linux-kernel - Re: [PATCH 05/39] vfs: optionally don't account file in nr

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Message-ID: <20180604084739.GD11333@infradead.org>
Date:   Mon, 4 Jun 2018 01:47:39 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Miklos Szeredi <mszeredi@...hat.com>
Cc:     linux-unionfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/39] vfs: optionally don't account file in nr_files

On Tue, May 29, 2018 at 04:43:05PM +0200, Miklos Szeredi wrote:
> Stacking file operations in overlay will store an extra open file for each
> overlay file opened.
> 
> The overhead is just that of "struct file" which is about 256bytes, because
> overlay already pins an extra dentry and inode when the file is open, which
> add up to a much larger overhead.

But that overhead is exactly what nr_files accounts for, so this looks
bogus to me.