[PATCH 3/6] xfs: don't zero partial page cache pages during O_DIRECT writes

[Brian Foster]

On Thu, Aug 21, 2014 at 03:09:11PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> Similar to direct IO reads, direct IO writes are using
> truncate_pagecache_range to invalidate the page cache. This is
> incorrect due to the sub-block zeroing in the page cache that
> truncate_pagecache_range() triggers.
> 
> This patch fixes things by using invalidate_inode_pages2_range
> instead.  It preserves the page cache invalidation, but won't zero
> any pages.
> 
> cc: stable at vger.kernel.org
> Signed-off-by: Dave Chinner <dchinner at redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster at redhat.com>

>  fs/xfs/xfs_file.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 827cfb2..19917fa 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -644,7 +644,15 @@ xfs_file_dio_aio_write(
>  						    pos, -1);
>  		if (ret)
>  			goto out;
> -		truncate_pagecache_range(VFS_I(ip), pos, -1);
> +		/*
> +		 * Invalidate whole pages. This can return an error if
> +		 * we fail to invalidate a page, but this should never
> +		 * happen on XFS. Warn if it does fail.
> +		 */
> +		ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
> +						pos >> PAGE_CACHE_SHIFT, -1);
> +		WARN_ON_ONCE(ret);
> +		ret = 0;
>  	}
>  
>  	/*
> -- 
> 2.0.0
> 
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