bcachefs: Add (partial) support for fixing btree topology

When we walk the btrees during recovery, part of that is checking that
btree topology is correct: for every interior btree node, its child
nodes should exactly span the range the parent node covers.

Previously, we had checks for this, but not repair code. Now that we
have the ability to do btree updates during initial GC, this patch adds
that repair code.

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

1 files changed, 34 insertions, 9 deletions

diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c
index 4b29be7234c7..443d669e6a30 100644
--- a/fs/bcachefs/btree_cache.c
+++ b/fs/bcachefs/btree_cache.c
@@ -7,6 +7,7 @@
 #include "btree_iter.h"
 #include "btree_locking.h"
 #include "debug.h"
+#include "error.h"
 #include "trace.h"
 
 #include <linux/prefetch.h>
@@ -813,9 +814,12 @@ lock_node:
 		return ERR_PTR(-EIO);
 	}
 
-	EBUG_ON(b->c.btree_id != iter->btree_id ||
-		BTREE_NODE_LEVEL(b->data) != level ||
-		bkey_cmp(b->data->max_key, k->k.p));
+	EBUG_ON(b->c.btree_id != iter->btree_id);
+	EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
+	EBUG_ON(bkey_cmp(b->data->max_key, k->k.p));
+	EBUG_ON(b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
+		bkey_cmp(b->data->min_key,
+			 bkey_i_to_btree_ptr_v2(&b->key)->v.min_key));
 
 	return b;
 }
@@ -823,7 +827,8 @@ lock_node:
 struct btree *bch2_btree_node_get_noiter(struct bch_fs *c,
 					 const struct bkey_i *k,
 					 enum btree_id btree_id,
-					 unsigned level)
+					 unsigned level,
+					 bool nofill)
 {
 	struct btree_cache *bc = &c->btree_cache;
 	struct btree *b;
@@ -838,6 +843,9 @@ struct btree *bch2_btree_node_get_noiter(struct bch_fs *c,
 retry:
 	b = btree_cache_find(bc, k);
 	if (unlikely(!b)) {
+		if (nofill)
+			return NULL;
+
 		b = bch2_btree_node_fill(c, NULL, k, btree_id,
 					 level, SIX_LOCK_read, true);
 
@@ -884,9 +892,12 @@ lock_node:
 		return ERR_PTR(-EIO);
 	}
 
-	EBUG_ON(b->c.btree_id != btree_id ||
-		BTREE_NODE_LEVEL(b->data) != level ||
-		bkey_cmp(b->data->max_key, k->k.p));
+	EBUG_ON(b->c.btree_id != btree_id);
+	EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
+	EBUG_ON(bkey_cmp(b->data->max_key, k->k.p));
+	EBUG_ON(b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
+		bkey_cmp(b->data->min_key,
+			 bkey_i_to_btree_ptr_v2(&b->key)->v.min_key));
 
 	return b;
 }
@@ -996,8 +1007,22 @@ out:
 		if (sib != btree_prev_sib)
 			swap(n1, n2);
 
-		BUG_ON(bkey_cmp(bkey_successor(n1->key.k.p),
-				n2->data->min_key));
+		if (bkey_cmp(bkey_successor(n1->key.k.p),
+			     n2->data->min_key)) {
+			char buf1[200], buf2[200];
+
+			bch2_bkey_val_to_text(&PBUF(buf1), c, bkey_i_to_s_c(&n1->key));
+			bch2_bkey_val_to_text(&PBUF(buf2), c, bkey_i_to_s_c(&n2->key));
+
+			bch2_fs_inconsistent(c, "btree topology error at btree %s level %u:\n"
+					     "prev: %s\n"
+					     "next: %s\n",
+					     bch2_btree_ids[iter->btree_id], level,
+					     buf1, buf2);
+
+			six_unlock_intent(&ret->c.lock);
+			ret = NULL;
+		}
 	}
 
 	bch2_btree_trans_verify_locks(trans);