bcachefs: check inode backpointer in bch2_lookup()

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

diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 5624c2ea8d55a41bdcb97e1fabcb786272e8d870..138d416a64d5aec6df4727a1734f885a5bb6f26d 100644 (file)
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -400,6 +400,7 @@ static struct bch_inode_info *bch2_lookup_trans(struct btree_trans *trans,
        struct bch_fs *c = trans->c;
        struct btree_iter dirent_iter = {};
        subvol_inum inum = {};
+       struct printbuf buf = PRINTBUF;
 
        struct bkey_s_c k = bch2_hash_lookup(trans, &dirent_iter, bch2_dirent_hash_desc,
                                             dir_hash_info, dir, name, 0);
@@ -426,20 +427,31 @@ static struct bch_inode_info *bch2_lookup_trans(struct btree_trans *trans,
        ret =   bch2_subvolume_get(trans, inum.subvol, true, 0, &subvol) ?:
                bch2_inode_find_by_inum_nowarn_trans(trans, inum, &inode_u) ?:
                PTR_ERR_OR_ZERO(inode = bch2_new_inode(trans));
-       if (bch2_err_matches(ret, ENOENT)) {
-               struct printbuf buf = PRINTBUF;
 
-               bch2_bkey_val_to_text(&buf, c, k);
-               bch_err(c, "%s points to missing inode", buf.buf);
-               printbuf_exit(&buf);
-       }
+       bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT),
+                               c, "dirent to missing inode:\n  %s",
+                               (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
        if (ret)
                goto err;
 
+       /* regular files may have hardlinks: */
+       if (bch2_fs_inconsistent_on(bch2_inode_should_have_bp(&inode_u) &&
+                                   !bkey_eq(k.k->p, POS(inode_u.bi_dir, inode_u.bi_dir_offset)),
+                                   c,
+                                   "dirent points to inode that does not point back:\n  %s",
+                                   (bch2_bkey_val_to_text(&buf, c, k),
+                                    prt_printf(&buf, "\n  "),
+                                    bch2_inode_unpacked_to_text(&buf, &inode_u),
+                                    buf.buf))) {
+               ret = -ENOENT;
+               goto err;
+       }
+
        bch2_vfs_inode_init(trans, inum, inode, &inode_u, &subvol);
        inode = bch2_inode_insert(c, inode);
 out:
        bch2_trans_iter_exit(trans, &dirent_iter);
+       printbuf_exit(&buf);
        return inode;
 err:
        inode = ERR_PTR(ret);