Re: [PATCH 02/18] xfs: don't create overlapping extents in xfs_bmap_add_extent_delay_real

[Brian Foster <bfoster@redhat.com>]

On Tue, Oct 31, 2017 at 04:22:14PM +0200, Christoph Hellwig wrote:
> Two cases in xfs_bmap_add_extent_delay_real currently insert a new
> extent before updating the existing one that is being split.  While
> this works fine with a simple extent list, a more complex tree can't
> easily cope with overlapping extent.  Reshuffle the code a bit to update
> the slot of the existing delalloc extent to the new real extent before
> inserting the shortened delalloc extent before or after it.  This
> avoids the overlapping extents while still allowing to update the
> br_startblock field of the delalloc extent with the updated indirect
> block reservation.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

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

>  fs/xfs/libxfs/xfs_bmap.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index b2b6832b9e6b..0eda6892b9d0 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1790,7 +1790,7 @@ xfs_bmap_add_extent_delay_real(
>  		 * Filling in the first part of a previous delayed allocation.
>  		 * The left neighbor is not contiguous.
>  		 */
> -		xfs_iext_insert(bma->ip, bma->idx, 1, new, state);
> +		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
>  		(*nextents)++;
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> @@ -1823,7 +1823,7 @@ xfs_bmap_add_extent_delay_real(
>  		PREV.br_startoff = new_endoff;
>  		PREV.br_blockcount = temp;
>  		PREV.br_startblock = nullstartblock(da_new);
> -		xfs_iext_update_extent(bma->ip, state, bma->idx + 1, &PREV);
> +		xfs_iext_insert(bma->ip, bma->idx + 1, 1, &PREV, state);
>  		break;
>  
>  	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
> @@ -1866,7 +1866,7 @@ xfs_bmap_add_extent_delay_real(
>  		 * Filling in the last part of a previous delayed allocation.
>  		 * The right neighbor is not contiguous.
>  		 */
> -		xfs_iext_insert(bma->ip, bma->idx + 1, 1, new, state);
> +		xfs_iext_update_extent(bma->ip, state, bma->idx, new);
>  		(*nextents)++;
>  		if (bma->cur == NULL)
>  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> @@ -1898,7 +1898,7 @@ xfs_bmap_add_extent_delay_real(
>  
>  		PREV.br_startblock = nullstartblock(da_new);
>  		PREV.br_blockcount = temp;
> -		xfs_iext_update_extent(bma->ip, state, bma->idx, &PREV);
> +		xfs_iext_insert(bma->ip, bma->idx, 1, &PREV, state);
>  
>  		bma->idx++;
>  		break;
> -- 
> 2.14.2
> 
> --
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