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, 32 insertions, 15 deletions

diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index 66beb87caf1a..6c81b20e97d2 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -273,31 +273,43 @@ STATIC int64_t
 xfs_rmapbt_diff_two_keys(
 	struct xfs_btree_cur		*cur,
 	const union xfs_btree_key	*k1,
-	const union xfs_btree_key	*k2)
+	const union xfs_btree_key	*k2,
+	const union xfs_btree_key	*mask)
 {
 	const struct xfs_rmap_key	*kp1 = &k1->rmap;
 	const struct xfs_rmap_key	*kp2 = &k2->rmap;
 	int64_t				d;
 	__u64				x, y;
 
+	/* Doesn't make sense to mask off the physical space part */
+	ASSERT(!mask || mask->rmap.rm_startblock);
+
 	d = (int64_t)be32_to_cpu(kp1->rm_startblock) -
-		       be32_to_cpu(kp2->rm_startblock);
+		     be32_to_cpu(kp2->rm_startblock);
 	if (d)
 		return d;
 
-	x = be64_to_cpu(kp1->rm_owner);
-	y = be64_to_cpu(kp2->rm_owner);
-	if (x > y)
-		return 1;
-	else if (y > x)
-		return -1;
+	if (!mask || mask->rmap.rm_owner) {
+		x = be64_to_cpu(kp1->rm_owner);
+		y = be64_to_cpu(kp2->rm_owner);
+		if (x > y)
+			return 1;
+		else if (y > x)
+			return -1;
+	}
+
+	if (!mask || mask->rmap.rm_offset) {
+		/* Doesn't make sense to allow offset but not owner */
+		ASSERT(!mask || mask->rmap.rm_owner);
+
+		x = offset_keymask(be64_to_cpu(kp1->rm_offset));
+		y = offset_keymask(be64_to_cpu(kp2->rm_offset));
+		if (x > y)
+			return 1;
+		else if (y > x)
+			return -1;
+	}
 
-	x = offset_keymask(be64_to_cpu(kp1->rm_offset));
-	y = offset_keymask(be64_to_cpu(kp2->rm_offset));
-	if (x > y)
-		return 1;
-	else if (y > x)
-		return -1;
 	return 0;
 }
 
@@ -448,13 +460,18 @@ STATIC enum xbtree_key_contig
 xfs_rmapbt_keys_contiguous(
 	struct xfs_btree_cur		*cur,
 	const union xfs_btree_key	*key1,
-	const union xfs_btree_key	*key2)
+	const union xfs_btree_key	*key2,
+	const union xfs_btree_key	*mask)
 {
+	ASSERT(!mask || mask->rmap.rm_startblock);
+
 	/*
 	 * We only support checking contiguity of the physical space component.
 	 * If any callers ever need more specificity than that, they'll have to
 	 * implement it here.
 	 */
+	ASSERT(!mask || (!mask->rmap.rm_owner && !mask->rmap.rm_offset));
+
 	return xbtree_key_contig(be32_to_cpu(key1->rmap.rm_startblock),
 				 be32_to_cpu(key2->rmap.rm_startblock));
 }