range: Add range_overlaps()

Code to support CXL Dynamic Capacity devices will have extent ranges
which need to be compared for intersection not a subset as is being
checked in range_contains().

range_overlaps() is defined in btrfs with a different meaning from what
is required in the standard range code.  Dan Williams pointed this out
in [1].  Adjust the btrfs call according to his suggestion there.

Then add a generic range_overlaps().

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org
Link: https://lore.kernel.org/all/65949f79ef908_8dc68294f2@dwillia2-xfh.jf.intel.com.notmuch/ [1]
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/20241107-dcd-type2-upstream-v7-1-56a84e66bc36@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

fs/btrfs/ordered-data.c

@@ -111,8 +111,8 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
 	return NULL;
 }
 
-static int range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
-			  u64 len)
+static int btrfs_range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
+				u64 len)
 {
 	if (file_offset + len <= entry->file_offset ||
 	    entry->file_offset + entry->num_bytes <= file_offset)
@@ -985,7 +985,7 @@ struct btrfs_ordered_extent *btrfs_lookup_ordered_range(
 
 	while (1) {
 		entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
-		if (range_overlaps(entry, file_offset, len))
+		if (btrfs_range_overlaps(entry, file_offset, len))
 			break;
 
 		if (entry->file_offset >= file_offset + len) {
@@ -1114,12 +1114,12 @@ struct btrfs_ordered_extent *btrfs_lookup_first_ordered_range(
 	}
 	if (prev) {
 		entry = rb_entry(prev, struct btrfs_ordered_extent, rb_node);
-		if (range_overlaps(entry, file_offset, len))
+		if (btrfs_range_overlaps(entry, file_offset, len))
 			goto out;
 	}
 	if (next) {
 		entry = rb_entry(next, struct btrfs_ordered_extent, rb_node);
-		if (range_overlaps(entry, file_offset, len))
+		if (btrfs_range_overlaps(entry, file_offset, len))
 			goto out;
 	}
 	/* No ordered extent in the range */

include/linux/range.h

@@ -13,11 +13,19 @@ static inline u64 range_len(const struct range *range)
 	return range->end - range->start + 1;
 }
 
+/* True if r1 completely contains r2 */
 static inline bool range_contains(struct range *r1, struct range *r2)
 {
 	return r1->start <= r2->start && r1->end >= r2->end;
 }
 
+/* True if any part of r1 overlaps r2 */
+static inline bool range_overlaps(const struct range *r1,
+				  const struct range *r2)
+{
+	return r1->start <= r2->end && r1->end >= r2->start;
+}
+
 int add_range(struct range *range, int az, int nr_range,
 		u64 start, u64 end);