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Commit bc9389ee authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Avoid deadlocking in garbage collection 



Not a complete fix - we could still deadlock if btree_insert_node() has
to split...

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent a1f0358b

drivers/md/bcache/btree.c

+11 −10
Original line number Diff line number Diff line
@@ -1059,14 +1059,14 @@ static void btree_node_free(struct btree *b) 
	mutex_unlock(&b->c->bucket_lock);

}



struct btree *bch_btree_node_alloc(struct cache_set *c, int level)

struct btree *bch_btree_node_alloc(struct cache_set *c, int level, bool wait)

{

	BKEY_PADDED(key) k;

	struct btree *b = ERR_PTR(-EAGAIN);



	mutex_lock(&c->bucket_lock);

retry:

	if (__bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, true))

	if (__bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, wait))

		goto err;



	bkey_put(c, &k.key);
@@ -1098,9 +1098,9 @@ struct btree *bch_btree_node_alloc(struct cache_set *c, int level) 
	return b;

}



static struct btree *btree_node_alloc_replacement(struct btree *b)

static struct btree *btree_node_alloc_replacement(struct btree *b, bool wait)

{

	struct btree *n = bch_btree_node_alloc(b->c, b->level);

	struct btree *n = bch_btree_node_alloc(b->c, b->level, wait);

	if (!IS_ERR_OR_NULL(n))

		bch_btree_sort_into(b, n);
@@ -1250,7 +1250,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, 
		return 0;



	for (i = 0; i < nodes; i++) {

		new_nodes[i] = btree_node_alloc_replacement(r[i].b);

		new_nodes[i] = btree_node_alloc_replacement(r[i].b, false);

		if (IS_ERR_OR_NULL(new_nodes[i]))

			goto out_nocoalesce;

	}
@@ -1420,7 +1420,8 @@ static int btree_gc_recurse(struct btree *b, struct btree_op *op, 
		if (!IS_ERR(last->b)) {

			should_rewrite = btree_gc_mark_node(last->b, gc);

			if (should_rewrite) {

				n = btree_node_alloc_replacement(last->b);

				n = btree_node_alloc_replacement(last->b,

								 false);



				if (!IS_ERR_OR_NULL(n)) {

					bch_btree_node_write_sync(n);
@@ -1492,7 +1493,7 @@ static int bch_btree_gc_root(struct btree *b, struct btree_op *op, 


	should_rewrite = btree_gc_mark_node(b, gc);

	if (should_rewrite) {

		n = btree_node_alloc_replacement(b);

		n = btree_node_alloc_replacement(b, false);



		if (!IS_ERR_OR_NULL(n)) {

			bch_btree_node_write_sync(n);
@@ -2038,7 +2039,7 @@ static int btree_split(struct btree *b, struct btree_op *op, 


	closure_init_stack(&cl);



	n1 = btree_node_alloc_replacement(b);

	n1 = btree_node_alloc_replacement(b, true);

	if (IS_ERR(n1))

		goto err;
@@ -2049,12 +2050,12 @@ static int btree_split(struct btree *b, struct btree_op *op, 


		trace_bcache_btree_node_split(b, n1->sets[0].data->keys);



		n2 = bch_btree_node_alloc(b->c, b->level);

		n2 = bch_btree_node_alloc(b->c, b->level, true);

		if (IS_ERR(n2))

			goto err_free1;



		if (!b->parent) {

			n3 = bch_btree_node_alloc(b->c, b->level + 1);

			n3 = bch_btree_node_alloc(b->c, b->level + 1, true);

			if (IS_ERR(n3))

				goto err_free2;

		}

drivers/md/bcache/btree.h

+1 −1
Original line number Diff line number Diff line
@@ -271,7 +271,7 @@ void bch_btree_node_read(struct btree *); 
void bch_btree_node_write(struct btree *, struct closure *);



void bch_btree_set_root(struct btree *);

struct btree *bch_btree_node_alloc(struct cache_set *, int);

struct btree *bch_btree_node_alloc(struct cache_set *, int, bool);

struct btree *bch_btree_node_get(struct cache_set *, struct bkey *, int, bool);



int bch_btree_insert_check_key(struct btree *, struct btree_op *,

drivers/md/bcache/super.c

+1 −1
Original line number Diff line number Diff line
@@ -1601,7 +1601,7 @@ static void run_cache_set(struct cache_set *c) 
			goto err;



		err = "cannot allocate new btree root";

		c->root = bch_btree_node_alloc(c, 0);

		c->root = bch_btree_node_alloc(c, 0, true);

		if (IS_ERR_OR_NULL(c->root))

			goto err;