bcachefs: bch2_str_hash_check_key() may now be called without snapshots_seen

We don't track snapshot overwrites outside of fsck, so for this to be
called at runtime outside of fsck we need to create it on demand, when
we have repair to do.

Signed-off-by: Kent Overstreet <[email protected]>

Author: Kent Overstreet

fs/bcachefs/fsck.c

@@ -643,11 +643,6 @@ static int reconstruct_inode(struct btree_trans *trans, enum btree_id btree, u32
 	return __bch2_fsck_write_inode(trans, &new_inode);
 }
 
-struct snapshots_seen {
-	struct bpos			pos;
-	snapshot_id_list		ids;
-};
-
 static inline void snapshots_seen_exit(struct snapshots_seen *s)
 {
 	darray_exit(&s->ids);

fs/bcachefs/fsck.h

@@ -4,6 +4,12 @@
 
 #include "str_hash.h"
 
+/* recoverds snapshot IDs of overwrites at @pos */
+struct snapshots_seen {
+	struct bpos			pos;
+	snapshot_id_list		ids;
+};
+
 int bch2_fsck_update_backpointers(struct btree_trans *,
 				  struct snapshots_seen *,
 				  const struct bch_hash_desc,

fs/bcachefs/str_hash.c

@@ -231,6 +231,7 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 	struct btree_iter iter = {};
 	struct printbuf buf = PRINTBUF;
 	struct bkey_s_c k;
+	bool free_snapshots_seen = false;
 	int ret = 0;
 
 	u64 hash = desc->hash_bkey(hash_info, hash_k);
@@ -256,6 +257,8 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 out:
 	bch2_trans_iter_exit(trans, &iter);
 	printbuf_exit(&buf);
+	if (free_snapshots_seen)
+		darray_exit(&s->ids);
 	return ret;
 bad_hash:
 	/*
@@ -265,6 +268,22 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 	if (ret)
 		goto out;
 
+	if (!s) {
+		s = bch2_trans_kmalloc(trans, sizeof(*s));
+		ret = PTR_ERR_OR_ZERO(s);
+		if (ret)
+			goto out;
+
+		s->pos = k_iter->pos;
+		darray_init(&s->ids);
+
+		ret = bch2_get_snapshot_overwrites(trans, desc->btree_id, k_iter->pos, &s->ids);
+		if (ret)
+			goto out;
+
+		free_snapshots_seen = true;
+	}
+
 	if (fsck_err(trans, hash_table_key_wrong_offset,
 		     "hash table key at wrong offset: btree %s inode %llu offset %llu, hashed to %llu\n%s",
 		     bch2_btree_id_str(desc->btree_id), hash_k.k->p.inode, hash_k.k->p.offset, hash,
@@ -286,7 +305,9 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 		if (k.k)
 			goto duplicate_entries;
 
-		ret =   bch2_hash_delete_at(trans, *desc, hash_info, k_iter,
+		ret =   bch2_insert_snapshot_whiteouts(trans, desc->btree_id,
+						       k_iter->pos, new->k.p) ?:
+			bch2_hash_delete_at(trans, *desc, hash_info, k_iter,
 					    BTREE_ITER_with_updates|
 					    BTREE_UPDATE_internal_snapshot_node) ?:
 			bch2_fsck_update_backpointers(trans, s, *desc, hash_info, new) ?: