From 62448afee714354a26db8a0f3c644f58628f0792 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Fri, 5 Aug 2022 13:06:44 -0400 Subject: bcachefs: Fix bch2_btree_node_upgrade() Previously, if we were trying to upgrade from a read to an intent lock but we held an additional read lock via another btree_path, bch2_btree_node_upgrade() would always fail, in six_lock_tryupgrade(). This patch factors out the code that __bch2_btree_node_lock_write() uses to temporarily drop extra read locks, so that six_lock_tryupgrade() can succeed. Signed-off-by: Kent Overstreet --- fs/bcachefs/btree_locking.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) (limited to 'fs') diff --git a/fs/bcachefs/btree_locking.c b/fs/bcachefs/btree_locking.c index 08dbc799bb35..5b6d8184ea45 100644 --- a/fs/bcachefs/btree_locking.c +++ b/fs/bcachefs/btree_locking.c @@ -230,6 +230,7 @@ bool bch2_btree_node_upgrade(struct btree_trans *trans, struct btree_path *path, unsigned level) { struct btree *b = path->l[level].b; + struct six_lock_count count = bch2_btree_node_lock_counts(trans, path, &b->c, level); if (!is_btree_node(path, level)) return false; @@ -253,11 +254,24 @@ bool bch2_btree_node_upgrade(struct btree_trans *trans, if (race_fault()) return false; - if (btree_node_locked(path, level) - ? six_lock_tryupgrade(&b->c.lock) - : six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq)) - goto success; + if (btree_node_locked(path, level)) { + bool ret; + + six_lock_readers_add(&b->c.lock, -count.n[SIX_LOCK_read]); + ret = six_lock_tryupgrade(&b->c.lock); + six_lock_readers_add(&b->c.lock, count.n[SIX_LOCK_read]); + + if (ret) + goto success; + } else { + if (six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq)) + goto success; + } + /* + * Do we already have an intent lock via another path? If so, just bump + * lock count: + */ if (btree_node_lock_seq_matches(path, b, level) && btree_node_lock_increment(trans, &b->c, level, BTREE_NODE_INTENT_LOCKED)) { btree_node_unlock(trans, path, level); -- cgit v1.2.3