bcachefs: Improved check_directory_structure()

Now that we have inode backpointers, we can simplify checking directory
structure: instead of doing a DFS from the filesystem root and then
checking if we found everything, we can iterate over every inode and see
if we can go up until we get to the root.

This patch also has a number of fixes and simplifications for the inode
backpointer checks. Also, it turns out we don't actually need the
BCH_INODE_BACKPTR_UNTRUSTED flag.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_update.h

@@ -103,13 +103,12 @@ static inline int bch2_trans_commit(struct btree_trans *trans,
 	return __bch2_trans_commit(trans);
 }
 
-#define __bch2_trans_do(_trans, _disk_res, _journal_seq, _flags, _do)	\
+#define lockrestart_do(_trans, _do)					\
 ({									\
 	int _ret;							\
 									\
 	while (1) {							\
-		_ret = (_do) ?:	bch2_trans_commit(_trans, (_disk_res),	\
-					(_journal_seq), (_flags));	\
+		_ret = (_do);						\
 		if (_ret != -EINTR)					\
 			break;						\
 		bch2_trans_reset(_trans, 0);				\
@@ -118,6 +117,10 @@ static inline int bch2_trans_commit(struct btree_trans *trans,
 	_ret;								\
 })
 
+#define __bch2_trans_do(_trans, _disk_res, _journal_seq, _flags, _do)	\
+	lockrestart_do(_trans, _do ?: bch2_trans_commit(_trans, (_disk_res),\
+					(_journal_seq), (_flags)))
+
 #define bch2_trans_do(_c, _disk_res, _journal_seq, _flags, _do)		\
 ({									\
 	struct btree_trans trans;					\

fs/bcachefs/fs-common.c

@@ -110,8 +110,6 @@ int bch2_link_trans(struct btree_trans *trans, u64 dir_inum,
 	inode_u->bi_ctime = now;
 	bch2_inode_nlink_inc(inode_u);
 
-	inode_u->bi_flags |= BCH_INODE_BACKPTR_UNTRUSTED;
-
 	dir_iter = bch2_inode_peek(trans, dir_u, dir_inum, 0);
 	ret = PTR_ERR_OR_ZERO(dir_iter);
 	if (ret)
@@ -175,6 +173,12 @@ int bch2_unlink_trans(struct btree_trans *trans,
 	if (ret)
 		goto err;
 
+	if (inode_u->bi_dir		== k.k->p.inode &&
+	    inode_u->bi_dir_offset	== k.k->p.offset) {
+		inode_u->bi_dir		= 0;
+		inode_u->bi_dir_offset	= 0;
+	}
+
 	dir_u->bi_mtime = dir_u->bi_ctime = inode_u->bi_ctime = now;
 	dir_u->bi_nlink -= S_ISDIR(inode_u->bi_mode);
 	bch2_inode_nlink_dec(inode_u);

fs/bcachefs/inode.c

@@ -307,7 +307,7 @@ struct btree_iter *bch2_inode_peek(struct btree_trans *trans,
 	if (ret)
 		goto err;
 
-	ret = k.k->type == KEY_TYPE_inode ? 0 : -EIO;
+	ret = k.k->type == KEY_TYPE_inode ? 0 : -ENOENT;
 	if (ret)
 		goto err;
 
@@ -637,39 +637,18 @@ int bch2_inode_rm(struct bch_fs *c, u64 inode_nr, bool cached)
 	return ret;
 }
 
-int __bch2_inode_find_by_inum_trans(struct btree_trans *trans, u64 inode_nr,
-				    struct bch_inode_unpacked *inode,
-				    unsigned flags)
+static int bch2_inode_find_by_inum_trans(struct btree_trans *trans, u64 inode_nr,
+					 struct bch_inode_unpacked *inode)
 {
 	struct btree_iter *iter;
-	struct bkey_s_c k;
 	int ret;
 
-	iter = bch2_trans_get_iter(trans, BTREE_ID_inodes,
-			POS(0, inode_nr), flags);
-	k = (flags & BTREE_ITER_TYPE) == BTREE_ITER_CACHED
-		? bch2_btree_iter_peek_cached(iter)
-		: bch2_btree_iter_peek_slot(iter);
-	ret = bkey_err(k);
-	if (ret)
-		goto err;
-
-	ret = k.k->type == KEY_TYPE_inode
-		? bch2_inode_unpack(bkey_s_c_to_inode(k), inode)
-		: -ENOENT;
-err:
+	iter = bch2_inode_peek(trans, inode, inode_nr, 0);
+	ret = PTR_ERR_OR_ZERO(iter);
 	bch2_trans_iter_put(trans, iter);
 	return ret;
 }
 
-int bch2_inode_find_by_inum_trans(struct btree_trans *trans, u64 inode_nr,
-				  struct bch_inode_unpacked *inode)
-{
-	return __bch2_inode_find_by_inum_trans(trans, inode_nr,
-					       inode, BTREE_ITER_CACHED);
-
-}
-
 int bch2_inode_find_by_inum(struct bch_fs *c, u64 inode_nr,
 			    struct bch_inode_unpacked *inode)
 {

fs/bcachefs/inode.h

@@ -74,10 +74,6 @@ struct btree_iter *bch2_inode_create(struct btree_trans *,
 
 int bch2_inode_rm(struct bch_fs *, u64, bool);
 
-int __bch2_inode_find_by_inum_trans(struct btree_trans *, u64,
-				    struct bch_inode_unpacked *, unsigned);
-int bch2_inode_find_by_inum_trans(struct btree_trans *, u64,
-				  struct bch_inode_unpacked *);
 int bch2_inode_find_by_inum(struct bch_fs *, u64, struct bch_inode_unpacked *);
 
 static inline struct bch_io_opts bch2_inode_opts_get(struct bch_inode_unpacked *inode)