Commit d6fd3b11 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Explicitly track btree node's parent 



This is prep work for the reworked btree insertion code.

The way we set b->parent is ugly and hacky... the problem is, when
btree_split() or garbage collection splits or rewrites a btree node, the
parent changes for all its (potentially already cached) children.

I may change this later and add some code to look through the btree node
cache and find all our cached child nodes and change the parent pointer
then...

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent 8304ad4d

drivers/md/bcache/btree.c

+10 −4
Original line number Diff line number Diff line
@@ -884,6 +884,7 @@ out: 


	lock_set_subclass(&b->lock.dep_map, level + 1, _THIS_IP_);

	b->level	= level;

	b->parent	= (void *) ~0UL;



	mca_reinit(b);
@@ -1898,7 +1899,7 @@ out: 


static int btree_split(struct btree *b, struct btree_op *op)

{

	bool split, root = b == b->c->root;

	bool split;

	struct btree *n1, *n2 = NULL, *n3 = NULL;

	uint64_t start_time = local_clock();
@@ -1920,7 +1921,7 @@ static int btree_split(struct btree *b, struct btree_op *op) 
		if (IS_ERR(n2))

			goto err_free1;



		if (root) {

		if (!b->parent) {

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

			if (IS_ERR(n3))

				goto err_free2;
@@ -1928,7 +1929,8 @@ static int btree_split(struct btree *b, struct btree_op *op) 


		bch_btree_insert_keys(n1, op);



		/* Has to be a linear search because we don't have an auxiliary

		/*

		 * Has to be a linear search because we don't have an auxiliary

		 * search tree yet

		 */
@@ -1960,6 +1962,8 @@ static int btree_split(struct btree *b, struct btree_op *op) 
	bch_btree_node_write(n1, &op->cl);



	if (n3) {

		/* Depth increases, make a new root */



		bkey_copy_key(&n3->key, &MAX_KEY);

		bch_btree_insert_keys(n3, op);

		bch_btree_node_write(n3, &op->cl);
@@ -1967,7 +1971,9 @@ static int btree_split(struct btree *b, struct btree_op *op) 
		closure_sync(&op->cl);

		bch_btree_set_root(n3);

		rw_unlock(true, n3);

	} else if (root) {

	} else if (!b->parent) {

		/* Root filled up but didn't need to be split */



		op->keys.top = op->keys.bottom;

		closure_sync(&op->cl);

		bch_btree_set_root(n1);

drivers/md/bcache/btree.h

+10 −6
Original line number Diff line number Diff line
@@ -125,6 +125,7 @@ struct btree { 
	unsigned long		seq;

	struct rw_semaphore	lock;

	struct cache_set	*c;

	struct btree		*parent;



	unsigned long		flags;

	uint16_t		written;	/* would be nice to kill */
@@ -327,12 +328,13 @@ static inline void rw_unlock(bool w, struct btree *b) 
({									\

	int _r, l = (b)->level - 1;					\

	bool _w = l <= (op)->lock;					\

	struct btree *_b = bch_btree_node_get((b)->c, key, l, op);	\

	if (!IS_ERR(_b)) {						\

		_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);		\

		rw_unlock(_w, _b);					\

	struct btree *_child = bch_btree_node_get((b)->c, key, l, op);	\

	if (!IS_ERR(_child)) {						\

		_child->parent = (b);					\

		_r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__);	\

		rw_unlock(_w, _child);					\

	} else								\

		_r = PTR_ERR(_b);					\

		_r = PTR_ERR(_child);					\

	_r;								\

})
@@ -350,8 +352,10 @@ static inline void rw_unlock(bool w, struct btree *b) 
		bool _w = insert_lock(op, _b);				\

		rw_lock(_w, _b, _b->level);				\

		if (_b == (c)->root &&					\

		    _w == insert_lock(op, _b))				\

		    _w == insert_lock(op, _b)) {			\

			_b->parent = NULL;				\

			_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);	\

		}							\

		rw_unlock(_w, _b);					\

		bch_cannibalize_unlock(c, &(op)->cl);			\

	} while (_r == -EINTR);						\

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