btrfs-progs: zoned: create a data block-group for relocation

Create a second data block-group to be used for relocation, in case a
zoned filesystem in created.

This second data block-group will then be picked up by the kernel as the
default data relocation block-group on mount.

This ensures we always have a target to relocate good data to when we
need to do garbage collection.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: morbidrsa

mkfs/main.c

@@ -2039,6 +2039,15 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		goto error;
 	}
 
+	if (features.incompat_flags & BTRFS_FEATURE_INCOMPAT_ZONED) {
+		ret = create_data_block_groups(trans, root, mixed, &allocation);
+		if (ret) {
+			errno = -ret;
+			error("failed to create data relocation block groups: %m");
+			goto error;
+		}
+	}
+
 	if (features.incompat_flags & BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2) {
 		ret = create_global_roots(trans, nr_global_roots);
 		if (ret) {