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From: Colin Walters <walters@verbum.org>
To: Jan Kara <jack@suse.cz>, "Wangkai (Kevin,C)" <wangkai86@huawei.com>
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Date: Fri, 25 Aug 2017 11:10:03 -0400
Subject: Re: [PATCH] fs/dcache: dentries should free after files unlinked or
 directories removed
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On Fri, Aug 25, 2017, at 10:47 AM, Jan Kara wrote:
> 
> It is possible that some of these dentries are so rarely used that they are
> indeed just a waste 

In some cases - think containers, or ostree-style root filesystem snapshots,
if we do an `rm -rf /path/to/container-root`, userspace knows for a fact
that nothing will reference those paths again - all of the processes that could
have been killed.  There's no point to having negative dentries for them.

Maybe something like unlinkat (dfd, path, AT_UNLINKAT_DONTNEED), like
madvise (MAV_DONTNEED) ?