Commit be9e782d authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Don't downgrade locks on transaction restart 



We should only be downgrading locks on success - otherwise, our
transaction restarts won't be getting the correct locks and we'll
livelock.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 2e7acdfb

fs/bcachefs/btree_iter.c

+2 −1
Original line number Diff line number Diff line
@@ -1523,6 +1523,7 @@ static inline struct btree_path *btree_path_alloc(struct btree_trans *trans, 
	path->ref		= 0;

	path->intent_ref	= 0;

	path->nodes_locked	= 0;

	path->alloc_seq++;



	btree_path_list_add(trans, pos, path);

	trans->paths_sorted = false;
@@ -1598,7 +1599,7 @@ struct btree_path *bch2_path_get(struct btree_trans *trans, 


	locks_want = min(locks_want, BTREE_MAX_DEPTH);

	if (locks_want > path->locks_want)

		bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want);

		bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want, NULL);



	return path;

}

fs/bcachefs/btree_key_cache.c

+1 −1
Original line number Diff line number Diff line
@@ -509,7 +509,7 @@ bch2_btree_path_traverse_cached_slowpath(struct btree_trans *trans, struct btree 
		 * path->uptodate yet:

		 */

		if (!path->locks_want &&

		    !__bch2_btree_path_upgrade(trans, path, 1)) {

		    !__bch2_btree_path_upgrade(trans, path, 1, NULL)) {

			trace_and_count(trans->c, trans_restart_key_cache_upgrade, trans, _THIS_IP_);

			ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_upgrade);

			goto err;

fs/bcachefs/btree_locking.c

+29 −9
Original line number Diff line number Diff line
@@ -431,7 +431,8 @@ void bch2_btree_node_lock_write_nofail(struct btree_trans *trans, 


static inline bool btree_path_get_locks(struct btree_trans *trans,

					struct btree_path *path,

					bool upgrade)

					bool upgrade,

					struct get_locks_fail *f)

{

	unsigned l = path->level;

	int fail_idx = -1;
@@ -442,9 +443,15 @@ static inline bool btree_path_get_locks(struct btree_trans *trans, 


		if (!(upgrade

		      ? bch2_btree_node_upgrade(trans, path, l)

		      : bch2_btree_node_relock(trans, path, l)))

		      : bch2_btree_node_relock(trans, path, l))) {

			fail_idx	= l;



			if (f) {

				f->l	= l;

				f->b	= path->l[l].b;

			}

		}



		l++;

	} while (l < path->locks_want);
@@ -584,7 +591,9 @@ __flatten 
bool bch2_btree_path_relock_norestart(struct btree_trans *trans,

			struct btree_path *path, unsigned long trace_ip)

{

	return btree_path_get_locks(trans, path, false);

	struct get_locks_fail f;



	return btree_path_get_locks(trans, path, false, &f);

}



int __bch2_btree_path_relock(struct btree_trans *trans,
@@ -600,22 +609,24 @@ int __bch2_btree_path_relock(struct btree_trans *trans, 


bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *trans,

			       struct btree_path *path,

			       unsigned new_locks_want)

			       unsigned new_locks_want,

			       struct get_locks_fail *f)

{

	EBUG_ON(path->locks_want >= new_locks_want);



	path->locks_want = new_locks_want;



	return btree_path_get_locks(trans, path, true);

	return btree_path_get_locks(trans, path, true, f);

}



bool __bch2_btree_path_upgrade(struct btree_trans *trans,

			       struct btree_path *path,

			       unsigned new_locks_want)

			       unsigned new_locks_want,

			       struct get_locks_fail *f)

{

	struct btree_path *linked;



	if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want))

	if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want, f))

		return true;



	/*
@@ -644,7 +655,7 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans, 
			    linked->btree_id == path->btree_id &&

			    linked->locks_want < new_locks_want) {

				linked->locks_want = new_locks_want;

				btree_path_get_locks(trans, linked, true);

				btree_path_get_locks(trans, linked, true, NULL);

			}



	return false;
@@ -656,6 +667,9 @@ void __bch2_btree_path_downgrade(struct btree_trans *trans, 
{

	unsigned l;



	if (trans->restarted)

		return;



	EBUG_ON(path->locks_want < new_locks_want);



	path->locks_want = new_locks_want;
@@ -674,6 +688,9 @@ void __bch2_btree_path_downgrade(struct btree_trans *trans, 
	}



	bch2_btree_path_verify_locks(path);



	path->downgrade_seq++;

	trace_path_downgrade(trans, _RET_IP_, path);

}



/* Btree transaction locking: */
@@ -682,6 +699,9 @@ void bch2_trans_downgrade(struct btree_trans *trans) 
{

	struct btree_path *path;



	if (trans->restarted)

		return;



	trans_for_each_path(trans, path)

		bch2_btree_path_downgrade(trans, path);

}

fs/bcachefs/btree_locking.h

+14 −4
Original line number Diff line number Diff line
@@ -355,26 +355,36 @@ static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans, 


/* upgrade */





struct get_locks_fail {

	unsigned	l;

	struct btree	*b;

};



bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *,

			       struct btree_path *, unsigned);

			       struct btree_path *, unsigned,

			       struct get_locks_fail *);



bool __bch2_btree_path_upgrade(struct btree_trans *,

			       struct btree_path *, unsigned);

			       struct btree_path *, unsigned,

			       struct get_locks_fail *);



static inline int bch2_btree_path_upgrade(struct btree_trans *trans,

					  struct btree_path *path,

					  unsigned new_locks_want)

{

	struct get_locks_fail f;

	unsigned old_locks_want = path->locks_want;



	new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH);



	if (path->locks_want < new_locks_want

	    ? __bch2_btree_path_upgrade(trans, path, new_locks_want)

	    ? __bch2_btree_path_upgrade(trans, path, new_locks_want, &f)

	    : path->uptodate == BTREE_ITER_UPTODATE)

		return 0;



	trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path,

			old_locks_want, new_locks_want);

			old_locks_want, new_locks_want, &f);

	return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade);

}

fs/bcachefs/btree_trans_commit.c

+3 −6
Original line number Diff line number Diff line
@@ -861,12 +861,7 @@ static inline int do_bch2_trans_commit(struct btree_trans *trans, unsigned flags 
	 */

	bch2_journal_res_put(&c->journal, &trans->journal_res);



	if (unlikely(ret))

	return ret;



	bch2_trans_downgrade(trans);



	return 0;

}



static int journal_reclaim_wait_done(struct bch_fs *c)
@@ -1135,6 +1130,8 @@ int __bch2_trans_commit(struct btree_trans *trans, unsigned flags) 
	if (likely(!(flags & BTREE_INSERT_NOCHECK_RW)))

		bch2_write_ref_put(c, BCH_WRITE_REF_trans);

out_reset:

	if (!ret)

		bch2_trans_downgrade(trans);

	bch2_trans_reset_updates(trans);



	return ret;