[PATCH 04/18] bcachefs: Rework bch2_check_lru_key()

[Kent Overstreet <kent.overstreet@linux.dev>]

It's now easier to add new LRU types.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/lru.c | 77 +++++++++++++++++++++++++++++------------------
 1 file changed, 47 insertions(+), 30 deletions(-)

diff --git a/fs/bcachefs/lru.c b/fs/bcachefs/lru.c
index dc6b9a80a8b5..98ab8496f29d 100644
--- a/fs/bcachefs/lru.c
+++ b/fs/bcachefs/lru.c
@@ -116,49 +116,67 @@ int bch2_lru_check_set(struct btree_trans *trans,
 	return ret;
 }
 
+static struct bbpos lru_pos_to_bp(struct bkey_s_c lru_k)
+{
+	enum bch_lru_type type = lru_type(lru_k);
+
+	switch (type) {
+	case BCH_LRU_read:
+	case BCH_LRU_fragmentation:
+		return BBPOS(BTREE_ID_alloc, u64_to_bucket(lru_k.k->p.offset));
+	default:
+		BUG();
+	}
+}
+
+static u64 bkey_lru_type_idx(struct bch_fs *c,
+			     enum bch_lru_type type,
+			     struct bkey_s_c k)
+{
+	struct bch_alloc_v4 a_convert;
+	const struct bch_alloc_v4 *a;
+
+	switch (type) {
+	case BCH_LRU_read:
+		a = bch2_alloc_to_v4(k, &a_convert);
+		return alloc_lru_idx_read(*a);
+	case BCH_LRU_fragmentation: {
+		a = bch2_alloc_to_v4(k, &a_convert);
+
+		rcu_read_lock();
+		struct bch_dev *ca = bch2_dev_rcu_noerror(c, k.k->p.inode);
+		u64 idx = ca
+			? alloc_lru_idx_fragmentation(*a, ca)
+			: 0;
+		rcu_read_unlock();
+		return idx;
+	}
+	default:
+		BUG();
+	}
+}
+
 static int bch2_check_lru_key(struct btree_trans *trans,
 			      struct btree_iter *lru_iter,
 			      struct bkey_s_c lru_k,
 			      struct bkey_buf *last_flushed)
 {
 	struct bch_fs *c = trans->c;
-	struct btree_iter iter;
-	struct bkey_s_c k;
-	struct bch_alloc_v4 a_convert;
-	const struct bch_alloc_v4 *a;
 	struct printbuf buf1 = PRINTBUF;
 	struct printbuf buf2 = PRINTBUF;
-	enum bch_lru_type type = lru_type(lru_k);
-	struct bpos alloc_pos = u64_to_bucket(lru_k.k->p.offset);
-	u64 idx;
-	int ret;
-
-	struct bch_dev *ca = bch2_dev_bucket_tryget_noerror(c, alloc_pos);
 
-	if (fsck_err_on(!ca,
-			trans, lru_entry_to_invalid_bucket,
-			"lru key points to nonexistent device:bucket %llu:%llu",
-			alloc_pos.inode, alloc_pos.offset))
-		return bch2_btree_bit_mod_buffered(trans, BTREE_ID_lru, lru_iter->pos, false);
+	struct bbpos bp = lru_pos_to_bp(lru_k);
 
-	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_alloc, alloc_pos, 0);
-	ret = bkey_err(k);
+	struct btree_iter iter;
+	struct bkey_s_c k = bch2_bkey_get_iter(trans, &iter, bp.btree, bp.pos, 0);
+	int ret = bkey_err(k);
 	if (ret)
 		goto err;
 
-	a = bch2_alloc_to_v4(k, &a_convert);
-
-	switch (type) {
-	case BCH_LRU_read:
-		idx = alloc_lru_idx_read(*a);
-		break;
-	case BCH_LRU_fragmentation:
-		idx = alloc_lru_idx_fragmentation(*a, ca);
-		break;
-	}
+	enum bch_lru_type type = lru_type(lru_k);
+	u64 idx = bkey_lru_type_idx(c, type, k);
 
-	if (lru_k.k->type != KEY_TYPE_set ||
-	    lru_pos_time(lru_k.k->p) != idx) {
+	if (lru_pos_time(lru_k.k->p) != idx) {
 		ret = bch2_btree_write_buffer_maybe_flush(trans, lru_k, last_flushed);
 		if (ret)
 			goto err;
@@ -176,7 +194,6 @@ static int bch2_check_lru_key(struct btree_trans *trans,
 err:
 fsck_err:
 	bch2_trans_iter_exit(trans, &iter);
-	bch2_dev_put(ca);
 	printbuf_exit(&buf2);
 	printbuf_exit(&buf1);
 	return ret;
-- 
2.45.2