xfs: refactor ->diff_two_keys callsites

Create wrapper functions around ->diff_two_keys so that we don't have to
remember what the return values mean, and adjust some of the code
comments to reflect the longtime code behavior.  We're going to
introduce more uses of ->diff_two_keys in the next patch, so reduce the
cognitive load for readers by doing this refactoring now.

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

Author: Darrick J. Wong

fs/xfs/libxfs/xfs_btree.c

@@ -2067,8 +2067,7 @@ xfs_btree_get_leaf_keys(
 		for (n = 2; n <= xfs_btree_get_numrecs(block); n++) {
 			rec = xfs_btree_rec_addr(cur, n, block);
 			cur->bc_ops->init_high_key_from_rec(&hkey, rec);
-			if (cur->bc_ops->diff_two_keys(cur, &hkey, &max_hkey)
-					> 0)
+			if (xfs_btree_keycmp_gt(cur, &hkey, &max_hkey))
 				max_hkey = hkey;
 		}
 
@@ -2096,7 +2095,7 @@ xfs_btree_get_node_keys(
 		max_hkey = xfs_btree_high_key_addr(cur, 1, block);
 		for (n = 2; n <= xfs_btree_get_numrecs(block); n++) {
 			hkey = xfs_btree_high_key_addr(cur, n, block);
-			if (cur->bc_ops->diff_two_keys(cur, hkey, max_hkey) > 0)
+			if (xfs_btree_keycmp_gt(cur, hkey, max_hkey))
 				max_hkey = hkey;
 		}
 
@@ -2183,8 +2182,8 @@ __xfs_btree_updkeys(
 		nlkey = xfs_btree_key_addr(cur, ptr, block);
 		nhkey = xfs_btree_high_key_addr(cur, ptr, block);
 		if (!force_all &&
-		    !(cur->bc_ops->diff_two_keys(cur, nlkey, lkey) != 0 ||
-		      cur->bc_ops->diff_two_keys(cur, nhkey, hkey) != 0))
+		    xfs_btree_keycmp_eq(cur, nlkey, lkey) &&
+		    xfs_btree_keycmp_eq(cur, nhkey, hkey))
 			break;
 		xfs_btree_copy_keys(cur, nlkey, lkey, 1);
 		xfs_btree_log_keys(cur, bp, ptr, ptr);
@@ -4716,7 +4715,6 @@ xfs_btree_simple_query_range(
 {
 	union xfs_btree_rec		*recp;
 	union xfs_btree_key		rec_key;
-	int64_t				diff;
 	int				stat;
 	bool				firstrec = true;
 	int				error;
@@ -4746,20 +4744,17 @@ xfs_btree_simple_query_range(
 		if (error || !stat)
 			break;
 
-		/* Skip if high_key(rec) < low_key. */
+		/* Skip if low_key > high_key(rec). */
 		if (firstrec) {
 			cur->bc_ops->init_high_key_from_rec(&rec_key, recp);
 			firstrec = false;
-			diff = cur->bc_ops->diff_two_keys(cur, low_key,
-					&rec_key);
-			if (diff > 0)
+			if (xfs_btree_keycmp_gt(cur, low_key, &rec_key))
 				goto advloop;
 		}
 
-		/* Stop if high_key < low_key(rec). */
+		/* Stop if low_key(rec) > high_key. */
 		cur->bc_ops->init_key_from_rec(&rec_key, recp);
-		diff = cur->bc_ops->diff_two_keys(cur, &rec_key, high_key);
-		if (diff > 0)
+		if (xfs_btree_keycmp_gt(cur, &rec_key, high_key))
 			break;
 
 		/* Callback */
@@ -4813,8 +4808,6 @@ xfs_btree_overlapped_query_range(
 	union xfs_btree_key		*hkp;
 	union xfs_btree_rec		*recp;
 	struct xfs_btree_block		*block;
-	int64_t				ldiff;
-	int64_t				hdiff;
 	int				level;
 	struct xfs_buf			*bp;
 	int				i;
@@ -4854,25 +4847,23 @@ xfs_btree_overlapped_query_range(
 					block);
 
 			cur->bc_ops->init_high_key_from_rec(&rec_hkey, recp);
-			ldiff = cur->bc_ops->diff_two_keys(cur, &rec_hkey,
-					low_key);
-
 			cur->bc_ops->init_key_from_rec(&rec_key, recp);
-			hdiff = cur->bc_ops->diff_two_keys(cur, high_key,
-					&rec_key);
 
