bcache: kill c->cache_slots_used

it wasn't actually needed, but it wasn't being set correctly and causing
assertions to fail

4 files changed, 12 insertions, 21 deletions

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 6903ab40ac6f..fca21a796c17 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -525,7 +525,6 @@ struct cache_set {
 	struct work_struct	read_only_work;
 
 	struct cache __rcu	*cache[MAX_CACHES_PER_SET];
-	unsigned long	cache_slots_used[BITS_TO_LONGS(MAX_CACHES_PER_SET)];
 
 	struct mutex		mi_lock;
 	struct cache_member_rcu __rcu *members;
diff --git a/drivers/md/bcache/btree_gc.c b/drivers/md/bcache/btree_gc.c
index a7fdec3e65a5..5dfa8e766717 100644
--- a/drivers/md/bcache/btree_gc.c
+++ b/drivers/md/bcache/btree_gc.c
@@ -99,10 +99,6 @@ u8 bch_btree_key_recalc_oldest_gen(struct cache_set *c, struct bkey_s_c k)
 
 		rcu_read_lock();
 
-		extent_for_each_ptr(e, ptr)
-			if (ptr->dev < MAX_CACHES_PER_SET)
-				__set_bit(ptr->dev, c->cache_slots_used);
-
 		extent_for_each_online_device(c, e, ptr, ca) {
 			struct bucket *g = PTR_BUCKET(ca, ptr);
 
@@ -349,8 +345,6 @@ void bch_gc(struct cache_set *c)
 	 *    uses, GC could skip past them
 	 */
 
-	memset(c->cache_slots_used, 0, sizeof(c->cache_slots_used));
-
 	if (test_bit(CACHE_SET_GC_FAILURE, &c->flags))
 		return;
 
diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c
index ee8202b47a87..c6b0a709f0cb 100644
--- a/drivers/md/bcache/extents.c
+++ b/drivers/md/bcache/extents.c
@@ -1521,15 +1521,10 @@ static void bch_extent_debugcheck_extent(struct cache_set *c, struct btree *b,
 		if (ptr->dev >= mi->nr_in_set)
 			goto bad_device;
 
-		do {
-			seq = read_seqcount_begin(&c->gc_pos_lock);
-			bad = !test_bit(ptr->dev, c->cache_slots_used) &&
-				c->gc_pos.phase == GC_PHASE_DONE;
-		} while (read_seqcount_retry(&c->gc_pos_lock, seq));
-
-		if (bad)
-			goto bad_device;
-
+		/*
+		 * If journal replay hasn't finished, we might be seeing keys
+		 * that will be overwritten by the time journal replay is done:
+		 */
 		if (!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags))
 			continue;
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2278eb5b36f6..e46bab05831d 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1823,6 +1823,11 @@ static void bch_cache_remove_work(struct work_struct *work)
 	synchronize_rcu();
 
 	lockdep_assert_held(&bch_register_lock);
+
+	/*
+	 * Free this device's slot in the cache_member array - all pointers to
+	 * this device must be gone:
+	 */
 	memset(&c->disk_mi[dev].uuid, 0, sizeof(c->disk_mi[dev].uuid));
 
 	bcache_write_super(c);
@@ -2118,10 +2123,9 @@ int bch_cache_set_add_cache(struct cache_set *c, const char *path)
 		goto no_slot;
 
 	for (nr_this_dev = 0; nr_this_dev < MAX_CACHES_PER_SET; nr_this_dev++)
-		if (!test_bit(nr_this_dev, c->cache_slots_used) &&
-		    (nr_this_dev >= c->sb.nr_in_set ||
-		     bch_is_zero(c->disk_mi[nr_this_dev].uuid.b,
-				 sizeof(uuid_le))))
+		if (nr_this_dev >= c->sb.nr_in_set ||
+		    bch_is_zero(c->disk_mi[nr_this_dev].uuid.b,
+				 sizeof(uuid_le)))
 			goto have_slot;
 no_slot:
 	up_read(&c->gc_lock);
@@ -2132,7 +2136,6 @@ no_slot:
 
 have_slot:
 	nr_in_set = max_t(unsigned, nr_this_dev + 1, c->sb.nr_in_set);
-	set_bit(nr_this_dev, c->cache_slots_used);
 	up_read(&c->gc_lock);
 
 	u64s = nr_in_set * (sizeof(struct cache_member) / sizeof(u64));