From: "J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [PATCH] Fix nfsd rewrite performance
Date: Mon, 1 Aug 2005 07:53:19 -0400
Message-ID: <20050801115319.GD6497@fieldses.org>
References: <20050801113954.GA8698@suse.de>
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Cc: nfs@lists.sourceforge.net
To: Olaf Kirch <okir@suse.de>
In-Reply-To: <20050801113954.GA8698@suse.de>
Sender: nfs-admin@lists.sourceforge.net
Errors-To: nfs-admin@lists.sourceforge.net

I haven't had the chance to read carefully; just one quick question:

On Mon, Aug 01, 2005 at 01:39:54PM +0200, Olaf Kirch wrote:
> +	this_page = (unsigned char *) vec[vlen-1].iov_base;
> +	for (i = vlen-1; i; --i) {
> +		prev_page = (unsigned char *) vec[i-1].iov_base;
> +
> +		/* Push trailing partial page so it's
> +		 * aligned with the end of the page, then
> +		 * pull up the missing chunk from the previous
> +		 * page */
> +		memmove(this_page + chunk0, this_page, chunk1);
> +		memcpy(this_page, prev_page + chunk1, chunk0);
> +		vec[i].iov_len = PAGE_CACHE_SIZE;
> +		this_page = prev_page;
> +	}

If there's stuff after the write data (as there could be in the NFSv4
case at least), does this overwrite it?

--b.


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