document-portal: Don't invalidate directories

This fixes issue flatpak#1234. This is a followup from flatpak#1190.

fuse_lowlevel_notify_inval_entry() will invalidate directories too,
which is a problem as it invalidate the current workdir directory.
So now we don't invalidate them and will let the kernel deal with it.

This is consistent with the passthrough_hp example from fuse.

Signed-off-by: Hubert Figuière <hub@figuiere.net>

document-portal/document-portal-fuse.c

@@ -109,7 +109,7 @@
  * referenced by the dcache (Directory Entry Cache) (even though we
  * will not really use the dcache info due to the 0 valid time). This
  * is unfortunate, because it means we will keep a lot of file
- * descriptor open. But, we can not know if the kernel needs the inode
+ * descriptors open. But, we can not know if the kernel needs the inode
  * for some non-dcache use so we can't close the file descriptors.
  *
  * To work around this we regularly emit entry invalidation calls
@@ -947,7 +947,7 @@ verify_doc_dir_devino (int dirfd, XdpDomain *doc_domain)
     return -ENOENT;
 
   return 0;
- }
+}
 
 /* Only for toplevel dirs, not this is a bit weird for toplevel dir
    inodes as it returns the dir itself which isn't really the dirfd
@@ -1659,7 +1659,7 @@ ensure_docdir_inode (XdpInode *parent,
         inode->domain_root_inode = xdp_inode_ref (parent->domain_root_inode);
       else
         inode->domain_root_inode = xdp_inode_ref (parent);
-     g_hash_table_insert (domain->inodes, physical, inode);
+      g_hash_table_insert (domain->inodes, physical, inode);
     }
   G_UNLOCK(domain_inodes);
 
@@ -1847,17 +1847,21 @@ xdp_fuse_lookup (fuse_req_t req,
     }
   else
     {
+      g_autoptr(XdpInode) inode = NULL;
+      struct stat buf;
+
       g_assert (parent_domain->type == XDP_DOMAIN_DOCUMENT);
 
       fd = xdp_document_inode_open_child_fd (parent, name, open_flags, 0);
       if (fd < 0)
         return xdp_reply_err (op, req, -fd);
 
-      res = ensure_docdir_inode (parent, fd, &e, NULL); /* Takes ownership of fd */
+      res = ensure_docdir_inode (parent, fd, &e, &inode); /* Takes ownership of fd */
       if (res != 0)
         return xdp_reply_err (op, req, -res);
 
-      queue_invalidate_dentry (parent, name);
+      if (fstat (inode->physical->fd, &buf) != 0 || !S_ISDIR(buf.st_mode))
+        queue_invalidate_dentry (parent, name);
     }
 
   g_debug ("LOOKUP %lx:%s => %lx", parent_ino, name, e.ino);
@@ -2360,7 +2364,7 @@ xdp_fuse_opendir (fuse_req_t             req,
         }
     }
 
-   fi->fh = (gsize)d;
+  fi->fh = (gsize)d;
 
   if (fuse_reply_open (req, fi) == -ENOENT)
     {