[PATCH 034/119] xfs: teach rmapbt to support interval queries

[Brian Foster]

On Thu, Jun 16, 2016 at 06:21:30PM -0700, Darrick J. Wong wrote:
> Now that the generic btree code supports querying all records within a
> range of keys, use that functionality to allow us to ask for all the
> extents mapped to a range of physical blocks.
> 
> v2: Move unwritten bit to rm_offset.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
> ---
>  fs/xfs/libxfs/xfs_rmap.c       |   43 ++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/libxfs/xfs_rmap_btree.h |    9 ++++++++
>  2 files changed, 52 insertions(+)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
> index c6a5a0b..0e1721a 100644
> --- a/fs/xfs/libxfs/xfs_rmap.c
> +++ b/fs/xfs/libxfs/xfs_rmap.c
> @@ -184,3 +184,46 @@ out_error:
>  	trace_xfs_rmap_alloc_extent_error(mp, agno, bno, len, false, oinfo);
>  	return error;
>  }
> +
> +struct xfs_rmapbt_query_range_info {
> +	xfs_rmapbt_query_range_fn	fn;
> +	void				*priv;
> +};
> +
> +/* Format btree record and pass to our callback. */
> +STATIC int
> +xfs_rmapbt_query_range_helper(
> +	struct xfs_btree_cur	*cur,
> +	union xfs_btree_rec	*rec,
> +	void			*priv)
> +{
> +	struct xfs_rmapbt_query_range_info	*query = priv;
> +	struct xfs_rmap_irec			irec;
> +	int					error;
> +
> +	error = xfs_rmapbt_btrec_to_irec(rec, &irec);
> +	if (error)
> +		return error;
> +	return query->fn(cur, &irec, query->priv);
> +}
> +
> +/* Find all rmaps between two keys. */
> +int
> +xfs_rmapbt_query_range(
> +	struct xfs_btree_cur		*cur,
> +	struct xfs_rmap_irec		*low_rec,
> +	struct xfs_rmap_irec		*high_rec,
> +	xfs_rmapbt_query_range_fn	fn,
> +	void				*priv)
> +{
> +	union xfs_btree_irec		low_brec;
> +	union xfs_btree_irec		high_brec;
> +	struct xfs_rmapbt_query_range_info	query;
> +
> +	low_brec.r = *low_rec;
> +	high_brec.r = *high_rec;

Some checks or asserts that these are actually in order couldn't hurt.
Otherwise looks good:

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

> +	query.priv = priv;
> +	query.fn = fn;
> +	return xfs_btree_query_range(cur, &low_brec, &high_brec,
> +			xfs_rmapbt_query_range_helper, &query);
> +}
> diff --git a/fs/xfs/libxfs/xfs_rmap_btree.h b/fs/xfs/libxfs/xfs_rmap_btree.h
> index 796071c..e926c6e 100644
> --- a/fs/xfs/libxfs/xfs_rmap_btree.h
> +++ b/fs/xfs/libxfs/xfs_rmap_btree.h
> @@ -74,4 +74,13 @@ int xfs_rmap_free(struct xfs_trans *tp, struct xfs_buf *agbp,
>  		  xfs_agnumber_t agno, xfs_agblock_t bno, xfs_extlen_t len,
>  		  struct xfs_owner_info *oinfo);
>  
> +typedef int (*xfs_rmapbt_query_range_fn)(
> +	struct xfs_btree_cur	*cur,
> +	struct xfs_rmap_irec	*rec,
> +	void			*priv);
> +
> +int xfs_rmapbt_query_range(struct xfs_btree_cur *cur,
> +		struct xfs_rmap_irec *low_rec, struct xfs_rmap_irec *high_rec,
> +		xfs_rmapbt_query_range_fn fn, void *priv);
> +
>  #endif	/* __XFS_RMAP_BTREE_H__ */
> 
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