	struct closure		caching;
 
-	struct closure_with_waitlist sb_write;
+	struct closure		sb_write;
+	struct semaphore	sb_write_mutex;
 
 	mempool_t		*search;
 	mempool_t		*bio_meta;
@@ -635,7 +637,8 @@ struct cache_set {
 	unsigned		nr_uuids;
 	struct uuid_entry	*uuids;
 	BKEY_PADDED(uuid_bucket);
-	struct closure_with_waitlist uuid_write;
+	struct closure		uuid_write;
+	struct semaphore	uuid_write_mutex;
 
 	/*
 	 * A btree node on disk could have too many bsets for an iterator to fit
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index aaa87b3..101231f 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -340,9 +340,16 @@ static void btree_complete_write(struct btree *b, struct btree_write *w)
 	w->journal	= NULL;
 }
 
+static void btree_node_write_unlock(struct closure *cl)
+{
+	struct btree *b = container_of(cl, struct btree, io);
+
+	up(&b->io_mutex);
+}
+
 static void __btree_node_write_done(struct closure *cl)
 {
-	struct btree *b = container_of(cl, struct btree, io.cl);
+	struct btree *b = container_of(cl, struct btree, io);
 	struct btree_write *w = btree_prev_write(b);
 
 	bch_bbio_free(b->bio, b->c);
@@ -353,12 +360,12 @@ static void __btree_node_write_done(struct closure *cl)
 		queue_delayed_work(btree_io_wq, &b->work,
 				   msecs_to_jiffies(30000));
 
-	closure_return(cl);
+	closure_return_with_destructor(cl, btree_node_write_unlock);
 }
 
 static void btree_node_write_done(struct closure *cl)
 {
-	struct btree *b = container_of(cl, struct btree, io.cl);
+	struct btree *b = container_of(cl, struct btree, io);
 	struct bio_vec *bv;
 	int n;
 
@@ -371,7 +378,7 @@ static void btree_node_write_done(struct closure *cl)
 static void btree_node_write_endio(struct bio *bio, int error)
 {
 	struct closure *cl = bio->bi_private;
-	struct btree *b = container_of(cl, struct btree, io.cl);
+	struct btree *b = container_of(cl, struct btree, io);
 
 	if (error)
 		set_btree_node_io_error(b);
@@ -382,7 +389,7 @@ static void btree_node_write_endio(struct bio *bio, int error)
 
 static void do_btree_node_write(struct btree *b)
 {
-	struct closure *cl = &b->io.cl;
+	struct closure *cl = &b->io;
 	struct bset *i = b->sets[b->nsets].data;
 	BKEY_PADDED(key) k;
 
@@ -435,7 +442,7 @@ static void do_btree_node_write(struct btree *b)
 		bch_submit_bbio(b->bio, b->c, &k.key, 0);
 
 		closure_sync(cl);
-		__btree_node_write_done(cl);
+		continue_at_nobarrier(cl, __btree_node_write_done, NULL);
 	}
 }
 
@@ -454,7 +461,8 @@ void bch_btree_node_write(struct btree *b, struct closure *parent)
 	cancel_delayed_work(&b->work);
 
 	/* If caller isn't waiting for write, parent refcount is cache set */
-	closure_lock(&b->io, parent ?: &b->c->cl);
+	down(&b->io_mutex);
+	closure_init(&b->io, parent ?: &b->c->cl);
 
 	clear_bit(BTREE_NODE_dirty,	 &b->flags);
 	change_bit(BTREE_NODE_write_idx, &b->flags);
@@ -554,7 +562,8 @@ static void mca_reinit(struct btree *b)
 static void mca_data_free(struct btree *b)
 {
 	struct bset_tree *t = b->sets;
-	BUG_ON(!closure_is_unlocked(&b->io.cl));
+
+	BUG_ON(b->io_mutex.count != 1);
 
 	if (bset_prev_bytes(b) < PAGE_SIZE)
 		kfree(t->prev);
@@ -635,7 +644,7 @@ static struct btree *mca_bucket_alloc(struct cache_set *c,
 	INIT_LIST_HEAD(&b->list);
 	INIT_DELAYED_WORK(&b->work, btree_node_write_work);
 	b->c = c;
-	closure_init_unlocked(&b->io);
+	sema_init(&b->io_mutex, 1);
 
 	mca_data_alloc(b, k, gfp);
 	return b;
@@ -653,22 +662,29 @@ static int mca_reap(struct btree *b, unsigned min_order, bool flush)
 