 			/*
+			 * If (query's high key < record's low key), then there
+			 * are no more interesting records in this block.  Pop
+			 * up to the leaf level to find more record blocks.
+			 *
 			 * If (record's high key >= query's low key) and
 			 *    (query's high key >= record's low key), then
 			 * this record overlaps the query range; callback.
 			 */
-			if (ldiff >= 0 && hdiff >= 0) {
+			if (xfs_btree_keycmp_lt(cur, high_key, &rec_key))
+				goto pop_up;
+			if (xfs_btree_keycmp_ge(cur, &rec_hkey, low_key)) {
 				error = fn(cur, recp, priv);
 				if (error)
 					break;
-			} else if (hdiff < 0) {
-				/* Record is larger than high key; pop. */
-				goto pop_up;
 			}
 			cur->bc_levels[level].ptr++;
 			continue;
@@ -4884,15 +4875,18 @@ xfs_btree_overlapped_query_range(
 				block);
 		pp = xfs_btree_ptr_addr(cur, cur->bc_levels[level].ptr, block);
 
-		ldiff = cur->bc_ops->diff_two_keys(cur, hkp, low_key);
-		hdiff = cur->bc_ops->diff_two_keys(cur, high_key, lkp);
-
 		/*
+		 * If (query's high key < pointer's low key), then there are no
+		 * more interesting keys in this block.  Pop up one leaf level
+		 * to continue looking for records.
+		 *
 		 * If (pointer's high key >= query's low key) and
 		 *    (query's high key >= pointer's low key), then
 		 * this record overlaps the query range; follow pointer.
 		 */
-		if (ldiff >= 0 && hdiff >= 0) {
+		if (xfs_btree_keycmp_lt(cur, high_key, lkp))
+			goto pop_up;
+		if (xfs_btree_keycmp_ge(cur, hkp, low_key)) {
 			level--;
 			error = xfs_btree_lookup_get_block(cur, level, pp,
 					&block);
@@ -4907,9 +4901,6 @@ xfs_btree_overlapped_query_range(
 #endif
 			cur->bc_levels[level].ptr = 1;
 			continue;
-		} else if (hdiff < 0) {
-			/* The low key is larger than the upper range; pop. */
-			goto pop_up;
 		}
 		cur->bc_levels[level].ptr++;
 	}
@@ -4971,8 +4962,8 @@ xfs_btree_query_range(
 	xfs_btree_key_from_irec(cur, &high_key, high_rec);
 	xfs_btree_key_from_irec(cur, &low_key, low_rec);
 
-	/* Enforce low key < high key. */
-	if (cur->bc_ops->diff_two_keys(cur, &low_key, &high_key) > 0)
+	/* Enforce low key <= high key. */
+	if (!xfs_btree_keycmp_le(cur, &low_key, &high_key))
 		return -EINVAL;
 
 	if (!(cur->bc_flags & XFS_BTREE_OVERLAPPING))

fs/xfs/libxfs/xfs_btree.h

@@ -546,6 +546,61 @@ int xfs_btree_has_record(struct xfs_btree_cur *cur,
 bool xfs_btree_has_more_records(struct xfs_btree_cur *cur);
 struct xfs_ifork *xfs_btree_ifork_ptr(struct xfs_btree_cur *cur);
 
+/* Key comparison helpers */
+static inline bool
+xfs_btree_keycmp_lt(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2)
+{
+	return cur->bc_ops->diff_two_keys(cur, key1, key2) < 0;
+}
+
+static inline bool
+xfs_btree_keycmp_gt(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2)
+{
+	return cur->bc_ops->diff_two_keys(cur, key1, key2) > 0;
+}
+
+static inline bool
+xfs_btree_keycmp_eq(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2)
+{
+	return cur->bc_ops->diff_two_keys(cur, key1, key2) == 0;
+}
+
+static inline bool
+xfs_btree_keycmp_le(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2)
+{
+	return !xfs_btree_keycmp_gt(cur, key1, key2);
+}
+
+static inline bool
+xfs_btree_keycmp_ge(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2)
+{
+	return !xfs_btree_keycmp_lt(cur, key1, key2);
+}
+
+static inline bool
+xfs_btree_keycmp_ne(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_key	*key1,
+	const union xfs_btree_key	*key2)
+{
+	return !xfs_btree_keycmp_eq(cur, key1, key2);
+}
+
 /* Does this cursor point to the last block in the given level? */
 static inline bool
 xfs_btree_islastblock(

fs/xfs/scrub/btree.c

@@ -161,20 +161,20 @@ xchk_btree_rec(
 	if (cur->bc_nlevels == 1)
 		return;
 
