Re: [PATCH v2 2/3] smb/server: deny overwriting targets with non-POSIX opens

> +bool ksmbd_has_other_nonposix_open(struct dentry *dentry)
> +{
> +       struct ksmbd_file *fp;
> +       struct ksmbd_inode *ci;
> +       struct inode *inode = d_inode(dentry);
> +       bool ret = false;
> +
> +       if (!inode)
> +               return false;
> +
> +       ci = ksmbd_inode_lookup_lock(dentry);
The new check is limited to the target dentry's
ksmbd_inode->m_fp_list. Therefore, it does not cover a struct
ksmbd_file opened through another hardlink dentry, even though
file_inode(fp->filp) == d_inode(dentry). For example, if file2.link is
a hardlink to file2 and file2.link is opened with a non-POSIX context,
an overwrite rename of another file to file2 can miss that open
handle.
This appears to be an existing limitation rather than a regression
introduced by this patch. However, since this patch is intended to
reject overwrites when the target has a non-POSIX ksmbd_file...

> +       if (!ci)
> +               return false;
> +
> +       down_read(&ci->m_lock);
> +       list_for_each_entry(fp, &ci->m_fp_list, node) {
> +               if (READ_ONCE(fp->f_state) != FP_INITED)
> +                       continue;
> +               if (inode != file_inode(fp->filp))
> +                       continue;
> +               if (fp->is_posix_ctxt)
> +                       continue;
> +
> +               ret = true;
> +               break;
> +       }
> +       up_read(&ci->m_lock);
> +       ksmbd_inode_put(ci);