 	BUG_ON(btree_node_dirty(b) && !b->sets[0].data);
 
-	if (b->page_order < min_order ||
-	    (!flush &&
-	     (btree_node_dirty(b) ||
-	      atomic_read(&b->io.cl.remaining) != -1))) {
-		rw_unlock(true, b);
-		return -ENOMEM;
+	if (b->page_order < min_order)
+		goto out_unlock;
+
+	if (!flush) {
+		if (btree_node_dirty(b))
+			goto out_unlock;
+
+		if (down_trylock(&b->io_mutex))
+			goto out_unlock;
+		up(&b->io_mutex);
 	}
 
 	if (btree_node_dirty(b))
 		bch_btree_node_write_sync(b);
 
 	/* wait for any in flight btree write */
-	closure_wait_event(&b->io.wait, &cl,
-			   atomic_read(&b->io.cl.remaining) == -1);
+	down(&b->io_mutex);
+	up(&b->io_mutex);
 
 	return 0;
+out_unlock:
+	rw_unlock(true, b);
+	return -ENOMEM;
 }
 
 static unsigned long bch_mca_scan(struct shrinker *shrink,
@@ -918,7 +934,7 @@ static struct btree *mca_alloc(struct cache_set *c, struct bkey *k, int level)
 	if (!b->sets->data)
 		goto err;
 out:
-	BUG_ON(!closure_is_unlocked(&b->io.cl));
+	BUG_ON(b->io_mutex.count != 1);
 
 	bkey_copy(&b->key, k);
 	list_move(&b->list, &c->btree_cache);
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index 767e755..d68af74 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -143,7 +143,8 @@ struct btree {
 	struct bset_tree	sets[MAX_BSETS];
 
 	/* For outstanding btree writes, used as a lock - protects write_idx */
-	struct closure_with_waitlist	io;
+	struct closure		io;
+	struct semaphore	io_mutex;
 
 	struct list_head	list;
 	struct delayed_work	work;
diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index 03cb4d1..fab3767 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c
@@ -127,9 +127,7 @@ void bch_btree_verify(struct btree *b, struct bset *new)
 	if (!b->c->verify)
 		return;
 
-	closure_wait_event(&b->io.wait, &cl,
-			   atomic_read(&b->io.cl.remaining) == -1);
-
+	down(&b->io_mutex);
 	mutex_lock(&b->c->verify_lock);
 
 	bkey_copy(&v->key, &b->key);
@@ -137,8 +135,6 @@ void bch_btree_verify(struct btree *b, struct bset *new)
 	v->level = b->level;
 
 	bch_btree_node_read(v);
-	closure_wait_event(&v->io.wait, &cl,
-			   atomic_read(&b->io.cl.remaining) == -1);
 
 	if (new->keys != v->sets[0].data->keys ||
 	    memcmp(new->start,
@@ -167,6 +163,7 @@ void bch_btree_verify(struct btree *b, struct bset *new)
 	}
 
 	mutex_unlock(&b->c->verify_lock);
+	up(&b->io_mutex);
 }
 
 void bch_data_verify(struct cached_dev *dc, struct bio *bio)
diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index ad68728..9d32d57 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -564,6 +564,14 @@ static void journal_write_done(struct closure *cl)
 	continue_at_nobarrier(cl, journal_write, system_wq);
 }
 