-	/* Is this at least as large as the parent low key? */
+	/* Is low_key(rec) at least as large as the parent low key? */
 	cur->bc_ops->init_key_from_rec(&key, rec);
 	keyblock = xfs_btree_get_block(cur, 1, &bp);
 	keyp = xfs_btree_key_addr(cur, cur->bc_levels[1].ptr, keyblock);
-	if (cur->bc_ops->diff_two_keys(cur, &key, keyp) < 0)
+	if (xfs_btree_keycmp_lt(cur, &key, keyp))
 		xchk_btree_set_corrupt(bs->sc, cur, 1);
 
 	if (!(cur->bc_flags & XFS_BTREE_OVERLAPPING))
 		return;
 
-	/* Is this no larger than the parent high key? */
+	/* Is high_key(rec) no larger than the parent high key? */
 	cur->bc_ops->init_high_key_from_rec(&hkey, rec);
 	keyp = xfs_btree_high_key_addr(cur, cur->bc_levels[1].ptr, keyblock);
-	if (cur->bc_ops->diff_two_keys(cur, keyp, &hkey) < 0)
+	if (xfs_btree_keycmp_lt(cur, keyp, &hkey))
 		xchk_btree_set_corrupt(bs->sc, cur, 1);
 }
 
@@ -209,20 +209,20 @@ xchk_btree_key(
 	if (level + 1 >= cur->bc_nlevels)
 		return;
 
-	/* Is this at least as large as the parent low key? */
+	/* Is this block's low key at least as large as the parent low key? */
 	keyblock = xfs_btree_get_block(cur, level + 1, &bp);
 	keyp = xfs_btree_key_addr(cur, cur->bc_levels[level + 1].ptr, keyblock);
-	if (cur->bc_ops->diff_two_keys(cur, key, keyp) < 0)
+	if (xfs_btree_keycmp_lt(cur, key, keyp))
 		xchk_btree_set_corrupt(bs->sc, cur, level);
 
 	if (!(cur->bc_flags & XFS_BTREE_OVERLAPPING))
 		return;
 
-	/* Is this no larger than the parent high key? */
+	/* Is this block's high key no larger than the parent high key? */
 	key = xfs_btree_high_key_addr(cur, cur->bc_levels[level].ptr, block);
 	keyp = xfs_btree_high_key_addr(cur, cur->bc_levels[level + 1].ptr,
 			keyblock);
-	if (cur->bc_ops->diff_two_keys(cur, keyp, key) < 0)
+	if (xfs_btree_keycmp_lt(cur, keyp, key))
 		xchk_btree_set_corrupt(bs->sc, cur, level);
 }
 
@@ -557,7 +557,7 @@ xchk_btree_block_check_keys(
 	parent_block = xfs_btree_get_block(cur, level + 1, &bp);
 	parent_low_key = xfs_btree_key_addr(cur, cur->bc_levels[level + 1].ptr,
 			parent_block);
-	if (cur->bc_ops->diff_two_keys(cur, &block_key, parent_low_key)) {
+	if (xfs_btree_keycmp_ne(cur, &block_key, parent_low_key)) {
 		xchk_btree_set_corrupt(bs->sc, bs->cur, level);
 		return;
 	}
@@ -569,7 +569,7 @@ xchk_btree_block_check_keys(
 	parent_high_key = xfs_btree_high_key_addr(cur,
 			cur->bc_levels[level + 1].ptr, parent_block);
 	block_high_key = xfs_btree_high_key_from_key(cur, &block_key);
-	if (cur->bc_ops->diff_two_keys(cur, block_high_key, parent_high_key))
+	if (xfs_btree_keycmp_ne(cur, block_high_key, parent_high_key))
 		xchk_btree_set_corrupt(bs->sc, bs->cur, level);
 }
 
@@ -661,7 +661,7 @@ xchk_btree_block_keys(
 	parent_keys = xfs_btree_key_addr(cur, cur->bc_levels[level + 1].ptr,
 			parent_block);
 
-	if (cur->bc_ops->diff_two_keys(cur, &block_keys, parent_keys) != 0)
+	if (xfs_btree_keycmp_ne(cur, &block_keys, parent_keys))
 		xchk_btree_set_corrupt(bs->sc, cur, 1);
 
 	if (!(cur->bc_flags & XFS_BTREE_OVERLAPPING))
@@ -672,7 +672,7 @@ xchk_btree_block_keys(
 	high_pk = xfs_btree_high_key_addr(cur, cur->bc_levels[level + 1].ptr,
 			parent_block);
 
-	if (cur->bc_ops->diff_two_keys(cur, high_bk, high_pk) != 0)
+	if (xfs_btree_keycmp_ne(cur, high_bk, high_pk))
 		xchk_btree_set_corrupt(bs->sc, cur, 1);
 }