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.
Thanks,
Miklos
>
> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
> ---
> fs/overlayfs/inode.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 28c71978eb2e..17d1add0af1a 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -31,12 +31,6 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> goto out;
>
> if (attr->ia_valid & ATTR_SIZE) {
> - struct inode *realinode = d_inode(ovl_dentry_real(dentry));
> -
> - err = -ETXTBSY;
> - if (atomic_read(&realinode->i_writecount) < 0)
> - goto out_drop_write;
> -
> /* Truncate should trigger data copy up as well */
> full_copy_up = true;
> }
> --
> 2.27.0
>
>
