bcachefs: Run check_dirents second time if required

If we move a key backwards, we'll need a second pass to run the rest of
the fsck checks.

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

Author: Kent Overstreet

fs/bcachefs/dirent.c

@@ -705,8 +705,9 @@ int bch2_readdir(struct bch_fs *c, subvol_inum inum,
 
 			subvol_inum target;
 
+			bool need_second_pass = false;
 			int ret2 = bch2_str_hash_check_key(trans, NULL, &bch2_dirent_hash_desc,
-							   hash_info, &iter, k) ?:
+							   hash_info, &iter, k, &need_second_pass) ?:
 				bch2_dirent_read_target(trans, inum, dirent, &target);
 			if (ret2 > 0)
 				continue;

fs/bcachefs/fsck.c

@@ -2141,7 +2141,8 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
 			struct bch_hash_info *hash_info,
 			struct inode_walker *dir,
 			struct inode_walker *target,
-			struct snapshots_seen *s)
+			struct snapshots_seen *s,
+			bool *need_second_pass)
 {
 	struct bch_fs *c = trans->c;
 	struct inode_walker_entry *i;
@@ -2183,7 +2184,8 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
 		*hash_info = bch2_hash_info_init(c, &i->inode);
 	dir->first_this_inode = false;
 
-	ret = bch2_str_hash_check_key(trans, s, &bch2_dirent_hash_desc, hash_info, iter, k);
+	ret = bch2_str_hash_check_key(trans, s, &bch2_dirent_hash_desc, hash_info,
+				      iter, k, need_second_pass);
 	if (ret < 0)
 		goto err;
 	if (ret) {
@@ -2228,7 +2230,8 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
 						    STR_HASH_must_create) ?:
 			bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc);
 
-		/* might need another check_dirents pass */
+		if (dir_offset < k.k->p.offset)
+			*need_second_pass = true;
 		goto out;
 	}
 
@@ -2296,7 +2299,6 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
 err:
 fsck_err:
 	printbuf_exit(&buf);
-	bch_err_fn(c, ret);
 	return ret;
 }
 
@@ -2310,17 +2312,30 @@ int bch2_check_dirents(struct bch_fs *c)
 	struct inode_walker target = inode_walker_init();
 	struct snapshots_seen s;
 	struct bch_hash_info hash_info;
+	bool need_second_pass = false, did_second_pass = false;
 
 	snapshots_seen_init(&s);
-
+again:
 	int ret = bch2_trans_run(c,
 		for_each_btree_key_commit(trans, iter, BTREE_ID_dirents,
 				POS(BCACHEFS_ROOT_INO, 0),
 				BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
 				NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
-			check_dirent(trans, &iter, k, &hash_info, &dir, &target, &s)) ?:
+			check_dirent(trans, &iter, k, &hash_info, &dir, &target, &s,
+				     &need_second_pass)) ?:
 		check_subdir_count_notnested(trans, &dir));
 
+	if (!ret && need_second_pass && !did_second_pass) {
+		bch_info(c, "check_dirents requires second pass");
+		swap(did_second_pass, need_second_pass);
+		goto again;
+	}
+
+	if (!ret && need_second_pass) {
+		bch_err(c, "dirents not repairing");
+		ret = -EINVAL;
+	}
+
 	snapshots_seen_exit(&s);
 	inode_walker_exit(&dir);
 	inode_walker_exit(&target);
@@ -2334,16 +2349,14 @@ static int check_xattr(struct btree_trans *trans, struct btree_iter *iter,
 		       struct inode_walker *inode)
 {
 	struct bch_fs *c = trans->c;
-	struct inode_walker_entry *i;
-	int ret;
 
-	ret = bch2_check_key_has_snapshot(trans, iter, k);
+	int ret = bch2_check_key_has_snapshot(trans, iter, k);
 	if (ret < 0)
 		return ret;
 	if (ret)
 		return 0;
 
-	i = walk_inode(trans, inode, k);
+	struct inode_walker_entry *i = walk_inode(trans, inode, k);
 	ret = PTR_ERR_OR_ZERO(i);
 	if (ret)
 		return ret;
@@ -2359,9 +2372,9 @@ static int check_xattr(struct btree_trans *trans, struct btree_iter *iter,
 		*hash_info = bch2_hash_info_init(c, &i->inode);
 	inode->first_this_inode = false;
 