+static void journal_write_unlock(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, journal.io);
+
+	c->journal.io_in_flight = 0;
+	spin_unlock(&c->journal.lock);
+}
+
 static void journal_write_unlocked(struct closure *cl)
 	__releases(c->journal.lock)
 {
@@ -578,15 +586,7 @@ static void journal_write_unlocked(struct closure *cl)
 	bio_list_init(&list);
 
 	if (!w->need_write) {
-		/*
-		 * XXX: have to unlock closure before we unlock journal lock,
-		 * else we race with bch_journal(). But this way we race
-		 * against cache set unregister. Doh.
-		 */
-		set_closure_fn(cl, NULL, NULL);
-		closure_sub(cl, CLOSURE_RUNNING + 1);
-		spin_unlock(&c->journal.lock);
-		return;
+		closure_return_with_destructor(cl, journal_write_unlock);
 	} else if (journal_full(&c->journal)) {
 		journal_reclaim(c);
 		spin_unlock(&c->journal.lock);
@@ -662,10 +662,12 @@ static void journal_try_write(struct cache_set *c)
 
 	w->need_write = true;
 
-	if (closure_trylock(cl, &c->cl))
-		journal_write_unlocked(cl);
-	else
+	if (!c->journal.io_in_flight) {
+		c->journal.io_in_flight = 1;
+		closure_call(cl, journal_write_unlocked, NULL, &c->cl);
+	} else {
 		spin_unlock(&c->journal.lock);
+	}
 }
 
 static struct journal_write *journal_wait_for_write(struct cache_set *c,
@@ -793,7 +795,6 @@ int bch_journal_alloc(struct cache_set *c)
 {
 	struct journal *j = &c->journal;
 
-	closure_init_unlocked(&j->io);
 	spin_lock_init(&j->lock);
 	INIT_DELAYED_WORK(&j->work, journal_write_work);
 
diff --git a/drivers/md/bcache/journal.h b/drivers/md/bcache/journal.h
index a6472fd..9180c44 100644
--- a/drivers/md/bcache/journal.h
+++ b/drivers/md/bcache/journal.h
@@ -104,6 +104,7 @@ struct journal {
 	/* used when waiting because the journal was full */
 	struct closure_waitlist	wait;
 	struct closure		io;
+	int			io_in_flight;
 	struct delayed_work	work;
 
 	/* Number of blocks free in the bucket(s) we're currently writing to */
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 93d593f..b057676 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -225,7 +225,7 @@ static void write_bdev_super_endio(struct bio *bio, int error)
 	struct cached_dev *dc = bio->bi_private;
 	/* XXX: error checking */
 
-	closure_put(&dc->sb_write.cl);
+	closure_put(&dc->sb_write);
 }
 
 static void __write_super(struct cache_sb *sb, struct bio *bio)
@@ -263,12 +263,20 @@ static void __write_super(struct cache_sb *sb, struct bio *bio)
 	submit_bio(REQ_WRITE, bio);
 }
 
+static void bch_write_bdev_super_unlock(struct closure *cl)
+{
+	struct cached_dev *dc = container_of(cl, struct cached_dev, sb_write);
+
+	up(&dc->sb_write_mutex);
+}
+
 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent)
 {
-	struct closure *cl = &dc->sb_write.cl;
+	struct closure *cl = &dc->sb_write;
 	struct bio *bio = &dc->sb_bio;
 
-	closure_lock(&dc->sb_write, parent);
+	down(&dc->sb_write_mutex);
+	closure_init(cl, parent);
 
 	bio_reset(bio);
 	bio->bi_bdev	= dc->bdev;
@@ -278,7 +286,7 @@ void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent)
 	closure_get(cl);
 	__write_super(&dc->sb, bio);
 
