---- 在 星期二, 2021-07-20 23:19:16 Miklos Szeredi <miklos@xxxxxxxxxx> 撰写 ---- > On Tue, 20 Jul 2021 at 16:35, Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > > > On Sat, 24 Apr 2021 at 16:04, Chengguang Xu <cgxu519@xxxxxxxxxxxx> wrote: > > > > > > Lower files may be shared in overlayfs so strictly checking write > > > perssmion on lower file will cause interferes between different > > > overlayfs instances. > > > > How so? > > > > i_writecount on lower inode is not modified by overlayfs (at least not > > in this codepath). Which means that there should be no interference > > between overlayfs instances sharing a lower directory tree. > > I'm beginning to see what you are worrying about. > > So on one instance a file on lower gets executed and on another > instance sharing the lower layer the file is truncated. The truncate > is currently denied due to the negative i_writecount on the lower > file. Also behavior is inconsistent between open(path, O_TRUNC) and > truncate(path) even though the two should be equivalent. Yeah, that's it. Thanks for applying the patch and supplementary description. Thanks, Chengguang