-	ret = bch2_str_hash_check_key(trans, NULL, &bch2_xattr_hash_desc, hash_info, iter, k);
-	bch_err_fn(c, ret);
-	return ret;
+	bool need_second_pass = false;
+	return bch2_str_hash_check_key(trans, NULL, &bch2_xattr_hash_desc, hash_info,
+				      iter, k, &need_second_pass);
 }
 
 /*

fs/bcachefs/str_hash.c

@@ -35,7 +35,8 @@ static noinline int fsck_rename_dirent(struct btree_trans *trans,
 				       struct snapshots_seen *s,
 				       const struct bch_hash_desc desc,
 				       struct bch_hash_info *hash_info,
-				       struct bkey_s_c_dirent old)
+				       struct bkey_s_c_dirent old,
+				       bool *updated_before_k_pos)
 {
 	struct qstr old_name = bch2_dirent_get_name(old);
 	struct bkey_i_dirent *new = bch2_trans_kmalloc(trans, bkey_bytes(old.k) + 32);
@@ -62,16 +63,15 @@ static noinline int fsck_rename_dirent(struct btree_trans *trans,
 						old.k->p.snapshot, &new->k_i,
 						BTREE_UPDATE_internal_snapshot_node);
 		if (ret && !bch2_err_matches(ret, EEXIST))
-			goto err;
-		if (!ret)
 			break;
+		if (!ret) {
+			if (bpos_lt(new->k.p, old.k->p))
+				*updated_before_k_pos = true;
+			break;
+		}
 	}
 
-	if (ret)
-		goto err;
-
-	ret = bch2_fsck_update_backpointers(trans, s, desc, hash_info, &new->k_i);
-err:
+	ret = ret ?: bch2_fsck_update_backpointers(trans, s, desc, hash_info, &new->k_i);
 	bch_err_fn(trans->c, ret);
 	return ret;
 }
@@ -230,7 +230,8 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 			      struct snapshots_seen *s,
 			      const struct bch_hash_desc *desc,
 			      struct bch_hash_info *hash_info,
-			      struct btree_iter *k_iter, struct bkey_s_c hash_k)
+			      struct btree_iter *k_iter, struct bkey_s_c hash_k,
+			      bool *updated_before_k_pos)
 {
 	struct bch_fs *c = trans->c;
 	struct btree_iter iter = {};
@@ -310,6 +311,9 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 		if (k.k)
 			goto duplicate_entries;
 
+		if (bpos_lt(new->k.p, k.k->p))
+			*updated_before_k_pos = true;
+
 		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,
@@ -345,7 +349,8 @@ int __bch2_str_hash_check_key(struct btree_trans *trans,
 		ret = bch2_hash_delete_at(trans, *desc, hash_info, &iter, 0);
 		break;
 	case 2:
-		ret = fsck_rename_dirent(trans, s, *desc, hash_info, bkey_s_c_to_dirent(hash_k)) ?:
+		ret = fsck_rename_dirent(trans, s, *desc, hash_info, bkey_s_c_to_dirent(hash_k),
+					 updated_before_k_pos) ?:
 			bch2_hash_delete_at(trans, *desc, hash_info, k_iter, 0);
 		goto out;
 	}

fs/bcachefs/str_hash.h

@@ -402,21 +402,24 @@ int __bch2_str_hash_check_key(struct btree_trans *,
 			      struct snapshots_seen *,
 			      const struct bch_hash_desc *,
 			      struct bch_hash_info *,
-			      struct btree_iter *, struct bkey_s_c);
+			      struct btree_iter *, struct bkey_s_c,
+			      bool *);
 
 static inline int bch2_str_hash_check_key(struct btree_trans *trans,
 			    struct snapshots_seen *s,
 			    const struct bch_hash_desc *desc,
 			    struct bch_hash_info *hash_info,
-			    struct btree_iter *k_iter, struct bkey_s_c hash_k)
+			    struct btree_iter *k_iter, struct bkey_s_c hash_k,
+			    bool *updated_before_k_pos)
 {
 	if (hash_k.k->type != desc->key_type)
 		return 0;
 
 	if (likely(desc->hash_bkey(hash_info, hash_k) == hash_k.k->p.offset))
 		return 0;
 
-	return __bch2_str_hash_check_key(trans, s, desc, hash_info, k_iter, hash_k);
+	return __bch2_str_hash_check_key(trans, s, desc, hash_info, k_iter, hash_k,
+					 updated_before_k_pos);
 }
 
 #endif /* _BCACHEFS_STR_HASH_H */