bcachefs: Throttle updates when btree key cache is too dirty

This is needed to ensure we don't deadlock because journal reclaim and
thus memory reclaim isn't making forward progress.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/bcachefs/btree_key_cache.h b/fs/bcachefs/btree_key_cache.h
index 7723a2178430..d7d31a0662c3 100644
--- a/fs/bcachefs/btree_key_cache.h
+++ b/fs/bcachefs/btree_key_cache.h
@@ -5,11 +5,20 @@ static inline size_t bch2_nr_btree_keys_need_flush(struct bch_fs *c)
 {
 	size_t nr_dirty = READ_ONCE(c->btree_key_cache.nr_dirty);
 	size_t nr_keys = READ_ONCE(c->btree_key_cache.nr_dirty);
-	size_t max_dirty = 1024 + (nr_keys * 3) / 4;
+	size_t max_dirty = 4096 + nr_keys  / 2;
 
 	return max_t(ssize_t, 0, nr_dirty - max_dirty);
 }
 
+static inline bool bch2_btree_key_cache_must_wait(struct bch_fs *c)
+{
+	size_t nr_dirty = READ_ONCE(c->btree_key_cache.nr_dirty);
+	size_t nr_keys = READ_ONCE(c->btree_key_cache.nr_dirty);
+	size_t max_dirty = 4096 + (nr_keys * 3) / 4;
+
+	return nr_dirty > max_dirty;
+}
+
 struct bkey_cached *
 bch2_btree_key_cache_find(struct bch_fs *, enum btree_id, struct bpos);