-	closure_return(cl);
+	closure_return_with_destructor(cl, bch_write_bdev_super_unlock);
 }
 
 static void write_super_endio(struct bio *bio, int error)
@@ -286,16 +294,24 @@ static void write_super_endio(struct bio *bio, int error)
 	struct cache *ca = bio->bi_private;
 
 	bch_count_io_errors(ca, error, "writing superblock");
-	closure_put(&ca->set->sb_write.cl);
+	closure_put(&ca->set->sb_write);
+}
+
+static void bcache_write_super_unlock(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, sb_write);
+
+	up(&c->sb_write_mutex);
 }
 
 void bcache_write_super(struct cache_set *c)
 {
-	struct closure *cl = &c->sb_write.cl;
+	struct closure *cl = &c->sb_write;
 	struct cache *ca;
 	unsigned i;
 
-	closure_lock(&c->sb_write, &c->cl);
+	down(&c->sb_write_mutex);
+	closure_init(cl, &c->cl);
 
 	c->sb.seq++;
 
@@ -317,7 +333,7 @@ void bcache_write_super(struct cache_set *c)
 		__write_super(&ca->sb, bio);
 	}
 
-	closure_return(cl);
+	closure_return_with_destructor(cl, bcache_write_super_unlock);
 }
 
 /* UUID io */
@@ -325,23 +341,31 @@ void bcache_write_super(struct cache_set *c)
 static void uuid_endio(struct bio *bio, int error)
 {
 	struct closure *cl = bio->bi_private;
-	struct cache_set *c = container_of(cl, struct cache_set, uuid_write.cl);
+	struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
 
 	cache_set_err_on(error, c, "accessing uuids");
 	bch_bbio_free(bio, c);
 	closure_put(cl);
 }
 
+static void uuid_io_unlock(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
+
+	up(&c->uuid_write_mutex);
+}
+
 static void uuid_io(struct cache_set *c, unsigned long rw,
 		    struct bkey *k, struct closure *parent)
 {
-	struct closure *cl = &c->uuid_write.cl;
+	struct closure *cl = &c->uuid_write;
 	struct uuid_entry *u;
 	unsigned i;
 	char buf[80];
 
 	BUG_ON(!parent);
-	closure_lock(&c->uuid_write, parent);
+	down(&c->uuid_write_mutex);
+	closure_init(cl, parent);
 
 	for (i = 0; i < KEY_PTRS(k); i++) {
 		struct bio *bio = bch_bbio_alloc(c);
@@ -368,7 +392,7 @@ static void uuid_io(struct cache_set *c, unsigned long rw,
 				 u - c->uuids, u->uuid, u->label,
 				 u->first_reg, u->last_reg, u->invalidated);
 
-	closure_return(cl);
+	closure_return_with_destructor(cl, uuid_io_unlock);
 }
 
 static char *uuid_read(struct cache_set *c, struct jset *j, struct closure *cl)
@@ -1098,7 +1122,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned block_size)
 	set_closure_fn(&dc->disk.cl, cached_dev_flush, system_wq);
 	kobject_init(&dc->disk.kobj, &bch_cached_dev_ktype);
 	INIT_WORK(&dc->detach, cached_dev_detach_finish);
-	closure_init_unlocked(&dc->sb_write);
+	sema_init(&dc->sb_write_mutex, 1);
 	INIT_LIST_HEAD(&dc->io_lru);
 	spin_lock_init(&dc->io_lock);
 	bch_cache_accounting_init(&dc->accounting, &dc->disk.cl);
@@ -1454,11 +1478,11 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 
 	c->sort_crit_factor = int_sqrt(c->btree_pages);
 
-	closure_init_unlocked(&c->sb_write);
+	sema_init(&c->sb_write_mutex, 1);
 	mutex_init(&c->bucket_lock);
 	init_waitqueue_head(&c->try_wait);
 	init_waitqueue_head(&c->bucket_wait);
-	closure_init_unlocked(&c->uuid_write);
+	sema_init(&c->uuid_write_mutex, 1);
 	mutex_init(&c->sort_lock);
 
 	spin_lock_init(&c->sort_time.lock);
-- 
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