Re: [PATCH] mm,fs,dax: mark dax_iomap_pmd_fault as const

From: Dave Jiang <dave.jiang@intel.com>
To: Arnd Bergmann <arnd@arndb.de>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Matthew Wilcox <mawilcox@microsoft.com>,
	Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dave Chinner <dchinner@redhat.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm,fs,dax: mark dax_iomap_pmd_fault as const
Date: Mon, 27 Feb 2017 13:38:55 -0700	[thread overview]
Message-ID: <03239288-0aff-98b7-e176-4954ecc6359c@intel.com> (raw)
In-Reply-To: <20170227203349.3318733-1-arnd@arndb.de>

On 02/27/2017 01:33 PM, Arnd Bergmann wrote:
> The two alternative implementations of dax_iomap_fault have different
> prototypes, and one of them is obviously wrong as seen from this build
> warning:
> 
> fs/dax.c: In function 'dax_iomap_fault':
> fs/dax.c:1462:35: error: passing argument 2 of 'dax_iomap_pmd_fault' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
> 
> This marks the argument 'const' as in all the related functions.
> 
> Fixes: a2d581675d48 ("mm,fs,dax: change ->pmd_fault to ->huge_fault")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks Arnd. I posted the same fix this morning. :)
http://marc.info/?l=linux-mm&m=148821429608976&w=2

> ---
>  fs/dax.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index d5712f42a2e6..85479428518f 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1436,7 +1436,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf,
>  	return result;
>  }
>  #else
> -static int dax_iomap_pmd_fault(struct vm_fault *vmf, struct iomap_ops *ops)
> +static int dax_iomap_pmd_fault(struct vm_fault *vmf, const struct iomap_ops *ops)
>  {
>  	return VM_FAULT_FALLBACK;
>  }
> 