[Ocfs2-devel] [PATCH 23/25] xfs: fix pagecache truncation prior to reflink

[Dave Chinner]

On Wed, Oct 10, 2018 at 09:15:12PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong at oracle.com>
> 
> Prior to remapping blocks, it is necessary to remove pages from the
> destination file's page cache.  Unfortunately, the truncation is not
> aggressive enough -- if page size > block size, we'll end up zeroing
> subpage blocks instead of removing them.  So, round the start offset
> down and the end offset up to page boundaries.  We already wrote all
> the dirty data so the larger range shouldn't be a problem.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
> ---
>  fs/xfs/xfs_reflink.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> 
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index b24a2a1c4db1..e1592e751cc2 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1370,8 +1370,9 @@ xfs_reflink_remap_prep(
>  		goto out_unlock;
>  
>  	/* Zap any page cache for the destination file's range. */
> -	truncate_inode_pages_range(&inode_out->i_data, pos_out,
> -				   PAGE_ALIGN(pos_out + *len) - 1);
> +	truncate_inode_pages_range(&inode_out->i_data,
> +			round_down(pos_out, PAGE_SIZE),
> +			round_up(pos_out + *len, PAGE_SIZE) - 1);

Looks good.

Reviewed-by: Dave Chinner <dchinner at redhat.com>
-- 
Dave Chinner
david at fromorbit.com