Re: [PATCH 12/18] xfs: refactor xfs_bmap_add_extent_delay_real

[Brian Foster <bfoster@redhat.com>]

On Fri, Sep 15, 2017 at 07:54:20AM -0700, Christoph Hellwig wrote:
> Use xfs_iext_get_extent to find, and xfs_iext_update_extent to update
> entries in the in-core extent list.  This isolates the function from
> the detailed layout of the extent list, and generally makes the code
> a lot more readable.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/libxfs/xfs_bmap.c | 181 +++++++++++++++++++++++++----------------------
>  1 file changed, 95 insertions(+), 86 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 4fb73c0aca05..8606a775c94b 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
...
> @@ -2078,16 +2095,8 @@ xfs_bmap_add_extent_delay_real(
>  				goto done;
>  		}
>  
> -		ep = xfs_iext_get_ext(ifp, bma->idx);
> -		xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));
> -		trace_xfs_bmap_post_update(bma->ip, bma->idx, state, _THIS_IP_);
> -		trace_xfs_bmap_pre_update(bma->ip, bma->idx + 2, state, _THIS_IP_);
> -		xfs_bmbt_set_startblock(xfs_iext_get_ext(ifp, bma->idx + 2),
> -			nullstartblock((int)temp2));
> -		trace_xfs_bmap_post_update(bma->ip, bma->idx + 2, state, _THIS_IP_);
> -
>  		bma->idx++;
> -		da_new = temp + temp2;
> +		da_new = PREV.br_blockcount + RIGHT.br_blockcount;

da_new should be the new total indirect reservation. The above sets it
to the total/remaining delalloc block count. E.g., it should probably be
something like this:

	da_new = startblockval(PREV.br_startblock) +
		 startblockval(RIGHT.br_startblock);

Or alternatively you could set da_new right before diff is calculated
and reuse it in that calculation. Otherwise the patch looks good.

Brian

>  		break;
>  
>  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
> -- 
> 2.14.1
> 
> --
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