linux-kernel - Re: still nfs problems [Was: Linux 2.6.37-rc8]

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Date:	Wed, 05 Jan 2011 16:39:47 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Trond Myklebust <Trond.Myklebust@...app.com>
CC:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	linux-nfs@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Marc Kleine-Budde <m.kleine-budde@...gutronix.de>,
	stable@...nel.org
Subject: Re: still nfs problems [Was: Linux 2.6.37-rc8]

On 01/05/2011 04:29 PM, Trond Myklebust wrote:
> On Wed, 2011-01-05 at 10:14 -0500, Trond Myklebust wrote: 
>> OK. So,the new behaviour in 2.6.37 is that we're writing to a series of
>> pages via the usual kmap_atomic()/kunmap_atomic() and kmap()/kunmap()
>> interfaces, but we can end up reading them via a virtual address range
>> that gets set up via vm_map_ram() (that range gets set up before the
>> write occurs).
>>
>> Do we perhaps need an invalidate_kernel_vmap_range() before we can read
>> the data on ARM in this kind of scenario?
> 
> IOW: Does something like the following patch fix the problem?
> 
> ------------------------------------------------------------------------------- 
> From: Trond Myklebust <Trond.Myklebust@...app.com>
> NFS: Ensure we clean the TLB cache in nfs_readdir_xdr_to_array
>     
> After calling nfs_readdir_xdr_filler(), we need a call to
> invalidate_kernel_vmap_range() before we can proceed to read
> the data back through the virtual address range.
>     
> Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
> ---
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 996dd89..4640470 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -587,6 +587,9 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
>  		if (status < 0)
>  			break;
>  		pglen = status;
> +
> +		invalidate_kernel_vmap_range(pages_ptr, pglen);
> +
>  		status = nfs_readdir_page_filler(desc, &entry, pages_ptr, page, pglen);
>  		if (status < 0) {
>  			if (status == -ENOSPC)

\o/ - Works for me (at91, armv5)

Tested-by: Marc Kleine-Budde <mkl@...gutronix.de>

This is a candidate for stable (Cc'd).

Regards,
Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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