xfs: implement masked btree key comparisons for _has_records scans

For keyspace fullness scans, we want to be able to mask off the parts of
the key that we don't care about.  For most btree types we /do/ want the
full keyspace, but for checking that a given space usage also has a full
complement of rmapbt records (even if different/multiple owners) we need
this masking so that we only track sparseness of rm_startblock, not the
whole keyspace (which is extremely sparse).

Augment the ->diff_two_keys and ->keys_contiguous helpers to take a
third union xfs_btree_key argument, and wire up xfs_rmap_has_records to
pass this through.  This third "mask" argument should contain a nonzero
value in each structure field that should be used in the key comparisons
done during the scan.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index e616b964f11c..308b81f321eb 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -2721,6 +2721,9 @@ xfs_rmap_has_records(
 	xfs_extlen_t		len,
 	enum xbtree_recpacking	*outcome)
 {
+	union xfs_btree_key	mask = {
+		.rmap.rm_startblock = cpu_to_be32(-1U),
+	};
 	union xfs_btree_irec	low;
 	union xfs_btree_irec	high;
 
@@ -2729,7 +2732,7 @@ xfs_rmap_has_records(
 	memset(&high, 0xFF, sizeof(high));
 	high.r.rm_startblock = bno + len - 1;
 
-	return xfs_btree_has_records(cur, &low, &high, outcome);
+	return xfs_btree_has_records(cur, &low, &high, &mask, outcome);
 }
 
 /*