Re: [PATCH 03/18] xfs: treat idx as a cursor in xfs_bmap_add_extent_delay_real

[Brian Foster <bfoster@redhat.com>]

On Tue, Oct 31, 2017 at 04:22:15PM +0200, Christoph Hellwig wrote:
> Stop poking before and after the index and just increment or decrement
> it while doing our operations on it to prepare for a new extent list
> implementation.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/libxfs/xfs_bmap.c | 27 ++++++++++++++++-----------
>  1 file changed, 16 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 0eda6892b9d0..83f5a503dce1 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
...
> @@ -1762,12 +1766,14 @@ xfs_bmap_add_extent_delay_real(
>  				startblockval(PREV.br_startblock));
>  
>  		LEFT.br_blockcount += new->br_blockcount;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx - 1, &LEFT);
>  
>  		PREV.br_blockcount = temp = PREV.br_blockcount - new->br_blockcount;

Unrelated to this patch, but this ^ line looks funny. We've already
assigned temp to this value just a few lines above. That might be worth
cleaning up if this requires a v2. Otherwise this looks fine:

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

>  		PREV.br_startoff += new->br_blockcount;
>  		PREV.br_startblock = nullstartblock(da_new);
> +
>  		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		bma->idx--;
> +		xfs_iext_update_extent(bma->ip, state, bma->idx, &LEFT);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1782,7 +1788,6 @@ xfs_bmap_add_extent_delay_real(
>  				goto done;
>  		}
>  
> -		bma->idx--;
>  		break;
>  
>  	case BMAP_LEFT_FILLING:
> @@ -1835,7 +1840,6 @@ xfs_bmap_add_extent_delay_real(
>  		RIGHT.br_startoff = new->br_startoff;
>  		RIGHT.br_startblock = new->br_startblock;
>  		RIGHT.br_blockcount += new->br_blockcount;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx + 1, &RIGHT);
>  
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_DEXT;
> @@ -1856,9 +1860,10 @@ xfs_bmap_add_extent_delay_real(
>  
>  		PREV.br_blockcount = temp;
>  		PREV.br_startblock = nullstartblock(da_new);
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
>  
> +		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
>  		bma->idx++;
> +		xfs_iext_update_extent(bma->ip, state, bma->idx, &RIGHT);
>  		break;
>  
>  	case BMAP_RIGHT_FILLING:
> -- 
> 2.14.2
> 
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