bcache: Add a real GC_MARK_RECLAIMABLE

This means the garbage collection code can better check for data and metadata
pointers to the same buckets.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

drivers/md/bcache/alloc.c

@@ -155,7 +155,8 @@ bool bch_bucket_add_unused(struct cache *ca, struct bucket *b)
 
 static bool can_invalidate_bucket(struct cache *ca, struct bucket *b)
 {
-	return GC_MARK(b) == GC_MARK_RECLAIMABLE &&
+	return (!GC_MARK(b) ||
+		GC_MARK(b) == GC_MARK_RECLAIMABLE) &&
 		!atomic_read(&b->pin) &&
 		can_inc_bucket_gen(b);
 }
@@ -475,7 +476,7 @@ void bch_bucket_free(struct cache_set *c, struct bkey *k)
 	for (i = 0; i < KEY_PTRS(k); i++) {
 		struct bucket *b = PTR_BUCKET(c, k, i);
 
-		SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
+		SET_GC_MARK(b, 0);
 		SET_GC_SECTORS_USED(b, 0);
 		bch_bucket_add_unused(PTR_CACHE(c, k, i), b);
 	}

drivers/md/bcache/bcache.h

@@ -207,9 +207,9 @@ struct bucket {
  */
 
 BITMASK(GC_MARK,	 struct bucket, gc_mark, 0, 2);
-#define GC_MARK_RECLAIMABLE	0
-#define GC_MARK_DIRTY		1
-#define GC_MARK_METADATA	2
+#define GC_MARK_RECLAIMABLE	1
+#define GC_MARK_DIRTY		2
+#define GC_MARK_METADATA	3
 #define GC_SECTORS_USED_SIZE	13
 #define MAX_GC_SECTORS_USED	(~(~0ULL << GC_SECTORS_USED_SIZE))
 BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE);

drivers/md/bcache/btree.c

@@ -1160,6 +1160,8 @@ static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
 			SET_GC_MARK(g, GC_MARK_METADATA);
 		else if (KEY_DIRTY(k))
 			SET_GC_MARK(g, GC_MARK_DIRTY);
+		else if (!GC_MARK(g))
+			SET_GC_MARK(g, GC_MARK_RECLAIMABLE);
 
 		/* guard against overflow */
 		SET_GC_SECTORS_USED(g, min_t(unsigned,
@@ -1559,7 +1561,7 @@ static void btree_gc_start(struct cache_set *c)
 		for_each_bucket(b, ca) {
 			b->gc_gen = b->gen;
 			if (!atomic_read(&b->pin)) {
-				SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
+				SET_GC_MARK(b, 0);
 				SET_GC_SECTORS_USED(b, 0);
 			}
 		}
@@ -1622,12 +1624,16 @@ size_t bch_btree_gc_finish(struct cache_set *c)
 			b->last_gc	= b->gc_gen;
 			c->need_gc	= max(c->need_gc, bucket_gc_gen(b));
 
-			if (!atomic_read(&b->pin) &&
-			    GC_MARK(b) == GC_MARK_RECLAIMABLE) {
+			if (atomic_read(&b->pin))
+				continue;
+
+			BUG_ON(!GC_MARK(b) && GC_SECTORS_USED(b));
+
+			if (!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE)
 				available++;
-				if (!GC_SECTORS_USED(b))
-					bch_bucket_add_unused(ca, b);
-			}
+
+			if (!GC_MARK(b))
+				bch_bucket_add_unused(ca, b);
 		}
 	}
 

drivers/md/bcache/extents.c

@@ -499,9 +499,9 @@ static bool bch_extent_bad_expensive(struct btree *b, const struct bkey *k,
 
 	if (mutex_trylock(&b->c->bucket_lock)) {
 		if (b->c->gc_mark_valid &&
-		    ((GC_MARK(g) != GC_MARK_DIRTY &&
-		      KEY_DIRTY(k)) ||
-		     GC_MARK(g) == GC_MARK_METADATA))
+		    (!GC_MARK(g) ||
+		     GC_MARK(g) == GC_MARK_METADATA ||
+		     (GC_MARK(g) != GC_MARK_DIRTY && KEY_DIRTY(k))))
 			goto err;
 
 		if (g->prio == BTREE_PRIO)