selftests/damon/sysfs: test damon_target filter

Test existence of files and validity of input keyword for DAMON monitoring
target based DAMOS filter on DAMON sysfs interface.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: SeongJae Park <[e-mail]>
Cc: Brendan Higgins <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/damon/sysfs.sh

···
 	ensure_write_succ "$filter_dir/type" "anon" "valid input"
 	ensure_write_succ "$filter_dir/type" "memcg" "valid input"
 	ensure_write_succ "$filter_dir/type" "addr" "valid input"
+	ensure_write_succ "$filter_dir/type" "target" "valid input"
 	ensure_write_fail "$filter_dir/type" "foo" "invalid input"
 	ensure_file "$filter_dir/matching" "exist" "600"
 	ensure_file "$filter_dir/memcg_path" "exist" "600"
 	ensure_file "$filter_dir/addr_start" "exist" "600"
 	ensure_file "$filter_dir/addr_end" "exist" "600"
+	ensure_file "$filter_dir/damon_target_idx" "exist" "600"
 }
 
 test_filters()